Search PubMed⌕ Search

Biomedical subjects

A R Huber

Publications and source records attributed to A R Huber.

17 recordsLinked to original sources
PubMed2001

Urine analysis performed by flow cytometry: reference range determination and comparison to morphological findings, dipstick chemistry and bacterial culture results--a multicenter study.

AIM: To validate whether quantitative flow-cytometric analysis of particulate matter in urine would allow for accurate and rapid enumeration of red blood cells (RBC), leukocytes (WBC), squamous epithelial cells (EC), casts, and bacteria, a Sysmex UF-100 analyzer was tested in a multicenter study. MATERIAL AND METHODS: At first, reference values were established and found to be < 14 for RBC, < 16 for WBC, < 9 for EC, < 2 for casts and < 173 for bacteria, respectively (counts per microl; 97.5 percentile). Due to the wide use of dipstick and microscopic sediment analysis in routine urine diagnostics, comparative studies on 950 random urine samples were performed. Bacterial counting combined with WBC enumeration was further compared in 266 routine urinary microbiologic cultures. RESULTS: Good correlations were found comparing UF-100 results of RBC (r = 0.89), WBC (r = 0.94), and EC (r = 0.74) with Fuchs-Rosenthal Chamber (FRC) counts. However, some misclassification of casts (r = 0.32) could be observed. Correlations of UF-100 with dipstick and sediment testing was significant (p < 0.001), but the scatter of the latter two methods is too wide to consider them as quantitative methods. Promising results further revealed that the analyzer has a good negative predictive value (NPV) for microbiologically negative cultures, especially for cultures with bacterial counts of 10(5)/l (NPV = 95%). CONCLUSION: The analyzer is capable of providing rapid and reliable urine analysis of cellular particles avoiding the known imprecision of dipstick and sediment methodology. Thus, when used in an algorithm, combined with dipstick or quantitative urine chemistry analysis (for hemoglobin, esterase, protein, glucose, etc.), this analyzer might serve as a rapid and accurate screening tool in routine urine analysis, thereby reducing manual reviewing rate as well as the number of missed samples, compared to screening with dipstick alone.

Adolescent↗
PubMed2000

[Diagnosis of cerebrospinal fluid leakage at the base of the skull].

There are still several problems surrounding the diagnosis of cerebrospinal fluid leak. Currently the method of choice for cerebrospinal fluid detection is qualitative determination of beta-2-transferrin. Faster and more efficient methods (beta-trace) are under clinical investigation. The major problem is localisation of the site of leakage. Combination of several radiological methods increases the rate of correct diagnosis. In surgery the use of intrathecal sodium-fluorescein improves visualisation of the site of leakage and thus increases the chances of secure and stable closure of the cerebrospinal fluid fistula.

Cerebrospinal Fluid↗
PubMed2000

The role of automated urine particle flow cytometry in clinical practice.

Urine particle flow cytometers (UFC) have improved count precision and accuracy compared to visual microscopy and offer significant labor saving. The absence of an internationally recognized reference measurement procedure, however, is a serious drawback to their validation. Chamber counting by phase contrast microscopy of supravitally-stained uncentrifuged urine is considered the best candidate for reference. The UF-100 (Sysmex Corporation, Japan) identifies RBC, WBC, squamous epithelial cells, transitional epithelial and renal tubular cells (SRC), bacteria, hyaline and inclusional casts, yeast-like cells, crystals and spermatozoa, using argon laser flow cytometry. Evaluations have established acceptable linearity over useful working ranges, with an imprecision that is consistently and significantly less than microscopy, and with negligible carry-over. Comparisons of UFC with chamber counts, quantitative urine microscopy, sediment counts, test strips, bacterial culture and urine density are reviewed. Clinical studies include diagnosis and monitoring of urinary tract infection; localization of the sites of hematuria; and diagnosis, monitoring and exclusion of renal disease. The most popular approach is to combine test strips with UFC for primary screening either always by both methods or by using test strips for analytes unrelated to particles analyzed by UFC. Expert systems now exist combining both test modalities based on user definable decision rules. The implementation of such a strategy significantly reduces microscopy review and saves time and expense without diminishing clinical utility.

Bacteriuria↗
PubMed2000

ET gets HIT--thrombocytotic heparin-induced thrombocytopenia (HIT) in a patient with essential thrombocythemia (ET).

Immune-mediated heparin-induced thrombocytopenia (HIT) is a relatively common complication in patients receiving heparin, and represents a strong risk factor for thromboembolic disease associated with high morbidity and mortality. The condition is commonly defined as a platelet count fall of greater than 30-50% to values below 150 x 10(9)/l. Despite this, several cases with platelet count nadirs in the normal range have been reported. This report describes a patient with status post-carotid thrombendarterectomy presenting with neurological symptoms and thrombocytosis (1235 x 10(9)/l), which in due course was diagnosed to be caused by essential thrombocythemia (ET). Heparin therapy was established and symptoms resolved markedly. After 5 days of standard heparin therapy, serologically confirmed HIT with new neurological symptoms occurred. The platelet count nadir attributed to HIT was far above normal (633 x 10(9)/l), which nevertheless represented a substantial relative platelet count fall (49%). This is the first reported case of serologically confirmed HIT in a patient with ET. Furthermore, it represents the first published case of HIT being present in thrombocytosis. Clinicians should be aware that atypical HIT can even be present in thrombocytosis and, because of nomenclature, HIT with normal and elevated platelet count nadirs is likely to be largely underdiagnosed.

Heparin↗
PubMed1997

Inotropes inhibit endothelial cell surface adhesion molecules induced by interleukin-1beta.

OBJECTIVES: Leukocyte-endothelial cell interactions play a critical role in sepsis-induced multiple organ system failure and acute respiratory distress syndrome. Increased cyclic adenosine 3',5'-monophosphate (cAMP) has been previously reported to inhibit expression of the cytokine-stimulated endothelial cell adhesion molecules, E-selectin, and vascular cell adhesion molecule-1 (VCAM-1). We hypothesized that clinically relevant concentrations of inotropes, such as amrinone and dopamine, which increase cAMP, could inhibit cytokine-stimulated upregulation of endothelial adhesion proteins. DESIGN: Prospective, controlled in vitro study. SETTING: Leukocyte biology laboratory. SUBJECTS: Human umbilical vein endothelial cells isolated from neonatal umbilical cord specimens and whole blood obtained from normal human adult volunteers were used in this study. INTERVENTIONS: Endothelial cell monolayers were pretreated with increasing concentrations of amrinone or dopamine, or left untreated as controls, followed by exposure to recombinant human interleukin (IL)-1beta for 6 hrs. Monolayers were then incubated with monoclonal antibodies to E-selectin, VCAM-1, and intercellular adhesion molecule-1 (ICAM-1), fluorescence labeled, and assessed for mean fluorescence intensity by flow cytometry as a measure of surface adhesion molecule concentrations. Whole blood neutrophils were pretreated with or without inotropes, then stimulated with n-formyl methyl leucine phenylalanine. Stimulated neutrophils were incubated with antibodies against the neutrophil adherence protein CD11b and assessed by flow cytometry. MEASUREMENTS AND MAIN RESULTS: IL-1beta markedly increased E-selectin (p = .01), VCAM-1 (p < .01), and ICAM-1 (p < .001) concentrations (n = 6). Pretreatment with amrinone significantly decreased endothelial E-selectin surface values at all concentrations (p < .001 by analysis of variance, n = 5), including therapeutic concentration ranges. Amrinone also inhibited upregulation of ICAM-1 (p < .001) at therapeutic concentrations, and VCAM-1 (p < .001) at higher concentrations. Dopamine inhibited only E-selectin at relevant concentrations. Neutrophil pretreatment with inotropes did not prevent CD11b upregulation. CONCLUSIONS: Pretreatment with amrinone, and to a lesser degree, with dopamine, at clinically relevant concentrations inhibits in vitro IL-1alpha-induced increases in human umbilical vein endothelial cell adhesion molecule concentrations. Future studies are necessary to investigate the mechanisms of these effects and to determine in vivo efficacy of inotropes as anti-inflammatory agents.

Adult↗
PubMed1992

Monocyte diapedesis through an in vitro vessel wall construct: inhibition with monoclonal antibodies to thrombospondin.

Human peripheral blood monocytes were examined for migration across an endothelial cell monolayer in an in vitro vessel wall construct. Few monocytes invaded in the absence of a chemotactic gradient, despite significant adhesion to the endothelial monolayer. However, the addition of zymosan-activated human plasma to the lower compartment, to create a chemotactic gradient across the vessel wall, resulted in significantly enhanced monocyte migration. Pretreatment of the monocytes with monoclonal antibodies to thrombospondin (TSP) dramatically inhibited monocyte diapedesis into the vessel wall. The same treatment inhibited monocyte adhesion to endothelial cells in two-dimensional monolayer cultures as well as in vessel wall constructs (no chemotactic gradient). Of interest, however, the monoclonal antibodies had no inhibitory effect on monocyte migration into collagen gels devoid of endothelial cells in response to the same chemotactic gradient, suggesting the importance of TSP in monocyte-endothelial cell interactions. Monoclonal antibodies to fibronectin and normal mouse immunoglobulin G did not inhibit migration in this model of a vessel wall. Furthermore, monoclonal antibodies to TSP showed no inhibition of human peripheral blood neutrophil migration. Previous studies have shown that monocytes synthesize TSP and express this moiety on their surface. The present data suggest that monocytes may utilize TSP to interact with endothelial cells lining the vessel wall during diapedesis.

Antibodies, Monoclonal↗
PubMed1992

Modulation and function of intercellular adhesion molecule-1 (CD54) on human retinal pigment epithelial cells.

As part of the blood-retina barrier, the neuroectodermally-derived retinal pigment epithelial (RPE) monolayer is strategically positioned to interact with circulating leukocytes and regulate their access to the retina. We, therefore, studied whether human RPE cells express intercellular adhesion molecule-1 (ICAM-1), a specialized cell surface glycoprotein that binds the leukocyte function antigen-1 receptor present on all leukocytes. Using specific monoclonal antibody to ICAM-1, immunohistochemical staining of freshly-isolated primary and fourth passaged human RPE cells resulted in delicate reaction product that increased dramatically upon exposure to human recombinant (r) interferon-gamma (rIFN-gamma), interleukin-1-beta (rIL-1 beta), or tumor necrosis factor-alpha (rTNF-alpha). Fluorescence-activated cell sorting analysis demonstrated 2-fold increases in constitutive RPE ICAM-1 expression within 6 hours of exposure to physiologic concentrations of rIFN-gamma, rIL-1 beta, or rTNF-alpha. In standardized leukocyte adherence assays, cultured RPE cells showed avid binding of neutrophils that increased significantly after stimulation with rIFN-gamma, rIL-1 beta, or rTNF-alpha (p less than 0.001). In parallel assays, monoclonal antibody to either ICAM-1 on RPE cells, or subunits of leukocyte function antigen-1 receptors on leukocytes significantly blocked leukocyte binding to unstimulated (p less than 0.001) or rIFN-gamma-stimulated RPE cells (p less than 0.001). To demonstrate RPE ICAM-1 expression in intact human tissue, fresh uveoretinal explants were exposed to rIFN-gamma, rIL-1 beta, or rTNF-alpha and stained using mAb to ICAM-1. Tissue sections of cytokine-stimulated explants revealed dramatic increases in RPE ICAM-1 immunoreactivity over the low levels observed in unstimulated uveoretinal tissue. Our results indicate that: (a) ICAM-1 is expressed at low levels on unstimulated RPE cells, (b) RPE ICAM-1 may be augmented by inflammatory cytokines, and (c) RPE ICAM-1 is a functional receptor mediating leukocyte binding. ICAM-1 on RPE cells at the blood-retina barrier may regulate leukocytic infiltration in ocular diseases in which leukocytes are important pathogenetically and may be important to the generation of ocular immune responses.

Cell Adhesion↗
PubMed1992

Differential expression of human corneal and perilimbal ICAM-1 by inflammatory cytokines.

The mechanisms that regulate corneal infiltration by circulating leukocytes in inflammatory diseases are poorly understood. In this study, we investigated the effects of pro-inflammatory cytokines on corneal endothelial (CE) and stromal (CS) expression of intercellular adhesion molecule-1 (ICAM-1), a specialized cell surface glycoprotein that binds the leukocyte function antigen-1 (LFA-1) receptor present on all leukocytes and enhances immune responses. Using specific monoclonal antibody (mAb) to ICAM-1, immunohistochemical staining of intact human corneas resulted in discrete, granular reaction product in CE and CS cells as well as perilimbal vascular endothelium that increased dramatically when exposed to human recombinant interleukin-1-beta (rIL-1 beta), tumor necrosis factor-alpha (rTNF-alpha), and interferon-gamma (rIFN-gamma). Immunoreactive ICAM-1 in CE and CS cells was differentially increased by each of these cytokines. In contrast, immunoreactive endothelial-leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1 were not detected in any CE or CS cells of unstimulated or cytokine-stimulated corneas. In standardized leukocyte adherence assays, neutrophil binding to CE surfaces of whole corneas increased significantly upon exposure to rIL-1 beta, rTNF-alpha, or rIFN-gamma (P less than 0.001). In parallel assays, mAb to ICAM-1 on CE cells or subunits of LFA-1 receptors on leukocytes, but not control mAb, significantly blocked leukocyte binding to unstimulated (P less than 0.01) or rIFN-gamma-stimulated corneas (P less than 0.001). Our results indicate that: (1) ICAM-1 is expressed at low levels on unstimulated CE cells, CS cells, and perilimbal vascular endothelium; (2) ICAM-1 may be augmented differentially in corneal and perilimbal tissue by pro-inflammatory cytokines; and (3) ICAM-1 is a functional ligand mediating corneal-leukocyte binding. Differential expression of ICAM-1 within corneal tissue may regulate keratitic precipitate formation, leukocyte trafficking and accumulation, and localized generation of immune responses.

Cell Adhesion Molecules↗
PubMed1991

Regulation of transendothelial neutrophil migration by endogenous interleukin-8.

Movement of neutrophils from the bloodstream to inflamed tissue depends on the activation of both the neutrophil and the endothelial cell. Endothelial cells lining the postcapillary venule respond to proinflammatory mediators by expressing adhesion molecules and synthesizing a variety of neutrophil-activating factors. Endothelial cell production of a 77-amino acid variant of interleukin-8 (IL-8) was found to be a requirement for the invasion of neutrophils through a vessel wall model. IL-8 secreted by cytokine- or lipopolysaccharide-stimulated endothelial cells induced the rapid shedding of neutrophil lectin adhesion molecule-1, the up-regulation of leukocyte beta 2 integrins, and the attachment and transmigration of the neutrophils. Thus, endogenous endothelial IL-8 regulates transvenular traffic during acute inflammatory responses.

Antigens, CD↗
PubMed1991

Intercellular adhesion molecule-1 in human corneal endothelium. Modulation and function.

The endothelium lining the posterior corneal surface performs physiologic pump functions essential to corneal clarity and integrity. A hallmark of keratitis, anterior ocular inflammation, and corneal allograft rejection is leukocyte adherence to the corneal endothelium (CE) forming keratitic precipitates. To elucidate mechanisms governing cornea-leukocyte interactions, cultured human CE cells and intact corneas were examined for expression of intercellular adhesion molecule-1 (ICAM-1), which binds the lymphocyte function-associated antigen-1 (LFA-1) on all leukocytes and enhances delayed-type hypersensitivity mediated by class II major histocompatibility complex antigens. Immunohistochemistry on culture CE cells using monoclonal anti-ICAM-1 antibody yield positive staining that increased after exposure to interleukin-1-beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (gamma-IFN). Standard leukocyte adherence assays demonstrated ICAM-1-mediated CE-neutrophil binding, which was specifically blocked by antibody to ICAM-1 or antibodies to LFA-1 on neutrophils. In whole human corneas, gamma-IFN increased CE and stromal keratocyte ICAM-1 immunoreactivity and enhanced CE-neutrophil adherence. As in CE cell cultures, antibody to ICAM-1 effectively blocked neutrophil binding to the CE cells of whole corneas. These results are the first to demonstrate ICAM-1 in ocular tissue. They indicate that CE cells express functional ICAM-1, which may be modulated by inflammatory cytokines, ICAM-1 provides mechanisms for keratitic precipitate formation, regulation of corneal leukocyte trafficking and the generation of immune responses that may be crucial to allograft rejection.

Cell Adhesion Molecules↗
PubMed1989

Disruption of the subendothelial basement membrane during neutrophil diapedesis in an in vitro construct of a blood vessel wall.

To examine the course of physiologic interactions between extravasating neutrophils and the subendothelial basement membrane, a model of the venular vessel wall was constructed by culturing human umbilical vein endothelial cells on a collagen matrix. After 21 d in culture, the endothelial cell monolayer displayed in vivo-like intercellular borders and junctions, deposited a single-layered, continuous basement membrane that was impenetrable to colloidal particles, and supported neutrophil extravasation in a physiologic manner. Using this model, we demonstrate that neutrophil transmigration in a plasma milieu was associated with a significant disruption of the retentive properties of the basement membrane in the absence of discernable morphologic changes. The loss of basement membrane integrity associated with neutrophil diapedesis was not dependent on neutrophil elastase or cathepsin G and was resistant to inhibitors directed against neutrophil collagenase, gelatinase, and heparanase. Despite the fact that this loss in matrix integrity could not be prevented, basement membrane defects were only transiently expressed before they were repaired by the overlying endothelium via a mechanism that required active protein and RNA synthesis. These data indicate that neutrophil extravasation and reversible basement membrane disruption are coordinated events that occur as a consequence of vessel wall transmigration.

Basement Membrane↗
PubMedDate not supplied

Assessment of renal function in renal transplant patients using cystatin C. A comparison to other renal function markers and estimates.

To date, little evidence is available to define the role of cystatin C in patients with renal transplants. Thus, to assess, whether cystatin C (CysC) provides better information on renal function than other markers, CysC, creatinine clearance (CrCl), serum creatinine (SCr), beta2-microglobulin (beta2-M), and 125I-Iothalamate clearance were determined in 30 patients. Correlation and ROC curves were obtained and characteristics like sensitivity and specificity were calculated. Further, to evaluate the usefulness of these markers for monitoring, intraindividual coefficients of variation for CysC and SCr measurements were compared in 85 renal transplant patients. CysC correlated best with GFR, whereas SCr, CrCl and beta2-M all had lower correlation coefficients. CysC was superior to SCr, even when renal function equations of were used. The diagnostic accuracy of CysC was significantly better than SCr. but did not differ significantly from CrCl and beta2-M. Together, our data show that in patients with renal transplants, CysC has a similar diagnostic value as CrCl. However, it is superior to determinations of SCr. The intraindividual variation of CysC is significantly greater than that of SCr. This might be due to better ability of CysC to reflect temporary changes especially in mildly impaired GFR, most critical for early detection of rejection and other function impairment. In conclusion, CysC allows for easy and accurate assessment of renal function (GFR) in steady state renal transplant patients and is clearly superior to the commonly used serum creatinine.

Adult↗
PubMedDate not supplied

[Hereditary diseases of erythrocyte membrane: from clinical aspects to underlying genetical and molecular mechanisms].

During the past years many studies on erythrocyte membrane structure and function have allowed for exponential development of this field. Inborn errors of red cell membrane include a variety of disorders characterized by alterations of the membrane skeleton or other membrane proteins. Most recently, many studies have been published using methods from molecular biology allowing for clarification of genotype phenotype relationship. This review outlines in details clinical aspects and organisational consequences of defects molecules of membrane proteins and skeleton and their contributions to the pathophysiology of hemolytic anaemia.

Anemia, Hemolytic, Congenital↗