Cytokinin deficiency confers enhanced tolerance to mild, but decreased tolerance to severe salinity stress in in vitro grown potato

Cytokinin (CK) is a plant hormone that plays crucial roles in regulating plant growth and development. CK-deficient plants are widely used as model systems for investigating the numerous physiological roles of CK. Since it was previously shown that transgenic or mutant CK-deficient Arabidopsis and Centaurium plants show superior tolerance to salinity, we examined the tolerance of three CK-deficient potato lines overexpressing the Arabidopsis thaliana CYTOKININ OXIDASE/DEHYDROGENASE2 (AtCKX2) gene to 50 mM, 100 mM, 150 mM, and 200 mM NaCl applied in vitro. Quantification of visible salinity injury, rooting and acclimatization efficiency, shoot growth, water saturation deficit, and chlorophyll content confirmed that the CK-deficient potato plants were more tolerant to low (50 mM) and moderate (100 mM) NaCl concentrations, but exhibited increased sensitivity to severe salinity stress (150 and 200 mM NaCl) compared to non-transformed control plants. These findings were corroborated by the data distribution patterns according to principal component analysis. Quantification of the activity of superoxide dismutases, peroxidases, and catalases revealed an impaired ability of AtCKX2-transgenic lines to upregulate the activity of antioxidant enzymes in response to salinity, which might contribute to the enhanced sensitivity of these potato lines to severe salt stress. Our results add complexity to the existing knowledge on the regulation of salinity tolerance by CK, as we show for the first time that CK-deficient plants can exhibit reduced rather than increased tolerance to severe salt stress.

High-performance liquid chromatography evaluation of lipophilicity and QSRR modeling of a series of dual DNA gyrase and topoisomerase IV inhibitors

Bacterial DNA gyrase and topoisomerase IV control the topological state of DNA during replication and represent important antibacterial drug targets. To be successful as drug candidates, newly synthesized compounds must possess optimal lipophilicity, which enables efficient delivery to the site of action. In this study, retention behavior of twenty-three previously synthesized dual DNA gyrase and topoisomerase IV inhibitors was tested in RP-HPLC system, consisting of C8 column and acetonitrile/phosphate buffer (pH 5.5 and pH 7.4) mobile phase. logD was calculated at both pH values and the best correlation with logD was obtained for retention parameter φ0, indicating that this RP-HPLC system could be used as an alternative to the shake-flask determination of lipophilicity. Subsequent QSRR analysis revealed that intrinsic lipophilicity (logP) and molecular weight (bcutm13) have a positive, while solubility (bcutp3) has a negative influence on this retention parameter.

UHPLC-OrbiTrap MS Characterization of Phenolic Profiles in French Marigold Extracts and Analysis of Their Antifeedant Activity against Colorado Potato Beetle

French marigold is an aromatic plant rich in polyphenolic secondary metabolites, which pesticidal potential was examined in this study. Ultra-high-performance liquid chromatography (UHPLC) connected with OrbiTrap mass spectrometer (MS) identified 113 phenolics and revealed the most detailed phytochemistry of French marigold published so far. Depending on plant material (flowers or leaves) and solvents used for extraction (water, methanol, dichloromethane), the phenolic composition varied. Methanol extract of flowers, with 89 identified phenolics and high antioxidant activity statistically comparable with positive control Trolox, was chosen for testing of antifeedant potential against the 3rd and 4th instars of Colorado potato beetle (CPB). A significant reduction in final body mass of 4th larval stage fed with potato leaves coated with methanol extract of flowers in the concentration of 10 mg/mL was observed (157.67 mg vs. 182.26 mg of controls fed with non-treated leaves). This caused delayed molting since treated larvae reached the maximal mass a day after controls and this delay persisted during the entire larval development. Continuous feeding caused a 25% decline in digestive proteolytic activity of the 4th instar in comparison to controls. The results suggest that French marigold methanol extract of flowers could be proposed as a promising antifeedant for CPB management, with an impact on the reduction in the environmental footprint associated with synthetic pesticide application.

In vitro cultivation of tansy (Tanacetum vulgare L.): a tool for the production of potent pharmaceutical agents

In this study, tansy (Tanacetum vulgare L.) in vitro culture was established from seeds collected from natural populations. The multiplication of plantlets was conducted through shoot tips that exhibited potent apical growth and regeneration capacities on basal medium (BM), without the addition of any plant growth regulators (PGRs). PGRs were also omitted for the establishment and cultivation of tansy root cultures. Both abaxial and adaxial leaf surfaces of in vitro micropropagated plantlets were covered with glandular biseriate trichomes. Histochemical staining showed that glandular secretions were rich in lipid and terpene compounds, confirmed by GC-MS analysis of essential oil (EO). In the total EO, similar portions of oxygenated monoterpenes (38.5% m/m) and oxygenated sesquiterpenes (22.6% m/m) were detected. Chemical profiles of methanol extracts of in vitro cultured tansy shoots and roots varied in quantity and quality from those obtained from wild-growingtansy. HPLC analysis indicated that the methanol extracts of in vitro cultured roots were the richest in 3,5-O-dicaffeoylquinic acid (3,5-O-DCQA), in which the concentration was 6 times higher (10.220 mg/g DW) than that in the extract obtained from roots of wild-growing tansy (1.684 mg/g DW). This result is noticeable in the manner of industrial production of biologically active 3,5-O-DCQA that has been shown to have antioxidant, hepatoprotective, antiviral, antimutagenic, and immunomodulatory activity. Biotechnological interventions on secondary metabolite production taking place in trichomes could further enhance the production of some important tansy metabolites and further investigation will be directed toward the elucidation of the pharmaceutical potential of tansy in vitro obtained metabolites, as mixtures or single moieties.

Transcriptome Profiling of the Potato Exposed to French Marigold Essential Oil with a Special Emphasis on Leaf Starch Metabolism and Defense against Colorado Potato Beetle

Flower strips of French Marigold are commonly used pest repellents in potato fields. However, the effect of French Marigold volatiles on potato metabolism, physiology and induced defense is unknown. Thus, a microarray transcriptome analysis was performed to study the effects of French Marigold essential oil (EO) on laboratory-grown potato. After 8 h of exposure to EO, with gas chromatography/mass spectrometry (GC/MS)-detected terpinolene and limonene as dominant compounds, 2796 transcripts were differentially expressed with fold change >2 compared to expression in controls. A slightly higher number of transcripts had suppressed expression (1493 down- vs. 1303 up-regulated). Since transcripts, annotated to different photosynthesis-related processes, were mostly down-regulated, we selected a set of 10 genes involved in the leaf starch metabolism pathway, and validated microarray patterns using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Except for decreased synthesis and induced decomposition of starch granule in leaves, 8 h long EO exposure slightly elevated the accumulation of sucrose compared to glucose and fructose in subjected potato plants. An in vitro feeding bioassay with Colorado potato beetle showed that EO-induced alternations on transcriptional level and in the sugars’ metabolism caused the enhancement of feeding behavior and overall development of the tested larvae. Results of comprehensive analysis of transcriptional responses in potato exposed to French Marigold EO provide a basis for further elucidation of molecular mechanisms underlying eco-physiological interactions in companion planting cropping systems.

Antagonistic Interaction between Phosphinothricin and Nepeta rtanjensis Essential Oil Affected Ammonium Metabolism and Antioxidant Defense of Arabidopsis Grown In Vitro

Phosphinothricin (PPT) is one of the most widely used herbicides. PTT targets glutamine synthetase (GS) activity in plants, and its phytotoxicity is ascribed to ammonium accumulation and reactive oxygen species bursts, which drives rapid lipid peroxidation of cell membranes. In agricultural fields, PPT is extensively sprayed on plant foliage; however, a portion of the herbicide reaches the soil. According to the present study, PPT absorbed via roots can be phytotoxic to Arabidopsis, inducing more adverse effects in roots than in shoots. Alterations in plant physiology caused by 10 days exposure to herbicide via roots are reflected through growth suppression, reduced chlorophyll content, perturbations in the sugar and organic acid metabolism, modifications in the activities and abundances of GS, catalase, peroxidase, and superoxide dismutase. Antagonistic interaction of Nepeta rtanjensis essential oil (NrEO) and PPT, emphasizes the existence of complex control mechanisms at the transcriptional and posttranslational level, which result in the mitigation of PPT-induced ammonium toxicity and in providing more efficient antioxidant defense of plants. Simultaneous application of the two agents in the field cannot be recommended; however, NrEO might be considered as the PPT post-treatment for reducing harmful effects of herbicide residues in the soil on non-target plants.

Evaluation of tansy essential oil as a potential "green" alternative for gypsy moth control

The development of "green" alternatives to chemical pesticides could play a crucial role in integrated pest management (IPM). Their use is considered either as a substitution for or in addition to hazardous synthetic products. We analysed the influence of three concentrations of tansy (Tanacetum vulgare L.) essential oil (EO), previously characterised by GC-MS, on the survival and moulting of the 2nd instar and the nutritional indices of the 4th instar gypsy moth (Lymantria dispar L.) larvae. In a residual contact toxicity assessment, the exposure to tansy EO caused low mortality (< 10%) while larval development was significantly slowed down, i.e., the percentage of larvae that moulted into the 3rd instar was reduced. On the other hand, when tansy EO was incorporated into the diet (digestive toxicity assay), high mortality and a lack of moulting after 120 h of eating were recorded for the highest applied concentration of EO. During 48 h of feeding on EO-supplemented food at concentrations of 0.5 and 1% (v/v), the relative growth rate (RGR) of the 4th instar larvae significantly decreased, which can be explained by a significant reduction of the relative consumption rate (RCR) and significantly or marginally significantly lower efficiency of conversion of ingested food into insect biomass (ECI). Although the RCR was also reduced with the lowest applied EO concentration (0.1%), the ECI was not affected which meant the RGR was as high as it was for the control larvae. ECI changes, when two higher EO concentrations were applied, were due to a reduction in the efficiency of conversion of digested food into biomass (ECD), while approximate digestibility was unaffected by the presence of EO in the food. Our results on the significant negative effects of tansy EO on gypsy moth larval survival, development time, and nutritional physiology suggest that it could be considered in future designs for botanical insecticides for gypsy moth control.

Beneficial implications of sugar beet proteinase inhibitor BvSTI on plant architecture and salt stress tolerance in Lotus corniculatus L

Food demands of increasing human population dictate intensification of livestock production, however, environmental stresses could jeopardize producers' efforts. Forage legumes suffer from yield losses and poor nutritional status due to salinity increase of agricultural soils. As tools aimed to reduce negative impacts of biotic or abiotic stresses, proteinase inhibitors (PIs) have been promoted for biotechnological improvements. In order to increase tolerance of Lotus corniculatus L. to salt stress, serine PI, BvSTI, was introduced into this legume using Agrobacterium rhizogenes, with final transformation efficiency of 4.57%. PCR, DNA gel-blot, RT-PCR and in-gel protein activity assays confirmed the presence and activity of BvSTI products in transformed lines. Plants from three selected transgenic lines (21, 73 and 109) showed significant alterations in overall phenotypic appearance, corresponding to differences in BvSTI accumulation. Lines 73 and 109 showed up to 7.3-fold higher number of tillers and massive, up to 5.8-fold heavier roots than in nontransformed controls (NTC). Line 21 was phenotypically similar to NTC, accumulated less BvSTI transcripts and did not exhibit an additional band of recombinant trypsin inhibitor as seen in lines 73 and 109. Exposure of the transgenic lines to NaCl revealed different levels of salt stress susceptibility. The NaCl sensitivity index, based on morphological appearance and chlorophyll concentrations showed that lines 73 and 109 were significantly less affected by salinity than NTC or line 21. High level of BvSTI altered morphology and delayed salt stress related senescence, implicating BvSTI gene as a promising tool for salinity tolerance improvement trials in L. corniculatus.

Nepetalactone-rich essential oil mitigates phosphinothricin-induced ammonium toxicity in Arabidopsis thaliana (L.) Heynh

Active ingredient of the commercial herbicide BASTA (B), phosphinothricin, acts as an inhibitor of glutamine synthetase (GS), a key enzyme in ammonium assimilation. The treatment with BASTA leads to an elevation of ammonium levels in plants and further to various physiological alterations, ammonium toxicity and lethality. Results of the present study emphasize the complexity underlying control mechanisms that determine BASTA interaction with essential oil (EO) from Nepeta rtanjensis (NrEO), bioherbicide inducing oxidative stress in target plants. Simultaneous application of NrEO and BASTA, two agents showing differential mode of action, suspends BASTA-induced ammonium toxicity in Arabidopsis thaliana plants. This is achieved through maintaining GS activity, which sustains a sub-toxic and/or sub-lethal ammonium concentration in tissues. As revealed by the present study, regulation of GS activity, as influenced by BASTA and NrEO, occurs at transcriptional, posttranscriptional, and/or posttranslational levels. Two genes encoding cytosolic GS, GLN1;1 and GLN1;3, are highlighted as the main isozymes in Arabidopsis shoots contributing to NrEO-induced overcoming of BASTA-generated ammonium toxicity. The effects of NrEO might be ascribed to its major component nepetalactone, but the contribution of minor EO components should not be neglected. Although of fundamental significance, the results of the present study suggest possible low efficiency of BASTA in plantations of medicinal/aromatic plants such as Nepeta species. Furthermore, these results highlight the possibility of using NrEO as a bioherbicide in BASTA-treated crop fields to mitigate the effect of BASTA residues in contaminated soils.

Hairy root culture as a valuable tool for allelopathic studies in apple

Allelopathic plants exploit their chemical 'weapons' to prevail over the competition, suppress neighboring plants and consequently use the available resources more efficiently. However, the investigation of plant allelopathic interactions in rhizosphere is difficult to perform because of its high complexity due to interactions of biotic and abiotic factors. Thus, autonomous, aseptic root cultures of apple (Malus × domestica Borkh.) could facilitate allelopathic studies. We report on the successful genetic transformation of apple cultivars Melrose, Golden Delicious, Čadel and Gloster using Agrobacterium rhizogenes (Riker et al. 1930) Conn 1942 strain 15834 and for the first time the establishment of apple autonomous and permanent in vitro hairy root cultures that could be used as a new tool for apple allelopathic assays. Molecular characterization of transgenic hairy root lines was conducted to elucidate the possible relationship between expression of T-DNA genes and root growth characteristics that include branching. Similar content of phenolic acids (chlorogenic, caffeic, syringic, p-coumaric and ferulic), glycosilated flavonoids (rutin, quercitrin, isoquercitrin, kaempferol-3-glucoside) and flavonoid aglycones (quercetin and naringenin), and dihydrochalcone phloridzin, was detected in untransformed and transgenic apple root tissue by ultra high-performance liquid chromatography with mass spectrometry (UHPLC/(+/-)HESI-MS/MS) analyses, confirming that genetic transformation did not disturb secondary metabolite production in apple. Chlorogenic and caffeic acids and dihydrochalcones phloridzin and phloretin were detected as putative allelochemicals exuded into the growth medium in which transgenic roots were maintained for 4 weeks. Apple hairy root exudates significantly affected shoot and root development and growth of test plant Arabidopsis thaliana (L.) Heynh. seedlings after 5 or 10 days of treatment. Additionally, core cell-cycle genes CDKA1;1, CDKB2;1, CYCA3;1 and CYCB2;4 were down regulated in Arabidopsis shoots suggesting, in part, their role in inhibition of shoot growth. The present work highlighted an autonomous and permanent in vitro hairy root culture system as a valuable tool for studying allelopathic potential of apple, offering new perspective for allelopathy background elucidation in this important fruit species.

Expression profiles of organogenesis-related genes over the time course of one-step de novo shoot organogenesis from intact seedlings of kohlrabi

Kohlrabi (Brassica oleracea var. gongylodes) is an important vegetable crop that is able to undergo shoot regeneration in culture from intact seedlings in a single-step regeneration process, using cytokinin as the only plant growth regulator. In this work, we present the expression profiles of seven organogenesis-related genes over the time course of shoot regeneration from intact seedlings of kohlrabi cv. Vienna Purple on shoot regeneration media containing trans-zeatin, cis-zeatin, benzyl adenine or thidiazuron. Two auxin transporter genes - PIN3 and PIN4, a cytokinin response regulator - ARR5, two shoot apical meristem-related transcription factors - CUC1 and RGD3, and two cell cycle-related genes - CDKB2;1 and CYCB2;4 - displayed bimodal expression patterns on most cytokinin-containing media when their expression levels were normalized against control plants grown on hormone-free media. The first expression peak corresponded to direct upregulation by cytokinin from the growth media, and the second one reflected transcriptional events related to callus formation and/or acquisition of organogenic competence, corresponding to the shoot regeneration phases that have already been characterized in Arabidopsis thaliana. We demonstrate that the genes involved in the two-step shoot regeneration of Arabidopsis display their expected expression profiles during the single-step shoot regeneration of its close phylogenetic relative kohlrabi confirming the universality of their roles in the distinct phases of the regeneration process in Brassicaceae. The results presented here represent a first step towards genetic characterization of the morphogenetic processes in this important crop species.

Physiological and cell ultrastructure disturbances in wheat seedlings generated by Chenopodium murale hairy root exudate

Chenopodium murale L. is an invasive weed species significantly interfering with wheat crop. However, the complete nature of its allelopathic influence on crops is not yet fully understood. In the present study, the focus is made on establishing the relation between plant morphophysiological changes and oxidative stress, induced by allelopathic extract. Phytotoxic medium of C. murale hairy root clone R5 reduced the germination rate (24% less than control value) of wheat cv. Nataša seeds, as well as seedling growth, diminishing shoot and root length significantly, decreased total chlorophyll content, and induced abnormal root gravitropism. The R5 treatment caused cellular structural abnormalities, reflecting on the root and leaf cell shape and organization. These abnormalities mostly included the increased number of mitochondria and reorganization of the vacuolar compartment, changes in nucleus shape, and chloroplast organization and distribution. The most significant structural changes were observed in cell wall in the form of amoeboid protrusions and folds leading to its irregular shape. These structural alterations were accompanied by an oxidative stress in tissues of treated wheat seedlings, reflected as increased level of H₂O₂ and other ROS molecules, an increase of radical scavenging capacity and total phenolic content. Accordingly, the retardation of wheat seedling growth by C. murale allelochemicals may represent a consequence of complex activity involving both cell structure alteration and physiological processes.

Co-expression of the proteinase inhibitors oryzacystatin I and oryzacystatin II in transgenic potato alters Colorado potato beetle larval development

Colorado potato beetle (CPB; Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae) has shown a remarkable adaptability to a variety of control measures. Although oryzacystatin I and II (OCI and OCII) have potential in controlling pests that use cysteine proteinases for food digestion, expression of a single OC gene in potato exhibited a minimal or no effect on CPB fitness traits. The aim of this study was to examine the effect of coexpressed OCI and OCII in potato (Solanum tuberosum L.) cultivars Desiree, Dragačevka and Jelica on CPB larvae. Growth parameters, consumption rates and food utilization, as well as activity of proteases of CPB larvae were assayed. Second and third instar larvae fed on transformed leaves molted earlier and had higher relative growth and consumption rates than larvae fed on nontransformed leaves, while efficiency of food utilization was unaffected. In contrast, fourth instar maximum weight gain and amount of leaves consumed were about 20% lower for the larvae fed on transgenic potato. Analysis of total protease activity of third instar larvae revealed reduction in overall proteolytic activity measured by azocasein hydrolysis, accompanied with inhibition of cysteine proteinase activity 24 h after ingestion of potato leaves expressing OCI and OCII. However, after long-term feeding on transformed leaves proteolytic activities of larvae became similar to the controls. Although feeding on OCI/OCII leaves did not affect larval survival, coexpression of OC genes reduced the development time and thus significantly decreased plant damage caused by CPB larvae.

Application of biopartitioning micellar chromatography and QSRR modeling for prediction of gastrointestinal absorption and design of novel β-hydroxy-β-arylalkanoic acids

Gastrointestinal absorption of thirteen novel β-hydroxy-β-arylalkanoic acids (HAA) with anti-inflammatory activity was predicted by use of biopartitioning micellar chromatography and compared to ibuprofen. All tested HAA have lower retention factors (k) and lower expected gastrointestinal absorption than ibuprofen, whereas derivatives with the highest values of k are 1C, 2APTF and 2C. Quantitative structure-retention relationship (QSRR) analysis was performed in order to identify molecular descriptors with the highest influence on k and ANN(k) model was selected as optimal. Descriptors which form this model (nBM, P_VSA_LogP_8 and Eta_L) indicate that replacement of phenyl ring with a saturated or partially unsaturated one, as well as presence of halogens and nitro group should positively affect k values. On the basis of these conclusions, six novel HAA were designed and selected QSRR model was used for the prediction of their k values.

Extraordinary Adaptive Plasticity of Colorado Potato Beetle: "Ten-Striped Spearman" in the Era of Biotechnological Warfare

Expanding from remote areas of Mexico to a worldwide scale, the ten-striped insect, the Colorado potato beetle (CPB, Leptinotarsa decemlineata Say), has risen from being an innocuous beetle to a prominent global pest. A diverse life cycle, phenotypic plasticity, adaptation to adverse conditions, and capability to detoxify or tolerate toxins make this insect appear to be virtually “indestructible”. With increasing advances in molecular biology, tools of biotechnological warfare were deployed to combat CPB. In the last three decades, genetically modified potato has created a new challenge for the beetle. After reviewing hundreds of scientific papers dealing with CPB control, it became clear that even biotechnological means of control, if used alone, would not defeat the Colorado potato beetle. This control measure once again appears to be provoking the potato beetle to exhibit its remarkable adaptability. Nonetheless, the potential for adaptation to these techniques has increased our knowledge of this pest and thus opened possibilities for devising more sustainable CPB management programs.

Interaction with gravitropism, reversibility and lateral movements of phototropically stimulated potato shoots

Phototropic (PT) and gravitropic (GT) bending are the two major tropic movements that determine the spatial position of potato shoots. We studied PT bending of potato plantlets grown under long-day photoperiods in several prearranged position setups providing different interactions with the GT response. Starting with the standard PT stimulation setup composed of unilateral irradiation of vertically positioned shoots, experiments were also done in antagonistic and synergistic setups and in treatments with horizontal displacement of the light source. In the standard setup, PT bending suppressed the GT bending, which could occur only if the PT stimulation was cancelled. The antagonistic position, with phototropism and gravitropism attempting to bend shoots in opposite directions, showed phototropism and gravitropism as independent bending events with the outcome varying throughout the day reflecting diurnal changes in the competence of individual tropic components. Whilst gravitropism was constant, phototropism had a marked daily fluctuation of its magnitude with a prominent morning maximum starting an hour after the dawn in the growth room and lasting for the next 6 h. When phototropism and gravitropism were aligned in a synergistic position, stimulating shoot bending in the same direction, there was little quantitative addition of their individual effects. The long period of morning PT bending maximum enabled multiple PT bending events to be conducted in succession, each one preceded by a separate lag phase. Studies of secondary PT events showed that potato plantlets can follow and adjust their shoot position in response to both vertical and horizontal movements of a light source. PT bending was reversible, since the 180° horizontal change of a blue light (BL) source position resulted in reversal of bending direction after a 20-min-long lag phase.

Pest protection conferred by a Beta vulgaris serine proteinase inhibitor gene

Proteinase inhibitors provide a means of engineering plant resistance to insect pests. A Beta vulgaris serine proteinase inhibitor gene (BvSTI) was fused to the constitutive CaMV35S promoter for over-expression in Nicotiana benthamiana plants to study its effect on lepidopteran insect pests. Independently derived BvSTI transgenic tobacco T2 homozygous progeny were shown to have relatively high BvSTI gene transcript levels. BvSTI-specific polyclonal antibodies cross-reacted with the expected 30 kDA recombinant BvSTI protein on Western blots. In gel trypsin inhibitor activity assays revealed a major clear zone that corresponded to the BvSTI proteinase inhibitor that was not detected in the untransformed control plants. BvSTI-transgenic plants were bioassayed for resistance to five lepidopteran insect pests. Spodoptera frugiperda, S. exigua and Manduca sexta larvae fed BvSTI leaves had significant reductions in larval weights as compared to larvae fed on untransformed leaves. In contrast, larval weights increased relative to the controls when Heliothis virescens and Agrotis ipsilon larvae were fed on BvSTI leaves. As the larvae entered the pupal stage, pupal sizes reflected the overall larval weights. Some developmental abnormalities of the pupae and emerging moths were noted. These findings suggest that the sugar beet BvSTI gene may prove useful for effective control of several different lepidopteran insect pests in genetically modified tobacco and other plants. The sugar beet serine proteinase inhibitor may be more effective for insect control because sugar beet is cropped in restricted geographical areas thus limiting the exposure of the insects to sugar beet proteinase inhibitors and build up of non-sensitive midgut proteases.

[Experimental study of the pathogenesis of frostbite. Part III. Significance of energy status of muscle tissue in the pathogenesis of frostbite]

The authors have investigated energy status of muscle tissue of the lower legs of Wistar rats subjected to freezing, as well as the dependence of ultrastructure changes in muscle tissue mitochondria on the intensity of freezing. The animals were divided into three experimental groups: two groups were exposed to cryoinjury of different intensity, while the third was the control one. Cryoinjury was applied over an experimental after thawing were taken samples of muscle tissue for the analysis of content of energy phosphates and carbohydrates' metabolites, respectively, as well as for morphometric analysis of mitochondria volume out of frozen right and unfrozen left lower legs. Results obtained from different experimental groups were compared mutually and with control group that was not exposed to cryoinjury, respectively. It was found that the freezing in muscle tissue caused hydrops degeneration of mitochondria, depletion of energy reserves, reduction of energy status and the activation of mechanism of anaerobic metabolism. All these alterations were proportional to the intensity of freezing and considerably influenced contractility function of muscle cells, causing prolonged spasm of arterioles in thawed tissue, i.e., rigor congelationis that was primarily defined as an important factor in the pathogenesis of ischemic impairment of thawed tissues.

[Experimental study of the pathogenesis of frostbite. Part II. Role of the sympathetic-adrenergic system in tissue reperfusion immediately after thawing]

The authors have investigated the role of sympathetic-adrenergic system in reperfusion of muscular tissue of the feet of Wistar rats immediately after thawing using alpha adrenergic blocker phentolamine methanesulfonate (Regitin). Cryoinjury was applied over an experimental model of local, controlled freezing of different intensity for certain experimental groups. Blood flow through microcirculation was measured by scintigraphy, following Tc-99m-pertechnetate clearance that was given in muscular mass of frozen right, as well as unfrozen left feet of rats. Results obtained in some experimental groups were compared mutually, as well as with the control group that was not exposed to cryoinjury. The investigations have revealed that immediately after thawing existed significant reduction, non-dependent of the intensity of freezing, in blood flow in microcirculation of both frozen and unfrozen feet of rats compared to the control group. Significant increase of microcirculatory blood flow in unfrozen feet was caused by blockade of sympathetic-adrenergic system, while the blood flow remained unchanged in the frozen ones. The reduction of blood flow in microcirculation of frozen tissues immediately after thawing was not associated with sympathetic-adrenergic factor.

Inhibition of leukotriene formation by diethylcarbamazine modifies the acid-base balance in the rabbits with blast injuries of the lungs

Our previous investigations have shown that leukotrienes are important mediators/modulators in local response of the lungs to the blast injury. The aim of the present study was to investigate the effects of diethylcarbamazine (DEC), an 5-lipoxygenase inhibitor, on the acid-base balance following pulmonary blast injury. The experiments were performed on rabbits (n = 16) subjected to focused blast over-pressure on the middle thoracic region. Immediately prior to blast injury one group was treated with DEC (50 mg/kg, i.v.), and the other with the same volume of saline. Parameters of acid-base balance were measured in arterial and venous blood before and 30 minutes after injury. Obtained results indicated that DEC treatment reduced some disturbances induced by blast injury (prevents edema formation in the lungs, permits respiratory compensation of metabolic acidosis in general circulation, normalization of respirations and slightly improves the oxygen saturation of hemoglobin), in spite of intensified hemodynamic insufficiencies associated with increased hypotension and acidosis in the peripheral circulation.

The cardiovascular effects of the administration of L-NAME during the early posthemorrhagic period

1. The effects of the various doses of NG-nitro-L-arginine methyl ester (L-NAME, 10 and 30 mg/kg) on some cardiovascular and biochemical parameters during the early posthemorrhagic period were studied in anesthetized rabbits subjected to hemorrhagic hypovolemia. 2. Hemorrhagic shock was produced by intermittent bleeding of 40% of the estimated blood volume for 15 min. Blood samples were taken before and after bleeding (0, 15 and 60 min). Simultaneously, the mean arterial pressure (MAP) and the heart rate (HR) were measured. Hemorrhaged rabbits were treated by L-NAME10 or L-NAME30 (10 or 30 mg/kg, i.v. bolus injection, respectively) or the corresponding volumes of saline (0.6 ml, i.v. bolus) immediately after the end of bleeding. 3. The observed cardiovascular parameters (MAP, HR) were significantly reduced after the end of bleeding in all rabbits. 4. The rise of the MAP was significantly more pronounced 30 min after the injection of L-NAME30 in comparison with the corresponding values in the saline (S) group. In contrast, L-NAME10 produced only a small, insignificant increase in the MAP in hemorrhaged rabbits. 5. The L-NAME30-induced rise of the MAP was accompanied by a severe bradycardia, hyperkalemia and an aggravated metabolic acidosis, more severe than the corresponding disturbance of the acid-base status in the S group. The changes in the acid-base parameters were observed both in arterial (pH, excess base) and in venous blood (pH) of hemorrhaged rabbits. 6. In conclusion, the i.v. bolus injection of L-NAME30 (immediately after the end of bleeding) produced a significant increase in the MAP during the first hour after the injury, but the presumable inhibition of the endothelial constitutive nitric oxide synthase during the early posthemorrhagic period resulted in severe cardiovascular and metabolic disturbances.

Early plasma amino acid pool alterations in patients with military gunshot/missile wounds

Plasma amino acid profiles in patients during the early period (first 18 hours) following military gunshot/missile wounds were investigated. Patients (n = 29) were casualties from the war in the former Yugoslavia with injury severity scores ranging from 4 to 18. They were divided into three groups: soft tissue (muscle) damage, wounds with fractures, and vital structures injured. Controls were normal blood donors (n = 17). Free amino acids were analyzed in venous plasma. Increased concentrations of phenylalanine and glutamine associated with increased molar phenylalanine/tyrosine ratio in plasma indicated increased net protein catabolism in the peripheral tissues, regardless of the type of injured tissues. Decreased plasma arginine, ornithine and citrulline levels, accompanied with increased molar glutamine/valine ratio, suggested disturbance in urea cycle activity, although urea level was not altered. We concluded that early changes in plasma amino acid pool characteristics after wounds were of systemic origin, not related to the type of injured tissues.

Glucose as an adjunct triage tool to the Red Cross Wound Classification

The plasma concentrations of glucose, adrenaline, noradrenaline, insulin, and cortisol were measured in 59 patients within 18 hours of military gunshot/missile (MG/M) wound. The wounds were categorized by the Red Cross Wound Classification (RCWC) and assessed by the Injury Severity Score (ISS) method. The majority of the measured biochemical parameters, except insulin, were significantly increased after MG/M wounds, compared with control values. Plasma glucose concentration in wounded patients was positively related to ISS over the whole severity range. Plasma insulin concentration increased with glucose. Noradrenaline and cortisol were positively related to glucose. Because hemorrhage is the most common cause of general response to MG/M wound, we concluded that glucose measurement could be a useful adjunct tool to the RCWC in rapid and accurate assessment of severely wounded patients, especially those with occult thoraco-abdominal wounds.

Ionizing radiation-induced expression of the genes associated with the acute response to injury in the rat

Total-body irradiation of rats with doses ranging from an LD10/30 to an LD100/30 induced a dose-dependent increase in the concentration of serum protein associated with the acute response to the irradiation. However, this increase was reached at a later time and was not as pronounced as described previously during the typical acute phase of the response found experimentally (A. Koj, in Structure and Function of Plasma Proteins, Vol. 1, pp. 73-131, Plenum Press, London, 1974). The greatest increase in the serum concentrations of acute-phase proteins was found from the third to the seventh days postirradiation. At these times, the serum concentrations of alpha 2-macroglobulin, haptoglobin, fibrinogen and cysteine protease inhibitor were raised from two- to fivefold, whereas alpha 1-acid glycoprotein was increased sixfold. Incorporation of [35S]methionine into total serum and acute-phase proteins indicated that the increase in the concentration of the acute-phase proteins was preceded by their de novo synthesis in the liver. The results that were obtained by dot-blot analysis showed that the basic course of change in the relative mRNA concentrations in the liver for the acute-phase proteins examined correlated with the changes in their protein concentrations in the serum; only the relative increase in the concentration of alpha 1-acid glycoprotein mRNA was significantly lower than the increase in proteins in the serum, suggesting that a fraction of the serum alpha 1-acid glycoprotein had an extrahepatic origin. On the basis of these results we concluded that total-body irradiation increased the expression of acute-phase protein genes.

Relationship between early neuroendocrine response and severity of war injury according to the Red Cross Classification

The hypothesis that neuroendocrine response to military gunshot/missile (MG/M) wounds reflect the severity and type of wounds given by the Red Cross Wound Classification (RCWC), has been tested on 82 casualties of war in former Yugoslavia. Adrenaline (A), noradrenaline (N), Cortisol, triiodothyronine (T3), testosterone (TES) and prolactin (PRL) levels have been measured in blood samples taken on admission (2-18 hr after wounding) at Military Medical Academy. Neuroendocrine response to MG/M wounds has clearly reflected severity but not the type of wounds and it has been bidirectional, i.e. A, NA and cortisol levels positively related to, while T3 and TES levels were negatively related to severity of MG/M wounds. With regard to high compatibility between RCWC and Injury severity score (ISS) and the fact that magnitude of the neuroendocrine response is related to severity given by RCWC we have concluded that the RCWC is a good method of grading wound severity on the battlefield.

The effect of physostigmine on acid-base status in arterial and venous blood of anaesthetized rabbits following hypovolemic shock

1. The effects of physostigmine (70 micrograms kg-1, intravenously) on acid-base status in arterial and venous blood were studied in anaesthetized rabbits subjected to hemorrhagic hypovolemia. 2. Hemorrhagic shock was produced using intermittent bleeding of 50% of the estimated blood volume, during 30 min. Experimental group was treated with physostigmine (70 micrograms kg-1 body mass, intravenously) and the control group with the same volume (0.1 ml) of saline, immediately after bleeding. Blood samples were taken before and after bleeding (0, 15 and 60 min). 3. It was found that physostigmine increased the mean arterial blood pressure, did not change the heart rate, and improved survival of the animals. 4. These effects of physostigmine were associated with significant decrease in venous pH, produced mainly by increased PCO2. This can partly be explained in terms of additional vasoconstriction due to physostigmine action. 5. In arterial blood decreased pH, decreased standard bicarbonate, negative values of excess base and decreased PCO2 were observed both in physostigmine-treated and the control group of animals, indicating partly respiratory compensated metabolic acidosis. These findings indicate that the hypertensive effect of physostigmine in shock was not accompanied by more severe disturbance in arterial acid-base status than was observed in hypovolemic shock alone.

Brain PGD2 and PGE2 changes during posthaemorrhagic hypovolemia in rats

This study examined the changes of prostaglandins (PGs) E2 and D2 in brain structures of conscious rats during one hour period following acute bleeding. The analyses were performed in brain structures which are important for cardiovascular homeostasis (medulla oblongata, hypothalamus) and these which are not directly involved in central homeostatic mechanisms but are selectively vulnerable to low-flow states (hippocampus, cortex). Haemorrhage was induced by gradual withdrawal of blood from the cannulated right femoral artery (18 ml/kg, LD30) during a 3-min interval. The brain prostanoid contents were measured by radioimmunoassays. The bleeding induced significant changes in brain prostanoid content which were expressed to the highest extent in medulla oblongata and hypothalamus. The time course of the alterations in PGD2 and PGE2 contents was different in m. oblongata and hypothalamus from that in cortex and hippocampus. It was observed that PGE2 and PGD2 levels rose significantly in brain structures which are important for cardiovascular homeostasis and that their alterations were less expressed with different time course in structures which are selectively vulnerable to ischemia. Therefore, the authors suppose that the prostanoid changes in m. oblongata and hypothalamus are induced by the activation of central homeostatic mechanisms rather than by cerebral ischemia produced by haemorrhagic hypotension.

[Mechanisms of the favorable effect of spinal anesthesia in traumatic shock]

Changes in the level of total peptidoleukotriens-pLT (LTC4 + LTD4 + LTE4) and inositol triphosphates (IP3) were analyzed in the thalamus of rats subjected to "tourniquet" trauma of both hind extremities (LD50) depending on the power of afferent nociceptive nerve impulses. Prevention of spreading, i.e., reduction of painful impulses from the damaged regions was achieved by the spinal anesthesia with bupivacain-chloride immediately after removal of the rubber bandage. Together with pLT and IP3 levels determined by radio immunoassay, physiologic parameters (mean arterial pressure, blood-brain barrier permeability) were also analyzed. Morphologic changes in the thalamus of rats were analyzed by electron microscopy. Extreme increase of the thalamic pLT and IP3 levels in traumatized animals together with increased blood-brain barrier permeability were found. Spinal anesthesia prevented, i.e., reduced these pathologic changes. Authors conclude that afferent painful impulses cause pLT increase in the thalamus and could modify CNS response to the trauma.

[Eicosanoids in septic shock in rats]

In order to evaluate the role of eicosanoids in pathogenesis of septic shock, the dynamics of TxA2, PGE2 and peptidoleukotriene contents has been measured in the liver of rats with surgically induced septic shock (sesum resection). In the same time the general parameters have been followed up: survival, body temperature, hematocrit and glucose contents in the plasma of experimental animals. Aiming to differentiate the importance of some eicosanoids, immediately after surgery methyl prednisolone (phospholipase A2 inhibitor) or indomethacin (cyclooxigenase enzyme inhibitor) have been given. Based on own results the authors have concluded that in pathogenetic mechanisms of septic shock the main role have peptidoleukotrienes, lipooxygenase products of degradation of arachidonic acid.

[Mechanisms of the beneficial effect of indomethacin and nimodipine in the treatment of traumatic shock in rats]

Aiming to study the pathogenetic mechanisms of the disturbed function of the central nervous system in traumatic shock we have determined the dynamics of changes of eicosanoids (PGF2 alpha, TxB2, 6-keto-PGF1 alpha, peptidoleukotrienes) in the brain structures (medulla oblongata, hypothalamus) of the experimental animals subjected to bilateral trauma of the hind legs (tourniquet trauma, LD50). Considering that our previous data have shown the importance of eicosanoid mediatory system in the pathogenetic mechanisms of shock, we have studied possible use of prostaglandin synthesis inhibitors (indomethacin) and calcium channel antagonists (nimidipine) in traumatic shock. The authors have concluded that in the pathogenetic mechanism of the disturbed function of the CNS in traumatic shock the important role has peptidoleukotrienes as well as that the combined use of prostaglandin synthesis inhibitors and antagonists of voltage-dependent calcium channel would be useful in the therapy of the injured patients.

Frequency of the delta F508 deletion and G551D, R553X and G542X mutations in Yugoslav CF patients

A study was undertaken to find the frequency of the delta F508 deletion and those of the G551D, R553X and G524X mutations among the mainly Slavic population of Serbia, Bosnia, Herzegovina, and Montenegro and compare the frequencies determined with those in other European populations. The delta F508 mutation was found to account for about 70% of CF genes in central Jugoslavia, where its frequency is significantly higher than elsewhere in Southern European populations.

The effect of physostigmine on the haemorrhagic hypovolemia in anaesthetized rabbits

1. The effects of physostigmine (70 micrograms kg-1, intravenously) on mean arterial blood pressure, blood volume and survival were studied in anaesthetized rabbits subjected to haemorrhagic hypovolemia. 2. It was found that physostigmine increased the mean arterial blood pressure, increased the residual blood volume, decreased the haematocrit values and increased the survival of the animals. 3. The increase of blood pressure might be due to a general adrenergic activation produced by physostigmine, whereas the increase in plasma volume might be due to changes in pre- to postcapillary resistance ratio. 4. The beneficial effect of physostigmine might also be due to antagonism of humoral factors known to aggravate the hypovolemia (e.g. endogenous opioids).

[Primary blast injuries]

Blast injuries are defined as injuries occurring under effects of blast wave caused by explosion. They can be primary (exclusively due to blast wave effects), secondary (impact of fragments from the environmental material), and tertiary (whole body displacement and impact into solid objects or ground). Today they are result of war operations, terrorist actions and accidents in industry and households. One of the basic characteristics of primary blast injury are severe and even fatal damages, primarily of air-containing organs (respiratory and digestive tracts, auditory system) with simultaneous lack of visible external signs of injuries. Except for magnitude and duration (over-pressure) of the blast wave, the severity of injury depends also on other factors. When the blast wave reaches the lethal level, most of the lethal cases occur during the first 2 hours after injury, and those who survive have good chance for recovery. Some measures and procedures can lessen the harmful effects of blast wave, however, effective protection is not available.

[Characteristics of primary blast injuries at the beginning of armed conflict in Yugoslavia in 1991]

At the beginning of combat operations in Yugoslavia among 290 wounded members of the Y.P.A. and Territorial Defence sent to the treatment at the Military Medical Academy, 60 (20.7%) were with explosive mine wounds. In the group of 12 wounded with rupture of one or both tympanic membranes or with traumatic hearing impairment of various degrees, the chest x-ray was also performed. Radiologic signs characteristic of primary blast injury of the lung were found in a high percentage (42%). A possible relationship of primary auditory and primary nonauditory blast injury was discussed, and it has been concluded that more severe rupture of the eardrum in the injured by mine explosion can suggest the presence of primary blast injuries.

[Are the injuries caused by the "water bombs" dropped by the Canadair airplane blast injuries?]

During the forest fire extinguishing in summer using the fire-fighting amphibia (the Canadair) seven soldiers were injured by the "water bomb" dropped from the amphibia and two soldiers died. The way of injury occurrence as well as type and nature of injuries, imposed the question to the author: could it be a case of blast injuries, especially of primary blast injuries? Except for pure scientific reasons, a positive answer could have a practical importance both in regulation of work of persons engaged in fire combat on the ground during extinguishing of fire by the amphibia as well as for physician's work with those exposed to water impact from the plane and who could be eventually injured. Defining any mechanical injuries as transmission of the corresponding kinetic energy, the author considers that the mechanism of injury occurrence of the internal organs caused by the impact of the "water bomb" from the amphibia is the transmission of the energy impact wave into the body. The author has concluded that the impact of the "water bomb" dropped from the fire fighting amphibia can cause changes in the internal organs which are characteristic of primary blast injury. It is proposed that persons exposed to impact even in the absence of visible changes should be subjected to otorhinolaryngologic, and, in special cases, to pulmonary examinations.

[Morphologic changes in the tissues and organs of sheep in blast injuries caused by detonation of aerosol explosives]

The morphologic changes of the tissues and organs of sheep caused by effects of the overpressure wave due to the detonation of the aerosol explosive in the open air are analysed. The experiments were performed on 21 sheep of which 3 served as the control. All animals were autopsized and organ samples were taken for analysis. The most impressive pathologic changes were found in the upper respiratory ways and lungs in the form of massive haemorrhage, edema and emphysema as well as numerous and severe intraabdominal changes both of the air-containing and parenchymatous organs.

[Changes in serum enzyme values as possible indicators of the severity of blast injuries]

In order to detect biochemical parameters in the peripheral blood which would serve as an indicator of severity of blast injuries, the enzyme dynamics (creatine kinase, aspartat transaminase, alanin transaminase, lactic dehydrogenase, alkaline phosphatase, angiotensin convertase) has been followed up in the serum of sheep. The significant increase was found in the values of creatine kinase, aspartat transaminase and alanine transaminase in the serum of the experimental animals an hour after effects of the blast wave. The authors have concluded that changes of the mentioned enzymes can serve as one of signs of damages of the lungs and gastrointestinal tract caused by blast wave in the early posttraumatic period.

[Pathogenesis of pulmonary edema caused by blast waves]

In the study of pathogenetic mechanisms of pulmonary edema to blast wave generated by detonation of the aerosol explosive in the open air, the dynamics of changes of the eicosanoid contents, the products of the energy metabolism as well as the glucose metabolism in the lung tissue of sheep have been examined. On the basis of data from the literature as well as own results the authors have given the original scheme of possible mechanisms of pulmonary edema caused by effects of the blast wave.

[Pathophysiologic reactions in sheep to blast waves from detonation of aerosol explosives]

In the controlled field experiments 18 sheep were exposed to the detonation of the aerosol explosive generating the blast wave necessary to produce death in 50% of cases. The time of death and characteristic damages on the predilection sites of some organs are interpreted as blast type injuries. General response of the body to blast wave was similar to the one produced by other etiological factors. A special characteristic of the experiment was the frequency and severity of pathologic changes on the internal organs of the chest and abdomen. According to the authors' opinion the severity and type of pathologic changes could be explained by effects of the complex blast wave generated by detonation of the aerosol explosives.