Administration Of Palmitate Research Articles

Oxidative Stress Status in Heat Shock Sheep Controlled Shearing and Ascorbyl Palmitate Administration

Indonesia has very hot temperatures and high humidity, making it unfavorable for sheep whose covered with thick fur. Shearing enlarges and accelerates heat dissipation from the sheep's body, giving antioxidants that help reduce the negative effects of excessive free radical production. Ascorbic acid is an antioxidant but is easily decomposed when it enters the digestive system of ruminants. Ascorbyl palmitate (AP) is ascorbic acid in the form of an ester which is insoluble in water. The aim of this study was to analyze the effect of shearing and administration of AP antioxidants on oxidative stress conditions in Padjadjaran sheep subjected to heat shock. The shaving treatment consisted of not shaving (s0) and shearing (s1),and the treatment of giving the antioxidant ascorbyl palmitate consisted of not being given (a0) and being given (a1). Sheep were subjected to shearing, their hair was trimmed until ± 10 mm in length was left, and sheep as object of study were treated with ascorbyl palmitate at a dose of 400 mg head-1 day-1. The combination treatment was not shaved – not given the antioxidant ascorbyl palmitate (s0a0), only shaved (s1a0), only given the antioxidant ascorbyl palmitate (s0a1), and sheared – given the antioxidant ascorbyl palmitate (s1a1). Heat shock is given by exposing the sheep to the sun. The oxidative stress observed and analyzed was the profile of endogenous antioxidants consisting of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA). The results showed that the combination of shearing and Ascorbyl Palmitate had a significant effect (p<0.05) on the levels of SOD, CAT and GSH-Px in Padjadjaran sheep receiving heat stress. The conclusion from this study, the shearing treatment and the administration of Ascorbyl palmitate, both independently and in combination, had a beneficial effect on Padjadjaran sheep.

Lysosomal Ca2+ as a mediator of palmitate-induced lipotoxicity

While the mechanism of lipotoxicity by palmitic acid (PA), an effector of metabolic stress in vitro and in vivo, has been extensively investigated, molecular details of lipotoxicity are still not fully characterized. Since recent studies reported that PA can exert lysosomal stress in addition to well-known ER and mitochondrial stress, we studied the role of lysosomal events in lipotoxicity by PA, focusing on lysosomal Ca2+. We found that PA induced accumulation of mitochondrial ROS and that mitochondrial ROS induced release of lysosomal Ca2+ due to lysosomal Ca2+ exit channel activation. Lysosomal Ca2+ release led to increased cytosolic Ca2+ which induced mitochondrial permeability transition (mPT). Chelation of cytoplasmic Ca2+ or blockade of mPT with olesoxime or decylubiquinone (DUB) suppressed lipotoxicity. Lysosomal Ca2+ release led to reduced lysosomal Ca2+ content which was replenished by ER Ca2+, the largest intracellular Ca2+ reservoir (ER → lysosome Ca2+ refilling), which in turn activated store-operated Ca2+ entry (SOCE). Inhibition of ER → lysosome Ca2+ refilling by blockade of ER Ca2+ exit channel using dantrolene or inhibition of SOCE using BTP2 inhibited lipotoxicity in vitro. Dantrolene or DUB also inhibited lipotoxic death of hepatocytes in vivo induced by administration of ethyl palmitate together with LPS. These results suggest a novel pathway of lipotoxicity characterized by mPT due to lysosomal Ca2+ release which was supplemented by ER → lysosome Ca2+ refilling and subsequent SOCE, and also suggest the potential role of modulation of ER → lysosome Ca2+ refilling by dantrolene or other blockers of ER Ca2+ exit channels in disease conditions characterized by lipotoxicity such as metabolic syndrome, diabetes, cardiomyopathy or nonalcoholic steatohepatitis.

Effectiveness of Paliperidone Palmitate in Reducing Acute Psychiatric Service Use for Patients Suffering from Psychosis-A Retrospective Mirror-Image Study.

Poor adherence to antipsychotic treatment is a leading cause of relapse for patients suffering from psychotic disorders and the use of long-acting injectable antipsychotics (LAI) may lead to improved clinical outcomes. This was a 1-year mirror-image study examining the clinical outcomes after monthly administration of paliperidone palmitate (PP1M). The primary outcome measure was the total days of psychiatric hospitalization in the 1-year before and 1-year after initiation of PP1M. Data from 158 patients were included in the study. Most of the patients suffered from schizophrenia. In the year after initiation of PP1M, the mean number of hospitalization days fell from 106.53 to 19.10 (p < 0.001). There were significant reductions in the mean number of hospitalizations and emergency room visits. The use of paliperidone palmitate is associated with significant reduction in both the number of admissions and days of psychiatric hospitalization.

Epidermal Delivery of Retinyl Palmitate Loaded Transfersomes: Penetration and Biodistribution Studies.

The alteration of retinoids levels in the skin can cause different disorders in the maturation of epithelial skin cells. Topical administration of these lipophilic molecules is a challenge that can be addressed by encapsulation into drug delivery systems. In this study, retinyl palmitate transferosomes formulated in cream were developed and the increases in the penetration of the active ingredients as well as the biodistribution were evaluated in vitro and in vivo. Transfersomes demonstrated a significant increase in the administration of retinyl palmitate to the epidermis by quantification of the active ingredients in the different layers of the skin, as well as by fluorescence microscopy of biopsies of non-dermatomized pig-ear skin. These results suggest that transfersomes may be an efficient vehicle for the delivery of retinoids to inner layers of the skin, such as the epidermis.

Administration of methyl palmitate prevents non-alcoholic steatohepatitis (NASH) by induction of PPAR-α

Background and aimsThe lack of valid therapeutic approach that can ameliorate the manifestations of NASH is a barrier to therapeutic development. Therefore, we investigate the novel role of Methyl Palmitate (MP) in preventing NASH and the possible mechanism involved. Methods50 Male C57BL/6 J mice were randomly divided into 5 groups (n = 10). The control group was fed control diet; model group was fed MCD diet; MP 1 group was fed MCD diet supplemented with MP (75 mg/kg/day); MP 2 group was fed MCD plus MP diet (150 mg/kg/day); and MP 3 group was fed MCD plus MP diet (300 mg/kg/day). Histological staining’s, and commercially available kits for serum ALT and AST and hepatic contents of TG, TC, MDA, SOD, and GSH were used to assess NASH. Furthermore, relative liver protein and gene expression levels were determined by Western Blot and qPCR, respectively. ResultsMice fed MCD diet developed NASH, which was markedly improved by MP in a dose-dependent manner. MP treatment improved hepatic content of TG, TC, MDA, SOD and GSH and serum levels of ALT and AST. In vivo studies showed that MP treatment activated PPARα expression, that in turns, promoted β-oxidation protein and gene expressions, suppressed TNFα, MCP1, TGFβ1 and Colla1 protein and gene expression levels, contributing to the prevention of NASH. ConclusionsOur results indicated that MP could successfully prevent NASH. This effect of MP was mediated through induction of PPARα pathway. This study provides a novel therapeutic target that plays pivotal role in the prevention of NASH.

Palmitate-induced lipotoxicity is crucial for the pathogenesis of nonalcoholic fatty liver disease in cooperation with gut-derived endotoxin

Although previous studies have indicated important roles of palmitate, a saturated fatty acid, in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), it remains unclear how palmitate contributes to inflammation and fibrosis in the liver. Administration of palmitate in high fat diet (HFD)-fed but not basal diet (BD)-fed mice resulted in an increase in serum alanine aminotransferase (ALT) levels. Surprisingly, combined administration of very low dose lipopolysaccharide in palmitate-treated mice led to a marked increase in serum ALT levels despite BD-fed conditions. Administration of palmitate alone in BD-fed mice caused inflammatory cell infiltration and liver fibrosis mediated by the toll-like receptor 4 pathway without ALT elevation. In addition, a significant correlation between serum free fatty acid levels and liver fibrosis stage was observed in patients with NAFLD. These results indicate that palmitate may play crucial roles in the pathogenesis of NAFLD in the presence of gut-derived endotoxin.

Effect of Methyl Palmitate on the Formation of Epidural Fibrosis in an Experimental Epidural Fibrosis Model

ABSTRACTAim: To investigate the effects of local and systemic administration of methyl palmitate on the formation of epidural fibrosis. Material and Methods: Twenty-eight rats were randomly divided into four equal groups (control, Spongostan, local methyl palmitate and orally methyl palmitate) and laminectomy was performed between T11 and L1 in all rats. Local methyl palmitate (300 mg/kg) was applied with Spongostan; methyl palmitate (300 mg/kg) was given orally three times per week on different days for a total period of 4 weeks. Four weeks later, the vertebral column from T9 to L3, including the paraspinal muscles and epidural scar tissue, was removed en bloc and epidural fibrosis and arachnoidal involvement was graded and evaluated histopathologically. Kruskal-Wallis and Pearson Chi-Square test were used for statistical analysis. A statistically significant p-value was determined as p < 0.05. Results: The grading of epidural fibrosis was lower at a statistically significant level in orally-administrated methyl palmitate groups compared to the control and spongostan groups (p < 0.05). Conclusion: The findings of this study show that oral methyl palmitate decreases the formation of epidural fibrosis and that this effect of methyl palmitate could be mediated by reducing the functions of inflammatory cells such as macrophages, neutrophils and fibroblasts, including anti-inflammatory and antioxidant effects.

Alcohol and dual disorder. Paliperidone palmitate effectiveness

IntroductionAlcohol use is a common behavior in most people in our society. A first episode of alcoholism can be fully recovered through specialized treatment and other protective factors and need not become a relapse later.ObjectivesWhether there are differences in alcohol use after 1, 3 and 6 months after the administration of paliperidone palmitate extended-release injectable suspension in a sample of patients.Material and methodsThis is a descriptive study that analyzed the differences observed with respect to alcohol use after administration of paliperidone palmitate in a sample of 98 patients attending in a Mental Health Centre, in the Unit for drug dependency to present pathology dual.ResultsThe percentage of alcohol use at baseline is 56.1% of the total sample.One month after treatment with paliperidone palmitate the percentage of use is reduced to 31.6%. At 3 months of treatment the reduction is more significant assuming only the 6.1% of the total sample. Finally after 6 months of treatment the percentage of patients maintaining alcohol use is 4.1%, which represents a 52% reduction compared to the initial rate of use.ConclusionsThe data reflect a 92% reduction in alcohol use after 6 months of the administration of paliperidone palmitate.We can say that paliperidone palmitate is effective in reducing alcohol use in patients with dual diagnosis.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Rare but Treatment-emergent Extrapyramidal Symptoms-related Adverse Events after Administration of Long-acting Injectable Paliperidone Palmitate

Paliperidone palmitate, the long-acting injectable form of paliperidone (PLAI), is approved for once-monthly intramuscular injection [1]. Several studies suggest that the loading dose regimen for PLAI does not lead to higher rates of extrapyramidal symptoms (EPS)related treatment-emergent adverse events (TEAEs) than the oral formulation [2]. However, reports of post-injection delirium/sedation syndrome (PDSS) by olanzapine LAI raise safety issues of LAI. We report a case, which demonstrates that EPS-related TEAEs can be quite refractory to a number of pharmacological interventions and persist for more than 3 months following PLAI administration.

Satisfaction of immediate or delayed switch to paliperidone palmitate in patients unsatisfied with current oral atypical antipsychotics.

Patient satisfaction with treatment is an important clinical index associated with the efficacy and adherence of treatment in schizophrenia. Although switching from oral antipsychotics to the long-acting injectable formulation may improve convenience, patient satisfaction has not been studied extensively. We carried out a 21-week, multicenter, randomized, open-label comparative study. A total of 154 patients with schizophrenia unsatisfied with current oral atypical antipsychotics were assigned randomly to either immediate or delayed switching to paliperidone palmitate, the long-acting injectable formulation of paliperidone. The Medication Satisfaction Questionnaire (MSQ) and the Treatment Satisfaction Questionnaire for Medication (TSQM) were used to evaluate patient satisfaction with treatment, whereas the Positive and Negative Syndrome Scale (PANSS) and the Personal and Social Performance (PSP) scale were used to evaluate efficacy. From baseline to the final assessment, the MSQ score increased significantly in both groups, and the increase was greatest after the first administration of paliperidone palmitate in the immediate switch group. The scores of TSQM effectiveness, convenience, and global satisfaction as well as the PSP total score increased significantly, whereas the PANSS total score decreased significantly in both groups. The immediate switch group showed a significant improvement in the TSQM convenience score compared with the delayed switch group on oral antipsychotics during the comparison period. Most adverse events were minor and tolerable. In short, switching from oral atypical antipsychotics to paliperidone palmitate because of poor satisfaction significantly improved patient satisfaction, with comparable efficacy and tolerability.

Assesment of 28 days repeated adminstration toxicity profile of dexamethasone palmitate injection

Although, the dexamethasone have been used for the managements, against various ailments as single API or in combination with other drugs as acetate or palmitate salt. However, Dexamethasone as palmitate salt has not been investigated so far for sub acute toxicity on intravenous administration. Therefore, an attempt has been made to investigate sub-acute toxicity of dexamethasone palmitate injection. The drug was administered in experimental animals at different dose levels (0.07, 0.18 and 0.44 mg/kg, b.w.), for 28 days, and alteration in biochemical and haematological parameters was recorded along with histological examinations. The result data revealed that intravenous administration of dexamethasone palmitate does not causes any significant alteration in experimental animals examined at different levels. The observed changes were either well established adverse effects of Dexamethasone or were in laboratory reference range limit. The intravenous administered doses of drug were found safer, although somewhat adverse reactions may be observed at higher dose level (s). DOI: http://dx.doi.org/10.3126/jnpa.v27i1.12145 Journal of Nepal Pharmaceutical Association 2014 Vol.XXVII: 9-19

A retrospective analysis of inpatient utilization of paliperidone palmitate and readmission rates

Introduction: This study evaluated pharmacoeconomic considerations, specifically drug cost and patient readmission rates, of the non-formulary agent paliperidone palmitate, within the Alegent Creighton Health system. Pharmacy reimbursement rates for paliperidone palmitate are better on an outpatient versus inpatient basis. Given the low reimbursement rates for inpatient psychiatric care and the high cost of paliperidone palmitate, the drug cost could be justified if patients who received the injection demonstrated a subsequent reduction in readmission. Methods: The electronic medical record was used to identify patients who received at least one inpatient injection of paliperidone palmitate within the Alegent Creighton Health system from January 2010 – April 2012. Indication, dose, administration date, concurrent antipsychotics, length of stay (LOS), discharge date, and time to readmission were also recorded. Finance reports determined hospital cost and reimbursement for each inpatient stay and pharmacy cost of each paliperidone palmitate injection. Results: Thirty-two patients received paliperidone palmitate during the period specified. The average LOS was 18 days. The readmission rates for the paliperidone palmitate patients versus all patients at our institution with a diagnosis related group (DRG) of psychosis were as follows: within 30 days, 22% vs 12.5%; 60 days, 15% vs 15%; and 90 days, 25% vs 18%, respectively. The hospital experienced a net loss of roughly $5,610 per stay for the patients studied and paliperidone palmitate alone constituted approximately 16% of the total hospital cost per each patient stay. Discussion: In this limited patient population, it appears inpatient administration of paliperidone palmitate increased hospital cost without significantly reducing readmission rates at 30, 60, or 90 days post-injection. If patients are due for their monthly maintenance dose while hospitalized, the injection should be deferred to outpatient care if discharge is anticipated within one week since product labeling states maintenance injections can be given seven days after the monthly due date and outpatient reimbursement for the drug is superior.

Saturated Fatty Acid Palmitate Aggravates Neointima Formation by Promoting Smooth Muscle Phenotypic Modulation

Obesity is a major risk factor of atherosclerotic cardiovascular disease. Circulating free fatty acid levels are known to be elevated in obese individuals and, along with dietary saturated fatty acids, are known to associate with cardiovascular events. However, little is known about the molecular mechanisms by which free fatty acids are linked to cardiovascular disease. We found that administration of palmitate, a major saturated free fatty acid, to mice markedly aggravated neointima formation induced by carotid artery ligation and that the neointima primarily consisted of phenotypically modulated smooth muscle cells (SMCs). In cultured SMCs, palmitate-induced phenotypic modulation was characterized by downregulation of SMC differentiation markers, such as SM α-actin and SM-myosin heavy chain, and upregulation of mediators involved in inflammation and remodeling of the vessel wall, such as platelet-derived growth factor B and matrix metalloproteinases. We also found that palmitate induced the expression of proinflammatory genes via a novel toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor-κB/NADPH oxidase 1/reactive oxygen species signaling pathway: nuclear factor-κB was activated by palmitate via toll-like receptor 4 and its adapter, MyD88, and once active, it transactivated Nox1, encoding NADPH oxidase 1, a major reactive oxygen species generator in SMCs. Pharmacological inhibition and small interfering RNA-mediated knockdown of the components of this signaling pathway mitigated the palmitate-induced upregulation of proinflammatory genes. More importantly, Myd88 knockout mice were resistant to palmitate-induced exacerbation of neointima formation. Palmitate seems to promote neointima formation by inducing inflammatory phenotypes in SMCs.

γ-Oryzanol recovers mouse hypoadiponectinemia induced by animal fat ingestion

Adiponectin is an insulin-sensitizing adipocyte-derived adipokine. The decrease in plasma adiponectin level (hypoadiponectinemia) is involved in the development of insulin resistance and the resulting type 2 diabetes. Our previous studies have demonstrated that γ-oryzanol (ORZ) from rice bran suppressed NF-κB activation and increased adiponectin secretion from adipocyte. In this study, we have evaluated effects of oral administration of animal fat (beef tallow) and palmitate on mouse serum adiponectin level. Oral administrations of beef tallow and palmitate significantly suppressed serum adiponectin levels into around half of the initial level from 48 to 96 h after administration compared with the case of corn oil (P<0.05). Coadministration of ORZ successfully remedied mouse hypoadiponectinemia induced by ingestion of beef tallow and the relative adiponectin levels attained to 1.66±0.23 at 96 h after administration (mean value±s.e., P<0.05). Diverse physiological functions of ORZ in crop bran might be promising us to prevent chronic inflammations in the pathogeneses of the metabolic or insulin resistance syndromes.

Peroxisome proliferator-activated receptor-γ protects ERBB2-positive breast cancer cells from palmitate toxicity

IntroductionAccumulation of fatty acids and neutral lipids in nonadipose tissues is cytotoxic. We recently showed that ERBB2-positive breast cancer cells produce significantly high amounts of fats, because of overexpression of the peroxisome proliferator-activated receptor (PPAR)γ-binding protein and the nuclear receptor NR1D1 (nuclear receptor subfamily 1, group D, member 1; Rev-erbα). These genes upregulate de novo fatty acid synthesis, which is a critical pathway for the energy production and survival of these cells. NR1D1 and PPARγ-binding protein are functionally related to PPARγ, a well established positive regulator of adipogenesis and lipid storage.MethodsThe effects of GW9662 and exogenously added palmitate on breast cells (BT474, MDA-MB-361, MCF-7, and human mammary epithelial cells) in monolayer culture were assessed. Mass spectrometric quantitation of fatty acids and fluorescence-based high content microscopy assays of cell growth, apoptosis, triglyceride storage and reactive oxygen species production were used.ResultsERBB2-positive breast cancer cells are more sensitive to inhibition of PPARγ activity by the antagonist GW9662. PPARγ inhibition results in increased levels of total fats in the cells, mostly because of increased amounts of palmitic and stearic unsaturated acids. Administration of exogenous palmitate is lethal to ERBB2-positive but not to ERBB2-negative cells. GW9662 exacerbates the effects of palmitate addition on BT474 and MDA-MB-361 cells, but it has no significant effect on MCF-7 and human mammary epithelial cells. Palmitate administration results in a fivefold to tenfold greater increase in fat stores in ERBB2-negative cells compared with ERBB2-positive cells, which suggests that the ERBB2-positive cells have maximized their ability to store fats and that additional palmitate is toxic to these cells. Both PPARγ inhibition and palmitate administration result in increased reactive oxygen species production in BT474 cells. The cell death that results from this treatment can be counteracted by the antioxidant N-acetyl cysteine.ConclusionsOur findings indicate that PPARγ activity enables ERBB2-positive breast cancer cells, which produce high levels of fat, to convert fatty acids to triglycerides, allowing these cells to avert the cell death that results from lipotoxicity. Endogenous palmitate toxicity represents a genetically based property of ERBB2-positive breast cancer that can be exploited for therapeutic intervention.

One-Year Follow-up of Very Preterm Infants Who Received Lucinactant for Prevention of Respiratory Distress Syndrome: Results From 2 Multicenter Randomized, Controlled Trials

The benefits of exogenous surfactants for prevention or treatment of respiratory distress syndrome are well established, but there is a paucity of long-term follow-up data from surfactant-comparison trials. We sought to determine and compare survival and pulmonary and neurodevelopmental outcomes through 1 year corrected age of preterm infants who received lucinactant and other surfactants in the SELECT (Safety and Effectiveness of Lucinactant Versus Exosurf in a Clinical Trial) and STAR (Surfaxin Therapy Against Respiratory Distress Syndrome) trials individually and, secondarily, from analysis using combined data from these 2 trials. All infants from both trials who were randomly assigned to administration of lucinactant (175 mg/kg), colfosceril palmitate (67.5 mg/kg), beractant (100 mg/kg), or poractant alfa (175 mg/kg) were prospectively followed through 1 year corrected age, at which point masked assessment of outcomes was performed for surviving infants. One-year survival was a key outcome of interest. Other parameters assessed included rates of rehospitalization and respiratory morbidity and gross neurologic status. Data were analyzed by comparing the different surfactants within each trial and, in secondary analysis, combining data from both trials to compare lucinactant versus the animal-derived surfactants (beractant and poractant) used in these trials. Survival rates over time were compared by using the Wilcoxon test for survival through 1 year corrected age and logistic regression for comparison of fixed time points. The latter analyses were performed by using the prespecified approach, where loss to follow-up or withdrawal of consent was imputed as a death, and also using raw data. Other outcomes were analyzed by using the Cochran-Mantel-Haenszel test or logistic regression for categorical data, and analysis of variance on ranks was used for continuous data. Very few cases were lost to follow-up in either trial (29 of 1546 enrolled in both trials [1.9%]). In the primary analysis of the SELECT trial comparing lucinactant to either colfosceril or beractant, there were no significant differences in the proportion of infants who were alive through 1 year corrected age. Fixed-time-point estimates of mortality at 1 year corrected age imputing loss to follow-up as a death were 28.1% for lucinactant, 31.0% for colfosceril, and 31.0% for beractant. By using raw data without imputing loss to follow-up as a death, mortality estimates at 1 year corrected age were computed to be 26.6%, 29.1%, and 28.3%, respectively. In the primary analysis of the STAR trial, significantly more infants treated with lucinactant were alive through 1 year corrected age compared with those who received poractant alfa. Fixed time estimates of mortality at 1 year corrected age imputing loss to follow-up as a death were 19.4% for lucinactant and 24.2% for poractant. These estimates using raw data that did not impute loss to follow-up as a death were 18.6% and 21.9%, respectively. In the combined analysis, survival through 1 year corrected age was higher for infants in the lucinactant group versus that of the infants in the animal-derived surfactants (beractant and poractant) group. The fixed-time-point estimates of mortality at 1 year corrected age imputing loss to follow-up as a death for lucinactant and animal-derived surfactants were 26.0% and 29.4%, respectively. However, the 1-year-corrected-age estimates using combined raw data were 24.6% for the lucinactant group and 26.7% for the animal-derived surfactant group. The incidence of postdischarge rehospitalizations, total number of rehospitalizations, incidence of respiratory illnesses, and total number of respiratory illnesses were generally similar among those in the treatment groups. Neurologic status at 1 year corrected age was essentially similar between infants who received lucinactant and those who received all other surfactants used in these 2 trials. Findings from this 1-year follow-up of both lucinactant trials indicate that this new peptide-based synthetic surfactant is at least as good, if not superior, to animal-derived surfactants for prevention of respiratory distress syndrome and may be a viable alternative to animal-derived products.

The Leucocytic and Parasitaemic Profiles and Immune Response of Rats Treated with Retinyl Palmitate before Infection with Trypanosoma brucei

The effects of oral administration of retinyl palmitate (30 000 IU/kg bodyweight) for 3 days to rats before infection with Trypanosoma brucei were investigated by examining the leucocytic and parasitaemic profiles, and the antibody response to sheep red blood cells. The pretreatment significantly ( P<0.01) improved the leucocytic profile (especially the absolute lymphocyte count) from day 7 post-infection to the time of death. It also significantly delayed the onset of parasitaemia (i.e., lengthened the pre-patent period) and led to reduced levels of parasitaemia throughout the period of infection. Pretreatment significantly increased the antibody response to sheep red blood cells ( P<0.01) throughout the infection, even after treatment with diminazene aceturate, to levels that more than compensated for the immunosuppressive effect of the T. brucei. Further studies are warranted on the possible use of retinyl palmitate in overcoming immunosuppression associated with trypanosome infections in man and animals in endemic areas.

Reduction of blood loss by infusion of human platelets in a rabbit kidney injury model

As a first step toward testing the efficacy of stored platelets or platelet substitutes in vivo, a kidney injury model was developed to assess the hemostatic properties of human platelets in normal and thrombocytopenic rabbits. New Zealand white rabbits were made thrombocytopenic by two consecutive injections of busulfan. Two weeks later, human platelets were transfused to animals whose reticuloendothelial systems were inhibited by the administration of ethyl palmitate. The left kidney was exposed and a slice excised from the anterior pole. The blood was contained in a parafilm boat and absorbed by preweighed gauze to assess blood loss. The percentage of human platelets transfused to the rabbit was determined by flow cytometry on blood collected from the cut site using anti-CD42a (marker for human platelets). The degree of activation of the human platelets was determined using anti-CD62a (marker specific for human p-selectin). Blood loss was similar in normal animals treated with saline alone (35.4 +/- 5.8 g; n = 4); ethyl palmitate and saline (42.5 +/- 5.7 g; n = 6, p = 0.4); or ethyl palmitate and fresh human platelets (45.7 +/- 7.9 g; n = 6, p = 0.3). Bleeding in thrombocytopenic rabbits infused with saline was increased (75.6 +/- 3.9 g; n = 7) as compared with nonthrombocytopenic animals. A significant reduction in blood loss was noted in thrombocytopenic rabbits given fresh human platelets (51.6 +/- 4.5 g; n = 6, p = 0.0023). Transfusion of human platelets to rabbits did not cause activation of the platelets. Furthermore, transfusion of thrombin-activated platelets (60-98% activated) to thrombocytopenic rabbits reduced blood loss (54 +/- 7.3 g; n = 7) to the same extent as fresh platelets. This is the first report describing a kidney injury model developed to assess the efficacy of fresh and activated human platelets in reducing blood loss in thrombocytopenic rabbits. This model could monitor the efficacy of human platelets prepared by various preservation protocols in suppressing bleeding in rabbits.

Survival of fresh human platelets in a rabbit model as traced by flow cytometry.

In the event of hemorrhage and blood loss, platelets play a vital role in the coagulation process. However, there are currently no acceptable protocols for long-term storage of platelets. As a first step toward testing the efficacy of stored platelets or platelet substitutes in vivo, a flow cytometric technique was developed to detect human platelets in rabbit blood. Human platelets were transfused to rabbits whose reticuloendothelial system was inhibited by the administration of ethyl palmitate. Because human and rabbit platelets display surface molecules with different epitopes, human platelets were selectively labeled with antibodies specific for glycoprotein IX (CD42a). As this antibody does not label rabbit platelets, it allows discrimination of human from rabbit platelets in samples of rabbit blood containing both types of platelets. Survival of human platelets in rabbits was monitored by flow cytometry and fluorescence microscopy in blood drawn at various times after the platelet transfusion. Fresh human platelets transfused to untreated control rabbits (n = 3) were removed from circulation within 10 minutes of the completion of the transfusion. Fresh platelets (1 day old) transfused to rabbits treated with ethyl palmitate (n = 5) survived for 24 hours with an average half-life of 8.6 hours. In contrast, 8-day-old platelets were cleared from the circulation sooner with an average half-life of 2.9 hours (n = 4). This report describes a rapid and efficient method of assessing the survival of human platelets in a rabbit model using flow cytometry. This technique will enable the monitoring in rabbits of human platelets prepared by various preservation protocols.

Interferon-β, Retinoids, and Tamoxifen in the Treatment of Metastatic Breast Cancer: A Phase II Study

Based on the additive or synergistic antiproliferative effect of interferon and tamoxifen on breast cancer cell lines and on preclinical and clinical data on retinoids alone and in combination with antiestrogen or interferon, we designed a pilot phase II study to test the toxicity of simultaneous administration of interferon-beta (IFN-beta), retinoids (R), and tamoxifen (TAM) and the efficacy of this combination as salvage therapy in a group of patients with metastatic breast cancer (MBC). A total of 49 stage IV breast cancer patients, 11 pretreated with hormones, 26 with chemotherapy, and 12 with both, received 30 mg TAM and two dose levels of IFN-beta and retinyl palmitate. Among 49 evaluable patients, 27 achieved a clinical response (55%; 95% CI 41-69%), 10 had stable disease (20%), and in 12 (25%) the disease progressed. Toxicity with both dose levels was moderate and mainly hepatic. Median response duration, not statistically different in estrogen receptor-positive and negative patients, was 31.4 months (range 4.9-67). Median overall survival was 19.2 months (range 2-69). We have shown that long-term administration of TAM, IFN-beta, and retinyl palmitate is feasible with moderate toxicity. We have also demonstrated that this regimen is active in pretreated MBC patients and that responses are not influenced by receptor status.