Total BSA Research Articles

Changing the Way We Think About Burn Size Estimation.

Burn size estimation is a crucial component of acute burn management that guides referral to burn centers, fluid resuscitation parameters, hospital resource distribution, and mortality-based interventions. Referring providers often misestimate the total BSA (TBSA) of burn injury, which contributes to unnecessary healthcare costs, misappropriation of limited resources, and delay in provision of appropriate patient care. A systematic literature review of articles available on PubMed, Scopus, Google Scholar, OvidSP Medline, and Web of Science was performed. All articles were evaluated in a standardized fashion by a panel of reviewers to assess applicability to the research question. Twenty-six relevant articles identified pervasive TBSA miscalculations ranging from 5% to 339% regardless of provider level with < 20% TBSA burns being disproportionately overestimated. This resulted in up to 77% of burns being inappropriately transferred to burn centers from referring hospitals. Improper use of TBSA estimation tools (palm, hand, Rule of 9s) without considering patient body mass index, race, age, and sex standards contributes to TBSA misestimation. Few studies with limited sample sizes argue that TBSA misestimations significantly affect fluid resuscitation volume, although the findings suggest that small burns (<20% TBSA) are over-estimated and over-resuscitated-the opposite of larger burns. TBSA misestimation is associated with an increased incidence of inappropriate transfers to burn centers and the associated costs. The data remains lacking, however, and larger studies are required to further elucidate the clinical impact of such errors. A systematic approach with telemedicine-facilitated computer-based burn assessments is required.

Social Interactions and Social Activities After Burn Injury: A Life Impact Burn Recovery Evaluation (LIBRE) Study.

Social interactions and activities are key components of social recovery following burn injuries. The objective of this study is to determine the predictors of these areas of social recovery. This study provides a secondary analysis of a cross-sectional survey of adult burn survivors. The Life Impact Burn Recovery Evaluation-192 was administered to 601 burn survivors for the field-testing of the Life Impact Burn Recovery Evaluation Profile. Survivors aged 18 years and older with injuries ≥5% total BSA or burns to critical areas (hands, feet, face, or genitals) were eligible to participate. Multivariate linear regression analyses were used to determine predictors of the Social Activities and Social Interactions scale scores. A total of 599 people completed the Social Interactions and Social Activities scales. Of these, 77% identified as White Non-Hispanic, 55% were female, 55% were unmarried, and 80% had burns to critical areas. Participants had a mean age of 45 years, a mean time since burn injury of 15 years, and a mean burn size of 41% total BSA. Younger age (P < .01) and being married/living with a significant other (P ≤ .01) were associated with higher Social Activities and Social Interactions scale scores. Individual item responses reveal that survivors had lower scores on items related to participating in outdoor activities (30.4%) or feeling uncomfortable with their appearance (32.4% report dressing to avoid stares). Social interactions and activities are long-term challenges for burn survivors. It is important for clinicians to identify patients who may struggle with social recovery in order to focus on future community-based interventions.

Nanoparticle formulation having ability to control the release of protein for drug delivery application

Controlled release of therapeutic protein is desirable for protein delivery applications. This study discuss about a unique nanomaterial which is capable to provide the protein release in controlled manner. The nanomaterial has been synthesized from folic acid molecules and bovine serum albumin (BSA11BSA: Bovine serum albumin) is loaded in these nanoparticles as a model protein. The size distribution of the synthesized folic acid nanoparticles was observed between 200 and 300nm. The release study using high performance liquid chromatography suggests that more than 90% of BSA can be encapsulated in the nanoparticles having BSA loaded up to 19.29mg (57% of folic acid loaded). Release study also reveals that more than 95% of the total folic acid and BSA were released in phosphate buffer saline solution within 48h. Investigation of folic acid release along with BSA release reveals that the particles are formed through folic acid-protein complex. Salt concentration in the release medium and crosslinked cations in the nanoparticles are found to be the key parameters to control the release rate. Thus, folic acid nanoparticles are efficient carrier for protein encapsulation and release in the controlled manner with minimum drug loss.

Use of Air Transport for Minor Burns: Is There Room for Improvement?

Since 1981, the number of US burn centers has decreased by 29%, resulting in more long distance referrals to remaining facilities. Air transport is often the only feasible method for remote patients to reach few remaining burn centers. A significant proportion of flown-in patients have minor burns and are discharged within 24 hours, representing potential over-utilization of resources with increased cost to the healthcare system for no perceptible benefit. We explored factors associated with air transport of burns and opportunities for system improvement. Retrospective review of burn patients transferred by air to regional burn center between January 2003 and June 2013. Demographic, injury and clinical outcome data were acquired from the institutional Burn Registry. Minor burns constituted 17.7% of all flown admits (236/1331). Children were more likely to be included in this cohort at 32% vs 21.6% of adults (P = .0004). The overtriaged cohort had significantly lower % total BSA than accurately triaged cohort (3.3% vs 15%; P = .0001). Subjects with electrical burn injury were twice as likely to be overtriaged than accurately triaged (10.6% vs 5%; P = .002). The average % total BSA in the overtriaged group was 3.3%; the face was most common area burned (47.7%). The average estimate of charges for transfer was between $25,000 and 30,000/patient. The incidence of overtriage among flown-in burn patients, approximately 20%, represents substantial unnecessary healthcare expenditure. Improved burn care education, incentives to increase use of telemedicine, and modification of American Burn Association guidelines to include consultation with a burn center rather than automatic transfer are needed to reduce this cost to the healthcare system.

Lower Serum Albumin Shortly After Admission Predicts Prolonged Hospital Stay in Younger Burn Patients.

The purpose of this study was to assess whether albumin levels could be used to aid in the prediction of hospital stay in adult burn patients. A retrospective review of burn patients from 2009 to 2014 was used. Demographic, injury details, albumin levels within 72 hours of admission, and clinical outcomes were recorded. The abbreviated burn severity index (ABSI) was calculated for each patient. Hospital stay >3 weeks was defined as "prolonged stay." Since albumin showed a significant interaction with age, patients were divided into two groups based on a median age of 40 years. Albumin, total BSA, and ABSI were each used as predictors, and the area under the curve (AUC) of a receiver operating characteristic curve was calculated. A composite score was created for the ≤ 40 years age group using ABSI and albumin levels to predict an increased length of stay. Thirty-eight of 198 (19.2%) patients had a stay >3 weeks. The AUCs for albumin level, total BSA, and ABSI alone in younger patients were 0.97, 0.97, and 0.96, respectively. Among patients older than 40, the AUC values were substantially lower indicating lower predictive value. The probability of prolonged stay for patients with albumin level ≥ 2.4 g/dl was low (.8%) compared with those with albumin level <2.4 g/dl (96.5%). Adding ABSI to this model increased predictive accuracy. Albumin level obtained within 72 hours of admission was an effective predictor of prolonged hospital stay in adult burn patients ≤ 40 years.

Long-Term Skeletal Muscle Mitochondrial Dysfunction is Associated with Hypermetabolism in Severely Burned Children

The long-term impact of burn trauma on skeletal muscle bioenergetics remains unknown. Here, the authors determined respiratory capacity and function of skeletal muscle mitochondria in healthy individuals and in burn victims for up to 2 years postinjury. Biopsies were collected from the m. vastus lateralis of 16 healthy men (26 ± 4 years) and 69 children (8 ± 5 years) with burns encompassing ≥30% of their total BSA. Seventy-nine biopsies were collected from cohorts of burn victims at 2 weeks (n = 18), 6 months (n = 18), 12 months (n = 25), and 24 months (n = 18) postburn. Hypermetabolism was determined by the difference in predicted and measured metabolic rate. Mitochondrial respiration was determined in saponin-permeabilized myofiber bundles. Outcomes were modeled by analysis of variance, with differences in groups assessed by Tukey-adjusted contrasts. Burn patients were hypermetabolic for up to 2 years postinjury. Coupled mitochondrial respiration was lower at 2 weeks (17 [8] pmol/sec/mg; P < .001), 6 months (41 [30] pmol/sec/mg; P = .03), and 12 months (35 [14] pmol/sec/mg; P < .001) postburn compared with healthy controls (58 [13] pmol/sec/mg). Coupled respiration was greater at 6, 12, and 24 months postburn vs 2 weeks postburn (P < .001). Mitochondrial adenosine diphosphate and oligomycin sensitivity (measures of coupling control) were lower at all time-points postburn vs control (P < .05), but greater at 6, 12, and 24 months postburn vs 2 weeks postburn (P < .05). Muscle mitochondrial respiratory capacity remains significantly lower in burn victims for 1-year postinjury. Mitochondrial coupling control is diminished for up to 2 years postinjury in burn victims, resulting in greater mitochondrial thermogenesis. These quantitative and qualitative derangements in skeletal muscle bioenergetics likely contribute to the long-term pathophysiological stress response to burn trauma.

Outcomes in Adult Survivors of Childhood Burn Injuries as Compared with Matched Controls.

Limited research exists examining long-term mental and physical health outcomes in adult survivors of pediatric burns. The authors examine the postinjury lifetime prevalence of common mental and physical disorders in a large pediatric burn cohort and compare the results with matched controls. Seven hundred and forty five survivors of childhood burns identified in the Burn Registry (<18 years old and total BSA >1% between April 1, 1988 and March 31, 2010) were matched 1:5 to the general population based on age at time of injury (index date), sex, and geographic residence. Postinjury rate ratio (RR) was used to compare burn cases and control cohorts for common mental and physical illnesses through physician billings, and hospital claims. RR was adjusted for sex, rural residence, and income. Compared with matched controls, postburn cases had significantly higher RR of all mental disorders, which remained significant (P < .05) after adjustment (major depression RR = 1.5 [confidence limit {CL}: 1.2-1.8], anxiety disorder RR = 1.5 [CL: 1.3-1.8), substance abuse RR = 2.3 [CL: 1.7-3.2], suicide attempt RR = 4.3 [CL: 1.6-12.1], or any mental disorder RR = 1.5 [CL: 1.3-1.8]). The relative rate of some physical illnesses was also significantly increased in burn survivors: arthritis RR = 1.2 (CL: 1.1-1.4), fractures RR = 1.4 (CL: 1.2-1.6), total respiratory morbidity RR = 1.1 (CL: 1.02-1.3), and any physical illness RR = 1.2 (CL: 1.1-1.3). Adult survivors of childhood burn injury have significantly increased rates of postburn mental and physical illnesses. Screening and appropriate management of these illnesses is essential when caring for this population.

Proteasome Inhibition After Burn Injury.

The objective of this study was to assess the effects of proteasome inhibition on the development of burn-induced hypermetabolism. Rats underwent 30-40% total BSA scald burn or sham injury. The proteasome inhibitor bortezomib (0.1 mg/kg) or vehicle (n = 10) was administered i.p. 3× weekly starting at 2 hours (early bortezomib, n = 20) or 48 hours (late-bortezomib, n = 13) postburn. Body weights were determined weekly. Resting energy expenditures (REE) were measured at days 0 (baseline), 7, 14, 21, and 42 postburn. At day 42, blood and pectoral muscle were harvested. Routine blood chemistry parameters were analyzed. Proteasome content, proteasome peptidase activities, and ubiquitin-protein conjugates were measured in muscle extracts. As compared with sham-vehicle-treated animals, specific proteasome activities were increased after burn and vehicle treatment. Bortezomib treatment inhibited proteasome activities and increased ubiquitin-protein conjugates after sham and burn injury. Bortezomib treatment did not affect REE after sham procedure. REE significantly increased by 47% within 7 days and remained elevated until day 42 after burn and vehicle treatment. After early-bortezomib treatment, burn-induced increases in REE were delayed and significantly reduced by 42% at day 42, as compared with vehicle treatment. With late-bortezomib treatment, burn-induced increases in REE were also delayed but not attenuated at day 42. Mortality was 20% with vehicle, 65% (median survival time: 1.875 days) with early-bortezomib and 25% with late-bortezomib treatment after burns (P < .05 early-bortezomib vs vehicle and late-bortezomib). Proteasome inhibition delays development of burn-induced hypermetabolism. Although proteasome inhibition early after burn injury reduces the hypermetabolic response, it significantly increases early burn-associated mortality.

Morphological Changes in Subcutaneous White Adipose Tissue After Severe Burn Injury.

Severe burn injury produces a plethora of metabolic abnormalities which contribute to the prolonged morbidity of burn survivors. The authors have recently demonstrated trans-differentiation of white adipose tissue (WAT) after burn trauma, toward a more thermogenic phenotype. However, the impact of burn injury on subcutaneous WAT (sWAT) morphology in humans is unknown. Here, the authors studied the effect of severe burn injury on the architecture of sWAT. sWAT was collected from 11 severely burned children (11 ± 3 years; 55 ± 16% total BSA burned) and 12 nonburned healthy children (9 ± 3 years). Histology, electron microscopy, immunohistochemistry, and immunofluorescence were performed on fixed adipose tissue sections. sWAT cytokine and collagen concentrations were measured by multiplex assay and sirius/fast green staining method, respectively. sWAT histology demonstrated multiple fat droplets, significantly (P < .05) reduced mean cell size (104 ± 6 vs 68 ± 3 μm) and higher collagen content (7 ± 0.8 vs 4 ± 0.4) in burn patients. sWAT from burn victims stained positive for CD68 suggesting infiltration of macrophages. Furthermore, electron microscopic analysis showed multiple fat droplets and greater mitochondrial abundance in sWAT of burn survivors. In agreement with this, mitochondrial respiratory capacity in the leak and coupled state increased by 100% in sWAT of burned children from 1 to 3 weeks postinjury. The cytokines IL-6, IL-8, IL-13, IL-1a, IL-1b, MCP-1, and TNF-α were all significantly greater in the sWAT of burned children versus healthy children (P < .05). Furthermore, IL-6, IL-8, IL1-a, IL-1b, and TNF-α significantly increased after injury in sWAT of burned children (P < .05). This study provides detailed evidence of morphological and functional changes in sWAT of burn survivors which was associated with tissue inflammation. A better understanding of morphological and functional changes in sWAT will help discern the mechanisms underlying hypermetabolism in burned patients.

Effects of Estrogen on Bacterial Clearance and Neutrophil Response After Combined Burn Injury and Wound Infection.

Females have a higher rate of mortality following burn injury, largely due to differences in sepsis-related mortality. The present study seeks to understand the underpinnings of the estrogen's immunomodulatory effects in a murine model of burn injury and infection. Gonad-intact and ovariectomized female mice were subjected to a 15% total BSA scald injury and then inoculated with 3000 CFU of Pseudomonas aeruginosa by topical application to the wound. Animals were killed at 1, 2, or 7 days after injury. Tissue and whole blood were collected. Cultures were performed of all tissues to assess for bacteria content. Lungs were examined for histologic appearance and homogenates were analyzed for chemokines and myeloperoxidase activity. Mortality reached 95% by 3 days after injury for gonad intact mice, whereas in ovariectomized mice it was 76% at 7 days. Blood and tissue samples from gonad intact mice had significantly higher levels of P. aeruginosa compared with ovariectomized mice. Histologic assessment of lungs demonstrated a similar overall cellularity in ovariectomized mice relative to gonad intact mice 1 day after injury, but increased neutrophil count in gonad intact mice. This correlated with chemotactic signaling as lung homogenates had lower levels of KC in ovariectomized mice (128.0 ± 19.8 vs 48.3 ± 5.7 pg/mg protein). Also, myeloperoxidase was significantly lower in lung homogenates of ovariectomized mice (1.12 ± 0.34 vs 0.56 ± 0.08 units/mg protein). Ovariectomy confers an early, but brief survival advantage in female mice after burn injury and wound infection. This appears to be secondary to enhanced bacterial clearance.

Form influences function: Anthropometry and orthostatic stability during sustained acceleration in a short arm human centrifuge

IntroductionThe goal of this study was to determine which anthropometric factors measured via air displacement plethysmography (ADP) play a significant role in augmenting orthostatic stability during sustained acceleration G-force (+G) exposure in a short arm human centrifuge (SAHC). The authors hypothesized that test subjects with a greater normalized fat free mass in percentage of total body mass (FFM%) would exhibit greater orthostatic stability during consecutive +G loads. MethodsTwenty +G naive test subjects (10 female, 10 male), were recruited for this study, in which they underwent 2 rounds of 1/2/1G-force profile in a SAHC. Before being exposed to +G, each subject underwent anthropometric analysis via ADP to ascertain total body mass (BM, kg), body volume (BV, L), body surface area (BSA, m2), normalized fat mass/fat free mass in percentage of total body mass (FM% and FFM%). During SAHC exposure, hemodynamic parameters were continuously obtained from each test subject. The measured anthropometric parameters were compared against baseline mean arterial pressure (MAP, mmHg), heart rate (HR, bpm), stroke volume (SV, mL) cardiac output (CO, Lmin−1) and systemic vascular resistance (SVR, dynscm−5) to determine correlations. ResultsFrom the 20 subjects, 13 test subjects (5 F, 8 M) completed all phases of +G exposure, and were therefore classified as having high +G tolerance (NALOC). From the 7 remaining test subjects (5 F, 2 M); 6 aborted or reduced their +G exposure, and were therefore classified as exhibiting low +G tolerance (ALOC). One subject dropped out prior to testing, and is not included in the data. Total BM, BV, and BSA were significantly higher (p<0.05) in the NALOC group. Significant correlations between baseline SV/CO and these parameters were also determined. FFM% showed no differences between the two groups, and did not exhibit any correlations with baseline hemodynamics. NALOC subjects tended to have a higher CO and SV at baseline, whereas ALOC subjects tended to exhibit higher SVR at baseline. DiscussionTotal BM, BV, and BSA were the anthropometric factors associated with orthostatic stability during +G. The higher these parameters, the higher the baseline SV, which combined contributed to greater orthostatic stability during +G. Male test subjects had an overall advantage over females via increased body dimensions and augmented cardiac function. Anthropometric analysis via ADP thus reveals critical information regarding how anthropometry influences hemodynamic function and further studies on this topic are warranted.

ORGAN DYSFUNCTION AS ESTIMATED BY THE SEQUENTIAL ORGAN FAILURE ASSESSMENT SCORE IS RELATED TO OUTCOME IN CRITICALLY ILL BURN PATIENTS

The objectives of the study were to assess organ dysfunction in burn patients by using the Sequential Organ Failure Assessment (SOFA) score, to determine the relationship between early (day 1) and late (day 4) organ dysfunction, as well as the change in organ dysfunction from admission to day 4, and mortality. The design was a prospective observational cohort study. Patients were admitted to our intensive care burn unit with severe thermal burns (> or =20% total body surface area [BSA] burned) or inhalation injury with a delay from injury to admission less than 12 h and a length of stay less than 3 days (n = 439; age, 46.0 +/- 20.3 yrs; total BSA burned, 31.6% +/- 20.2% [mean +/- SD]; inhalation injury, 44.4%; crude mortality, 18.5%). Sequential Organ Failure Assessment scores were measured on admission (SOFA 0) and on subsequent days (SOFA 1, SOFA 2, SOFA 3, and SOFA 4). The difference between SOFA 0 and SOFA 4 (DeltaSOFA 0-4) was calculated. Multivariate logistic regression analyses, including other variables associated with mortality in the models, were performed to calculate adjusted odds ratios (ORs) of organ dysfunction measurements for mortality. After adjusting for age, BSA burned, diagnosis of inhalation injury, and sex, SOFA 1 (OR, 1.89; 95% confidence interval [CI], 1.55-2.32), SOFA 4 (OR, 1.33; 95% CI, 1.19-1.47), and DeltaSOFA 0-4 (OR, 1.40; 95% CI, 1.28-1.55) were independently associated with mortality. The SOFA score is useful to assess organ dysfunction in burn patients. Burn-induced organ dysfunction (early and late), as well as the change in organ dysfunction, is independently associated with mortality.

A novel method for the preparation of biodegradable microspheres for protein drug delivery

Microspheres are potential candidates for the protein drug delivery. In this work, we prepared polymer-coated starch/bovine serum albumin (BSA) microspheres using co-axial electrohydrodynamic atomization (CEHDA). First, starch solution in dimethyl sulphoxide (DMSO) was prepared and then an aqueous solution of BSA was added to it to make a starch-BSA solution. Subsequently, this solution was made to flow through the inner capillary, while the polymer, polydimethylsiloxane (PDMS), flowed through the outer capillary. On collection, filtration and subsequent drying, near-monodisperse microspheres of 5-6microm in size were obtained. The microspheres were characterized by Fourier-transform infrared (FT-IR) spectroscopy and scanning electron microscopy. Cumulative BSA release was investigated by UV spectroscopy. BSA structure and activity was preserved in the microspheres and its release in 0.01M phosphate buffered saline (PBS) was studied over a period of 8 days. There was an initial burst with 32wt% of total BSA released in 2h. Overall 75wt% of BSA was released over a 7 day period.

CARDIAC CATHETERIZATION AS A NOVEL CAUSE OF FATAL TOXIC EPIDERMAL NECROLYSIS (TEN) INVOLVING A SIGNIFICANT PORTION OF THE GASTROINTESTINAL TRACT

Our case represents a previously unreported, fatal complication of cardiac catheterization. We report a fatal case of toxic epidermal necrolysis (TEN) involving a majority of the body surface of this patient as well as a significant portion of his upper gastrointestinal tract. TEN was induced by the nonionic radiocontrast agent used in the cath. Mr. W was a 62-year-old male, who underwent outpatient cardiac catheterization for unstable angina. He had a history of DMII, hyperlipidemia, and renal insufficiency. The cath revealed three-vessel CAD. Two days after returning home, the patient became edematous and blistering of his skin developed. This exanthem eventually resolved. Conservative medical management was pursued, but the patient continued to have symptoms. Four months later, he was admitted for a second cardiac catherterization. He was pretreated with prednisone, diphenhydramine, and ranitidine. Intravenous fluids and N-acetylcysteine were also administered. Findings once again revealed three-vessel disease. Several hours later, the nursing staff noted a generalized red rash, and a fever to 102 F. Within two days, his skin began to slough off near the neck and upper torso. The desquamation spread, reaching his buccal mucosa. The dermatology service took skin biopsies, which were consistent with toxic epidermal necrolysis. He was transferred to the regional burn center. There, he was diagnosed with 70% total BSA involvement. He became hypotensive, bacteremic and required vasopressor support and sustained a myocardial infarction and respiratory failure. The patient began having hematemesis and passing hematochezia, and a 6-gram drop in hemoglobin was noted. Upper endoscopy revealed diffuse gastritis. A PPI infusion was begun. Several days later, his nasogastric tube which yielded large amounts of bright red blood, prompting repeat EGD. This time, sloughing of his esophageal and gastric mucosa was noted, consistent with GI involvement of TEN. Compared with his prior EGD, there was a marked progression of a diffuse, confluent gastritis and duodenitis with ulceration. The mucosa sloughed readily upon any contact with instrument or lavage. The entire upper GI tract from upper esophagus through duodenum was involved and bleeding. Renal failure developed requiring dialysis. Upon request of the family, care was withdrawn. The patient expired twenty-one days after his second cardiac catheterization.

Fabrication of microspheres using blends of poly(ethylene adipate) and poly(ethylene adipate) / poly(hydroxybutyrate-hydroxyvalerate) with poly(caprolactone): Incorporation and release of bovine serum albumin

Spherical microspheres composed of polymer blends 80: 20 PEAD/PCL II and 40:40: 20 PEAD/P(HB-HV)/PCL II containing a range of BSA loadings have been fabricated using a single emulsion technique with solvent evaporation. 80: 20 PEAD/PCL II microspheres had smooth surfaces while 40:40:20 PEAD/P(HB-HV)/PCL II microspheres consisted of a mixture of smooth surfaced, microporous and macroporous microsphere fractions. Irrespective of fabrication polymer, microspheres were produced in high yield (> 75%) and BSA incorporation had no significant effect on microsphere size distribution which ranged from 0.6 to 5 μm and from 2.1 to 50 μm for 80: 20 PEAD/PCL II and 40:40: 20 PEAD/P(HB-HV)/PCL II microspheres, respectively. The loss of BSA by partitioning into the aqueous phase resulted in low encapsulation efficiencies (< 14.5%). BSA release increased significantly with theoretical percentage loading but the relationship could not be confirmed when the total cumulative release of BSA was expressed as a percentage of the actual total BSA incorporated. Significant BSA release could be detected for up to 26 days.

The role of nitric oxide in the regulation of macromolecular transport in rat jejunum.

1. Nitric oxide is known to affect epithelial and microvascular permeability and is a major non-adrenergic non-cholinergic neurotransmitter in the intestine. We have previously demonstrated neuronal regulation of macromolecular transport in the intestine. To define this regulation further the role of nitric oxide was investigated. 2. Stripped rat jejunum was mounted in Ussing chambers exposing the mucosal surface to bovine serum albumin (BSA; 2 mg ml-1), or BSA (2 mg ml-1) plus [125I]BSA (10 microCi). Following a 50 min equilibration, serosal fluids were sampled for four 10 min periods, and fluxes determined for intact BSA by enzyme-linked immunosorbent assay (ELISA) and total BSA by [125I]BSA under basal conditions, and after treatment with NG-nitro-L-arginine-methyl ester (L-NAME) alone or in conjunction with L-arginine or decarboxylated molsidomine (SIN 1). 3. L-NAME significantly increased intact BSA uptake. Total (intact + degraded) BSA flux was not altered. The L-NAME effect was reversed by L-arginine and SIN 1. Additional experiments were performed by adding the nitric oxide donors sodium nitroprusside and SIN 1 directly to control tissue. Nitric oxide donors did not further decrease intact BSA flux below levels obtained from control tissue. The L-NAME enantiomer D-NAME had no effect. Sodium-free bathing solutions also had no effect on intact BSA uptake. Non-specific permeability, as assessed by the serosal to mucosal movement of [51Cr]ethylene-diamine-tetraacetate ([51Cr]EDTA), was decreased with L-NAME. 4. The findings indicate that nitric oxide downregulates intact macromolecular flux in the small intestine.

The incorporation and release of bovine serum albumin from poly(β-hydroxybutyratehydroxyvalerate) microspheres

Spherical microporous matrix type microspheres composed of 330 kD P(HB-HV) (10.8% HV) 20%PCL II containing a range of %BSA loadings have been fabricated using a single emulsion technique with solvent evaporation. Microspheres were generated in high yield (> 75%) and the percentage incorporation of BSA had no significant effect on microsphere size distribution, typically 6-50 microns in diameter with a mean of 26.28 +/- 2.34 microns, n = 25, for 20% BSA loaded microspheres. The loss of BSA both by partitioning into the aqueous continuous phase and through micropores generated during the precipitation of the fabrication polymer concomitant with solvent evaporation resulted in a low encapsulation efficiency (< 15%). When the total cumulative release of BSA was expressed as a percentage of the actual total BSA incorporated, BSA release was only marginally influenced by the theoretical percentage loading suggesting that the amount and duration of BSA release in vitro was initially influenced as much by micropore number and diameter as by the extent of matrix BSA loading and detectable levels of BSA release could be monitored for up to 24 days.