Susceptibility of Chlamydia trachomatis to excipients commonly used in topical microbicide formulations

Commonly used "inactive" pharmaceutical excipients were tested in a previously developed minimum cidal concentration assay to assess their ability to kill Chlamydia trachomatis topically. Sixteen excipients were evaluated in these studies under various conditions. A range of activities was found among the excipients that could be tested in our assay system.

Storage of platelets in additive solution for up to 12 days with maintenance of good in-vitro quality

BACKGROUND

Storage of PLT concentrates (PCs) may be extended beyond 5 days, provided in-vitro and in-vivo variables allow longer storage and bacterial screening is performed. The aim of this study was to examine in-vitro storage characteristics of PCs in various storage solutions: plasma only, or mixtures of plasma with PAS-II, PAS-III, PAS-IIIM, and Composol.

STUDY DESIGN AND METHODS

PCs from five pooled buffy-coats and WBCs reduced by filtration were stored in 1.3-L butyryl-tri-hexyl-citrate-plasticised PVC containers. First, a paired comparison was made between PAS-II and Composol, with 35-percent final plasma concentration (n = 10). Then, plasma, PAS-III with 30-percent plasma, PAS-IIIM with 20- and 30-percent plasma, and Composol with 20 and 30-percent final plasma concentration were compared (n = 5 pairs). Finally, 50 PCs in Composol with 35-percent final plasma concentration were studied.

RESULTS

PCs in PAS-II or Composol had a mean +/- SD pH of 6.95 +/- 0.09 and 6.96 +/- 0.08 at Day 12, respectively. For PCs in PAS-IIIM and Composol with 30-percent final plasma concentration, pH on Day 7 was 7.00 +/- 0.02 and 6.83 +/- 0.05. With 20-percent final plasma concentration, pH was 6.98 +/- 0.02 and 6.81 +/- 0.03 for PAS-IIIM and Composol, respectively. PCs in PAS-III with 30-percent plasma had a pH on Day 7 of 6.87 +/- 0.03, whereas PCs in 100-percent plasma had a pH of 7.05 +/- 0.03. PCs in Composol with 35-percent plasma maintained pH greater than 6.8 in 48 of 50 of the units (96%), averaging 7.00 +/- 0.10 on Day 8.

CONCLUSION

In-vitro quality of PCs in AS with at least 35-percent plasma can be maintained for 7 to 12 days after collection.

Conjunctival Proinflammatory and Proapoptotic Effects of Latanoprost and Preserved and Unpreserved Timolol: An Ex Vivo and In Vitro Study

PURPOSE

To compare the toxicity of latanoprost and preserved and unpreserved timolol on conjunctival cells. Expression of inflammatory markers and MUC5AC-related mucin production were evaluated by impression cytology in a case-control ex vivo study. The proapoptotic effect of the same drugs was also evaluated in vitro in a conjunctival cell line and compared with that of benzalkonium chloride (BAC).

METHODS

Impression cytology (IC) specimens were obtained from a series of normal subjects and from patients with glaucoma treated for at least 1 year with latanoprost eye drops or preserved or unpreserved timolol. All groups were comparable in age and duration of treatment. Expression of HLA-DR, intercellular adhesion molecule (ICAM)-1, and mucin was evaluated in a masked manner by flow cytometry. For the in vitro study, a human conjunctiva-derived cell line was treated with 0.02% BAC-containing latanoprost or timolol, unpreserved timolol, or 0.02% BAC alone for 15 minutes, followed or not by 4 or 24 hours of cell recovery in normal medium. Cell viability and chromatin condensation were evaluated using microplate cold light cytofluorometry with the neutral red and the Hoechst 33342 tests, respectively. The Hoechst-neutral red ratio was defined for the apoptosis assay, and cytoskeleton changes were assessed by confocal microscopy.

RESULTS

No difference was found between normal eyes and those receiving unpreserved timolol. Preserved latanoprost and timolol significantly increased the inflammatory marker expression and decreased MUC5AC expression, but to a significantly higher extent in the preserved timolol group compared with latanoprost. In vitro, 0.02% BAC-containing timolol and latanoprost triggered conjunctival cell apoptosis-however, to a significantly lesser extent than did 0.02% BAC alone. Unpreserved timolol did not cause any cell toxicity.

CONCLUSIONS

These ex vivo and in vitro studies demonstrate that BAC-containing latanoprost and timolol exhibit higher proinflammatory and proapoptotic effects on conjunctival cells than does unpreserved timolol. Latanoprost caused less toxicity, however, than preserved timolol, and both drugs were less toxic than BAC alone. These results suggest a potential protective effect of the prostaglandin analogue and to a lesser extent of timolol against the toxicity of BAC in conjunctival cells.

Activation of methionine synthase by insulin-like growth factor-1 and dopamine: a target for neurodevelopmental toxins and thimerosal

Methylation events play a critical role in the ability of growth factors to promote normal development. Neurodevelopmental toxins, such as ethanol and heavy metals, interrupt growth factor signaling, raising the possibility that they might exert adverse effects on methylation. We found that insulin-like growth factor-1 (IGF-1)- and dopamine-stimulated methionine synthase (MS) activity and folate-dependent methylation of phospholipids in SH-SY5Y human neuroblastoma cells, via a PI3-kinase- and MAP-kinase-dependent mechanism. The stimulation of this pathway increased DNA methylation, while its inhibition increased methylation-sensitive gene expression. Ethanol potently interfered with IGF-1 activation of MS and blocked its effect on DNA methylation, whereas it did not inhibit the effects of dopamine. Metal ions potently affected IGF-1 and dopamine-stimulated MS activity, as well as folate-dependent phospholipid methylation: Cu(2+) promoted enzyme activity and methylation, while Cu(+), Pb(2+), Hg(2+) and Al(3+) were inhibitory. The ethylmercury-containing preservative thimerosal inhibited both IGF-1- and dopamine-stimulated methylation with an IC(50) of 1 nM and eliminated MS activity. Our findings outline a novel growth factor signaling pathway that regulates MS activity and thereby modulates methylation reactions, including DNA methylation. The potent inhibition of this pathway by ethanol, lead, mercury, aluminum and thimerosal suggests that it may be an important target of neurodevelopmental toxins.

Microorganisms growth in endodontic citric-acid solutions with and without microbiological stabilizer

The purpose of this study was to determine if citric-acid solutions for endodontic use can become contaminated and if the addition of a microbiological stabilizer to the acid would modify this situation. Five types of microorganisms were inoculated in tubes containing 10% citric-acid solutions, pH 1.8 (group A1), and 10% solution, pH 1.8, combined with 0.1% sodium benzoate (group A2). The results demonstrated that solutions of group A1 were contaminated with Candida albicans in 100% of the tubes, Escherichia coli in 80%, and Enterococcus faecalis in 50%. When stabilizer was added (group A2), C. albicans grew in only 30% of tubes and all bacterial species were neutralized.

Comparison of the short-term effects on the human corneal surface of topical timolol maleate with and without benzalkonium chloride

PURPOSE

To compare the short-term effects of timolol maleate with and without preservative (0.005% benzalkonium chloride) on pre-corneal tear film stability and corneal epithelial barrier function.

SUBJECTS AND METHODS

The study population consisted of 20 healthy volunteers. To obtain baseline values, 7 days before the experiment the non-invasive breakup time of the pre-corneal tear film was measured using a tear specular microscope; corneal fluorescein uptake was measured with a fluorophotometer. Unpreserved or preserved 0.5% timolol was applied to one eye; the contralateral eye was exposed to the other drug. At 30 minutes after instillation, the pre-study tests were repeated.

RESULTS

Preserved timolol did, while unpreserved timolol did not, significantly reduce the non-invasive breakup time from the baseline values (baseline and post-exposure values 11.4 and 6.8 seconds, respectively, P = 0.008 for preserved timolol, and 11.7 vs. 11.0 seconds, P = 0.55 for unpreserved timolol). Corneal fluorescein uptake, on the other hand, was significantly increased upon exposure to either preserved or unpreserved timolol (baseline and post-exposure values 37.5 and 82.0 ng/ml, P < 0.001 for preserved timolol, and 35.4 vs. 57.6 ng/ml, P < 0.001 for unpreserved timolol). Preserved timolol exerted the greater effect (P = 0.028).

CONCLUSIONS

Exposure to preserved timolol resulted in significant instability in the pre-corneal tear film. Moreover, it disrupted the corneal epithelial barrier function to a greater degree than unpreserved timolol. The elimination of preservatives may be desirable in efforts to protect the integrity of the corneal surface and its interaction with the tear film.

Direct Dialysis Quantification: Investigation of the Impact of Dialysate Preservation Techniques on Solute Assays

<i>Aims:</i> Urease-producing microorganisms may lower urea nitrogen (UN) during dialysate-side dosing. We investigated the impact of 3 proven preservatives (acetic acid, ceftazidime, thimerosal) on UN concentration, and the concentrations of creatinine (CR) and β₂-microglobulin (β₂M). <i>Methods:</i> The UN, CR and β₂M concentrations were assayed in 3 separate aliquots from 20 spent dialysate samples (ceftazidime, 125 mg/l, or 1% thimerosal, 1 ml/l, vs. control). The β₂M concentration was assayed in 10 further spent dialysate collections (concentrated glacial acetic acid, 5 ml/l, vs. control). Solute concentrations were compared with the concordance correlation coefficient (r_c). <i>Results:</i> Ceftazidime and thimerosal had little effect on the concentrations of UN and CR (r_c >0.97). For the β₂M concentration, agreement remained good (r_c >0.96) for ceftazidime and thimerosal (although the former tended to lower concentrations) but acetic acid was less optimal (r_c = 0.893). <i>Conclusions:</i> Ceftazidime and thimerosal may be used as dialysate preservatives without affecting the UN or CR concentrations. Thimerosal is to be preferred when studying β₂M. Acetic acid produces unacceptable inaccuracy when measuring β₂M.

[Use of impedance test for testing effectiveness of drug preservatives]

Pharmacopoeias contain preservation efficacy test for estimating antimicrobial activity of chemical compounds added to pharmaceutical preparations in multidose containers in order to inhibit bioburden growth. This method involves the treating of preserved products with bacteria and yeast cells and monitoring the survival of microorganisms through the specified time periods up to 28 days. The last stage of assay--incubation and colony counting--is very time consuming. Recent advance in technology enables faster and more convenient detection in comparison to traditional methods. Impedance method is based on the principle that conductance and capacitance of cultivation medium increases when bacteria grow and metabolize, Impedance time detection is inversely proportional to initial bacterial population. Six different products were utilised throughout the study. The calibration curves were calculated for each of the tested strains by comparison between standard plate count method and detection time measured in Bactometer system. In our study log reduction calculated in alternative method were similar to those obtained in plate count assay. All of the tested preparations, except one, exhibited acceptable activity against bacteria and fungi and meet the pharmacopoeal requirements. The studies indicated a positive correlation between standard plate count results and impedance reading. The procedure with the usage of Bactometer, provides a rapid and accurate system for the determination of bacterial content.

In vitro effects of preserved and unpreserved antiglaucoma drugs on apoptotic marker expression by human trabecular cells

BACKGROUND

The mechanisms of trabecular cell loss in glaucoma patients are poorly understood. In order to determine whether drug-induced apoptosis could be one of the mechanisms by which trabecular cells die in glaucoma, we evaluated the effect of benzalkonium-preserved (BAC+) or preservative-free (BAC-) antiglaucoma medications on apoptotic marker expression by cultured human trabecular meshwork (HTM) cells.

METHODS

Normal and glaucomatous trabecular cell lines were treated for 15 min with antiglaucoma drugs (1/100 and 1/10 dilutions): timolol BAC+ or BAC-, betaxolol BAC+ or BAC-, latanoprost BAC+ or pure BAC. Apo2.7 expression, annexin V binding and DNA content were evaluated by flow cytometry and confocal microscopy.

RESULTS

Results obtained in the two cell lines were similar for all tested drugs and criteria. In a 1/100 dilution, unpreserved beta-blockers had no apoptotic effect, preserved beta-blockers and latanoprost significantly increased Apo2.7 expression only, while BAC significantly increased all three apoptotic markers. When tested in a 1/10 dilution, all drugs except unpreserved timolol triggered a 2- to 3.5-fold increase in apoptotic features, whereas up to 95% of the cells underwent apoptosis upon treatment with BAC (representing a 9-fold increase over the background level).

CONCLUSION

At concentrations higher than those supposed to be found in the aqueous humor after instillation (1/100 dilution), unpreserved beta-blocker exhibited no proapoptotic activity on HTM cells in vitro. Benzalkonium-containing beta-blockers and prostaglandin analogue triggered mild expression of one out of three apoptotic markers, while the pro-apoptotic effect observed with BAC appeared to be largely hindered by active compounds in the preserved eyedrops.

Effects of blood product storage protectants on blood coagulation1 1The opinions expressed herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of the Army or the Department of Defense

The ever-increasing demand for blood products challenges scientists to develop new and more effective techniques for their preservation. The progress of these novel preservation technologies uses a wide variety of cryoprotectant, lyoprotectant, and other preservatives, which will need to be explored and assessed for their biological effects during blood product formulation. The leading factor in protectant selection is for their ability to provide superior preservation for a particular blood product. We believe that such protectants used in blood product development should also be evaluated for their ability to preserve normal hemostasic mechanisms. In this review, high-molecular-weight cryoprotectants, lyoprotectants, polyols, amino acids, antioxidants, and surfactants, used because of their protective properties, were evaluated for their possible role in relation to their effect on normal hemostatic mechanisms.

[Flow cytometric analysis of HLA-DR, IL-6 and IL-8 expression by conjunctival epithelial cells from patients with prolonged topical antiglaucoma treatments]

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.

Rapid stimulation of free glucuronate formation by non-glucuronidable xenobiotics in isolated rat hepatocytes

Vitamin C synthesis in rat liver is enhanced by several xenobiotics, including aminopyrine and chloretone. The effect of these agents has been linked to induction of enzymes potentially involved in the formation of glucuronate, a precursor of vitamin C. Using isolated rat hepatocytes as a model, we show that a series of agents (aminopyrine, antipyrine, chloretone, clotrimazole, metyrapone, proadifen, and barbital) induced in a few minutes an up to 15-fold increase in the formation of glucuronate, which was best observed in the presence of sorbinil, an inhibitor of glucuronate reductase. They also caused an approximately 2-fold decrease in the concentration of UDP-glucuronate but little if any change in the concentration of UDP-glucose. Depletion of UDP-glucuronate with resorcinol or d-galactosamine markedly decreased the formation of glucuronate both in the presence and in the absence of aminopyrine, confirming the precursor-product relationship between UDP-glucuronate and free glucuronate. Most of the agents did not induce the formation of detectable amounts of glucuronides, indicating that the formation of glucuronate is not due to a glucuronidation-deglucuronidation cycle. With the exception of barbital (which inhibits glucuronate reductase), all of the above mentioned agents also caused an increase in the concentration of ascorbic acid. They had little effect on glutathione concentration, and their effect on glucuronate and vitamin C formation was not mimicked by glutathione-depleting agents such as diamide and buthionine sulfoximine. It is concluded that the stimulation of vitamin C synthesis exerted by some xenobiotics is mediated through a rapid increase in the conversion of UDP-glucuronate to glucuronate, which does not apparently involve a glucuronidation-deglucuronidation cycle.

Involvement of oxidative stress in apoptosis induced by a mixture of isothiazolinones in normal human keratinocytes

A 3:1 combination of 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and 2-methyl-4-isothiazolin-3-one (MI) is widely used to preserve cosmetic products. We show here that CMI/MI induced apoptosis in normal human keratinocytes (NHK) as at low concentrations (0.001-0.05% documented by subdiploid DNA content and phosphatidylserine exposure, while at the highest concentration (0.1% as supplied, 15 p.p.m.) the response was necrosis. Various molecular events accompanied the cytotoxic effects of CMI/MI. Generation of ROS and hyperpolarization of mitochondrial transmembrane potential (DeltaPsim) were early events, followed by increased Fas expression and activation of caspase-8, and then activation of caspase-3 and -9. The drop in DeltaPsim occurred only later in the cell death pathway, when NHK showed signs of apoptosis. Pretreatment of cells for 2 h with the redox-active agent N-acetyl-L-cysteine conferred complete protection against the CMI/MI-induced cytotoxic effects, DeltaPsim loss, and apoptosis. The pan-caspase inhibitor Z-Val-Ala-Asp(OMe)-CH2F blocked the CMI/MI-induced apoptosis without preventing ROS generation and the drop in DeltaPsim. These results indicate that the generation of ROS plays an important part in mediating apoptosis and necrosis associated with CMI/MI treatment. This new aspect of the in vitro toxicity of CMI/MI may provide important information about the relationship between the preservative's in vitro apoptotic activity and its in vivo toxicity.

[Inhibition effect of merthiolate used as vaccines preservative on the oxygen-dependent metabolism of neutrophil granulocytes]

The influence of the newly developed complex vaccine Pyopol, containing the antigens of opportunistic microorganisms and polyoxydonium used as immunomodulator, on the oxygen-dependent metabolism of neutrophils was studied. The study revealed that the main components of the vaccine, both individually and in association, did not change cellular activity in the range of concentrations used in this study. The inhibition of the oxygen-dependent metabolism of neutrophil granulocytes in the presence of native or weakly diluted vaccine occurred due to the cytotoxic effect of thimerosal used as preservative.

Stabilization of penicillinase-hapten conjugate for enzyme immunoassay

The influence of various additives, such as organic solvents, polyhydric alcohols, salts, polymers, and cross-linker, on the stability and storage ability of penicillinase-morphine conjugate was studied in liquid and solid (freeze dried) states. The results of these experiments showed that using low concentrations of CaCl2 (0.1-0.2%) could stabilize enzyme activity in both states for more than seven months. The immunoreactivity of antigen toward the antibody did not change significantly. However, a cross-linker such as glutaraldehyde and various additives such as dimethylsulfoxide, glycerol, polyethylene glycol, gelatin, dextran, ammonium sulfate, lactose, and sucrose did not have any effect on stability. In addition, it was found that the presence of lactose and sucrose in the lyophilization procedure gives a significant amount of protection to the enzyme, which could last for a period of seven months and preserve almost 95% of the enzyme activity, as well as immunoreactivity of the tracer molecule.

Human lens epithelial cell damage and stimulation of their secretion of chemical mediators by benzalkonium chloride rather than latanoprost and timolol

OBJECTIVE

To investigate the effects of latanoprost, timolol maleate, and benzalkonium chloride on cell damage and induction of the secretion of chemical mediators of stress and wound healing by human lens epithelial cells in culture.

METHODS

Cells from a human lens epithelial cell line (SRA01/04) were cultured in Dulbecco minimum essential medium supplemented with 5% fetal bovine serum. The amounts of latanoprost (50 micro g/mL), timolol maleate (5 mg/mL), or benzalkonium chloride (200 micro g/mL) used in eyedrops, and x10 to x1000 dilutions thereof, were added to the medium. After 7 days' culture, cell morphological changes were assessed using phase-contrast microscopy, and cell-free culture supernatants were collected for prostaglandin E2 (PGE2), interleukin 1alpha (IL-1alpha), and interleukin 6 (IL-6) iodine I 125 radioimmunoassay, enzyme-linked immunosorbent assay, and chemiluminescent enzyme immunoassay, respectively.

RESULTS

All cells that were cultured with the concentrations of latanoprost, timolol, or benzalkonium chloride used in eyedrops detached from the culture dish and died within 3 days. At a x10 dilution of latanoprost or timolol or a x100 dilution of benzalkonium chloride, no proliferation or elongation of the cells was observed. Secretions of PGE2, IL-1alpha, and IL-6 at x10 dilutions of latanoprost or timolol were 3 to 77 times higher than in controls, whereas they were 190 to 305 times higher at a x180 dilution of benzalkonium chloride. The amounts of these soluble mediators in culture supernatants depended on the dose of latanoprost, timolol, or benzalkonium chloride added.

CONCLUSION

Our results indicate that benzalkonium chloride, used as the preservative in eyedrops containing latanoprost or timolol, is the agent most damaging to lens epithelial cells and most strongly stimulates the expression of soluble chemical mediators in these cells.

Effects of nasal saline spray on human neutrophils

BACKGROUND

Nasal saline spray (NSS) used in the treatment of rhinitis and sinusitis often contains the preservative benzalkonium chloride (BKC). Previous studies have shown that corticosteroid nasal sprays and topical decongestants containing BKC damage respiratory mucosa, decrease mucociliary activity, and inhibit neutrophil functions in vitro.

OBJECTIVE

To evaluate the effects of NSS with BKC on human neutrophils.

DESIGN

Prospective, basic science observations.

METHODS

Human neutrophils were exposed to NSS with BKC or to phosphate-buffered saline (PBS) at varying times and concentrations. The cells were examined for morphologic changes by light microscopy and for viability as determined by trypan blue exclusion. Lactate dehydrogenase levels were measured to quantify neutrophil cell lysis. In vivo morphologic changes were studied in neutrophils obtained from the oral mucosa in human volunteers who rinsed their mouths with NSS or PBS.

RESULTS

Neutrophils exposed to NSS concentrations as low as 15% showed near-total cell lysis, and neutrophils exposed to 20% NSS demonstrated no cell viability by trypan blue staining. Phosphate-buffered saline-exposed cells were unaffected. The release of lactate dehydrogenase from lysed neutrophils increased sharply at NSS concentrations higher than 10% but remained stable in PBS-exposed cells. All neutrophils isolated from NSS oral rinses were lysed, while a mean of 78% of neutrophils from PBS rinses showed normal morphologic structure.

CONCLUSIONS

Nasal saline spray with BKC is toxic to human neutrophils even at concentrations far lower than those found in commercially available preparations. Saline solutions without BKC appear to be safer alternatives, and additional studies are needed to determine the clinical significance of these findings.

Investigation on the inhibition of Campylobacter jejuni growth with the applications of some preservatives, medicines, herbs and herb preparations

The aim of this study was to determine the influence of chosen preservatives, medicines, herbs and herb preparations on 39 Campylobacter jejuni strains, which were isolated from fresh poultry carcasses. De-Nol and ventrisol were used in the original concentration. Propolis, propolan, artecholin and aukalen were of pharmacies origin. The rest of substances examined were 10% water solutions. Out of 11 substances examined, potassium sorbate, sodium benzoate, De-Nol and ventrisol exerted the strongest inhibitory action on Campylobacter jejuni.

Development of a multidose formulation for a humanized monoclonal antibody using experimental design techniques

The purpose of this study was to identify optimal preservatives for a multidose formulation of a humanized monoclonal antibody using experimental design techniques. The effect of antimicrobial parenteral preservatives (benzyl alcohol, chlorobutanol, methylparaben, propylparaben, phenol, and m-cresol) on protein stability was assessed using size-exclusion chromatography, differential scanning calorimetry, right-angle light scattering, UV spectroscopy, and potency testing using a cell-based fluorescence-activated cell sorting method. A quick, cost-effective preservative screening test was designed. Combinations of preservatives were examined using an I-optimal experimental design. The protein was most stable in the presence of methylparaben and propylparaben, and was compatible with benzyl alcohol and chlorobutanol at low concentrations. Phenol and m-cresol were not compatible with the protein. The I-optimal experimental design indicated that as an individual preservative, benzyl alcohol was promising. The model also indicated several effective combinations of preservatives that satisfied the antimicrobial efficacy and physical stability constraints. The preservative screening test and the experimental design approach were effective in identifying optimal concentrations of antimicrobial preservatives for a multidose protein formulation; (1) benzyl alcohol, and (2) the combination of methylparaben and chlorobutanol were screened as potential candidates to satisfy the regulatory requirements of various preservative efficacy tests.

Performance of contact lens disinfecting solutions against Pseudomonas aeruginosa in the presence of organic load

PURPOSE

Contact lens wearers can become noncompliant with lens disinfection procedures. The purpose of this study was to evaluate multipurpose contact lens disinfecting solutions in the presence of organic soil.

METHODS

OPTI-FREE EXPRESS and three products preserved with polyhexamethylene biguanide (PHMB) were inoculated with three strains of Pseudomonas aeruginosa in organic soil. Surviving bacteria were counted at various time points, using the ISO 14729 standard method.

RESULTS

Results indicated that OPTI-FREE EXPRESS was efficient in the presence of organic soil and achieved a reduction of almost 6 log. The other products were less effective under the test conditions and failed to achieve 3-log reduction of the bacteria. These products also seemed to lose activity after time, allowing surviving bacteria to multiply. Conversely OPTI-FREE EXPRESS maintained high activity for the entire 72 hours of the study.

CONCLUSIONS

The results indicate that OPTI-FREE EXPRESS would remain highly efficient in the case of noncompliance with disinfection procedures.

Redox regulation of calcium release in skeletal and cardiac muscle

In skeletal and cardiac muscle cells, specific isoforms of the Ryanodine receptor channels mediate Ca2+ release from the sarcoplasmic reticulum. These channels are highly susceptible to redox modifications, which regulate channel activity. In this work, we studied the effects of Ca2+ (endogenous agonist) and Mg2+ (endogenous inhibitor) on the kinetics of Ca2+ release from sarcoplasmic reticulum vesicles isolated from skeletal or cardiac mammalian muscle. Native skeletal vesicles exhibited maximal stimulation of release kinetics by 10-20 microM [Ca2+], whereas in native cardiac vesicles, maximal stimulation of release required only 1 microM [Ca2+]. In 10 microM [Ca2+], free [Mg2+] < 0.1 mM produced marked inhibition of release from skeletal vesicles but free [Mg2+] < or = 0.8 mM did not affect release from cardiac vesicles. Incubation of skeletal or cardiac vesicles with the oxidant thimerosal increased their susceptibility to stimulation by Ca2+ and decreased the inhibitory effect of Mg2+ in skeletal vesicles. Sulfhydryl-reducing agents fully reversed the effects of thimerosal. The endogenous redox species, glutathione disulfide and S-nitrosoglutathione, also stimulated release from skeletal sarcoplasmic reticulum vesicles. In 10 microM [Ca2+], 35S-nitrosoglutathione labeled a protein fraction enriched in release channels through S-glutathiolation. Free [Mg2+] 1 mM or decreasing free [Ca2+] to the nM range prevented this reaction. Possible physiological and pathological consequences of redox modification of release channels on Ca2+ signaling in heart and muscle cells are discussed.

Preservative properties of Calamintha officinalis essential oil with and without EDTA

AIMS

This study was focused on the preserving properties of Calamintha officinalis essential oil, a plant known for its diaphoretic, expectorant and aromatic properties.

METHODS AND RESULTS

The commercial aerial parts of C. officinalis Moench were hydrodistilled and the essential oil analysed by Gas chromatography/Electron impact mass spectrometry (GC/EIMS). The inhibition efficacy of this essence, alone (0.5 and 1.0% v/v) and in combination with 2.0 mM EDTA, was assayed, in culture medium and in cetomacrogol cream, using preservative efficacy testing against standard microrganisms (E. coli ATCC 25922, Ps. aeruginosa ATCC 9027, Staph. aureus ATCC 6538P, C. albicans ATCC 10231 and A. niger ATCC 16404). C. officinalis essential oil in cetomacrogol cream with EDTA showed long-lasting antimicrobial activity, satisfying the European Pharmacopoeia Commission (E. P.) criteria.

CONCLUSION

C. officinalis essential oil could have a potential for a future use as a cosmetic preservative.

IMPACT OF THE STUDY

To find natural compounds with antimicrobial activity which could be alternatives to the synthetic chemical preservatives.

Vasoactive properties of lignocaine administered by iontophoresis in human skin

The vasoactivity of lignocaine has an important influence on its clinical efficacy and systemic vascular absorption. The aim of this study was to evaluate its vasoactive properties when administered by the non-invasive technique of iontophoresis. We used laser Doppler imaging to measure the forearm skin blood flow responses of seven healthy young males to iontophoretic delivery of two preparations of 20 g/l of lignocaine hydrochloride, one containing the preservatives methylparaben and propylparaben and one without. The subjects were blind to the order of drug administration, and we assessed analgesia at the sites using a pinprick test. Delivery of both preparations of (positively charged) lignocaine under the anode caused demonstrable analgesia, but no change in skin blood flow. An increase in perfusion was measured, however, when the preservative-containing preparation was administered under the cathode. There was little or no response to the solution without preservatives, although the difference in response between the two preparations was not statistically significant (P =0.063). Although there were no vasoactive effects of lignocaine at the relatively low dose used in the present study, our results suggest that the preservatives methylparaben and propylparaben are the most likely cause of the vasodilatation that we observed under the cathode, and may therefore have a significant influence on the vasoactivity of this preparation when administered by injection. Both are negatively charged in solution and have been reported to possess vasodilator properties. It might be worth considering the use of alternative, non-vasoactive preservatives in local anaesthetic preparations, or avoiding the use of additives altogether, when this is feasible.

A new platelet preservative

A new platelet preservative, ViaCyte trade mark (balanced salt solution, physiological buffer, D-ribose, bovine serum albumin, D-glucose, sterile water) was tested against the presently used storage solution (citrate-phosphate-dextrose; CPD) and results revealed that ViaCyte demonstrated added protection for platelets during storage-induced activation. Following five days of storage at room temperature, only 12.2% of platelets stored in ViaCyte exhibited P-selectin expression at rest and, upon thrombin challenge, 64.2% were activated, an increase of 42%. In control platelets (platelets stored in CDP), 44.4% were activated due to storage-induced lesions, and thrombin stimulation resulted in 47.9% P-selectin expression, an increase of only 2.5%. ViaCyte storage maintained the resting state and preserved platelet function, making more platelets available for activation upon agonist challenge. This preliminary study demonstrated that the presently used standard preservative does not offer protection from storage-induced lesions. Partially dysfunctional platelets do not contribute significantly to hemostasis in vivo and play little role, if any, in clot retraction and wound healing processes.