Factors associated with the quality of life of nursing home residents in Hong Kong.

BACKGROUND: The quality of life of nursing home residents has increasingly become an important dimension when evaluating care in a nursing home. Not a lot is known about the quality of life of nursing home residents in Hong Kong. AIM: To investigate factors associated with the quality of life of nursing home residents to inform care management policies and service delivery. METHODS: This study reports data from 125 nursing home residents. The Hong Kong Chinese version of the World Health Organization's Quality of Life-Brief version was used. Other measures used include the Mini-Mental State Examination, the Mini-Nutritional Assessment, the Geriatric Depression Scale, the Modified STRATIFY Falls Prediction Tool and the Modified Barthel Index. A univariate analysis and a multiple regression analysis were then performed to identify the influencing factors. RESULTS: The participants reported a moderate level of quality of life, with the exception in the domain of social relationships. A univariate analysis found some associations between demographic and clinical characteristics and quality of life. A multiple regression analysis indicated that pain, being younger (65-74 years), having son(s) or daughter(s), and cognitive impairment were negatively associated factors. LIMITATIONS: The smallness of the sample from a single study site limits the generalizability of the findings. CONCLUSION: This study provides information that has hitherto been lacking on the quality of life and associated factors among local nursing home residents in Hong Kong. The preliminary findings can help healthcare staff to identify those at risk of suffering from a low quality of life and to design appropriate care interventions to improve the quality of life of such residents. IMPLICATIONS: Adequate pain relief, family connectedness and special attention to the needs of those with cognitive impairment are important considerations in ensuring a better quality of life for older people in long-term residential care.

Microwave-assisted extraction of active pharmaceutical ingredient from solid dosage forms.

The microwave assisted extraction (MAE) technique has been evaluated for the extraction of active pharmaceutical ingredients (API) from various solid dosage forms. Using immediate release tablets of Compound A as a model, optimization of the extraction method with regards to extraction solvent composition, extraction time and temperature was briefly discussed. Complete recovery of Compound A was achieved when samples were extracted using acetonitrile as the extraction solvent under microwave heating at a constant cell temperature of 50 degrees C for 5 min. The optimized MAE method was applied for content uniformity (single tablet extraction) and potency (multiple tablets extraction) assays of release and stability samples of two products of Compound A (5 and 25mg dose strength) stored at various conditions. To further demonstrate the applicability of MAE, the instrumental extraction conditions (50 degrees C for 5 min) were adopted for the extraction of montelukast sodium (Singulair) from various solid dosage forms using methanol-water (75:25, v/v) as the extraction solvent. The MAE procedure demonstrated an extraction efficiency of 97.4-101.9% label claim with the greatest RSD at 1.4%. The results compare favorably with 97.6-102.3% label claim with the greatest RSD at 2.9% obtained with validated mechanical extraction procedures. The system is affordable, user-friendly and simple to operate and troubleshoot. Rapid extraction process (7 min/run) along with high throughput capacity (up to 23 samples simultaneously) would lead to reduced cycle time and thus increased productivity.

Suppression of intestinal polyps in Msh2-deficient and non-Msh2-deficient multiple intestinal neoplasia mice by a specific cyclooxygenase-2 inhibitor and by a dual cyclooxygenase-1/2 inhibitor.

Epidemiological studies suggest that nonsteroidal anti-inflammatory agents decrease the risk of colorectal cancer. This is believed to be mediated, at least in part, by inhibition of cyclooxygenase (COX) activity. There are two COX isoenzymes, namely the constitutively expressed COX-1 and the inducible COX-2. COX-2 is overexpressed in adenomas and colorectal cancers, and COX-2-specific inhibitors have been shown to inhibit intestinal polyps in Apc(Delta716) mice more effectively than dual COX-1/COX-2 inhibitors such as sulindac. Various Apc knockout mice, including the multiple intestinal neoplasia (Min) mouse and the Apc(Delta716) mouse, are limited by their lack of large numbers of colonic adenomas and aberrant crypt foci, the putative precursors of large-bowel polyps and cancers. Our DNA mismatch-repair-deficient Min mouse model (Apc+/-Msh2-/-) has genetic features of both familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, and most importantly, rapidly develops numerous small- and large-bowel adenomas, as well as colonic aberrant crypt foci. The purpose of this study was to determine the effects of COX inhibitors on intestinal adenomas and colonic aberrant crypt foci in this accelerated polyposis, mismatch-repair-deficient Min mouse model, in addition to a standard Min mouse model. Weanling Apc+/-Msh2-/- and Min mice were fed diets containing no drug, sulindac, or a specific COX-2 inhibitor (MF-tricyclic). Apc+/-Msh2-/- and Min mice were sacrificed after 4 weeks and 5 months on diet, respectively. Apc+/-Msh2-/- mice treated with MF-tricyclic had significantly fewer small-bowel polyps (mean +/- SD, 178 +/- 29) compared with mice on sulindac (278 +/- 80), or control diet (341 +/- 43; P < 0.001). There was no difference in numbers of large-bowel polyps or aberrant crypt foci in mice in the three groups. MF-tricyclic was also effective in reducing both small- and large-bowel polyps in Min mice. Western analysis demonstrated COX-2 expression in both large- and small-bowel polyps from mice of both genotypes. This study demonstrates that a specific COX-2 inhibitor is effective in preventing small-bowel polyps in mismatch-repair-deficient Min mice and both small- and large-bowel polyps in standard Min mice. Therefore, specific COX-2 inhibitors may be useful as chemopreventive and therapeutic agents in humans at risk for colorectal neoplasia.

Chemoprevention of intestinal polyposis in the Apcdelta716 mouse by rofecoxib, a specific cyclooxygenase-2 inhibitor.

Mutations in the human adenomatous polyposis (APC) gene are causative for familial adenomatous polyposis (FAP), a rare condition in which numerous colonic polyps arise during puberty and, if left untreated, lead to colon cancer. The APC gene is a tumor suppressor that has been termed the "gatekeeper gene" for colon cancer. In addition to the 100% mutation rate in FAP patients, the APC gene is mutated in >80% of sporadic colon and intestinal cancers. The Apc gene in mice has been mutated either by chemical carcinogenesis, resulting in the Min mouse Apcdelta850, or by heterologous recombination, resulting in the Apcdelta716 or Apedelta1368 mice (M. Oshima et al., Proc. Natl. Acad. Sci. USA, 92: 4482-4486, 1995). Although homozygote Apc-/- mice are embryonically lethal, the heterozygotes are viable but develop numerous intestinal polyps with loss of Apc heterozygosity within the polyps (M. Oshima et al., Proc. Natl. Acad. Sci. USA, 92: 4482-4486, 1995). The proinflammatory, prooncogenic protein cyclooxygenase (COX)-2 has been shown to be markedly induced in the Apcdelta716 polyps at an early stage of polyp development (M. Oshima et al., Cell, 87: 803-809, 1996). We demonstrate here that treatment with the specific COX-2 inhibitor rofecoxib results in a dose-dependent reduction in the number and size of intestinal and colonic polyps in the Apcdelta716 mouse. The plasma concentration of rofecoxib that resulted in a 55% inhibition of polyp number and an 80% inhibition of polyps > 1 mm in size is comparable with the human clinical steady-state concentration of 25 mg rofecoxib (Vioxx) taken once daily (A. Porras et al., Clin. Pharm. Ther., 67: 137, 2000). Polyps from both untreated and rofecoxib- or sulindac-treated Apcdelta716 mice expressed COX-1 and -2, whereas normal epithelium from all mice expressed COX-1 but minimal amounts of COX-2. Polyps from either rofecoxib- or sulindac-treated mice had lower rates of DNA replication, expressed less proangiogenic vascular endothelial-derived growth factor and more membrane-bound beta-catenin, but showed unchanged nuclear localization of this transcription factor. This study showing the inhibition of polyposis in the Apcdelta716 mouse suggests that the specific COX-2 inhibitor rofecoxib (Vioxx) has potential as a chemopreventive agent in human intestinal and colon cancer.

Frailty, pain and psychological variables among older adults living in Hong Kong nursing homes: can we do better to address multimorbidities?

WHAT IS KNOWN ON THE SUBJECT?: Frailty and multimorbidity are common in later life. A higher level of frailty is associated with a higher risk of adverse physical and psychological health situations. Older adults with pain have been reported to be lonelier and more depressed, as well as less happy and less satisfied with their life as compared to those without pain. In view of the high prevalence of pain among older adults and the reversibility of frailty, it is important to explore the relationship between pain, frailty and psychological parameters in order to devise patient-centred interventions. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: Frailty index is positively correlated with the presence of pain, and associated with gender, functional mobility and loneliness. Among these significant variables, loneliness was the factor that contributed the most to the frailty index. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: It is essential to put the focus of healthcare on both the physical and psychological aspects of well-being. All nurses are advised to improve the management of pain in older people in order to lower the levels of pain, frailty and psychological distress among this population. Nursing care should address the loneliness level especially the problem of social loneliness among older adults particularly those living in nursing homes. ABSTRACT: Introduction In view of the high prevalence of pain among older adults and the reversibility of frailty, it is important to explore the relationship between pain, frailty and psychological parameters in order to devise patient-centred interventions. Aim To examine the levels of frailty, pain and psychological parameters among older adults living in Hong Kong nursing homes, and the cross-sectional relationships among these items. Methods A cross-sectional study was conducted among 178 residents from six nursing homes. Frailty, pain, mobility, happiness, loneliness and life satisfaction of participants were assessed using validated questionnaires. Results A multiple linear regression (R(2)  = 0.338, P < 0.05) showed that the frailty index was associated with loneliness, functional mobility and gender. Among these significant variables, loneliness was the factor that contributed the most to the frailty index. Discussion It is essential to put the focus of healthcare on both the physical and psychological aspects of well-being. Findings suggest that apart from improving mobility and reducing pain, loneliness could be a target of psychosocial interventions to reduce frailty and improve quality of life. Implications for practice It is advised that nursing care should address loneliness, especially the problem of social loneliness among older adults particularly those living in nursing homes.

Recognition of tetrahedral 1,10-phenanthroline-cuprous chelates by transcriptionally active complexes does not depend on the sequence of the promoter.

BACKGROUND: The open complex formed at the initiation site of transcription within the active site of RNA polymerase is unique to actively transcribing genes and is thus an ideal target for the design of transcription inhibitors. Many redoxactive tetrahedral cuprous chelates of 1,10-phenanthroline (OP) or derivatives cleave the single-stranded template, principally at sequence positions -7 to -3, whereas the redox-inactive tetrahedral cuprous chelate of 2, 9-dimethyl-OP (neocuproine) blocks transcription, but does not cleave. The octahedral (OP)3-Fe2+ chelate has no effect. Different promoters can give different cleavage patterns. We therefore searched for structural determinants of the open complex that are important in the cleavage reaction. RESULTS: Using site-directed mutagenesis, we systematically altered the nucleotides at the cleavage sites of the Escherichia coli lac UV-5-RNA polymerase open complex (positions -6 to -4), which are highly variable in E. coli promoters. Surprisingly, these changes had little effect on catalytic activity, on transcription inhibition by the cuprous complex of neocuproine and on the cleavage patterns generated by the cuprous chelates of OP derivatives. The scission pattern of a lac UV-5 promoter mutant in which the cleavage sites have the sequence of the trp EDCBA promoter is that of the lac UV-5 promoter, not the trp EDCBA promoter. CONCLUSIONS: Nucleotide-specific interactions are not responsible for the observed cleavage patterns. The recognition of the tetrahedral OP chelate must be due to a specific structure of the single-stranded regions, determined by RNA polymerase-DNA interactions in the upstream regulatory region.

Human NELL-1 expressed in unilateral coronal synostosis.

Surgical correction of unilateral coronal synostosis offers a unique opportunity to examine the molecular differences between an abnormal and a normal cranial suture. We isolated and identified a cDNA fragment whose expression was up-regulated in the premature fusing and fused coronal sutures, as compared with normal coronal sutures. The nucleotide sequence of the full-length cDNA of this gene, human NELL-1, has approximately 61% homology with the chicken Nel gene. Both chicken Nel and human NELL-1 are comprised of six epidermal growth factor-like repeats. The human NELL-1 messages were localized primarily in the mesenchymal cells and osteoblasts at the osteogenic front, along the parasutural bone margins, and within the condensing mesenchymal cells of newly formed bone in sites of premature sutural fusion. Human multiorgan tissue mRNA blot showed that NELL-1 was specifically expressed in fetal brain but not in fetal kidney, liver, or lung. We also showed that Nell-1 was expressed in rat calvarial osteoprogenitor cells and was largely absent in rat tibiae and fibroblast cell cultures. In conclusion, our data suggest that the NELL-1 gene is preferentially expressed in cranial intramembranous bone and neural tissue (both of neural crest cell origin) and is up-regulated during unilateral premature closure of the coronal suture. The precise role of this gene is unknown.

Pleurectomy and intraoperative brachytherapy and postoperative radiation in the treatment of malignant pleural mesothelioma.

Forty-one patients with diffuse, pleural mesothelioma limited to one hemi-thorax underwent a thoracotomy at Memorial Sloan-Kettering Cancer Center from January 1976 to July 1982. Treatment at thoracotomy consisted of as complete a parietal pleurectomy as was possible to remove the bulk of the tumor. Measurable gross residual disease was treated whenever feasible, with permanent 125I implantation; residual diffuse disease was treated by a temporary 192Ir implantation or by postoperative instillation of 32P. External radiation therapy was given 4-6 weeks postoperatively to the involved hemi-thorax, shielding the lung and utilizing a combination of electron and a photon beam. A dose of 4500 rad in 4.5 weeks was given to the pleural surface by the mixed beam. There was no postoperative mortality in this group of 41 patients. Complications developed in 6 patients (15%). The median survival was 21 months; the one year survival was 65% and the two year survival was 40%. The median disease-free survival was 11 months and the one and two year disease-free survival 44 and 13% respectively. This study suggests that the combination of pleurectomy, intraoperative brachytherapy and postoperative external radiation increased the local control of the tumor and prolonged the survival.

Intra-operative iodine-125 prostatic implant following bilateral pelvic lymphadenectomy.

Sixty-five patients with prostatic adenocarcinoma Stages B and C were treated with intraoperative Iodine-125 prostatic implantation following bilateral pelvic lymphadenectomy. Pelvic nodal metastases were found in 31% of the patients: 23% (7/31) in clinical Stage B1 disease, 29% (8/28) in clinical Stage B2, and 83% (5/6) in clinical Stage C. All the patients have been followed for a period of 1 1/2 to 6 years. Serial digital rectal examination revealed complete regression of the palpable disease in 15% of the patients at 6 months, 47% at 1 year, and 87% at 2 years. Post-operative complications were also evaluated: 13% of the patients became sexually impotent, 11% had impaired potency after the procedure, and 16% of patients complained of dry ejaculation; and 17% developed scrotal and/or penile swelling, which persisted up to 14 months, but usually subsided within 5 months. Two patients developed local recurrence. Both patients responded to subsequent external radiation therapy of 7000 rad in 11 to 14 weeks with clinical regression of palpable disease.

Substituted (pyridylmethoxy)naphthalenes as potent and orally active 5-lipoxygenase inhibitors; synthesis, biological profile, and pharmacokinetics of L-739,010.

Dioxabicyclooctanyl naphthalenenitriles have been reported as a class of potent and nonredox 5-lipoxygenase (5-LO) inhibitors. These bicyclo derivatives were shown to be metabolically more stable than their tetrahydropyranyl counterparts but were not well orally absorbed. Replacement of the phenyl ring in the naphthalenenitrile 1 by a pyridine ring leads to the potent and orally absorbed inhibitor 3g (L-739,010, 2-cyano-4-(3-furyl)-7-[[6-[3-(3-hydroxy-6,8-dioxabicyclo[3.2.1] octanyl)]-2-pyridyl]methoxy]naphthalene). Compound 3g inhibits 5-HPETE production by human 5-LO and LTB4 biosynthesis by human PMN leukocytes and human whole blood (IC50S of 20, 1.6, and 42 nM, respectively). Derivative 3g is orally active in the rat pleurisy model (inhibition of LTB4, ED50 = 0.3 mg/kg) and in the anesthetized dog model (inhibition of ex vivo whole blood LTB4 and urinary LTE4, ED50 = 0.45 and 0.23 microgram/kg/min, respectively, i.v. infusion). In addition, 3g shows excellent functional activity against ovalbumin-induced dyspnea in rats (60% inhibition at 0.5 mg/kg, 4 h pretreatment) and Ascaris-induced bronchoconstriction in conscious sheep (50% and > 85% inhibition in early and late phases, respectively at 2.5 micrograms/kg/min, i.v. infusion) and, more particularly in the conscious antigen sensitive squirrel monkey model (53% inhibition of the increase in RL and 76% in the decrease of Cdyn, at 0.1 mg/kg, po). In rats and dogs, 3g presents excellent pharmacokinetics (estimated half-lives of 5 and 16 h, respectively) and bioavailabilities (26% and 73% when dosed as its hydrochloride salt at doses of 20 and 10 mg/kg, respectively, in methocel suspension). Based on its overall biological profile, compound 3g has been selected for preclinical animal toxicity studies.

Activity-dependent and use-dependent regulation of dopamine-receptor clustering.

In this study, fluorescence-conjugated ligands were employed to label dopaminergic D1-like and D2-like receptors, respectively, in neurons derived from the frontal cortex of embryonic rats. The receptor binding sites were visualized and analyzed using confocal microscopy. Our results showed that fluorescently labeled receptors tended to form clusters with a diameter of about one micrometer and were distributed on both somata and dendrites. Chronic treatment with tetrodotoxin reduced the number of fluorescent clusters of both D1-like and D2-like receptors, while chronic treatment with a high concentration of potassium increased the number of fluorescent clusters of both D1-like and D2-like receptors. Further, chronic treatment with SCH23390 up-regulated the number of D1-like receptor clusters, whereas chronic treatment with bromocriptine down-regulated the number of D2-like receptor clusters. In addition, chronic treatment with spiperone down-regulated the number of D1-like receptor clusters. These results suggest that both neuronal activity and dopaminergic receptor occupancy are important factors that determine dopaminergic receptor clustering which is an essential step toward synaptogenesis during neuronal maturation process.

Permeability of the peptidic GH secretagogues hexarelin and EP 51389, across rat jejunum.

The intestinal permeability of hexarelin and EP 51389, two growth hormone releasing hexa- and tri- peptide analogues, was assessed in vitro with side-by-side diffusion chambers in the apical-to-basolateral (AP-to-BL) and in the basolateral-to-apical (BL-to-AP) direction using excised rat jejunal segments. The effect of EP 51389 on P-glycoprotein (P-gp) was evaluated by rhodamine 123 accumulation on monolayers of CH(R)C5 cells with increasing concentrations of EP 51389. Hexarelin and EP 51389 permeability were found to be < 1%. Permeability coefficients (P(app)) were 18.87 +/- 2.86 (x10(-7) cm/s) and 5.87 +/- 0.45 (x10(-7) cm/s) for hexarelin and EP 51389, respectively. Bidirectional studies revealed that hexarelin transport was similar in both directions. EDTA did not influence hexarelin permeability. Permeability was predominantly secretory for EP 51389 as P(app) in the BL-to-AP direction [32.56 +/- 6.11 (x10(-7) cm/s)] was greater than AP-to-BL. Confirming involvement of a secretory transport system, chlorpromazine inhibited EP 51389 transport across the jejunum. EP 51389 inhibited P-gp in a dose dependent manner resulting in the intracellular accumulation of rhodamine in CH(R)C5 cells. These results suggest that: 1) the intestinal permeability of hexarelin and EP 51389 is poor; 2) the passage of hexarelin is mainly via a transcellular passive pathway since the contribution of paracellular permeability to the overall permeability is rather low; 3) P-gp may act as a potential barrier for the intestinal absorption of EP 51389.

Aspartate aminotransferase isoenzymes--differential kinetic assay in serum.

The isoenzymes of aspartate transaminase differ in their kinetic properties in that the cytoplasmic isoenzyme is more readily inhibited by adipate and by 2-oxoglutarate (substrate) at low pH. A differential kinetic assay based on this phenomenon has been optimised for use in assays of serum samples. The new method agrees well with an immune absorption procedure. Methods based on chromatographic separation of the isoenzymes fail in the presence of serum.

Fluorometric determination of nanogram quantities of protein in small samples: application to calcium-transport adenosine triphosphatase.

A fluorometric micro protein assay based on fluorescamine-labelling of homogeneous proteins in solution has been developed which is capable of accurately quantitating as little as 25 ng protein at a concentration of 1.25 micrograms/ml. This micro assay uses a flow-through HPLC fluorescence detector. Typical micro assays measuring bovine serum albumin standards (0-25 mg/l) yielded linear regression coefficients of r = 0.999. Assays of purified Ca2+-ATPase solutions determined by the micro fluorescamine procedure correlated well with measurements made using the deoxycholate-TCA-precipitation modification of the Lowry assay: 1.0 microgram ATPase by Lowry method = 1.1 microgram protein by fluorescamine microassay (when both procedures were standardized with bovine serum albumin) (r = 0.995). The assay proposed offers a 100-fold increase in sensitivity, compared to the Lowry procedure.

Alteration in the disposition and metabolism of S(-)-propranolol in rats with active respiratory viral infection.

Viral illness elicited marked changes in the disposition and metabolism of S(-)-propranolol in rats during the course of a recent viral outbreak in our rodent colony. A slower rate of gastrointestinal absorption and a much higher clearance of orally-administered S(-)-propranolol were observed. The apparent increase in metabolic clearance is partly attributed to a decrease in the serum protein binding of S(-)-propranolol. A direct stimulation of microsomal oxidative metabolism was also suggested by an increase in urinary recovery of the monohydroxyl metabolites of S(-)-propranolol. In addition, a greater portion of the phenolic metabolites were present in urine as the glucuronic acid conjugates, which may be explained by a concomitant stimulation in conjugative reaction. These observations are unusual in that existing reports indicate that viral illness in man and animals generally leads to an inhibition of oxidative drug metabolism.

HPLC analysis of indomethacin and its impurities in capsule and suppository formulations.

Indomethacin and its impurities in suppository and capsule formulations were quantitatively determined by HPLC using a reversed-phase, octadecyl column and a mobile phase of methanol-water-acetonitrile-acetic acid (55:35:10:1). Analysis of the suppository formulations provided a mean potency for indomethacin of 103.8%. The same formulation was found to contain 4-chlorobenzoic acid (0.02%), 5-methoxy-2-methyl-3-indoleacetic acid (0.07%), 4-chlorobenzoic acid-alpha-monoglyceride (0.39%), and indomethacin-alpha-monoglyceride (0.9%) as impurities. The latter two impurities were a result of the interaction of indomethacin and 4-chlorobenzoic acid with glycerin used in the suppository base. Capsule formulations were likewise assayed with an average potency of 99.9 and 101.5% for 25- and 50-mg dosage forms, respectively. Only one of the two capsule formulations examined contained detectable quantities of 4-chlorobenzoic acid (0.05%).

Cyclosporine A transfer between high- and low-density lipoproteins: independent from lipid transfer protein I-facilitated transfer of lipoprotein-coated phospholipids because of high affinity of cyclosporine a for the protein component of lipoproteins.

The objectives of this study were to determine if lipid transfer protein I (LTP I)-facilitated phospholipid (PC) transfer activity regulates the plasma lipoprotein distribution of cyclosporine (CSA) and if the association of CSA with high-density lipoproteins (HDL) is due to the high protein and/or alterations in coat lipid content of HDL. To assess if LTP I-facilitated PC transfer activity regulates the plasma lipoprotein distribution of CSA, (14)C-PC- or (3)H-CSA-enriched HDL or low-density lipoproteins (LDL) were incubated in T150 buffer [pH 7.4, containing a (14)C-PC- or (3)H-CSA-free lipoprotein counterpart +/- exogenous LTP I (1.0 microg protein/mL)] or in delipidated human plasma that contained 1.0 microg protein/mL of endogenous LTP I in the presence or absence of a monoclonal antibody TP1 (30 microg protein/mL) directed against LTP I for 90 min at 37 degrees C. To assess the influence of HDL subfraction lipid composition and structure on the plasma distribution of CSA, CSA at 1000 ng of drug/mL of plasma was incubated in human plasma pretreated for 24 h with a lecithin:cholesterol acyltransferase (LCAT) inhibitor, dithionitrobenzoate (DTNB; 3 mM). To assess the binding of CSA to apolipoproteins AI, AII, and B, increasing concentrations of CSA were added to a constant concentration of either apolipoprotein AI, AII, or B. Equilibrium dialysis was used to determine free and bound fractions and Scatchard plot analysis was used to determine binding coefficients. To assess the influence of hydrophobic core lipid volume on the plasma distribution of CSA, CSA was incubated in plasma from patients with well-characterized dyslipidemias. The hydrophobic core lipid volume (CE + TG) within each lipoprotein subfraction was correlated to the amount of CSA recovered in each plasma sample from the different human subjects. The percent transfer of PC from LDL to HDL was different than the percent transfer of CSA in T150 buffer or human plasma source. In the presence of TP1, only PC transfer from LDL to HDL decreased. For plasma incubated with CSA and separated into HDL(2) and HDL(3), 35-50% of drug originally incubated was recovered in the HDL(3) fraction, with the remaining drug being found within the other fractions. When CSA was incubated in plasma pretreated with DTNB, the percentage of CSA recovered in the HDL(3) and HDL(2) fractions was not significantly different compared with that in the HDL(3) and HDL(2) fractions from untreated control plasma. CSA distribution into HDL inversely correlated with the hydrophobic core lipid volume of HDL, whereas distribution into LDL and triglyceride-rich lipoproteins directly correlated with their respective hydrophobic core lipid volumes. We further observed that CSA has high binding affinity and multiple binding sites with apolipoproteins AI (k(d) = 188.9 nM; n = 2), AII (k(d) = 184.7 nM; n = 2), and B (k(d) = 191 nM; n = 3). These findings suggest that the transfer of CSA between different lipoprotein particles is not influenced by LTP I-facilitated PC transfer activity probably because of the high affinity of CSA for the protein components of HDL and LDL.

Heat-induced superaggregation of amphotericin B modifies its interaction with serum proteins and lipoproteins and stimulation of TNF-alpha.

The purpose of the present study was to examine the influence of heat-induced superaggregation of Amphotericin B (AmB) in the Fungizone (FZ) formulation on its interaction with human serum components and relate this to reduced toxicity. Whole serum distribution studies showed that a significantly lower percentage of AmB from HFZ was recovered in the high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride-rich lipoprotein (TRL) fractions and a greater percentage recovered in the lipoprotein-deficient plasma (LPDP), though the majority of both preparations were recovered in LPDP. Circular dichroism (CD) and difference absorption spectroscopy were used to determine the stability of FZ and heat-treated FZ (HFZ) in the presence of HDL, LDL, serum, and albumin. The CD studies indicate that the "core" aggregate of HFZ is more stable in the presence of HDL and LDL, whereas the FZ is less stable and more dynamic with the core aggregate dissociating to a greater extent in the presence of either purified lipoprotein. Absorption studies with whole serum and purified albumin suggest that FZ aggregates are far less stable in the presence of albumin than HFZ and that interaction with serum albumin is a dominant feature for both drug preparations. HFZ also has a different effect on the cytokine response in vitro. Studies using THP-1 human monocytes show that HFZ provokes a smaller release of tumor necrosis factor (TNF)-alpha than FZ. This cytokine may be associated with the unpleasant side effects of AmB. These findings suggest that heat-induced superaggregation of AmB alters its interaction with HDL, LDL, serum proteins, and monocytes, and these findings may be important in explaining the reduced toxicity of the superaggregated form of AmB.

Determination of procaine in equine plasma and urine by high-performance liquid chromatography.

The variability in plasma and urine equine procaine measurement between three independent laboratories using current methods led to the development of a sensitive, reliable, and reproducible high-performance liquid chromatographic method. Standardbred mares were administered either a penicillin G procaine preparation intramuscularly or procaine hydrochloride subcutaneously, and blood and urine were collected at defined time intervals. By HPLC the detection limits for procaine in plasma and urine were 1 and 10 ng/mL, respectively. In contrast procaine in plasma could not be detected by GC-NPD, while the urinary detection limit was 50 ng/mL. The concentration of fluoride in the collection tubes and repetitive freeze-thawing modified plasma procaine measurement. Urinary pH was a factor in estimation of urine procaine levels with greater recovery and reproducibility of results at pH 5 as compared to pH 7. This HPLC method provides a simple, sensitive, and reliable quantitation of procaine in equine plasma and urine.

Urinary excretion of pentoxifylline and its metabolites by standardbred mares.

The urinary excretion of a sustained-release formulation of pentoxifylline was studied in the horse after the oral administration of 4.0 grams of Trental tablets. Urine samples were collected for 24 hours after dosing and analyzed for pentoxifylline and its metabolites using high-performance liquid chromatography coupled with an ultraviolet detector. Six metabolites of pentoxifylline were identified in horse urine in addition to less than 0.2% of unchanged drug. Concomitant use of gas chromatography/mass spectrometry allowed for the elucidation of the chemical structures of the metabolites. Metabolism of pentoxifylline yields one demethylated derivative, four hydroxylated metabolites and a conjugate of one of the hydroxymetabolites as urine products. The demethylated derivative, 3-methyl-1-(5-oxohexyl)-xanthine, was found to be the predominant metabolite in the urine.