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Three aspects of the pathophysiology of acute pancreatitis are discussed: 1. the initiating mechanisms, 2. the mechanisms of the fat necrosis, 3. the processes leading to shock phenomena. It is pointed out that the intraglandular activation of the precursors for both lipolytic and proteolytic enzymes seems to be essential for the initiating mechanisms of the disease. The role of the hormone dependent lipolytic enzyme of the fat tissue is discussed in relation to the occurrence of extrapancreatic fat necrosis. The role of the vaso-active compounds, such as plasma kinins and histamine for the occurrence of shock during acute hemorrhagic pancreatitis is pointed out.

In order to clarify the role of active trypsin, bile acids and pepsin in reflux oesophagitis, a comparable series of experiments was performed in rats before and after reflux-inducing operations. Three control procedures were used--laparotomy (n = 10), oesophageal transection and reanastamosis (n = 7) and a Roux-en-Y reconstruction (n = 9)--and seven experimental procedures in order to produce gastric, bile and pancreatic reflux (G + B + P) (n = 9), gastric and pancreatic reflux (B + B) (n = 8), bile and pancreatic reflux (B + P) (n = 10), pancreatic reflux alone (P) (n = 9), gastric reflux alone (G) (n = 8), bile reflux alone (B) (n = 9) and gastric with bile reflux (G + B) (n = 9). Macroscopic and histologically confirmed oesophagitis was produced in groups G + B + P, G + P, B + P and P. The trypsin levels were significantly elevated in these groups, compared to both the control and other experimental groups (P less than 0.01). Bile acid levels were insignificantly different between the groups. Because these experiments involved vagal transection, no oesophagitis was found in the gastric juice reflux group. This study has shown for the first time a correlation between the presence of active trypsin in the oesophagus and the occurrence of oesophagitis. It is possible that active components of duodenal juice may contribute to the development of reflux oesophagitis in man.

We review the mechanisms underlying the feedback regulation of pancreatic enzyme secretion in response to a meal. Pancreatic enzyme secretion in the rat and pig is known to be regulated by a negative feedback mechanism mediated by intestinal trypsin and chymotrypsin. Such a mechanism has recently been noted in humans. The presence of these enzymes in the small intestine suppresses pancreatic enzyme secretion, whereas their removal increases it. Two novel peptides have been proposed to account for the stimulation of pancreatic enzyme secretion in response to feeding trypsin inhibitor. One was assumed to be present in rat pancreatic juice and the other to be spontaneously secreted from the rat small intestine. In either case, trypsin and trypsin inhibitors do not directly interact with the luminal surface of the small intestine, but their actions are mediated by a trypsin-sensitive, cholecystokinin-releasing peptide. This is a novel explanation of the well-recognized stimulation of pancreatic enzyme secretion in response to dietary protein intake.

Since the first observation in 1979 that CF infants have elevated blood IRT, studies in various centres have enabled us to more fully understand the importance of this phenomenon. There is increasing evidence to show that mass newborn screening for CF using the IRT assay is practical and is capable of detecting essentially all CF newborns at a cost comparable to existing screening programs for other disorders such as Hypothyroidism. Although the elevated IRT levels seen in infancy in CF soon decrease, IRT levels in older CF patients appear to quite closely reflect the capability of that patient to secrete pancreatic enzymes and can be helpful in separating CF patients whose ability to secrete enzymes is preserved, from those with diminished exocrine pancreatic function. In all CF patients there appears to be an altered relationship between pancreatic exocrine secretion and circulating IRT levels as compared to control patients. This is probably one further manifestation of a secretory obstructive defect which although not uniformly severe, is common to all CF patients.

The pathogenesis of a spontaneously occurring exocrine pancreatic insufficiency (EPI) syndrome in CBA/J mice was studied at the ultrastructural level. Initial cytologic manifestations of this syndrome are seen as a progressive digestion of the zymogen granules, beginning at the periphery and proceeding toward the granule interior. Granule membrane breakdown, fusion of neighboring granules, and a release of zymogen contents into the cytoplasm are frequently observed in later stages; in some cases the entire granule contents appear digested before membrane breakdown is observed. In either case, pathologic changes are subsequently observed in mitochondria and rough endoplasmic reticulum. Remnants of lysed cells are then engulfed by invading macrophages, and infiltration by fat cells is observed. Secretory ducts and islets of Langerhans show no pathologic changes even after total autolysis of the exocrine pancreas. Morphologic evidence showing zymogen granule destabilization, coupled with biochemical evidence presented in an accompanying paper, indicate that intracellular autodigestion is the mechanism of exocrine cell death.

Esophagitis has been associated with the reflux of acidic gastroduodenal contents. These contents may contain not only HCl but also pepsin, bile, and pancreatic enzymes. This experiment was designed to compare the roles of these components in experimental acid esophagitis. The esophagus of the rabbit was cannulated and perfused continuously via a recirculating system with pH 2 acid test solution. Net flux of H+, K+, glucose, and hemoglobin plus the recovery of tritiated water were determined before and after the addition of pepsin, taurodeoxycholate, or trypsin. Afterward the esophageal segments were graded for gross and microscopic esophagitis. These studies show that pepsin caused significant gross and microscopic esophagitis. Moreover, pepsin also caused significant increases in H+, K+, glucose, and hemoglobin flux as well as decreased recovery of tritiated water. Taurodeoxycholate increased esophageal mucosal permeability to H+, K+, and glucose and decreased the recovery of tritiated water but did not cause significant pathologic change. Trypsin and acid alone did not result in significant esophagitis by either pathologic or ionic permeability criteria. These results show tha disruption of the esophageal mucosal barrier cannot be equated with pathologic injury and that different components of the gastroduodenal contents may have different sites or mechanisms of injury.

The receptor-mediated endocytosis of gold-labelled alpha 2-macroglobulin complexes with trypsin or methylamine (alpha 2M-T-Au or alpha 2M-MA-Au) was studied by electron microscopy in human skin fibroblasts. The gold label was found in coated structures and very small tubules as well as in tubulovesicular structures and in multivesicular bodies/lysosomes. Thick sections (200 nm), but especially serial thin sections, clearly showed the polymorphic character of the cellular structures involved in endocytosis. Numerous intercommunications were particularly obvious between the tubulovesicular structures, the larger vesicles and the multivesicular bodies (MVB). Continuities between MVBs and endoplasmic reticulum and interconnections between MVBs were also observed. The specificity of the staining reaction was confirmed by indirect labelling of intracellular alpha 2M by polyclonal and by monoclonal antibodies on ultracryosections. These findings are discussed in relation to observations made on epithelial cells with other ligands.

In view of the fact that trypsin enhances the infectivity of human rotavirus and decreases its hemagglutination, the trypsin-mediated structural modification of the viral polypeptides was analysed, using the KUN strain, a cultivable human rotavirus isolate, grown in the absence of trypsin. A major polypeptide sensitive to trypsin treatment was Vp4 with a molecular weight of 80,000, being cleaved into three polypeptides with molecular weights of 54,000 (P54), 30,000 (P30), and 24,000 (P24). Vp4 was also sensitive to chymotrypsin treatment, generating cleavage products different from those obtained with trypsin.

We measured the levels of trypsin-releasable spasmogenic substances (TRSS) in the plasma of spontaneously hypertensive rats (SHR) during the development of hypertension. TRSS levels (means +/- SEM, N = 4) were significantly higher at 12 weeks (7.13 +/- 1.05 micrograms bradykinin equivalents (BKE)/ml plasma) and 24 weeks (6.87 +/- 0.60 micrograms BKE/ml) compared to 8 weeks (3.3 +/- 0.55 micrograms BKE/ml) and to normotensive Wistar Kyoto (WKN) rats, whose levels were 3.74 +/- 0.74 micrograms BKE/ml at 24 weeks and did not change significantly during the period studied. The mean arterial pressure (MAP) of SHR was 150-170, 160-180 and 170-220 mmHg at 8, 12 and 24 weeks, respectively, whereas the WKN MAP was 110-120 mmHg at 24 weeks. The increase in total TRSS was due to substances which elicit the slow contraction of the isolated guinea pig ileum and which could be distinguished from BK, T-kinin and other BK homologues by gel filtration on Sephadex G-25, gradient elution chromatography on CM-cellulose and by the slow rate of contraction of the guinea pig ileum. All of these properties are the same as those we have previously demonstrated for TRSS of Goldblatt 1-kidney 1-clip renal hypertensive rats and which are due, at least in part, to a 14 amino acid peptide whose composition does not correspond to any known spasmogenic substance.

Existence of feedback inhibition of pancreatic secretion by luminal pancreatic trypsin in humans is controversial. We examined the effect of duodenal tryptic activity on pancreatic, biliary, and gastric functions. In six healthy volunteers, gastric acid secretion and emptying and the secretion of pancreatic enzymes, bicarbonate, and bile acids into the duodenum were measured for 7 hr with a double-marker perfusion technique. Each experiment consisted of six test periods. The effects of the addition of active and inactive aprotinin to duodenal saline perfusion were determined during fasting and after administration of a saline test meal. We found that (1) aprotinin eliminated tryptic activity in the preprandial state and reduced it by more than 95% during meal periods; (2) compared to inactivated aprotinin, no differences in the outputs of bicarbonate, amylase, lipase, chymotrypsin, and bile acids occurred during preprandial or postprandial aprotinin periods; and (3) gastric acid secretion, emptying, and duodenogastric reflux were similar during aprotinin and inactivated-aprotinin perfusions. We conclude that short-term, almost complete reduction of intraduodenal tryptic activity does not alter exocrine pancreatic secretion or gastric function in the unstimulated state or in response to a moderate stimulation by a saline test meal. Therefore the importance of negative feedback control of pancreatic secretion by acute alteration of intraduodenal tryptic activity must be questioned in healthy humans.

An indirect immunofluorescent procedure was used to determine whether zonae of unfertilized and fertilized eggs would bind antibodies specific for hamster reproductive tract antigens. Appropriate controls indicated that the fluorescent staining was probably due to antigen-antibody interactions. Antigens were not detected in zonae of ovarian eggs. However, components in zonae of unfertilized eggs collected from the oviduct at metestrus, mid-diestrus, and late diestrus bound antibodies specific for oviductal and uterine antigens. The antigens appeared to be concentrated in a peripheral band within the zona. An outer area of the zona around the eggs obtained from the uterus at proestrus also bound the antibodies, although the fluorescent staining was relatively faint. Antigens were observed in the peripheral area of zonae of fertilized eggs collected from oviducts on days 1 and 2 postcoitum. However, the antibody-binding component of the zona was noticeably reduced in embryos taken from the uterus on day 3 of pregnancy. The results are consistent with the idea that the zonae of both unfertilized and fertilized hamster eggs are composed of layers and that the outer region contains specific antigens which are dereived from the oviduct. Furthermore, loss or alteration of these components in the zona of an embryo (but not of an unfertilized egg of the same postovulation age) may reflect some chemical or structural change which is a prerequisite for zona shedding. Anti-uterus sera (unabsorbed and absorbed) did not interfere with zona removal by trypsin, indicating that the antigens detected in the present study are different from the receptor sites which bind anti-ovary antibodies and certain plant agglutinins (as reported by other workers).

Inhibition of intraduodenal trypsin stimulates pancreatic secretion in rats and swine. This finding is controversial in healthy humans. The present study was designed to find whether a 'negative-feedback' mechanism exists in man. A 7-lumen tube equipped with two balloons was passed into the duodenum in 18 healthy volunteers. During a constant intravenous infusion of secretin (0.1 CU/kg/h) the duodenum was perfused with 0.9% NaCl solution (20 ml/10 min). Polyethylene glycol (10 g/l) served as nonabsorbable marker. Aprotinin (0.5 X 10(6) KIU/10 min or 1 X 10(6) KIU/10 min) was perfused intraduodenally during periods of constant pancreatic enzyme secretion for 30 min. During perfusion of the trypsin inhibitor aprotinin an almost complete inhibition of trypsin could be observed. However, at the same time or following the perfusion of aprotinin a significant augmentation of amylase, lipase or volume secretion did not occur. Thus, in the present study a negative-feedback control of pancreatic exocrine secretion by the intraduodenal trypsin concentration in man could not be demonstrated.

The activating effect of peptides sequentially related to the Ile 16-Val17-Gly18 N-terminus of bovine beta-trypsin (namely Ile-Val-Gly, Ile-Val, Ile-Leu, Ile-Ala, Val-Val, Leu-Val, and Val-Leu) on the thermodynamic parameters for the binding of the porcine pancreatic secretory trypsin inhibitor (Kazal inhibitor) and benzamidine to bovine trypsinogen was investigated at pH 5.5 (Bis tris-HCl buffer, I = 0.1 M) and T = 21 +/- 0.5 degrees C. Thermodynamic parameters for Kazal inhibitor and benzamidine association to the binary peptide/zymogen adducts are more favorable than those observed for ligand binding to the proenzyme alone, although never as much as those reported for the formation of bovine beta-trypsin/Kazal inhibitor and bovine beta-trypsin/benzamidine adducts. Analogously, the affinity of activating peptides for the binary proenzyme/Kazal inhibitor and binary proenzyme/benzamidine complexes is higher than that observed for peptide binding to free bovine trypsinogen. Differences in affinity for ligand binding to free bovine trypsinogen, to its binary adducts and to bovine beta-trypsin suggest the presence of different activation levels of the proenzyme, none of which structurally coincide with that achieved in bovine beta-trypsin. The existence of different discrete states suggests that the zymogen-to-active enzyme transition should not be considered as a two-state process but as a multistep event.

The mechanism by which the metabolic effects of insulin are transmitted is yet to be resolved. Second messengers mediating the action of insulin have been proposed and recently an insulin-dependent, peptide-like, heat- and acid-stable substance (Mr approx. 1000-3000) released from plasma membranes has been described which regulates the activity of key enzymes such as pyruvate dehydrogenase by altering its state of phosphorylation. It has been suggested that this material is the elusive second messenger of insulin and its discovery, generation, properties, isolation and mode of action are reviewed.

Pigs were surgically prepared with external pancreatic fistulae and duodenal cannulae in order to elucidate whether the proposed intestinal feedback control of pancreatic secretion in the pig--as in rat and man--is exerted by trypsin. Furthermore, the effect of intraluminal amylase on pancreatic secretion was studied. Reintroduction of pancreatic juice into the duodenum or infusion of trypsin into the duodenum depressed the volume of the pancreatic flow and the protein output markedly. Introduction of amylase into the duodenum did not significantly affect the pancreatic secretion. Thus, it seemed as it trypsin but not amylase was involved in the suppression exerted by pancreatic juice on exocrine pancreatic secretion in the pig.

The plasma enzyme responsible for primary proteolytic cleavage of growth hormone-releasing hormone (GRH) at the 2-3 amino acid bond was characterized. Native GRH[GRH(1-44)-NH2 and GRH(1-40)-OH], and COOH-terminally shortened fragments [GRH(1-32)-NH2 and GRH(1-29)-NH2] were rapidly cleaved, while GRH(2-32)-NH2 was not degraded at this site. Moreover, degradation to GRH(3-44)-NH2 was unaffected by an aminopeptidase inhibitor, indicating that this metabolite was generated from a single step cleavage by a dipeptidylpeptidase (DPP) rather than sequential aminopeptidase cleavages. Conversion to GRH(3-44)-NH2 was blocked by diprotin A, a DPP type IV (DPP IV) competitive inhibitor. D-Amino acid substitution at either position 1 or 2 also prevented hydrolysis, characteristic of DPP IV. Analysis of endogenous plasma GRH immunoreactivity from a human GRH transgenic pig revealed that the major peak coeluted with GRH(3-44)-NH2. Native GRH exhibited trypsin-like degradation at the 11-12 position but cleavage at the 12-13 site occurred only with GRH(1-32)-NH2 and GRH(1-29)-NH2. Formation of these metabolites was independent of prior DPP IV hydrolysis but was greatly reduced by trypsin inhibitors. Evaluation of plasma stability of potential GRH super analogues, designed to resist degradation by these enzymes, confirmed that GRH degradation in plasma occurs primarily by DPP IV, and to a lesser extent by trypsin-like enzyme(s).

We have investigated a negative feedback mechanism in the intestinal phase of pancreatic exocrine secretion in dogs with gastric cannulas and Thomas duodenal cannulas in whom pancreatic juice was collected by cannulation of the main pancreatic duct. Intraduodenal infusion of oleic acid emulsion in a dose of 18 mmol/h resulted in a significant increase in pancreatic secretion of water, bicarbonate, and protein, which was accompanied by increased plasma concentrations of both secretin and cholecystokinin. Infusion of pancreatic juice or bovine trypsin into the duodenum significantly inhibited the oleic acid-stimulated pancreatic secretion. This inhibition coincided with a significant decrease in plasma secretin level, whereas plasma cholecystokinin concentration was not affected by either pancreatic juice or trypsin. Neither pancreatic secretion nor plasma secretin concentration was affected by intraduodenal administration of NaHCO3 solution. The trypsin-induced suppression of pancreatic secretion was prevented by intravenous administration of secretin in a dose that achieved a plasma secretin level comparable to that during the oleic acid administration. This study indicates that a negative feedback mechanism is operative in the intestinal phase of pancreatic exocrine secretion in dogs, and endogenous secretin plays a significant role in the mechanism.

A sensitive avian growth hormone (GH) radioreceptor assay (RRA) was developed using recombinant chicken growth hormone (rcGH) and a membrane receptor preparation of chicken or turkey livers. The specific binding of 125I-labeled rcGH to a 47,800 X g pellet was 33-36% in a 16-20 h incubation period at 4 degrees C. Binding was time, temperature and pH dependent. Scatchard analysis indicated a single class of high affinity GH binding sites in chicken and turkey livers, with binding affinities of 1.03 X 10(10) liter/M and 1.11 X 10(10) liter/M, respectively, and corresponding binding capacities of 10.7 fmol and 21 fmol per mg protein. The sensitivity of the assay was 0.41 ng of rcGH. Intra- and inter-assay coefficients of variation were 5.3% and 9.7%, respectively. Bovine GH, ovine GH, and porcine GH competed effectively for the GH binding sites in chicken and turkey livers. Turkey prolactin (PRL) and porcine PRL showed little cross-reaction (less than 0.07%), while cross-reaction of ovine and bovine PRL was greater (less than 10%). Standard rcGH (0.5-30 ng) was added to sera from hypophysectomized chickens and turkeys (hypox sera) and to tissue culture medium and was measured quantitatively. Untreated medium (10-100 microliters) and hypox sera (5-40 microliters) did not inhibit rcGH binding. These studies report the existence of specific binding sites for avian GH in chicken and turkey liver and validate a sensitive RRA for measurement of bioactive GH in sera and tissue culture medium.

The infectivity of influenza A viruses like fowl plague virus (FPV) with a cleaved hemagglutinin (HA) is highly sensitive to treatment at pH 5, while strains like PR 8 or virus N with a noncleaved HA survive under this condition. After double infection of chick embryo cells with FPV and PR 8 or virus N, the yield of virus with the HA gene of FPV is greatly reduced. However, it can now survive treatment at pH 5, and the surviving FPV particles form plaques only in the presence of trypsin, indicating that they were coated by the HA of PR 8 or virus N, depending on the coinfecting virus. The results are discussed with respect to the build-up and maintenance of a large reservoir of nonpathogenic influenza A viruses with noncleavable HA in water fowl.

Since the trypsin activity of the inner ear fluid appears to be essential in the evolution of otosclerosis towards a cochlear deafness it was obvious that the protease inhibitor system which is an excellent genetic marker ought to be studied during the onset and the evolution of otosclerosis. No differences with the statistical data from the normal population was found the origin of the trypsin that destroys the inner ear is to be found locally the histiocytes of the otosclerosis focus.

Pepsin and trypsin cause erosive, hemorrhagic lesions in our rabbit model of experimental esophagitis. Since the gastroduodenal contents of patients with reflux esophagitis may also contain bile salts, we used our model to determine the effect that a bile salt, taurodeoxycholate (TDC), would have on the esophageal mucosa when combined with either pepsin in an acid perfusate (pH 2) or trypsin in an alkaline perfusate (pH 7.5). Indexes of esophageal injury included gross appearance of the mucosa, microscopic examination, and mucosal barrier integrity as determined by permeability to hydrogen ion. We found that when 5 mM TDC was combined with pepsin (0.3 mg/ml), the gross and microscopic changes of esophagitis, as well as net hydrogen ion flux, were diminished when compared with those observed with pepsin exposure alone. When increasing concentrations of TDC (2 to 10 mM) were added to pepsin, the morphologic degree of injury as well as hydrogen ion flux decreased in a dose-dependent manner. In contrast, when 5 mM TDC was combined with trypsin (1000 U/ml) in the alkaline perfusate, the gross and microscopic changes of esophagitis and the net of hydrogen ion flux were increased when compared with either bile salt or trypsin alone. These effects were also dose dependent. These data demonstrate that bile salts present in the gastroduodenal contents of patients with reflux esophagitis have the capacity to modulate the effects of pepsin and trypsin on the esophageal mucosa.

Malignant cells have the ability to invade and metastasize in great part because they secrete proteolytic enzymes. In order to investigate if the abnormal proteinase/antiproteinase balance of cancer bearing patients changes when the malignant tumor is destroyed, we studied 50 patients with invasive carcinoma of the cervix and 33 healthy women as a control group. Patients with cancer were treated with radiation according to the protocols of our hospital. The following serum determinations were performed: plasminogen activators (PA), cathepsin B (CB), antiproteinase alpha-1-antitrypsin (A1AT), trypsin inhibitory capacity (TIC) and antiproteolitic activity ratio (AAR), all of them before and after treatment. Serum proteolytic activity was elevated manyfold in all patients with invasive tumor as well A1AT. The antiproteolytic activity however, was significantly reduced to about 50% of its normal value in the same group of patients. In patients with good response to radiotherapy (tumor necrosis) a great reduction of proteinase activity as well as a recovery to normal of the AAR was observed. Contrary, in those with a poor response after radiation, proteolytic activity remained elevated and AAR diminished. It is concluded that serum PA, CB, A1AT and AAR values can be precise indicators of the presence of malignancy. These tests might be also of help for improving follow-up studies and for better prognostic estimates.

The effect of atropine on exocrine pancreatic secretion was investigated in conscious rats. Intravenous atropine infusion decreased nonstimulated protein secretion during recirculation of pancreatic juice into the duodenum D50 = 15-20 micrograms/kg/h. The maximum inhibition from protein secretion (-89%) was obtained with 600 micrograms/kg/h. With larger doses, the inhibition was less. The response to secretin and cholecystokinin-pancreozymin was not significantly modified by atropine. When pancreatic juice was diverted during the course of an intravenous atropine infusion, the first 1-hour peak of protein output was significantly decreased, but the following 2-hour period was increased, the sum of these 2 periods being similar in both conditions. The response to soybean trypsin inhibitor during recirculation was decreased as well as the first peak after diversion. During atropine infusion fluid secretion decreased more powerfully after 1 h diversion and after soybean trypsin inhibitor than during recirculation of pancreatic juice. It is suggested that during recirculation of pancreatic juice nonstimulated protein secretion is mostly (89%), and water secretion is partially controlled by cholinergic mechanisms. After soybean trypsin inhibitor stimulus and during the early phase following juice diversion protein secretion seems to be partly under the control of cholinergic mechanisms. However, during the latter phase following diversion, it is not so. Parasympathetic stimulation appears also to play a significant, although less important, role in fluid secretion.

Esophagitis occurs in patients with excessive acid and/or alkaline gastroesophageal reflux. This observation prompted us to develop a continuously perfused in vivo rabbit esophageal model to examine the potential for different endogenous injurious agents to cause H+ back diffusion and morphologic evidence of esophagitis. We found that HCl at physiologic pH values did not break the mucosal barrier to H+ back diffusion or cause esophagitis. Bile salts at physiologic concentrations in both an acid or alkaline perfusate broke the mucosal barrier and caused H+ back diffusion, but failed to cause a morphologic injury consistent with clinical reflux esophagitis. Instead, proteolytic enzymes, such as pepsin in an acid environment and trypsin in an alkaline environment, caused a severe hemorrhagic erosive esophagitis consistent with that seen clinically. We feel new therapeutic strategies for the treatment of reflux esophagitis should be directed at proteolytic enzymes rather than only HCl or bile salts. Finally, we showed sucralfate to be a mucosal protectant against the acid-pepsin injury.

The plasma proteinase inhibitor corresponding to alpha-1-proteinase inhibitor (alpha 1Pl) in humans was isolated from sheep plasma. Ovine alpha 1Pl is of higher molecular weight (62,000 daltons) than is human alpha 1Pl, is resistant to chemical oxidation by N-chlorosuccinimide, and has poor elastase-inactivating power compared with the corresponding inhibitor in humans. However, ovine alpha 1Pl is a potent trypsin inhibitor. Despite the differences indicated above, a partial homology (22 to 35%) exists between human and sheep alpha 1Pl, at least as analyzed through the first 20 residues of the sheep inhibitor. The weak elastase-inhibitory capacity of sheep alpha 1Pl is paralleled by the low content of elastase in the sheep neutrophil granule. These important differences between sheep and human neutrophils and plasma proteinase inhibitors should be borne in mind in designing experiments related to proteolytically mediated lung injury in the former species.

Murinoglobulin, a newly identified mouse plasma protein resembling alpha-macroglobulins [Saito, A. & Sinohara, H. (1985) J. Biol. Chem. 260, 775-781], was also found in guinea pig plasma, and purified to homogeneity. Guinea pig murinoglobulin consisted of a single 180-kDa polypeptide chain containing about 18% carbohydrate. It inhibited the proteolytic activities of trypsin and thermolysin towards Remazol brilliant blue hide powder, but stimulated the amidolytic activities of trypsin and Staphylococcus aureus V8 protease towards small synthetic substrates. Heat treatment of murinoglobulin completely abolished the former activities, but partially retained the latter activities. The ability of guinea pig murinoglobulin to inhibit the proteolysis was much weaker than that of the mouse homologue. On interaction with trypsin, murinoglobulin underwent cleavage of one susceptible bond with concomitant unmasking of one thiol group. Methylamine treatment also released one thiol group per molecule.

Digestibility trials were performed to study the suitability of mixtures made up of treated soybean and whey powder for replacing skim milk powder. Three different milk replacers were used, the replacers T-18/II and T-18/III containing Plyllac preparations manufactured by different technologies. When using the T-18 preparation with 18% fat content it was found that the protein source may contain 25% Plyllac preparation and 11% sweet whey powder. In two cases, at the age of 5 and 7 weeks, the digestibility of the crude protein in the T-18/II preparation was found to deteriorate significantly. For this reason, the authors suggest this milk replacer to be used from the 5th week of life. Trials were performed with 3 milk replacers (lactine preparations) containing Plyllac preparations of different manufacturing technology (35%), treated soybean (10%) and sweet whey powder (10%). It was found that the use of Plyllac preparations, i.e. of treated soybean in larger amounts causes the nutrient digestibility, mainly that of crude protein, to be significantly lower at the age of 3 and 5 weeks than that at the age of 7 to 9 weeks. No significant differences were found in the digestibility of the various Plyllac preparations manufactured by different technologies. The milk replacer lactine is recommended for use from the 5th week of life on.

We have demonstrated that arginine vasopressin (AVP) is degraded to desglycinamide AVP by a trypsinlike enzyme found in guinea pig amniotic fluid. Incubation of [3H]AVP with guinea pig amniotic fluid in vivo or in vitro produced a metabolite that comigrated on high-pressure liquid chromatography with desglycinamide AVP in three different buffer systems. Also, AVP antisera that cross-reacted with standard desglycinamide AVP could detect this amniotic fluid metabolite. Because the enzyme responsible for the cleavage of glycinamide from AVP was likely to be trypsin, experiments with aprotinin, a trypsin inhibitor, were conducted. Results demonstrated that the production of the amniotic fluid AVP metabolite could be completely blocked in the presence of the trypsin inhibitor. In addition, examination of amniotic fluid collected from fetuses in the second half of gestation (term = 68 days) showed that AVP could not be metabolized to desglycinamide AVP until after 52 days of gestation. In conclusion, AVP appears to be metabolized by a trypsinlike enzyme in amniotic fluid, and because trypsin is a general proteolytic enzyme, the amniotic compartment may also serve as a clearance site for other proteins.