Symptom contamination of life event scales

One hundred and seventy postpartum women completed the Social Readjustment Rating Scale (SRRS) and the Beck Depression Inventory (BDI). The point-biserial correlation between each item on the SRRS and the BDI was calculated. The four items identified by Lehman (1978) as being symptoms rather than life events per se were more highly correlated with the BDI than the remaining items. However, the correlation between the life event scale and the BDI was not significantly lowered after these items were removed. It is concluded that while life event scales should not include such symptom-like items, the contention made by some critics of the life event literature that all research using the Holmes and Rahe instrument is undermined soley because of the inclusion of these items, may be inappropriate.

Human plasma kallikrein releases neutrophil elastase during blood coagulation

Elastase is released from human neutrophils during the early events of blood coagulation. Human plasma kallikrein has been shown to stimulate neutrophil chemotaxis, aggregation, and oxygen consumption. Therefore, the ability of kallikrein to release neutrophil elastase was investigated. Neutrophils were isolated by dextran sedimentation, and elastase release was measured by both an enzyme-linked immunosorbent assay, and an enzymatic assay using t-butoxy-carbonyl-Ala-Ala-Pro-Val-amino methyl coumarin as the substrate. Kallikrein, 0.1-1.0 U/ml, (0.045-0.45 microM), was incubated with neutrophils that were preincubated with cytochalasin B (5 micrograms/ml). The release of elastase was found to be proportional to the kallikrein concentration. Kallikrein released a maximum of 34% of the total elastase content, as measured by solubilizing the neutrophils in the nonionic detergent Triton X-100. A series of experiments was carried out to determine if kallikrein was a major enzyme involved in neutrophil elastase release during blood coagulation. When 10 million neutrophils were incubated in 1 ml of normal plasma in the presence of 30 mM CaCl2 for 90 min, 2.75 micrograms of elastase was released. In contrast, neutrophils incubated in prekallikrein-deficient or Factor XII-deficient plasma released less than half of the elastase, as compared with normal plasma. The addition of purified prekallikrein to prekallikrein-deficient plasma restored neutrophil elastase release to normal levels. Moreover, release of elastase was enhanced in plasma deficient in C1-inhibitor, the major plasma inhibitor of kallikrein. This release was not dependent upon further steps in the coagulation pathway, or on C5a, since levels of elastase, released in Factor XI- or C5-deficient plasma, were similar to that in normal plasma, and an antibody to C5 failed to inhibit elastase release. These data suggest that kallikrein may be a major enzyme responsible for the release of elastase during blood coagulation.

Weighted versus unweighted life event scores: is there a difference?

Life events researchers differ in their opinions as to whether weighted life event indices are more strongly associated with measures of pathology than a simple count of the number of experienced events. In the present review, it was found that across 18 studies the average correlation between weighted and unweighted totals was .94. In 16 of 19 studies, weighted scores did not improve the stress-illness correlation.

Using personal scalings on life event inventories to predict dysphoria

The predictive ability of subjective weights of life events was examined. The focus of this study was the event 'doing very poorly on an important exam.' Two days before taking their midterm in an introductory psychology class, 164 students rated 120 life events as to the degree of negative impact on their life they believed the event did have (if it previously occurred) or would have (if it had not occurred). The subjects also filled out the Depressive Adjective Checklist (DACL) and the Beck Depression Inventory (BDI). One week later, on the day the grades were returned to the students, the second testing session was held. One hundred thirty-two subjects returned to again complete the two measures of depression. Thirty-three of the students were identified as having experienced the event. The results of a hierarchical multiple regression showed that the subjective rating of negative impact was a significant predictor of post-exam DACL scores but not post-exam BDI scores. Previous experience with the event was not associated with either post-exam depression measure. It is suggested that the perception of life events is an important variable in life event research and that subjective weights can be utilized as markers of individuals who are vulnerable to the effects of stress.

The dexamethasone suppression test and ECT outcome: a six-month follow-up

In an earlier report, the dexamethasone suppression test (DST) predicted globally rated outcome at discharge in 42 patients treated with ECT. To determine the predictive value of the DST following discharge we reevaluated these patients 6 months after admission. Suppressors and nonsuppressors did not differ in any of the follow-up measures; DST results added very little to the variance accounted for by diagnosis, age, and episode duration. Surprisingly, patients whose DST had converted at discharge from abnormal to normal were less likely to have sustained remission during follow-up than were patients whose DST had remained abnormal.

Comparison of the incidence of oncogenic transformation produced by X rays, misonidazole, and chemotherapy agents

An established line of mouse fibroblasts (10T1/2 cells) cultured in vitro was used to compare the incidence of oncogenic transformation produced by x rays, the hypoxic cell radiosensitizer misonidazole, and a range of commonly used chemotherapy agents. A 3-day exposure to misonidazole at a concentration obtainable during treatment produced an incidence of transformation similar to that of about 50 rad. When chemotherapy agents were tested at concentrations comparable to those used clinically and matched to produce similar cell killing, the incidence of transformation varied widely: some agents, such as vincristine, did not produce transformation at a level detectable above background, while others, such as cis-platinum, appear to be potent carcinogens and produce transformation at a rate orders of magnitude higher than that achieved with x rays.

Failure of one method of simultaneous chest compression, ventilation, and abdominal binding during CPR

Some modified methods of CPR improve carotid blood flow, but there are no studies to show that these modified techniques improve survival, Accordingly, an experimental CPR technique using simultaneous chest compression, ventilation (SCV-CPR), and abdominal binding was compared to standard CPR in beagle dogs. The modified technique utilized a broad-based bellows device that was mechanically compressed, producing chest compression, delivering a volume of air to the endotracheal tube, and pressurizing an abdominal binder. The duration of ventricular fibrillation and CPR was 5 min. Five of the 6 dogs could be resuscitated with standard CPR. None of 6 dogs could be resuscitated using this modified method of SCV-CPR and abdominal binding. The aortic diastolic pressure and the diastolic gradient between the aorta and right atrium was significantly different between the 2 groups. Because these pressures relate to the coronary perfusion pressure, they may explain the discrepancy in the survival rate. This study suggests increasing carotid blood flow during CPR will not necessarily improve survival.

Selective inhibition of human leukocyte elastase and bovine alpha-chymotrypsin by novel heterocycles

A number of N-arylbenzisothiazolinone 1,1-dioxides have been synthesized and examined for inhibitory activity against human leukocyte and porcine pancreatic elastase (EC 3.4.21.11), bovine alpha-chymotrypsin (EC 2.4.21.1), human leukocyte cathepsin G (EC 3.4.21.20), and bovine trypsin (EC 3.4.21.4). They are potent, selective, competitive inhibitors of human leukocyte elastase and chymotrypsin. The inhibitory capacity of these compounds is directly related to the electron-withdrawing capability of the aryl substituents. When sufficiently activated, the amide bond in the heterocyclic ring can be cleaved by the enzyme, resulting in inhibition which is highly specific. The most potent inhibitor of hummotrypsin. The inhibitory capacity of these compounds is directly related to the electron-withdrawing capability of the aryl substituents. When sufficiently activated, the amide bond in the heterocyclic ring can be cleaved by the enzyme, resulting in inhibition which is highly specific. The most potent inhibitor of human leukocyte elastase, the 2,4-dinitrophenyl derivative, has a Ki of 2.16 microM with elastase and 0.77 microM with chymotrypsin. This study demonstrates that it is possible to design specificity into non-peptide, low molecular weight serine protease inhibitors, which may have considerable pharmacologic potential.

Purification of a membrane-bound metalloendopeptidase from porcine kidney that degrades peptide hormones

A porcine kidney microsomal metalloendopeptidase has been enriched 3900-fold. Gel filtration on a calibrated Toyo-Soda G-3000 SW column indicated an appropriate molecular weight for the endopeptidase of 88,000 +/- 2000. The purified enzyme is inhibited by a number of synthetic inhibitors of thermolysin. The endopeptidase hydrolyzes the succinyl (Suc)-containing fluorogenic peptide substrate Suc-Ala-Ala-Phe-(7-amino-4-methylcoumarin) at the Ala-Phe position with a Km of 2.9 X 10(-4) M. The endopeptidase also hydrolyzes a variety of peptides including corticotropin, substance P, angiotensin I and II, neurotensin, somatostatin, bradykinin, and the renin tetradecapeptide substrate. The endopeptidase hydrolyzes both [Leu]- and [Met]enkephalin at the Gly-Phe bond.

Physiological effects of controlled concussive brain trauma

Utilizing a fluid percussion device, we measured the physiological effects of brain trauma in cats exposed to controlled levels of injury. Concussive brain injury at 3-4 atm of intensity led to profound elevations of the mean systemic arterial blood pressure from 128 +/- 26 to 229 +/- 33 mmHg, left ventricular end-diastolic pressure from 4 +/- 2 to 24 +/- 15 mmHg, and pulmonary wedge pressures (PWP) from 5 +/- 3 to 27 +/- 17 mmHg and a relatively moderate increase in intracranial pressure (ICP) from 6 +/- 3 to 38 +/- 31 mmHg (all P < 0.001). Pulmonary edema was evidenced by a significant increase in lung tissue wet-to-dry weight ratios to 3.74 +/- 0.81 as compared with a control group of 2.29 +/- 0.23 (P < 0.001). There was poor correlation between wet-to-dry weight ratios and PWP. Approximately 60% of all spontaneously breathing animals become permanently apneic within 6 min after injury, while the remaining 40% developed transient apnea. Arterial O2 or CO2 pressure alterations, in contrast to pretreatment with phentolamine did not affect the hemodynamic or edemogenic response to trauma. Phentolamine did not block the apneic response or increase in ICP. Comparative studies using intravenous levarterenol without trauma produced responses similar to trauma. Concussive brain injury of 3-4 atm results in pulmonary edema, apnea, sympathetically mediated peripheral vasoconstriction and left ventricular failure effect.

Inhibition of elastase and other serine proteases by heterocyclic acylating agents

The N-acylsaccharins and N-acylbenzoisothiazolinones form a new class of acylating inhibitors of the serine proteases with a broad spectrum of activity. However, they are unique in that they are able to differentiate between various serine proteases because of the differential stability of the presumptive acyl-enzyme formed. Furoyl saccharin was the best studied among this class of inhibitors. We report evidence that the amide bond in the heterocyclic ring of this compound is cleaved by porcine pancreatic and human leukocyte elastases and chymotrypsin, forming acyl-enzymes. Radioisotope studies indicate that the saccharin portion of furoyl saccharin is attached to these enzymes in approximately a 1:1 molar ratio with enzyme, blocking the active site serine. The acylelastases thus prepared are unusually stable to hydrolysis, with kdeacyl values at neutral pH of 2.3 x 10(-6) s-1 for porcine pancreatic elastase and 1.4 x 10(-6) s-1 for human leukocyte elastase. Trypsin appears to be inhibited by a different mechanism. These data suggest a new approach to the design of specific synthetic protease inhibitors.

A zinc metalloendopeptidase associated with dog pancreatic membranes

Assay of solubilized dog pancreas microsomes revealed the presence of an endopeptidase which hydrolyzed the fluorogenic peptide substrate Suc-Ala-Ala-Phe-7-amino-4-methylcoumarin (AMC) between the alanine and phenylalanine positions. This activity was inhibited by phosphoramidon, 1,10-phenanthroline, and a number of synthetic inhibitors of thermolysin indicating that the enzyme is a zinc metallopeptidase. Endopeptidase activity was not inhibited by the serine protease inhibitors elastatinal, antipain, leupeptin, N-carbobenzyloxy-L-phenylethyl chloromethyl ketone, L-tosylamido-2-lysyethyl chloromethyl ketone, L-tosylamido-2-phenylethyl chloromethyl ketone, phenyl-methanesulfonyl fluoride, or low levels of chymostatin. The endopeptidase had a pH optimum between 7.0 and 7.5. The enzyme also hydrolyzed Suc-Ala-Ala-Ala-AMC and Suc-Ala-Gly-Ala-AMC in an analogous way to yield Ala-AMC. Thermolysis hydrolyzed Suc-Ala-Ala-Phe-AMC in an analogous way to the endopeptidase. However, thermolysin did not hydrolyze Suc-Ala-Ala-Ala-AMC or Suc-Ala-Gly-Ala-AMC, demonstrating that its substrate specificity differs from the endopeptidase.

A new fluorogenic substrate for plasmin

A new fluorogenic peptide substrate for plasmin, 7-(N-succinoylalanylphenylalanyl-lysylamido)-4-methylcoumarin trifluoroacetate salt, was prepared that can be used in a simple and direct assay. The results obtained by the assay method are linear over a wide range of enzyme concentrations and sensitive enough to detect as little as 10(-5) CTA units of plasmin. By making use of the inhibitor Trasylol and the differences in kinetic constants, plasmin can be specifically assayed even in the presence of the plasminogen activator thrombin, as well as in culture fluids from HeLa cells.

Characterization of an endopeptidase involved in pre-protein processing

Proteolytic removal of the pre-segment from growing nascent chains of pre-human placental lactogen (hPL) occurred during in vitro translation of placental mRNA if crude membranes derived from ascites lysates, dog pancreas, or rat liver rough endoplasmic reticulum were added to the translation mixtures. The cotranslational proteolytic event was inhibited by the peptide protease inhibitor, chymostatin, but not by leupeptin, antipain, or elastatinal. The proteases involved in cleavage were solubilized with detergent and converted completed pre-hPL to hPL (post-translational processing). Direct assay of the solubilized membranes, with synthetic fluorogenic aminocoumarin peptide substrates, revealed no significant tryptic or elastase-like activity, but activity against a chymotrypsin substrate [(succinyl-Ala-Ala-Phe)-7-amino-4-methyl-coumarin] was found. This activity was dependent upon both an endopeptidase and an aminopeptidase. Although bestatin inhibited the aminopeptidase activity, it had no effect on the endopeptidase or on post-translational cleavage. Although this endopeptidase cleaved on the COOH side of an alanine residue, it was not inhibited by elastatinal. However, it was inhibited by high levels of chymostatin and by some serine protease inhibitors.

Direct fluorescent assay of urokinase and plasminogen activators of normal and malignant cells: kinetics and inhibitor profiles

A direct rate assay for plasminogen activator has been developed using a synthetic fluorogenic peptide substrate, 7-(N-Cbz-glycylglycylargininamido)-4-methylcoumarin trifluoroacetate. The assay correlates well with the standard 125I-labeled fibrin plate assay using highly purified urokinase, culture fluids from WI-38, Chinese hamster vary or HeLa cells, or Rous sarcoma virus-transformed chick fibroblasts as the source of plasminogen activator. The assay is sensitive, rapid, and linear throughout a wide range of enzyme concentrations. With this substrate it is possible to determine inhibitor profiles for the various plasminogen activators, independently of the interfering potential of plasmin. All of the enzymes tested are inhibited by leupeptin and antipain but not by the related aldehydes, elastatinal and chymostatin. The macromolecular inhibitors soybean trypsin inhibitor and trasylol have little or no effect on the plasminogen activators tested. This substrate should be useful for the study of the effect of various agents on functional changes in cells secreting this enzyme and also should allow kinetic measurements of potential inhibitors.

Cytochalasin B-dependent release of azurophil granule enzymes from human polymorphonuclear leukocytes

The dose-response effects of phorbol myristate acetate and cytochalasin B on secretion of azurophil and specific granule enzymes from viable human polymorphonuclear leukocytes have been examined. Secretion of the azurophil granule enzymes elastase and beta-glucuronidase from cells exposed to 50 ng/ml of phorbol myristate acetate is dependent on prior exposure of the cells to greater than 0.5 mg/ml of cytochalasin B. In contrast, the secretion of the specific granule enzyme lysozyme is not dependent on pretreatment with cytochalasin B. The concentration of phorbol myristate acetate needed to elicit maximal secretion of specific versus azurophil granule enzymes differs, being 5.0 ng/ml and 50 ng/ml, respectively. The results suggest that cytochalasin B-sensitive cellular components, possibly microfilaments, may selectively modulate some step in the exocytosis of azurophil granule enzymes from human polymorphonuclear leukocytes exposed to phorbol myristate acetate.

Proteinase inhibitors. I. Inhibitors of elastase

A series of peptides and depsipeptides containing 2-methylcarbazic acid (H-Mec-OH), the 2-aza analogue of alanine, was prepared and tested as inhibitors of pancreatic and human granulocyte elastases. A requirement for a minimum chain length as well as specific amino acid sequence was observed which correlates well with both substrate and inhibitor studies by others in this field. The most active inhibitors have the structure Ac-Ala-Ala-Pro-Mec-Lac-R. When Lac-R is an ester, only the pancreatic enzyme is inhibited. When Lac-R is an amide or hydrazide, then both enzymes are inhibited. The inhibitory activity is reversible; the inhibitors are not hydrolyzed by the enzyme and the inhibition is noncompetitive with synthetic substrates of similar structure, suggesting that binding at the sites adjacent to the carboyl group of the amino acid analogue, 2-methylcarbazic acid, is important for this inhibition. The data further demonstrate the differences between pancreatic and granulocyte elastases.

Inhibitors of folate biosynthesis. 1. Inhibition of dihydroneopterin aldolase by pteridine derivatives

2-Amino-6-carboxamido-7,8-dihydropteridin-4-one and 2-amino-6-hydroxymethyl-7,7-dimethyl-7,8-dihydropteridin-4-one have been shown to be good inhibitors of Escherichia coli dihydroneopterin aldolase, an early enzyme of de novo folate biosynthesis.

A controlled intrauterine contraceptive device trial

Three intrauterine contraceptive devices (IUCD) the Lippes Loop, the Dalkon Shield and the Inhiband, were prospectively compared after their random allocation to patients. Over a 12-month period after insertion, the Dalkon Shield was shown to be significantly superior to the Inhiband. Significant differences were not demonstrated between Shield and Loop or Loop and Inhiband in the duuration of this trial. It is submitted that the methodology detailed could, and probably should be used for future IUCD assessments.

A new abrasive applicator for human enamel biopsy procedures

Experiments were performed that demonstrated that the felt cylinder usually used to obtain abrasive biopsy specimens did not uniformly remove enamel from rounded or irregular enamel surfaces in the window area. A foam-silicone rubber laminate was developed to replace the felt cylinder. This resulted in greater uniformity of abrasion over the enamel surface within the biopsy window area and better operator handling characteristics.

Brain damage and associated behavioral deficits following the administration of L-cysteine to infant rats

L-cysteine in doses of 1.2-1.3 mg/g, was administered to 4-day-old rats which were tested throughout development and as adults on a variety of behavioral tasks. Lesions of the type previously described from L-cysteine treatment were confirmed in several cortical and limbic structures. No neurodegenerative changes were observed in NaCl (10 mmoles/kg) controls. Surviving L-cysteine treated animals displayed no obvious impairments in motor ability or growth rate, but did show behavioral deficits when tested as adults on 3 behavioral tasks: spontaneous alternation; Lashley III maze; and pattern discrimination. Activity in the open field was significantly higher in the L-cysteine group at 20 days of age. Amphetamine, administered in doses of 1.5 to 3.0 mg/kg, had no differential effects on open-field activity in the two groups. The behavioral changes observed in L-cysteine treated animals is similar to that which has been reported in adult rats with extensive hippocampal damage.