RESUMEN
AIM OF THE STUDY: To investigate the expression of three inflammation markers, HLA-DR, IL-6, and IL-8, by conjunctival epithelial cells obtained using impression cytology (IC) samples from long-term treated glaucoma patients. PATIENTS AND METHODS: IC samples were obtained from the 60 following individuals: 45 patients suffering from primary open-angle glaucoma and receiving topical treatments for at least 1 year and 15 subjects with no ophthalmological disease (controls). Membrane expression of HLA-DR and intracellular expression of IL-6 and IL-8 were quantified, respectively, by indirect and direct immunofluorescence techniques. Fluorescence levels were quantified using calibrated fluorescent beads. RESULTS: The percentage of HLA-DR-positive cells was significantly higher on IC samples from multitreated glaucoma patients and from patients treated by either preserved betablocker or preserved prostaglandin analogue than on IC samples from control individuals. Interestingly, the percentage of HLA-DR-positive cells was not significantly increased upon treatment with unpreserved betablocker. However, the percentage of IL-6- and IL-8-positive cells as well as IL-6 and IL-8 expression levels was significantly higher in patients than in controls, regardless of the treatment type and the presence of preservative. A significant positive correlation was found between HLA-DR and cytoplasmic IL-6 expression, between HLA-DR and cytoplasmic IL-8 as well as between IL-6 and IL-8 cytoplasmic expressions. CONCLUSION: The present study confirms that there is an increased expression of HLA-DR in treated glaucoma patients compared to controls and demonstrates that antiglaucoma treatments lead to increased IL-6 and IL-8 expressions. It also indicates that benzalkonium-preserved eyedrops and preserved multitherapy may induce stronger inflammatory responses than do unpreserved eyedrops, although further studies are needed to determine the respective inflammatory role of preservative and therapeutic molecules. In this study, flow cytometry was used to detect the intracellular pro-inflammatory cytokines in conjunctival cells obtained by impression cytology. This standardized and reliable technique was a useful tool to assess inflammatory and allergic ocular surface disorders.
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Conjuntiva/efectos de los fármacos , Conjuntiva/inmunología , Glaucoma/tratamiento farmacológico , Antígenos HLA-DR/análisis , Interleucina-6/análisis , Interleucina-8/análisis , Antagonistas Adrenérgicos beta/administración & dosificación , Antagonistas Adrenérgicos beta/farmacología , Compuestos de Benzalconio/farmacología , Inhibidores de Anhidrasa Carbónica/administración & dosificación , Inhibidores de Anhidrasa Carbónica/farmacología , Conjuntiva/citología , Técnicas Citológicas , Citoplasma , Interpretación Estadística de Datos , Células Epiteliales/efectos de los fármacos , Células Epiteliales/inmunología , Femenino , Citometría de Flujo , Técnica del Anticuerpo Fluorescente Directa , Técnica del Anticuerpo Fluorescente Indirecta , Glaucoma de Ángulo Abierto , Humanos , Masculino , Soluciones Oftálmicas , Conservadores Farmacéuticos/farmacología , Prostaglandinas/administración & dosificación , Prostaglandinas/farmacología , Factores de TiempoRESUMEN
BACKGROUND: Recent decades have been marked by an increasing number of patients suffering from ocular allergic-like symptoms without being associated with an increase in IgE levels. These symptoms include heaviness of the lid, foreign body sensation, burning, stinging and photophobia. Both epidemiological studies and controlled human exposure clinical studies have shown cause-effect relationships between allergic-like symptoms and environmental factors such as outdoor air pollutants or poor indoor air quality. An ocular surface subclinical inflammation is thought to be responsible for pseudoallergic, pollution-related conjunctivitis. The complement system is considered as one of the major effector mechanisms involved in initiation of the subclinical inflammation that leads to IgE-independent eye irritation. PURPOSE: To study the capability of nine antiallergic eyedrops commonly used in the treatment of allergic conjunctivitis to inhibit complement activation induced in vitro by pollutants. METHODS: Normal human serum obtained from healthy individuals was used as a source of complement. Activation of complement was assessed using the complement hemolytic 50% (CH50) assay, in the absence or the presence of antiallergic eyedrops and in the absence or the presence of various stimuli, including sand, common house dust, eye mascara, and Dactylis glomerata pollen extract. Zymosan was used as a standardized complement activator. The following eyedrops were studied: Naabak (4.9% N-acetyl aspartic acid-glutamic acid, NAAGA, sodium salt), Almide (lodoxamide 0.1%), Levophta (0.05% levocabastine), Emadine (0.05% emedastine), Tilavist (2% nedocromil), Allergodil (0.05% azelastine), Patanol (olopatadine), and Zaditen (0.025% ketotifen). Effects of preservative-free lodoxamide and ketotifen were also assessed and compared to those of the preserved formulations. A solution of 0.01% benzalkonium chloride (BAC), the most widely used preservative in topical eyedrops, was also tested. RESULTS: Zymosan-induced activation of complement (30+/-6%) was significantly lowered by preincubation of serum with unpreserved NAAGA (16.6+/-4%, p=0.0026) or benzalkonium-preserved nedocromil (20+/-2%, p=0.022). Preserved levocabastine, emedastine, olopatadine and ketotifen did not interfere with zymosan-induced complement activation, whereas preserved azelastine, lodoxamide and benzalkonium chloride significantly aggravated complement activation induced by zymosan. Similar results were obtained when complement activation was triggered by sand, common house dust, mascara, or by an allergenic extract of Dactylis glomerata pollen. In the absence of complement activator, none of the antiallergic eyedrops induced a significant change in CH50 titer, indicating that the deleterious pro-inflammatory effect of preserved azelastine and lodoxamide may occur only once complement activation has been initiated, i.e., on an inflamed ocular surface. CONCLUSION: Among the antiallergic eyedrops tested in this study, only Naabak and Tilavist were found to significantly inhibit complement activation triggered by particulate matters or pollen allergenic extract. Such an anticomplement activity confers these two molecules a potential in the therapeutic management of pollution-related pseudoallergic conjunctivitis.
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Contaminantes Atmosféricos/efectos adversos , Antialérgicos/farmacología , Activación de Complemento/efectos de los fármacos , Conjuntivitis/tratamiento farmacológico , Soluciones Oftálmicas/farmacología , Ácido Oxámico/análogos & derivados , Compuestos de Benzalconio/farmacología , Bencimidazoles/farmacología , Conjuntivitis/etiología , Conjuntivitis/inmunología , Cosméticos , Dibenzoxepinas/farmacología , Dipéptidos/farmacología , Evaluación de Medicamentos , Polvo , Humanos , Técnicas In Vitro , Cetotifen/farmacología , Nedocromil/farmacología , Clorhidrato de Olopatadina , Ácido Oxámico/farmacología , Ftalazinas/farmacología , Piperidinas/farmacología , Polen , Dióxido de Silicio , Zimosan/farmacologíaRESUMEN
PURPOSE: Trabecular meshwork, which is involved in aqueous outflow resistance, is deeply modified in glaucoma patients, with a decrease in the trabecular cell number. Trabecular toxicity of antiglaucoma medications cannot be excluded. On a human cultured trabecular cell line, we investigated the potential proapoptotic effect of a beta-blocker with or without preservative, benzalkonium chloride (0.01% BAC), by flow cytometry and confocal microscopy. MATERIAL: and METHODS: A human immortalized trabecular cell line (HTM-5) obtained from a normal donor was cultured under normal conditions. Preserved 0.25% betaxolol suspension (betaxolol BAC +), unpreserved 0.25% betaxolol suspension, and 0.01% BAC were respectively added to the culture medium in a 1/10 or 1/100 dilution for 15 minutes. After a 24-hour recovery period in normal culture conditions, cell size and the expression of an apoptotic marker, Apo 2.7, were evaluated by flow cytometry and confocal microscopy. Untreated trabecular cells were used as control cells. RESULTS: Preserved and unpreserved betaxolol in a 1/10 dilution induced a significant decrease in trabecular cell size compared to controls. However, this cell size decrease was less pronounced than that induced by BAC at the same dilution. Similar results were obtained with betaxolol and BAC in a 1/100 dilution. Trabecular cell Apo 2.7 expression was significantly increased after treatment with betaxolol BAC + and BAC- in a 1/10 dilution compared to controls (36.8%, 28.1%, and 15.4%, respectively p<0.005). However, this proapoptotic activity was much less pronounced than that induced by BAC- at the same dilution (96.9%, p<10(-4)). Unpreserved betaxolol in a 1/100 dilution had no apoptotic activity on trabecular cells. Trabecular cell Apo 2.7 expression slightly increased with betaxolol BAC + at a 1/100 dilution (24.9%, p=0.04), while it was greatly increased with BAC at the same dilution (39.9%; p<10(-4)). CONCLUSION: In our model, unpreserved betaxolol at a low concentration displayed no proapoptotic activity on trabecular cells. On the other hand, preserved betaxolol displayed a moderate proapoptotic activity by triggering cell death of around 25% of cells. Trabecular cell toxicity appeared to be mainly due to the preservative benzalkonium chloride (BAC). Taken together, our results demonstrated that the strong apoptotic activity of BAC was greatly reduced within the preserved eye drops, probably through the interaction of BAC with the active compound.
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Antagonistas Adrenérgicos beta/farmacología , Apoptosis , Compuestos de Benzalconio/farmacología , Betaxolol/farmacología , Soluciones Oftálmicas , Conservadores Farmacéuticos/farmacología , Malla Trabecular/citología , Malla Trabecular/efectos de los fármacos , Muerte Celular , Línea Celular , Tamaño de la Célula , Medios de Cultivo , Citometría de Flujo , Humanos , Microscopía Confocal , Factores de TiempoRESUMEN
BACKGROUND: Cell adhesion plays a pivotal role in most ocular surface inflammatory diseases. Adhesion molecules mediate cell-to-cell and cell-to-matrix adhesion. Their expression is up-regulated by pro-inflammatory stimuli such as cytokines, histamine or complement-derived anaphylatoxins. The dipeptide N acetyl-aspartyl glutamic acid (NAAGA) is used as unpreserved topical eyedrops in the treatment of allergic conjunctivitis. NAAGA is known to inhibit leukotriene synthesis, histamine release by mast cells, and complement-derived anaphylatoxin production. PURPOSE: To investigate the potential capability of NAAGA to interfere with leukocyte adhesion to endothelial cells and modulate cytokine-induced expression of adhesion molecules. METHODS: Human blood-derived leukocytes were co-cultured with human umbilical vein endothelial cells (HUVECs) in the absence or the presence of 1000 UI/mL human recombinant TNFalpha, 10(-4) M histamine di-hydrochloride or 5x10(-6) M human recombinant C5a, and in the absence or presence of NAAGA (final concentration 2.45%). Adhesion of leukocytes to HUVECs was calculated by subtracting the number of nonadherent leukocytes from the total number of leukocytes. Expression of adhesion molecules was assessed by flow cytometry using anti-CD11b, anti-CD49d, anti-ICAM-1 (CD54), anti-ICAM-2 (CD102), anti-VCAM-1 (CD106) and anti-ELAM-1 (CD62E) monoclonal antibodies. RESULTS: NAAGA was found to totally inhibit adhesion of unstimulated leukocytes, or leukocytes activated with C5a, TNFalpha, or histamine, to TNFalpha-stimulated HUVECs (P=0.0001). Adhesion of leukocytes to unstimulated HUVECs was not modified by NAAGA. Similar results were obtained with endothelial cells stimulated by histamine or C5a. Taken together, these data indicate that NAAGA totally abrogates cell adhesion under inflammatory conditions, without interfering with the physiological adhesion of leukocytes to normal endothelium. At the molecular level, NAAGA inhibited histamine-induced expression of CD11b (P=0.0004) and CD49d (P=0.0045) on granulocytes. On TNFalpha-activated HUVECs, NAAGA induced a significant decrease in the VCAM-1 expression level (P<0.0001) and totally reversed TNFalpha-induced overexpression of ICAM-1 (P=0.0069), ICAM-2 and ELAM-1 (P<0.0001), without interfering with baseline expression of these molecules. CONCLUSION: These results show that the antiallergic compound NAAGA directly inhibits leukocyte adhesion to endothelial cells induced by pro-inflammatory stimuli, and abrogates TNFalpha-induced expression of adhesion molecules on granulocytes and endothelial cells. This capacity to block overexpression of selectins and integrins induced by pro-inflammatory stimuli confers to NAAGA a potential as an anti-inflammatory drug, since interfering with adhesion molecule expression is probably one of the most efficient ways to curb leukocyte recruitment to inflammatory sites.
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Dipéptidos/farmacología , Endotelio/citología , Endotelio/fisiología , Leucocitos/efectos de los fármacos , Leucocitos/fisiología , Antígenos CD/biosíntesis , Antígeno CD11b/biosíntesis , Adhesión Celular/efectos de los fármacos , Moléculas de Adhesión Celular/biosíntesis , Células Cultivadas , Selectina E/biosíntesis , Humanos , Integrina alfa4/biosíntesis , Molécula 1 de Adhesión Intercelular/biosíntesis , Molécula 1 de Adhesión Celular Vascular/biosíntesisRESUMEN
Carbohydrate structures are involved in numerous biological activities such as inflammation, and cell adhesion/migration/proliferation. This gives the rationale for the design of vascular targeted drug delivery systems bearing sugar moieties. For the imaging and treatment of vascular diseases, an overview is presented with polysaccharides targeting vascular components. After a general description of the vasculature and the main blood components, a special emphasis is placed on carbohydrate-based molecules, such as heparin/heparan sulfate, and carbohydrate-binding proteins, such as selectins found in the vascular system. The methods using heparin and heparin analogs in delivery systems applied to vascular components are then described.
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Endotelio Vascular/efectos de los fármacos , Polisacáridos/farmacología , Animales , Secuencia de Carbohidratos , Endotelio Vascular/citología , Humanos , Datos de Secuencia MolecularRESUMEN
Plasma levels of proinflammatory cytokines, cytokine inhibitors, and the beta chemokines RANTES, macrophage inhibitory protein (MIP)-1alpha, and monocyte chemoattractant protein (MCP)-1 were studied in relationship with virus load in 40 patients exhibiting plasma levels of HIV RNA ranging between undetectable and levels >10(6) copies/mL. Mean plasma levels of MCP-1 were increased in patients with high virus load compared with HIV-seropositive subjects with undetectable plasma viral RNA and healthy controls. MCP-1 levels were directly correlated with plasma levels of HIV RNA. No correlation was observed between virus load and plasma concentrations of MIP-1alpha and RANTES. The results suggest that low rates of viral replication in vivo are not dependent on increased production of the suppressive chemokines RANTES and MIP-1alpha. Since MCP-1 upregulates viral replication in vitro, the results may suggest a role for MCP-1 in triggering viral replication in HIV disease.
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Quimiocina CCL2/sangre , Quimiocina CCL5/sangre , Infecciones por VIH/inmunología , Infecciones por VIH/virología , VIH/fisiología , Proteínas Inflamatorias de Macrófagos/sangre , Carga Viral , Quimiocina CCL3 , Quimiocina CCL4 , Citocinas/sangre , Infecciones por VIH/sangre , Humanos , Proteína Antagonista del Receptor de Interleucina 1 , Receptores de Lipopolisacáridos/sangre , ARN Viral/sangre , Receptores de Interleucina-1/antagonistas & inhibidores , Receptores del Factor de Necrosis Tumoral/sangre , Sialoglicoproteínas/sangre , Replicación ViralAsunto(s)
Sangre , Activación de Complemento/efectos de los fármacos , Endotelio Vascular/fisiología , Polisacáridos/farmacología , Animales , Células Cultivadas , Chlorophyta , Proteínas del Sistema Complemento/biosíntesis , Proteínas del Sistema Complemento/fisiología , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Humanos , Polisacáridos/aislamiento & purificación , Algas Marinas , Porcinos , Trasplante HeterólogoRESUMEN
Using flow cytometry we have compared the binding of Neisseria meningitidis lipopolysaccharide labeled with fluorescein isothiocyanate (FITC-LPS) to normal human monocytes in whole blood with the binding to chinese hamster ovary (CHO) cells transfected with human CD14 gene (hCD14-CHO cells). Binding of FITC-LPS to cells was dose dependent, saturable and enhanced in the presence of increasing concentrations of serum. Blockade of membrane CD14 with saturating concentrations of anti-CD14 monoclonal antibody (mAb) My4 inhibited 50% of the binding of FITC-LPS to monocytes and 100% to hCD14-CHO cells. Similarly, removal of membrane CD14 by phosphatidylinositol phospholipase C (PI-PLC) treatment of the cells partially decreased the binding of FITC-LPS to monocytes but totally inhibited the binding to hCD14-CHO-transfected cells. These results suggest that binding of FITC-LPS to monocytes is not only mediated by membrane CD14. Using two-color flow cytometry, we observed that FITC-LPS binds to My4-saturated monocytes in association with soluble (s)CD14 present in serum as revealed by staining with rhodamine-labeled My4 mAb. The binding of FITC-LPS/sCD14 complexes to monocytes treated with saturating amounts of unlabeled My4 prior to addition of the complexes was completely inhibited by anti-CD14 mAb 10G33. When cells were first saturated with a mixture of My4 and 10G33 mAb, washed and further incubated with FITC-LPS/sCD14, inhibition of the binding of LPS was similar to that observed with cells saturated with My4 alone, showing that the binding of FITC-LPS is not mediated by the 10G33 epitope present on mCD14. These results suggest that either the 10G33 epitope on sCD14 is involved in the binding of LPS/sCD14 complexes to the cells, or that 10G33 mAb inhibits the binding of FITC-LPS to sCD14. Taken together, these data indicate that sCD14 which is present in normal serum, in addition to membrane CD14, enables LPS to bind monocytes through an as yet unidentified molecule and that sCD14 does not simply serve as a shuttle for transfer of LPS to membrane CD14.
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Receptores de Lipopolisacáridos/inmunología , Lipopolisacáridos/inmunología , Monocitos/inmunología , Animales , Células CHO , Cricetinae , Humanos , Receptores de Lipopolisacáridos/metabolismo , Lipopolisacáridos/metabolismo , Monocitos/metabolismo , Receptores Inmunológicos/inmunología , Receptores Inmunológicos/metabolismoAsunto(s)
Anticoagulantes/aislamiento & purificación , Polisacáridos/química , Algas Marinas/química , Anticoagulantes/farmacología , Cromatografía por Intercambio Iónico , Electroforesis en Acetato de Celulosa , Fucosa/análisis , Glucuronatos/análisis , Ácido Glucurónico , Peso Molecular , Tiempo de Tromboplastina Parcial , Polisacáridos/aislamiento & purificación , Polisacáridos/farmacología , Sulfatos/análisisRESUMEN
We have shown previously that a low-molecular-weight fucan extracted from the brown seaweed Ascophylum nodosum strongly inhibited human complement activation in vitro and its mechanism of action was largely elucidated. We further investigated the influence of molecular weight and chemical composition of fucan on its anticomplementary activity. The capacity of 12 fragments of fucan (ranging from a molecular weight of 4100 to 214,000) to prevent complement-mediated haemolysis of sheep erythrocytes (classical pathway) and of rabbit erythrocytes (alternative pathway) increased with increasing molecular weight, and reached a plateau for 40,000 and 13,500, respectively. The most potent fucan fractions were 40-fold more active than heparin in inhibiting the classical pathway. They were, however, as active as heparin in inhibiting the alternative pathway. In addition, we have developed a haemolytic test based on the CH50 protocol, which allows discrimination between activators and inhibitors of complement proteins. Although the mannose content within the different fucan fragments did not vary, the galactose and glucuronic acid contents increased with increasing activity, suggesting that these residues should be essential for full anticomplementary activity. Meanwhile, sulphate groups appeared to be necessary, but were clearly not a sufficient requirement for anticomplementary activity of fucans. Taken together, these data illustrate the prospects for the use of fucans as potential anti-inflammatory agents.
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Antineoplásicos/farmacología , Activación de Complemento/efectos de los fármacos , Polisacáridos/farmacología , Ésteres del Ácido Sulfúrico/farmacología , Animales , Antineoplásicos/química , Cromatografía de Gases , Ensayo de Actividad Hemolítica de Complemento , Eritrocitos/citología , Eritrocitos/efectos de los fármacos , Fucosa/metabolismo , Galactosa/metabolismo , Glucuronatos/metabolismo , Ácido Glucurónico , Hemólisis/efectos de los fármacos , Humanos , Manosa/metabolismo , Peso Molecular , Polisacáridos/química , Conejos , Ovinos , Relación Estructura-Actividad , Ésteres del Ácido Sulfúrico/química , Xilosa/metabolismoRESUMEN
The pyrH gene, encoding UMP-kinase from Escherichia coli, was cloned using as a genetic probe the property of the carAB operon to be controlled for its expression by the concentration of cytoplasmic UTP. The open reading frame of the pyrH gene of 723 bp was found to be identical to that of the smbA gene [Yamanaka, K., et al. (1992) J. Bacteriol. 174, 7517-7526], previously described as being involved in chromosome partitioning in E. coli. The bacterial UMP-kinase did not display significant sequence similarity to known nucleoside monophosphate kinases. On the contrary, it exhibited similarity with three families of enzymes including aspartokinases, glutamate kinases, and Pseudomonas aeruginosa carbamate kinase. UMP-kinase overproduced in E. coli was purified to homogeneity and analyzed for its structural and catalytic properties. The protein consists of six identical subunits, each of 240 amino acid residues (the N-terminal methionine residue is missing in the expressed protein). Upon excitation at 295 nm, the bacterial enzyme exhibits a fluorescence emission spectrum with maximum at 332 nm which indicates that the single tryptophan residue of the protein (Trp119) is located in a hydrophobic environment. Like other enzymes involved in the de novo synthesis of pyrimidine nucleotides, UMP-kinase of E. coli is subject to regulation by nucleotides: GTP is an allosteric activator, whereas UTP serves as an allosteric inhibitor. UTP and UDP, but none of the other nucleotides tested such as GTP, ATP, and UMP, enhanced the fluorescence of the protein. The sigmoidal shape of the dose-response curve indicated cooperativity in binding of UTP and UDP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Escherichia coli/enzimología , Nucleótidos de Guanina/metabolismo , Nucleósido-Fosfato Quinasa/química , Nucleósido-Fosfato Quinasa/metabolismo , Uridina Trifosfato/metabolismo , Secuencia de Aminoácidos , Aspartato Quinasa , Secuencia de Bases , Clonación Molecular , Estabilidad de Enzimas , Escherichia coli/genética , Guanosina Trifosfato/análogos & derivados , Guanosina Trifosfato/metabolismo , Cinética , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Nucleósido-Fosfato Quinasa/aislamiento & purificación , Filogenia , Espectrometría de FluorescenciaRESUMEN
In the present study, we demonstrate that natural sulfated polysaccharides (fucans) isolated from brown seaweed are potent inhibitors of human complement activation. A fucan fraction of chromatographic molecular weight 22,600, termed BS8, was found to inhibit classical and alternative pathway activation in whole serum in a dose-dependent fashion. Fucan BS8 inhibited formation of the classical pathway C3 convertase by interfering with C1 activation or by inhibiting C4 cleavage and the interaction between C4b and C2. The fucan also inhibited formation/function of the alternative pathway C3 convertase by suppressing the binding of B to C3b and by interfering with the stabilizing function of Properdin. The inhibitory effect of fucans on formation of the C3 convertases was dependent on the molecular weight of the polysaccharide for compounds of chromatographic molecular weight below 16,600. Fucan had no effect on the function of the terminal complex. Since fucans were more efficient than heparin in inhibiting activation of the classical pathway in whole serum and exhibited a lesser specific anticoagulant activity on a molar basis, our results suggest that these natural sulfated polysaccharides have a potential for use as anti-complementary and anti-inflammatory agents.
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Activación de Complemento/efectos de los fármacos , Phaeophyceae/química , Polisacáridos/farmacología , Complemento C2/biosíntesis , Complemento C2b , Convertasas de Complemento C3-C5/metabolismo , Complemento C3b/biosíntesis , Complemento C4/metabolismo , Complemento C4b/biosíntesis , Vía Alternativa del Complemento/efectos de los fármacos , Vía Clásica del Complemento/efectos de los fármacos , Relación Dosis-Respuesta a Droga , HumanosRESUMEN
Norfloxacin, a "second generation" compound of the quinolone group, was administered orally, before surgery, every 12 h during successive three-day periods at dose of 400 mg to ten patients hospitalized for prostatic adenoma or for prostatic cancer. On the day of surgery, a 400 mg-last dose was administered. Unchanged norfloxacin was assayed by high performance liquid chromatography with fluorescence detection. The Cmin value was 1.2 +/- 0.77 mg/l. Concurrent norfloxacin concentrations in plasma and epididymal tissue (left and right) were determined, about 4 h after the last drug intake, the epididymal level was 3.4 +/- 1.9 micrograms/g. This value was above the MIC90 for most sensitive organisms. The ratio (+/- SD) of drug concentration in epididymal tissue and in plasma was 3. 74 +/- 2.10 (range 1.66-10.2). The epididymal level of norfloxacin was strongly correlated with, area under curve (p less than 0.001) and plasma concentration (p less than 0.01).