Biomedical subjects

S J Mentzer

Publications and source records attributed to S J Mentzer.

At least 19 recordsLinked to original sources

PubMed2002

Spatial variation of plasma flow in the oxazolone-stimulated microcirculation.

INTRODUCTION: In cutaneous lymphocytic inflammation, enhanced regional blood flow is suggested by persistent erythema and warmth. Direct assessment of the microcirculation, however, has been limited by tissue edema and skin thickness. METHODS: To assess the microcirculatory adaptations to the epicutaneous antigen oxazolone, we studied the first pass kinetics and microvascular topography of the inflammatory skin microcirculation using a specially adapted epi-illumination intravital microscopy system. The fluorescence intravital videomicroscopy and streaming image acquisition of fluorescein-labeled dextran (approximately 500,000 MW) injections were used to assess changes in plasma flow. RESULTS: Direct plasma tracer injections of both the oxazolone-stimulated and control microcirculation demonstrated comparable transit times (leading edge and intensity-weighted peak times) from the carotid artery to the superficial vascular plexus (p > 0.05). In contrast to transit times, continuous infusion of the plasma tracer demonstrated a significant increase in the delivery of the fluorescein-labeled dextran to the oxazolone-stimulated microcirculation. Quantitative morphometry of intravital microscopic images demonstrated a 2.2-fold increase in the mean diameter of vessels in the superficial vascular plexus (p < 0.01). Further, fluorescence intensity mapping indicated that the increase was associated with increased perfusion of focal regions of the superficial vascular plexus (p < 0.001). CONCLUSIONS: These results indicate that the oxazolone-stimulated adaptations of the inflammatory microcirculation include both microvascular dilatation and the redistribution of plasma flow.

Animals↗

PubMed2001

Biphasic response of the regional lymphatics in the normal lymphocyte transfer reaction.

BACKGROUND: Initially developed for histocompatibility testing, the normal lymphocyte transfer (NLT) reaction involves the intradermal injection of allogeneic lymphocytes from one individual to another. Because of the unique kinetics of the immunological response to allogeneic lymphocytes, the NLT reaction has been considered an informative system for the analysis of transplant immunity. METHODS: In this study, we used bilateral efferent lymph duct cannulations in sheep to examine the regional lymphatic response to the NLT reaction. Our studies used monoclonal antibodies to define lymphocyte population dynamics and DNA flow cytometry to reflect lymphocyte proliferative responses. RESULTS: The results confirmed a biphasic NLT reaction. An unexpected finding was the marked differences between the early and late NLT responses. The early response was characterized by T-lymphocyte proliferation, as reflected by S-phase DNA, which was comparable in both the NLT-stimulated and contralateral control efferent lymphocytes. This bilateral proliferative response was observed in both CD4+ and CD8+ lymphocytes. In contrast, the late response was restricted to the efferent lymph from the NLT-stimulated lymph node. Dual-parameter flow cytometry demonstrated that the dominant component of this unilateral NLT response was CD8+ lymphocytes. CONCLUSIONS: These results suggest important functional distinctions between systemic and regional lymphatic responses to intradermal alloantigens.

Animals↗

PubMed2001

Bronchoscopic volume reduction: a safe and effective alternative to surgical therapy for emphysema.

Lung volume reduction surgery (LVRS), the removal of damaged, hyperexpanded lung, has been shown to improve respiratory function in many patients with end-stage emphysema. We report the results of an animal study using a new transbronchoscopic alternative to LVRS in which a washout solution and fibrin-based glue are used to collapse, seal, and scar target regions of abnormal lung. Twelve sheep had static and dynamic lung functions measured at baseline. Emphysema was produced by inhaled papain (7,000 U/wk x 4 wk), resulting in a significant increase of lung volumes, compliance, and airway resistance. The animals were then divided into three treatment groups of four animals, and underwent surgical volume reduction (SVR), bronchoscopic volume reduction (BVR), or bronchoscopy alone (Sham-BVR). Response to each intervention was assessed 8 to 12 wk after treatment by measuring lung function and examining lung tissue. BVR and SVR groups responded with significant and similar decreases in TLC and residual volume (RV). Tissue examination demonstrated that BVR caused collapse of the lung with focal scarring in 11 of 20 target territories (55% success rate). Three of the 11 target zones developed sterile abscesses. Postprocedure complications were less frequent with BVR than with SVR. This pilot study suggests that lung volume reduction can be achieved in animals without surgery using a bronchoscopic approach and a novel fibrin-based glue system. BVR has the potential for simplifying volume reduction, extending indications, and reducing morbidity, mortality, and costs in humans.

Animals↗

PubMed2001

Cytolytic peptides induce biphasic permeability changes in mammalian cell membranes.

The cytolytic peptides melittin and gramicidin S are naturally occurring agents that provide a comparative model for studies of complement, immunotoxin and cell-mediated membrane permeability. Most attempts to characterize cytolytic peptides have used model membrane systems including phospholipid vesicles or erythrocytes. Membrane vesicles permit the use of self-quenching concentrations of fluorescent permeability markers, while erythrocytes release measurable hemoglobin. Attempts at measuring early membrane permeability changes in nucleated mammalian cells have been limited. To measure the kinetics of mammalian cell membrane permeability changes induced by cytolytic peptides, we developed a 96-well fluorescence cytolysis assay using the cytoplasmic fluorescent dye calcein as the membrane permeability marker. To facilitate rapid assessment of membrane permeability, trypan blue was added to the assay solution to quench (a) released fluorescence and (b) retained intracellular fluorescence. Trypan blue also provided a complementary visual assessment of cell viability. Using this assay, a detailed kinetic analysis demonstrated permeability of the cell membranes within seconds of exposure to the cytolytic peptides. The rapid permeabilization of the cell membranes was confirmed by flow cytometry using the calcium indicator dye fluo-3. The assay also demonstrated a second slower phase of marker release over the next several hours. The fluorescence cytolysis assay was able to reliably detect the biphasic permeability changes associated with the melittin and gramicidin S peptides suggesting the potential utility of this assay in the assessment of other cytolytic agents.

Animals↗

PubMed2001

Stochastic regulation of cell migration from the efferent lymph to oxazolone-stimulated skin.

The systemic immune response is a dynamic process involving the trafficking of lymphocytes from the Ag-stimulated lymph node to the peripheral tissue. Studies in sheep have demonstrated several phases of cell output in the efferent lymph after Ag stimulation. When skin contact sensitizers are used as Ag, the efferent lymph cell output peaks approximately 96 h after Ag stimulation and is temporally associated with the recruitment of cells into the skin. To investigate the relative contribution of this high-output phase of efferent lymphocytes to lymphocytic inflammation in the skin, we used a common contact sensitizer 2-phenyl-4-ethoxymethylene-5-oxazolone (oxazolone) to stimulate the skin and draining prescapular lymph node of adult sheep. The efferent lymph ducts draining the Ag-stimulated and contralateral control lymph nodes were cannulated throughout the experimental period. The lymphocytes leaving the lymph nodes during the 72-h period before maximum infiltration were differentially labeled with fluorescent tracers, reinjected into the arterial circulation, and tracked to the site of Ag stimulation. Quantitative tissue cytometry of the skin at the conclusion of the injection period (96 h after Ag stimulation) demonstrated more migratory cells derived from the Ag-stimulated lymph node than the contralateral control (median 18.5 vs 15.5 per field; p < 0.05). However, when corrected for total cell output of the lymph node, the Ag-stimulated migratory cells were 3.8-fold more prevalent in the skin than the contralateral control cells. These results suggest that the in situ immune response generally mirrors the frequency of recruitable lymphocytes in the peripheral blood.

Adjuvants, Immunologic↗

PubMed2001

Transthoracic esophagectomy with radical mediastinal and abdominal lymph node dissection and cervical esophagogastrostomy for esophageal carcinoma.

BACKGROUND: Several techniques for esophageal resection have been reported. This study examines the morbidity, mortality, and early survival of patients after transthoracic esophagectomy for esophageal carcinoma using current staging techniques and neoadjuvant therapy. The technique includes right thoracotomy, laparotomy, and cervical esophagogastrostomy (total thoracic esophagectomy) with radical mediastinal and abdominal lymph node dissection. METHODS: Three hundred forty-two patients had surgery for esophageal carcinoma between 1989 and 2000 at our institution. Two hundred fifty consecutive patients had esophagectomy using this technique. Kaplan-Meier curves and univariate and multivariate analyses were performed by postsurgical pathologic stage. RESULTS: Median age was 62.7 years (31 to 86 years). Fifty-nine were female. Eighty-one percent (202) had induction chemotherapy (all patients with clinical T3/4 or N1). Early postoperative complications included recurrent laryngeal nerve injury (14% [35]), chylothorax (9%, [22]), and leak (8%, [19]). Median length of stay was 13 days (5 to 330 days). In-hospital or 30-day mortality was 3.6% (9). Overall survival at 3 years was 44%; median survival was 25 months, and 3-year survival by posttreatment pathologic stage was: stage 0 (complete response) (n = 60), 56%; stage I (n = 32), 65%; stage IIA (n = 67), 41%; stage IIB (n = 30), 46%; and stage III (n = 49), 17%. Mean follow-up was 24 months (SEM 1.6, 0 to 138 months). Five patients with tumor in situ, 6 patients with stage IV disease, and 1 patient who could not be staged (12 pts) were excluded from survival and multivariate calculations. In univariate and different models of multivariate analysis, age more than 65 years, posttreatment T3, and nodal involvement were predictive of poor survival. For univariate analysis, p = 0.002, p = 0.004, p = 0.02, respectively; for multivariate analysis, p = 0.001, p = 0.003, p = 0.02, respectively. CONCLUSIONS: Total thoracic esophagectomy with node dissection for esophageal cancer appears to have acceptable morbidity and mortality with encouraging survival results in the setting of neoadjuvant therapy. Patients who show complete response after induction chemoradiotherapy appear to have improved long-term survival.

Abdomen↗

PubMed2001

Epstein--Barr virus post-transplant lymphoproliferative disease and virus-specific therapy: pharmacological re-activation of viral target genes with arginine butyrate.

Lymphoproliferative disorders associated with the Epstein-Barr virus (EBV) include non-Hodgkin's lymphoma, Hodgkin's lymphoma, and "post-transplant lymphoproliferative disorders" (PTLD), which occur with immunosuppression after marrow and organ transplantation. PTLD is characterized by actively proliferating, latently infected EBV(+) B-lymphocytes, and often manifests a rapidly progressive fatal clinical course if the immunosuppression cannot be reversed. Lung transplant recipients are a subset of patients at special risk for developing PTLD. The incidence of PTLD development in these patients has been estimated at 5--10%. Whereas immunologic and antiviral therapy have been moderately effective for treating EBV-associated infections in the lytic phase, they have been less useful in the more common latent phase of the disease. One common treatment for herpesvirus infections has targeted the virus-specific enzyme thymidine kinase (TK). The lack of viral TK expression in EBV(+) tumor cells, due to viral latency, makes anti-viral therapy alone ineffective as an anti-neoplastic therapy, however. We have developed a strategy for the treatment of EBV-associated lymphomas/PTLD using pharmacologic induction of the latent viral TK gene and enzyme in the tumor cells, followed by treatment with ganciclovir. Arginine butyrate selectively activates the EBV TK gene in latently EBV-infected human lymphoid cells and tumor cells. A Phase I/II trial has been initiated, employing an intra-patient dose escalation of arginine butyrate combined with ganciclovir. In six patients with EBV-associated lymphomas or PTLD, all of which were resistant to conventional radiation and/or chemotherapy, this combination produced complete clinical responses in four of six patients, with a partial response occurring in a fifth patient. Pathologic examination in two of three patients demonstrated complete necrosis of the EBV lymphoma, with no residual disease, following a single three-week course of the combination therapy. Possible side-effects of the therapy included nausea and reversible lethargy at the highest doses. One patient suffered acute liver failure, thought to be secondary to release of FasL from the necrotic tumor. Analysis of patient-derived tumor cells in culture demonstrated that arginine butyrate produced selective induction of the EBV TK gene, which then conferred sensitivity to ganciclovir, resulting in tumor apoptosis. Additional patient accrual is sought for further evaluation of this therapy.

Antineoplastic Agents↗

PubMed2001

Combined antegrade and retrograde dilation: a new endoscopic technique in the management of complex esophageal obstruction.

BACKGROUND: Esophageal strictures that cause complete obstruction are often difficult to dilate with standard bougienage techniques. METHODS: A new technique was developed and applied, combined antegrade and retrograde dilation, for dilatation of complex esophageal strictures. The stomach is accessed and an endoscope (9.8 mm diameter) is directed under fluoroscopy in a retrograde fashion into the distal esophagus. A guidewire with a hydrophilic coating is advanced through the stricture and then pulled through the mouth with a simultaneously placed proximal endoscope. The guidewire is then used as a guide for antegrade esophageal dilatation. RESULTS: Ten patients with complex esophageal strictures (with and without fistulas) were treated with this technique. Three required a second combined antegrade and retrograde dilation procedure. All strictures were dilated and no perforations occurred. CONCLUSIONS: Combined antegrade and retrograde dilation is a safe and effective technique for dilation of complex obstructing esophageal lesions.

Aged↗

PubMed2001

Sequential thoracic metastasectomy prolongs survival by re-establishing local control within the chest.

OBJECTIVE: The value of sequential thoracic metastasectomies is unknown. We evaluate repeat metastasectomy for limited recurrences within the thorax. METHODS: From July 1988 to September 1998, 54 patients underwent 2 to 6 separate sequential procedures to excise metastases after recurrence isolated to the thorax. Kaplan-Meier survival and Cox modeling determined prognostic variables. RESULTS: Thirty-three men and 21 women, 22 to 76 years underwent 2 (100%, n = 54), 3 (50%), 4 (22%), or 5 to 6 (11%) metastasectomies. Fifty-four percent of patients had carcinoma, 35% sarcoma, 9% germ cell, and 2% melanoma. There were no operative deaths; all late deaths occurred from cancer. Median follow-up was 48 months. Cumulative 5-year survival from the second procedure was 57%. After the second, third, fourth, and fifth procedures, respectively, permanent control was achieved in 15 (27%) of 54 patients, 5 (19%) of 27, 1 (8%) of 12, and 0 of 7. Recurrence amenable to additional surgery occurred in 27 (50%) of 54, 12 (44%) of 27, 6 (50%) of 12, and 1 (17%) of 6. Mean hazard for the development of unresectable recurrence increased from 0.21 after the second procedure to 0.91 after the fifth procedure. The 5-year survival for the 27 patients undergoing only 2 metastasectomies was 60% (median not yet reached), 33% for the 15 patients undergoing only 3 metastasectomies (median 34.7 months), and 38% for the 12 patients undergoing 4 or more (median 45.6 months). From the time a recurrence was declared unresectable, patients had a 19% 2-year survival (median 8 months). CONCLUSIONS: Multiple attempts to re-establish intrathoracic control of metastatic disease is justified in carefully selected patients, but the magnitude of benefit decays with each subsequent attempt.

Adult↗

PubMed2001

Induction of the Epstein-Barr virus thymidine kinase gene with concomitant nucleoside antivirals as a therapeutic strategy for Epstein-Barr virus-associated malignancies.

Lymphoproliferative diseases (LPDs) associated with the Epstein-Barr virus (EBV) include non-Hodgkin lymphomas, which occur in the setting of immunosuppression, including that induced by human immunodeficiency virus, and posttransplant lymphoproliferative disorders. These LPDs are characterized by actively proliferating, latently infected EBV-positive B lymphocytes and often follow a rapidly progressive fatal clinical course. Pharmacologic treatment for herpesvirus infections has targeted the virus-specific enzyme, thymidine kinase (TK), with nucleoside analogs. The lack of viral TK expression in EBV-positive tumors, caused by viral latency, however, makes antiviral therapy alone ineffective as an antineoplastic therapy. Arginine butyrate selectively activates the EBV TK gene in latently infected EBV-positive tumor cells. We have developed a strategy for treatment of EBV-associated lymphomas using pharmacologic induction of the latent viral TK gene and enzyme in tumor cells using arginine butyrate, followed by treatment with ganciclovir. A phase I/II trial, using an intrapatient dose escalation of arginine butyrate combined with ganciclovir, is underway. This combination therapy has produced complete clinical responses in 5 of 10 previously refractory patients, with partial responses occurring in 2 additional patients. This virus-targeted antitumor strategy may provide a new therapeutic approach to EBV-associated neoplasms.

Antineoplastic Agents↗

PubMed2001

Focal topographic changes in inflammatory microcirculation associated with lymphocyte slowing and transmigration.

Microcirculation is the primary mechanism for delivering lymphocytes to inflammatory tissues. Blood flow within microvessels ensures a supply of lymphocytes at the blood-endothelial interface. Whether the structure of the inflammatory microcirculation facilitates lymphocyte transmigration is less clear. To illuminate the microcirculatory changes associated with lymphocyte transmigration, we used intravital videomicroscopy to examine the dermal microcirculation after application of the epicutaneous antigen oxazolone. Intravascular injection of fluorescein-labeled dextran demonstrated focal topographic changes in the microcirculation. These focal changes had the appearance of loops or hairpin turns in the oxazolone-stimulated skin. Changes were maximal at 96 h and coincided with peak lymphocyte recruitment. To determine whether these changes were associated with lymphocyte transmigration, lymphocytes obtained from efferent lymph of draining lymph nodes at 96 h were fluorescently labeled and reinjected into inflammatory microcirculation. Epifuorescence intravital video microscopy demonstrated focal areas were associated with lymphocyte slowing and occasional transmigration. In contrast, focal loops and lymphocyte slowing were rarely observed in the contralateral control microcirculation. Results suggest that structural adaptations in inflammatory microcirculation represented by focal topographic changes may contribute to regulation of tissue entry by recirculating lymphocytes.

Adjuvants, Immunologic↗

PubMed2001

Inspiratory lung impedance in COPD: effects of PEEP and immediate impact of lung volume reduction surgery.

Frequency-dependent characteristics of lung resistance (RL) and elastance (EL) are sensitive to different patterns of airway obstruction. We used an enhanced ventilator waveform (EVW) to measure inspiratory RL and EL spectra in ventilated patients during thoracic surgery. The EVW delivers an inspiratory flow waveform with enhanced spectral excitation from 0.156 to 8.1 Hz. Estimates of the coefficients in a trigonometric approximation of the EVW flow and transpulmonary pressure inspirations yielded inspiratory RL and EL spectra. We applied the EVW in a group with mild obstruction undergoing various thoracoscopic procedures (n = 6), and another group with severe chronic obstructive pulmonary disease undergoing lung volume reduction surgery (n = 8). Measurements were made at positive end-expiratory pressure (PEEP) of 0, 3, and 6 cmH(2)O. Inspiratory RL was similar in both groups despite marked differences in spirometry. The chronic obstructive pulmonary disease patients demonstrated a pronounced frequency-dependent increase in inspiratory EL consistent with severe heterogeneous peripheral airway obstruction. PEEP appears to have beneficial effects by reducing peripheral airway resistance. Lung volume reduction surgery resulted in increased inspiratory RL and EL at all frequencies and PEEPs, possibly due to loss of diseased lung tissue, pulmonary edema, increased mechanical heterogeneity, and/or an improvement in airway tethering.

Adult↗

PubMed2001

Interpreting improvement in expiratory flows after lung volume reduction surgery in terms of flow limitation theory.

Spirometry and pulmonary mechanics were measured pre- and postoperatively in 37 patients undergoing bilateral lung volume reduction surgery (LVRS). The relative contributions of changes in compliance (CL), recoil pressures (PTLC), small airway conductance (Gu), and airway closing pressures (Ptm') to changes in expiratory flows were examined with a Taylor series expansion of the Pride- Permutt model of flow limitation. The resulting variational expression, deltaVmax = GudeltaPel + PeldeltaGu - GudeltaPtm' - Ptm'deltaGu - deltaGudeltaPtm', was then used to describe how the peak flow rate (Vmax) depends on preoperative Gu, P TLC, Ptm', and on changes (delta) in these parameters after surgery. After LVRS, both FEV(1) and Vmax increased significantly ( DeltaFEV(1) = 28 +/- 44%; DeltaVmax = 78 +/- 132%), and changes in FEV(1) and Vmax correlated closely (r = 0.74, p < 0.001). Among responders (DeltaFEV(1) > or = 12%; n = 19; DeltaFEV(1) = 60 +/- 38%), PTLC increased (8.8 +/- 2.8 to 12.2 +/- 4.7 cm H2O) and the time constant for expiration (tau = CL/Gu) decreased (2.67 +/- 0.62 to 2.35 +/- 0.55 s), while Ptm', CL, and Gu did not change. GudeltaPel, the change in recoil weighted by preoperative conductance upstream of the flow-limiting site, accounted for 72% of the improvement in Vmax. Among nonresponders ( DeltaFEV(1) = -6 +/- 15%, n = 18), tau increased significantly, contributing to a decline in FEV(1)/FVC ratio. PeldeltaGu decreased (-0.25 +/- 0.68, p = 0.013), accounting for all of the decline in Vmax. This analysis suggests that (1) improvement in expiratory flows after LVRS is largely due to increases in recoil pressure; (2) large improvements in FEV(1) can occur without changes in Gu or Ptm', arguing that LVRS has little effect on airway resistance or closure; and (3) large changes in PTLC can occur without changes in CL, supporting arguments of Fessler and Permutt (Am J Respir Crit Care Med 1998;157:715-722) that "resizing of the lung to chest wall" is the primary mechanism by which LVRS improves lung function.

Female↗

PubMed2001

Comparison of physiological and radiological screening for lung volume reduction surgery.

Physiological and radiological criteria are both used to identify candidates for LVRS. This study compares the predictive value of these screening techniques among patients with homogeneous (Ho) and heterogeneous (He) emphysema. Preoperative inspiratory lung conductance (G(Li)) during spontaneous breathing and quantitative radioisotope V/Q scan (QVQS) results were available for 48 of 50 patients undergoing bilateral LVRS for emphysema. Ho disease (n = 21) was defined by QVQS as an upper/lower perfusion ratio (ULPR) between 0.75 and1.25. G(Li) correlated with 6-mo improvement in FEV(1) (DeltaFEV(1)-6) (r = 0.53, p < 0.001) for the entire cohort, and for patients with both Ho (n = 21, r = 0.56, p = 0.015) and He disease (n = 27, r = 0.46, p = 0.017). ULPR correlated less well with DeltaFEV(1)-6 (n = 48, r = -0.38; p = 0.008) for the cohort, and was significantly correlated with outcomes only in the subgroup of patients with He disease (r = -0.40, p = 0.04). Multivariate regression demonstrated that by combining G(Li) and ULPR criteria, 33% of the DeltaFEV(1)-6 response could be accounted for. We conclude that both physiological and radiological criteria help identify appropriate candidates for LVRS. G(Li) best identifies patients with Ho emphysema who may benefit from surgery, but would be excluded on the basis of strictly radiological criteria. ULPR helps identify patients with He disease that improves with surgery, despite unfavorable G(Li).

Adult↗

PubMed2001

Aldehyde fixation of thiol-reactive fluorescent cytoplasmic probes for tracking cell migration.

Tracking of cell migration plays an important role in the study of morphogenesis, inflammation, and metastasis. The recent development of probes that exist as intracellular peptide-fluorescence dye adducts has offered the possibility of aldehyde fixation of these dyes for detailed anatomic studies of lymphocyte trafficking. To define the conditions for fixation of these cytoplasmic fluorescent probes, we compared fixation conditions containing formaldehyde, glutaraldehyde, paraformaldehyde, zinc formaldehyde, and glyoxylate, as well as fixation by quick-freezing in liquid nitrogen-cooled methylbutane. The efficacy of aldehyde fixation of the cell fluorescence was assessed by quantitative tissue cytometry and flow cytometry. We studied cytoplasmic fluorescent dyes with discrete emissions in the green [5-chloromethylfluorescein diacetate (CMFDA); 492 ex, 516 em] and orange [5-(and-6)-(4-chloromethyl(benzoyl)amino) tetramethylrhodamine (CMTMR); 540 ex, 566 em] spectra. The results demonstrated that aldehyde fixation preserved cell fluorescence for more than 6 months. The primary difference between the aldehyde fixatives was variability in the difference between the yield of the cell fluorescence and the relevant background fluorescence. Formaldehyde and paraformaldehyde were superior to the other fixatives in preserving cell fluorescence while limiting background fluorescence. With these fixatives, both the CMFDA and CMTMR fluorescent dyes permitted sufficient anatomic resolution for reliable localization in long-term cell tracking studies.

Aldehydes↗

PubMed2001

Effect of shear stress on efferent lymph-derived lymphocytes in contact with activated endothelial monolayers.

L.ymphocyte interactions with endothelial cells in microcirculation are an important regulatory step in the delivery of lymphocytes to peripheral sites of inflammation. In normal circumstances, the predicted wall shear stress in small venules range from 10 to 100 dyn/cm2. Attempts to measure the adhesion of lymphocytes under physiologic conditions have produced variable results, suggesting the importance of studying biologically relevant migratory lymphocytes. To quantify the effect of shear stress on these migratory lymphocytes, we used lymphocytes obtained from sheep efferent lymph ducts, defined as migratory cells, to perfuse sheep endothelial monolayers under conditions of flow. Quantitative cytomorphometry was used to distinguish cells in contact with the endothelial monolayers from cells in the flow stream. As expected, migratory cells in contact with the normal endothelial monolayer demonstrated flow velocities less than the velocity of cells in the adjacent flow stream. The flow velocities of these efferent lymphocytes were independent of cell size. To model the inflammatory microcirculation, lymphocytes were perfused over sequential endothelial monolayers to directly compare the velocity of cells in contact with cytokine-activated and unactivated control monolayers. The tumor necrosis factor and interleukin-1-activated endothelial monolayers marginally decreased cell velocities at 1.2 dyn/cm2 (3.6%), but significantly reduced cell velocities 0.3 dyn/cm2 (27.4%; P < 0.05). Similarly, the fraction of statically adherent lymphocytes decreased as shear stress increased to 1.2 dyn/cm2. These results suggest that typical wall shear stress in small venules. of the order of 20 dyn/cm2, are too high to permit adhesion and transmigration of migratory lymphocytes. Additional mechanisnis must be present in vivo to facilitate lymphocyte transmigration in the inflammatory microcircu-

Animals↗

PubMed2001

Molecular identification using flow cytometry histograms and information theory.

Flow cytometry is a common technique for quantitatively measuring the expression of individual molecules on cells. The molecular expression is represented by a frequency histogram of fluorescence intensity. For flow cytometry to be used as a knowledge discovery tool to identify unknown molecules, histogram comparison is a major limitation. Many traditional comparison methods do not provide adequate assessment of histogram similarity and molecular relatedness. We have explored a new approach applying information theory to histogram comparison, and tested it with histograms from 14 antibodies over 3 cell types. The information theory approach was able to improve over traditional methods by recognizing various non-random correlations between histograms in addition to similarity and providing a quantitative assessment of similarity beyond hypothesis testing of identity.

Animals↗

PubMed2000

Nodal stage after induction therapy for stage IIIA lung cancer determines patient survival.

BACKGROUND: This study was undertaken to determine the predictive value of nodal status at resection in regards to long-term outcome of patients undergoing neoadjuvant therapy and resection for stage IIIA N2-positive non-small cell lung cancer (NSCLC). METHODS: We reviewed the medical records of all patients found on surgical staging to have N2-positive NSCLC and who underwent induction therapy followed by resection between 1988 and 1996 at our hospital. Complete follow-up information was examined utilizing Kaplan-Meier survival analysis and Cox proportional hazards multivariate analysis. RESULTS: One hundred three patients (59 men) with stage IIIA N2-positive NSCLC received neoadjuvant therapy before surgical resection. Preoperative therapy consisted of platinum-based chemotherapy (76), radiotherapy (18), or chemoradiation (9). Operations included pneumonectomy (38), bilobectomy (6), and lobectomy (59). There were four deaths and seven major complications. Eighty-five patients were followed until death. Median survival among 18 living patients is 60.9 months (range 29 to 121 months). Twenty-nine patients were downstaged to N0 and had 5-year survival of 35.8% (median survival 21.3 months). Seventy-four patients with persistent tumor in their lymph nodes (25 N1 and 49 N2) had significantly worse, 9%, 5-year survival, p = 0.023 (median survival 15.9 months). Other negative prognostic factors were adenocarcinoma and pneumonectomy. CONCLUSIONS: Patients with N2-positive NSCLC whose nodal disease is eradicated after neoadjuvant therapy and surgery enjoy significantly improved cancer-free survival. These data support surgical resection for patients downstaged by induction therapy; however, patients who are not downstaged do not benefit from surgical resection. Direct effort should be made to improve the accuracy of restaging before resection.

Adult↗