Analysis of creams

The uv absorbing properties of the components of the cream bases as described in the Formulary of the Dutch Pharmacists were investigated. Directuv spectrophotometric determinations without any clean-up steps appeared to be possible for a number of drugs (e.g. tripelennamine HCl, tretinoin, salicylic acid, methyl salicylate, resorcinol, clioquinol), with the help of a solvent mixture in which the cream samples dissolved completely to yield clear solutions. Correcting for the contribution to theuv absorbance by the preservative is sometimes necessary and can be achieved by measuring the absorbance at two wavelengths. The determination of chlorhexidine, as an example of a basic drug withuv absorbing properties which prevent direct measurements of the solution of the cream samples, could be achieved after removal of the interfering compounds by a simple liquid-liquid extraction.     

Analysis of creams

The possibilities of the gas-liquid chromatographic analysis with flame ionization detection of creams of the o/w emulsion type were investigated. Interferences by cream base components in the determination of the active compounds were studied. It appeared to be possible to determine active compounds with a retention index lower than 1900 onov-17 (e.g. methyl salicylate, menthol, thymol, camphor) without clean-up of the cream samples; for the determination of compounds with retention indices between 1900 and 3700, a simple clean-up step suffices.The possible analysis of some of the cream base components together with the active compounds of the creams was investigated as well. Cetomacrogol emulsifying wax, lanette wax sx and cetiol v could be determined easily, whether or not a sample clean-up step was incorporated.     

Analysis of creams

A standard procedure, consisting of twotlc systems, for the qualitative control of creams is presented. All common cream excipients, except those of very high polarity, are separated in a simple gradient elution system, using diethyl ether as the eluent in a chromatographic chamber saturated withn-pentane. The very polar cream base components are separated usingn-butanol-glacial acetic acid-water (20+2+5) as the eluent. The chromatographic behaviour of common cream excipients as well as threefna cream bases and four commercial cream bases is discussed.     

Enzymatic O-methylation of catechols and catecholamines

The reactivity of a number of catechols and catecholamines with regard to the enzymaticO-methylation by catechol-O-methyltransferase (comt) was studied. The reaction was carried out in a vial at a temperature of 37°C, the vial contained a certain concentration of one catechol(amine), catechol-O-methyltransferase (the enzyme),S-adenosylmethionine (the methyldonor), MgCl₂ (a cofactor) and buffer pH=7.85. After certain time intervals samples were taken, the reaction was stopped in acid. The catechol(amine) concentration decrease and the product concentration increase were determined by injecting the samples directly into anhplc connected with a fluorimeter, giving the opportunity of estimating the mass balance. V_max, K_m, C₃/C₄ ratio (=ratio of 3-O- and 4-O-methylated product formed) and the reaction rate at low substrate (catecholamine) concentration (=V_max.[S]/ K_m) — which appears to be related to log P — are given.It is conjectured that V at low substrate concentration is especially determined by the polarity of the catechol(amine) while V_max is primarily determined by other physico-chemical properties like steric conformation (l-dopavs dl-dopa;l-adrenalinevs dl-adrenaline).     

Self-Assembled Biodegradable Nanoparticles Developed by Direct Dialysis for the Delivery of Paclitaxel

Purpose The main objective of this study was to obtain self-assembled biodegradable nanoparticles by a direct dialysis method for the delivery of anticancer drug. The in vitro cellular particle uptake and cytotoxicity to C6 glioma cell line were investigated. Methods Self-assembled anticancer drugs—paclitaxel-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) and poly(l-lactic acid) (PLA) nanoparticles—were achieved by direct dialysis. The physical and chemical properties of nanoparticles were characterized by various state-of-the-art techniques. The encapsulation efficiency and in vitro release profile were measured by high-performance liquid chromatography. Particle cellular uptake was studied using confocal microscopy, microplate reader, and flow cytometry. In addition, the cytotoxicity of this drug delivery system was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on C6 glioma cell line to predict the possible dose response of paclitaxel-loaded PLGA and PLA nanoparticles. Results PLGA and PLA nanoparticles with or without vitamin E tocopherol polyethylene glycol succinate (TPGS) as an additive were obtained, in which the sustained release of paclitaxel of more than 20 days was achieved. The coumarin6-loaded PLGA and PLA nanoparticles could penetrate the C6 glioma cell membrane and be internalized. The cytotoxicity of paclitaxel-loaded nanoparticles seemed to be higher than that of commercial Taxol? after 3 days incubation when paclitaxel concentrations were 10 and 20 μg/ml. Conclusions Direct dialysis could be employed to achieve paclitaxel-loaded PLGA and PLA nanoparticles, which could be internalized by C6 glioma cells and enhance the cytotoxicity of paclitaxel because of its penetration to the cytoplasm and sustained release property.     

A comparative study of different amphetamines on copulatory behavior and stereotype activity in the female rat

The influence of d- and l-amphetamine, fenfluramine, and p-chloroamphetamine on female copulatory behavior (lordosis response) and the induction of stereotype activity was compared. Lordosis response in the female rat has been shown to be inhibited by increased central nervous serotonergic (5-HT) as well as dopaminergic (DA) activity. A dosedependent inhibitory effect on the estroge- + progesterone-induced lordosis response in ovariectomized rats was demonstrated after treatment with the four amphetamines. In contrast, only d- and l-amphetamine induced a stereotype activity, which is considered to be mediated by DA mechanisms. A decrease in DA receptor activity, achieved by pimozide pretreatment, abolished the effect of d-amphetamine on lordosis behavior, but the effect of l-amphetamine was only slightly diminished and the action of fenfluramine and p-chloroamphetamine was unaffected. On the other hand, both l- and d-amphetamine-induced stereotype activity was prevented by pimozide treatment.The data suggest that the d-amphetamine effect on lordosis behavior is mediated by increased DA receptor activity. Although it induces stereotype activity by increased DA activity, l-amphetamine, like fenflueramine and p-chloroamphetamine, inhibits the lordosis response by some other action presumably related to serotonergic mechanisms.     

Hepatoprotective properties of Morinda pubescens J.E. Smith (Morinda tinctoria Roxb.) fruit extract

The present study evaluated the hepatoprotective properties of Morinda pubescens fruit extract against d-galactosamine (d-GalN)-induced liver injury in rats. The fruit extract of M. pubescens was administrated orally at 200 mg/kg of body weight daily once for 21 days and at 21st day, d-GalN (500 mg/kg of body weight) was injected intraperitoneally in rats, to induce liver damage. In d-GalN administrated rats, significant increase in the levels of serum marker enzymes and lipid peroxidation (LPO) in liver and decreased serum and liver antioxidant levels were observed. Pre-treatment with fruit extract to rats reduced the elevated levels of serum marker enzymes and also improves the levels of fucose, ceruloplasmin, and uric acid. Administration of M. pubescens fruit extract prevented increase of LPO and alteration in iron content in experimental animals, besides, considerably increased the levels of glutathione (GSH) and vitamin E when compared to d-GalN intoxicated animals. The present results suggest that the M. pubescens fruit extract has liver-protective property against d-GalN-induced liver injury in rats, which was further confirmed by histopathological studies. The hepatoprotective potentials of fruits of M. pubescens may be due to the presence of phenols and alkaloids, as analyzed by preliminary phytochemical analysis of fruit extract.     

Stability and degradation of sodium nitroprusside

The primary aim of the investigation was to formulate a stable sodium nitroprusside (Np) injection. However, during the investigation a number of inexplicable phenomena were observed, which led us to examine some degradation processes. Reproducible determination of the concentration OfNp, aquopentacyanoferrate (Apcf) (II) and (III), iron-cyanide or cyanide in degraded solutions appeared to be impossible. For this reason we used the absorbance ratio, ΔE, at 394 nm, the ratio E₃₉₄/E₄₄₀ and the resultant colours to study decomposition. The absorbance at 394 nm increases upon controlled irradiation and is accelerated by irradiation of light of greater intensity. This again is accompanied by a relatively rapid decrease in pH value. The addition of citrate, phosphate and edetate does not produce a significant difference of ΔE. Changes were observed in the ratio E₃₉₄/E₄₄₀ and resultant colours. These differences are probably due to chelate formation or iron ions, which delay the formation of Prussian blue, or produce other modifications of Prussian blue, or retard the conversion ofApcf (II) IntoApcf (III. The influence of irradiation appears to be dependent upon the concentration ofNp. IfNp solutions are stored protected from light, no changes are detected in either the spectra or the colour. The longer TheNp solution is irradiated, the more changes occur after storage in the dark. This means that in the presence of degradation products, reaction of these products can continue. Autoclaving of aNp solution for long periods results in a change of spectrum and the pH value. Addition of 0.05% citric acid has a favourable effect on these changes. Sterilisation by autoclaving at 120°C for a 20 minute period is justifiable with the addition of citric acid, provided that the solution is prepared under exclusion of light and air. To obtain an impression of the way in WhichNp degrades, the individual reaction products were also irradiated in the presence and absence of additives. From these results a degradation scheme ofNp upon irradiation was produced.     

Het identificeren van benzodiazepinen en het aantonen van ontledings-produkten met behulp van een en hetzelfde DLC-systeem

Samenvatting Een systeem voor dunnelaagchromatografie wordt beschreven met behulp waarvan twaalf verschillende benzodiazepinen kunnen worden geïdentificeerd en waarmee tevens eventuele ontledingsprodukten kunnen worden aangetoond. Er wordt gebruik gemaakt vanhptlc Silica Gel 60 F₂₅₄ plaatjes en als loopvloeistof wordt tolueen-methanol (96 + 6) gebruikt.De vlekjes kunnen direct onderuv-licht worden waargenomen; ze kunnen nader worden geïdentificeerd na bespuiten met zwavelzuur en/of het reagens van Bratton Marshall. Van enkele benzodiazepinen kan de identiteit echter pas worden vastgesteld nadat ze zijn gehydrolyseerd.     

Discriminative stimulus and reinforcing effects of <Emphasis Type="Italic">p</Emphasis>-fluoro-<Emphasis Type="SmallCaps">l</Emphasis>-deprenyl in monkeys

Rationale para-Fluoro-l-deprenyl (Fludepryl), a halogenated derivative of l-deprenyl, shares structural similarities with amphetamine and may have potential as a medication for psychostimulant abuse. Objectives p-Fluoro-l-deprenyl was evaluated for psychomotor stimulant, discriminative stimulus, and reinforcing effects in squirrel monkeys. Methods One group of monkeys was trained under a ten-response fixed-ratio (FR10) schedule of stimulus termination to discriminate between methamphetamine (0.32 mg/kg, i.m.) and saline. Other monkeys were trained to self-administer i.v. cocaine under either a simple FR10 schedule or a second-order fixed-interval 5-min schedule with FR10 components. Results Full generalization to the methamphetamine-training stimulus was produced by an i.m. dose of 10.0 mg/kg p-fluoro-l-deprenyl. l-Deprenyl and the metabolites of p-fluoro-l-deprenyl, p-fluoro-l-amphetamine, and p-fluoro-l-methylamphetamine were more potent, producing full generalization at doses of 1.0–3.2 mg/kg. Under the FR10 schedule of drug injection, persistent self-administration behavior was maintained by i.v. cocaine injections but not by injections of vehicle or injection doses of p-fluoro-l-deprenyl up to 1.0 mg/kg. However, p-fluoro-l-deprenyl did maintain moderate levels of i.v. self-administration responding under the second-order schedule of drug injection. Peak response rates maintained by 0.1-mg/kg injections of p-fluoro-l-deprenyl were significantly greater than those associated with saline substitution, yet significantly lower than those maintained by cocaine or d-amphetamine. Conclusions p-Fluoro-l-deprenyl has methamphetamine-like discriminative-stimulus properties in squirrel monkeys that appear at higher doses than for its parent compound, l-deprenyl. It also appears to function as a relatively limited reinforcer of intravenous self-administration behavior in monkeys trained to self-administer i.v. cocaine.     

Differences between (+)- and (−)-amphetamine in effects on locomotor activity and l-dopa potentiating action in mice

Summary The l-Dopa-potentiating effects of the two optical isomers of amphetamine, as well as the effects of their own, were investigated in mice, using locomotor activity as test parameter. The study was performed in three steps. First, the time-course were studied for the effects of (+)- and (–)-amphetamine and l-Dopa. Second, dose-response relationships were established for the amphetamine enantiomers. Third, the l-Dopa-potentiating effects, of a few, selected doses of the amphetamine isomers were investigated by establishing dose-response curves for l-Dopa with and without the amphetamines. All animals given l-Dopa were pretreated with an inhibitor of extracerebral aromatic amino acid decarboyxlase. (+)-Amphetamine, 0.5–8 mg/kg, caused a dose-dependent stimulation of locomotoractivity, whereas (–)-amphetamine, 1–4 mg/kg, caused a dose-dependent depression. Doses higher than 8 mg/kg of the laevo-isomer caused stimulation of the activity. (+)-Amphetamine, 0.25 mg/kg, and (–)-amphetamine, 0.5 mg/kg, i.e. doses without any effect on locomotor activity of their own, caused virtually the same shift to the left of the dose-response curve for l-Dopa. (–)-Amphetamine, 4 mg/kg which per se caused depression of locomotor activity, caused a marked potentiation of the l-Dopa-induced stimulation of motor activity. Thus, there does not exist a close correlation between the l-Dopa-potentiating action of the amphetamines and their stimulating properties per se.     

A ligand-based approach for enhancing the pharmacokinetic profile of highly charged antibacterial agents

Glutamate racemase catalyses the interconversion of l-glutamate and d-glutamate making available d-glutamate which is essential for peptidoglycan biosynthesis. Inhibitors of this enzyme have exhibited antibacterial activity with the d-glutamate-analogues group of inhibitors being the most significant as it is the only group that has demonstrated efficacy in a murine thigh Streptococcus pneumoniae infection model. This group of inhibitors, however, showed a narrow antibacterial spectrum that could be due to poor lipophilicity and permeability properties. Here, we have adopted a computational ligand-based drug design approach to enhance the lipophilicity and, hence, the antibacterial spectrum of this group of inhibitors. By limiting the charged groups on our pharmacophore model and identifying key interactions for glutamate racemase binding and inhibition, we have successfully searched a compound database for compounds with both antibacterial activity and increased lipophilicity. However, our compounds appear less potent, likely due to decreased specificity. We also demonstrate that permeability and lipophilicity alone are not responsible for the narrow antibacterial spectrum observed in the d-glutamate analogue inhibitors.     

Anti-aging efficacy of topical formulations containing niosomes entrapped with rice bran bioactive compounds

Context: Rice [Oryza sativa L. (Gramineae)] bran is a rich source of phytochemicals. Its oil also contains several bioactive components that exhibit antioxidative properties such as ferulic acid (F), γ-oryzanol (O), and phytic acid (P) which can be a new source of cosmetic raw materials.

Objective: To evaluate the anti-aging effects of the gel and cream containing niosomes entrapped with the rice bran bioactive compounds.

Materials and methods: The semi-purified rice bran extracts containing F, O, and P which indicated the growth stimulation of human fibroblasts and the inhibition of MMP-2 by sulforhodamine B and gelatin zymography, respectively, were entrapped in niosomes by supercritical carbon dioxide fluid (scCO₂) and incorporated in gel and cream formulations. The skin hydration, elasticity, thickness and roughness, and pigmentation in human volunteers after treated with these gel and creams were investigated by corneometer, cutometer, visiometer, and mexameter, respectively.

Results: Gel and cream containing the semi-purified rice bran extracts entrapped in niosomes gave no sign of erythema and edema detected within 72?h on the shaved rabbit skin by the closed patch test investigated by mexameter and visual observation, respectively. These formulations also demonstrated higher hydration enhancement and improvement of skin lightening, thickness, roughness, and elasticity on the skin of 30 human volunteers within the 28–day treatment not more than 9, 27, 7, 3, and 3 times, respectively.

Discussion and conclusions: The formulations containing niosomes entrapped with the rice bran bioactive compounds gave superior clinical anti-aging activity which can be applied as a novel skin product.     

Comparison of oral ivermectin versus crotamiton 10% cream in the treatment of scabies

Objective: Scabies is a relatively contagious infection caused by a tiny mite (Sarcoptes scabiei). Products used to treat scabies are called scabicides because they kill scabies mites; some also kill mite eggs. The aim of this study was to compare the efficacy and safety of oral ivermectin versus crotamiton 10% cream for the treatment of scabies.

Methods: In total, 320 patients with scabies were enrolled, and were randomized into two groups: the first group received a single dose of oral ivermectin 200?µg/kg body weight, and the second group were treated with crotamiton 10% cream and were told to apply this twice daily for five consecutive days. Treatment was evaluated at intervals of two and four weeks, and if there was treatment failure at the two-week follow-up, the treatment was repeated.

Results: A single dose of ivermectin provided a cure rate of 62.5% at the two-week follow-up, which increased to 87.5% at the four-week follow-up after repeating the treatment. Treatment with crotamiton 10% cream was effective in 46.8% of patients at the two-week follow-up, which increased to 62.5% at the four-week follow-up after this treatment was repeated.

Conclusion: A single dose of ivermectin was as effective as one application of crotamiton 10% cream at the two-week follow-up. After repeat treatment, ivermectin was superior to crotamiton 10% cream at the four-week follow up. The delay in clinical response with ivermectin suggests that it may not be effective against all the stages in the life cycle of the parasite.     

Oorspronkelijke Artikelen

Conclusion Physicochemical theories on the stability of particles against agglomeration, the behaviour of particles at the interface and dissolution appeared to act as powerful tools in predicting the rate controlling steps in the model system used. For such a prediction only basic physicochemical properties of the system involved, which are available in the literature or can easily be measured, have to be known. In the present study not only the primary particle size, but also the agglomeration behaviour and therefore the concentration were important factors, particularly when transport to the interface was the rate-limiting step. But, the initial release rate became independent of particle size and concentration when dissolution at the interface limited the rate. Additives present in low concentrations had a decisive influence on the behaviour of the particles in the suspension and at the interface, and thus on the dissolution rate. The relevance of this model study for the design and development of rectal dosage forms is that an insight has been gained into the basic mechanisms involved in the release of solid substances from an apolar medium. Extrapolation of the results to the in vivo release is speculative, because as stated in the introduction, thein vivo release process was studied only in part and under conditions in many ways different from thein vivo situation. Investigations are in progress to study the spreading of suppositories in vivo and to establish the exact conditions in the rectum after administration of a suppository in order to be able to improve thein vitro simulation of thein vivo situation.

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Autoreferaat van het gelijknamige proefschrift, Leiden 26 juni 1979. Promotor: Prof. Dr. C. J.de Blaey, co-promotor: Prof. J.Polderman; co-referenten Dr. N. A.Armstrong, Prof. Dr. Ir. C. F.Lerk en Dr. P. H.Wiersema.     

The Influence of Water on Electrostatic Charge Retention and Dissipation in Pharmaceutical Compacts for Powder Coating

Purpose. The electrostatic properties of five materials commonly used in tabletting were investigated to assess their suitability for the novel technique of powder coating of pharmaceutical compacts. Methods. Powder resistivity and compact voltage decay properties were determined under dry and wet conditions using purpose built equipment. Results. The organic materials acted as insulators having resistivities >10¹³ m whilst dibasic calcium phosphate showed dielectric behaviour. A clear relationship between water content and resistivity was established for all materials. Electrical conduction across powder surfaces was demonstrated as the predominant mechanism by using low concentrations of magnesium stearate. In materials absorbing significant water a bulk mechanism was also present. After charge injection, decay rates were dependent on resistivity with those having the highest values exhibiting the slowest decay. The chemical nature of the materials was unimportant except at extremely high resistivities. Conditioning of the compacts with water reduced resistivities so that decay half-lives <1 s were achieved. Conclusions. The electrical properties of the compact materials have been modified sufficiently to enable them to be considered suitable for powder coating.     

Adenosine receptors mediating inhibitory electrophysiological responses in rat hippocampus are different from receptors mediating cyclic AMP accumulation

Summary Electrophysiological and biochemical techniques were used to characterize adenosine receptors in rat hippocampus. The site which mediates the inhibitory action of adenosine on excitatory synaptic transmission and on spontaneous interictal spiking had properties similar to the adenosine A1 receptor. Thus, the relative order of potency for adenosine analogs was l-PIACHA>NECA> 2CA (l-PIA = N⁶-phenylisopropyladenosine; CHA = N⁶-cyclohexyl-adenosine; NECA = adenosine 5-ethylcarboxamide; 2CA = 2-chloroadenosine), with EC50 values for the most potent analogs between 10–30 nM. The effect of the stable adenosine analog, particularly CHA and l-PIA, was slow in onset and very slowly reversible. This is suggested to be due both to a slow dissociation of these compounds from the receptors but particularly to the slow equilibrium between the concentration of the drug in the medium surrounding the slices and the biophase within the slices. Adenosine analogs bound specifically to membrane preparations of the rat hippocampus with the order of potency ³H-CHA³H-l-PIA>³H-NECA. Eadie-Hofstee plots of the binding data were curvilinear for each ligand, but only for ³H-l-PIA could the existence of two binding sites with different apparent K _d-values (0.27 and 11.8 nM) be confirmed by curve-fitting. The estimated K _d-values for CHA and NECA were 1.5 and 20 nM, respectively. The adenosine analogs also enhanced ³H-cyclic AMP accumulation in ³H-adenine-labelled hippocampal slices. The rank order of potency of adenosine analogs in increasing cyclic AMP (NECA>2CA>l-PIA>CHA) suggests that this effect is mediated by adenosine A2 receptors. The EC50 values for the accumulation of cyclic AMP were 10–1000 × higher than the EC50 values derived from electrophysiological experiments and the K _d-values from measurements of radioligand binding. Thus, on the basis of absolute as well as rank order potencies of drugs, the adenosine analog-induced electrophysiological responses appear to be related to actions at an A1 receptor site. By contrast, the adenosine receptor-mediated increases in cyclic AMP appears to involve an A2 receptor, the functional role of which is not clear.     

Antidepressant-like effect of 7-nitroindazole in the forced swimming test in rats

Rationale: There is some strong evidence about the role of nitric oxide (NO) as an intercellular messenger in central physiological mechanisms. NO is synthesized from l-arginine by nitric oxide synthase (NOS), as a response to activation of N-methyl-d-aspartate (NMDA) receptors by excitatory amino acids. NMDA receptor antagonists also produce antidepressant-like actions in preclinical models. Objective: In the present study, the involvement of NO in the mechanism of depression was investigated. 7-Nitroindazole (7-NI) (15, 30, 60, 90 mg/kg IP), a selective inhibitor of neuronal NOS was examined. Methods: The Porsolt forced swimming test (FST) has been used as a test for screening new antidepressant agents. Results: 7-NI dose-dependently decreased the immobility time in FST, but produced no significant change in locomotor activity in naive rats. Neither l-arginine, nor d-arginine (100 mg/kg) affected the immobility time in the FST or revealed any effect on locomotion. l-Arginine but not d-arginine, given 10 min before 7-NI, reversed the 7-NI-induced effect on immobility time. Conclusion: Our findings suggest that NO might be an important modulator of depression in rats. Received: 3 June 1999 / Final version: 30 September 1999     

A six-month, placebo-controlled trial of d-cycloserine co-administered with conventional antipsychotics in schizophrenia patients

Rationale d-Cycloserine, a partial agonist at the glycine site of the N-methyl-d-aspartate receptor, has demonstrated inconsistent efficacy for negative and cognitive symptoms of schizophrenia. The strongest evidence for efficacy has come from studies using d-cycloserine at a dose of 50 mg/day added to conventional antipsychotics in trials of 8 weeks duration or less.Objective To assess the efficacy for negative symptoms and cognitive impairment of d-cycloserine augmentation of conventional antipsychotics in a 6-month trial.Methods Fifty-five schizophrenia patients with prominent negative symptoms, treated with conventional antipsychotics, were randomly assigned to treatment with d-cycloserine 50 mg/day or placebo for 6 months in a double-blind, parallel group design.Results Twenty-six subjects completed the 6-month trial; drop-out rates did not differ between treatment groups. d-Cycloserine treatment did not differ from placebo treatment on any primary outcome measure at 8 or 24 weeks, including response of negative symptoms and performance on a cognitive battery. Serum d-cycloserine concentrations did not correlate with response of negative symptoms.Conclusion d-Cycloserine did not exhibit therapeutic effects in this trial, possibly reflecting the high drop-out rate, a narrow range of therapeutic serum concentrations, a modest magnitude of therapeutic effect for the selected outcome measures, or loss of efficacy over time. Because d-cycloserine is a partial agonist with relatively low affinity for the glycine site, the magnitude of potential therapeutic effect may be smaller than that achieved by the higher-affinity full agonists, glycine and d-serine.