Complex Biochemical Changes Research Articles

Characterization of wound responses of stems of paper birch (Betula papyrifera) and European white birch (Betula pendula)

Plants respond to feeding injury by chewing insects by inducing both a general response to mechanical wounding and a specific response to herbivore-associated elicitors. In both cases, plant response involves complex biochemical and physiological changes. We compared chemical and physical responses of paper birch (B. papyrifera) and European white birch (B. pendula) stems to mechanical injury to determine if aspects of their wound response correspond with the much higher resistance of paper birch to bronze birch borer (Agrilus anxius). We also characterized stem responses to mechanical wounding plus bronze birch borer larval homogenate to determine if larval cues elicited a more specific response than mechanical wounding alone. In both species, wounding decreased concentrations of individual phenolics, total phenolics, and condensed tannins, perhaps because they were diverted to lignin biosynthesis, the concentration of which increased. Nitrogen concentration increased in both species while free amino acid concentrations declined, perhaps because they were utilized to synthesize proteins. Application of larval homogenate did not elicit a response different from that induced by mechanical injury. When comparing wound responses of the two birch species, phenolic profiles differed most conspicuously. However, multivariate analyses revealed no differences between constitutive and wound-induced phenolic profiles within each species, and the rate of wound periderm growth was equivalent between species. These results suggest that components of the wound response we measured may not contribute to interspecific variation in bronze birch borer resistance of paper birch and European white birch.

The grape berry-specific basic helix–loop–helix transcription factor VvCEB1 affects cell size

The development of fleshy fruits involves complex physiological and biochemical changes. After fertilization, fruit growth usually begins with cell division, continues with both cell division and expansion, allowing fruit set to occur, and ends with cell expansion only. In spite of the economical importance of grapevine, the molecular mechanisms controlling berry growth are not fully understood. The present work identified and characterized Vitis vinifera cell elongation bHLH protein (VvCEB1), a basic helix–loop–helix (bHLH) transcription factor controlling cell expansion in grape. VvCEB1 was expressed specifically in berry-expanding tissues with a maximum around veraison. The study of VvCEB1 promoter activity in tomato confirmed its specific fruit expression during the expansion phase. Overexpression of VvCEB1 in grape embryos showed that this protein stimulates cell expansion and affects the expression of genes involved in cell expansion, including genes of auxin metabolism and signalling. Taken together, these data show that VvCEB1 is a fruit-specific bHLH transcription factor involved in grape berry development.

Metabolic and Proteomic Profiling of Diapause in the Aphid Parasitoid Praon volucre

BackgroundDiapause, a condition of developmental arrest and metabolic depression exhibited by a wide range of animals is accompanied by complex physiological and biochemical changes that generally enhance environmental stress tolerance and synchronize reproduction. Even though some aspects of diapause have been well characterized, very little is known about the full range of molecular and biochemical modifications underlying diapause in non-model organisms.Methodology/Principal FindingsIn this study we focused on the parasitic wasp, Praon volucre that exhibits a pupal diapause in response to environmental signals. System-wide metabolic changes occurring during diapause were investigated using GC-MS metabolic fingerprinting. Moreover, proteomic changes were studied in diapausing versus non-diapausing phenotypes using a combination of two-dimensional differential gel electrophoresis (2D-DIGE) and mass spectrometry. We found a reduction of Krebs cycle intermediates which most likely resulted from the metabolic depression. Glycolysis was galvanized, probably to favor polyols biosynthesis. Diapausing parasitoids accumulated high levels of cryoprotective polyols, especially sorbitol. A large set of proteins were modulated during diapause and these were involved in various functions such as remodeling of cytoskeleton and cuticle, stress tolerance, protein turnover, lipid metabolism and various metabolic enzymes.Conclusions/SignificanceThe results presented here provide some first clues about the molecular and biochemical events that characterize the diapause syndrome in aphid parasitoids. These data are useful for probing potential commonality of parasitoids diapause with other taxa and they will help creating a general understanding of diapause underpinnings and a background for future interpretations.

Does Manipulating Local Surgical Wound Cytokines Improve Surgical Outcomes?

Surgical trauma produces complex local biochemical changes that contribute to inflammation and acute postoperative pain, and in some cases to chronic pain.1 Tissue injury induces an increase in the complex cascade of inflammatory cytokines that can induce peripheral and central nervous system sensitization, leading to hyperalgesia.2 In a set of articles in this issue of the journal, Hu et al.3,4 describe the role of one of these inflammatory cytokines, interleukin (IL)-1β, in postsurgical wound healing and acute postoperative pain. In a rodent model of incision pain, they demonstrated that the antiinflammatory cytokine, IL1ra, which antagonizes the binding of IL-1β to its receptor, decreases postoperative mechanical hypersensitivity when administered intraperitoneally. In addition, the concentration of other inflammatory cytokines, such as IL-6 and tumor necrosis factor (TNF)α, were reduced in wound skin tissue. This complements their human studies, which showed that IL-1β stimulated cytokine production, especially IL-8, in vitro in primary human keratinocytes, and that IL-1β and IL-8 levels were highly correlated in surgical wound exudates from both cesarean incisions and sunburn-induced blisters. The authors suggest that because a commercially available recombinant version of IL1ra, anakinra, is already in use in rheumatoid arthritis patients, a clinical trial to assess its value in improving wound healing and reducing pain when administered perioperatively can be considered. What are the main issues to consider before using any type of cytokine modulator to reduce inflammation and pain during the perioperative period? First, how serious a problem is wound healing and acute postoperative pain for each type of surgery being considered? Second, are some of the inflammatory immune mediators necessary as part of the normal defense of the surgical wound to prevent infection? With small incisions of skin and underlying muscle with minimal retraction, postoperative outcomes are usually good and recovery is uneventful. Therefore, cytokine manipulation may not be needed. However, for major types of surgery, e.g., joint replacement surgery, spine, or thoracotomy, acute postoperative pain may be severe and can delay rehabilitation. In addition, with procedures such as knee replacement surgery and thoracotomy, the incidence of persistent postsurgical pain is relatively high5; therefore, there are even more incentives to consider reducing postsurgical inflammation.1 The relative importance of each cytokine may differ depending on the type of surgery. With hip replacement surgery, concentrations of IL-1β, IL-6, and IL-8 increase in hip drain exudates, whereas TNFα levels decrease.6 Similarly, as described in this issue of the journal, in cesarean delivery, local inflammatory mediators such as substance P, IL-1, IL-6, IL-8, and IL-10 are increased.7 However, it is not known whether controlling surgical site IL-1β release or binding would be more important than suppressing IL-6 or IL-8 in improving wound healing and reducing pain. In the earlier stages of wound healing (up to 24 hours), neutrophils are the dominant cell type in the local immune response,8–10 and after hip replacement surgery, there is upregulation of gene expression for such inflammatory modulators as macrophage migration inhibitory factor, IL1ra itself, the chemokine CCL20, and receptors for IL-8 and IL-18 in neutrophils extracted from the wound drainage.11 Recent basic12 and clinical studies13 all point to IL-1 as the main local tissue receptor type correlated with postoperative analgesia. Choosing the correct dose of the IL-1 receptor blocker, anakinra, for a clinical trial affecting surgical outcomes may not be obvious, based on approved doses for rheumatoid arthritis. In the rodent incision model, the anakinra dose to reduce postoperative mechanical hypersensitivity was 100 mg/kg. However, the daily dose in rheumatoid arthritis patients is 100 mg,4,12 which is approximately 1 mg/kg. Whereas the antihyperalgesic doses in rodent pain models are often much larger than doses used clinically to reduce pain, it is possible that the maximum approved anakinra dose for patients may be inadequate to decrease postoperative pain. In a review of clinical trials using anakinra for chronic rheumatoid arthritis, the incidence of serious infections was 1.8% in the anakinra group versus 0.6% in the placebo group.14 Although for cutaneous wounds this may not be a real clinical issue, for major joint replacement surgery, an infected prosthesis could be detrimental. All of the above issues apply not just to anakinra, but to inflammatory cytokine modulators in general (e.g., TNFα inhibitors: etanercept, adalimumab, infliximab). The 2 articles in this journal,3,4 along with previous animal studies,15,16 provide a rationale for IL1ra administration in the perioperative setting. Nevertheless, it is important that the choice of surgery for an initial clinical trial is chosen judiciously. A key consideration is that the surgery in question be one in which surgical outcomes have a relatively high incidence of acute pain, and possibly chronic pain, so that a successful treatment will be clinically and statistically significant. In addition, the type of surgery chosen for study should be one in which infection would be relatively easy to treat, should one occur.

Effects of Cadmium on Locomotor Activity Rhythms of the Amphipod Gammarus aequicauda

Behavioural responses are linked to complex biochemical and physiologic changes and may act as sensitive indicators of the sublethal effects of pollutants. This article investigates changes in the locomotor activity rhythms of the amphipod Gammarus aequicauda exposed to cadmium (Cd) as a model to study the effect of pollutants on an ecologically important species. Under a 12:12 h light-to-dark cycle, G. aequicauda showed a strict nocturnal rhythm, with 90.2±0.4% of their total daily activity occurring during the night. Under constant darkness, circadian rhythms persisted for 10 days, with a mean periodicity of 24.32 h, thus confirming endogenous control. Exposure to sublethal concentrations of Cd (0.16, 0.20, 0.24, and 0.28 mg l(-1)) did not change the nocturnal activity patterns of G. aequicauda, although their swimming activity during the night was significantly decreased by exposure to concentrations of 0.24 and 0.28 mg Cd l(-1). In conclusion, locomotor activity bioassays using the amphipod G. aequicauda appeared to be a sensitive indicator of Cd contamination, and sensitivity and tolerance to Cd in short-term bioassays may depend on the time of the day tests are carried out. These results provide further support for the idea that behavioural end points in amphipods are useful indicators of pollutant exposure and that future studies should take circadian rhythms into consideration.

Transient Receptor Potential Melastatin 2 Expression is Increased Following Experimental Traumatic Brain Injury in Rats

Traumatic brain injury (TBI) elicits a sequence of complex biochemical changes including oxidative stress, oedema, inflammation and excitotoxicity. These factors contribute to the high morbidity and mortality following TBI, although their underlying molecular mechanisms remain poorly understood. Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel, highly expressed in the brain and immune cells. Recent studies have implicated TRPM2 channels in processes involving oxidative stress, inflammation and cell death. However, no studies have investigated the role of TRPM2 in TBI pathophysiology. In the present study, we have characterised TRPM2 mRNA and protein expression following experimental TBI. Adult male Sprague Dawley rats were injured using the impact-acceleration model of diffuse TBI with survival times between 5 and 5 days. Real-time RT-PCR (including reference gene validation studies) and semi-quantitative immunohistochemistry were used to quantify TRPM2 mRNA and protein levels, respectively, following TBI. Significant increases in TRPM2 mRNA and protein expression were observed in the cerebral cortex and hippocampus of injured animals, suggesting that TRPM2 may contribute to TBI injury processes such as oxidative stress, inflammation and neuronal death. Further characterisation of how TRPM2 may contribute to TBI pathophysiology is warranted.

Studies on plant defense signaling and host specificity

The induction of plant defense in response to molecular signals during infection by pathogens leads to complex biochemical and genetic changes, including the production of reactive oxygen species, phytoalexins, antioxidants, and signaling molecules. Although much research has dealt with signal transduction and defense-related genes in many plant species, little is known about signaling mechanisms in citrus species, one of the most economically important group of fruits. As a first step toward understanding the mechanism of defense response in citrus, I performed molecular experiments using rough lemon (Citrus jambhiri). In addition, I also performed a study on the MAP kinase signaling pathway using tobacco, a useful plant to analyze the signaling pathway.

Freezing Tolerance and Cold Acclimation in Guava (Psidium guajava L.)

Guava (Psidium guajava L.) is a tropical evergreen tree that tolerates a wide range of frost-free environments. In recent years, the American market demand for exotic and nutritious fruits, like guava, has been increasing, and, with a long harvest period, guava can be a potential alternative, high-value cash crop in the United States. However, the major limitation with commercializing guava cultivation in the United States is its low cold tolerance. In this article, we studied the physiology of freezing tolerance and cold acclimation in guava. Laboratory freeze–thaw tests (on leaves), shoot growth and leaf relative water content measurements, leaf anthocyanin content analyses, and leaf protein analyses were performed on nonacclimated and cold-acclimated guava cultivars Lucknow-49 and Ruby × Supreme. The leaf freezing tolerance (expressed as LT50 values) of nonacclimated tissues was ≈–2.5 °C and significantly enhanced to ≈–4.4 °C after an environmentally controlled cold acclimation regime for both cultivars. However, when compared based on actual injury sustained by leaves at various freezing temperatures in a freeze–thaw test, ‘Ruby × Supreme’ exhibited significantly less injury than ‘Lucknow-49’ at most temperatures. Growth and leaf relative water content reduced, whereas leaf anthocyanins accumulated during cold acclimation. Leaf protein analyses, which were performed after cold acclimation and drought stress, revealed that four proteins (69, 48, 23.5, and 17.4 kDa) accumulated in response to low temperatures, and two proteins (17.4 and 16 kDa) accumulated in response to drought stress. Antidehydrin immunoblots revealed that one common 17.4 kDa dehydrin accumulated in response to cold and drought stresses. Our data indicate that guava possesses leaf freezing tolerance, exhibits cold acclimation ability, and that ‘Ruby × Supreme’ leaves are relatively more freezing-tolerant than ‘Lucknow-49’ when compared up to –4 and –8 °C for nonacclimated and cold-acclimated tissues, respectively. Cold acclimation in guava appears to be a multifactorial process involving complex physiological and biochemical changes and also overlapping responses with drought stress.

A Genomics Approach Using Expressed Sequence Tags and Microarrays in Ripening Apple Fruit (Malus domestica Borkh.)

Apple (Malus domestica Borkh.), an important horticultural crop, produces human health-promoting metabolites during fruit ripening. Because that process, which involves complex biochemical and physiological changes, is genetically programmed, molecular and genetic approaches have been taken to understand the associated cellular mechanisms. The release of 151,687 apple expressed sequence tags (ESTs) into a public database has made possible large-scale studies of expression. Analysis of apple ESTs allows for the identification and characterization of genes with potential roles in fruit development, particularly those related to aroma production and protein degradation during ripening. Apple cDNA and oligonucleotide microarrays have been generated for more comprehensive examinations. Such tools are powerful means for elucidating the molecular events involved in metabolite biosynthesis and physiological changes and will also enable researchers to understand how to control that ripening process.

β3-Adrenergic Receptor Subtype Signaling In Senescent Heart

β3-Adrenergic Receptor Subtype Signaling In Senescent Heart

Red cell transfusion in medicine: Future challenges

Many side-effects of red blood cell transfusion have been described. They include iron-overload, as well as allo- and autoantibody formation against red cells. During storage, erythrocytes undergo complex structural and biochemical changes. It has been suggested that accelerated and/or aberrant forms of the physiological erythrocyte aging process underlie the red cell storage lesion. This storage lesion may contribute to side-effects of transfusion as endothelial damage by release of internal erythrocyte constituents, (pro)inflammatory consequences, hampered microcirculation and oxygen delivery. Understanding the process that determines the fate of red blood cells after transfusion may contribute to the prevention of side-effects after red blood cell transfusion. This should be the focus of research on red blood cell transfusion in clinical transfusion medicine.

Plasma lipids are altered in Gaucher disease: Biochemical markers to evaluate therapeutic intervention

Enzyme replacement therapy has been in clinical practice for the non-neuronopathic form of Gaucher disease for 15 years. However, the wide phenotypic variability in this disorder poses challenges to clinicians to assess patient severity and disease progression in order to effectively manage patients. Once therapy is initiated, methods to monitor the complex biochemical changes associated with the disease, and the response of these changes to therapy, are required in order to tailor therapy regimens to individual patients. We have evaluated the suitability of plasma sphingolipids and phospholipids as biochemical markers of disease burden and the efficacy of therapy to reduce that burden. Over 60 lipid species were measured using electrospray ionization-tandem mass spectrometry in plasma from controls and Gaucher patients, pre- and post-therapy. Glucosylceramide, molecular species of phosphatidylglycerol and G M3 ganglioside were elevated in Gaucher disease, whereas species of ceramide, dihexosylceramide and sphingomyelin were decreased. Multivariate analysis enabled us to calculate the combined response of these lipids to therapy in Gaucher patients and correlate them with patient severity. Plasma lipids are proposed to be useful biomarkers for Gaucher disease.

THE INFLUENCE OF INCORPORATED<sup>137</sup>Cs ON STRUCTURAL COMPONENTS OF THE MYOCARDIUM

In the work the morphometric analysis of a myocardium tissue of the experimental animals, undergone impact of incorporated radionuclides has been carried out. The given stress factor causes the adaptable reaction demonstrated in a complex biochemical and morphfunctional changes. The revealed structural infringements are the following: decrease in muscular mass of myocardium tissue and cardiomiocytes quantity reduction on a background of a hypertrophy of their nuclei. Reduced to collagenazin and growth of connective tissues strom and mass dilation of a coronary capillary network. The arisen structural infringements can serve as the precondition of development of a pathology development.

Expression of MdCAS1 and MdCAS2, encoding apple β-cyanoalanine synthase homologs, is concomitantly induced during ripening and implicates MdCASs in the possible role of the cyanide detoxification in Fuji apple (Malus domestica Borkh.) fruits

Fruit ripening involves complex biochemical and physiological changes. Ethylene is an essential hormone for the ripening of climacteric fruits. In the process of ethylene biosynthesis, cyanide (HCN), an extremely toxic compound, is produced as a co-product. Thus, most cyanide produced during fruit ripening should be detoxified rapidly by fruit cells. In higher plants, the key enzyme involved in the detoxification of HCN is beta-cyanoalanine synthase (beta-CAS). As little is known about the molecular function of beta-CAS genes in climacteric fruits, we identified two homologous genes, MdCAS1 and MdCAS2, encoding Fuji apple beta-CAS homologs. The structural features of the predicted polypeptides as well as an in vitro enzyme activity assay with bacterially expressed recombinant proteins indicated that MdCAS1 and MdCAS2 may indeed function as beta-CAS isozymes in apple fruits. RNA gel-blot studies revealed that both MdCAS1 and MdCAS2 mRNAs were coordinately induced during the ripening process of apple fruits in an expression pattern comparable with that of ACC oxidase and ethylene production. The MdCAS genes were also activated effectively by exogenous ethylene treatment and mechanical wounding. Thus, it seems like that, in ripening apple fruits, expression of MdCAS1 and MdCAS2 genes is intimately correlated with a climacteric ethylene production and ACC oxidase activity. In addition, beta-CAS enzyme activity was also enhanced as the fruit ripened, although this increase was not as dramatic as the mRNA induction pattern. Overall, these results suggest that MdCAS may play a role in cyanide detoxification in ripening apple fruits.

PATHOMORPHOLOGICAL CHARACTERISTIC OF THE VASCULAR COMPONENT OF COMMUNICATION SYSTEMS AT THE CRANIOCEREBERAL TRAUMA

The craniocereberal trauma is one of the major aspects of research in forensic medicine that is caused by the big frequency, difficulties of diagnostics and weight of her current, is frequent with a lethal outcome. The craniocereberal trauma causes the general adaptable reaction shown in a complex pathophisiological, biochemical and morphological changes not only in a zone of direct mechanical damage, but also in nervous, endocrin, cardiovascular and other systems. The data of own researches of communication systems are submitted.

Rapid Determination of Swiss Cheese Composition by Fourier Transform Infrared/Attenuated Total Reflectance Spectroscopy

There is a need for rapid and simple techniques that can be used to predict the quality of cheese. The aim of this research was to develop a simple and rapid screening tool for monitoring Swiss cheese composition by using Fourier transform infrared spectroscopy. Twenty Swiss cheese samples from different manufacturers and degree of maturity were evaluated. Direct measurements of Swiss cheese slices (∼0.5g) were made using a MIRacle 3-reflection diamond attenuated total reflectance (ATR) accessory. Reference methods for moisture (vacuum oven), protein content (Kjeldahl), and fat (Babcock) were used. Calibration models were developed based on a cross-validated (leave-one-out approach) partial least squares regression. The information-rich infrared spectral range for Swiss cheese samples was from 3,000 to 2,800cm−1 and 1,800 to 900cm−1. The performance statistics for cross-validated models gave estimates for standard error of cross-validation of 0.45, 0.25, and 0.21% for moisture, protein, and fat respectively, and correlation coefficients r>0.96. Furthermore, the ATR infrared protocol allowed for the classification of cheeses according to manufacturer and aging based on unique spectral information, especially of carbonyl groups, probably due to their distinctive lipid composition. Attenuated total reflectance infrared spectroscopy allowed for the rapid (∼3-min analysis time) and accurate analysis of the composition of Swiss cheese. This technique could contribute to the development of simple and rapid protocols for monitoring complex biochemical changes, and predicting the final quality of the cheese.

A global reorganization of the metabolome in Arabidopsis during cold acclimation is revealed by metabolic fingerprinting

Many plants, including Arabidopsis, increase their freezing tolerance in response to low, non‐freezing temperatures. This process is known as cold acclimation and involves many complex biochemical changes at the level of the metabolome. Our goal was to examine the effects of cold acclimation on the metabolome using a non‐targeted metabolic fingerprinting approach. Multivariate data analyses indicate that, in Arabidopsis, a global reprogramming of metabolism occurs as a result of cold acclimation. By measuring an entire spectrum of putative metabolites based on mass‐to‐charge (m/z) ratios, vs. an individual or group of metabolite(s), a comprehensive, unbiased assessment of metabolic processes relative to cold acclimation was determined. Whereas leaves shifted to low temperature present metabolic profiles that are constantly changing, leaves developed at low temperature demonstrate a stable complement of components. Although it appears that some metabolic networks are modulated by the environment, others require development under low‐temperature conditions for adjustment. Understanding how metabolism as a whole is regulated allows the integration of cellular, physiological and ecological attributes in a biological system, a necessity if complex traits, such as freezing tolerance, are to be modified by breeding or genetic manipulation.

Changes in IGF activities in human diabetic vitreous.

Müller cells, the principal glia of the retina, generate tractional forces in response to IGF-I and platelet-derived growth factor and are present in diabetic fibro-vascular scar tissues causing traction retinal detachment. While diabetes-associated increases in vitreous IGFs have been reported, paradoxically high concentrations of these same growth factors in normal vitreous suggest the presence of more complex mechanisms regulating growth factor bioavailability. To define diabetes-associated changes in vitreous biological activity, the stimulatory effects of 68 samples were evaluated using Müller cell tractional force generation as a target bioassay. Dose-response profiles were used to calculate vitreous specific activity (per unit protein) and total vitreous activity (per unit volume). Vitreous samples from patients lacking diabetes or other retinal pathology had undetectable or low activities, whereas diabetic retinopathy was associated with 6.9- and 8.7-fold increases in vitreous specific and total activities, respectively. Secondary analyses revealed no activity differences associated with patient sex, age, or the presence of vitreous hemorrhage. However, compared with diabetes alone, the presence of proliferative diabetic retinopathy was associated with additional 2.3-fold increases in vitreous specific and total activities. Vitreous dose-response assays performed with and without growth factor-neutralizing antibodies enable attribution of vitreous activity to IGFs (53.9%) and, to a lesser extent, platelet-derived growth factors (14.5%). Because the observed increases in vitreous growth factor activity grossly exceed the reported increases in growth factor concentration, these data indicate that diabetes-associated changes in vitreous biological activity involve more complex biochemical changes that ultimately yield increased growth factor bioavailability and/or Müller cell responsiveness.

Correlation of structural development and differential expression of invasion-related molecules in schizonts of Plasmodium falciparum.

During asexual development Plasmodium schizonts undergo a series of complex biochemical and structural changes. Using tightly synchronized cultures of 2 P. falciparum lines (clone C10 and strain ITO4) for light microscopy and fluorescence imaging we monitored the timing and sequence of expression of proteins associated with invasion-related organelles. Antibodies to rhoptry, micronemal and dense granule proteins (Rhoptry Associated Protein 1, Apical Membrane Antigen 1, Erythrocyte Binding Antigen 175, Ring-infected Erythrocyte Surface Antigen) and to pellicle-associated proteins (Merozoite Surface Protein 1, PfMyosin-A) were used. Clone C10 developed faster than ITO4; this difference was also found in the timing of protein expression seen by immunofluorescence. Light microscopic data were combined with transmission electron microscopic analysis using serial sectioning of ITO4 schizonts to determine nuclear number and organellar development. Thus a timetable of schizont structural maturation was established. Generally, the timing of organelle-specific antigen expression correlates well with the ultrastructural data. Rhoptries are formed mainly between second and fourth nuclear divisions, micronemes between the end of the fourth nuclear division and merozoite separation from the residual body, while dense granules are generated mainly after the micronemes. PfAMA-1 appears in micronemes before EBA-175, suggesting micronemal heterogeneity.

Variation in cyclooxygenase expression levels within the colorectum.

The positive association of decreased risk of colorectal cancer with nonsteroidal antiinflammatory drug (NSAID) use, combined with the observation that cyclooxygenase(COX)-2 is present in a majority of colorectal tumors, has led to the proposed use of isozyme-specific COX inhibitors as preventive agents in polyp and tumor formation in the colon. However, the exact biochemical mechanisms and disease stage at which reduced risk is mediated remain somewhat controversial, in part because of the complex biochemical changes that occur during the progression from aberrant crypt to polyp to tumor. In this study, COX-1 and COX-2 protein expression levels were determined in sets of tumor and normal colon tissue. Changes were characterized in COX-1 and COX-2 expression within individuals, in relation to such factors as sex, tumor grade, and location in the colorectum. COX-1 expression levels were found to be significantly reduced in tumors compared to matched normal tissues (Dunn's method, P < 0.05). Additionally, COX-1 expression was decreased in stage T3 tumors as compared to stage T2 tumors (Student's t-test, P = 0.009). Similar to previous reports, COX-2 protein expression was present in 73% of the tumors studied and appeared to be independent of tumor grade and sex. Interestingly, decreased COX-2 expression correlated with tumor occurrence in rectal mucosa (Wilcoxon two-sample test, P < 0.05). These results warrant further investigation, especially the identification of determinants that would predict which populations would be most responsive to COX-2 inhibition as a means of colorectal cancer chemoprevention.