Biomedical subjects

J C Waldrep

Publications and source records attributed to J C Waldrep.

At least 37 records · Page 2Linked to original sources

PubMed1998

Regional lung deposition and clearance of 99mTc-labeled beclomethasone-DLPC liposomes in mild and severe asthma.

OBJECTIVE: To compare the distribution and clearance of inhaled beclomethasone dipropionate (Bec)-dilauroylphosphatidylcholine (DLPC) liposomes in patients with mild and severe asthma. DESIGN: A 99mTc-labeled Bec-DLPC suspension was delivered via a nebulizer (Aerotech II). Immediately after inhalation, anterior and posterior views of the lungs and an anterior view of the oropharynx were measured by a large field gamma camera with the patient in a supine position. To evaluate the mucociliary clearance of the inhaled liposomes, anterior and posterior lung scans were repeated 1, 2, 4, and 24 h after the aerosol delivery. PATIENTS: Ten patients with mild asthma (FEV1 >80% of the predicted) and 10 patients with severe asthma (FEV1 <60% of the predicted) were included in an open, parallel group study. RESULTS: Clearance is more rapid among patients with severe asthma (p<0.0001). At the 4-h measurement, a mean of 82% (SD, 5.9) of the total pulmonary dose was detected in the lungs of patients with mild asthma while in those with severe asthma the figure was 69% (SD, 10.9). The ratio between central and peripheral deposition was significantly higher for patients with severe asthma than for those having a mild form of the disease; 1.07 (SD, 0.29) and 0.76 (SD, 0.07), respectively (p=0.008). CONCLUSIONS: Inhaled Bec-DLPC liposomes were deposited more centrally in the lower airways of patients with severe asthma than those having a milder form of the disease. The clearance of Bec-DLPC liposomes is strikingly slow in both groups of asthmatic patients. However, due to the more peripheral penetration of inhaled liposomes in patients with mild asthma, the clearance rate in this group was slower than in those with severe asthma.

Administration, Inhalation↗

PubMed1998

Four hours of continuous albuterol nebulization.

BACKGROUND AND OBJECTIVES: Continuous albuterol nebulization (CAN) is a therapeutic modality available to treat status asthmaticus. Currently, CAN may be administered using a large-volume nebulizer (LVN) or a small-volume nebulizer attached to an infusion pump or refilled as needed. Few data are available regarding the reproducibility of aerosol characteristics during CAN. In this study, we determined the aerodynamic profile, drug output (DO), DO in respirable range (RD), solution output (SO), and changes in reservoir's albuterol concentration (AR) hourly during 4 hours of CAN. DESIGN: A modified Puritan-Bennett 1600 jet nebulizer was tested with a large reservoir (LR; 250 mL), medium reservoir (MR; 45 mL), and small reservoir with infusion pump (SRP; 18 mL). We used 100-, 40-, and 4-mL initial fill volumes (with 10-mL/h infusion for SRP) of 1 mg/mL albuterol solution for the LR, MR, and SRP, respectively. Particle size distribution and DO consistency were determined by impaction and spectrophotometric analysis (275 nm). We also determined albuterol mass output. The SO was determined by gravimetric technique. RESULTS: The PBsj produced a heterodisperse aerosol with a median mass aerodynamic diameter range of 1.8 to 2.2 microm. DO and RD paralleled SO. The LR had the highest SO, DO, and RD (8.03+/-2.36 vs 5.73+/-2.48 and 5.85+/-0.51 mg/h for MR and SRP, respectively). The AR showed no statistically significant changes. CONCLUSIONS: The PBsj demonstrated consistent and adequate aerosol production during 4 hours of CAN. These bench data support the widespread use of a LVN for CAN.

Adrenergic beta-Agonists↗

PubMed1997

Nebulized interleukin 2 liposomes: aerosol characteristics and biodistribution.

Although interleukin 2 (IL-2) has been associated with modest anti-tumour responses in man, treatment-related toxicity has limited its widespread use. The local delivery of liposomal formulations of interleukin 2 to the lung as aerosols has been demonstrated to be non-toxic, biologically active, and associated with regression of spontaneous pulmonary metastases in dogs. This study was undertaken to evaluate the physical and biological characteristics of nebulized interleukin 2 liposomes. The aerosol droplet size distribution and the physical stability of interleukin 2 liposomes were examined in-vitro using an Andersen cascade impactor and studies of liposome entrapment of interleukin 2 before and after nebulization. The biological stability of interleukin 2 liposomes after nebulization was demonstrated using the CTLL-2 bioassay for interleukin 2. In-vivo studies of pulmonary biodistribution and clearance of inhaled technetium (99mTc)-labelled interleukin 2 liposomes were undertaken in a normal dog. Aerosols of free interleukin 2 and of interleukin 2 liposomes were compared in both in-vitro and in-vivo experiments. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of interleukin 2 liposomes were 1.98 microns and 2.02, respectively. Independent analysis of aerosol particle-size distribution using the constitutive components of the interleukin 2 liposomes (interleukin 2: lipid:HSA) demonstrated a close correlation of size distributions (r = 0.9445; P < 0.001). The entrapment of interleukin 2 in liposomes was 93 +/- 4.3% before nebulization and 90 +/- 8.9% after. After delivery to an anaesthetized dog, interleukin 2 liposome aerosols were deposited evenly throughout the lung (mean +/- s.d. central lung-to-peripheral lung deposition was 1.12 +/- 0.03). After approximately 24 h inhalation, interleukin 2 liposomes were retained within the lung and were taken up in part by the spleen. The results of this study are indicative of the stability of this interleukin 2 liposome formulation to nebulization. Such nebulization might be an attractive immunotherapeutic strategy for treatment of pulmonary metastases and primary lung cancers.

Aerosols↗

PubMed1997

Pulmonary delivery of beclomethasone liposome aerosol in volunteers. Tolerance and safety.

STUDY OBJECTIVE: To test the tolerance and safety of single doses of beclomethasone dipropionate (Bec)-dilauroylphosphatidylcholine (DLPC) liposome aerosol in volunteers. DESIGN: Single-dose inhalations of liposome preparations of Bec-DLPC and DLPC alone were administered for 15 min from a jet nebulizer (Puritan-Bennett, modified twin jet; mass median aerodynamic diameter of 1.6 microns) under close clinical and laboratory surveillance. Two dose levels (0.5 mg Bec/12.5 mg DLPC per milliliter, and 1.0 mg Bec and 25 mg DLPC per milliliter in the reservoirs, respectively) were administered. The Bec doses were selected to approximate the dosages of this glucocorticoid used with metered-dose inhalers (MDIs). First, four volunteers were exposed to an initial low dose; the mean (+/-SD) inhaled doses were 0.56 +/- 0.07 mg of Bec and/or 14.0 +/- 1.8 mg of DLPC. Subsequently, a second group of six volunteers was exposed to a higher dose; the mean (+/-SD) inhaled doses were 1.29 +/- 0.14 mg of Bec and/or 34.6 +/- 6.8 mg of DLPC. SETTING: Outpatient and inpatient. PATIENTS: Normal male (n = 6) and female (n = 4) adult volunteers. INTERVENTIONS: Inhalation of Bec-DLPC and DLPC liposome aerosols in a single-dose tolerance study involving 10 normal volunteers. MEASUREMENTS AND RESULTS: Spirometry, clinical observations, clinical chemistry, and hematology were monitored. No adverse clinical or laboratory events were observed. CONCLUSIONS: Bec-DLPC liposome aqueous aerosol was well tolerated in doses equivalent to those currently administered by MDIs and dry powder inhalers for treatment of asthma.

Adult↗

PubMed1996

Delivery of DNA-cationic liposome complexes by small-particle aerosol.

Aerosol delivery of gene therapy for treatment of lung diseases allows topical treatment of the airways with DNA concentrations not obtainable by systemic administration. We have investigated delivery of cationic liposomes complexed to plasmid DNA in a small particle aerosol. Plasmid cDNA-DMRIE/DOPE complexes were nebulized using either an Aerotech II or Puritan-Bennett 1600 (PB1600) nebulizer. Reservoir sampling showed that DNA-DMRIE/DOPE complexes were damaged to a significant degree during nebulization, such that activity of transfected gene was diminished. Of the nebulizers analyzed, DNA-DMRIE/DOPE complexes were more stable in the PB1600. The loss of effective transfection by DNA-DMRIE/DOPE, as detected by decreased reporter gene activity in A549 lung cells, was consistent with denaturation of the DMRIE/DOPE. In contrast, nebulized DNA-DOSPA/DOPE complexes retained complete ability to transfect. Adjustments to flow rate and reservoir volume of the PB1600 allowed a longer period of delivery of active DNA-DMRIE/DOPE particles. DNA-DMRIE/DOPE was radiolabeled with Technetium-99m (99mTc), nebulized, and the output captured in either an Andersen Sampler (AS) (Andersen, 1958) cascade impactor particle size analyzer or an all glass impinger. cDNA-cationic lipid complexes were detected in size ranges of 0.4-10 microns, with most particles found between 1-2 microns. Aerosol output was consistent from 0 to 5 min. These results show the feasibility of aerosol delivery of DNA-cationic lipids for the purposes of gene therapy to the lung.

Aerosols↗

PubMed1994

Operating characteristics of 18 different continuous-flow jet nebulizers with beclomethasone dipropionate liposome aerosol.

A study of 18 different commercially available continuous-flow, jet nebulizers was performed with a standard liposomal formulation of beclomethasone dipropionate (Bec-DP) prepared with dilauroyl phosphatidylcholine (Bec-DLPC). The analysis compared the total Bec-DP output from aqueous suspensions of Bec-DLPC containing an initial starting reservoir concentration of 0.5 mg/ml. Aerosols from each nebulizer tested were characterized by the mass median aerodynamic diameter, geometric standard deviation, drug output, and the predicted percentage regional deposition of inhaled Bec-DLPC liposomes within the human respiratory tract. These data can provide a basis for the selection of commercially available jet nebulizers for use with glucocorticoid liposome aerosols for treatment of asthma and other inflammatory lung diseases.

Aerosols↗

PubMed1990

Auxiliary production of antibodies to ocular antigens in experimental autoimmune uveoretinitis.

In experimental autoimmune uveoretinitis (EAU), there are concurrent autoreactive humoral and cellular immune responses. Many studies have recently focused on T-cell reactivities in EAU, while analysis of autoantibody responses to uveitogenic epitopes has been less well characterized. In this study, a defined 16-mer uveitogenic interphotoreceptor retinoid binding protein (IRBP) peptide, designated #896, was used to induce EAU. Histological analysis of eyes at day 10 demonstrated extensive leukocyte infiltration of the anterior segment, with mononuclear and plasma cells in the posterior segment. The presence of plasma cells suggests local production of antibodies within the eye. ELISA analyses of serum, aqueous, and vitreous from rats with IRBP-induced, severe EAU revealed the presence of antibodies against peptide #896. There was little difference between the serum and intraocular antibody titers, presumably due to breakdown of the blood-ocular barriers. In addition to the anti-#896-IRBP antibodies, there were detectable antibodies reactive against separate and distinct IRBP epitopes, as well as, against epitopes on retinal-S antigen. These results indicate that in #896-peptide-induced severe EAU, humoral immune responses are induced to the primary immunogen and that there is also auxiliary production of autoreactive antibodies against other epitopes present on intraocular antigens. These auxiliary responses may contribute to the immunopathogenesis of severe EAU.

Amino Acid Sequence↗

PubMed1989

HPLC chromatofocusing of human immunoglobulins.

A method is described for fractionation and analysis of IgA, IgM, and IgG and antibodies in human serum and/or plasma using a combination of HPLC chromatofocusing and immunoassay. A pH 9.0-3.2 gradient is utilized to separate the major proteins in the complex biological samples and monoclonal antibody based ELISAs used to determine the isotype profiles. Antigen-specific ELISAs are subsequently utilized to determine the distribution of antibody species within the chromatofocused specimens. This method is versatile since multiple simultaneous assays can easily be run on each fraction generating extensive qualitative information regarding immunoglobulin classes, subclasses, and antibodies and their distribution profiles. Such spectra will prove useful for experimental kinetic analysis of the humoral immune status of humans and experimental animals.

Antibodies, Viral↗

PubMed1989

In vitro phenotypic and functional characterization of human pigment epithelial cell lines.

We have characterized human retinal pigment epithelium (HRPE) for the expression of cell surface antigens. Primary HRPE cultures, established cell lines, and freshly brushed pigment epithelial cells all express HLA-ABC but not HLA-DR antigens. However, both primary cultures and established cell lines can be induced by gamma interferon stimulation to express HLA-DR in a dose dependent manner. Only freshly brushed HRPE cells express Fc, and no cells demonstrated the presence of C3b. Our results show that HRPE cells change in culture, as reflected by the loss of Fc receptors, but retain the ability to synthesize HLA-ABC spontaneously and HLA-DR upon stimulation.

Adolescent↗

PubMed1988

Induction of keratouveitis by capsaicin.

The nervous system has profound modulatory influences on many inflammatory processes, particularly within the eye. These properties are in part mediated via neuropeptides. The neurotoxin, capsaicin, has been utilized as a valuable experimental tool to study the role of neuropeptides in many organ systems. Retrobulbar injection of capsaicin into rats results in the loss of sensory nerve function with rapid onset of inflammation (6-12 hours) which is confined to the the anterior segment. The hallmark of the acute response at 24-48 hours is marked polymorphonuclear leukocyte (PMN)/mononuclear cell influx and opacification of the corneal stroma with degeneration and loss of the central epithelium. PMN/mononuclear cell infiltration was also evident within the angle, the anterior chamber, and the iris. The corresponding posterior segments were normal. There was extensive corneal neovascularization between 7 and 14 days. This keratouveitogenic response in rats was age-dependent and can be attenuated by prior systemic pretreatments with capsaicin. This model should prove to be useful in the study of mechanisms of intraocular neurogenic inflammation.

Age Factors↗

PubMed1988

Analysis of human corneal IgG by isoelectric focusing.

Parameters which regulate the localization and retention of IgG within the corneal stroma are complex and poorly understood. Although multiple factors are involved, electrostatic interactions between IgG and anionic corneal tissue components, ie, proteoglycans (PG) and glycosaminoglycans (GAG) may regulate the distribution of antibodies within the corneal stroma. Isoelectric focusing (IEF) and blotting analysis of IgG revealed a restricted pI profile for both central and peripheral regions of the normal cornea. Similar analysis of pathological corneas from keratoplasty specimens in Fuchs' dystrophy and keratoconus reveal a variable IEF profile. In the majority of keratoplasty specimens from patients with corneal edema or graft rejection, there was generally little or no IgG detectable. These results suggest that in edematous corneas where there is altered PG/GAG in the stroma and modified fluid dynamics, there is a concomitant loss of IgG. These findings may have implications for immunologic surveillance and protection of the avascular cornea.

Alkalies↗

PubMed1987

The immune response and the eye. II. The nature of T suppressor cell induction in anterior chamber-associated immune deviation (ACAID).

We studied the cellular basis for the induction of Ts cells in anterior chamber (AC)-associated immune deviation (ACAID) by using TNP-modified syngeneic spleen cells (TNP-Spl). We demonstrate that the cells responsible for the induction of TNP-ACAID are non adherent, IA- T cells. This is in contrast to the antigen-presenting cells which induce suppression after the i.v. injection of TNP-Spl which are IA+/I-J+ adherent cells. Furthermore, two T cells within the TNP-Spl population are required to initiate suppression in TNP-ACAID: one is Lyt-1+, and I-J+, the other is Lyt-1+ and reactive with a monoclonal antibody, 14-30, which specifically identifies Ts inducer cells. The antigen specificity of ACAID resides in the 14-30+ T cell, and not the I-J+ cell. Although both cells must be viable to induce suppression, neither they (nor their products) must be in direct contact within the eye; one population may be in the right AC, the other in the left. Our results suggest that it is Ts inducer cells placed into the AC of the eye which initiate TNP-ACAID, and that these cells exit (or secrete Ts factors which exit) the eye to induce Ts effector cells in the spleen.

Animals↗

PubMed1987

Uveal IgG distribution: regulation by electrostatic interactions.

The differential distribution of albumin and IgG within various intraocular tissues suggests that charge rather than serum concentration plays an important role in regulating the distribution of certain molecules within the eye. The presence of anionic sites within the uveal tract indirectly regulates the localization and binding of cationic IgG by electrostatic interactions. Our studies indicate that circulating cationic IgG antibodies of pI 9.0-10.0 readily traverse the fenestrated capillaries in the ciliary body/processes and choriocapillaris and bind within vessel walls and stromal anionic regions and Bruch's membrane. Since there is normally no IgG produced within the non-inflamed, quiescent eye, this regulatory mechanism is potentially important in mediating immunologic protection within the uvea.

Animals↗

PubMed1987

In situ immune complex formation within the uvea. Potential role of cationic antibody.

A murine model has been developed to study the role of immunoglobulin charge in the regulation of the intraocular distribution of circulating IgG antibodies. Intravenously injected cationic antibodies to the tracer enzyme horseradish peroxidase bind within the ciliary body and choroid (CB/Ch). These cationic antibodies can selectively entrap and bind circulating antigens forming immune complexes (IC) within the uveal tissues. The structure of the uvea with its fenestrated CB/Ch capillaries and fixed anionic sites (within Bruch's membrane and the stroma of the CB and processes) may predispose the CB/Ch to in situ IC formation. Local IC formation mediated initially by deposition of cationic antibodies within the uvea may play an important role in the immunopathogenesis of some forms of uveitis.

Animals↗

PubMed1986

Human sympathetic ophthalmia. Immunologic analysis of the vitreous and uvea.

The inflammatory cell reaction within the vitreous and uvea of a human eye with atypical sympathetic ophthalmia was studied immunohistologically and with the fluorescence-activated cell sorter. The uveal infiltrate consisted predominantly of T cells of the helper/inducer subset, with less than 5% of the cells characterized as B cells, plasma cells, or monocytes. These results suggest that T cells perform an important role in atypical human sympathetic ophthalmia. A similar population of mononuclear cells was observed in the vitreous inflammatory infiltrate, in marked contrast to the peripheral blood, where there was a significant depression of circulating T cells. The similarity between the inflammatory cell populations within the vitreous cavity and uvea, in contrast to the peripheral blood, underlines the importance of studying the intraocular inflammatory reaction in uveitis to gain further insight into the mechanism of this disease.

Autoimmune Diseases↗

PubMed1986

Human choroidal melanocytes in tissue culture.

Human choroidal melanocytes were isolated from eye bank tissue and cultured in vitro with 10 ng/ml cholera toxin and 10 ng/ml phorbol myristate acetate. These growth factors induced rapid proliferation of spindle-type melanocytes. Similar results were obtained using 10 mM putrescine. Phenotypic analysis of these cells by immunoperoxidase staining with anti-HLA-DR monoclonal antibodies revealed 40-70% positive cells. HLA-DR positive melanocytes were isolated and purified from the HLA-DR negative population by rosetting with protein-A coupled sheep erythrocytes followed by differential centrifugation. Ultrastructural analysis of choroidal melanocytes revealed evidence of premelanosomes and melanosomes. Choroidal melanocytes in tissue culture are important experimental controls for the study of the cell biology of choroidal melanoma.

Adolescent↗

PubMed1984

Immunologic analysis of intraocular mononuclear cell infiltrates in uveitis.

The pathogenesis of chronic idiopathic uveitis is not known. Analysis of inflammatory site (ie, intraocular) lymphocytes in the aqueous humor and/or vitreous cavity was performed with monoclonal antibodies and a cell sorter. The mononuclear cell population within the aqueous humor of eyes with acute idiopathic uveitis resembled that observed in the peripheral blood. In contrast, eyes with chronic idiopathic uveitis displayed a scarcity of T cells within the vitreous. Eyes with chronic uveitis of presumed infectious cause did not show similar changes. These observations are consistent with the hypothesis that intraocular T-cell immunoregulation of B-cell function may be defective in some stages of chronic idiopathic uveitis.

Aqueous Humor↗

PubMed1984

Immunologic insights into uveitis and retinitis: the immunoregulatory circuit.

The immune response is a complex series of cellular interactions, which is controlled by several regulatory mechanisms to insure an appropriate response. One of the most important mechanisms of control is the suppressor T cell immunoregulatory circuit. The immune response is presented in detail and examined from three different perspectives: 1) a clinical disease in which it is markedly abnormal--namely, the acquired immune deficiency syndrome or AIDS, 2) a clinical disease in which no systemic abnormality is apparent but where a local derangement in immunoregulation may be important--namely, idiopathic uveitis, and 3) a situation in which it is purposefully altered by medications for therapeutic purposes. Three drugs currently used in the treatment of uveitis--prednisone, cyclophosphamide, and cyclosporine--will be examined and compared.

Acquired Immunodeficiency Syndrome↗