Continuous paravertebral extrapleural infusion for post-thoracotomy pain management.

BACKGROUND: Continuous thoracic epidural analgesia is considered by many the gold standard for post-thoracotomy pain control but is associated with its own complications. In this study we compare continuous paravertebral extrapleural to epidural infusion for post-thoracotomy pain control. METHODS: In a prospective fashion, 50 patients were randomized to receive either paravertebral or epidural infusion for post-thoracotomy pain control. The anesthesia department placed epidurals, and the operative surgeon placed unilateral paravertebral catheters. Patients were evaluated for analgesic efficacy and postoperative complications. RESULTS: We found that both methods of analgesia provide adequate postoperative pain control. Epidural infusion demonstrated an improved efficacy early in the postoperative course but provided statistically similar analgesia to paravertebral by postoperative day 2. Neither group demonstrated a greater number of pain-related complications. Narcotic-induced complications such as pruritus, nausea/vomiting, and postural hypotension/mental status changes/respiratory depression were seen with statistically similar frequency in both epidural and paravertebral arms. Urinary retention, however, was noted to be significantly more frequent in patients with epidural catheters. Drug toxicity was not observed with either epidural or paravertebral infusion. CONCLUSIONS: We recommend continuous paravertebral infusion as an improved method of post-thoracotomy analgesia that can be placed and managed by the surgeon.

Controlled release microparticles as a single dose diphtheria toxoid vaccine: immunogenicity in small animal models.

Diphtheria toxoid (DT) was encapsulated in microparticles prepared from polylactide-co-glycolide (PLG) polymers using a solvent evaporation technique. Combinations of small and large sized microparticles with controlled release characteristics were used to immunize Sprague Dawley rats and the antibody responses were monitored for one year. For comparison, control groups of rats were immunized at 0, 1 and 2 months with DT adsorbed to alum. The antibody responses generated by the microparticles were comparable to the alum immunized control groups from 32 weeks. Microparticles with a single entrapped antigen (DT) induced better antibody responses than microparticles with two antigens entrapped simultaneously (DT + TT). Microparticles prepared from a single polymer were less effective for long term antibody induction than a combination of microparticles prepared from three different polymers. A combination vaccine consisting of antigen absorbed to alum and also entrapped in microparticles gave the best response. In an inhibition assay designed to determine the relative binding of antisera to the antigen, the sera from the microparticle and the alum immunized animals showed comparable binding. An intradermal challenge study was performed in rabbits, which showed similar levels for the alum and the microparticle immunized animals at 4, 12 and 32 weeks after immunization.

Biodegradable microparticles with an entrapped branched octameric peptide as a controlled-release HIV-1 vaccine.

Polyactide-co-glycolide microparticles, with an entrapped branched octameric peptide from human immunodeficiency virus (HIV-1), were prepared by a solvent evaporation method. The microparticles were characterized for size distribution, antigen loading level, and integrity. Mice in one group were each immunized with a single dose of a controlled-release microparticle formulation containing 300 micrograms of peptide and the serum IgG responses to the antigen were compared with those of mice from a second group that were immunized at 0, 4, and 26 weeks with 100-microgram doses of the same peptide immunogen adsorbed to alum. The controlled-release microparticles induced an antibody response comparable to that from the alum-immunized group. The subcutaneous and the intramuscular routes of administration were compared in additional groups of mice for the microparticles, and both routes induced similar responses. A suspending vehicle for the microparticles was also evaluated and did not affect the immunogenicity of the controlled-release formulation containing both small and large microparticles, although the immunogenicity of smaller microparticles immunized alone was affected.

Immunogenicity and protection in small-animal models with controlled-release tetanus toxoid microparticles as a single-dose vaccine.

Tetanus toxoid (TT) was encapsulated in microparticles prepared from polylactide-co-glycolide polymers by a solvent-evaporation technique. Combinations of small- and large-sized microparticles with controlled-release characteristics were used to immunize Sprague-Dawley rats, and the antibody responses were monitored for 1 year. For comparison, control groups of rats were immunized at 0, 1, and 2 months with TT adsorbed to alum. The antibody responses generated by the TT entrapped in microparticles were comparable to those generated by TT adsorbed to alum in control groups from 32 weeks onwards. Microparticles with a single entrapped antigen (TT) induced better antibody responses than microparticles with two antigens (TT and diphtheria toxoid) entrapped simultaneously. A combination vaccine consisting of TT adsorbed to alum and also entrapped in microparticles gave the best antibody responses. In an inhibition assay designed to determine the relative levels of binding of antisera to the antigens, the sera from the microparticle- and the alum-immunized animals showed comparable levels of binding. In addition, in a passive-challenge study with mice, TT adsorbed to alum and TT entrapped in microparticles provided equal levels of protection against a lethal challenge with tetanus toxin. An intradermal-challenge study was also performed with rabbits, which showed similar levels of protection in sera from alum- and microparticle-immunized animals at 4, 12, and 32 weeks after immunization.

Controlled release microparticles as a single dose hepatitis B vaccine: evaluation of immunogenicity in mice.

Hepatitis B surface antigen (HBsAg) was encapsulated in microparticles prepared from polylactide-co-glycolide (PLG) and polylactide (PLA) polymers using a solvent evaporation process. The immunoreactivity of the entrapped antigen was investigated by SDS-PAGE and Western blot. The microencapsulation process was modified to obtain both small (< 10 microns) and large microparticles (10-100 < microns). 80% of the antigen was encapsulated. Various combinations of small and large microparticles with controlled release characteristics were investigated in CD1 mice. Groups of animals were immunized with 30 micrograms equivalent of HBsAg in microparticles per animals. The control group received, three injections of 10 micrograms of HBsAg on alum at 0, 1 and 6 months. Results indicated that a single injection of HBsAg in microparticles could maintain the antibody response at a level comparable to the three-injection alum schedule for at least 1 year. An in vitro inhibition assay was developed to demonstrate that antigen-antibody reactivity were comparable for the microparticle immunized mice and the alum immunized mice. A competition assay with a monoclonal antibody specific for the neutralizing epitope of HBsAg demonstrated comparable binding for the sera from the microparticle and alum immunized mice.

The encapsulation of a model protein in poly (D, L lactide-co-glycolide) microparticles of various sizes: an evaluation of process reproducibility.

Poly (D, L lactide-co-glycolide) and poly (D, L lactide) microparticles were prepared by solvent evaporation and the process reproducibility was evaluated in terms of the loading of a model protein into the microparticles, the microparticle size and the in-vitro release profiles of the protein. The results showed that the microencapsulation method allowed the preparation of microparticles with mean sizes from < 0.5 micron to 100 microns in size, with protein entrapment from 0.5 to 5% w/w. The microparticles were smooth and free from surface defects. Moreover, the reproducibility of the preparation method was demonstrated by the in-vitro release profiles obtained using different batches of microparticles prepared under similar conditions and by the reproducibility of microparticle size and protein loading. The results demonstrated that the preparation method was both robust and reproducible and allowed the preparation of microparticles with desired characteristics in terms of loading levels, particle size and release rates.

Immunization with a soluble recombinant HIV protein entrapped in biodegradable microparticles induces HIV-specific CD8+ cytotoxic T lymphocytes and CD4+ Th1 cells.

One of the major obstacles to the development of successful recombinant vaccines against human immunodeficiency virus (HIV) and other intracellular pathogens is the identification of a safe and effective vaccine delivery system for the induction of cell mediated immunity with soluble protein antigens. In this study it was demonstrated that immunization with a recombinant HIV envelop (env) protein entrapped in biodegradable poly(lactide-co-glycolide) (PLG) microparticles induced consistent HIV-specific CD4+ and CD8+ T-cell responses in mice. Major histocompatibility complex (MHC) class I-restricted cytotoxic T lymphocytes (CTL) responses were detected following a single systemic immunization with gp120 entrapped microparticles and when given by the intranasal (i.n.) route induced HIV-specific CD8+ CTL and secretory IgA. Furthermore immunization with gp120 entrapped in microparticles generated CD4+ T cells that secreted moderate to high levels of IFN-gamma. Therefore, PLG microparticles are a safe and effective means of delivering antigen to the appropriate processing site for the generation of class I-restricted CTL, and are also capable of inducing Th1 cells.

Synthetic delivery system for tuberculosis vaccines: immunological evaluation of the M. tuberculosis 38 kDa protein entrapped in biodegradable PLG microparticles.

Tuberculosis remains a major public health burden which could be ameliorated by effective and well-defined subunit vaccines, particularly because the protective efficacy of current M. bovis BCG vaccines is both unpredictable and variable. The immunodominant 38 kDa antigen from Mycobacterium tuberculosis was entrapped in biodegradable poly (DL-lactide co-glycolide) (PLG) microparticles which served as a delivery system. Both cellular and humoral immune responses were assessed and compared with those obtained after immunization with the 38 kDa protein emulsified in incomplete Freund's adjuvant (IFA). Vaccination of mice with a single dose of antigen-loaded microparticles resulted in specific IgG titres peaking after five weeks comparable to those achieved after vaccination with protein emulsified in incomplete Freund's adjuvant (IFA). T-cell responses were found to be superior to those induced with antigen/IFA. The T- and B-cell epitope specificities ad judged with synthetic peptides were identical following immunization with antigen in microparticles or IFA. Differences in adjuvanticity were revealed by measuring antigen-specific IgG1, IgG2a and antigen-induced IFN-gamma secretion in vitro: substantially higher titres of IgG2a were observed following immunization with antigen/microparticles than with 38 kDa protein/IFA. This was paralleled by a tenfold higher secretion of IFN-gamma in mice injected with antigen/microparticles. Reduction in colony-forming units was not consistent in mice immunized with 38 kDa protein entrapped in microparticles which were subsequently infected with live tubercle bacilli. Taken together these results indicate that biodegradable PLG microparticles constitute a favorable candidate vaccine delivery system worthy of further assessment in the quest to develop better and defined agents protecting against tuberculosis.

Response of the lateral meniscus of the dog to wide incision and repair of the meniscotibial ligament.

The effects of extensive incision and reattachment of the coronary ligaments on meniscal healing in the canine were examined. Through an extensile exposure to the lateral tibial plateau, nine mongrel dogs underwent wide incision, reflection, and subsequent reattachment of their meniscotibial ligaments. At intervals of 3, 6, and 9 weeks, three dogs were killed and a gross and microscopic evaluation of their menisci and perimeniscal tissues was performed. At 3 weeks, a small region of the central meniscal periphery was found to be devoid of a vascular network. By 6 weeks, the entire peripheral vasculature had reconstituted. No specimen demonstrated histologic evidence of meniscal necrosis or degeneration. Healing occurred by fibrovascular scar.

Biodegradable microparticles for oral immunization.

Ovalbumin (OVA) was entrapped in poly(lactide-co-glycolide) microparticles and administered to mice. Following intraperitoneal immunization, the microparticles induced both proliferative T-cell responses and cytotoxic T-cell responses in spleen cells. Following oral immunization, the mean salivary IgA antibody response to microparticles was significantly greater than the response to soluble OVA (p < 0.0001). Serum IgG antibody levels were also significantly greater in the group administered microparticles (p < 0.001). Cholera toxin B subunit was also entrapped in microparticles. Following oral immunization in mice, specific antibody-secreting cells were detected both in the spleens and in the mesenteric lymph nodes.

The pharmacokinetics of trilostane and ketotrilostane in an interconverting system in the rat.

The pharmacokinetics of trilostane and one of its metabolites ketotrilostane are described and characterized in the rat following the separate intravenous administration of trilostane and ketotrilostane. It was noted during these studies that the parent compound and its metabolite undergo metabolic interconversion-trilostane producing ketotrilostane and ketotrilostane generating trilostane. This result means that trilostane is conserved in the body by interconversion--being metabolized to ketotrilostane and then subsequently back to the "parent" drug, trilostane.

Controlled release microparticles for vaccine development.

The primary and secondary sera IgG antibody responses to ovalbumin (OVA) entrapped in biodegradable poly(lactide-co-glycolide) (PLGA) microparticles were compared with the responses obtained with soluble OVA. In addition, OVA in PLGA microparticles was also administered after dispersion in an immunostimulatory vehicle, Freund's incomplete adjuvant (FIA). The primary IgG responses to OVA in microparticles/FIA were significantly greater than the responses to soluble OVA from day 14 to day 42, when booster immunizations were administered. From day 49 to the end of the study at day 84, the responses to OVA, both in microparticles alone and in microparticles/FIA, were significantly greater than the responses to soluble OVA. Nevertheless, the responses obtained for OVA in microparticles or microparticles/FIA were, in general, not as high as those obtained with OVA in Freund's complete adjuvant.

Biodegradable microparticles as controlled release antigen delivery systems.

A model but poor immunogen, ovalbumin (OVA), was entrapped in a novel antigen delivery system comprising poly (D,L-lactide-co-glycolide) (PLGA) microparticles. Both the primary and the secondary IgG antibody responses obtained with OVA in microparticles were compared to those obtained with OVA emulsified in Freunds' adjuvants by two routes of immunization, intraperitoneal (i.p.) and subcutaneous (s.c.) injection. Following single i.p. or s.c. injections, the IgG serum antibody responses to OVA in microparticles were significantly greater than the responses to OVA in Freunds' complete adjuvant (FCA) for up to 10 weeks. After s.c. booster doses of OVA, the secondary IgG antibody responses to OVA in microparticles remained greater than the secondary responses to OVA in Freunds', but not significantly so. Furthermore, the primary IgG responses to OVA in microparticles obtained 8-12 weeks after a single i.p. injection were greater than the secondary responses to OVA in Freunds' obtained by repeat s.c. injections at Weeks 0 and 6. These results demonstrate that microparticles can function as potent antigen delivery systems for an entrapped antigen. Due to their ability to degrade slowly in vivo and to release entrapped antigens, microparticles have considerable potential as controlled release antigen delivery systems for the induction of long-term immune responses.

High-performance liquid chromatographic analysis of trilostane and ketotrilostane in rat plasma.

A simple high-performance liquid chromatographic (HPLC) method for assaying trilostane, a synthetic steroid, and one of its metabolites, ketotrilostane, in small volumes of rat plasma has been developed. A single liquid-liquid extraction was used to isolate the two compounds from acidified plasma prior to the quantitative analysis. The HPLC conditions involved the use of a Spherisorb ODS column (250 mm x 4.6 mm I.D.) and a mobile phase of 1,4-dioxan-Sorenson's buffer at pH 5.0 (52:48, v/v). Ethisterone was used as an internal standard. Trilostane and ketotrilostane were detected by their ultraviolet absorbance at 255 nm. Recoveries greater than 80% and detection limits of 50 ng/ml were obtained for both compounds. Inter-day coefficients of variation were less than 10%.

Axillary thoracotomy.

The axillary thoracotomy should be the incision of choice for most uncomplicated general thoracic surgical procedures. It can be performed rapidly, avoids major muscle transection, and by employing a double lumen endotracheal tube will permit segmental resection as well as lobectomy without technical problem. One hundred consecutive, elective axillary thoracotomies were performed with minimal morbidity and only one mortality. Twenty-five of the patients were of high surgical risk. The larger posterolateral thoracotomy is reserved for repeat thoracotomy, Pancoast tumors, difficult procedures such as bronchoplasty and/or radical pneumonectomy, and when pleural symphysis is expected. Sometimes called lateral thoracotomy or mini-thoracotomy, the axillary thoracotomy is our most common incision.

The dexamethasone suppression test and clinical decision making.

Recent research has challenged the reliability and validity of the dexamethasone suppression test (DST) as a specific laboratory diagnostic tool in psychiatry. This study investigated its effects on clinical decision making. Test results were found to have minimal impact on diagnostic and treatment decisions. This finding is discussed in light of other "negative" evidence regarding the DST.