An animal model of hypersensitivity pneumonitis in the rabbit.

This study was devised to produce an animal model of hypersensitivity pneumonitis in order to study both the induction and the elicitation of the disease. Rabbits exposed by aerosol to large quantities of pigeon antigens developed a humoral, but not cellular, immunologic response. Moreover, their lungs were essentially normal histologically. A single i.v. injection of killed BCG in oil permitted the induction of pulmonary cell-medid hypersensitivity to the inhaled antigen, as well as the development of pulmonary lesions which were more severe than that caused by the administration of BCG alone. The humoral immunologic response to the inhaled antigen was not increased after BCG injection. Since many individuals are exposed to the etiologic agents of hypersensitivity pneumonitis for extended periods without developing the disease, these findings in animals suggest that some event may occur to induce cell mediated hypersensitivity in order to initiate the disease process. In addition, we have shown that animals with normal lung histology and circulating complement-fixing antibodies undergo serum complement (CH50) depression after an aerosol challenge with the specific antigen. Animals with circulating, complement-fixing antibodies, and inflamed lungs (BCG-induced failed to undergo a complement depression subsequent to an aerosol challenge with specific antigens. These results re consistent with those seen in symptomatic and asymptomatic pigeon breeders and suggest that antigen distribution through the lung is important in the pathogenesis of hypersensitivity pneumonitis.

Effect of hypersensitivity on protein uptake across the air-blood barrier of isolated rabbit lungs.

In previous studies with isolated perfused rabbit lungs, we observed that human serum albumin (HSA) and ovalbumin, introduced into the isolated lungs as an aerosol, entered the pulmonary circulation antigenically intact. The "inhaled" proteins were also broken down in the lung. When lungs from animals immunized with one protein inhaled the two proteins simultaneously, absorption of intact antigen was specifically reduced, and there was a nonspecific increase in the appearance of metabolites of both proteins in the blood. In the present study, we investigated the antigen-specific and nonspecific effects of two types of hypersensitivity responses on protein absorption across the air-blood barrier of isolated rabbit lungs. In one group of lungs, an acute hypersensitivity response was induced by introducing HSA into the blood perfusing lungs from HSA-immunized rabbits. In another, the rabbits had been previously exposed to chronic HSA aerosol until their lungs exhibited a chronic immunologic inflammatory response. Lungs from both groups were insufflated simultaneously with HSA, and a nonspecific protein, ovalbumin. Lungs in which the acute anaphylactic response was induced showed no alteration in the absorption of either intact protein compared with HSA-immunized controls, but absorbed a somewhat larger quantity of breakdown products of the specific antigen. Lungs undergoing the chronic alveolar inflammation were more permeable to nonspecific protein than were noninflamed lungs. Despite the increased permeability to nonspecific protein, the absorption of antigen was blocked as effectively as in immune but noninflamed controls. In these chronically inflamed lungs, the absorption of antigen breakdown products was enhanced. The results indicate that both immunologic and inflammatory mechanisms may control the amounts of inhaled soluble proteins that reach the blood via the alveolocapillary barrier. Alterations in the absorption of inhaled proteins and their metabolites across the air-blood barrier during certain types of hypersensitivity responses may be of immunologic and pathologic significance.

Absorption of inhaled antigen into the circulation of isolated lungs from normal and immunized rabbits.

The purpose of this study was to determine whether the absorption of inhaled antigen (Ag) across the pulmonary air-blood barrier of the isolated perfused lung can be modulated by immunologic mechanisms. Lungs from immunized or nonimmunized rabbits were removed, ventilated, and perfused with autochthonous blood. Radioiodinated Ag (human serum albumin or ovalbumin) was introduced as an aerosol into the isolated lung for 15 min and blood samples were taken over a 4-h period. The results showed that radioactivity fom inhaled Ag entered the perfusing blood as two fractions. One fraction was precipitable by 5% trichloroacetic acid or antiserum. The TCA-soluble fraction chromatographed differently from iodide and may have represented metabolites of the Ag. Immunization specifically reduced the amount of antigenically intact protein entering the blood. On the other hand, the metabolite reached higher concentrations in the blood of immunized lungs. We conclude that the alveolar capillary barrier of the normal rabbit lung could provide a significant route of entry for inhaled antigen into the systemic circulation and that immunization reduces absorption via this route and enhances pulmonary metabolism of the Ag.

Role of angiotensin-converting enzyme in Bacille Calmette-Guérin-induced granulomatous inflammation. Increased angiotensin-converting enzyme levels in lung lavage and suppression of inflammation with captopril.

Lung lavage levels of angiotensin-converting enzyme (ACE)-like activity were increased in C57BL/6 mice with Bacille Calmette-Guérin (BCG)-induced chronic granulomatous pulmonary inflammation and splenomegaly. Contrariwise, ACE activity was not increased in lung lavage fluids of CBA mice that developed only minimal pulmonary inflammation in response to BCG. ACE-like activity correlated with the intensity of inflammation and Captopril, a specific competitive inhibitor of ACE activity, markedly suppressed the induction and maintenance of the BCG-induced inflammatory response in both lungs and spleen. It was necessary, however, to provide sustained treatment with large doses of Captopril in order to reduce the inflammatory response. After a single intraperitoneal injection of Captopril, ACE levels in lung lavage of BCG-injected mice were reduced but returned to preinjection levels or greater within 24 h. The highest dose of Captopril was more effective in reducing the lung fluid level of ACE in BCG-inflamed lungs. This suggests that sustained daily injections of Captopril were necessary to maintain reduced ACE levels. In vitro studies indicated that high concentrations of Captopril did not affect macrophage mobility or chemotactic activity for macrophages. Thus, ACE may act as a molecular mediator of BCG-induced granulomatous inflammation in the lung.

Clinical needs assessment of middle and high school students following the 1995 Oklahoma City bombing.

OBJECTIVE: This clinical assessment was designed to identify middle and high school students in need of formal evaluation for posttraumatic response symptoms following the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City. METHOD: A clinical needs assessment instrument was developed and administered to grade 6 through 12 students 7 weeks after the bombing (N = 3,218). RESULTS: More than 40% of the students reported knowing someone injured, and more than one-third reported knowing someone killed in the blast. Posttraumatic stress symptoms at 7 weeks significantly correlated with gender, exposure through knowing someone injured or killed, and bomb-related television viewing. CONCLUSIONS: This study documents the intensity of community exposure to the bombing and the lingering symptoms of stress. The assessment was used in planning for clinical service delivery, training professional responders, and supporting funding requests.

Inhibition of stromelysin-1 (MMP-3) by P1'-biphenylylethyl carboxyalkyl dipeptides.

Carboxyalkyl peptides containing a biphenylylethyl group at the P1' position were found to be potent inhibitors of stromelysin-1 (MMP-3) and gelatinase A (MMP-2), in the range of 10-50 nM, but poor inhibitors of collagenase (MMP-1). Combination of a biphenylylethyl moiety at P1', a tert-butyl group at P2', and a methyl group at P3' produced orally bioavailable inhibitors as measured by an in vivo model of MMP-3 degradation of radiolabeled transferrin in the mouse pleural cavity. The X-ray structure of a complex of a P1-biphenyl inhibitor and the catalytic domain of MMP-3 is described. Inhibitors that contained halogenated biphenylylethyl residues at P1' proved to be superior in terms of enzyme potency and oral activity with 2(R)-[2-(4'-fluoro-4-biphenylyl)ethyl]-4(S)-n-butyl-1,5-pentane dioic acid 1-(alpha(S)-tert-butylglycine methylamide) amide (L-758,354, 26) having a Ki of 10 nM against MMP-3 and an ED50 of 11 mg/kg po in the mouse pleural cavity assay. This compound was evaluated in acute (MMP-3 and IL-1 beta injection in the rabbit) and chronic (rat adjuvant-induced arthritis and mouse collagen-induced arthritis) models of cartilage destruction but showed activity only in the MMP-3 injection model (ED50 = 6 mg/kg iv).

In vivo activity of human recombinant tissue inhibitor of metalloproteinases (TIMP). Activity against human stromelysin in vitro and in the rat pleural cavity.

Recombinant human tissue inhibitor of metalloproteinase (rhTIMP) suppressed the ability of native human stromelysin to degrade [3H]transferrin in vitro. Maximum inhibition occurred at molar ratios (TIMP: stromelysin) of 2:1 and 1:1. Reduced and alkylated tissue inhibitor of metalloproteinases (TIMP) lost its ability to suppress stromelysin activity. rhTIMP also inhibited stromelysin from degrading proteoglycan monomer in vitro. When injected into the rat pleural cavity prior to stromelysin, rhTIMP inhibited the ability of the enzyme to degrade aggregating cartilage proteoglycan monomer. Marked inhibition of stromelysin-mediated proteoglycan degradation in vivo occurred at molar ratios (TIMP: enzyme) of 2:1 and 1:1, with less inhibition at molar ratios of 0.5:1 and 0.25:1. Reduction and alkylation prevented rhTIMP from suppressing stromelysin-mediated degradation of proteoglycan monomer in vivo. By comparison, an equimolar concentration of the serine proteinase inhibitor, alpha 1-proteinase inhibitor (alpha 1-PI), did not inhibit stromelysin activity in the rat pleural cavity. This study demonstrates that rhTIMP is effective in inhibiting native human stromelysin both in vitro and in vivo.

Serum angiotensin-converting enzyme levels in patients with pigeon-breeder's disease.

The serum concentration of angiotensin-converting enzyme is frequently elevated in individuals with active sarcoidosis. The enzyme is presumably actively synthesized by the epithelioid and giant cells of the granuloma. Hypersensitivity pneumonitis, resulting from the inhalation of antigens from pigeons by susceptible individuals, is associated with the development of a granulomatous interstitial and alveolar infiltrate in the pulmonary parenchyma. Because the clinical and pathologic presentation may mimic that of sarcoidosis, we compared the serum levels of angiotensin-converting enzyme in these two diseases. The concentration of angiotensin-converting enzyme is not elevated in individuals with active hypersensitivity pneumonitis, in contrast to its frequent elevation in sarcoidosis. We suggest that the granulomatous response in hypersensitivity pneumonitis may differ at a biochemical level from that of sarcoidosis, since the synthesis of angiotensin-converting enzyme does not appear to be increased.

Posttraumatic stress responses in bereaved children after the Oklahoma City bombing.

OBJECTIVE: To investigate the responses of middle and high school students exposed to the 1995 Oklahoma City bombing across a spectrum of loss. METHOD: A questionnaire measuring exposure, personal consequences, initial response, and current posttraumatic stress and other symptoms was administered to 3,218 students 7 weeks after the explosion. RESULTS: More than one third of the sample knew someone killed in the explosion. Bereaved youths were more likely than nonbereaved peers to report immediate symptoms of arousal and fear, changes in their home and school environment, and posttraumatic stress symptoms. Retrospective measures of initial arousal and fear predicted posttraumatic stress symptoms at 7 weeks. CONCLUSIONS: The results support the literature addressing the role of initial response in posttraumatic stress symptom development. The study raises concern about the impact of television, and traumatized youths' reactivity to it, in the aftermath of disaster.

Flow cytometric DNA analysis of primary and concurrent metastatic squamous cell carcinoma of the head and neck.

Adequate flow cytometric DNA analysis comparing primary and concurrent metastatic squamous cell carcinoma of the head and neck has not been done in the past. The purpose of this study was to define any differences between the primary and concurrent metastasis of each patient with respect to flow cytometric parameters and histologic grade. Paraffin-embedded archival specimens from 28 patients with primary and metastatic tumors were prepared into nuclei and analyzed by flow cytometry using human lymphocyte standards. The mean DNA index was 0.82 for primary tumors and 0.83 for the metastases. Aneuploidy was found in 68 percent of primary tumors and in 82 percent of metastases. The percentage of cells in the proliferative fraction was 40.4 in the primary tumors and 24.5 in the metastases. A direct correlation was found between the differentiation of the primary and metastatic tumors. No survival difference was discovered among the flow cytometric parameters and histologic grade. We conclude that there is no difference between the primary and concurrent metastasis in squamous cell carcinoma of the head and neck with regard to DNA index, aneuploidy, or histologic grade.

Characteristics of pediatric firearm fatalities.

An increase in the awareness of the problem of gunshot fatalities in children has occurred nationwide over the last year. Unintentional firearm deaths are more common among children and young adults. These deaths may be addressed by preventive measures beyond those available for pediatric firearm suicide and homicide. This study focuses on the incidence of fatal gunshot injuries in children under 16 years of age during the years 1979 through 1987 in our state. Over the past 9 years 132 children (0 to 16 years) were shot and killed as a result of firearm injuries (M:F ratio, 3:1). No difference in absolute number in racial distribution existed. Deaths were classified as homicide, 61 (46%); accidental, 33 (25%); suicide, 29 (22%); undetermined, 7 (5%); and other, 2 (1.5%). Over 70% of these fatal injuries occurred in the home environment. Types of weapons involved included handguns (48%), shotguns (22%), rifles (17%), unspecified weapon (12%), and air rifle (1%). In a large number of cases, guns were found in the home unsecured. The perpetrator was known by the victim in 64 instances, while unknown in 27. Thirty-nine self-inflicted wounds and two shotgun blasts in the line of fire accounted for the remaining deaths. The most common anatomical injury and ultimate cause of death was cranial central nervous system (CNS) (62%), followed by chest/mediastinum (20%), abdomen (10%), and other (8%). A child who has sustained a firearm injury is more likely to know the perpetrator, be killed in the home by a readily available unsecured firearm, and die from severe head injury.

Surgical intervention in children with human immunodeficiency virus infection.

Twenty-one children with human immunodeficiency virus (HIV) infection required surgical intervention during the course of their disease. There were 11 females and 10 males (age range, 3 months to 6 years). The children underwent 54 operative procedures after diagnosis of their disease. These included placement of central venous catheter (23 patients), open lung biopsy (11), incision and drainage of perirectal abscess (4), incision and drainage of soft tissue abscess (5), myringotomy (2), diverting colostomy (3), Nissen fundoplication (1), and other (5). All 21 patients had clinical AIDS by the Centers for Disease Control CDC classification. To date, there have been 12 deaths in the 21 patients (57%) due to progressive deterioration with the patient's disease. Most procedures were adjuncts for diagnostic and therapeutic intervention in a population of children with a uniformly fatal disease. The knowledge of various high risk groups for AIDS must heighten the surgeon's awareness to the growing and significant pediatric segment of the HIV population, the complications of their disease, and the surgeon's limited role in treating these problems.

Does handgun legislation change firearm fatalities?

When comparing firearm fatalities for children under 16 years of age before and after handgun legislation enactment in Maryland, firearm fatalities increased overall. A decrease in accidental deaths in the home perhaps reflects a response to public education and awareness. More aggressive handgun legislation is imperative to reverse this public health trend.

The role of exposure in posttraumatic stress in youths following the 1995 bombing.

This study investigated the relative impact of various forms of exposure to the 1995 Oklahoma City bombing in middle and high school students seven weeks after the incident. We assessed 3210 youths with an instrument that probed for physical, television, and emotional exposure to the bombing and subsequent posttraumatic stress symptomatology and television reactivity. The majority of youths were exposed through physical proximity--hearing and/or feeling the blast--and through television viewing. These types of exposure, as well as emotional exposure, constituted important variables in the development of posttraumatic stress symptoms and television reactivity. Youths with immediate family casualties were more symptomatic than those without.