[On protease inhibitors. I. Isolation and characterization of trypsin inhibitors from dog pancreas tissue and pancreas scretion]

Usefulness of Selected Acute-Phase Proteins in the Postsurgical Monitoring of Arthroscopy and Splint Bone Removal in Horses

Simple Summary

The study shows the changes in concentration of acute phase proteins (fibrinogen, haptoglobin, protease inhibitors) in the serum of patients from the equine clinic. Blood was collected from horses that underwent arthroscopy (41 horses) and splint bone removal (13 horses). The concentration of the above-mentioned proteins was recorded from the time before the surgery until the 28th day after the surgery and compared to a control group of healthy horses (60 horses). Acute phase proteins change their concentration before clinical symptoms appear; therefore, they could play a key role in early recognition and preventing complications.

Abstract

Background: Arthroscopy and splint bone removal are the common orthopedic procedures in horses. Estimation of the dynamics of acute phase proteins in postoperative monitoring seems to be interesting diagnostic approach. The aim of the study was to investigate changes in the concentrations of plasma inflammatory markers—fibrinogen, haptoglobin, and protease inhibitors—following orthopedic surgery in horses. The study involved 114 horses, divided into two study groups undergoing: arthroscopy (41 horses) and splint bone removal (13 horses). The control group consisted of 60 healthy horses. The blood was collected before the surgery and 24, 48, 72 h, 5, 7, 10, 14 and 28 days after the surgery. Plasma fibrinogen, serum haptoglobin and proteinase inhibitors were measured. Results: In non-complicated cases of arthroscopy and splint bone removal, fibrinogen and haptoglobin increased stepwise from 24 h, achieved the maximum level at 72 h and returned to preoperative levels after 10–14 days. In one complicated case after arthroscopy surgery the marked increase in fibrinogen and haptoglobin concentrations was observed 24 h earlier than standard parameters of inflammation Conclusion: The study shows the evolution of APPs after arthroscopy and splint bone removal in 28 days postsurgery period and in the case of one complicated case of arthroscopy.

Exocrine Pancreatic Maturation in Pre-term and Term Piglets Supplemented With Bovine Colostrum

Pre-term infants have an immature digestive system predisposing to short- and long-term complications including feeding intolerance, maldigestion and necrotizing enterocolitis (NEC). Optimal feeding strategies are required to promote maturation of the gut including the exocrine pancreas. Little is known about age- and diet-related development of pancreatic exocrine enzymes following pre-term birth. Currently, bovine colostrum supplementation is investigated in clinical trials on pre-term infants. Using pigs as models for infants, we hypothesized that pancreatic enzyme content is (1) immature following pre-term birth, (2) stimulated by early colostrum supplementation, and (3) stimulated by later colostrum fortification. Thus, using piglets as models for infants, we measured trypsin, amylase, lipase and total protein in pancreatic tissue collected from piglets delivered by cesarean section either pre-term (90% gestation) or close to term. Experiment 1:Pre-term and term pigs were compared at birth and 11 days. Experiment 2: Pre-term and term pigs were either enterally supplemented with bovine colostrum or fed total parenteral nutrition for 5 days, followed by exclusive milk feeding until day 26. Experiment 3: Pre-term pigs were fed bovine's milk with or without colostrum fortification until 19 days. The results showed that pancreatic trypsin, amylase and total protein contents were reduced in pre-term vs. term pigs. Trypsin mainly increased with advancing post-conceptional age (2-fold), while amylase was affected predominantly by advancing post-natal age, and mostly in pre-term pigs from birth to 11 or 26 days. Colostrum feeding in both term and pre-term piglets decreased trypsin and increased amylase contents. Lipase activity decreased with advancing gestational age at birth and post-natal age, with no consistent responses to colostrum feeding, with lipase activities decreasing relative to total pancreatic protein content. In summary, key pancreatic enzymes, amylase and trypsin, are immature following pre-term birth, potentially contributing to reduced digestive capacity in pre-term neonates. Rapid post-natal increases occurs within few weeks of pre-term birth, partly stimulated by enteral colostrum intake, reflecting a marked adaptation capacity. Alternatively, lipase is less affected by pre-/post-natal age and feeding. Thus, there is a highly enzyme-specific and asymmetric perinatal development of the exocrine pancreas.

Early effects on the intestinal barrier and pancreatic function after enteral stimulation with protease or kidney bean lectin in neonatal rats

Gut maturation naturally accelerates at weaning in altricial mammalian species, such as the rat. Mimicking this, gut development can also be induced precociously, 3-4 d earlier than it would occur naturally, by enteral exposure to phytohaemagglutinin (PHA), or various proteases. We investigated the early effects of gut provocation on intestinal barrier and pancreatic functions, to get a better understanding of the mechanisms that initiate gut maturation. The effects of oral administration of protease (trypsin) or PHA to 14-d-old suckling rats were studied during 24 h in comparison with water-fed controls. Intestinal in vivo permeability was assessed by oral administration of different-sized marker molecules and measuring their passage into the blood or urine 3 h later. A period of 24 h following oral administration, both PHA and protease provocation stimulated small intestinal (SI) growth and pancreatic secretion, as indicated by decreased pancreatic trypsin and increased luminal enzyme content. Within 1 h of oral administration, both treatments prevented the absorption of macromolecules to blood that was observed in controls. PHA treatment hindered the passage of fluorescein isothiocyanate-dextran (FD) 4 to blood, whereas protease treatment temporarily increased plasma levels of FD4, and the urine lactulose:mannitol ratio, indicating increased intestinal leakiness. Following protease treatment, fluorescence microscopy showed decreased vesicular uptake of FD70 in the proximal SI and increased epithelial fluorescence in the distal SI. In conclusion, PHA and protease differed in their early effects on the intestinal barrier; both exerted a blocking effect on epithelial endocytosis, whereas protease treatment alone temporarily increased epithelial leakiness, which seemed to be confined to the distal SI.

Induction of precocious intestinal maturation in T-cell deficient athymic neonatal rats

AIM

To investigate whether gut maturation could be induced precociously in an athymic T-cell deficient neonatal rat model.

METHODS

Fourteen day-old athymic (nude) rats (NIH-Foxn1^rnu) were gavaged with either phytohaemagglutinin - a lectin from red kidney beans (PHA); trypsin - a protease (Prot); or water - vehicle (control) as a single dose on one day or once a day for 3-day. The nude rats were either nurtured by their mothers or cross-fostered by conventional foster dams of the Sprague-Dawley strain from days 3-5 after birth. At 17 d of age, 72 h after administration of the first treatment, intestinal macromolecular permeability was tested in vivo, prior to euthanasia, after which blood and gut organs were sampled.

RESULTS

Provocation with both, PHA and protease, resulted in increased gut growth and maturation in nude rat pups independent of nursing. Foetal-type enterocytes were replaced by non-vacuolated adult-type enterocytes in the distal small intestine epithelium. Decreased intestinal macromolecular permeability (gut closure) was observed, with reduced permeability markers (BIgG and BSA, P < 0.001) in circulation. Increased pancreatic function, with an increased trypsin to protein ratio in pancreas homogenates, was observed independent of nursing in the nude pups. Immunostaining showed the presence of a few CD3⁺-cells in the intestinal mucosa of the nude pups. The number of CD3⁺-cells remained unaltered by provocation and no differences were observed between the nursing sets. Growth and vitality of the nude pups were dependent on nurturing, since cross-fostering by conventional dams increased their macromolecular absorptive capacity (BSA, P < 0.05), as well as their passive immunity (RIgG, P < 0.05).

CONCLUSION

Precocious gut maturation can be induced by enteral provocation in athymic rat pups, similarly to in euthymic pups, thus showing an independence from thymus-derived T-cells.

Purification and characterization of a newly serine protease inhibitor from Rhamnus frangula with potential for use as therapeutic drug

Protease inhibitors from plants are well known to be potent inhibitors of the growth of bacteria, fungi, and even certain viruses which make them excellent candidates for use as the lead compounds for the development of novel antimicrobial agents for applications in medicine. In this study, Rhamnus frangula was selected as a protease inhibitor source. The maximum recovery of the protease inhibitor against trypsin was recorded in the crude extract made in 0.1 M phosphate buffer (pH 7.0) and isolated from the mature leaves. Then, the protease inhibitor designated as RfIP1 was purified to homogeneity by Sephadex G50 with an apparent molecular mass of 22.5 kDa and its N-terminal sequence exhibited a high degree of homology with known serine protease inhibitor sequences. The RfIP1 displayed maximal activity at pH 7 and 37 °C. It maintained almost 80% of its maximal activity through a large pH range. The thermo-stability of RfIP1 was markedly enhanced by BSA, CaCl2, and sorbitol, whereas the addition of Mg2+, Zn2+, NaTDC, SDS, DTT, and β-ME significantly promoted inhibitory activity. The protease inhibitor displayed high inhibitory activity toward some known proteases (cathepsin B, chymotrypsin, collagenase, thrombin, and trypsin) that have more importance in pharmaceutical industry and it acted as potent inhibitor of some commercially proteases from Aspergillus oryzae, Bacillus sp, and Bacillus licheniformis. The protease inhibitor also possessed an appreciable antibacterial effect against both Gram-positive and Gram-negative bacteria.

Boronic Acid-Appended Molecular Glues for ATP-Responsive Activity Modulation of Enzymes

Water-soluble linear polymers GumBAn (m/n = 18/6, 12/12, and 6/18) with multiple guanidinium ion (Gu(+)) and boronic acid (BA) pendants in their side chains were synthesized as ATP-responsive modulators for enzyme activity. GumBAn polymers strongly bind to the phosphate ion (PO4(-)) and 1,2-diol units of ATP via the Gu(+) and BA pendants, respectively. As only the Gu(+) pendants can be used for proteins, GumBAn is able to modulate the activity of enzymes in response to ATP. As a proof-of-concept study, we demonstrated that trypsin (Trp) can be deactivated by hybridization with GumBAn. However, upon addition of ATP, Trp was liberated to retrieve its hydrolytic activity due to a higher preference of GumBAn toward ATP than Trp. This event occurred in a much lower range of [ATP] than reported examples. Under cellular conditions, the hydrolytic activity of Trp was likewise modulated.

Protease inhibitor from Moringa oleifera with potential for use as therapeutic drug and as seafood preservative

Protease inhibitors are well known to have several applications in medicine and biotechnology. Several plant sources are known to return potential protease inhibitors. In this study plants belonging to different families of Leguminosae, Malvaceae, Rutaceae, Graminae and Moringaceae were screened for the protease inhibitor. Among them Moringa oleifera, belonging to the family Moringaceae, recorded high level of protease inhibitor activity after ammonium sulfate fractionation. M. oleifera, which grows throughout most of the tropics and having several industrial and medicinal uses, was selected as a source of protease inhibitor since so far no reports were made on isolation of the protease inhibitor. Among the different parts of M. oleifera tested, the crude extract isolated from the mature leaves and seeds showed the highest level of inhibition against trypsin. Among the various extraction media evaluated, the crude extract prepared in phosphate buffer showed maximum recovery of the protease inhibitor. The protease inhibitor recorded high inhibitory activity toward the serine proteases thrombin, elastase, chymotrypsin and the cysteine proteases cathepsin B and papain which have more importance in pharmaceutical industry. The protease inhibitor also showed complete inhibition of activities of the commercially available proteases of Bacillus licheniformis and Aspergillus oryzae. However, inhibitory activities toward subtilisin, esperase, pronase E and proteinase K were negligible. Further, it was found that the protease inhibitor could prevent proteolysis in a commercially valuable shrimp Penaeus monodon during storage indicating the scope for its application as a seafood preservative. This is the first report on isolation of a protease inhibitor from M. oleifera.

Immune suppression by cyclosporin A inhibits phytohemagglutinin-induced precocious gut maturation in suckling rats

OBJECTIVES

Enteral exposure to the lectin phytohemagglutinin (PHA) provokes precocious gut maturation in suckling rats coinciding with an early expansion of intestinal mucosal T and B lymphocytes. Here, the role of the immune system in neonatal gut growth and maturation was further studied.

MATERIALS AND METHODS

The effects of immunosuppression by cyclosporine A (CyA), 7.5 microg/g of body weight, injected 12 hours before and then daily after the intragastric gavage of PHA, 100 microg/g body weight, to 14-day-old suckling rats were studied after 4 and 12 hours and later after 72 hours.

RESULTS

At 4 hours after PHA feeding, an early rapid increase in the intestinal levels of the proinflammatory cytokines interleukin-6, interleukin-1beta, and tumor necrosis factor was obtained, and the CyA treatment did not prevent the temporary PHA-induced intestinal disturbance seen at 12 hours. Later, at 72 hours after PHA gavage the CyA treatment significantly counteracted the PHA-induced gut changes with a decrease in small intestinal growth, a delay in the appearance of adult-phenotype enterocytes in the distal small intestinal, and total inhibition of the PHA-induced pancreas development. Additionally, the increase in plasma level of the acute phase protein, haptoglobin, after PHA feeding was dampened by CyA.

CONCLUSIONS

The results indicate that proinflammatory cytokines are involved in the early recruitment of lymphocytes to the gut after PHA challenge, and that the ensuing precocious gut maturation is dependent on activation of the immune system, presumably T cells, in suckling rats.

Age-related effects of the probiotic bacterium Lactobacillus plantarum 299v on gastrointestinal function in suckling rats

The effect of a probiotic bacterium on gut function was studied in neonatal animals by using a model with suckling rats. Lactobacillus plantarum 299v (Lp299v) or saline (controls) was fed (3.0 x 10(6) CFU/g b.wt per day) for one week to rats aged either 3, 7 or 14 days, after which bacterial colonization, gut growth, and functional parameters were analyzed. In rats fed with Lp299v from 3 to 10 days of age, an increase in ceacal lactobacilli was correlated with reduced intestinal macromolecular permeability and increased mucosal protein compared to age-matched controls. Pups treated from 7 to 14 days of age showed a decrease in pancreas weight and protein content, whereas pups treated from 14 to 21 days of age showed little effect of the Lp299v treatment. The results indicated that the bacterial exposure affected the gut function, where the effects were age-related and the youngest rats appeared most sensitive.

Maternal consumption of Lactobacillus plantarum 299v affects gastrointestinal growth and function in the suckling rat

After birth, the gastrointestinal (GI) tract undergoes vast structural and functional adaptations to be able to digest mother's milk and later, during the weaning period, solid food. Studies on germ-free animals have shown the role of the gut microbiota for stimulating GI maturation, but which groups are involved is unclear. In the present study, we administered the probiotic bacterium, Lactobacillus plantarum 299v (Lp299v), in the drinking water to pregnant and lactating rat dams until their pups had reached an age of 14 d. It was found that Lp299v colonizing the mothers were also able to colonize the pups, which had an impact on their gut growth and function. The small intestine, pancreas and liver weighed more in the 14 d-old pups born from dams exposed to Lp299v than in the control pups from dams given only water. Furthermore, the Lp299v pups showed decreased gut permeability. Despite a heavier spleen in the Lp299v pups, as compared to the control pups, no significant increase in the acute-phase protein, haptoglobin, was found. In conclusion, the results reported here clearly show that manipulating the maternal microflora by exposing expecting mothers to a Gram-positive, probiotic bacterium prior to parturition and during lactation impacts the gut growth and function in the offspring.

Microbial manipulation of the rat dam changes bacterial colonization and alters properties of the gut in her offspring

The impact of an altered bacterial colonization on gut development has not been thoroughly studied, despite the increased risk of certain diseases with a disturbed microbiota after birth. This study was conducted to determine the effect of microbial manipulation, i.e., antibiotic treatment or Escherichia coli exposure, of the dam on bacterial colonization and gut development in the offspring. Pregnant rats were administered either broad-spectrum antibiotics 3 days before parturition or live nonpathogenic E. coli Culture Collection of University of Göteborg, Sweden type strain (CCUG 29300(T)) 1 wk before parturition and up to 14 days of lactation in the drinking water. Cecal bacterial levels, gut growth, intestinal permeability, digestive enzyme levels, and intestinal inflammation were studied in 2-wk-old rats. Pups from dams that were antibiotic-treated had higher densities of Enterobacteriaceae, which correlated with a decreased stomach growth and function, lower pancreatic protein levels, higher intestinal permeability, and increased plasma levels of the acute phase protein, haptoglobin, compared with pups from untreated mothers. Exposure of pregnant/lactating mothers to E. coli CCUG 29300(T), also resulting in increased Enterobacteriaceae levels, gave in the offspring similar results on the stomach and an increased small intestinal growth compared with the control pups. Furthermore, E. coli pups showed increased mucosal disaccharidase activities, increased liver, spleen, and adrenal weights, as well as increased plasma concentrations of haptoglobin. These findings indicate that disturbing the normal bacterial colonization after birth, by increasing the densities of cecal Enterobacteriaceae, appears to have lasting effects on the postnatal microflora, which affects gut growth and function.

Binding and the effect of the red kidney bean lectin, phytohaemagglutinin, in the gastrointestinal tract of suckling rats

Enteral exposure of suckling rats to phytohaemagglutinin (PHA) has been shown to induce growth and precocious functional maturation of the gastrointestinal tract. The aim of the present study was to explore the mechanism of this action. Suckling rats, 14d old, were fed a single dose of PHA (0·05mg/g body weight) or saline. The binding of PHA to the gut epithelium and its effect on the morphology and functional properties of the gut and pancreas were studied up to 3d after treatment. Initially, at 1–24h, the PHA bound along the gut mucosal lining, resulting in disturbed gut morphology with villi shortening and rapid decreases in disaccharidase activities and macromolecular absorption capacity. During a later phase, between 1 and 3d, the PHA binding had declined, and an uptake by enterocytes was observed. An increase in crypt cell proliferation and gut growth became evident during this period, together with a functional maturation, as indicated by increases in disaccharidase (maltase and sucrase) activities and the low macromolecular absorption capacity. Pancreas growth also increased, as did its content of digestive enzymes. We conclude that enteral exposure to PHA in suckling rats temporarily causes mucosal disarrangement and functional impediment of the gut, which may be explained by binding to and disruption of the gut mucosa and a two-fold increase in the plasma corticosterone concentration. These findings may lead to a better understanding of the role of diet in gastrointestinal maturation and may constitute a basis for the treatment of mammals having an immature gut.

Effects of crude red kidney bean lectin (phytohemagglutinin) exposure on performance, health, feeding behavior, and gut maturation of pigs at weaning1

The aim of this study was to obtain information that could help to ease the weaning transition in commercial pig production. Before weaning, phytohemagglutinin (PHA) in the form of a crude preparation of red kidney bean lectin was fed by gavage to 24 crossbred [(Swedish Landrace x Yorkshire) x Hampshire] piglets, whereas 24 control piglets were fed alpha-lactalbumin by gavage, to study the effect on growth, occurrence of postweaning diarrhea, feeding behavior, and some anatomical and physiological traits of the gastrointestinal tract. Within the litter, piglets were randomly assigned to PHA treatment or control and remained in the same pen from the beginning (PHA exposure at 7 d before weaning) until the end of the experiment (14 d post-weaning). Weaning took place at the age of 31 to 34 d. Pigs treated with PHA grew faster (P = 0.013) during the first week postweaning and tended to have lower total diarrhea scores (P = 0.10) than did control pigs. On d 5 after weaning, piglets treated with PHA spent more time eating (P = 0.028) than control pigs. No immunostimulating effect of PHA, measured by plasma immunoglobulin G, could be detected. An increase in the intestinal barrier properties before weaning, as a response to PHA treatment, was demonstrated in intestinal absorption studies using Na-fluorescein and BSA as gavage-fed markers. Less uptake (measured as plasma concentrations) of the marker molecule Na-fluorescein occurred during a 24-h study period, and numerically lower levels of BSA were observed compared with studies in control pigs of the same age. A total of 12 pigs (6 control, 6 PHA-treated) were euthanized on the day of weaning for analyses of gastrointestinal properties. The PHA-treated pigs tended to have a longer total small intestinal length (P = 0.063) than that of the control pigs. The enzyme profile of the jejunal epithelium responded to PHA exposure with a decrease in lactase activity and an increase in maltase and sucrase activities, which is similar to changes normally observed after weaning. No differences were found in the size of the pancreas or in its contents of trypsin and amylase. In conclusion, exposing piglets to crude, red kidney bean lectin for 3 d during the week before weaning led to changes in performance and small intestinal functional properties that would be expected to contribute to a more successful weaning.

Enterally but Not Parenterally Administered Phaseolus vulgaris Lectin Induces Growth and Precocious Maturation of the Gut in Suckling Rats

BACKGROUND

The lectin, phytohemagglutinin (PHA) has been shown to induce growth and functional maturation of the gastrointestinal (GI) tract in suckling rats.

OBJECTIVES

To investigate the effect of the administration route, and whether enteral exposure to PHA was necessary to induce functional maturation.

METHODS

Fourteen-day-old rats were daily administered PHA via orogastric feeding (0.05 mg PHA/g BW) or via subcutaneous injection (0.05 or 0.005 mg PHA/g BW) for 3 days, while the controls received saline orogastrically. At 17 days of age, organ weight, intestinal and pancreatic function, and plasma corticosterone levels were analyzed. Moreover, 14-days old pups receiving a single dose of PHA, enterally or parenterally, were sacrificed after 12 h and examined for organ PHA binding using immunohistochemistry.

RESULTS

Enteral PHA exposure resulted in PHA binding in the epithelial lining of the small intestine, increased gastrointestinal growth, reduced intestinal macromolecular absorption, altered the disaccharidase expression towards an adult-like pattern, and increased the pancreatic protein and trypsin contents. In contrast, parenteral PHA exposure (high dose) resulted in PHA-binding in extra-intestinal organs, increased liver and spleen weight, and decreased thymus weight. Moreover, the intestinal maltase activity increased moderately, and the transfer of BSA to blood plasma was partially reduced. Both PHA treatments led to elevated plasma corticosterone levels.

CONCLUSION

These results demonstrated that enteral exposure to PHA was necessary to induce the precocious maturation of the GI tract and the pancreas, while parenteral administration affects the extra-intestinal organs. Furthermore, the enteral effects were probably not mediated via a corticosteroid dependent pathway.

Induced growth and maturation of the gastrointestinal tract after Phaseolus vulgaris lectin exposure in suckling rats

OBJECTIVES

In mammals, the postnatal development of the gastrointestinal tract is characterized by vast structural and functional changes. Using a suckling rat model, we investigated whether red kidney bean lectin, phytohemagglutinin (PHA), a potent gut mitogen in adult rats, can accelerate the growth and maturation of the gastrointestinal tract.

METHODS

At either 10 or 14 days of age, suckling rats were daily gavage fed with PHA (0.05 mg/g body weight) or saline for 3 days. At 1 or 3 days after this treatment, gastrointestinal organ growth, intestinal morphology, disaccharidase pattern, macromolecular absorption capacity, and pancreatic enzyme contents were studied.

RESULTS

After PHA exposure, increased small intestinal growth and number of crypt cells were observed, whereas the proportion of enterocytes with supranuclear vacuoles in the distal intestine was decreased. The macromolecular absorption of the markers bovine immunoglobulin (Ig)G and bovine serum albumin and plasma levels of maternal IgG decreased, and intestinal disaccharidases switched toward an adult-like pattern. The pancreas weight and pancreatic protein and trypsin contents increased. These changes were partly reversible when the PHA treatment began at 10 days of age, but they persisted when the treatment began at 14 days of age.

CONCLUSIONS

PHA induced enhanced growth and precocious functional maturation of the gastrointestinal tract in suckling rats. The effects persisted if the PHA treatment started at 14 days of age, but not before, suggesting an age dependent mechanism. These findings may lead to a better understanding of gastrointestinal maturation and constitute a basis for the treatment of mammals having an immature gut.

Oxidant-mediated proteolytic activation of Ca(+)-ATPase in microsomes of pulmonary smooth muscle

Treatment of bovine pulmonary artery smooth muscle tissue microsomes with H2O2 (1 mM) markedly stimulated protease activity tested with a synthetic substrate N-benzoyl-DL-arginine p-nitroanilide (BAPNA), and also enhanced Ca(2+)-ATPase activity. ATP-dependent Ca(2+) uptake was found to be stimulated upon treatment of the microsomes with H2O2. Pretreatment of the microsomes with vitamin E and aprotinin prevented the H2O2-induced stimulation of Ca(2+)-ATPase activity and also ATP-dependent Ca(2+) uptake. In contrast, H2O2-induced inhibition of Na(+)-dependent Ca(2+) uptake was reversed by vitamin E and aprotinin.

Identification of substrate-analog trypsin inhibitors through the screening of synthetic peptide combinatorial libraries

Synthetic peptide combinatorial libraries (SPCLs), which are made up in total of tens to hundreds of millions of peptides, enable the systematic screening for biologically active peptides in virtually all in vitro and even in vivo assay systems. In the current study, the applicability of this method to the identification of peptide enzyme inhibitors was investigated using trypsin as the model enzyme. A specifically designed library of hexapeptide mixtures was synthesized on cotton carriers and screened. The synthetic approach, using cotton as a solid support, was modified so that the deprotected peptides remained attached to the cotton carrier until they were released into solution directly prior to being assayed. Following an iterative process of synthesis and screening, in which all of the positions of the sequence were successively defined, a number of individual hexapeptides with trypsin inhibitory activity were identified. The most active, defined individual peptide sequence was then reincorporated into a new library, now made up of dodecapeptide mixtures. The iterative screening and synthesis of this library led to a dodecapeptide with improved inhibitory activity when compared to the hexapeptide from which it was derived.

Platelet cationic proteins are present in glomeruli of lupus nephritis patients

Synthetic polycations have been shown to bind and neutralize glomerular polyanions (GPA), thereby increasing the permeability of the glomerular capillary wall (GCW). In the present study it is demonstrated that human platelet-derived cationic proteins (HuPlt CP), which are able to increase cutaneous vascular permeability, bind in vitro to the GCW following incubation of normal human kidney sections with purified HuPlt CP or with washed human platelets stimulated with thrombin, immune complexes (IC) and platelet-activating factor (PAF), or stimulated with a suspension of washed human platelets and polymorphonuclear leukocytes in the presence of phagocytable substrate. The antiserum used in immunofluorescence test to detect the binding of HuPlt CP was specific for two different molecular types of HuPlt CP, both with an isoelectric point (pI) of 10.5. Glomerular deposits of HuPlt CP were also detectable by immunofluorescence microscopy in renal glomeruli present in tissue obtained by biopsy from patients with systemic lupus erythematosus (SLE), a disease in which platelets have been implicated as mediator of glomerular injury. These data indicate that when activated platelets release HuPlt CP in vivo, these proteins bind to glomerular structures. The binding of HuPlt CP to GCW appears to be ionic in nature since heparin, a polyanion, prevents this binding in vitro. In addition, heparin, as well as a high molarity buffer, removed deposits of HuPlt CP bound in vitro to normal GCW or bound in vivo to glomeruli of patients with SLE. The binding of HuPlt CP to GCW is associated with loss of colloidal iron staining, a qualitative technique that demonstrates primarily epithelial cell surface anionic sialoglycoproteins. In experiments of in vitro binding of purified HuPlt CP to section of normal kidney treatment with heparin completely restores the normal pattern of colloidal iron staining suggesting ionic neutralization of GPA. In contrast, heparin is only partially effective in restoring colloidal iron staining in normal kidney sections treated with platelets directly stimulated with IC or PAF or in kidney sections of patients with SLE. These observations indicate that under these conditions the ionic interaction of HuPlt CP with GCW is only partially responsible for the loss of colloidal iron staining. The results of the present study suggest that biologically active polycationic mediators released from stimulated platelets localize in GCW and participate in the induction of glomerular injury.

The use of a hydroxylapatite-filter steroid receptor assay method in the study of the modulation of androgen receptor interaction

Receptors for androgen, estrogen, and glucocorticoid can be assayed by hydroxylapatite adsorption of the radioactive steroid-receptor complex and washing of the adducts on membrane filters mounted on a multiple filter holder. The method is economical, very rapid and sensitive. This new receptor assay method was used to study the modulation of androgen receptor of rat ventral prostate by metal ions, thiols, and ligand structure. The interaction of androgen with the naked receptor is inhibited by 10 microM ZnCl2, CdSO4, or CuSO4 but this inhibition is competed by androgen and is reversed by DTT. The androgen-receptor complex is less sensitive to divalent metal ions but Zn2+, at 3 mM, appears to alter the conformation of the receptor and promote the release of androgen. Certain phenanthrene derivatives exhibited striking structural specificities in their ability to compete with radioactive androgen for binding to the prostate receptor. The results suggest that the receptor has binding preference toward individual ring structure in the steroid.

The use of radioactive 7 alpha, 17 alpha-dimethyl-19-nortestosterone (mibolerone) in the assay of androgen receptors

Tritiated 7 alpha, 17 alpha-dimethyl-19-nortestosterone (DMNT; mibolerone), a synthetic androgen stable to metabolic conversion in the rat ventral prostate, is an excellent radioactive ligand for the quantitation and characterization of androgen receptors in prostate, liver, and cultured cells. DMNT is more receptor-selective than 17 alpha-methyl-17 beta-hydroxy-estra-4,9,11-trien-3-one (R1881); DMNT interacts with glucocorticoid and progestin receptors much less strongly than R1881. Unlike 5 alpha-dihydrotestosterone, DMNT does not bind tightly to testosterone-estradiol binding globulin of human serum. The hydroxylapatite-filter assay we employed can clearly distinguish between DMNT binding to androgen receptors of rat ventral prostate and interaction of DMNT with androgen binding protein of epididymides. The prostate cytosol (3H)DMNT-receptor complex sediments in two forms (4 and 8 S) in a low salt medium. In 0.4 M KCl, both the prostate cytosol and nuclear (3H)DMNT-receptor complexes migrated as 3-4 S components. The formation of both the cytosol and nuclear DMNT-receptor complexes is inhibited by antiandrogens and 17 beta-estradiol.

In vitro synthesis of polypeptides of moderately large size by poly(A)-containing messenger RNA from postmortem human brain and mouse brain

Studies were undertaken to optimize the conditions for isolation and in vitro translation of poly(A)-containing mRNA from human postmortem brain. The comparison of several methods for preparation of mRNA from frozen mouse brain indicated that although the yield of mRNA was increased using polysomes prepared in the presence of ribonucleoside vanadyl complexes and subsequently extracted with guanidinium thiocyanate, the translation products were indistinguishable from those synthesized by total cellular RNA directly extracted from tissue with guanidinium thiocyanate. The oligo d(T)-cellulose-purified poly(A)-containing mRNA preparations were translated in vitro in a rabbit reticulocyte lysate in the presence of L-[35S]methionine. Messenger RNA from frozen mouse brain stimulated protein synthesis from 9- to 20-fold over endogenous mRNA. Over 450 polypeptides were reproducibly synthesized and separated by two-dimensional polyacrylamide gel electrophoresis (PAGE); size classes up to 130,000 daltons were present. Direct extraction of RNA from frozen human cerebral cortex and cerebellum with guanidinium thiocyanate followed by oligo d(T)-cellulose chromatography yielded 1.8 micrograms/g and 2.0 micrograms/g, respectively, of poly(A)-containing mRNA; this represents a two- to fourfold increase over our earlier results. In the rabbit reticulocyte translation system human brain mRNA stimulated protein synthesis nearly threefold over endogenous mRNA. Compared with earlier studies, the number of newly synthesized polypeptides was increased by 30%. Over 300 species were separated by two-dimensional PAGE, and size classes up to 130,000 daltons were present, as compared to 70,000 in an earlier report. The polypeptides synthesized by human cerebral cortex and cerebellum were indistinguishable. However, several appeared to be uniquely human when compared with the products synthesized by mouse brain mRNA. The method described for the preparation of postmortem human brain mRNA eliminates the need to prepare polysomes, which are recovered in variable and low yield from the postmortem human brain. The procedure appears applicable to studies on the synthesis of moderately large human brain polypeptides and for investigations of brain protein polymorphism when relatively large numbers of products are required for analysis.

Enzymatic profile of Legionella pneumophilia

The enzyme activities of four strains of Legionella pneumophilia were investigated by using the API ZYM system (API System S.A., F-38390 Montalieu Vercieu, France) and synthetic substrates. Aminopeptidases were detected specifically against L-alanine, L-arginine, L-aspartic acid, L-cystine, L-glutaminic acid, glycine, L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-tryptophan, L-tyrosine, and L-valine. Furthermore, the bacteria possesses esterase activity splitting propionate, butyrate, caproate, caprylate, and caprate, but not laurate, myristate, palmitate, and stearate, esters. The enzymes studies were inhibited partially by aprotinin. No inhibition of phosphatase (pH range, 5.4 to 8.5) or of phosphoamidase was observed. Activities of arylsulfatase, chymotrypsin, trypsin, and glycosidases could not be detected.

The trypsin and chymotrypsin inhibitors in chick pears (Cicer arietinum L). The relationships among the six isoinhibitors

The six isoinhibitors of trypsin and chymotrypsin which were previously purified from a crude extract of chick peas were further studied with the intention of establishing the relationships among them. Exposure of each fraction to active, matrix-bound trypsin resulted in a decrease of the specific inhibitory activities towards trypsin of fractions P-1, P-3 and P-5 while those of P-4 and P-6 were increased. Each of these fractions was separated into several sub-fractions after chromatography on a DEAE-Sephadex A-25 column under conditions identical to those used previously for their purification. The elution positions, specific inhibitory activities towards trypsin and electrophoretic patterns in polyacrylamide gels of the various sub-fractions were determined...

[Inhibition of cathepsins from trout muscle and from bovine spleen by proteinase inhibitors of potato tubers (author's transl)]

The cathepsins D from trout muscle and from bovine spleen, as well as cathepsin A from bovine spleen are inhibited by a crude proteinase inhibitor from potato tubers. Cathepsins C and B1 are not inhibited. It was shown by isoelectric focussing that several inhibitors for cathepsin D are present in potatoes. Those with isoelectric points at pH 9.2, 9.1, 9.0, 8.9, 8.5 inhibit cathepsins D both from trout muscle and from bovine spleen. In addition some inhibitors with isoelectric points at pH 6.6, 6.5, and 6.2 were observed, which inhibit cathepsin D from trout muscle only.

The trypsin and chymotrypsin inhibitors in chick peas (Cicer arietinum L). Identification of the trypsin-reactive site, partial-amino-acid sequence and further physico-chemical properties of the major inhibitor

The two principal isoinhibitors P-5 and P-6 isolated earlier from the seeds of chick peas (Cicer arietinum L.) by a procedure involving biospecific affinity chromatography on active, matrix-bound trypsin are shown to be the virgin and trypsin-modified forms of the same inhibitor. The virgin inhibitor P-5 consists of a single peptide chain of 66 amino acid residues cross-linked by seven disulfide bridges. Upon interaction with the matrix-bound trypsin under the conditions used the virgin inhibitor P-5 is about 50% converted to P-6 by cleavage of a single Lys-Ser linkage at position 14-15 in the molecule. The resulting tetradecapeptide remains bound to the rest of the molecule by two or four disulfide bridges, but the two fragments representing residues 1-14 and 15-66 separate readily by molecular-sieve chromatography following reductive or oxidative cleavage of the disulfide linkages. The sequence 1-25 was established by Edman degradation.

The trypsin and chymotrypsin inhibitors in chick peas (Cicer arietinum L.). Purification and properties of the inhibitors

From a crude extract of chick peas (Cicer arietinum L.) inhibitors of trypsin and chymotrypsin were isolated by affinity chromatography on a column of trypsin-Sepharose 6B. The content of inhibitors was found to be 1.5 g/kg. They were further separated into six isoinhibitors by ion-exchange chromatography on DEAE-Sephadex A-25. Two of the isoinhibitors accounted for about 50% of the isolated inhibitors and were further purified to a homogeneous state. The isoinhibitors had a molecular weight of about 10000 as determined by molecular-sieve chromatography on Sephadex G-75. They were stable towards extremes of pH and temperatures up to 75 degrees C or towards digestion by pepsin. They were also stable in 6 M urea but not in 6 M guanidine-HCl. The intact inhibitors were destroyed when the peas were cooked at 100 degrees C or when they were toasted at 130 degrees C. The four major inhibitors had similar amino acid compositions and did not contain detectable amounts of free sulfhydryl groups, tryptophan or carbohydrate. Cysteine is the dominant amino acid residue in all of them and accounted for about 20% of their amino acid content. The isoelectric point of the isoinhibitors lies in the range of pH 4.9-8.6 and two of the major inhibitors had isoelectric points of pH 4.75 and pH 4.96. They inhibited chymotrypsin to the same extent but differed in their inhibitory activities towards trypsin, indicating that they are mixtures of native and trypsinmodified forms and that they probably have separate sites for the two enzymes. They did not inhibit other proteolytic enzymes belonging to two groups (i.e., serine or cysteine enzymes) or originating from different sources (i.e., animals, plants or bacteria).