Biomedical subjects
Publications and source records attributed to J A Mangos.
A comprehensive system for the delivery of care to children with special healthcare needs and to their families has been developed by the department of pediatrics of The University of Texas Health Science Center at San Antonio. A description of the structure and operations of this system is presented and offered as a model for the state of Texas.
Lung infections are a major source of morbidity and mortality in recipients of lung transplants. Prominent among the pathogens that cause pneumonias in these subjects are gram-negative bacilli, particularly Pseudomonas strains. One important reason that bacteria infect the lungs of these patients is that pulmonary defenses are impaired by the drugs used to prevent transplant rejection. Using a rat alveolar macrophage cell line (NR8383), we measured the effects of exposure (24 hr) to cyclosporine and dexamethasone (DEX) on the ability of these cells to (1) kill Pseudomonas aeruginosa (Pa); (2) produce H2O2; and (3) release tumor necrosis factor. We found that the bactericidal activity against unopsonized or opsonized Pa of NR8383 cells was unaltered by CsA (0.1, 0.5, or 1 micrograms/ml), DEX (10(-6) M), or CsA + DEX (0.5 micrograms/ml + 10(-6) M, respectively). Likewise, LPS-induced TNF release, and zymosan A and Pa-induced H2O2 production were unaltered by CsA (0.1 or 1 microgram/ml). In contrast, H2O2 production and TNF release were decreased by about 50% and 90%, respectively, by DEX exposure (10(-6) M). Thus, while DEX but not CsA decreased TNF release and H2O2 production in NR8383 cells, bactericidal activity against Pa was unaffected. One explanation for these results is that decreases in TNF or H2O2 of the magnitude we observed do not impair bactericidal activity against Pa; however, an alternative explanation is that Pa are killed by NR8383 cells through other mechanisms. Interpretation of these results must take into consideration the fact that macrophages from different species and tissues may respond differently to various stimuli.
There is evidence that alveolar macrophages (AM) play a role in the clearing of Pneumocystis carinii from the lungs. To investigate the mechanisms involved in this process, we studied in vitro the induction of an oxidative burst by P. carinii in a cell line of macrophages (NR8383) and AM from normal rats. P. carinii was added to macrophage monolayers (10(6) cells), and the H2O2 produced after 4 h of incubation was measured. Both NR8383 macrophages and normal rat AM produced H2O2 in response to P. carinii cysts and trophozoites isolated from dexamethasone-treated rats, although the amount of H2O2 induced in AM from normal rats was larger. NR8383 macrophages bound and phagocytized both P. carinii cysts and trophozoites and produced increasing amounts of H2O2 as a dose-related response to cysts and trophozoites. Opsonization of P. carinii with normal rat serum increased H2O2 production by both types of macrophages; this enhancement was decreased, but not abolished, when the serum was first depleted of complement by heat treatment. These findings demonstrate that NR8383 macrophages and normal rat AM produce an oxidative burst in response to P. carinii and that this response is enhanced by complement.
The treatment of pediatric patients with HIV infection/AIDS is structured according to the clinical classification of the disease by the Centers for Disease Control; it involves prophylaxis, therapy against the human immunodeficiency virus, and therapy for the opportunistic infections and non-infectious complications of this disease. In spite of all these forms of therapy, the universal outcome of HIV infection/AIDS is the death of the patients. Prevention remains the only effective means to curb this epidemic.
For 9 years we have recognized HIV infection/AIDS as an unstoppable epidemic affecting infants, children, and adolescents as well as adults. Now we see the tremendous impact of this disease on the health systems of this country. During these past 9 years, we have witnessed the transformation of the epidemic from one primarily affecting male homosexuals to one invading the average US family through heterosexual and vertical transmissions and through needle-sharing practices of intravenous drug abuse. It has been estimated that 2% to 3% of the HIV infection/AIDS cases involve the pediatric age group. If 1.5 million Americans have HIV infection by 1991, as predicted, we should anticipate 30,000 to 45,000 infected pediatric patients by the end of that year. What has been the impact of this epidemic on the health systems involved in care, prevention, and research of pediatric HIV infection/AIDS? This article investigates that question.
In order to provide comprehensive care to infants, children, and adolescents with HIV infection/AIDS, a systematic approach to clinical management had to be developed. This approach involves "case management" by experienced health professionals, including initial evaluation and needs assessment, planning of services, brokerage of services, continuity of intervention until an outcome is reached. The care is delivered in hospitals, clinics, homes, residential facilities, respite care centers, and hospices. The care team needs to be multidisciplinary and well integrated.
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There is no question that the domain of the American family has been invaded by the HIV infection/AIDS epidemic. The disease, and particularly its form affecting children (pediatric AIDS), has had marked psychosocial impact on patients and families (intellectual/cognitive, emotional/behavioral, spiritual, and financial) and on our society in general (adverse or favorable). These impacts of pediatric AIDS are discussed in the present communication.
Sexual promiscuity often is part of the lifestyle of teenagers who are delinquent and abuse drugs, and that behavior puts them at increased risk of contracting HIV infection/AIDS. Many of these juveniles are runaways or live in disorganized homes, and as a result they are hard to reach and it is extremely difficult to provide health and other services to them. Indeed, these youths at risk most frequently may be identified and helped when they run afoul of the law and enter the judicial system. With that in mind, concerned professionals in San Antonio have developed an innovative program to provide primary care, drug abuse treatment and rehabilitation, and AIDS prevention education to the youthful offenders admitted to the Juvenile Detention Center of Bexar County. They hope it will give some of these youngsters the help and the opportunity they need to grow up, become productive citizens, and stay alive.
The Centers for Disease Control reported that 109,167 cases of AIDS had been diagnosed since 1981 and that approximately 40,000 persons were living with AIDS at the time of this writing. These numbers, however, are the tip of an iceberg that consists of approximately 1.5 million Americans who are infected by the human immunodeficiency virus (HIV). As we described in earlier articles of this series, the HIV infection/AIDS epidemic has invaded the domain of the American family through heterosexual transmission, vertical transmission, drug abuse, and sexual abuse of children. Therefore, physicians for children are now facing the prospects of having to deal with this disease in their practices. If there is something unique about pediatrics and other specialties of the medical profession dealing with infants and children, it is that "prevention" of disease can be and has been used effectively. One only needs to remember the 1950s, when the poliomyelitis epidemic was causing the same, if not greater, concerns in the lives of the American families. The development and application of the "polio" vaccines has virtually eliminated the threat of poliomyelitis in our society. Similarly, the incidence of diphtheria, tetanus, and smallpox has decreased to the point that these diseases present practically no threat to the US population. Armed with these positive experiences, we need to examine what we can do today to curb the spread of the HIV infection/AIDS among infants and children, and by extension, among the general population of our country.
Responses of a recently developed rat alveolar macrophage cell (NR8383.1) line were compared to those of freshly derived alveolar macrophages in vitro. Marked inter- and intraspecies heterogeneity in levels of phagocytosis of unopsonized Pseudomonas aeruginosa or zymosan was noted among freshly derived alveolar macrophages from rats, rabbits, and baboons. In contrast, phagocytic responses of alveolar macrophage cell line were predictable and highly reproducible. Similar results were obtained in measuring oxidative burst, as indicated by the production of H2O2 and luminol-enhanced chemiluminescence. Responses were again highly variable in freshly derived alveolar macrophages stimulated with zymosan or phorbol myristic acetate; moreover, freshly derived alveolar macrophages exhibited a wide range of chemiluminescence activity in unstimulated cultures. Results strongly suggest that data derived from the continuous alveolar macrophage culture NR8383.1 can be extrapolated to freshly derived alveolar macrophages of various species, and in many experiments will be useful in avoiding the significant animal-to-animal variance observed among freshly derived cell preparations.
The current epidemic of HIV infection/AIDS initially limited to homosexual males appears to be spreading through heterosexual transmission and intravenous drug abuse. Infants, children, and adolescents are affected. We examine the modes of transmission of HIV infection in this population and the impact the spreading of this infection in the pediatric age group will have on Texas.
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HIV infection/AIDS in infants and children under the age of 13 years expresses itself clinically so differently from the same infection in adults that a separate classification of the symptomatology has been adopted. Recurrent bacterial infections, as well as various opportunistic infections predominate, and while Kaposi's sarcoma is infrequent in pediatric patients, lymphomas occur with high frequency. The diagnosis of HIV infection/AIDS in children is presented.
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A unique, recently described rat alveolar macrophage cell line (NR8383) was used to study the interaction of the pulmonary immune system with a mucoid cystic fibrosis isolate of Pseudomonas aeruginosa (SRM-3), its nonmucoid revertant (SRM-3R), and a non-cystic fibrosis isolate (PAO-1). Strain SRM-3 was cultivated in a chemostat system to allow maintenance of an entirely mucoid population. The alveolar macrophage response to the mucoid and nonmucoid strains of P. aeruginosa was determined by visually quantitating phagocytosis in acridine orange-stained monolayers and measuring the induction of an oxidative burst as indicated by chemiluminescence and H2O2 production. In all experiments, fewer than 2% of the NR8383 cells engulfed the mucoid SRM-3 isolate, while SRM-3R and PAO-1 were phagocytized by 15 and 41%, respectively. Opsonization by normal serum (complement) provided minimal phagocytic enhancement of these strains, whereas specific anti-P. aeruginosa antibody slightly elevated phagocytic responses to strains with nonmucoid phenotypes while providing a sevenfold increase in uptake of SRM-3. Chemiluminescent and H2O2 responses were comparable with the levels of phagocytosis observed, with very little or no response to the mucoid strain SRM-3. The data indicate that the strains with mucoid phenotypes are refractile to ingestion and that studies which describe ingestion of mucoid strains were likely measuring ingestion of revertants. Alginic acid (2 mg/ml) was found to inhibit stimulation of macrophage response to the opsonized and unopsonized nonmucoid strain PAO-1.
A rat pulmonary alveolar macrophage (PAM) cell line (NR8383) was initiated in culture in the presence of a gerbil lung cell conditioned medium (GLCM), and has been propagated continuously for over 36 mo. When examined at different times throughout this in vitro period, NR8383 exhibited characteristics typical of macrophages: (a) Zymosan ingestion was seen in 90 to 98% of the cells examined; (b) Pseudomonas aeruginosa phagocytosis in 50 to 80%; (c) Nonspecific esterase activity in greater than 95%. During the first 6 mo., the PAM replicated with doubling times approximating 15 to 20 d. Throughout this period, GLCM dependence was evident. After 27 wk in vitro, NR8383 replication increased markedly, and within 2 wk, the doubling time was less than 48 h. NR8383 was readily monitored by [3H]thymidine (TdR) blastogenesis assay. In the presence of GLCM uptake of [3H]TdR was fivefold greater than in control cultures. Adherence and growth kinetics were effectively controlled by modulation of GLCM or serum content in culture medium. It was demonstrated that PAM growth factor(s) is ubiquitous, not species-specific, and under certain conditions may be derived from "endogenous" sources of persisting non-PAM populations within the parent, uncloned line NR8383. Cloned progeny remain devoid of non-PAM "feeder" cells, but retain macrophage properties, including interleukin-1 secretion, Fc receptors, and H2O2 production.
Gentamicin serum concentrations were measured in 15 children and seven adults with cystic fibrosis and in eight children with other diseases. Potentially toxic trough concentrations occurred in three of the first nine patients studied, in whom the dose and a 4-hour dosing interval were prescribed on the basis of one-compartment pharmacokinetic calculations (Sawchuck-Zaske method). In contrast, final concentrations were within the accepted target ranges for the remaining 13 patients with cystic fibrosis, in whom the dose and interval were adjusted empirically on the basis of a single pair of "peak" and trough values. The mean +/- SD final dosage required to achieve target concentrations was 13.8 +/- 2.9 mg/kg/d for children and 11.8 +/- 1.1 mg/kg/d for adults (P greater than 0.05), generally divided into four doses at 6-hour intervals. Mean half-life and incremental increase in serum concentration from previous trough to subsequent "peak," an indirect measurement of volume of distribution, were not significantly different between children or adults with cystic fibrosis and pediatric control subjects; there was little interpatient variability in these values. Thus the high dosage requirements were related more to the higher target concentrations than to altered pharmacokinetic disposition in patients with cystic fibrosis. We conclude that the initial dose of gentamicin to achieve a peak of 8 to 12 micrograms/mL and a trough of less than 2.0 micrograms/mL in patients with cystic fibrosis should be 3 mg/kg administered every 6 hours in children and every eight hours in adults. Subsequent dosage adjustment should be made on the basis of a pair of peak and trough serum concentration measurements obtained after the fifth dose. Dosing intervals in this patient population generally should be no shorter than every 6 hours, even if the initial trough concentration is less than 1 microgram/mL.