Synthesis, physicochemical characterization, and biological evaluation of 2-(1'-hydroxyalkyl)-3-hydroxypyridin-4-ones: novel iron chelators with enhanced pFe(3+) values

The synthesis of a range of 2-(1'-hydroxyalkyl)-3-hydroxypyridin-4-ones as bidentate iron(III) chelators with potential for oral administration is described. The pK(a) values of the ligands and the stability constants of their iron(III) complexes have been determined. Results indicate that the introduction of a 1'-hydroxyalkyl group at the 2-position leads to a significant improvement in the pFe(3+) values. Such an effect was found to be greater with the hydroxyethyl substituent than with the hydroxymethyl substituent, particularly in the cases of 1-ethyl-2-(1'-hydroxyethyl)-3-hydroxypyridin-4-one (pFe(3+) = 21.4) and 1,6-dimethyl-2-(1'-hydroxyethyl)-3-hydroxypyridin-4-one (pFe(3+) = 21.5) where an enhancement on pFe(3+) values in the region of two orders of magnitude is observed, as compared with Deferiprone (1, 2-dimethyl-3-hydroxypyridin-4-one) (pFe(3+) = 19.4). The ability of these novel 3-hydroxypyridin-4-ones to facilitate the iron excretion in bile was investigated using a [(59)Fe]ferritin-loaded rat model. Chelators and prodrug chelators possessing high pFe(3+) values show great promise in their ability to remove iron under in vivo conditions.

An important role of actin polymerization in the human zona pellucida-induced acrosome reaction

The effects of inhibitors of actin polymerization and depolymerization, cytochalasins and phalloidin, on the human zona pellucida (ZP)-induced acrosome reaction (AR) were investigated. Motile spermatozoa, selected by swim-up technique from normozoospermic men, were incubated in medium with or without the actin modulators. Oocytes (four per test) which had failed to fertilize in vitro were added and incubation continued for 2 h. The spermatozoa bound to the ZP were dislodged by repeatedly aspirating the oocytes with a small-bore pipette and the status of the acrosomes was determined by fluorescein-labelled Pisum sativum agglutinin (PSA). Double immunofluorescent staining with PSA and an anti-actin monoclonal antibody illuminated the acrosomal region of acrosome-intact spermatozoa. In calcium ionophore-induced AR spermatozoa, actin staining was confined to the equatorial segment, post-acrosomal region and tail. Cytochalasins B and D significantly inhibited ZP-induced AR in a dose-dependent manner (P < 0.001). Both inhibitors had no effect on the acrosome of spermatozoa in the insemination medium. Cytochalasin B or D (10-40 micromol/l) had no effect on total percentage motile spermatozoa but decreased sperm velocity and hyperactivation. Phalloidin had no effect on the ZP-induced AR or sperm motility. In conclusion, actin polymerization plays an important role in human ZP-induced AR.

Gradient ion-pair high-performance liquid chromatographic method for analysis of 3-hydroxypyridin-4-one iron chelators

A gradient ion-pair HPLC separation of highly hydrophilic 3-hydroxypyridin-4-one (HPO) iron chelators is described. The separation of HPOs was performed using a reversed-phase polymer HPLC column (PLRP-S 100 A, 15x0.46 cm ID, 5 microm). The ion-pair buffer contained 1-heptanesulfonic acid (sodium salt) (5 mM) and the pH was adjusted to 2.0 using HCl. The gradient was 2%-35% CH3CN in 20 min and post-run was followed for 5 min using 2% CH3CN and 98% buffer. The flow-rate was 1 ml/min and the analytes were monitored at 280 nm. The retention times of 30 hydrophilic HPOs fell in the range of 10-18 min with sharp peak shapes, although these iron chelators possess various functional groups and distribution coefficients. The application of this HPLC method in the analysis of HPO chelators and their metabolites in rat bile and urine is described.

Synthesis, physicochemical properties and biological evaluation of aromatic ester prodrugs of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one (CP102): orally active iron chelators with clinical potential

The synthesis of seven aromatic ester derivatives of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one is described. These ester prodrugs have been designed to target iron chelators to the liver, the major iron storage organ. In principle this should improve chelation efficacy and minimize toxicity. The distribution coefficients of these ester prodrugs between 1-octanol and MOPS buffer pH 7.4 were measured together with their rates of hydrolysis at pH 2 and pH 7.4, in rat blood and liver homogenate. Esters with heteroaromatic acid moieties were found to be less stable than benzoyl analogues. The in-vivo iron mobilisation efficacy of these ester prodrugs has been compared with that of the parent drug using a 59Fe-ferritin loaded rat model. Many prodrugs were found to enhance the ability of the parent hydroxypyridinone to facilitate 59Fe excretion. However, not all prodrugs provided increased efficacy, demonstrating that lipophilicity is not the only factor which influences drug efficacy. Furthermore, no clear correlation between efficacy and susceptibility to hydrolysis was detected. The picolinic and nicotinic ester derivatives appear to offer the best potential as prodrugs as they have a relatively low LogP value and yet lead to enhanced efficacy over the parent hydroxypyridinone.

Induction and inhibition of the in vitro N1-oxidation of 9-benzyladenine and isomeric 9-(nitrobenzyl)adenines

The present study investigated some aspects of the enzymology of the in vitro N1-oxidation of 9-benzyladenine (BA) and isomeric 9-(nitrobenzyl)adenines (NBAs) using various potential inducers and inhibitors of cytochrome P-450 (CYP). When incubated with phenobarbital-induced rabbit hepatic microsomes, the N1-oxidation rates of BA and 9-(4-nitrobenzyl)adenine were about 6- and 2-fold higher than that of the control, respectively; while the N1-oxidation of 9-(2-nitrobenzyl)adenine and 9-(3-nitrobenzyl)adenine was not markedly affected. In contrast, beta-naphthoflavone and Arochlor 1254 showed no inductive effects towards the N1-oxidation of any of these substrates. Using 12 typical CYP inhibitors, it was found that nifedipine (CYP3A inhibitor) and haloperidol (CYP2D inhibitor) showed significant inhibition towards the N1-oxidation of BA and NBAs. Therefore, the N1-oxidation of BA and NBAs is probably catalysed by CYP3A and CYP2D subfamilies. Furthermore, when 9-(4-nitrobenzyl)adenine was incubated with compounds which possessed a certain chemical similarity to the adenine substrate, various degrees of inhibition of N1-oxidation of 9-(4-nitrobenzyl)adenine were observed. These observations allowed a preliminary indication as to the structure-metabolism relationship of 9-substituted adenine derivatives.

The expression of vascular endothelial growth factor isoforms in cultured human endometrial stromal cells and its regulation by 17beta-oestradiol

Angiogenesis or formation of new blood vessels is required for regeneration of the endometrium after its breakdown during each menstruation. Vascular endothelial growth factor (VEGF), a family of recently discovered angiogenic factors, may be involved in the repair and growth of the endometrium. In this study reverse transcription-polymerase chain reaction (PCR) was used to confirm the presence of VEGF mRNA and restriction enzyme digestion to confirm the identity of PCR products generated from different VEGF isoforms in cultured human endometrial stromal cells. The shortest isoform, VEGF 121, was the most abundant in quiescent stromal cells. It was about one-and-a-half times that of VEGF 165. The longest isoform, VEGF 206, was not detected; only a relatively weak signal for VEGF 189 was detectable. The mRNA for VEGF increased 2-fold after stimulation by 17beta-oestradiol (10 nM) for 30 min. A further increase to 3-fold above baseline occurred after 2 h incubation and remained steady at 6 h incubation, but decreased to 2-fold of baseline after 15 h. There was no differential stimulation of mRNA for VEGF isoforms: the ratio of VEGF 121 to 165 remained constant at 3:2 during the course of the incubation, with the exception at 15 h incubation when the ratio was 2:1. The VEGF protein, determined by specific enzyme immunoassay, increased from undetectable at baseline to 79.8 +/- 18.9 pg/ml (n = 4, mean +/- SD, 9.6 cm2/well/ml) after 2 h, with a further significant increase to 249.5 +/- 27.3 pg/ml after 15 h and 695.0 +/- 41.4 pg/well after 39 h. At 15 h incubation, the specific oestradiol antagonist ICI 182,780 (1 microM) significantly reduced VEGF secretion by 25% from 249.5 +/- 27.3 to 189.0 +/- 26.6 pg/ml. Thus, VEGF showed specific patterns of isoform expression in the human endometrial stromal cells; oestradiol (10 microM) stimulated, but not differentially, the mRNA for VEGF isoforms.

Delayed administration of low-dose NPC18915 ameliorates lung ischemia-reperfusion injury

BACKGROUND

NPC18915, a member of new antiinflammatory agent called nactins (neutrophil activation inhibitors), has been shown to reduce reperfusion injury in rat lung transplantation at high dosage. In vitro studies have demonstrated effectiveness of this compound even at low dosage. We hypothesized that this compound ameliorates lung ischemia reperfusion injury even at low dosage levels if administration is optimally timed. The aim of this study was to determine the efficacy and the best timing for administration of low-dose NPC18915.

METHODS

Forty syngeneic rat left lung transplantations were performed. All isografts were flushed with low-potassium dextran-1% glucose solution 20 ml and preserved for 18 hours at 4 degrees C. Animals were divided into four groups. Group I animals (n = 10) served as control subjects. In groups II (n = 10), III (n = 10), and IV (n = 10), NPC18915 (0.04 mg) was added to the flush solution and was administered intravenously (0.4 mg/kg) immediately before reperfusion (group II) and 60 minutes (group III) and 120 minutes (group IV) after reperfusion. Pulmonary function was assessed 24 hours after reperfusion.

RESULTS

In group III, oxygenation improved in comparison to group I (247.2 +/- 59.8 versus 76.6 +/- 16.0 mm Hg, p < 0.002). Wet-to-dry weight ratio and graft myeloperoxidase activity were significantly improved (group III versus group I, 6.02 +/- 0.21 versus 7.19 +/- 0.41, p = 0.013) (group III versus group I, 0.093 +/- 0.019 versus 0.207 +/- 0.023 delta optical density/min/mg, p < 0.002). There were no significant differences in CD11b expression.

CONCLUSION

These data suggest that delayed administration of NPC18915, 60 minutes after reperfusion, dramatically improves pulmonary graft function.

Reduction of acute and reactivated colitis in rats by an inhibitor of neutrophil activation

Neutrophils have been implicated as major contributors to tissue injury in inflammatory bowel disease. In this study, we have assessed the effects of an inhibitor of neutrophil activation and adherence, NPC-18915 (4-¿2-[2-(2-benzofuranyl)phenyl]-(E)-ethenyl¿benzoic acid sodium salt), in models of both acute and reactivated colitis. Acute colitis was induced by intracolonic administration of a hapten. In other rats, colitis was reactivated 6 wk after a bout of acute colitis by subcutaneous administration of the hapten. NPC-18915 given during the first 4 days after induction of acute colitis significantly reduced tissue injury and the incidence of diarrhea and adhesions. When treatment of NPC-18915 was initiated after colitis was firmly established (48 h posthapten), it did not produce a significant effect. NPC-18915 was effective at significantly reducing colonic injury and granulocyte infiltration in the reactivated colitis model, and a similar effect could be observed in rats treated with antineutrophil serum. These results demonstrate that an inhibitor of neutrophil activation is effective in both acute and reactivated colitis, although in the former case, effectiveness is only seen when the drug is given before full establishment of colitis. These results also suggest that neutrophils, are a critical effector cell of hapten-induced colitis in the rat, particularly in the case of reactivated colitis.

Calcium ionophore-induced acrosome reaction correlates with fertilization rates in vitro in patients with teratozoospermic semen

The aim of this study was to determine the relationship between calcium ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing ability. Semen samples remaining after preparation for standard IVF were studied in 109 patients who had sperm concentrations > or =20 x 10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected by centrifugation on a Percoll gradient. Semen analysis was performed using standard methods. Patients with higher (>50%, n = 76) fertilization rates had significantly higher ionophore-induced AR than patients with lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P < 0.05). When the data from all patients were analysed by logistic regression, only the percentage sperm motility in insemination medium and ionophore-induced AR were significantly related to fertilization rates. Similar results were also obtained when the data from a subgroup of patients with poor (<15% normal) sperm morphology were analysed. However, when patients with normal sperm morphology > or =15% were analysed separately, only sperm count and the percentage of spermatozoa with progressive motility in semen were significantly related to fertilization rates. In conclusion, ionophore-induced AR was significantly related to fertilization rates in vitro mainly in patients with teratozoospermic semen. Tests for ionophore-induced AR may provide additional information about sperm fertilizing ability but may not indicate specific defects of the physiological AR.

Interleukin-1 beta induces cyclooxygenase-2 gene expression in cultured endometrial stromal cells

Increasing evidence indicates that PGs may play an obligatory role in blastocyst implantation. Cyclooxygenase (also known as PGH synthase) isozymes 1 and 2 catalyze the rate limiting steps in the biosynthesis of PGs. The ubiquitous cyclooxygenase-1 (COX-1) subserves housekeeping functions, whereas the inducible cyclooxygenase-2 (COX-2) is expressed by limited cell types and tightly controlled. Here we report the induction of COX-2 gene expression by interleukin-1 beta (IL-1 beta) in cultured human endometrial stromal cells. COX-2 activity was induced by IL-1 beta (1 ng/mL); conversion of exogenous arachidonic acid to PGF2 alpha increased from 2.6 +/- 0.6 ng/well (mean +/- SEM; n = 6) to 22.2 +/- 5.6 ng, but was completely blocked (2.8 +/- 0.7 ng/well) by NS-398, a specific COX-2 inhibitor. Undetectable in quiescent stromal cells, messenger ribonucleic acid for COX-2 was induced 30 min after IL-1 beta treatment, reached a maximum at 4 h, and decreased after 15 h. Protein synthesis was not required for induction of the COX-2 gene, as it was blocked by actinomycin D but not by cycloheximide. The 70-kDa COX-2 protein was not detected in quiescent cells, became detectable 6 h after IL-1 beta treatment, and remained detectable even after 15 h. IL-1 beta (0.1-100 ng/mL) increased the luciferase activity in promoterless luciferase reporter containing the 900-bp 5'-flanking sequence (-891 to +9) of the COX-2 gene in a dose-dependent manner, with an ED50 of 0.1-1 ng/mL.

Protein kinase C plays an important role in the human zona pellucida-induced acrosome reaction

To investigate the involvement of protein kinases in signal transduction in the human zona pellucida (ZP)-induced acrosome reaction (AR), the effects of protein kinase (PK) activators, dibutyryl cAMP (PKA) and cGMP (PKG), phorbol 12-myristate 13-acetate (PMA, PKC), and the PKC inhibitor, staurosporine were studied. Sperm samples were obtained from normozoospermic men with normal sperm-ZP binding. Oocytes were obtained from other patients with failure of fertilization in vitro. Motile spermatozoa selected by a swim-up technique were pre-incubated with 2.5-20 microM PMA, 1 mM dibutyryl cAMP or cGMP, 3 mM pentoxifylline or 0.125-2.0 microM staurosporine for 30 min and then incubated with four oocytes for 2 h in human tubal fluid supplemented with bovine serum albumin. The spermatozoa bound to the ZP were dislodged by repeatedly aspirating the oocytes with a small bore pipette and the state of the AR was determined by fluorescein-labelled Pisum sativum agglutinin. Motility and movement characteristics were assessed by computer-assisted sperm analysis (CASA) after incubation of spermatozoa with PMA for 30 min and 2 h. The dibutyryl cAMP and cGMP analogues had a small positive effect (P < 0.05) but pentoxifylline had no effect on stimulating the ZP-induced AR (P > 0.05). In contrast, PMA stimulated ZP-induced AR in a marked dose-dependent manner. Only the highest concentrations (15-20 microM) of PMA significantly decreased percentage motility (P < 0.001). Doses of 2.5-15 microM of PMA significantly stimulated ZP-induced AR without decreasing motility (P < 0.001). The PKC inhibitor, staurosporine (0.125-0.25 microM) significantly inhibited ZP-induced AR without affecting motility (P < 0.001). Sperm samples from 33 normozoospermic men were used for studies of the ZP-induced AR augmented with 15 microM PMA. One sample did not show a response to PMA stimulation. Among the 14 men with low ZP-induced AR, half had normal responses to PMA and other half had low responses to PMA. In conclusion, activation or inhibition of PKC significantly increases or decreases human ZP-induced AR suggesting that PKC plays a important role in the signal transduction pathway for the physiological AR.

Metabolism of 9-(2-chlorobenzyl)-, 9-(2-methylbenzyl)- and 9-(2-methoxybenzyl)-adenines by hamster hepatic microsomes

It was previously found that 9-benzyladenine (BA) was extensively N1-oxidised by animal hepatic microsomes; further, mononitrosubstitution in the phenyl moiety of BA significantly modified the N1-oxidation rates of the corresponding substrates. In order to establish whether the electronic nature or a steric effect of the substituents in the phenyl moiety is the reason for the modification of N1-oxidation rate, the metabolism of some 2'-substituted 9-benzyladenines, i.e. 9-(2-chlorobenzyl)adenine (2CBA), 9-(2-methyl-benzyl)adenine (2MBA) and 9-(2-methoxybenzyl)adenine (2MOBA), by hamster hepatic microsomes was studied. It was found that the N1-oxide was still the major metabolite for 2CBA. However, only minor amounts of N1-oxides were formed during microsomal incubation with 2MBA and 2MOBA. On the other hand, in spite of the higher N1-oxidation rate of 2CBA, its total biotransformation rate was slightly lower than the other two substrates. Like other 9-aralkyladenines previously studied, dealkylation occurred for all three substrates. It was also found that another two metabolites formed in significant amounts in the incubates from both 2MBA and 2MOBA. These metabolites were not fully characterised and their structures unknown.

The role of CD11b/CD18 mediated neutrophil adhesion in complement deficient xenograft recipients

Hyperacute rejection (HAR) of discordant xenografts is dependent on local complement activation. The formation of a functional complex of the complement components C5b-9 (membrane attack complex, MAC) causes endothelial injury and activation leading to coagulation and inflammation. In PVG rats which selectively lack the C6 component of complement, the MAC complex is not formed, whereas early split products of the complement cascade are produced normally. We reported previously that HAR is averted in C6 deficient xenograft recipients, and that subsequent accelerated acute rejection (AAR) can be delayed by inhibition of CD11b/CD18 (Mac-1) dependent neutrophil adhesion using leumedin, a member of a novel class of anti-inflammatory agents. Here we report the in vivo effects of a dose-response study using 2 new members of another class of Mac-1 directed agents designated nactins. Discordant cardiac xenografts from Hartley guinea pigs were heterotopically grafted into PVG(C6-) and PVG(C6+) rats. Experimental animals were divided into 3 groups receiving leumedin (group 1) or nactin (groups 2 and 3). Control animals received intravenous saline solution only. All C6(+) rats rejected their grafts hyperacutely within 10 to 15 min, irrespective of mode or dosage of treatment. C6 deficient controls rejected grafts within 17.7 +/- 3.5 h (n = 10). Treatment with leumedin/nactin prolonged graft survival up to 61.0 +/- 4.7 h (n = 4-6), with dose dependent differences in effectiveness among the 3 compounds tested. Histology showed that treatment was associated with less edema, hemorrhage, and neutrophil infiltrate at 2, 6, and 12 h. The marked decrease in hemorrhage seen in nactin-treated animals may reflect an interaction of Mac-1 with blood coagulation factors. Our data confirm that the neutrophil adhesion pathway is involved in AAR, especially when complement mediated injury due to MAC is restricted.

Studies on the relationship between in vitro metabolism and certain physicochemical characteristics of some 9-alkyl-/9-aralkyl adenines

Previous studies demonstrated that biological N1-oxidation occurred for some 9-alkyl-/9-aralkyladenines, but not for others, when mammalian hepatic microsomal incubates were used as enzyme source. In order to understand the mechanisms controlling the metabolic fate of these compounds, the relationship between N1-oxidation and certain physicochemical characteristics of these substrates was studied. It was found that there was no marked link between N1-oxidation and the computer predicted pKa values of the substances studied. However, a computer predicted LogP value in the range 1.3-4 seems to be the most favourable for N1-oxidation. The 1H-NMR and 13C-NMR spectroscopic characteristics of the substrates, which reflect certain electronic characteristics of the purine moiety, also showed a correlation with their N1-oxidation. The electronic effects of the substrates in relation to their metabolism was investigated using computer modelling techniques; the results showed that different substituents at the 9-position of adenine may modify the electronic characteristics of the purine moiety thus affecting their metabolism. The conformation of the substrates may also be an important controlling factor for their N1-oxidative metabolism.

Human intestinal permeability of piroxicam, propranolol, phenylalanine, and PEG 400 determined by jejunal perfusion

PURPOSE

To determine the human jejunal permeabilities of compounds utilizing different transport mechanisms using a regional perfusion approach and to establish a standard procedure for determining drug permeability class to be used for the establishment of drug product bioequivalence standards.

METHODS

Six healthy male volunteers participated in this study. A multi-lumen perfusion tube was inserted orally and positioned in the proximal region of the jejunum. A solution containing piroxicam, phenylalanine, propranolol, PEG 400 and PEG 4000 was perfused through the intestinal segment at a rate of 3.0 ml/min. Perfusate samples were quantitatively collected every 10 minutes for two 100 minute periods with an intermediate wash out period to determine intra and intersubject variation.

RESULTS

The mean P(eff) (+/-SD) of piroxicam, phenylalanine, propranolol, and PEG 400 were 10.40 +/- 5.93, 6.67 +/- 3.42, 3.59 +/- 1.60, 0.80 0.46 x 10(-4) cm/sec, respectively. The coefficient of variation for the intersubject variability, first and second perfusion periods were: piroxicam, 60.5% and 57.1%; phenylalanine, 52.8% and 57.8%; propranolol, 62.1% and 44.6%; and PEG 400, 81.7% and 42.3%, indicating a slightly lower CV for the second perfusion period in the same subject. The intrasubject CV's between the two perfusion periods were: 19.4%, 21.3%, 23.6% and 41.0% respectively, indicating a smaller intraindividual variation for all compounds studied.

CONCLUSIONS

Piroxicam, a nonpolar drug exhibited the highest permeability of the compounds studied. The intrasubject CV was lower than the intersubject CV, indicating consistent permeability estimation within subjects. The methodology is useful for permeability estimation regardless of absorption mechanism and can be used to establish a consistent data base of human permeabilities for estimation of human drug absorption and for establishing the biopharmaceutic permeability class of drugs.

Solid phase extraction and HPLC determination of 9-benzyladenine and isomeric 9-(nitrobenzyl)adenines and their metabolic N1-oxides present in microsomal incubates

9-Benzyladenine, 9-(2-nitrobenzyl)adenine, 9-(3-nitrobenzyl)adenine and 9-(4-nitrobenzyl)adenine were metabolized to 9-benzyladenine-N1-oxide, 9-(2-nitrobenzyl)adenine-n1-oxide, 9-(3-nitrobenzyl)adenine-N1-oxide and 9-(4-nitrobenzyl)adenine-N1-oxide, respectively, by animal hepatic microsomes. For the quantitative determination of the substrates and metabolites present in microsomal incubates, an off-line solid phase extraction procedure, using columns paced with C18 silica bonded phase, was developed. The extraction recovery for these 9-alkyladenines and their N1-oxides was in the range of 92-101%. A reversed-phase HPLC method was established with an ODS column at a column temperature of 50 degrees C. The mobile phase consisted of H20-MeOH-diethylamine (65:35:0.5, v/v/v). pH 6.8. The above analytes were monitored at 233 nm and retention times of all analytes were within 6-14 min. The within-day coefficients of variation (CV) for the determinations were in an acceptable range. The biotransformation of BA and NBAs to N1-oxides by hamster microsomes was determined under the experimental conditions employed.

Novel anti-inflammatory compounds induce shedding of L-selectin and block primary capture of neutrophils under flow conditions

Leumedins are small molecules that inhibit neutrophil movement into inflamed tissues. These compounds have been shown to inhibit the adherence of neutrophils in static adhesion assays mediated by beta2-integrins. We now report that leumedins, like activating agents, induce the loss of L-selectin from the neutrophil surface. The loss of L-selectin is unrelated to the inhibition of static adhesion, since neutrophils that have been pretreated with leumedins to cause shedding of L-selectin, followed by removal of drug, adhere normally in a static adhesion assay, and this adhesion is inhibited upon readdition of leumedin. In an assay of adhesion to endothelial cells under conditions of physiologic wall shear stress, leumedins prevent both primary capture of neutrophils mediated by L-selectin and firm adherence mediated by beta2-integrins.

Novel anti-inflammatory compounds induce shedding of L-selectin and block primary capture of neutrophils under flow conditions

Leumedins are small molecules that inhibit neutrophil movement into inflamed tissues. These compounds have been shown to inhibit the adherence of neutrophils in static adhesion assays mediated by beta2-integrins. We now report that leumedins, like activating agents, induce the loss of L-selectin from the neutrophil surface. The loss of L-selectin is unrelated to the inhibition of static adhesion, since neutrophils that have been pretreated with leumedins to cause shedding of L-selectin, followed by removal of drug, adhere normally in a static adhesion assay, and this adhesion is inhibited upon readdition of leumedin. In an assay of adhesion to endothelial cells under conditions of physiologic wall shear stress, leumedins prevent both primary capture of neutrophils mediated by L-selectin and firm adherence mediated by beta2-integrins.

High fertilization and pregnancy rates after intracytoplasmic sperm injection in patients with disordered zona pellucida-induced acrosome reaction

OBJECTIVE

To determine whether intracytoplasmic sperm injection (ICSI) is effective treatment for patients with disordered zona pellucida (ZP)-induced acrosome reaction (AR) who have failure of standard IVF-ET.

DESIGN

Tests of sperm-ZP binding and penetration and the ZP-induced AR were used to diagnose patients with disordered ZP-induced AR who then were treated with ICSI.

SETTING

Academic reproductive medicine research laboratory associated with a tertiary referral infertility clinic.

MAIN OUTCOME MEASURE(S)

Clinical features and results of previous IVF-ET, semen analysis and sperm-ZP interaction tests, and ICSI were analyzed.

RESULT(S)

The majority of patients had consistently normal sperm characteristics and all patients had normal sperm-ZP binding but failure of sperm-ZP penetration. The AR of sperm bound to the ZP was significantly lower in the patients (mean 6%, range 0% to 16%) than in the fertile men (mean 61%, range 27% to 96%). Intracytoplasmic sperm injection was performed on 34 patients and the normal fertilization rate averaged 73% per injected oocyte. Five ongoing and eight term pregnancies including two with twins were achieved after an average of two ET procedures per patient were performed. Two couples have second ongoing pregnancies from transfer of frozen embryos after successful first pregnancies. Overall, the implantation rate was 10.5% per embryo and the pregnancy rate 19% per ET and 38% per patient.

CONCLUSION(S)

Disordered ZP-induced AR is a cause of severe infertility and persistent failure of IVF-ET. Intracytoplasmic sperm injection is effective treatment for this condition. Patients with idiopathic infertility should be tested for this condition before commencing IVF-ET treatment.

Selectivity of the human sperm-zona pellucida binding process to sperm head morphometry

OBJECTIVE

To obtain quantitative measures of morphometric selectivity of the human spermzona pellucida binding process as determined by light microscopy.

DESIGN

Fully automated sperm head morphometric based on a 32-dimensional parameterization of images of Shorr-stained sperm. Zona pellucida selected sperm removed from reinseminated oocytes that previously failed IVF.

SETTING

Academic research group associated with a tertiary infertility service.

PATIENT(S)

Semen samples from 51 infertile patients.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Differences in morphometric parameter means observed before and after swim-up and binding to zonae pellucidae.

RESULT(S)

Significant differences between insemination and bound sperm were observed in 17 parameter means and 21 standard deviations. The sperm-zona pellucida binding process preferentially selects sperm heads with a large anterior region with relatively low optical density, as well as high axial symmetry and minimal neck anomalies. Bias against sperm with pyriform morphology was not observed.

CONCLUSION(S)

A causal link has been established between sperm head morphometry, particularly within the acrosomal region, and the ability of sperm to bind to the human zona pellucida. As sperm-zona binding is necessary for fertility, it is possible to derive a physiologically based assessment for clinical diagnosis of male infertility using the "zona-preferred" morphometry results.

Relationship between the zona pellucida (ZP) and ionophore A23187-induced acrosome reaction and the ability of sperm to penetrate the ZP in men with normal sperm-ZP binding

OBJECTIVE

To determine whether the proportions of sperm undergoing the acrosome reaction (AR) on the zona pellucida (ZP) or on exposure to the calcium ionophore A23187 correlate with sperm-ZP penetration in men with normal sperm-ZP binding.

DESIGN

Sperm samples from 14 fertile, 50 normozoospermic, and 21 teratozoospermic men with normal sperm-ZP binding were used to study ZP and ionophore-induced AR and sperm-ZP penetration.

SETTING

University research unit associated with a clinical infertility and IVF program.

MAIN OUTCOME MEASURES

The proportion of sperm undergoing the AR induced by ZP and A23187, the number of sperm bound to and penetrating into the ZP, the proportion of ZP penetrated by sperm, and semen characteristics were analyzed.

RESULTS

There were highly significant correlations between the percentage AR of sperm bound to the ZP and both the proportion of ZP penetrated and average number of sperm penetrating per ZP (Spearman r = 0.697 and 0.703). In contrast, A23187-induced AR did not correlate with either ZP-induced AR or sperm-ZP penetration. Although sperm concentration in semen correlated with both ZP-induced AR and sperm-ZP penetration by Spearman test, it was not significant in multivariate regression analyses.

CONCLUSION

Ionophore A23187-induced AR does not correlate with either ZP-induced AR or sperm-ZP penetration. The ZP-induced AR is correlated highly with sperm-ZP penetration. Testing ZP-induced AR may be useful for assessing infertile men with normal sperm-ZP binding. In particular, it will identify failure of ZP penetration because of specific defects of the AR on the ZP.

A simple method for assessment of the human acrosome reaction of spermatozoa bound to the zona pellucida: lack of relationship with ionophore A23187-induced acrosome reaction

Acrosome reactions induced by the calcium ionophore A23187 and zona pellucida (ZP) were studied. Sperm samples were obtained from fertile men or men with normal semen analysis and normal sperm-ZP binding. Oocytes were obtained, with the consent of the patients, after the failure of fertilization in vitro. Motile spermatozoa selected by a swim-up technique were incubated with 10 microM A23187 for 1 h, four oocytes for 2 h or solubilized ZP (4 ZP/microliters) for 2 h. Spermatozoa bound to the ZP were dislodged and collected in a small volume of phosphate-buffered saline by aspirating the oocytes with a glass pipette with an inner diameter (120 microns) slightly smaller than the diameter of the oocyte. The acrosome status of the spermatozoa was determined using fluorescein-labelled Pisum sativum agglutinin. The proportion of spermatozoa undergoing the acrosome reaction on the ZP at 2 h varied over a wide range (5-99%), but the agreement between results for the same semen sample exposed to different groups of oocytes was good: the standard deviations of the differences being 9%. Pre-incubation of spermatozoa for 2 h did not increase the ZP-induced acrosome reaction. Re-incubation of ZP with the same sperm suspension for 2 h after removing ZP-bound spermatozoa from the first 2 h incubation produced a significantly lower ZP-induced acrosome reaction in the second incubation (22 +/- 16%) than in the first incubation (30 +/- 14%; P < 0.001, n = 20). There was no significant difference in the ZP-induced acrosome reaction with oocytes with ZP which had or had not been penetrated by spermatozoa during the in-vitro fertilization insemination. Pre-incubation of spermatozoa with solubilized ZP blocked sperm-ZP binding. However, the acrosome reaction induced by solubilized ZP (4 ZP/microliters) was significantly lower than the acrosome reaction induced by intact ZP (10 +/- 5 and 30 +/- 13% respectively, n = 11, P < 0.001), but there was a high correlation (Spearman r = 0.822, P < 0.01) between the results. On the other hand, although the average of the acrosome reaction was similar for A23187 (42%) and for ZP (43%), there was no significant correlation between the results for the two stimuli (n = 60). In conclusion, a useful method for assessing the ZP-induced acrosome reaction has been developed using oocytes which failed to fertilize in vitro. The lack of a relationship between the result of the chemical (A23187) and physiological (ZP) stimuli for the acrosome reaction in the same subjects questions the biological basis of using A23187 for tests of sperm function. Solubilized human ZP in a concentration that blocks sperm-ZP binding is a less efficient inducer of the acrosome reaction than is intact ZP. It is possible that the three-dimensional structure of the ZP is important for induction of the acrosome reaction or that spermatozoa which bind to the ZP are more likely to acrosome react. Assessment of the physiological acrosome reaction for diagnosis of sperm defects which interfere with the fertilization process should be concentrated on the spermatozoa which are capable of binding to the ZP.

Novel anti-inflammatory compounds prevent CD11b/CD18, alpha M beta 2 (Mac-1)-dependent neutrophil adhesion without blocking activation-induced changes in Mac-1

Leumedins are small organic molecules with anti-inflammatory properties in vivo. We report here that leumedins inhibit the CD11b/CD18 alpha M beta 2 (Mac-1)-dependent adherence of neutrophils to serum proteins. The activation of neutrophils leading to adherence via Mac-1 is associated with an increase in cell surface Mac-1 level, and with an increased affinity of Mac-1 for adhesion partners. Inhibition of neutrophil adherence by leumedins does not require blocking the recruitment of Mac-1 from intracellular granules to the cell surface. Furthermore, leumedins do not block the expression on Mac-1 of the epitope for an "activation-specific" antibody (CBRM1/5). Time course studies show that leumedins inhibit adherence by targeting an event which occurs concurrently with changes in Mac-1 level and induction of the CBRM1/5 epitope. Therefore, leumedins block an unknown process which is permissive for Mac-1-dependent adherence.