Sex Differences Distinguish Intracortical Glutamate Receptor-Mediated Regulation of Extracellular Dopamine Levels in the Prefrontal Cortex of Adult Rats.

Executive functions of the prefrontal cortex (PFC) are sensitive to local dopamine (DA) levels. Although sex differences distinguish these functions and their dysfunction in disease, the basis for this is unknown. We asked whether sex differences might result from dimorphisms in the glutamatergic mechanisms that regulate PFC DA levels. Using antagonists selective for α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptors, we compared drug effects on in vivo microdialysis DA measurements in the PFC of adult male and female rats. We found that baseline DA levels were similar across sex, AMPA antagonism decreased PFC DA in both sexes, and NMDA antagonism increased DA in males but decreased DA in females. We also found that, at subseizure-producing drug levels, γ-aminobutyric acid (GABA)-A antagonism did not affect DA in either sex but that GABA-B antagonism transiently increased PFC DA in both sexes, albeit more so in females. Finally, when NMDA antagonism was coincident with GABA-B antagonism, PFC DA levels in males responded as if to GABA-B antagonism alone, whereas in females, DA effects mirrored those induced by NMDA antagonism. Taken together, these data suggest commonalities and fundamental differences in the intracortical amino acid transmitter mechanisms that regulate DA homeostasis in the male and female rat PFCs.

Interrelationships between the human alveolar macrophage and alpha-1-antitrypsin.

Alveolar macrophages lavaged from human lungs contain protease activity at an optimum pH of 3.0 and possibly a lesser peak of activity at pH 5.5. Protease activity measured at pH 4.1 is inhibited by purified alpha-1-antitrypsin. Fluorescent antibody studies of human alveolar macrophages showed that alpha-1-antitrypsin is present in normal alveolar macrophages. In addition, macrophages from a patient with a homozygous deficiency of alpha-1-antitrypsin exhibited less fluorescence when incubated in autologous serum than the same macrophages incubated in normal serum. Macrophages from normal subjects showed maximal fluorescence when removed from the lung and additional incubation with serum did not increase fluorescence. These results implicate the human alveolar macrophage as a possible source of an enzyme that may cause emphysema in patients deficient in alpha-1-antitrypsin. They also show that alpha-1-antitrypsin has access to the alveolus in normal subjects.

Mechanism of inhibition of porcine elastase by human alpha-1-antitrypsin.

The interaction of the human plasma protein, alpha-1-antitrypsin, with porcine pancreatic elastase was studied by isolating and characterizing their reaction products. Native alpha-1-antitrypsin has a mass ratio (Mr) of 54,000, an amino-terminal glx, and a carboxy-terminal lys residue. The elastase used has an Mr of 26,400 and an amino-terminal val residue. When the two proteins are combined at inhibitor excess, two major products result. One of the products is a complex of the enzyme and inhibitor with amino-terminal ser and val residues, which indicates that a peptide has been removed from the amino-terminal end of the inhibitor. The second product is a modified form of alpha-1-antitrypsin with an Mr of 51,300, an aminoterminal glx residue and a carboxy-terminal thr-leu dipeptide. It has no inhibitory activity against elastase. The components of the isolated complex can be split at high pH in the presence of diisopropyl fluorophosphate, which results in a catalytically inactive enzyme with the same Mr and amino-terminal residue as the native enzyme, and a large fragment of alpha-1-antitrypsin (alpha-1-antitrypsin(*)). This fragment has an Mr of 50,100, an amino-terminal ser residue and a carboxy-terminal thr-leu dipeptide. Based on these data, the following hypothesis is proposed. Elastase can attack alpha-1-antitrypsin at either of two major sites. If it attacks first at the carboxy side of the thr-leu dipeptide, located in the carboxy-terminal portion of the inhibitor, the alpha-1-antitrypsin is cleaved into two fragments with loss of inhibitory activity and absence of complex formation. If, however, the elastase first attacks an x-ser bond near the amino-terminal end of the inhibitor, the elastase then reacts with alpha-1-antitrypsin at the same leu moiety to form a stable complex with complete inhibition of the enzyme.

The human alveolar macrophage: isolation, cultivation in vitro, and studies of morphologic and functional characteristics.

Human alveolar macrophages were lavaged from surgically resected lungs and from lungs of normal subjects. Macrophages that had been purified by glass adherence were maintained in tissue culture for as long as 54 days. After 3-4 wk in vitro they underwent transformation into multinucleated giant cells. These aged cells had more than 30 times the phagocytic capacity that the same group of cells had had after 1 day in vitro. Phagocytosis of heat-killed Candida albicans was inhibited by iodoacetate, sodium fluoride, potassium cyanide, and low partial pressures of oxygen, suggesting that these cells require both oxidative and glycolytic energy sources for maximal particle ingestion. Alveolar macrophages and monocyte-derived macrophages killed Listeria monocytogenes with similar efficiency, but neutrophils were more efficient than either of the other cell types. Bacterial killing is probably not dependent upon myeloperoxidase in the monocyte-derived macrophage or in the alveolar macrophage since histochemical stains for peroxidase do not stain either cell type. C. albicans blastospores, which are killed by neutrophils and monocytes that contain myeloperoxidase, were not killed by human alveolar macrophages during the 4 hr of observation. Large cells with supernormal phagocytic capacity were recovered from patients with postobstructive pheumonia and from one patient with recurrent bacterial pneumonia, indicating that macrophage function can be altered in certain disease states. Human alveolar macrophages are unique human phagocytes in their dependence on an oxygen tension greater than 25 mm HG for maximal phagocytosis. Carbon dioxide tensions as high as 70 mm Hg did not alter phagocytosis when the pH of the medium was held constant. These data suggest that the increased susceptibility to pneumonia of patients with chronic bronchitis or atelectasis may be in part related to suboptimal phagocytosis by macrophages in areas of the lung with depressed oxygen tension.

Neutrophil turnover in normal rabbit lungs.

Neutrophil turnover was studied in the blood and alveoli of normal rabbits. Blood neutrophil turnover was examined by two different methods. In the first method, donor rabbit neutrophils were labeled in vivo by injecting tritium-labeled thymidine intravenously. After 72 h recipient rabbits received blood from the donors. The decline of the specific radioactivity of blood neutrophils was used to determine that their half-life was 4.03 h. In the second method, rabbit peritoneal exudative neutrophils were elicited with oyster glycogen. These cells were labeled with 111Indium oxine and infused into the blood of recipient animals. By their decline in specific radioactivity, the half-life of the blood neutrophil was 4.08 h. These half-lives are not significantly different. Lung lavage was performed on the animals that received the 111Indium-labeled neutrophils and the turnover time of the lung neutrophil was found to be 2.63 h. The turnover of the alveolar neutrophil pool accounted for only 0.19% of the total turnover of the blood neutrophils. Therefore, the lung appears to contribute only minimally to the total capacity of the body to dispose of neutrophils.

Studies on the pathogenesis of the adult respiratory distress syndrome.

Bronchoalveolar lavage (BAL) fluid was obtained from 24 sequentially studied patients with adult respiratory distress syndrome (ARDS) for assessment of potential activating and mediating factors. Proteolytic activity of the fluids was observed by measuring cleavage of radiolabeled proteins of the contact (Hageman factor) and complement systems. Proteolytic activity was observed in 17 of 24 (71%) patients with ARDS, and BAL fluid of the 7 ARDS patients without demonstrable, active, enzyme exhibited inhibitory activity for the proteolytic activity. The enzymes cleaved Hageman factor, prekallikrein, plasminogen, high molecular weight kininogen, C4, C3, C5, and Factor B of the complement system. Cleavage of the contact system proteins producted fragments similar or identical in size to the fragments observed during activation of these molecules, although continued incubation invariably reduced the protein to small peptide fragments. None of 7 normal individuals, and 29 of 99 patients (29%) with other forms of pulmonary disease contained measurable enzymes. The proteolytic activity in BAL fluid of ARDS patients was blocked by diisopropylphosphofluoridate (0.1 mM), Trasylol, soybean trypsin inhibitor, and normal plasma, or plasma deficient in inhibition of the first component of complement. Alpha(1)-proteinase inhibitor (alpha1-PI)-deficient plasma failed to inhibit the proteolytic activity and addition of alpha1-PI to the deficient plasma reconstituted the inhibition. MUCH OF THE PROTEOLYTIC ACTIVITY OF THE BAL FLUID FROM ARDS PATIENTS WAS IDENTIFIED AS NEUTROPHIL ELASTASE: the fluids cleaved elastin and synthetic peptide substrate of neutrophil elastase, neutrophil elastase antigen was present in the BAL fluids as determined immunologically using antineutrophil elastase, alpha1-PI was the major inhibitor in plasma, and the enzyme was inhibited by diisopropylphosphofluoridate but not chelation. In addition, purified neutrophil elastase produced cleavage fragments of proteins of the contact system similar to those of the BAL fluids. In each of the seven BAL fluids of ARDS patients that did not reveal active elastase, alpha1-PI was present in active form (as determined by (125)I-trypsin binding). In 9 of the 17 patients with active elastase in the BAL fluid, alpha1-PI antigen was present in the fluid, but was inactive (no binding of (125)I-trypsin). Immunoelectrophoretic analysis of elastase and alpha1-PI throughout proteins in these BAL fluids revealed the presence of both elastase and alpha1-PI that migrated with the same R(f), suggesting the presence of an enzyme-inhibitor complex. Free, inactive alpha1-PI was also observed in these fluids. The data reveal that in BAL fluids from all 24 patients with ARDS, leukocytic elastase and/or alpha1-PI exist. A complex of elastase and alpha1-PI was observed in BAL fluids, and in some cases where active enzyme and alpha1-PI coexisted, free, but inactive alpha1-PI was present.

A model of decreased functional alpha-1-proteinase inhibitor. Pulmonary pathology of dogs exposed to chloramine T.

The objective of this study was to develop an animal model representative of chronic human alpha-1-proteinase inhibitor deficiency. Eight dogs were treated with a mild oxidizing agent, chloramine T, with varying regimens for 3--27 wk. The capacity of the serum to inhibit both trypsin and elastase was examined and found to respond differently. Although immunologically determined levels of protease inhibitor did not change, the ability of serum to inhibit elastase in an in vitro assay decreased in direct response to chloramine T treatment. The trypsin inhibitory capacity was less affected. Emphysemalike alterations in lung morphology were observable when histologic sections were evaluated both subjectively and objectively by mean linear intercept measurements. The data suggest that this model parallels the emphysema associated with the genetic alpha-1-proteinase inhibitor deficiency in man.

Inactivation of factor XIa by plasma protease inhibitors: predominant role of alpha 1-protease inhibitor and protective effect of high molecular weight kininogen.

Factor XIa is a plasma protease that, by activating Factor IX, plays an important role in the early phase of the intrinsic pathway of blood coagulation. Four plasma protease inhibitors, alpha(1)-protease inhibitor, antithrombin III, C1-inhibitor, and alpha(2)-plasmin inhibitor, have been reported to inactivate human Factor XIa, but their quantitative contribution to the inactivation of Factor XIa in plasma has not been fully assessed. Using purified systems, we observed that the second-order rate constants for the reaction of Factor XIa with alpha(1)-protease inhibitor, antithrombin III, and CI-inhibitor were 4.08, 10, and 14.6 M(-1) min(-1) x 10(3), respectively. The pseudo-first-order rate constants, at plasma concentration of the inhibitors, were 1.86 x 10(-1), 4.68 x 10(-2), and 2.4 x 10(-2) min(-1), respectively. These kinetic data predict that alpha(1)-protease inhibitor should account for 68%, antithrombin III for 16%, and C1-inhibitor and the equipotent alpha(2)-plasmin inhibitor each for 8% of the total inhibitory activity of plasma against Factor XIa. The rate of inactivation of Factor XIa in various plasma samples specifically deficient in inhibitors was consistent with these predictions. Factor XI, the zymogen form of Factor XIa, circulates in plasma associated with the contact system cofactor, high molecular weight kininogen (HMW kininogen). Kinetic analysis indicated the existence of a reversible bimolecular Factor XIa-HMW kininogen complex with a dissociation constant (K(d)) = 0.17 muM. The light chain derived from HMW kininogen decreased the inactivation rate of Factor XIa by C1-inhibitor with a K(d) of 0.08 muM for a complex of Factor XIa and the light chain derived from HMW kininogen. The protective effect of HMW kininogen was confirmed by the finding that the inactivation rate of Factor XIa in kininogen-deficient plasma was increased over normal plasma. The present study confirms that alpha(1)-protease inhibitor is the major inhibitor of Factor XIa in plasma, and that the formation of a reversible complex between Factor XIa and HMW kininogen decreases the rate of inactivation of the enzyme by its inhibitors.

A unique elastase in human blood platelets.

Previous investigations suggested that elastolytic activity found in platelets could be due to contamination by neutrophil elastase. In the present study, the lysate of blood platelets free of detectable neutrophils was examined for elastase-like activity using tertiary-butyloxycarbonyl (tBOC)-ala-ala-pro-ala-aminomethyl coumarin (I), tBOC-ala-ala-pro-val-aminomethyl coumarin (II), and succinyl-tri-ala-rho-nitroanilide (SAPNA), and for elastolytic activity using 3H-labeled dog and human lung elastins. The platelet lysate degraded I at a higher rate than II, while the reverse was true of neutrophil elastase. The rate of degradation of I, II, and SAPNA by the lysate increased with reaction time up to 20 min. The rate of I, II, and SAPNA degradation by the lysate was decreased by the presence of 0.5 M NaCl, whereas NaCl greatly potentiated their degradation by neutrophil elastase. Plasma alpha 2-macroglobulin inhibited elastolysis by the platelet lysate, whereas plasma alpha 1-antitrypsin did not. The lysate activity was inhibited by diisopropyl fluorophosphate, phenylmethylsulfonyl fluoride, elastatinal, Trasylol, and furoyl-saccharin. The optimum pH for platelet lysate activity was 8.5-9.0, as in other studies using elastin as substrate. The pH 4.5 eluate obtained after incubation of the lysate with dog lung elastin at neutral pH exhibited the same catalytic properties as the activity in the lysate. The different substrate and inhibitor specificities and the failure of IgG specific for neutrophil elastase to remove elastase-like and elastolytic activities from the lysate indicate that a unique elastase occurs in platelets.

A synthetic peptide inhibitor for alpha-chemokines inhibits the growth of melanoma cell lines.

Melanoma growth stimulatory activity (MGSA/GROalpha) is a 73 amino acid peptide sharing sequence characteristics with the alpha-chemokine superfamily. MGSA/GROalpha is produced by diverse melanoma cell lines and reported to act as an autocrine growth factor for the cells. We tested the binding of MGSA/GROalpha to melanoma cell lines, Hs 294T and RPMI7951, and found that these cells could bind to MGSA/GROalpha but not to interleukin-8. Recently, we defined a novel hexapeptide, antileukinate, which is a potent inhibitor of binding of alpha-chemokines to their receptors on neutrophils. When antileukinate was added to melanoma cells, it inhibited the binding of MGSA/ GROalpha. The growth of cells from both melanoma cell lines was suppressed completely in the presence of 100 microM peptide. The cell growth inhibition was reversed by the removal of the peptide from the culture media or by the addition of the excess amount of MGSA/GROalpha. The viability of Hs 294T cells in the presence of 100 microM peptide was > 92%. These findings suggest that MGSA/GROalpha is an essential autostimulatory growth factor for melanoma cells and antileukinate inhibits their growth by preventing MGSA/GROalpha from binding to its receptors.

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.

The interaction of alpha-1-antitrypsin with chymotrypsin, trypsin and elastase.

The mode of inhibition by alpha-1-antitrypsin of chymotrypsin, trypsin and pancreatic elastase was examined by a kinetic method. All three enzymes were completely bound to alpha-1-antitrypsin; therefore, the dissociation constant of the enzyme-inhibitor complex was too low to measure with these methods. The dissociation constants for the three enzyme-inhibitor complexes were estimated to be less than 5 - 10 minus 9 M. However, alpha-1-antitrypsin could be specifically displaced from Sepharose-bound elastase with an irreversible inhibitor of that enzyme. Additional experiments showed that dioxane, 20% (v/v), blocked 100% of the inhibition of elastase, 16% of the inhibition of trypsin, and 0% of the inhibition of chymotrypsin. The effect was reversed by diluting the dioxane to 1% (v/v). These findings indicated that alpha-1-antitrypsin was tightly bound to the three enzymes studied but did not allow discrimination as to the nature of the inhibition. However, the competitive mode of inhibition was suggested by the displacement of alpha-1-antitrypsin from elastase by an irreversible inhibitor of the enzyme that bound covalently at the enzyme-active site. The variable susceptibility of the enzyme to blockage of the inhibition by low concentrations of p-dioxane suggested that hydrophobic bonds may be important in the interaction with alpha-1-antitrypsin.

Low pH stability of alpha-1-antititrypsin.

According to the previous findings of others, the trypsin inhibitory capacity of alpha-1-antitrypsin is irreversibly lost in acidic solutions below pH 5.0. In contrast, experiments reported herein show that considerable inhibitory activity can be regenerated as a time-dependent phenomena following titration to basic media. The rate of recovery of activity is accompanied by a decreasing amplitude in the fluorescent emission spectrum at 335 nm of acidified alpha-1-antitrypsin solutions following adjustment to pH 8.0. Acidic media also results in the slow, progressive formation of protein aggregates as measured using Sephadex gel filtration. This latter process is more prominent at pH 4.0, near the isoelectric point of alpha-1-antitrypsin than at pH 3 or 2. Both monomer and polymeric forms of alpha-1-antititrypsin were isolated before or after adjustment to basic media. Isolated monomeric material shows a high recovery of biological and immunological activity; aggregate forms, however, are immunologically cross-reactive but show little enzyme inhibitory activity.

The interaction of alpha-1-antitrypsin with soluble and sepharose-bound elastase.

The products resulting from the interaction of alpha-1-antitrypsin with elastase were examined with polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate, and by affinity chromatography. Five products of the reaction can be identified by polyacrylamide disc gel electrophoresis. Two products are complexes between alpha-1-antitrypsin and elastase (73 800 and 58 300 daltons). Two additional products are identical to fragments of alpha-1-antitrypsin which can be washed from a column of Sepharose-bound elastase immediately after alpha-1-antitrypsin is applied to the column. The larger component about 50 000 daltons, reacts with antiserum to alpha-1-antitrypsin, and does not inhibit enzymes. Together, these two products have an amino acid analysis similar to alpha-1-antitrypsin. These two fragments are probably hydrolytic products of the interaction of elastase with alpha-1-antitrypsin which is biologically inactive. The fifth product is probably a fragment of alpha-1-antitrypsin missing from the low molecular weight complex. The components of the complexes can be separated from each other by a mild nucleophilic attack. Small quantities of alpha-1-antitrypsin can be displaced from the elastase affinity column by phenyl methane sulfonyl fluoride. In conclusion, porcine pancreatic elastase forms two complexes with alpha-1-antitrypsin. One or both complexes can be split by alkali.

Management strategies for urinary and vaginal infections.

Detailed history, physical examination, laboratory and follow-up data were obtained from 821 women coming to a primary care clinic over a two-year period with the symptoms of urinary tract (UTI) or vaginal infection. Using all available information, each patient retrospectively was given one of several mutually exclusive diagnoses. Vaginitis without UTI was diagnosed in 70% of patients, UTI without vaginitis in 12%, UTI and vaginitis in 2%. The conditional probability of the several possible diagnoses was calculated, given various combinations of clinical data; a diagnosis of vaginitis was twice as likely as a diagnosis of UTI in a patient with dysuria. On the basis of these calculations we identified efficient clinical strategies for when to perform a pelvic examination, a urinalysis, and a urine culture, and when to diagnose UTI presumptively on the basis of urinalysis.

Health reform lessons learned from physicians in three nations.

To explore the concerns of practicing physicians as a way to inform the health reform debate, the authors conducted a survey of physicians in the United States, Canada, and Germany. Survey results indicate that U.S. physicians are most likely to view affordability as the greatest barrier to access to care for their patients. However, unavailability of services and long waiting times were cited most often by Canadian physicians. German physicians did not cite access problems as frequently as Canadian physicians did; other measures of satisfaction were closer to U.S. levels, suggesting fewer trade-offs if the United States were to adopt aspects of the German health care system.

Bronchoalveolar lavage in patients with the adult respiratory distress syndrome.

BAL in patients with ARDS provides material containing the soluble and cellular constituents of the alveolar compartment, and hence is a useful tool for the study of the pathogenesis of ARDS. The technique is imperfect as it is prone to problems of data acquisition and interpretation. However, it is lung-specific and may be used in serial studies of patients over the course of their disease. A large amount of evidence is rapidly being accumulated which documents the presence of effectors of inflammation in the BAL fluids of patients with ARDS. Confirmation of the importance of such mediators, pathways, or cellular constituents of BAL fluid in establishing the pathogenesis of ARDS ultimately depends upon proof of the efficacy of specific clinical interventions which both arrest the activity of the effector and predictably alter the course of the disease.

Young physicians most and least likely to have second thoughts about a career in medicine.

To identify factors associated with apparent disaffection with medicine as a career, the authors analyzed data for 4,931 young physicians surveyed in 1987. Using survey responses, the authors classified 932 of the physicians (18.9%) as most likely to have second thoughts about their career choices and 1,094 (22.2%) as least likely to have second thoughts. The group with the greatest reservations included significantly higher proportions of white women, blacks, and Hispanics. This group reported significantly lower incomes, higher educational debt, and more hours and patients' visits per week. Among employee physicians, those most disaffected were significantly more likely to report inappropriate use of tests and procedures and lack of autonomy in their practices. The authors conclude that it is important to reexamine the heavy reliance on debt financing of medical education, especially for minority students, and to explore the equality of career opportunities for women and minorities in medicine.

Religion and the morality of mentality.

Christian doctrine considers mental states important in judging a person's moral status, whereas Jewish doctrine considers them less important. The authors provide evidence from 4 studies that American Jews and Protestants differ in the moral import they attribute to mental states (honoring one's parents, thinking about having a sexual affair, and thinking about harming an animal). Although Protestants and Jews rated the moral status of the actions equally. Protestants rated a target person with inappropriate mental states more negatively than did Jews. These differences in moral judgment were partially mediated by Protestants' beliefs that mental states are controllable and likely to lead to action and were strongly related to agreement with general statements claiming that thoughts are morally relevant. These religious differences were not related to differences in collectivistic (interdependent) and individualistic (independent) tendencies.