The TSC used in this study was generated from cigarettes containing Virginia flue-cured tobacco, the type of tobacco typically contained in Canadian cigarettes. This is distinct from the mixed tobacco blends typically found in American cigarettes. Our earlier toxicogenomic examination of TSC from three Canadian cigarette brands containing either Virginia flue-cured or mixed tobacco blends failed to show any appreciable brand-driven differences in gene expression profiles elicited by in vitro exposures. Therefore, we contend that the similarities and difference between MSC and TSC noted in this study can be cautiously extended to other types of tobacco. Nevertheless, it should also be noted that some toxicogenomic studies have shown that cigarette brand can have a significant effect on gene expression signatures elicited by in vitro CSC exposures , and moreover, many aspects of cigarette design and smoking method have been shown to influence the composition and toxicological activity of TSC.Cannabis sativa is popularly known as marijuana and smoking is the commonly used form of this drug. Based on unofficial estimates of drug consumption conducted by the United Nations, it is the most abused drug in the world, with 140 million consumers. Users are young, and exposures occur during their reproductive age. Moreover, among pregnant women, it appears more frequently in self-reported questionnaires of drug use during gestation. Most of the studies on the toxicity of marijuana use during pregnancy have evaluated the neuro-behavioral effects. Epidemiological evidence has shown that marijuana impairs the growth trajectory of the fetus, resulting in low birth weight,greenhouse growing racks intrauterine growth retardation and congenital malformation. Maternal health is also negatively affected; marijuana-using mothers present higher prevalence of dysfunctional and precipitous labor, as well as meconium-stained amniotic fluid. Other potential adverse effects of smoking marijuana during pregnancy are lesser known.
The majority of the toxicological knowledge about the effects of Cannabis sativa on the reproductive tract and fetal development comes from animal studies. In these studies, exposures are done primarily by gavage of marijuana extract orD9 -THC i.p. Regardless of the route of administration , findings of these studies demonstrate increased resorption rate and reduced fetal weight in both mice and rats. None of the studies have reported fetal malformations. Abel et al. reported that pregnant rats exposed to different doses of Cannabis extract throughout gestation presented reductions in weight gain and food consumption. Birth weight was reduced only in those groups exposed during the third week or during the whole gestation. Charlebois and Fried evaluated the effects of pre-gestational and gestational exposure to Cannabis smoke on rats fed low, normal, or high protein diet. They observed that Cannabis exposure lengthened the gestation period and increased the occurrence of stillbirths and litter destruction. When exposure was coupled with a high protein diet, these effects were attenuated. Furthermore, evaluation of the outcomes of the groups exposed both before and during gestation suggested a degree of tolerance to the drug effects. THC and its metabolites are able to cross the placental barrier and reach the fetus. The endocannabinoid system has an important role in reproduction, from the earliest stages of ontogenic development to parturition, including fertilization, embryo implantation, and placentation. The endocannabinoid system is present in different organs where it plays multiple physiological roles. It is composed of the cannabinoid receptors, CB1 and CB2, which are G protein-coupled receptors that are differentially distributed in the organs , and endogenous molecules derived from arachidonic acid: anandamide and 2-arachidonoylglycerol. Marijuana’s D9 -THC can also bind to CB receptors and activate multiple intracellular signal transduction pathways. Studies in humans have many confounding factors that make it difficult for interpretation and establishment of a causal relationship between smoking marijuana and poor gestational outcomes. Furthermore, toxicological studies conducted in animals use intraperitoneal injections or oral gavage of D9 -THC to perform the exposures, which exclude the interaction of compounds present in the smoke that could also contribute to pregnancy disorders, and the doses used are far beyond the dose commonly experienced by humans.
Most of the published reviews have acknowledged that there are several uncertainties on the effects of maternal marijuana use on gestational and fetal outcomes. There is lack of information on biological mechanisms, whether fetal developmental disruptions occur indirectly , directly, or as a combination of both, and alterations in placental function, changes in hormonal balance, on sex-specific effects, effects on organogenesis of the kidney, lungs, spleen, and thymus. These aspects and the spreading legalization of recreational use of Cannabis sativa point out that there is an urgent need of further toxicological studies to better recognize the effects and elucidate the mechanism involved in this association. In the present study, we developed an experimental murine model to study the effects of recreational use of marijuana during pregnancy to mimic human “real world” exposures in terms of dose and use to evaluate the effects on gestational and fetal outcomes.Fetal development was evaluated during pregnancy using ultrasound biomicroscopy. On GD 10.5 and 16.5, morphological evaluation of all pregnant mice was performed, with two fetuses per dam, where the crown-rump length , biparietal diameter, abdominal anteroposterior diameter, abdominal transverse diameter, placental diameter, and placental thickness were assessed. The analyses were performed with the aid of a high-frequency ultrasound imaging system with a 40-MHz transducer by MMV who was blind to the group. The limited time for the animal’s isoflurane sedation and examination duration was set at 30 min. Furthermore, a random sample of the fixed fetuses from each group was selected and the organs were dissected and weighed to verify the fetal development. Fetal-to-placenta weight ratio was calculated as an indicator of fetal–placental dysfunctions. This measure is expected to increase as pregnancy progresses; if abnormally low or high, it could be indicative of poor fetal outcomes.In this study, marijuana smoke inhalation negatively affected the gestational and fetal outcomes in the Balb/C mice model of heavier, although fetal weight was reduced, compared to control group.
This implies that more grams of placental/gram fetal tissue were needed to support development. This effect was marked in males, but with a borderline significance in females; the mechanisms involved need to be investigated, although hypoxia and maternal metabolic changes might be involved. Many mechanisms could underline the compromised fetal development observed in our study. Reduced weight at birth and restricted intrauterine growth are effects commonly associated with exposure to Cannabis sativa during pregnancy ; however, no previous study has reported increased susceptibility of male fetuses to this effect. Two studies found similar results of increased number of male pups per litter of exposed dams. In our study, estimation of the ponderal index for the Cannabis group indicated that fetal growth is restricted at the end of pregnancy. There were some limitations in this study. Our evaluation of the presence of THC–COOH in murine urine is an indicator of exposure and not dose. The small volume of urine that we could sample after the exposures, and the low-dose exposure that we adopted in this study, imposed many difficulties to determinate its quantities in this biological matrix. In the study of Lichtman et al. , mice were exposed, via inhalation, to smoke produced by burning 50, 100, and 200 mg of marijuana, containing 3.4% of D9 -THC, during 5 min. The estimated D9-THC doses were 2.0, 3.5, and 5.6 mg/kg, respectively. Our exposure was conducted in a very similar manner, we burnt 200 mg of marijuana, during 5 min, however our sample contained 10 times lessD9 -THC , which allows us to suggest a dose of exposure equivalent to 0.5 mg/kg. In summary, our results indicate that smoking marijuana during pregnancy even at low doses can be embryotoxic and fetotoxic, increasing implantation failures and compromising fetal development. The intrauterine environment is a determinant for fetal development, and any perturbation that occurs during this critical period of life can predispose individuals to later life diseases. Therefore, more studies are needed to recognize and better understand the impacts of smoking marijuana during pregnancy and its impacts on future health. These aspects and the spreading legalization of recreational use of this drug deserve critical evaluation.Hemp is one of the most productive and useful plants known for a long time,vertical hydroponic garden it’s used exclusively for the production of medicines, in the textile field, and also used for the preparation of the drug. However, the transformation of hemp generates a high proportion of waste.
Consequently, the development of recycling processes for such wastes present a great interest to the researchers, this waste has integrated the field of composite materials as reinforcing element where he has already been used in composite materials with polypropylene, unsaturated polyester and other composites. Reinforced composites with natural fibers have attracted recently more attention in order to take advantage of their low cost, low density, biodegradability and availability, ease of implementation, their high specific modulus, and ability to be recycled, etc. These benefits are of interest for applications in various fields such as daily life , automotive …, which require lightweight materials with high performance, opportunities for retraining, the minimum impact on the environment, and reduce the cost of the material. The most serious concerned problem with natural fibers is its hydrophilic nature because they are composed of lignocellulose, which contains hydroxyl groups. These fibers are therefore incompatible with hydrophobic thermoplastics, such as polyolefin and have low moisture resistance. These characteristics are weak points for the uses of vegetable fibers as polymer reinforcements. It is then necessary to improve them so as to avoid penalizing mechanical properties. Another important factor is the dispersion of the fibers for obtaining high mechanical properties. These problems are the main limitations to the use of such fibers as reinforcement in polymers. Thus the matrix fiber interface makes it possible to predict the physicochemical properties of the composite materials; a force applied directly to the matrix on the surface of a composite, is transferred to the nearest fiber and propagates through the fiber at the interface. Incompatible interface, leads to in homogeneous distribution of the forces which disrupts the mechanical properties of the composites. By cons, a good interface can allow the composite has the ability to withstand stress, even after several fibers are cut because the force can be transferred to non-broken fibers. Several studies have studied the changes cellulose fiber surface properties to enhance their adhesion with a polymer matrix and reduce moisture absorption. It has been shown that an appropriate treatment applied to the fibers may result in compatibility with the polymer matrix, which improves the quality of the composites.
Various methods such as plasma treatment, alkali, heat, graft copolymerization, treatment with silane or with other chemicals have improved the compatibility of the fibers with the matrix. It is therefore essential to know the chemical surface interactions between the different constituents of the composites before performing a mechanical characterization of the whole. The main objective of this paper is to study the effect of hemp fibers treatment on their individual properties and their interfacial properties when are mixed with the polyurethane matrix. the improvement of interfacial properties of hemp fibers with the polyurethane matrix, contribute to increasing the composite material properties, the choice of the hemp fibers and the matrix is due to their thermal characteristics tested in this study, this incorporation allows the manufacture of a biodegradable composite insulation.Fig. 2 shows images obtained on untreated and treated fibers. It can be seen that the untreated fibers have more compounds at the surface. The surface of untreated fibers is covered with fats, waxes or polysaccharides such as the lignin, hemicelluloses or pectins and therefore much rougher. This indicated that hemp fiber structure consists of cellulose microfibrils covered with hemicellulose and lignin. From these micrographs it can be seen that the cellulosic fiber surface was covered by non-cellulosic constitute. The treated fibers have a smaller diameter than the untreated fibers and their surface roughness is reduced due to the partial dissolution of the amorphous portions of the fibers. More the percentage treatment increases the fiber surface becomes depleted of non-cellulosic material. The shows a change in the appearance of the fiber surface which may be due to the formation of silane-coupling agent on the surface of hemp fibers, the fiber surface was completely covered which confirmed the time required to achieve the equilibrium adsorption respected.