Influence of the extent of hydrophobicity on water organization and dynamics on 2D graphene oxide surfaces

Graphene oxide (GO) nanomaterials are being extensively explored for a wide spectrum of applications, ranging from water desalination to fuel cell applications due to their tunable mechanical, thermal, and electrical...

The effect of DTPA on calcium carbonate scale deposition on copper and aluminium surfaces

Calcium carbonate (CaCO₃) scale inhibition by Diethylenetriaminepentaacetic acid (DTPA) on copper and aluminium metal surfaces was studied at 60 and 100 °C. The samples were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results revealed a novel pot like morphology for calcite which was resulted from the transformation of dumbbell morphology. The pot like morphology exposed the possibility of hollow structures for other polymorphs and is resulted from the breaking apart of the dumbbell structures at the middle, followed by fluffing of the separated parts.

Solution structure and tandem DNA recognition of the C-terminal effector domain of PmrA from Klebsiella pneumoniae

Klebsiella pneumoniae PmrA is a polymyxin-resistance-associated response regulator. The C-terminal effector/DNA-binding domain of PmrA (PmrAC) recognizes tandem imperfect repeat sequences on the promoters of genes to induce antimicrobial peptide resistance after phosphorylation and dimerization of its N-terminal receiver domain (PmrAN). However, structural information concerning how phosphorylation of the response regulator enhances DNA recognition remains elusive. To gain insights, we determined the nuclear magnetic resonance solution structure of PmrAC and characterized the interactions between PmrAC or BeF3(-)-activated full-length PmrA (PmrAF) and two DNA sequences from the pbgP promoter of K. pneumoniae. We showed that PmrAC binds to the PmrA box, which was verified to contain two half-sites, 5'-CTTAAT-3' and 5'-CCTAAG-3', in a head-to-tail fashion with much stronger affinity to the first than the second site without cooperativity. The structural basis for the PmrAC-DNA complex was investigated using HADDOCK docking and confirmed by paramagnetic relaxation enhancement. Unlike PmrAC, PmrAF recognizes the two sites simultaneously and specifically. In the PmrAF-DNA complex, PmrAN may maintain an activated homodimeric conformation analogous to that in the free form and the interactions between two PmrAC molecules aid in bending and binding of the DNA duplex for transcription activation.

Structural effect of the L16Q, K50E, and R53P mutations on homeodomain of pituitary homeobox protein 2

The transcription factor pituitary homeobox protein 2 (PITX2) is involved in genetic control of development. Mutations in PITX2, most in the homeodomain, cause the autosomal-dominant disorder Rieger syndrome. The mutants L16Q, K50E and R53P destabilize the structure and disrupt DNA-binding activity. The biological functions of these mutants have been characterized but not the structural basis behind the loss of DNA-binding activity. We performed multiple molecular dynamics simulations at 37°C to investigate the structural and dynamic effects of the 3 PITX2 homeodomain mutants. Compared with the wild type (WT), the L16Q mutant induces a kink in the α3 helix, which is stabilized by the hydrogen bond of Q21-R59. The disruption in backbone hydrogen bonds of V47-N51 and W48-R52 leads to a kink formation in the α3 helix of K50E. The R53P mutant alters the relative orientation of helices, which is apparently stabilized by the formation of new hydrogen bonds of T38-Q11, T38-Q12, T38-R2, N39-R2, L40-Q1, L40-R2, and T41-Q4. The hydrophobic core residues F8, L13, L40 and V45 change their positions in all mutants to break the hydrophobic core. Thus, changes in helical orientations and hydrophobic core cause rearrangement of the DNA-binding surface and disrupt DNA-binding activity in the mutants. The structural and molecular dynamics properties of 3 PITX2 homeodomain mutants differ from those of the WT, especially in formation of a kink in the recognition helix, change in the packing of helices and disruption of the hydrophobic core. This structural basis for the loss of DNA-binding activity for these polymorphisms may help in understanding the effect of mutations on other homeodomains with other diseases.

Effects of single nucleotide polymorphisms on human N-acetyltransferase 2 structure and dynamics by molecular dynamics simulation

Background

Arylamine N-acetyltransferase 2 (NAT2) is an important catalytic enzyme that metabolizes the carcinogenic arylamines, hydrazine drugs and chemicals. This enzyme is highly polymorphic in different human populations. Several polymorphisms of NAT2, including the single amino acid substitutions R64Q, I114T, D122N, L137F, Q145P, R197Q, and G286E, are classified as slow acetylators, whereas the wild-type NAT2 is classified as a fast acetylator. The slow acetylators are often associated with drug toxicity and efficacy as well as cancer susceptibility. The biological functions of these 7 mutations have previously been characterized, but the structural basis behind the reduced catalytic activity and reduced protein level is not clear.

Methodology/Principal Findings

We performed multiple molecular dynamics simulations of these mutants as well as NAT2 to investigate the structural and dynamical effects throughout the protein structure, specifically the catalytic triad, cofactor binding site, and the substrate binding pocket. None of these mutations induced unfolding; instead, their effects were confined to the inter-domain, domain 3 and 17-residue insert region, where the flexibility was significantly reduced relative to the wild-type. Structural effects of these mutations propagate through space and cause a change in catalytic triad conformation, cofactor binding site, substrate binding pocket size/shape and electrostatic potential.

Conclusions/Significance

Our results showed that the dynamical properties of all the mutant structures, especially in inter-domain, domain 3 and 17-residue insert region were affected in the same manner. Similarly, the electrostatic potential of all the mutants were altered and also the functionally important regions such as catalytic triad, cofactor binding site, and substrate binding pocket adopted different orientation and/or conformation relative to the wild-type that may affect the functions of the mutants. Overall, our study may provide the structural basis for reduced catalytic activity and protein level, as was experimentally observed for these polymorphisms.

Structure of the Trichomonas vaginalis Myb3 DNA-binding domain bound to a promoter sequence reveals a unique C-terminal β-hairpin conformation

Trichomonas vaginalis Myb3 transcription factor (tvMyb3) recognizes the MRE-1 promoter sequence and regulates ap65-1 gene, which encodes a hydrogenosomal malic enzyme that may play a role in the cytoadherence of the parasite. Here, we identified tvMyb3_53–180 as the essential fragment for DNA recognition and report the crystal structure of tvMyb3_53–180 bound to MRE-1 DNA. The N-terminal fragment adopts the classical conformation of an Myb DNA-binding domain, with the third helices of R2 and R3 motifs intercalating in the major groove of DNA. The C-terminal extension forms a β-hairpin followed by a flexible tail, which is stabilized by several interactions with the R3 motif and is not observed in other Myb proteins. Interestingly, this unique C-terminal fragment does not stably connect with DNA in the complex structure but is involved in DNA binding, as demonstrated by NMR chemical shift perturbation, ¹H-¹⁵N heteronuclear-nuclear Overhauser effect and intermolecular paramagnetic relaxation enhancement. Site-directed mutagenesis also revealed that this C-terminal fragment is crucial for DNA binding, especially the residue Arg¹⁵³ and the fragment K¹⁷⁰KRK¹⁷³. We provide a structural basis for MRE-1 DNA recognition and suggest a possible post-translational regulation of tvMyb3 protein.

Investigation of cation-π interactions in sugar-binding proteins

Cation-π interaction is a non-covalent binding force that plays a significant role in protein stability and drug-receptor interactions. In this work, we have investigated the structural role of cation-π interactions in sugar-binding proteins (SBPs). We observed 212 cation-π interactions in 53 proteins out of 59 SBPs in dataset. There is an average one energetically significant cation-π interaction for every 66 residues in SBPs. In addition, Arg is highly preferred to form cation-π interactions, and the average energy of Arg-Trp is high among six pairs. Long-range interactions are predominant in the analyzed cation-π interactions. Comparatively, all interaction pairs favor to accommodate in strand conformations. The analysis of solvent accessible area indicates that most of the aromatic residues are found on buried or partially buried whereas cationic residues were found mostly on the exposed regions of protein. The cation-π interactions forming residues were found that around 43% of cation-π residues had highly conserved with the conservation score ≥6. Almost cationic and π-residues equally share in the stabilization center. Sugar-binding site analysis in available complexes showed that the frequency of Trp and Arg is high, suggesting the potential role of these two residues in the interactions between proteins and sugar molecules. Our observations in this study could help to further understand the structural stability of SBPs.

NMR structural analysis of DNA recognition by a novel Myb1 DNA-binding domain in the protozoan parasite Trichomonas vaginalis

The transcription regulator, tvMyb1, is the first Myb family protein identified in Trichomonas vaginalis. Using an electrophoretic mobility shift assay, we defined the amino-acid sequence from Lys(35) to Ser(141) (tvMyb1(35-141)) as the minimal DNA-binding domain, encompassing two Myb-like DNA-binding motifs (designated as R2 and R3 motifs) and an extension of 10 residues at the C-terminus. NMR solution structures of tvMyb1(35-141) show that both the R2 and R3 motifs adopt helix-turn-helix conformations while helix 6 in the R3 motif is longer than its counterpart in vertebrate Myb proteins. The extension of helix 6 was then shown to play an important role in protein stability as well as in DNA-binding activity. The structural basis for the tvMyb1(35-141)/DNA interaction was investigated using chemical shift perturbations, residual dipolar couplings, DNA specificity data and data-driven macromolecular docking by HADDOCK. Our data indicate that the orientation between R2 and R3 motifs dramatically changes upon binding to DNA so as to recognize the DNA major groove through a number of key contacts involving residues in helices 3 and 6. The tvMyb1(35-141)/DNA complex model furthers our understanding of DNA recognition by Myb proteins and this approach could be applied in determining the complex structures involving proteins with multiple domains.

Systematic review of hypnotherapy for treating symptoms in terminally ill adult cancer patients

The aim of this review was to find the evidence for or against the use of hypnotherapy in the treatment of symptoms in terminally ill adult cancer patients. The title and abstract were evaluated following a search through Index Medicus/MEDLINE, EMBASE, CINHAHL, CancerLit, AHMED, Psychinfo, CISCOM, Cochrane and DARE. Search terms included hypnotherapy, cancer, terminal care and palliative care. Inclusion criteria included systematic reviews, randomized controlled trials, observational and prospective studies, retrospective surveys, case studies and reports. A total of 27 papers were evaluated. Two reviewers assessed the studies, one extracted the relevant data and 10% were evaluated independently by a third reviewer. The 27 papers comprised a randomized controlled trial, an observational study, a retrospective questionnaire and 24 case studies. Hypnotherapy was used to treat a variety of symptoms, including pain, anxiety and depression. The poor quality of the studies and heterogeneity of the study population limited further evaluation; further research is required to understand the role of hypnotherapy in managing symptoms.

Phosphodiesterase-5 inhibition synergizes rho-kinase antagonism and enhances erectile response in male hypertensive rats

To evaluate the association between hypertension, male erectile function, Rho-kinase, and cyclic GMP pathways, we monitored neurogenic erectile response in spontaneously hypertensive (SHR) vs normotensive rats. We also evaluated SHR erectile function before and after intracavernosal injection of either the specific Rho-kinase inhibitor Y-27632 or a combination of Y-27632 and the PDE5 inhibitor zaprinast to prevent cGMP degradation. SHR had lower resting baseline corpus cavernosum pressure and a higher threshold for development of tumescence than normotensive rats. In SHR, Y-27632 administration reversed hypertension-related changes in male erectile function; Rho-kinase antagonism and PDE5 inhibition in combination had a synergistic effect in improving the neurogenic erectile response. Our data indicate that hypertension is associated with impairment in the SHR neurogenic erectile response that may involve a derangement in hemodynamic mechanisms in penile erectile tissue. Rho-kinase inhibition alone or combined with PDE5 inhibition may be of value in treating hypertension-related ED.

Injection practices in southern part of India

The World Health Organization defines 'a safe injection' as one that does not harm the recipient, does not expose the provider to any avoidable risk, and does not result in any waste that is dangerous to the community. Irrational and unsafe injection practices are rife in developing countries. The objective of the present study was to assess the injection practices in the state of Tamilnadu, India, using the Rapid assessment and response guide of the Safe Injection Global Network of the World Health Organization. Thirty-nine prescribers, 62 providers, and 175 members of the general public were interviewed. The areas were chosen out of convenience while at the same time adhering to the guidelines. The study was carried out between April and June 2001. The per capita injection rate was 2.4 per year. The ratio of therapeutic to immunization injections was 6.5:1, and the proportion of injections given with a disposable syringe and needle was 35.4%. Knowledge about diseases transmitted by unsafe injections, for example involving human immunodeficiency virus and hepatitis B virus, was greater among all the study groups. The annual incidence of needlestick injuries among providers was 23.6, which is extremely high. It is concluded that there are deficiencies in practice such as an excessive, unwarranted usage of injections, a sizeable prevalence of unsafe injection practices, the short supply of injection equipment leading to a high incidence of needlestick injuries, a low proportion of hepatitis B virus immunization among providers, and a lack of adequate sharps containers and disposal facilities in this part of India. It is suggested that immediate and long-term remedial measures, such as the education of prescribers to reduce the number of injections to a bare minimum, an adequate supply of injection equipment, provider protection with immunization for hepatitis B virus, the provision of adequate sharps containers with safe disposal facilities and, not least, community education, be undertaken to avoid the future epidemic of transmissible diseases.

Erectile dysfunction: current concepts and future directions

Major advances in science and medicine have led to improved understanding of the pathophysiology of erectile dysfunction. The development of reliable pharmacological therapy for erectile dysfunction has led to heightened awareness in the public and medical communities. This article reviews recent clinical advances and future research directions.

A comparative study of the knowledge, beliefs, and practices of diabetic patients cared for at a teaching hospital (free service) and those cared for by private practitioners (paid service)

The aim of this study was to determine and compare the knowledge, beliefs, and practices of diabetics receiving free medical care and those paying for medical care in Tamilnadu, India. A questionnaire was administered to elicit diabetic patients' knowledge regarding diet, exercise, adverse effects, habits, and other matters; their beliefs about diabetes; and their practices regarding diet, medication, and self-monitoring. The results showed a large gap between knowledge and action in both groups and a need for increased efforts toward patient education regarding diabetes.

Characterization of ultrastructural and metabolic abnormalities in semen from men with spinal cord injury

BACKGROUND

In men with spinal cord injury (SCI), fertility is impaired because of a combination of ejaculatory dysfunction and poor semen quality. We hypothesized that ultrastructural and metabolic abnormalities of sperm could be an underlying factor in infertility in these men.

METHODS

To investigate mechanisms contributing to the abnormal sperm parameters, we analyzed seminal constituents and sperm ultrastructure in ejaculates from 7 men with SCI and compared them with 5 control subjects. Sperm adenosine triphosphate (ATP) content was measured using a firefly luciferase bioluminescent assay kit, and ultrastructure was evaluated by electron microscopy. Seminal oxidative stress (8-iso-prostaglandin F-2alpha [8-iso-PGF2alpha]) and transforming growth factor-beta1 (TGF-beta1) levels were measured by specific enzyme-linked immunoabsorbent assay kits.

RESULTS

Semen samples from men with SCI showed azoospermia (3) and severe asthenospermia (2; motility 0-5%). A majority (65%) of sperm from asthenospermic samples showed degenerative changes and significant axonemal defects. Incubation of normal sperm with SCI seminal plasma induced a concentration-dependent decrease in sperm motility (43%) accompanied by a significant drop in intracellular ATP content (33%). Semen samples from men with SCI exhibited levels of 8-iso-PGF2alpha 3.5-fold higher than those from controls and levels of TGF-beta1 that were 10% higher than those from controls.

CONCLUSION

Our results suggest that seminal constituents of men with SCI are detrimental to sperm movement and that ultrastructural degenerative changes may contribute to the impaired sperm motility and viability seen in these patients. These preliminary results must be confirmed in larger patient populations and longitudinal studies.

Role of genitourinary inflammation in infertility: synergistic effect of lipopolysaccharide and interferon-gamma on human spermatozoa

Pro-inflammatory cytokines are elevated in the semen of patients with genitourinary inflammation (GUI). Whether this increase in cytokines in GUI patients plays any critical role in male factor infertility is not clear. The present study investigated the in vitro effects of two important pro-inflammatory cytokines, lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), on sperm motility, viability, membrane integrity and motion parameters. Washed spermatozoa from healthy donors were incubated with LPS (0.1 mg/mL) or IFN-gamma (0.1 mg/mL) alone or in combination. Sperm motility, viability, membrane integrity and computer-assisted motion were evaluated at various time intervals (0, 30, 60 and 180 min) after treatment. Sperm membrane integrity was analysed using the hypo-osmotic swelling test (HOST). LPS and IFN-gamma individually did not alter sperm viability or motility, but their combination showed a significant time-dependent decrease (p < 0.05) in sperm motility, viability and membrane integrity. Sperm motion parameters (straight-line velocity, curvilinear velocity, mean linearity, or amplitude of lateral head displacement) were not affected by LPS or IFN-gamma at the concentrations used in this study. These data suggest that the combination of LPS and IFN-gamma is detrimental to human spermatozoa and may contribute to male factor infertility in patients with chronic GUI.

Nitric oxide induces oxidative stress and mediates cytotoxicity to human cavernosal cells in culture

Nitric oxide (NO) is a product of nitric oxide synthase (NOS) activity and is recognized as the main mediator of penile erection by induction of cavernosal smooth muscle relaxation. Although excessive NO can be generated via inducible NOS activation under certain inflammatory and noninflammatory conditions, for example, in response to TGF-beta and gamma-IFN (the proinflammatory cytokines), the effect of excessive NO produced as reactive nitrogen radical (NO.-) in the corpora cavernosa is not known. The present study was designed to evaluate whether the effect of NO.- on human cavernosal cells in primary culture is via oxidative stress. Cell growth was monitored by DNA synthesis, and mitochondrial function was evaluated by adenosine triphosphate (ATP) production. Primary culture was initiated with explants from human corpora cavernosa, and the monolayer cavernosal cells (passage 2-3) were plated on 12-well tissue culture plates. At 70%-80% confluency, the cells were incubated with varying concentrations of sodium nitroprusside (SNP) for 16 hours. The cell growth (DNA synthesis) was monitored by measuring [3H] thymidine incorporation, ATP levels (nanomoles per 10(4) cells) were measured by chemiluminescence assay using a luminometer, the total oxidative stress was monitored by measuring the levels of 8-iso PGF2alpha (picograms per milliliter) by using an enzyme-linked immunosorbent assay kit, and NO production was monitored by accumulation of nitrite levels (micrometer per 10(4) cells). Human cavernosal smooth muscle cells (HCSMC) exposed to SNP (0 to 0.8 mM) exhibited a dose-dependent (two- to fivefold) decrease in DNA and ATP synthesis, accompanied by a two- to threefold increase in the levels of 8-iso PGF2alpha and about an eightfold increase in nitrite accumulation. These findings suggest that the NO released by SNP (>0.8 mM) exhibited a significant cytotoxicity to HCSMC, mediated by increased oxidative stress to these cells.

Potentiation of erectile response and cAMP accumulation by combination of prostaglandin E1 and rolipram, a selective inhibitor of the type 4 phosphodiesterase (PDE 4)

PURPOSE

Phosphodiesterases (PDEs) are an important component of the signal transduction pathway during the erectile response. To determine the PDE isoforms in the corpora cavernosa in the cat and to establish the functional presence of PDE 4 in human cavernosal tissue, the erectile response to intracavernosal phosphodiesterase (PDE) inhibitors alone and the combination of PDE inhibitors and prostaglandin E1 (PGE1) was evaluated in the anesthetized cat. The in vitro formation of cAMP and cGMP in human cavernosal smooth muscle cells (HCSMCs) treated with PGE1 and rolipram in primary culture was also measured.

MATERIALS AND METHODS

In pentobarbital-anesthetized cats, increases in intracavernosal pressure, penile length, and duration of erectile response were determined after intracavernosal injections of (i) the type 3 cAMP-specific, cGMP-inhibitable PDE inhibitor, milrinone, (ii) the type 4 cAMP-specific PDE inhibitor, rolipram, (iii) the type 5 cGMP-specific PDE inhibitor, zaprinast, and (iv) the combination of rolipram and PGE1. Systemic arterial pressure was concurrently assessed in these experiments. All responses to PDE inhibitors were compared with a control triple-drug combination comprised of papaverine (1.65 mg.), PGE1 (0.5 microg.), and phentolamine (25 microg.). HCSMCs were incubated with PGE1 (3 microM) and rolipram (10 microM) individually or in combination up to 2 hours at 37C. The intracellular cAMP and cGMP was extracted by cold absolute ethanol and measured (pmol./10(6) cells) by a commercially available EIA kit.

RESULTS

Milrinone (3 to 100 microg.), rolipram (3 to 100 microg.), and zaprinast (3 to 100 microg.) induced dose-dependent increases in intracavernosal pressure and penile length (p <0.05) when administered intracavernosally. The maximum increase in cavernosal pressure in response to zaprinast was associated with no significant change in systemic arterial pressure. When rolipram was combined with PGE1 (0.1 microg.), the increases in intracavernosal pressure and the duration of erectile response were significantly higher (p <0.05) and longer (p <0.05) than those observed when rolipram alone was injected intracavernosally. PGE1 (3 microM) and rolipram (10 microM) produced significant increases (p <0.05) in the accumulation of intracellular cAMP levels in HCSMCs in primary culture above those of the baseline values while intracellular levels of cGMP did not change.

CONCLUSIONS

PDE inhibitors administered intracavernosally caused dose-dependent increases in cavernosal pressure in the cat. When a specific cAMP PDE inhibitor was combined with PGE1, the erectile response was enhanced and intracellular levels of cAMP were increased in HCSMCs in primary culture. These data suggest further exploration of the combination of various PDE inhibitors and PGE1 in the pharmacologic treatment of erectile dysfunction and provide functional evidence for the presence of PDE 4 isoenzyme in human penile cavernosal cells.

Male infertility and erectile dysfunction in spinal cord injury: a review

OBJECTIVE

To review the pathophysiology, evaluation, and management of erectile dysfunction and infertility in spinal cord injury (SCI).

STUDY SELECTIONS

Studies that covered various treatment options and their contraindications, complications, or side effects, including sildenafil (Viagra), intracavernosal injection therapy, topical medications and a urethral delivery system, a vacuum erection device, and penile prostheses. Other studies covered the effects of SCI on reproduction: spermatogenesis and testicular function, and seminal constituents. In addition, assisted reproductive techniques were compared: external vibratory stimulation, electroejaculation, testicular sperm aspiration, and intracytoplasmic sperm injection.

CONCLUSION

Goal-directed therapy is the mainstay of treatment of erectile dysfunction in men with or without SCI. The choice of therapy is often defined more by the needs of the patient's sexual relationship than by his erectile dysfunction. The majority of men with SCI are infertile because of a combination of ejaculatory dysfunction, impaired spermatogenesis, and poor semen quality. Although many technological advances have evolved to overcome ejaculatory dysfunction, the sperm density, motility, and function remain poor. Until these parameters are improved, men with SCI will have to pursue more financially and emotionally taxing procedures. Further studies to elucidate the cellular and molecular mechanisms of diminished sperm quality are needed. Addressing the issues of erectile dysfunction and male infertility may help to preserve the relationship between the patient and his partner.

Characterization of reactive oxygen species induced effects on human spermatozoa movement and energy metabolism

Reactive oxygen species (ROS) inhibit sperm movement and have been implicated in male infertility. In this study, we determined the effects of specific ROS produced by activated leukocytes on human spermatozoa and investigated their metabolic site of action. We used chemiluminescence and electron paramagnetic resonance (EPR) to characterize the ROS generated by both blood and seminal leukocytes. We also determined the effects of these ROS on sperm energy metabolism using biochemical analyses and flow cytometry. Both blood and seminal leukocytes produced the same characteristic ROS which were determined to be hydrogen peroxide (H2O2) and superoxide radicals (O2*-). EPR using the spin trapping technique indicated that superoxide radical-dependent hydroxyl radicals (HO.) were also generated. ROS generated by PMA-stimulated blood leukocytes (2-5 x 10(6)/ml) caused inhibition of sperm movement in 2 h (p < .01). Using the hypoxanthine/ xanthine oxidase (0.5 U/ml) system to generate ROS, we determined that spermatozoa ATP levels, after ROS treatment, were reduced approximately eight-fold in 30 min (0.10 x 10(10) moles/10(6) sperm cells) compared to control (0.84 X 10(-10) moles/10(6) sperm cells) (p < .01). Sperm ATP reduction paralleled the inhibition of sperm forward progression. Neither superoxide dismutase (100 U/ml) nor dimethyl sulfoxide (100 mM) reversed these effects; however, protection was observed with catalase (4 X 10(3) U/ml). Flow cytometric analyses of sperm treated with various doses of H2O2 (0.3 mM-20.0 mM) showed a dose-dependent decrease in sperm mitochondrial membrane potential (MMP); however, at low concentrations of H2O2, sperm MMP was not significantly inhibited. Also, sperm MMP uncoupling with CCClP had no effect on either sperm ATP levels or forward progression. These results indicate that H2O2 is the toxic ROS produced by activated leukocytes causing the inhibition of both sperm movement and ATP production. O2*- and HO. do not play a significant role in these processes. Low concentrations of H2O2 causing complete inhibition of sperm movement and ATP levels inhibit sperm energy metabolism at a site independent of mitochondrial oxidative phosphorylation.

Ex vivo expression of nitric oxide synthase isoforms (eNOS/iNOS) and calmodulin in human penile cavernosal cells

PURPOSE

Nitric oxide (NO) synthesized by nitric oxide synthase (NOS) is recognized as the central mediator of penile erection. This process appears to be mediated mainly by neuronal NOS (nNOS), which is localized to the nonadrenergic, noncholinergic innervation of the penis. However, the role of non-neuronal penile constituents (specifically the cavernosal smooth muscle), as well as other NOS isoforms in NO production in the human penis is not well understood. The present study evaluates the expression of non-neuronal (inducible and endothelial) isoforms of NOS in human penile cavernosal smooth muscle cells in culture.

MATERIALS AND METHODS

Primary culture was initiated with explants of human corpora cavernosa. For gene expression studies, total RNA was extracted from cavernosal cells and subjected to reverse transcriptase polymerase chain reaction (RT-PCR). For NADPH-diaphorase histochemistry, the cells were incubated with 1 mM beta-NADPH and 0.5 mM nitrobluetetrazolium at 37C for 3 hours. For indirect immunofluorescence and electron microscopy, cells were incubated overnight at 4C with specific primary (eNOS; calmodulin) and secondary antibodies. A conventional avidin biotin complex technique was used for electron microscopy.

RESULTS

The mRNA expression studies revealed that these cells express both endothelial (eNOS) and inducible (iNOS) forms. Localization studies showed positive signals for NADPH-diaphorase, eNOS, and calmodulin. The electron microscopic evaluation confirmed the localization of eNOS to the cytoplasm and small vesicles in the cells.

CONCLUSIONS

These findings support the hypothesis that human cavernosal smooth muscle cells express both endothelial and inducible forms of NOS, which may significantly contribute to NO production in the penile architecture during the erectile process.

The influence of castration on pharmacologically induced penile erection in the cat

The purpose of this study was to investigate the in vivo effects of intracavernosal injections of adrenomedullin (ADM), calcitonin gene-related peptide (CGRP), nociceptin, vasoactive intestinal polypeptide (VIP), sodium nitroprusside (SNP), and prostaglandin E1 (PGE1) on penile erection in castrated and intact (control) anesthetized cats. Erectile responses to ADM, CGRP, nociceptin, VIP, SNP, and PGE1 were compared with responses to a standard triple-drug combination (1.65 mg of papaverine, 25 microg of phentolamine, and 0.5 microg of PGE1) in both castrated and control cats. In control animals, ADM, CGRP, nociceptin, VIP, SNP, and PGE1 induced penile erections similar to those elicited by the triple-drug combination. However, in castrated animals, there was a significant decrease in erectile response; the response to intracavernosal injection of the standard triple-drug combination in castrated cats was 28% of that of the control group of animals. Serum testosterone levels demonstrated a significant (P < 0.0001) positive correlation (r = 0.52) with intracavernosal pressure in response to the standard combination. A marked reduction in serum testosterone levels was observed in castrated cats when measured by radioimmunoassay (0.34 +/- 0.1 ng/dl in castrated cats, compared with 31.15 +/- 6 ng/dl in control cats). These data suggest that the presence of testosterone is a necessary prerequisite to sustain a pharmacologically induced penile erection in the cat.

Antioxidant potential of human serum albumin: role in the recovery of high quality human spermatozoa for assisted reproductive technology

Human serum albumin (HSA) is being considered as an alternate media for sperm enrichment in assisted reproductive technology (ART) because of recent concern with the use of Percoll. In this study, we compared HSA and Percoll for 1) sperm recovery, 2) reactive oxygen species scavenging potential, and 3) effects on total oxidative stress to spermatozoa. The spermatozoa-enriched fractions obtained from Percoll (80%:40%) and HSA (12%) were monitored for sperm motility, viability, hypoosmotic swelling test (HOST), and adenosine triphosphate (ATP) levels. The effect of superoxide anions (O2.-) on donor human spermatozoa was observed in the presence of either HSA or Percoll media. A combination of luminol and the Cypridina luciferin analog 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo(1,2-alpha)pyraz in-3-one hydrochloride was used as a highly sensitive chemiluminescence probe in our hypoxanthine and xanthine oxidase-based assay for O2.-. Sperm membrane total oxidative stress was determined by measuring levels of the prostanoid 8-iso-Prostaglandin F2alpha (8-iso-PGF2alpha). Significant differences in sperm parameters between the Percoll-enriched spermatozoa (motility 60%+/-4%, viability 56%+/-6%, and HOST 73%+/-7%) and those enriched with HSA (motility 84%+/-5%, viability 85%+/-4%, and HOST 84%+/-3%; P < 0.01) were observed. Adenosine triphosphate levels were significantly higher, by almost 50%, in samples processed with HSA than with Percoll (P=0.03). The dismutation rate of O2.- in HSA (slope -6.8) was significantly lower than in Percoll (slope -87.0; P < 0.01). Sperm motility and ATP levels decreased at a slower rate after treatment with O2.- in the presence of HSA when compared to Percoll; moreover, spermatozoa in HSA regained partial motility after 2 hours, whereas spermatozoa in Percoll were immobilized. No significant differences in 8-iso-PGF2alpha levels in spermatozoa enriched by either HSA or Percoll were observed. We conclude that the HSA sperm enrichment procedure improves the recovery of higher quality spermatozoa compared to Percoll and, because of its antioxidant properties, may be useful in processing high leukospermia semen samples for ART purposes.

Effect of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on human sperm motility, viability and motion parameters

Male genital tract infections and non-specific inflammatory conditions may be associated with unexplained infertility. Previous studies have shown the presence of cytokines such as tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in the semen of infertile men. However, the mechanism of effect of these cytokines on human sperm function is still controversial. The present study was undertaken to investigate the in-vitro effects of TNF-alpha and IFN-gamma on human sperm motion, viability and the hypoosmotic swelling test (HOST). Washed spermatozoa from normal volunteers (n = 9) were incubated in the presence/absence of TNF-alpha (1 microgram/mL) plus IFN-gamma (0.1 microgram/mL). Sperm motility, viability, HOST, and video sequences were recorded at different time intervals (0, 30, 60 and 180 min). Sperm motion parameters were analysed using computer-assisted semen analysis. There was a time-dependent negative effect of TNF-alpha plus IFN-gamma on sperm motility, viability, HOST, and lateral-head displacement (ALH). The maximum decrease was observed between 60 and 180 min for sperm motility (50.8 +/- 5.6%), viability (52.8 +/- 4.0%), HOST (38 +/- 2%) and ALH (4.7 +/- 0.1 microns) compared to control samples (62.2 +/- 2.8, 62.4 +/- 2.9, 58 +/- 4, and 5.3 +/- 0.4, respectively; All p < 0.05). There was no significant effect on sperm straight-line velocity and mean linearity when compared to control. These data suggest that the common inflammatory cytokines TNF-alpha plus IFN-gamma have only partial detrimental effects on sperm motility, viability, membrane integrity and lateral head displacement, which may contribute to the poor fertilizing potential of human spermatozoa during inflammatory conditions.

Effects of luminal nutrients and small bowel transplants on congenital indirect hyperbilirubinemia

The Gunn rat is an excellent model of Crigler-Najjar syndrome, type 1. In previous studies we demonstrated that heterotopic 15-20-cm jejunal transplants from Wistar rats lowered serum bilirubin levels by 40%, and the reduction was transient (6 weeks). In contrast, orthotopic transplants decreased bilirubin levels by 60% and the effect persisted throughout the 8-week study. This study was initiated to identify the luminal substance(s) which are responsible for the persistent bilirubin-lowering effect of jejunal transplants. Thirty-one Wistar to Gunn 15-20-cm jejunal transplants were randomized to receive daily Thiry-Vella graft irrigation with 5 ml of normal saline (n = 8); bile salts (cholate + deoxycholate, 40 mg/ml, n = 5; fats (Microlipid, 20 mg/ml, n = 5); proteins (Casec caseinate, 40 mg/ml, n = 5); and sugars (Moducal + Polycose, 40 mg/ml, n = 8). Bilirubin levels were measured spectrophotometrically at weekly intervals. At 4 and 8 weeks, enzyme-induced bilirubin conjugation activity was measured using added known amounts of added bilirubin. Irrigation of the transplants with saline, protein, and sugar resulted in moderate (40%) lowering of serum total and indirect bilirubin levels. Fat was significantly more effective, lowering mean total bilirubin levels from 9.6 +/- 0.4 to 1.6 +/- 0.2 mg/dl at 6 weeks. After this time, bilirubin levels increased slightly. Bile salts were slightly less effective, lowering bilirubin levels at 6 weeks by only 75%. However, this effect persisted and at 8 weeks levels averaged 2.4 +/- 0.2 mg/dl. Conjugating enzyme activity in the transplants increased from 1.4 +/- 0.3 to 2.5 +/- 0.5 mg bilirubin conjugated/mg tissue/hr. Luminal fats and bile salts appear to augment enzyme-induced bilirubin conjugation in heterotopic jejunal transplant recipients.

Quantitative assessment of cytokines (GRO alpha and IL-10) in human seminal plasma during genitourinary inflammation

PROBLEM

Mechanisms involved in infertility due to genitourinary (GU) inflammation are unknown. The production of pro-inflammatory (GRO alpha) and anti-inflammatory (IL-10) cytokines in seminal plasma is monitored in this study.

METHOD

GRO alpha, IL-10, and granulocyte elastase were evaluated in semen from I) normal, II) infertile patients, and III) infertile patients with leukocytospermia.

RESULTS

GRO alpha in infertile patients with GU inflammation was 1.5-fold higher compared to group II and 2.5-fold higher compared to group I patients. The IL-10 was higher in group III than the other two groups. A positive correlation was observed between granulocyte elastase and GRO alpha in all groups. Group III patients exhibited poor sperm parameters.

CONCLUSIONS

A shift towards increased production of pro-inflammatory chemokine GRO alpha may have a potential role in male infertility associated with GU inflammation.

Role of oxidative stress and antioxidants in male infertility

Oxygen toxicity is an inherent challenge to aerobic life, including spermatozoa, the cells responsible for propagation of the species. How this toxicity affects the spermatozoan in its interactions with the ovum is still unknown. An increase in oxidative damage to sperm membranes, proteins, and DNA is associated with alterations in signal transduction mechanisms that affect fertility. Recent evidence suggests that spermatozoa and oocytes possess an inherent but limited capacity to generate ROS to aid in the fertilization process. Though a variety of defense mechanisms encompassing antioxidant enzymes (SOD, catalase, and GSH peroxidase and reductase), vitamins (E, C, and carotenoids), and biomolecules (GSH and ubiquinol) are available, a balance of the benefits and risks from ROS and antioxidants appears to be necessary for the survival and functioning of spermatozoa. An assay system for the evaluation of OSS needs to be developed. Such an assay will assist the clinician in the assessment of fertility status of both male and female partners. The determination of this OSS value will also theoretically identify the subgroups of responders and nonresponders to any putative antioxidant therapy. Though the therapeutic use of antioxidants appears attractive, clinicians need to be aware of exaggerated claims of antioxidant benefits by various commercial supplements for fertility purposes until proper multicenter clinical trial have been completed.

Oxidative stress and interleukins in seminal plasma during leukocytospermia

OBJECTIVE

To quantify the levels of reactive oxygen species, superoxide dismutase (SOD), and interleukins (IL) 2 and 8 in seminal plasma of infertile patients as well as to examine the possible relationship between oxidative stress and proinflammatory cytokines.

DESIGN

Semen collected from normal fertile donors, infertile men without symptoms of genitourinary (GU) inflammation, and infertile men with symptoms of infection-inflammation of the GU tract was evaluated for the levels of granulocyte elastase, reactive oxygen species, SOD, IL-2, and IL-8. Any correlation between the levels of reactive oxygen species and other parameters in these population was analyzed statistically.

RESULTS

Significantly high levels of granulocyte elastase (18.32 +/- 1.52 U/L), reactive oxygen species (6 x 10(5) cpm), IL-8 (3.7 +/- 0.10 microgram/L), and IL-2 (18.32 +/- 1.47 ng/L) were observed in semen of infertile patients with leukocytospermia compared with the other two groups. In leukocytospermic samples, the activity of SOD was significantly lower (624.89 +/- 41.16 NU/mL) compared with nonleukocytospermic samples (787.85 +/- 24.26 NU/mL) or fertile donors (816.29 +/- 50.16 NU/mL). A significant positive correlation was observed between the levels of reactive oxygen species and IL-8.

CONCLUSIONS

These findings suggest that increased oxidative stress observed during leukocytospermia may modulate the level of proinflammatory cytokines. The increased oxidative stress may be due to a defect in the reactive oxygen species scavenging system.

Sperm-damaging effects of electric current: possible role of free radicals

The generation of reactive oxygen species (ROS) and sperm damage was evaluated in (a) samples obtained during electroejaculation (EE) of men with spinal cord injury and (b) in electrolyzed HAM's F-10 medium subjected to electric current in vitro. Chemiluminescence data showed a significant increase in ROS in the ejaculates (6 x 10(7) photons/ml) collected immediately after EE and in the electrolyzed medium (3 to 7 x 10(6) photons/ml) when compared to the control (4 to 7 x 10(4) photons/ml). Incubation of normal human sperm with the electrolyzed medium resulted in a significant threefold decrease in percent motility and a twofold decrease in percent viability. Sperm subjected to direct electric stimulation in vitro exhibited a significant twofold decrease in percent motility and percent viability. Superoxide dismutase (SOD) activity decreased significantly in sperm subjected to direct electric current in comparison to the control or the sample incubated with electrolyzed medium. These studies indicate that in vitro and in vivo electrical stimulation generate reactive oxygen species and affect SOD activity, which in part are responsible for decreased sperm motion and viability.

Spermicidal activity of an antifungal saponin obtained from the tropical herb Mollugo pentaphylla

The ethyl acetate fraction of Mollugo pentaphylla, a tropical herb, contains an antifungal saponin (mollugogenol-A). We report here the spermicidal effects of this saponin. Washed sperm (> 100 x 10(6) with > 50% motility) from normal volunteers were incubated with varying concentrations (0-300 micrograms/ml) of mollugogenol-A at 30 degrees C. Sperm motility, velocity and viability were assessed at 0, 30, 60 minutes both manually and by using computer assisted semen analysis (CASA). Samples collected at 0 and 60 minutes were evaluated for membrane lipid peroxidation, superoxide dismutase (SOD) activity and transmission electron microscopy. A dose- and time-dependent effect of this saponin on sperm motion and viability was observed. The maximal spermicidal effect (4-5 fold decrease in motility and viability) was observed with 300 micrograms/ml dose of saponin. A three-fold increase in sperm membrane lipid peroxidation with corresponding inhibition of SOD activity were observed after 60 minutes incubation with this spermicidal agent. Transmission electron microscopy of saponin-treated samples revealed significant damage to the sperm membrane in both head and tail regions, and the acrosomal membranes were notably swollen and disrupted. These results indicate that this natural saponin has a potential spermicidal effect besides its known antifungal activity. The likely mechanism of its action involves sperm membrane damage by increased lipid peroxidation.

Time course of hydrogen peroxide induced changes in the lipid peroxidation of human sperm membranes

The present study evaluates the changes in sperm motility due to H202 induced membrane damage. Washed human sperm suspended in HAM's F-10 (20-30 x 10 6/ml) were incubated (37 degrees Celsius) with varying concentrations (0-0.05%) of H202 for up to 15 minutes. Sperm were analyzed for % motility, % viability, the ratio of cholesterol to phospholipids (C/PL), and the degree of lipid peroxidation (LPO). Motility was monitored manually and viability was evaluated by the Eosin Y staining method. Total lipids were extracted with chloroform:methanol (1:2) and used in colorimetric determination of cholesterol and phospholipid contents (mcmol/106 sperm). Lipid peroxidation was measured by the production of malondialdehyde (nmol MDA/108 sperm). The results (mean +or- SEM, n=8) indicate a dose a time-dependent effect on % motility during the 15 minute incubation period. In comparison to control (8 +or- 4%), samples incubated with 0.01% H202 exhibited a 25 +or- 3% decrease in % motility, while a complete loss of motility was observed with 0.05% H202. No significant differences in decrease in sperm viability were observed between control (211 +or- 4) and H202 (0.01%) treated samples (14 +or- 2%). An increase of (54 +or- 5%) in lipid peroxidation was observed with 0.01% H202, as compared with an 18 +or- 1% increase in control samples at 15 minutes. The C/PL ratio increased by 46 +or- 4% at 15 minutes in H202 treated samples while showing a 34.3% decrease in control samples. H202 inhibited sperm motility while increasing membrane LPO and C/PL, without altering sperm viability. It would appear that lipid peroxidation and alteration of sperm membrane composition lead to the loss of sperm motility.

Pre-clinical toxicity of IDPH-791: a new centrally acting muscle relaxant in rats

IDPH-791, a novel centrally acting muscle relaxant, in doses up to 500 mg/kg (po) for 14 days did not result in any appreciable adverse effect on body weight gain, food or water consumption including biochemical and haematologica parameters in rats. Variations observed in the biochemistry and haematology were either comparable to controls or were within normal limits.

Role of calcium in prolactin analgesia

The effect of calcium chloride and nifedipine on prolactin-(PRL) induced analgesia was studied by chemical assay and compared with other analgesics like morphine, thyrotrophin-releasing hormone (TRH) and clonidine. Nifedipine potentiated the analgesic effect of PRL similar to morphine while that of clonidine and TRH remained unaltered. Further, calcium chloride administration antagonized the analgesic effect of PRL and of morphine. These data suggest that PRL, similar to morphine, may alter calcium movements across the membrane to produce analgesia.