Affimer Tagged Cubosomes: Targeting of Carcinoembryonic Antigen Expressing Colorectal Cancer Cells Using In Vitro and In Vivo Models

Nanomedicines, while having been approved for cancer therapy, present many challenges such as low stability, rapid clearance, and nonspecificity leading to off-target toxicity. Cubosomes are porous lyotropic liquid crystalline nanoparticles that have shown great premise as drug delivery vehicles; however, their behavior in vivo is largely underexplored, hindering clinical translation. Here, we have engineered cubosomes based on the space group Im3m that are loaded with copper acetylacetonate as a model drug, and their surfaces are functionalized for the first time with Affimer proteins via copper-free click chemistry to actively target overexpressed carcinoembryonic antigens on LS174T colorectal cancer cells. Unlike nontargeted cubosomes, Affimer tagged cubosomes showed preferential accumulation in cancer cells compared to normal cells not only in vitro (2D monolayer cell culture and 3D spheroid models) but also in vivo in colorectal cancer mouse xenografts, while exhibiting low nonspecific absorption and toxicity in other vital organs. Cancerous spheroids had maximum cell death compared to noncancerous cells upon targeted delivery. Xenografts subjected to targeted drug-loaded cubosomes showed a 5-7-fold higher drug accumulation in the tumor tissue compared to the liver, kidneys, and other vital organs, a significant decrease in tumor growth, and an increased survival rate compared to the nontargeted group. This work encompasses the first thorough preclinical investigation of Affimer targeted cubosomes as a cancer therapeutic.

γ-Hydroxybutyric Acid: Pharmacokinetics, Pharmacodynamics, and Toxicology

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid present endogenously in the brain and used therapeutically for the treatment of narcolepsy, as sodium oxybate, and for alcohol abuse/withdrawal. GHB is better known however as a drug of abuse and is commonly referred to as the "date-rape drug"; current use in popular culture includes recreational "chemsex," due to its properties of euphoria, loss of inhibition, amnesia, and drowsiness. Due to the steep concentration-effect curve for GHB, overdoses occur commonly and symptoms include sedation, respiratory depression, coma, and death. GHB binds to both GHB and GABAB receptors in the brain, with pharmacological/toxicological effects mainly due to GABAB agonist effects. The pharmacokinetics of GHB are complex and include nonlinear absorption, metabolism, tissue uptake, and renal elimination processes. GHB is a substrate for monocarboxylate transporters, including both sodium-dependent transporters (SMCT1, 2; SLC5A8; SLC5A12) and proton-dependent transporters (MCT1-4; SLC16A1, 7, 8, and 3), which represent significant determinants of absorption, renal reabsorption, and brain and tissue uptake. This review will provide current information of the pharmacology, therapeutic effects, and pharmacokinetics/pharmacodynamics of GHB, as well as therapeutic strategies for the treatment of overdoses. Graphical abstract.

New Linear and Star-Shaped Thermogelling Poly([R]-3-hydroxybutyrate) Copolymers

The synthesis of multi-arm poly([R]-3-hydroxybutyrate) (PHB)-based triblock copolymers (poly([R]-3-hydroxybutyrate)-b-poly(N-isopropylacrylamide)-b-[[poly(methyl ether methacrylate)-g-poly(ethylene glycol)]-co-[poly(methacrylate)-g-poly(propylene glycol)]], PHB-b-PNIPAAM-b-(PPEGMEMA-co-PPPGMA), and their subsequent self-assembly into thermo-responsive hydrogels is described. Atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAM) followed by poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and poly(propylene glycol) methacrylate (PPGMA) was achieved from bromoesterified multi-arm PHB macroinitiators. The composition of the resulting copolymers was investigated by (1) H and (13) C J-MOD NMR spectroscopy as well as size-exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The copolymers featuring different architectures and distinct hydrophilic/hydrophobic contents were found to self-assemble into thermo-responsive gels in aqueous solution. Rheological studies indicated that the linear one-arm PHB-based copolymer tend to form a micellar solution, whereas the two- and four-arm PHB-based copolymers afforded gels with enhanced mechanical properties and solid-like behavior. These investigations are the first to correlate the gelation properties to the arm number of a PHB-based copolymer. All copolymers revealed a double thermo-responsive behavior due to the NIPAAM and PPGMA blocks, thus allowing first the copolymer self-assembly at room temperature, and then the delivery of a drug at body temperature (37 °C). The non-significant toxic response of the gels, as assessed by the cell viability of the CCD-112CoN human fibroblast cell line with different concentrations of the triblock copolymers ranging from 0.03 to 1 mg mL(-1) , suggest that these PHB-based thermo-responsive gels are promising candidate biomaterials for drug-delivery applications.

Independent effect of polymeric nanoparticle zeta potential/surface charge, on their cytotoxicity and affinity to cells

OBJECTIVES

Up to now, little research has been focussed on discovering how zeta potential independently affects polymeric nanoparticle (NP) cytotoxicity.

METHODS

Polymeric nanoparticles of gradient zeta potential ranging from -30 mv to +40 mv were fabricated using the same poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBHHx) biopolymer. Interaction forces between nanoparticles and cells were measured by atomic force microscopy (AFM). Cytotoxicity of the nanoparticles to cells was investigated by using MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay.

RESULTS

Four kinds of nanoparticle with similar sizes and gradient zeta potentials, were fabricated. Those with positive surface charges were found to be more toxic than those with negative surface charges. Positively charged nanoparticles or nanoparticles with higher 'like' charges, offered higher interaction force with cells.

CONCLUSION

This work proposes a novel approach for investigating interaction between NPs and cells, and discloses the importance of controlling zeta potential in developing NPs-based formulations in the future.

[Biocompatibility of electrospun poly(3-hydroxybutyrate) and its composites scaffolds for tissue engineering]

Development of biodegradable polymers-based scaffolds for tissue engineering is a promising trend in bioengineering. The electrospun scaffolds from poly(3-hydroxybutyrate) (PHB) were produced using different additives that changed the physical and chemical characteristics of the products. As a result, the construct consisting of interwoven threads of different diameter (0.8-3.4 mm) were obtained, the smallest diameter was observed in the threads from the PHB using tetrabutilammonium iodide (TBAI) and titanium oxide II (TiO2) as additives. Mesenchymal stem cells (MSC) were cultivated on the scaffolds for the biocompatibility evaluation of obtained materials. Cells viability was determined by the XTT assay test. It was shown that the scaffold from the interwoven threads of lowest diameter is most favorable for MSC growth in comparison with the polymer film and scaffolds from the threads of larger diameter. Thus, it was shown that the biocompatibility of electrospun PHB scaffolds depended on their microstructure. The obtained data can be used for development of scaffolds for tissue engineering.

[The resistance of low brainstem tissue to free radical oxidation in rats during periodic breathing following hydroxybutyrate treatment]

We evaluated tissue resistance to free radical oxidation, in pentobarbital-anesthetized mongrel albino male rats during pathologic periodic breathing following hydroxybutyrate (GHBA) administration. It was shown that GHBA modulated pro- and antioxidant status of brain tissue. In the absence of periodic breathing after GHBA, decreases in resistance of brainstem tissue membranes to induction of free radical oxidation were slightly pronounced. Rats with GHBA-induced periodic breathing exhibited increased membrane sensitivity of medullar neurons to induction of free radical oxidation. We suggest that cellular metabolism and/or membrane mechanisms of respiratory rhythm-generating neurons play a role in the pathogenesis of periodic breathing.

Oral 28-day and developmental toxicity studies of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate

(R)-3-Hydroxybutyl (R)-3-hydroxybutyrate (ketone monoester) has been developed as an oral source of ketones, which may be utilized for energy. In a 28-day toxicity study, Crl:WI (Wistar) rats received diets containing, as 30% of the calories, ketone monoester (12 and 15 g/kg body weight/day for male and female rats, respectively). Control groups received either carbohydrate- or fat-based diets. Rats in the test group consumed less feed and gained less weight than control animals; similar findings have been documented in studies of ketogenic diets. Between-group differences were noted in selected hematology, coagulation, and serum chemistry parameters; however, values were within normal physiological ranges and/or were not accompanied by other changes indicative of toxicity. Upon gross and microscopic evaluation, there were no findings associated with the ketone monoester. In a developmental toxicity study, pregnant Crl:WI (Han) rats were administered 2g/kg body weight/day ketone monoester or water (control) via gavage on days 6 through 20 of gestation. No Caesarean-sectioning or litter parameters were affected by the test article. The overall incidence of fetal alterations was higher in the test group; however, there were no specific alterations attributable to the test substance. The results of these studies support the safety of ketone monoester.

[Current knowledge on gamma-hydroxybutyric acid (GHB), gamma-butyrolactone (GBL) and 1 ,4-butanediol (1,4-BD)]

Gamma-hydroxybutyric acid (GHB) is an old anaesthetic drug which was misused in the 80-90's as an anabolic agent (bodybuilding), recreational drug (drunkenness, euphoric, disinhibiting and aphrodisiac effects) and as a date rape drug (disinhibiting, hypnotic and amnesic effects). Its use in the general population is low, and mainly concerns gay population in nightclubs and young people in parties. The intoxications, above all with alcohol combination, can be severe, with coma and breathing depression, or even fatal. Chronic use leads to psychic and physical dependence; withdrawal syndrome can be severe, with agitation and delirium. In 1999, GHB classification as a narcotic resulted in the increased use of GHB prodrugs gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), which were easily commercially available as solvent and cleaning products. Like GHB, they have a narrow window of use, and share similar toxicity. Their increased cases of recreational use and of severe drug intoxication, abuse and dependence, led the French Ministry of Health in 2011 to prohibit their sale and transfer to the public.

Effects of 1,4-butanediol administration on oxidative stress in rat brain: study of the neurotoxicity of gamma-hydroxybutyric acid in vivo

gamma-Hydroxybutyric acid (GHB) is a naturally occurring compound in the central nervous system (CNS) whose tissue concentration are highly increased in the neurometabolic-inherited deficiency of succinic semialdehyde dehydrogenase (SSADH) activity or due to intoxication. SSADH deficiency is biochemically characterized by increased concentrations of GHB in tissues, cerebrospinal fluid, blood and urine of affected patients. Clinical manifestations are variable and include retardation of mental, motor, and language development along with other neurological symptoms, such as hypotonia, ataxia and seizures, whose underlying mechanisms are practically unknown. The precursor of GHB, 1,4-butanediol (1,4-BD) has been used to study the mechanisms of in vivo GHB neurotoxicity. Therefore, in the present work, the effect of acute administration of 20 or 120 mg/Kg 1,4-BD was investigated on various parameters of oxidative stress, such as spontaneous chemiluminescence, thiobarbituric acid-reactive substances (TBA-RS), total antioxidant reactivity (TAR), sulfhydryl and protein carbonyl contents, as well as the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in homogenates from cerebral cortex of 14-day-old Wistar rats. Acute administration of 120 mg/Kg 1,4-BD significantly increased spontaneous chemiluminescence and TBA-RS levels, while TAR measurement was markedly diminished, whereas injection of a lower dose (20 mg/Kg) did not change the parameters examined. Other parameters of oxidative stress evaluated were not affected by administration of 1,4-BD. These results indicate that 1,4-BD induces in vivo oxidative stress by stimulating lipid peroxidation and decreasing the non-enzymatic antioxidant defenses in cerebral cortex of young rats. If these effects also occur in humans, it is possible that they might contribute to the brain damage found in SSADH-deficient patients and possibly in individuals intoxicated by GHB or its prodrugs (gamma-butyrolactone or 1,4-BD).

In vitro genotoxicity tests for polyhydroxybutyrate – A synthetic biomaterial

The aims of this study are to determine the mutagenicity of a locally produced polyhydroxybutyrate (PHB) using Salmonella mutagenicity test and to find out if PHB altered the expression of p53 and c-myc proto-oncogenes and bcl-xl and bcl-xs anti-apoptotic genes in the human fibroblast cell line, MRC-5. Different concentrations of PHB were incubated with special genotypic variants of Salmonella strains (TA1535, TA1537, TA1538, TA98 and TA100) carrying mutations in several genes both with and without metabolic activation (S9) and the test was assessed based on the number of revertant colonies. The average number of revertant colonies per plate treated with PHB was less than double as compared to that of negative control. For the gene expression analyses, fibroblast cell lines were treated with PHB at different concentrations and incubated for 1, 12, 24 and 48 h separately. The total RNA was isolated and analysed for the expression of p53, c-myc, bcl-xl and bcl-xs genes. The PHB did not show over or under expression of the genes studied. The above tests indicate that the locally produced PHB is non-genotoxic and does not alter the expression of the proto-oncogenes and anti-apoptotic genes considered in this study.

In Vitro Biocompatibility of Schwann Cells on Surfaces of Biocompatible Polymeric Electrospun Fibrous and Solution-Cast Film Scaffolds

The in vitro responses of Schwann cells (RT4-D6P2T, a schwannoma cell line derived from a chemically induced rat peripheral neurotumor) on various types of electrospun fibrous scaffolds of some commercially available biocompatible and biodegradable polymers, i.e., poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polycaprolactone (PCL), poly(l-lactic acid) (PLLA), and chitosan (CS), were reported in comparison with those of the cells on corresponding solution-cast film scaffolds as well as on a tissue-culture polystyrene plate (TCPS), used as the positive control. At 24 h after cell seeding, the viability of the attached cells on the various substrates could be ranked as follows: PCL film > TCPS > PCL fibrous > PLLA fibrous > PHBV film > CS fibrous approximately CS film approximately PLLA film > PHB film > PHBV fibrous > PHB fibrous. At day 3 of cell culture, the viability of the proliferated cells on the various substrates could be ranked as follows: TCPS > PHBV film > PLLA film > PCL film > PLLA fibrous > PHB film approximately PCL fibrous > CS fibrous > CS film > PHB fibrous > PHBV fibrous. At approximately 8 h after cell seeding, the cells on the flat surfaces of all of the film scaffolds and that of the PCL nanofibrous scaffold appeared in their characteristic spindle shape, while those on the surfaces of the PHB, PHBV, and PLLA macrofibrous scaffolds also appeared in their characteristic spindle shape, but with the cells being able to penetrate to the inner side of the scaffolds.

In vitro biocompatibility evaluation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer in fibroblast cells

Among the various biomaterials available for tissue engineering and therapeutic applications, microbial polyhydroxyalkanoates offer the most diverse range of thermal and mechanical properties. In this study, the biocompatibility of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB); containing 50 mol % of 4-hydroxybutyrate] copolymer produced by Delftia acidovorans was evaluated. The cytotoxicity, mode of cell death, and genotoxicity of P(3HB-co-4HB) extract against V79 and L929 fibroblast cells were assessed using MTT assay, acridine orange/propidium iodide staining, and alkaline comet assay, respectively. Our results demonstrate that P(3HB-co-4HB) treated on both cell lines were comparable with clinically-used Polyglactin 910, where more than 60% of viable cells were observed following 72-h treatment at 200 mg/mL. Further morphological investigation on the mode of cell death showed an increase in apoptotic cells in a time-dependent manner in both cell lines. On the other hand, P(3HB-co-4HB) at 200 mg/mL showed no genotoxic effects as determined by alkaline comet assay following 72-h treatment. In conclusion, our study indicated that P(3HB-co-4HB) compounds showed good biocompatibility in fibroblast cells suggesting that it has potential to be used for future medical applications.

Environmental Degradation of Polyester Blends Containing Atactic Poly(3-hydroxybutyrate). Biodegradation in Soil and Ecotoxicological Impact

The degradation of poly[(R,S)-3-hydroxybutyrate], a-PHB, binary blends with natural PHB (n-PHB) and poly(L-lactic acid), PLLA, respectively, has been investigated in soil. In such a natural environment, a-PHB blend component was found to biodegrade. The degradation of a-PHB-containing blends proceeded faster than that of respective plain n-PHB and PLLA. The molecular weight decrease of the n-PHB component was higher, while the same rate of bioerosion of both components was observed for the a-PHB/n-PHB binary blend. For the a-PHB blend with PLLA, the weight loss was accompanied by blend composition changes and the decrease of a-PHB content. However, the PLLA molecular weight decrease was lower in the blend in comparison with the plain PLLA sample. The increase of the number of microorganisms particularly observed for the soil where binary blends were incubated indicates that microbial degradation of a-PHB takes place. The terrestrial plant growth test (cress and barley) demonstrates no environmental toxicity of the materials studied.

[Agitation and gamma-hydroxybutyrate]

Agitation is a symptom in various disorders. Gamma-hydroxybutyrate (GHB) is often abused because of its stimulating effects. Side effects comprise loss of consciousness, coma, and agitated states. We present a 50-year-old patient with repeated GHB intoxications and abstinent alcohol dependency and a video document showing an agitated state. Diagnostic workup is discussed considering the relevant literature on this topic. Intoxication and dependence on GHB are important entities in the contexts of neurology and psychiatry.

A review of evidence leading to the prediction that 1,4-butanediol is not a carcinogen

1,4-Butanediol is an industrial chemical used primarily as an intermediate in the manufacture of other organic chemicals. It has recently been associated with deaths, addiction and withdrawal related to its promotion and use as a dietary supplement. The rapid absorption and conversion of 1,4-butanediol to gamma-hydroxybutyric acid (GHB, or date rape drug) in animals and humans is well documented and is the basis for its abuse potential. A disposition and metabolism study conducted in F344 rats by the National Toxicology Program (NTP) confirmed the rapid conversion of 1-(14)C-1,4-butanediol to (14)CO2. Because of this, the toxicological profile of 1,4-butanediol resembles that of gamma-hydroxybutyric acid. Gamma-hydroxybutyric acid occurs naturally in the brain and peripheral tissues and is converted to succinate and metabolized through the TCA cycle. Although the function of gamma-hydroxybutyric acid in peripheral tissues is not known, the presence of specific high affinity receptors for gamma-hydroxybutyric acid suggests that it functions as a neuromodulator in the brain and neuronal tissue. Gamma-hydroxybutyric acid readily crosses the blood-brain barrier and elicits characteristic neuropharmacologic responses after oral, i.p., or i.v. administration. The same responses are observed after administration of 1,4-butanediol. The cyclic lactone of gamma-hydroxybutyric acid, gamma-butyrolactone, is also rapidly converted to gamma-hydroxybutyric acid by enzymes in the blood and liver in animals and humans, and produces pharmacological effects identical to those produced by 1,4-butanediol and gamma-hydroxybutyric acid. Gamma-butyrolactone was previously evaluated by the NTP in 14-day and 13-week prechronic toxicology studies and in 2-year chronic toxicology and carcinogenesis studies in F344 rats and B6C3F1 mice. No organ specific toxicity occurred. In the carcinogenesis studies there was an equivocal response in male mice based on a marginal increase in the incidence of pheochromocytomas of the adrenal medulla. Because the absence of chronic toxicity and significant carcinogenicity of gamma-hydroxybutyric acid were established in NTP prechronic and chronic studies with gamma-butyrolactone, it is concluded that similar results would be obtained in a 2-year study with 1,4-butanediol, and that 1,4-butanediol is not a carcinogen.

Feasibility ofD-glucuronate to enhance γ-hydroxybutyric acid metabolism during γ-hydroxybutyric acid toxicity: pharmacokinetic and pharmacodynamic studies

Gamma-Hydroxybutyric acid (GHB) is a drug of abuse. Literature studies showed that D-glucuronate acts as an oxidative stimulator of GHB metabolism following in vivo GHB tracer doses. The present proof-of-concept study investigates if D-glucuronate enhances GHB metabolism and inhibits blood-brain barrier (BBB) carrier-mediated transport of GHB for clinically relevant and toxicological concentrations of GHB. In a randomized cross-over study with a 3 day washout period, rats were intravenously administered GHB (200, 400 or 800 mg/kg) with either saline or D-glucuronate (830 mg/kg i.v. bolus followed by a constant infusion of 1.39 g/kg-h). Systemic and renal GHB pharmacokinetics, as well as onset, offset and duration of GHB sedative/hypnotic effects were measured following each GHB dose. In situ brain perfusion was used to determine if D-glucuronate inhibited GHB BBB transport. D-Glucuronate did not alter GHB sedative/hypnotic effects at all three GHB doses. A model independent approach revealed that GHB systemic (AUC, CL(Total), CL(Metabolism), V(SS), T(1/2)) and renal (CL(Renal), f(e)) pharmacokinetic parameters were unaltered by D-glucuronate administration. GHB influx clearance was unaltered by D-glucuronate suggesting a lack of transport inhibition. These observations suggest that although previously shown to be promising at GHB tracer doses, D-glucuronate lacks therapeutic benefit in the treatment of GHB toxicity.

Gamma-hydroxy butyric acid: Neurotransmitter, sedative and party drug

Gamma-hydroxybutyric acid (GHB) as a natural component of the mammalian brain was first introduced in clinical anaesthesic practice more than 40 years ago. The drug was nearly forced from clinical practice because of its prolonged and variable duration of action. The results of recent clinical studies indicate a re-evaluation of GHB in various clinical fields. In the intensive care unit, GHB may be a favourable alternative to established drugs. The results of various clinical studies also suggest that GHB is efficacious in the treatment of alcohol withdrawal syndrome, and narcolepsy. GHB has been used successfully for short-term sedation in children. In addition, GHB has emerged as a street drug ("liquid ecstasy"). Overdose may lead to respiratory depression, coma, and even death. Chronic abuse itself may lead to severe withdrawal syndrome. The purpose of this article is to outline the neurophysiological, pharmacodynamic and pharmacokinetic characteristics of GHB, and to summarize the potential fields of use and misuse of GHB in clinical medicine and toxicology.

Evaluation of γ-Hydroxybutyric Acid for Genotoxicity in the Mouse Micronucleus Assay

Gamma-hydroxybutyric acid (GHB) is an endogenous compound found in the brain and other tissues of mammals. Neurotransmitter/neuromodulator functions have been ascribed to GHB, which has lately become a drug of abuse. In this study, we tested GHB for genotoxicity by measuring its ability to induce micronuclei in polychromatic erythrocytes (reticulocytes) in the peripheral blood of mice. Intraperitoneal injection with a dose of 25 mg/kg/day for 3 days or 50 mg/kg/day x 3 days resulted in a significant (by Dunnett's test) increase of 1.9- to 2.1-fold in micronuclei. However, because increases were small and because no consistent dose-dependent increase in induced micronuclear frequency could be demonstrated, our results do not conclusively show that GHB is an in vivo genotoxicant in mammals.

Biocompatibility test of polyhydroxybutyrate on human cell line

The human fibroblast MRC-5 cells incubated with PHB granules (TM) added at a final concentration of 4 mg/ml showed a time-course pattern of survival. The percentages of dead cells obtained were at the rate of 3.8% after 7 days, respectively. When the MRC-5 cells grown in different material, using the test concentration of 4 mg/ml PCM, they were found to show a similar time-course increasing pattern of death as that obtained with PHB. However, the death was noted in the cells incubated for 7 days, the death rates obtained was 40.54% respectively.

In vitro cytotoxicity evaluation of biomaterials on human osteoblast cells CRL-1543; hydroxyapatite, natural coral and polyhydroxybutarate

The aim of this study was to evaluate the in vitro cytotoxicity of biomaterials; Hydroxyapatite (HA), Natural coral (NC) and Polyhydroxybutarate (PHB). Three different materials used in this study; HA (Ca10(PO4)6(OH)2), NC (CaCO3) and PHB (Polymer) were locally produced by the groups of researcher from Universiti Sains Malaysia. The materials were separately extracted in the complete culture medium (100mg/ml) for 72h and introduced to the osteoblast cells CRL-1543. The viability of osteoblast CRL-1543 cultivated with these extraction materials after 72h incubation period was compared to negative control with neutral red assay by using spectrophotometer at 540nm. The results showed the non-cytotoxicity of the materials. After 72h of incubation period, HA showed 123% viable cells, NC was 99.43% and PHB was 176.75%. In this study, cytotoxicity test dealt mainly with the substances that leached out from the biomaterial. The results obtained showed that the materials were not toxic and also promoted cells growth in the sense of biofunctionality.

Pathway-specific action of gamma-hydroxybutyric acid in sensory thalamus and its relevance to absence seizures

The systemic injection of gamma-hydroxybutyric acid (GHB) elicits spike and wave discharges (SWDs), the EEG hallmark of absence seizures, and represents a well established, widely used pharmacological model of this nonconvulsive epilepsy. Despite this experimental use of GHB, as well as its therapeutic use in narcolepsy and its increasing abuse, however, the precise cellular mechanisms underlying the different pharmacological actions of this drug are still unclear. Because sensory thalamic nuclei play a key role in the generation of SWDs and sleep rhythms, and because direct injection of GHB in the ventrobasal (VB) thalamus elicits SWDs, we investigated GHB effects on corticothalamic EPSCs and GABAergic IPSCs in VB thalamocortical (TC) neurons. GHB (250 microm-10 mm) reversibly decreased the amplitude of electrically evoked EPSCs and GABAA IPSCs via activation of GABAB receptors; however, approximately 60% of the IPSCs were insensitive to low (250 microm-1.0 mm) GHB concentrations. The putative GHB receptor antagonist NSC 382 applied alone had a number of unspecific effects, whereas it either had no action on, or further increased, the GHB-elicited effects on synaptic currents. Low GHB concentrations (250 microm) were also effective in increasing absence-like intrathalamic oscillations evoked by cortical afferent stimulation. These results indicate that low concentrations of GHB, similar to the brain concentrations that evoke SWDs in vivo, differentially affect excitatory and inhibitory synaptic currents in TC neurons and promote absence-like intrathalamic oscillations. Furthermore, the present data strengthen previous suggestions on the GHB mechanism of sleep promotion and will help focus future studies on the cellular mechanisms underlying its abuse.

[Experimental studies on the poly-hydroxybutyrate membrane modified by gamma-radiation and mixed with calcium sulfate]

The objective of this study was to learn the property of poly-hydroxybutyrate membrane (PHBm) modified by gamma-radiation and mixture of calcium sulfate, and to explore the possibility of using modified PHBm for guided tissue regeneration (GTR). The PHB was treated by 5 KGy gamma-radiation and mixed with 1/10 calcium sulfate. The modified PHB membrane was prepared by solvent-casting techniques. The mechanical properties and molecular weight of the modified PHBm were tested. Degradability of the modified PHBm was analyzed in vitro in a buffer solution of KH2PO4-Na2HPO4. Biodegradability and biocompatibility of the modified PHBm were inspected 1, 2, 3 and 6 months after the embedding of the modified PHBm into dogs. The morphology was analyzed by scanning electron microscopy (SEM) and molecular weight was tested to evaluate the biodegradability of PHBm. Biocompatibility of the modified PHBm was observed through tissue response by light microscopy. The extension strength and the extension strain at fracture of the modified PHBm were 23.8 MPa and 1.0% respectively. The morphologic observation of the modified PHBm at different terms showed that the modified PHBm was biodegraded gradually in vitro and in vivo. The capsule surrounding the modified PHBm was mainly composed of fibrocytes and few lymphocytes. The longer the time elapsed, the thinner the capsule enveloping the modified PHBm grew. The modified PHBm possesses satisfactory mechanical properties and biocompatibility, and it is biodegradable in vitro and in vivo. The modified PHB membrane could be applied as GTR membrane.

[Use of gamma-hydroxybutyric acid (GHB) at rave parties and in date rape in France: myth of reality?]

Since many years gamma-hydroxybutyric acid (GHB) is presented as very popular in rave-parties and for bodybuilders. It seems to be a controversy between media coverage and the results of toxicological analysis done in high-level laboratories. In order to clarify this problem, we compiled the data of 6 laboratories. They used the same analytical method by GC/MS. Depending the laboratory, the limit of detection was 1-2 micrograms/mL and the limit of quantification was 2.5-5 micrograms/mL. Two labs where looking for GHB in each forensic case (100 and 150 cases a year). Others labs performed GHB analysis only on specific request (each 10 cases a year). Mean time between ingestion of GHB and blood/urine sampling was 12-48 h. Mean time between sampling and analysis was much higher (a few hours to a few month. All samples were stored at +4 degrees C. Only 3 cases were considered as positive (blood GHB: 165, 132 and 114 micrograms/mL, urine GHB: 7450 and 436 micrograms/mL) They were admitted in an hospital EU. Interpreting results remains very difficult because GHB is endogenous, present in blood and urine, and its half-life is very short. One has to report only "positive" GHB results when amounts are higher than 5 micrograms/mL in blood and 10 micrograms/mL in urine. Obviously, forensic toxicologists have to play a very important part in diagnosis of GHB intoxications and estimating its frequency. Actually, because the lack of data in France, it is not possible to answer the question asked in the title of this paper.

Toxicokinetics of methyl tert-butyl ether and its metabolites in humans after oral exposure

Methyl tert-butyl ether (MTBE) is widely used as an additive to gasoline, to increase oxygen content and reduce tailpipe emission of pollutants. Widespread human exposure to MTBE may occur due to leakage of gasoline storage tanks and a high stability and mobility of MTBE in ground water. To compare disposition of MTBE after different routes of exposure, its biotransformation was studied in humans after oral administration in water. Human volunteers (3 males and 3 females, identical individuals, exposures were performed 4 weeks apart) were exposed to 5 and 15 mg 13C-MTBE dissolved in 100 ml of water. Urine samples from the volunteers were collected for 96 h after administration in 6-h intervals and blood samples were taken in intervals for 24 h. In urine, MTBE and the MTBE-metabolites tert-butanol (t-butanol), 2-methyl-1,2-propane diol, and 2-hydroxyisobutyrate were quantified, MTBE and t-butanol were determined in blood samples and in exhaled air in a limited study of 3 male volunteers given 15 mg MTBE in 100 ml of water. MTBE blood concentrations were 0.69 +/- 0.25 microM after 15 mg MTBE and 0.10 +/- 0.03 microM after 5 mg MTBE. MTBE was rapidly cleared from blood with terminal half-lives of 3.7 +/- 0.9 h (15 mg MTBE) and 8.1 +/- 3.0 h (5 mg MTBE). The blood concentrations of t-butanol were 1.82 +/- 0.63 microM after 15 mg MTBE and 0.45 +/- 0.13 microM after 5 mg MTBE. Approximately 30% of the MTBE dose was cleared by exhalation as unchanged MTBE and as t-butanol. MTBE exhalation was rapid and maximal MTBE concentrations (100 nmol/l) in exhaled air were achieved within 10-20 min. Clearance of MTBE by exhalation paralleled clearance of MTBE from blood. T-butanol was cleared from blood with half-lives of 8.5 +/- 2.4 h (15 mg MTBE) and 8.1 +/- 1.6 h (5 mg MTBE). In urine samples, 2-hydroxyisobutyrate was recovered as major excretory product, t-butanol and 2-methyl-1,2-propane diol were minor metabolites. Elimination half-lives for the different urinary metabolites of MTBE were between 7.7 and 17.8 h. Approximately 50% of the administered MTBE was recovered in urine of the volunteers after both exposures, another 30% was recovered in exhaled air as unchanged MTBE and t-butanol. The obtained data indicate that MTBE-biotransformation and excretion after oral exposure is similar to inhalation exposure and suggest the absence of a significant first-pass metabolism of MTBE in the liver after oral administration.

[Cytotoxicity and genotoxicity of methyl tert-butyl ether and its metabolite to human leukemia cells]

DNA damage of human leukemia (HL-60) cells caused by methyl tert-butyl ether (MTBE), a new gasoline additive, and its metabolites tert-butyl alcohol (TBA), a-hydroxyisobutyric acid (HIBA) and formaldehyde was determined by single cell gel electrophoresis (SCGE), with release of lactate dehydrogenase as an indicator for evaluating its cytotoxicity. Results showed that MTBE, TBA and HUBA at levels of 1 to 30 mmol/L could cause DNA damage in a dose-dependent pattern. Formaldehyde at level of 5 mumol/L could cause DNA damage, but at a higher level could decrease DNA migration. It suggested that MTBE and its metabolites could have genotoxicity, however, with doses causing genotoxic effects, no cytotoxic effect by MTBE, TBA and HIBA was observed, but formaldehyde presented obvious cytotoxic effect.

Mouse embryos in culture: models for understanding diabetes-induced embryopathies and gene function

Both the metabolic studies on diabetes and the genetic studies using antisense oligodeoxynucleotides clearly demonstrate the importance and usefulness of rodent whole embryo culture. Without this technique, these studies would be impossible and, consequently, our knowledge of both normal and abnormal development would not be as advanced as it is today. The culture system fills a unique niche in studies in the fields of developmental biology and teratology and these sciences would have been less well served without Dr. New's contribution.

Characterization of the cell response of cultured macrophages and fibroblasts to particles of short-chain poly[(R)-3-hydroxybutyric acid]

The known biodegradability of poly[(R)-3-hydroxybutyric acid] (PHB) in certain biological environments had led to its proposed use as a biodegradable, biocompatible polymer. Recently, a new, rapidly biodegradable block copolymer that contains crystalline domains of PHB blocks has been synthesized. During degradation of these polymers, the PHB domains are transformed in a first step into small crystalline particles of short-chain PHB. Therefore, particles of short-chain poly[(R)-3-hydroxybutyric acid] (Mn 2300) (PHB-P), as possible degradation products, are investigated here for their effects on the viability and activation of mouse macrophages (J774), primary rat peritoneal macrophages, and mouse fibroblasts (3T3), and their biodegradation or exocytosis (or both) in these cells. Results obtained in the present study indicate that incubation of macrophages with PHB-P concentrations higher than 10 micrograms/mL were found to cause a significant decrease in the number of attached and viable cells as measured in MTT assay, and significant increase in the production levels of tumor necrosis factor-alpha (TNF-alpha) or nitric oxide (NO). At low concentrations, particles of PHB failed to induce cytotoxic effects or to activate macrophages. In addition, signs of possible biodegradation were seen in macrophages. Fibroblasts showed only limited PHB-P phagocytosis and no signs of any cellular damage or cell activation (production of collagen type I and IV, and fibronectin). Taken collectively, the present data indicate that phagocytosis of PHB-P at high concentrations ( > 10 micrograms/mL) is dose dependent and associated with cell damage in macrophages but not in fibroblasts.

Diabetic teratogenesis. In vitro evidence for a multifactorial etiology with little contribution from glucose per se

To determine the extent to which elevated glucose and 3-hydroxybutyrate (3OHB) concentrations contribute to the embryotoxic properties of diabetic serum, we tested the effects of serum from untreated or acutely insulin-treated diabetic rats on the development of mouse embryos during neurulation in vitro. Male Sprague-Dawley rats (n = 143) with streptozocin-induced diabetes for 1 week received infusions of insulin (n = 105) or saline (n = 38) for up to 120 min. The insulin-infused animals were exsanguinated when serum glucose concentrations fell to between 5.6 and 8.3 mM. Saline-infused animals were exsanguinated after a similar duration of infusion. Serum samples were tested for embryotoxic effects on 3-6 somite mouse embryos cultured in vitro for 24 h. Of embryos cultured in serum from untreated diabetic animals (glucose: 24 +/- 1 mM; 3OHB: 2.0 +/- 0.3 mM), 36% (31 of 87) exhibited gross malformations, mostly of the neural tube. Only 16% (10 of 62) of embryos grown in serum from acutely insulin-treated animals (glucose: 7.4 +/- 0.2 mM; 3OHB: 0.20 +/- 0.06 mM) were malformed. This rate that was less than half the rate caused by exposure to diabetic serum (P < 0.01), but a rate that remained much greater than the rate associated with culture in normal serum (0% in this study; < 2% historically). In vitro addition of glucose to serum from insulin-treated animals to re-establish hyperglycemia in the diabetic range (25 mM) resulted in a 17% (12 of 70) malformation rate, nearly identical to the 16% rate caused by normoglycemic serum from insulin-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery by mouse embryos following teratogenic exposure to ketosis

Previous studies have shown that the ketone body D,L,-beta-hydroxybutyrate was teratogenic to mouse embryos exposed in culture during the period of neurulation. Inhibition of closure of the cranial and caudal neuropores was the most frequently occurring defect and these abnormalities were thought to be the forerunner of anencephaly and spina bifida, respectively. However, additional studies demonstrated that embryos could recover morphologically from these effects if the ketone body was removed from the culture medium and if the recovery period was of sufficient duration. In an attempt to define further the phenomenon responsible for this recovery and to determine the extent of the recovery process, the present study examining the cross-sectional area, cell number, and mitotic index of cranial neuroepithelial cells was conducted in mouse embryos cultured from the early somite stage under one of the following conditions: 1) control medium for 60 h; 2) medium containing 32 mmol/l D,L,-beta-hydroxybutyrate for 24 h followed by culture in control medium for an additional 36 h (recovery group); 3) medium containing 32 mmol/l D,L,-beta-hydroxybutyrate for 60 h (continuously exposed group). The results indicate that although neural tube closure occurred in the recovery group, complete recovery was limited to the ventral regions of the forebrain and that the remainder of the prosencephalon as well as the rhombencephalon failed to undergo complete catch-up growth. Thus, cell numbers in these areas were approximately 70% of control values. Therefore, while the gross anatomical disturbances produced by the ketone body may be compensated for, histological alterations in the affected tissues remain. Ultimately, these data suggest that neurological deficits may be an outcome of ketone body exposure during the early stages of embryogenesis.

Biochemical basis for D,L,-beta-hydroxybutyrate-induced teratogenesis

Previous investigations have demonstrated that a potential mechanism for D,L,-beta-hydroxybutyrate (BOHB)-induced teratogenesis in neurulating mouse embryos (5-6 somite stage) after 24 hours of exposure in vitro is mediated by an inhibition of the pentose phosphate pathway (PPP) (Hunter, et al. '87). Employing conceptuses of an earlier stage (2-3 somite stage), the biochemistry of BOHB-induced abnormalities was examined further by exposing embryos to 32 mM BOHB for 24 hour and comparing results with controls with respect to the rate of metabolism via the PPP, de novo pyrimidine biosynthesis (PB), and BOHB utilization. Moreover, the capability of these BOHB-exposed embryos to recover from such an insult was also assessed by transferring them to fresh control medium and allowing them to grow for an additional 36 hours. Both controls and BOHB-exposed embryos showed a progressive increase in rate of BOHB utilization between days 9 and 11.5 of gestation in vitro. Exposure to ketone body produced a 100% rate of neural tube defects and a 25.2% decrease in total embryonic protein content. In contrast to results obtained at the 5-6 somite stage, no inhibition of the PPP in whole conceptuses, embryos, or visceral yolk sacs was observed in the group exposed to BOHB at the 2-3 somite stage. Furthermore, a 7.5 mM D-ribose supplement, an intermediate in the PPP, was unable to rescue the younger embryos from BOHB-induced abnormalities and growth retardation. On the other hand, BOHB produced a 34.3% decrease in pyrimidine biosynthesis in the 2-3 somite embryos, but not in the visceral yolk sac. In addition, embryos recovered biochemically after being transferred to control medium, demonstrating a 25.5% overshoot in pyrimidine biosynthesis. Therefore, the mechanism of BOHB-induced teratogenesis appears to differ depending on the stage of embryonic development at the time of initial exposure.

Morphological and physiological effects of beta-hydroxybutyrate on rat embryos grown in vitro at different stages

Diabetic women are more likely to give birth to infants with congenital malformations than are nondiabetic women. Rodent embryos have been used as a model for the study of abnormal fetal development associated with maternal diabetes, and some of the metabolic factors which are altered in diabetes, such as raised glucose and ketones, have been shown to cause abnormal development of rodent embryos in vitro. The present work explores further the teratogenicity of beta-hydroxybutyrate to rat embryos. To determine the sensitivities of rat embryos at different stages of their development, rat embryos at 9.5 days of gestation have been cultured in vitro for 24 or 48 h, with or without 4 x 10(-2) M beta-hydroxybutyrate for all or part of the culture period. The embryos have been examined by scanning electron microscopy, and a detailed morphometric analysis of one tissue, the neuroepithelium, has been undertaken. The results confirm that beta-hydroxybutyrate causes abnormal development of rat embryos. The results of experiments in which embryos were exposed to beta-hydroxybutyrate for only part of a 48 h culture show that embryos exposed to beta-hydroxybutyrate for a complete 48 h culture are more severely affected than embryos exposed to beta-hydroxybutyrate for only part of the culture and that embryos are more vulnerable to beta-hydroxybutyrate during the first half of a 48 h culture (equivalent to 9.5 to 10.5 days of gestation) than during the second half of a 48 h culture (10.5 to 11.5 days of gestation). The results of experiments in which embryos were cultured with beta-hydroxybutyrate from 9.5 days of gestation for 24 h (equivalent to 9.5 to 10.5 days of gestation) showed that some effects of beta-hydroxybutyrate are already apparent after 24 hours in culture. Many of the abnormalities produced by beta-hydroxybutyrate can be classified as embryonic retardations rather than malformations--that is, embryos show features characteristic of normal, but younger, embryos. Embryos exposed to beta-hydroxybutyrate for the complete 48 h culture period consume less glucose and produce less lactate than control embryos on a per embryo basis, but not on a per microgram protein basis, suggesting that the reduced metabolism is an effect of beta-hydroxybutyrate-induced developmental delay rather than a cause of it.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence for multifactorial origin of diabetes-induced embryopathies

Serum factors characteristically altered in the diabetic state, e.g., glucose, ketone bodies (beta-hydroxybutyrate), and somatomedin inhibitors, induce dysmorphogenesis with or without growth retardation in rodent embryos in whole-embryo culture. Furthermore, serum from diabetic animals, which contains combinations of altered factors, is teratogenic, thereby implying that the diabetic embryopathy is of a multifactorial origin. However, a detailed investigation with various combinations of factors at known concentrations to test this hypothesis has not been conducted. Therefore, we employed combinations of hyperglycemia (300 and 600 mg/dl; 16.6 and 33.3 mM), hyperketonemia (8 and 16 mM D-beta-hydroxybutyrate), and an 800- to 1000-Mr somatomedin-inhibitor serum fraction (at an amount equal to that found in 0.05 and 0.1 ml of serum from a diabetic rat per deciliter culture medium), which represented doses with low teratogenic potential, to determine if interactions of the factors could occur that would increase the risk of malformations in mouse embryos exposed in whole-embryo culture during gastrulation and neurulation. The results demonstrate that glucose and D-beta-hydroxybutyrate can act synergistically to produce growth retardation and additively to induce malformations. The addition of the somatomedin inhibitor exacerbates the induction of malformations produced by the ketone body and glucose. Thus, the origin of the diabetic embryopathy may be multifactorial, involving several altered maternal factors.

Embryonic catch-up growth after exposure to the ketone body D,L,-beta-hydroxybutyrate in vitro

The capability of rodent embryos to recover in growth and development subsequent to exposure to an insult was investigated employing whole embryo culture. Early somite stage mouse embryos were exposed to 32 mM D,L,-beta-hydroxybutyrate (D,L,-beta OHB) for 24 hr (Period I), and were then transferred and maintained in control medium for an additional 36 hr maximum (Period II). Growth of this recovery group (Group B) was monitored at various time points of Period II and the results were compared with an unexposed control group (Group A) and another continuously-exposed reference group (Group C). At the end of Period I, 100% of D,L,-beta OHB-exposed embryos exhibited neural tube closure defects and were growth retarded. At 36 hr of Period II, cranial and caudal neural tube defects of Group B embryos were reduced to 3-7% and 0%, respectively. These embryos also demonstrated an excess in growth velocity during recovery so that at the end of Period II, total protein content was comparable to control values. In contrast, Group C embryos remained growth retarded and showed a significant increase in cranial and caudal neural tube defects (20 and 75%, respectively). Thus, neurulating mouse embryos were capable of catch-up growth following an embryotoxic exposure to D,L,-beta OHB. The progression of development of total protein values and morphological features such as elimination of neural tube defects was intimately related to the amount of time allowed for recovery. Moreover, an elevation of growth rate over normality, which is characteristic of catch-up growth, was observed.

D-(-)-beta-hydroxybutyrate-induced effects on mouse embryos in vitro

The effects of the "physiologically occurring" D-isomer of beta-hydroxybutyrate (D-BOHB) were evaluated in neurulating mouse embryos by using the technique of whole embryo culture. Following a 24-hour culture period D-BOHB induced malformations and growth retardation in a concentration-dependent manner. At a 48 mM concentration essentially all embryos exhibited neural tube defects, and decreased rates of glucose metabolism by the pentose phosphate pathway (PPP) and Krebs cycle were observed when compared to controls. The relationship between an inhibition of the PPP and induction of malformations by DL-BOHB has been reported, and thereby suggests a similar mechanism may be operating for the D-isomer. In contrast, the effect of the D-isomer on the Krebs cycle may result from a replacement of glucose intermediates by those generated from metabolism of D-BOHB. Concentrations as high as 20 mM D-BOHB have been reported in the serum of uncontrolled diabetic patients, and since ketones rapidly equilibrate across extraembryonic membranes, embryos in vivo may be exposed to concentrations equivalent to those which induced malformations in vitro. However, the incidence of malformations induced by D-BOHB was less than that reported for the DL-racemic mixture at equivalent concentrations, thereby suggesting that the L-isomer is also teratogenic. Therefore, until the presence and concentration of L-BOHB in the serum of diabetics are documented, the assessment of the impact of maternal ketosis on the embryo remains incomplete.

Noradrenergic mechanisms in gamma-hydroxybutyrate-induced seizure activity

The electroencephalographic (EEG) response of 6-hydroxydopamine (6-OHDA)-treated and control rats to gamma-butyrolactone (GBL) the prodrug of gamma-hydroxybutyrate (GHB), was determined. Neonatal treatment with 6-OHDA produced a significant reduction of noradrenaline in cortex and hippocampus while sparing noradrenaline in the hypothalamus. Brain dopamine was unaffected. The electrographic seizure produced by GBL was significantly prolonged and more severe in the 6-OHDA-treated animals. That portion of the hypersynchronous seizure induced by GBL which is pharmacologically sensitive to antipetit mal anticonvulsants, Stage 1, was however shortened in the 6-OHDA-treated animals. Reduction of forebrain noradrenaline seems to have a complex effect on GBL-induced seizure in that it results in a reduction of hypersynchronous EEG activity but in a prolongation of the more severe EEG changes of burst suppression normally seen with higher doses of GBL.

Effects of hyperglycemia and ketone bodies on the in vitro development of early somite rate embryos

The teratogenic effects of diabetes are attributed to the influence of hyperglycemia and hyperketonemia as well as to other metabolic factors. We studied the effects of ketone bodies and glucose on the development of early somite rat embryos (day 10 1/2 of gestation) cultured in vitro. D-glucose was added to normal rat serum in concentrations of 2, 5, and 10 mg/ml. Ketone bodies (acetoacetate and beta-hydroxybutyrate, B-HOB) were individually added to normal or to hyperglycemic sera (total glucose concentrations of 3 mg/ml) in the following concentrations: acetoacetate--5, 10, 20, and 40 micrograms/ml; B-HOB--2, 5, and 8 mg/ml. The higher concentrations of each of the substances induced growth retardation and abnormalities. The growth-retarding and teratogenic effects of a combination of the substances, glucose and B-HOB, glucose and acetoacetate, on the development of 10 1/2 day embryos were greater than when each substance was added separately, even at relatively low doses. The greatest teratogenic effects were observed when low concentrations of all three substances were added simultaneously to the culture medium. These results may have direct relevance to human diabetes since diabetes is characterized by a simultaneous elevation of serum levels of all these substances.

The 1986 McCollum award lecture. Fuel-mediated teratogenesis during early organogenesis: the effects of increased concentrations of glucose, ketones, or somatomedin inhibitor during rat embryo culture

Whole rat embryos were explanted at head-fold, late pre-somite stage (day 9.5 of gestation) and cultured in rat sera varyingly supplemented with glucose (3, 6, 9, or 12 mg/mL), D,L sodium beta-hydroxybutyrate (2, 4, 8, or 16 mM), or both (6 mg/mL D-glucose plus 8 mM beta-hydroxybutyrate). During 48 h culture, increasing glucose alone or beta-hydroxybutyrate alone effected growth retardation and faulty neural and extraneural organogenesis in dose-dependent fashion. Synergistic dysmorphogenic effects occurred when minimally teratogenic concentrations of glucose and beta-hydroxybutyrate were combined. Sera from diabetic animals containing somatomedin inhibitor bioactivity were also able to produce growth retardation and major developmental lesions in presence of amounts of glucose and ketones which of themselves were not teratogenic. Thus, aberrant fuels and fuel-related products can impair growth and organogenesis in early post-implantation embryo. Such fuel-mediated teratogenesis may be multifactorial and include possibilities for synergistic and additive interactions.

Contact dermatitis to Alstroemeria

A study was carried out on 50 workers in a floriculture centre to evaluate the incidence of contact dermatitis to Alstroemeria. 3 subjects gave positive reactions to aqueous and ethanolic extracts of cut flowers, stems and leaves. By column chromatography, the allergen was isolated and its chemical structure identified as 6-tuliposide A by proton magnetic resonance and carbon-13 magnetic resonance. Only 6-tuliposide A was isolated from cut flowers, and this gave positive reactions when patch tested at 0.01%; a-methylene-gamma-butyrolactone at 10(-5) (v/v) was positive in the same 3 subjects. Other lactones (gamma-methylene-gamma-butyrolactone, alantolactone, isoalantolactone) were negative at all concentrations used.

Effects of hyperketonemia on mouse embryonic and fetal glucose metabolism in vitro

The ketone body beta-hydroxybutyrate (B-OHB) has been shown to be teratogenic to early-somite mouse embryos, although the mechanism responsible for these defects has not been determined. In an attempt to define this mechanism, the present study investigated the normal pattern of both glucose and B-OHB utilization in the developing embryo and fetus. Furthermore, the metabolic interaction of these two substrates, i.e., the potential for B-OHB to inhibit glycolysis, was studied. All studies compared early and late embryonic periods of development as well as fetal stages. The results show that the early embryo relies almost exclusively on glycolysis for energy metabolism and suggests that there is an increasing importance of the Krebs cycle with increasing gestational age. Similarly, the early embryo has a low capacity to metabolize B-OHB, whereas later gestational stages display a greater rate of utilization. Finally, there appears to be no inhibition of glycolysis by B-OHB (via so-called "substrate interactions") during early embryonic stages. However, the compound significantly inhibits glycolysis during later embryonic and fetal stages. These studies suggest that the teratogenicity of B-OHB in the early embryo is not due to its effects on modulating glycolysis, although this mechanism may be operating at later periods of gestation.

Effects of beta-hydroxybutyrate on rat embryos grown in culture

In order to investigate further the relationship between maternal diabetes and fetal malformation, rat embryos were grown in vitro in the presence of beta-hydroxybutyrate, one of the ketone bodies produced by diabetics. At 10 mM, beta-hydroxybutyrate produced minor abnormalities and at 20 mM it produced major abnormalities in rat embryos.

[Development of progeny after antenatal exposure to lithium oxybutyrate]

Experiments on rats were made to study the effect of lithium hydroxybutyrate and to compare it with lithium carbonate effect on the development of the progeny after antenatal exposure to the drugs. It was established that the lithium salts under study did not produce any conclusive effect on the postnatal development of young rats. The activating component was discovered to be predominant in the action of lithium hydroxybutyrate, whereas the action of lithium carbonate was marked by the inhibitory component. As regards the effect on the development of the progeny, lithium hydroxybutyrate was less hazardous than lithium carbonate.

[Toxic effect of lithium salts on the pregnant rat and on the prenatal development of the fetus]

A study was made of toxic effect of lithium carbonate and lithium hydroxybutyrate in doses of 160 and 500 mg/kg (1/4 LD50) respectively on pregnant rats and development of fetuses. The doses of both the drugs contained an equal amount of lithium (30 mg/kg). It was established that toxicity of the drugs in pregnancy rises almost two-fold as compared to that seen in non-pregnant animals. At the same time the toxic action of lithium hydroxybutyrate was more powerful than that of lithium carbonate. However, the latter drug was found to have a greater embryotoxicity. Apparently, the differences in toxicity and embryotoxicity of the lithium salts are to a definite measure determined by anionic component of salts.

[Effect of a physical load on the toxicological characteristics of sodium oxybutyrate]

Toxicity of sodium hydroxybutyrate administered for a long time was studied in freely moving animals and in those exposed to intense exercise (daily swimming for 30 min). Hematological, biochemical and morphological analyses demonstrated the drug to be little toxic. Intense exercise did not entail the increased toxicity of sodium hydroxybutyrate. On the contrary, the biochemical parameters (the content of creatinine, protein and protein fractions) altered by exercise returned to normal as a result of a prolonged administration of the drug.