Ingestion Of Inhibitors Research Articles

Cholinergic crisis caused by ingesting topical carpronium chloride solution: A case report

A cholinergic crisiss is a state characterized by excess acetylcholine owing to the ingestion of cholinesterase inhibitors or cholinergic agonists. We report the first case of a cholinergic crisis after the ingestion of a carpronium chloride solution, a topical solution used to treat alopecia, seborrhea sicca, and vitiligo. An 81-year-old woman with no prior medical history was transported to our emergency department because the patient had disturbance of consciousness after ingesting three bottles of FUROZIN® solution (90 mL, 4500 mg as carpronium chloride). A family member who found the patient called for emergency medical services (EMS) personnel, who contacted the patient ten minutes after ingestion. The patient's Glasgow Coma Scale score was 12 (E4V3M5), and vital signs were as follows: blood pressure, 80/40 mmHg; heart rate, 40 beats/min. The patient vomited repeatedly in the ambulance. On arrival to the ED, the patient's systolic blood pressure and heart rate temporarily decreased to 80 mmHg and 40 beats/min, respectively. Seventy-eight minutes after ingestion, gastric lavage was performed. The patient's symptoms, which included excess salivation, sweating, and hot flush, improved 24 h after ingestion, and the patient's vital signs stabilized without atropine or vasopressors. On the second day of admission, the patient was examined by a psychiatrist and discharged without suicidal ideation. Carpronium chloride has a chemical structure similar to that of acetylcholine; therefore, it exhibits both cholinergic and local vasodilatory activities. There is limited information on the pharmacokinetics of ingested carpronium chloride; therefore, physicians should be made aware that ingesting a carpronium chloride solution may cause a cholinergic crisis.

The role of aspirin desensitization followed by oral aspirin therapy in managing patients with aspirin-exacerbated respiratory disease: A Work Group Report from the Rhinitis, Rhinosinusitis and Ocular Allergy Committee of the American Academy of Allergy, Asthma & Immunology

Aspirin-exacerbated respiratory disease (AERD) is characterized by the clinical triad of chronic rhinosinusitis with nasal polyps, asthma, and an intolerance to medications that inhibit the cycloxgenase-1 enzyme. Patients with AERD on average have more severe respiratory disease compared with patients with chronic rhinosinusitis with nasal polyps and/or asthma alone. Although patients with AERD traditionally develop significant upper and lower respiratory tract symptoms on ingestion of cycloxgenase-1 inhibitors, most of these same patients report clinical benefit when desensitized to aspirin and maintained on daily aspirin therapy. This Work Group Report provides a comprehensive review of aspirin challenges, aspirin desensitizations, and maintenance aspirin therapy in patients with AERD. Identification of appropriate candidates, indications and contraindications, medical and surgical optimization strategies, protocols, medical management during the desensitization, and recommendations for maintenance aspirin therapy following desensitization are reviewed. Also included is a summary of studies evaluating the clinical efficacy of aspirin therapy after desensitization as well as a discussion on the possible cellular and molecular mechanisms explaining howthis therapy provides unique benefit to patients with AERD.

Inhibition kinetics of digestive proteases for Anticarsia gemmatalis.

Anticarsia gemmatalis Hübner, 1818 (Lepidoptera) is a major pest of soybean in the Brazil. It is known that the reduction of proteolytic activity by the ingestion of protease inhibitors reduces digestion and larval development of the insects. Control via inhibition of the digestive enzymes necessitates deeper knowledge of the enzyme kinetics and the characterization of the inhibition kinetics of these proteases, for better understanding of the active centers and action mechanisms of this enzyme. Trypsin-like proteases found in the gut of Anticarsia gemmatalis were purified in a p-aminobenzamidine agarose column. Kinetic characterization showed KM 0.503 mM for the L-BApNA substrate; Vmax= 46.650 nM s-1; Vmax/[E]= 9.256 nM s-1 mg L-1 and Vmax/[E]/KM= 18.402 nM s-1 mg L-1 mM. The Ki values for the inhibitors benzamidine, berenil, SKTI and SBBI were 11.2 µM, 32.4 µM, 0.25 nM and 1.4 nM, respectively, and all revealed linear competitive inhibition. The SKTI showed the greatest inhibition, which makes it a promising subject for future research to manufacture peptide mimetic inhibitors.

Toxicity of agents used for opioid withdrawal: a case-based approach.

Toxicity of agents used for opioid withdrawal: a case-based approach.

A trial of type 12 purinergic (P2Y12) receptor inhibition with prasugrel identifies a potentially distinct endotype of patients with aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by asthma, recurrent nasal polyposis, and respiratory reactions on ingestion of COX-1 inhibitors. Increased numbers of platelet-leukocyte aggregates are present in the sinus tissue and blood of patients with AERD compared with that of aspirin-tolerant patients, and platelet activation can contribute to aspirin-induced reactions. We sought to determine whether treatment with prasugrel, which inhibits platelet activation by blocking the type 12 purinergic (P2Y12) receptor, would attenuate the severity of sinonasal and respiratory symptoms induced during aspirin challenge in patients with AERD. Forty patients with AERD completed a 10-week, double-blind, placebo-controlled crossover trial of prasugrel. All patients underwent oral aspirin challenges after 4weeks of prasugrel and after 4weeks of placebo. The primary outcome was a change in the provocative dose of aspirin that would elicit an increase in Total Nasal Symptom Score (TNSS) of 2 points. Changes in lung function, urinary eicosanoids, plasma tryptase, platelet-leukocyte aggregates, and platelet activation were also recorded. Prasugrel did not significantly change the mean increase in TNSS of 2 points (79±15 for patients receiving placebo and 139±32 for patients receiving prasugrel, P=.10), platelet-leukocyte aggregates, or increases in urinary leukotriene E4 and prostaglandin D2 metabolite levels during aspirin-induced reactions in the study population as a whole. Five subjects (responders) reacted to aspirin while receiving placebo but did not have any reaction to aspirin challenge after the prasugrel arm. In contrast to prasugrel nonresponders (35 subjects), the prasugrel responders had smaller reaction-induced increases in TNSS; did not have significant aspirin-induced increases in urinary leukotriene E4, prostaglandin D2 metabolite, or thromboxane B2 levels; and did not display increases in serum tryptase levels during aspirin reactions on the placebo arm, all of which were observed in the nonresponders. In the overall study population, prasugrel did not attenuate aspirin-induced symptoms, possibly because it failed to decrease the frequencies of platelet-adherent leukocytes or to diminish aspirin-induced mast cell activation. In a small subset of patients with AERD who had greater baseline platelet activation and milder upper respiratory symptoms during aspirin-induced reactions, P2Y12 receptor antagonism with prasugrel completely inhibited all aspirin-induced reactionsymptoms, suggesting a contribution from P2Y12 receptor signaling in this subset.

Aspirin induces IL-4 production: augmented IL-4 production in aspirin-exacerbated respiratory disease.

Aspirin hypersensitivity is a hallmark of aspirin-exacerbated respiratory disease (AERD), a clinical syndrome characterized by the severe inflammation of the respiratory tract after ingestion of cyclooxygenase-1 inhibitors. We investigated the capacity of aspirin to induce interleukin-4 (IL-4) production in inflammatory cells relevant to AERD pathogenesis and examined the associated biochemical and molecular pathways. We also compared IL-4 production in peripheral blood mononuclear cells (PBMCs) from patients with AERD vs aspirin-tolerant asthma (ATA) upon exposure to aspirin. Aspirin induced IL-4 expression and activated the IL-4 promoter in a report assay. The capacity of aspirin to induce IL-4 expression correlated with its activity to activate mitogen-activated protein kinases, to form DNA–protein complexes on P elements in the IL-4 promoter and to synthesize nuclear factor of activated T cells, critical transcription factors for IL-4 transcription. Of clinical importance, aspirin upregulated IL-4 production twice as much in PBMCs from patients with AERD compared with PBMCs from patients with ATA. Our results suggest that IL-4 is an inflammatory component mediating intolerance reactions to aspirin, and thus is crucial for AERD pathogenesis.

Platelet activation markers overexpressed specifically in patients with aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by respiratory reactions on ingestion of COX-1 inhibitors and cysteinyl leukotriene overproduction. The hypersensitivity reaction is induced by low doses of aspirin that inhibit COX-1 in platelets. We sought to explore the role of platelets in the pathogenesis of AERD in patients under stable conditions and during an aspirin challenge test. Stable patients with AERD (n= 30), aspirin-tolerant asthma (ATA; n= 21), or idiopathic chronic eosinophilic pneumonia (n= 10) were enrolled. Platelet activation was estimated based on expression levels of P-selectin (CD62P), CD63, CD69, and GPIIb/IIIa (PAC-1) in peripheral platelets; percentages of circulating platelet-adherent leukocytes; and plasma levels of soluble P-selectin (sP-selectin) and soluble CD40 ligand (sCD40L). In the stable condition, expression of all surface markers on platelets, the percentage of platelet-adherent eosinophils, and the plasma levels of sP-selectin and sCD40L were significantly higher in patients with AERD compared with those in patients with ATA. P-selectin and CD63 expression on platelets and plasma sP-selectin and sCD40L levels were positively correlated with the percentage of platelet-adherent eosinophils. Among these markers, P-selectin expression and plasma sP-selectin levels positively correlated with urinary concentrations of leukotriene E4. Additionally, plasma sP-selectin and sCD40L levels were negatively correlated with lung function. In contrast, platelet activation markers in patients with AERD did not change during the aspirin challenge test. Peripheral platelets were activated more in patients with stable AERD compared with those in patients with stable ATA, patients with idiopathic chronic eosinophilic pneumonia, and control subjects. Platelet activation was involved in cysteinyl leukotriene overproduction and persistent airflow limitations in patients with AERD.

In vitro effect of Hordeum vulgare on the crystallization of calcium oxalate monohydrate (whewellite)

The recommended conservative treatment of hyperoxaluria is mainly based on hyperhydration and ingestion of inhibitors of crystallization. In accordance with this context, the aim of this study was to determine the in vitro effect of Hordeum vulgare on calcium oxalate crystallization oxalo-dependent. The crystallization of calcium oxalate monohydrate in supersaturated aqueous solution at 37 °C, was followed in a model turbidimetric continuous in a closed system. The proposed model is very good reproducibility (CV < 10%), crystallization was monitored continuously in the presence of Hordeum vulgare at different concentrations (0.0625 to 1 g/L). The comparison of turbidimetric parameters, that characterize the growth stage of monohydrated oxalate calcium crystals and observation of the crystals obtained at the end of crystallization into scanning electron microscopy, have been able to demonstrate the inducing effect of Hordeum vulgare to 0.0625 g/L and a slight inhibitory effect at the others concentrations.

Enzymatic Response of the Eucalypt Defoliator Thyrinteina arnobia (Stoll) (Lepidoptera: Geometridae) to a Bis-Benzamidine Proteinase Inhibitor

Ingestion of proteinase inhibitors leads to hyperproduction of digestive proteinases, limiting the bioavailability of essential amino acids for protein synthesis, which affects insect growth and development. However, the effects of proteinase inhibitors on digestive enzymes can lead to an adaptive response by the insect. In here, we assessed the biochemical response of midgut proteinases from the eucalypt defoliator Thyrinteina arnobia (Stoll) to different concentrations of berenil, a bis-benzamidine proteinase inhibitor, on eucalyptus. Eucalyptus leaves were immersed in berenil solutions at different concentrations and fed to larvae of T. arnobia. Mortality was assessed daily. The proteolytic activity in the midgut of T. arnobia was assessed after feeding on plants sprayed with aqueous solutions of berenil, fed to fifth instars of T. arnobia for 48 h before midgut removal for enzymatic assays. Larvae of T. arnobia were able to overcome the effects of the lowest berenil concentrations by increasing their trypsin-like activity, but not as berenil concentration increased, despite the fact that the highest berenil concentration resulted in overproduction of trypsin-like proteinases. Berenil also prevented the increase of the cysteine proteinases activity in response to trypsin inhibition.

Toxicological effects of red wine, orange juice, and other dietary SULT1A inhibitors via excess catecholamines

SULT1A enzymes protect humans from catecholamines, but natural substances in many foods have been found to inhibit these enzymes in vitro. Given the hormonal roles of catecholamines, any in vivo SULT1A inhibition could have serious consequences. This paper uses a re-analysis of published data to confirm that SULT1A inhibitors have effect in vivo in at least some patients. Nineteen studies are cited that show ingestion of SULT1A inhibitors leading to catecholamine increases, blood pressure changes, migraine headaches, or atrial fibrillation. SULT1A inhibition does not create the catecholamines, but prevents normal catecholamine deactivation. Susceptible patients probably have lower-activity SULT1A alleles. The paper discusses new hypotheses that SULT1A inhibition can cause “holiday heart” arrhythmias and type 2 diabetes in susceptible patients. Subgroup analysis based on SULT1A alleles, and addition of a catecholamine source, should improve the consistency of results from tests of SULT1A inhibitors. SULT1A inhibition may be a key contributor to cheese-induced migraines (via annatto), false positives in metanephrine testing, and the cardiovascular impacts of recreational alcohols.

Prenatal closure of the ductus arteriosus and maternal ingestion of anthocyanins

Prenatal closure of the ductus arteriosus (DA) is associated with maternal ingestion of cyclooxygenase inhibitors during pregnancy. We report a case of prenatal DA closure after maternal ingestion of MonaVie, a juice blend containing the cyclooxygenase and nitric oxide synthase inhibitors anthocyanins and proanthocyanidins. A G(2)P(0)Ab(1) woman had an uncomplicated first and second trimester and normal 20-week fetal ultrasound. At 37 weeks, she developed polyhydramnios; a fetal echocardiogram showed right atrial and ventricular (RV) enlargement with RV dysfunction. Immediately after birth, there was pulmonary hypertension by echocardiogram with DA closure, severe RV hypertrophy and dysfunction, and marked right-to-left atrial shunting. Improvement occurred over 3 weeks with the neonate tolerating room air and a follow-up echocardiogram showing minimal atrial shunting and improved RV function. This report shows an association between MonaVie ingestion throughout pregnancy and prenatal DA closure resulting in cardiac dysfunction and pulmonary hypertension at birth.

Sildenafil- and tadalafil-associated optic neuropathy: implications for men after prostate cancer treatment

The phosphodiesterase 5 (PDE5)-selective inhibitors sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra) are frequently prescribed for treatment of erectile dysfunction (ED). 1 These medications have implications for men with prostate cancer who undergo treatment with radical prostatectomy or radiation therapy (brachytherapy or external beam radiation), as these treatments are associated with an increased risk for ED. Instances of nonarteritic ischemic optic neuropathy (NAION) and permanent vision loss following ingestion of PDE5-selective inhibitors have been reported.2 – 4 Investigators affiliated with the Research on Adverse Drug Events and Reports (RADAR), an established pharmacovigilance program, reviewed the literature as well as US Food and Drug Administration (FDA) reports to determine the frequency and clinical characteristics of PDE5selective inhibitor-associated NAION and permanent vision loss in men with ED. Reports and associated toxicities We reviewed case descriptions of PDE5-selective inhibitor-associated optic neuropathy events reported to the FDA between 1998 and 2004 or in the peer-reviewed literature between 1998 and 2005. Thirty-nine cases of optic neuropathy in sildenafil- or tadalafil-treated patients were identified as case reports (n = 18) or in FDA databases (n = 21). Affected men were similar in age (median, 62 years), and 90% of the cases were reported among men who had ingested PDE5-selective inhibitors and suffered permanent vision loss. Importantly, the quality of the case reports in the FDA database is suboptimal given that they often lack important information on duration of PDE5-selective inhibitor use, time since ingestion of the most recent dose, identification of affected eye, fundoscopic examination findings, and response to de-challenge. A plausible explanation as to cause-and-effect relative to PDE5-selective inhibitor therapy and NAION does not exist.

DISCREPANCY BETWEEN PANCREATIC PROTEIN SECRETION AND CCK RELEASE IN RESPONSE TO BILE-PANCREATIC JUICE DIVERSION IN THE HYPERTROPHIED RAT PANCREAS INDUCED BY SYNTHETIC TRYPSIN INHIBITOR

Pancreatic exocrine secretion in conscious rats is mainly regulated by protease activities in the proximal intestine (luminal feedback regulation).1 Decrease in protease activities by ingestion of trypsin inhibitors (TI)s or diversion of bile-pancreatic juice (BPJ) stimulates pancreatic secretion2 and produces pancreatic hypertrophy via CCK release. Since CCK releasing factor, LCRF was purified from rat intestine,3 we determined whether the levels of LCRF, CCK, and protein secretion were synchronized to one another. Changes in pancreatic secretion, plasma CCK levels, and luminal LCRF contents produced by 2- and 4-h BPJ diversion, were determined in rats with 7-day TI treatment, and compared with controls. A diet containing 0.1% synthetic TI (ONO-3402) and a standard diet (CE-2) were fed in Wistar male rats for 7 days. After 7 day-treatment, the pancreatic wet weight was significantly higher in TI treated rats than the controls. For the experiments, on the third day of the feeding, rats were prepared with cannulas draining BPJ separately, and with a duodenal cannula and with an external jugular vein cannula. On the 7th day of the feeding, after 90 min of basal secretion with returning BPJ, BPJ were diverted. Changes in pancreatic secretions of fluid and protein were determined. After 2- and 4-h BPJ diversion, rats were sacrificed. Samples of 3-4 ml of blood were withdrawn through the venous cannula to measure plasma CCK concentrations. The proximal quarter of the small intestine was removed to measure LCRF content. The levels of LCRF and CCK were parallel (Fig. 1). Pancreatic protein secretion was higher in rats treated with TI than in controls throughout the experimental period. The plasma CCK and luminal LCRF content 4-h after BPJD was significantly lower in rats treated with TI than in controls. The hypertrophied pancreas may require a smaller dose of CCK to increase protein secretion.FIGURE 1: Changes in plasma CCK concentrations, LCRF content, and pancreatic protein secretion after 4-h BPJ diversion. *significantly different from the control values. TI; trypsin inhibitor. The numbers in the parentheses are the number of animals.

Unintentional paediatric ingestions of angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists

There is limited information on safety of angiotensin converting enzyme (ACE) inhibitors and angiotensin II (AII) receptor antagonists in unintentional paediatric ingestions. This study was conducted with the aim of developing referral guidelines for poison information centres. Calls to the NSW poison information centre from January 2002 to July 2004 regarding paediatric ingestion of ACE inhibitors and AII receptor antagonists were recruited and prospectively followed up. Information collected included: demographics (age, gender, weight), type of exposure (unintentional, therapeutic error), ingested dose and clinical effects. Dose was reported in defined daily doses (DDD) to compare across and within the two drug classes with respect to the normal adult dose. Nineteen cases of paediatric ingestion of ACE inhibitors and AII receptor antagonists were included. The median age was 2 years (Interquartile range (IQR): 20-33 months) and the median dose ingested was 1 DDD (IQR: 1-2). There were nine ACE inhibitor ingestions and 10 AII receptor antagonist ingestions. One of nine children (11%) observed in hospital developed transient hypotension but required no treatment and recovered without complication. This child ingested an ACE inhibitor and ingested >3 DDD. Unintentional paediatric ingestions of ACE inhibitors and AII receptor antagonists resulted in the majority of children remaining asymptomatic. ACE inhibitor ingestions under 2 DDD can be observed at home provided the child is asymptomatic and there is a responsible adult to observe the child. The dose required for observation in AII receptor antagonist ingestions is less clear.

Cortisol metabolism in hypertension

Corticosteroids are critically involved in blood pressure regulation. Lack of adrenal steroids in Addison's disease causes life-threatening hypotension, whereas glucocorticoid excess in Cushing's syndrome invariably results in high blood pressure. At a pre-receptor level, glucocorticoid action is modulated by 11beta-hydroxysteroid dehydrogenases (11beta-HSDs). 11Beta-HSD1 activates cortisone to cortisol to facilitate glucocorticoid receptor (GR)-mediated action. By contrast, 11beta-HSD2 plays a pivotal role in aldosterone target tissues where it catalyses the opposite reaction (i.e. inactivation of cortisol to cortisone) to prevent activation of the mineralocorticoid receptor (MR) by cortisol. Mutations in the 11beta-HSD2 gene cause a rare form of inherited hypertension, the syndrome of apparent mineralocorticoid excess (AME), in which cortisol activates the MR resulting in severe hypertension and hypokalemia. Ingestion of competitive inhibitors of 11beta-HSD2 such as liquorice and carbenoxolone result in a similar but milder clinical phenotype. Epidemiological data suggests that polymorphic variability in the HSD11B2 gene determines salt sensitivity in the general population, which is a key predisposing factor to adult onset hypertension in some patients. Extrarenal sites of glucocorticoid action and metabolism that might impact on blood pressure include the vasculature and the central nervous system. Intriguingly, increased exposure to glucocorticoids during fetal life promotes high blood pressure in adulthood suggesting an early programming effect. Thus, metabolism and action in many peripheral tissues might contribute to the pathophysiology of human hypertension.

Quel est l’impact des complications cardiovasculaires et rénales sur le rapport bénéfice/risque digestif des AINS?

Long-term studies of NSAIDs have demonstrated cardiovascular toxicity which poses a general problem of the benefit risk between the relief of the patient's symptoms and the risk of digestive and cardiovascular toxicity. The digestive complications and the risk factors associated with the ingestion of NSAIDs have been defined by numerous studies but the prevention of this digestive toxicity can be attempted. The benefit-risk ratio caused by the digestive and cardiovascular toxicities of the NSAIDs and COX-2 inhibitors must be evaluated for each individual before starting a treatment. For a treatment of short duration in patients with a low risk of digestive and cardiovascular complications, the risk of digestive toxicity must be taken into consideration first and the COX-2 inhibitors are favoured. For a treatment of long duration the risk must be evaluated with the greatest care. In the case of cardiovascular risk factors, the cardiovascular risk must be evaluated and the treatment must be prescribed at the lowest dose for the shortest duration. In patients with very high risk of digestive and cardiovascular complications, since the digestive and cardiovascular extra-mortality associated with the ingestion of NSAIDs or COX-2 inhibitors is high, it is advised to abandon this type of long-term treatment.

Structural basis of the resistance of an insect carboxypeptidase to plant protease inhibitors

Corn earworm (Helicoverpa zea), also called tomato fruitworm, is a common pest of many Solanaceous plants. This insect is known to adapt to the ingestion of plant serine protease inhibitors by using digestive proteases that are insensitive to inhibition. We have now identified a B-type carboxypeptidase of H. zea (CPBHz) insensitive to potato carboxypeptidase inhibitor (PCI) in corn earworm. To elucidate the structural features leading to the adaptation of the insect enzyme, the crystal structure of the recombinant CPBHz protein was determined by x-ray diffraction. CPBHz is a member of the A/B subfamily of metallocarboxypeptidases, which displays the characteristic metallocarboxypeptidase alpha/beta-hydrolase fold, and does not differ essentially from the previously described Helicoverpa armigera CPA, which is very sensitive to PCI. The data provide structural insight into several functional properties of CPBHz. The high selectivity shown by CPBHz for C-terminal lysine residues is due to residue changes in the S1' substrate specificity pocket that render it unable to accommodate the side chain of an arginine. The insensitivity of CPBHz to plant inhibitors is explained by the exceptional positioning of two of the main regions that stabilize other carboxypeptidase-PCI complexes, the beta8-alpha9 loop, and alpha7 together with the alpha7-alpha8 loop. The rearrangement of these two regions leads to a displacement of the active-site entrance that impairs the proper interaction with PCI. This report explains a crystal structure of an insect protease and its adaptation to defensive plant protease inhibitors.

Coupling diet quality and Bowman‐Birk and Kunitz‐type soybean proteinase inhibitor effectiveness to Diatraea saccharalis development and mortality

AbstractWe used bioassays to investigate the effect of Bowman‐Birk and Kunitz‐type soybean proteinase inhibitors on two artificial diets (diets 1 and 2) which are commonly used to feed laboratory colonies of larvae of the moth Diatraea saccharalis, monitoring food intake and utilization, and larval development and mortality. Diet 1 was less nutritious, with a low protein content and reduced mineral and essential amino acid (e.g., cysteine, lysine, and methionine) content, while diet 2 was richer and more complete. When proteinase inhibitors were incorporated into the artificial diets, the effects on larval development were significantly greater for those larvae fed diet 1, with the chronic ingestion of proteinase inhibitors reducing the level of trypsin‐like activity in the midgut of larvae fed this diet. Larvae fed diet 2 also showed a reduced level of tryptic activity in the midgut, but this was less marked than for diet 1. These results indicate that despite their inhibitory effect on midgut enzymes, the effectiveness of proteinase inhibitors is directly dependent on the quality of the diet. The different effects seen on insect biology when proteinase inhibitors are added to rich or poor diets suggests that the role of anti‐nutritional proteins in the control of insects might not be adequately addressed by bioassays based on the incorporation of inhibitors into artificial diets.

Identification of six chymotrypsin cDNAs from larval midguts of Helicoverpa zea and Agrotis ipsilon feeding on the soybean (Kunitz) trypsin inhibitor

Lepidopteran insects like Helicoverpa zea and Agrotis ipsilon produce STI-insensitive trypsins in the midgut following ingestion of dietary plant proteinase inhibitors like STI [ Broadway, R. M., J. Insect Physiol. 43(9) (1997) 855–874]. In this paper, the effects of dietary STI on a related family of midgut serine proteinases, the chymotrypsins, were investigated. STI-insensitive midgut chymotrypsins were detected in larvae of H. zea and A. ipsilon feeding on diets containing 1% STI while STI-sensitive chymotrypsins were present in larvae feeding on diets containing 0% STI. These chymotrypsins were unaffected by TPCK, a diagnostic inhibitor of mammalian chymotrypsins but were fully inhibited by chymostatin. Four midgut cDNA libraries were constructed from larvae of each species fed either 0% STI or 1% STI diets. Six full-length cDNAs 1 GenBank Accessions # AF233728-AF233737 1 encoding diverse preprochymotrypsins were isolated (three from H. zea and three from A. ipsilon) with certain sequence motifs that set them apart from their mammalian counterparts. Northern blots showed that some chymotrypsin mRNA were detected at higher levels while others were down-regulated when comparing insects reared on 0% STI and 1% STI diets. Southern hybridizations suggested that (like mammals) both species contained several chymotrypsin genes. A full-length chymotrypsin gene 1 from H. zea was sequenced for the first time and the presence of four introns was deduced. A first time comparison of 5′ upstream regions 1 from three chymotrypsin genes and two trypsin genes of A. ipsilon indicated the presence of putative TATA boxes and regulatory elements. However a lack of consensus motifs in these upstream regions suggested the likelihood of multiple trans factors for regulation of genes encoding digestive proteinases and a complex response mechanism linked to ingestion of proteinase inhibitors.

Influence of a Cysteine Proteinase Inhibitor on Alfalfa Weevil (Coleoptera: Curculionidae) Growth and Development Over Successive Generations

The influence of leupeptin, a cysteine and serine proteinase inhibitor, on alfalfa weevil, Hypera postica (Gyllenhal), growth and development was investigated over nine successive generations. Concern that ingestion of proteinase inhibitors by phytophagous insects could induce production of inhibitor-insensitive proteinase activity initiated this investigation. The percent alfalfa weevil larval, pupal and adult survival, and defoliation was significantly lower on alfalfa foliage treated with leupeptin than on untreated foliage in all nine generations tested. Main effects for generations and treatment times generation were nonsignificant for all variables. This study demonstrates that after nine generations leupeptin, when compared to an untreated control, does not lose its ability to significantly inhibit alfalfa weevil growth and development. This suggests that the alfalfa weevil did not utilize or induce other proteinases (digestive enzymes) to compensate for inhibition of one of its major proteinases.