Stability of cisplatin and its monohydrated complex in blood, plasma and ultrafiltrate--implications for quantitative analysis

The stability of cisplatin and its monohydrated complex has been studied in blood, plasma and plasma ultrafiltrate at 37 degrees C (pH 7.4). Intact cisplatin and the monohydrated complex were determined by liquid chromatography with post-column derivatization. The half lives for cisplatin and the monohydrated complex were 1.43 +/- 0.03 h (SEM) and 0.36 +/- 0.03 h (SEM), respectively, in blood and 0.88 +/- 0.05 h (SEM) and 0.26 +/- 0.02 h (SEM), respectively, in plasma. The compounds were unstable at -25 degrees C (t1/2 for cisplatin was 52 +/- 5 h (SEM) and for the monohydrated compound 26 +/- 2 h (SEM)), but at -70 degrees C both compounds were stable for at least 3 weeks. The monohydrated complex was found to be formed to a small extent when cisplatin was added to plasma (37 degrees C, pH 7.4). A sampling procedure using centripetal ultrafiltration of whole blood was evaluated and found applicable if the samples were stored at 0 degree C and ultracentrifuged within 1 h.     

Maximum cardiac output during incremental exercise by first-pass radionuclide ventriculography

A flow injection hydride atomic absorption spectrometric (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HNO3 and 0.25 mL H2O2 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140 degrees C (2-3 h). Se (VI) was reduced to Se (IV) with hydrochloric acid. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of argon carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/mL (assay) or 115 pg Se (absolute) in biological samples (1.15 ng/mL milk, 10.4 ng/mL blood). The precision values were 5.0% for milk and 4.0% for blood. The accuracy was evaluated with 2 reference materials, National Institute of Standards and Technology Non-Fat Milk Powder (found: 104.3 +/- 7.2 ng/g, certified: 110 +/- 10 ng/g) and Whole Blood Seronorm (found: 81 +/- 7.3 ng/mL, reference: 83 +/- 4 ng/mL). The results show the suitability of the method for selenium determination in human milk and whole blood. The method was applied to whole blood samples obtained from pregnant women and to human milk.     

Focus on managed care. Organizational structure: sequelae for patients and physicians]

The thermal degradation of plasmid pUC18 held at temperatures between 100 and 135 degrees C was examined by measuring the ability of heat-treated plasmid preparations to transform Escherichia coli to ampicillin resistance using electroporation. Substantial protection against loss of transforming ability during heating was provided by concentrations of NaCl between 0.25 and 2.0 mol l-1. For example, the addition of 1.0 mol l-1 NaCl to samples heated at 100 degrees C for 15 min increased transformation frequency about 200-fold compared with samples heated without NaCl. In the presence of 0.5-2.0 mol l-1 NaCl, transforming capacity was not destroyed even by heating at 121 degrees C for 15 min, i.e. after a typical sterilization treatment. These findings may have implications for the safe disposal of genetically modified micro-organisms and recombinant DNA preparations.     

Beta2-adrenergic agonist residues: simultaneous methyl- and butylboronic derivatization for confirmatory analysis by gas chromatography-mass spectrometry

A derivatization procedure for confirmatory residue analysis of beta2-agonists is described. Methyl (MBA) and butyl (BBA) boronic acids are simultaneously used for the derivatization of tulobuterol, mabuterol, mapenterol, salbutamol, clenproperol, clenbuterol, clenpenterol and bromobuterol by GC-MS determination. A temperature of 55 degrees C during 60 min was selected as optimal temperature-time condition for simultaneous MBA and BBA beta2-agonists derivatization. It was also observed that stability of boronic derivatives was maintained at -20 degrees C over a period of four days. The proposed methodology was tested in urine and it could be applied for confirmatory residue analysis of clenbuterol-like compounds.     

Coexisting mental illness and alcohol and other drug dependencies in pregnant and parenting women

1. To determine whether dexfenfluramine is a substrate of cytochrome P450 2D6 (CYP2D6), its disposition has been studied in nine extensive (EM) and eight poor metabolizers (PM) of debrisoquine. 2. Following a 30 mg dose of dexfenfluramine hydrochloride, urine was collected in all subjects for 96 h post-dose and plasma samples were collected in 11 subjects (six EMs and five PMs). Dexfenfluramine and nordexfenfluramine were measured in urine by h.p.l.c. and in plasma by g.c. 3. Urinary recovery of dexfenfluramine was greater in PMs than EMs (4136 +/- 1509 micrograms vs 1986 +/- 792 micrograms; 95% CI of difference 926-3374; P < 0.05) whereas that of nordexfenfluramine was similar in both phenotypes (PM: 1753 +/- 411 micrograms vs 1626 +/- 444 micrograms). 4. Dexfenfluramine AUC was higher in PMs (677 +/- 348 micrograms l-1 h) than EMs 359 +/- 250 micrograms l-1 h). The apparent oral clearance of dexfenfluramine was greater in EMs than PMs (93.6 +/- 42.4 l h-1 vs 45.6 +/- 19.5 l h-1; 95% CI of difference 1.2-94.7; P < 0.05). The renal clearance was similar in both phenotypes (EMs: 5.88 +/- 2.83 l h-1; PMs 6.60 +/- 2.01 l h-1), indicating that the higher urinary recovery of dexfenfluramine in PMs reflects higher plasma concentrations, rather than phenotype differences in the renal handling, of dexfenfluramine. 5. The apparent nonrenal clearance of dexfenfluramine was substantially lower (P < 0.05; 95% CI of difference 3.0-94.1) in PMs (39.0 +/- 19.5 l h-1) than EMs (87.6 +/- 41.2 l h-1). 6. There was a significant inverse correlation (rs = 0.776 95% CI-0.31-0.94; n = 11; p = 0.005) between the debrisoquine metabolic ratio and the apparent nonrenal clearance of dexfenfluramine. 7. PMs had a higher incidence of adverse effects (nausea and vomiting) than EMs. 8. In conclusion, the metabolism of dexfenfluramine is impaired in PMs. Thus CYP2D6, the isoenzyme deficient in poor metabolizers of debrisoquine, must catalyse at least one pathway of dexfenfluramine biotransformation.     

Methamphetamine-stimulated striatal dopamine release declines rapidly over time following microdialysis probe insertion

A sensitive and selective HPLC method for the determination of ethambutol in human plasma and urine was developed. Ethambutol was extracted from basified plasma samples (0.2 ml) with diethyl ether, back-extracted into 0.01 M phosphoric acid and derivatized with 4-fluoro-7-nitrobenzo-2-oxa-1, 3-diazole. After 30 min at 80 degrees C and elimination of the reactive excess, the compound was determined by reversed-phase liquid chromatography. urine was analysed for ethambutol after dilution 1:200 with distilled water and derivatization as described for plasma. Quantification in plasma and urine was achieved by fluorescence detection of the eluate. The linearity, precision and accuracy of the method were evaluated. No interference from the constituents of human plasma and urine was observed. The limit of quantification was 10 ng/ml in plasma and 10 micrograms/ml in urine. The suitability of the method for in vivo samples was checked by analysis of plasma and urine samples drawn from healthy volunteers who had received a 1200-mg oral dose of the test compound.     

Thermodynamic analysis of human plasma apolipoprotein C-1: high-temperature unfolding and low-temperature oligomer dissociation

Thermal and chemical unfolding of lipid-free apolipoprotein C-1 (apoC-1), a 6-kDa protein component of very low density and high-density lipoproteins, was analyzed by far-UV CD. In neutral 1 mM Na2HPO4 solutions containing 6-7 micrograms/mL protein, the apoC-1 monomer is approximately 30% alpha-helical at 0-22 degrees C and unfolds reversibly from about 22-80 degrees C with Tm = 51 +/- 3 degrees C and van't Hoff enthalpy delta Hv(Tm) = 19 +/- 3 kcal/mol. The apparent free energy of the monomer stabilization determined from the chemical unfolding at 0 degree C, delta G(0 degree C) = 2.8 +/- 0.8 kcal/mol, decreases by about 1 kcal/mol upon heating to 25 degrees C. A small apparent heat capacity increment suggests the absence of a substantial hydrophobic core for the apoC-1 molecule. At pH 7, increasing apoC-1 concentration above 10 micrograms/mL leads to self-association and formation of additional alpha-helices that unfold upon both heating and cooling from room temperature. The CD data indicate that the high-temperature transition reflects a complete monomer unfolding and the low-temperature transition reflects oligomer dissociation into stable monomers. This suggests the importance of hydrophobic interactions for apoC-1 self-association. Close proximity between the high- and low-temperature transitions and the absence of a plateau in the chemical unfolding curves recorded from oligomeric apoC-1 indicate marginal oligomer stability and suggest that in vivo apoC-1 transfer is mediated via the complexes with other apolipoproteins and/or lipids.     

Determination of 2,2,2-trichloroethanol in plasma and urine by ion-exclusion chromatography

A simple and rapid chromatographic method has been developed for the determination of 2,2,2-trichloroethanol (TCEOH) and its glucuronide in plasma and urine. A glass column (150 x 6.6 mm i.d.) packed with Aminex A-5 cation-exchange resin (potassium form) following the slurry method was used as the analytical column, and an admixture of 10 mmol l-1 potassium sulfate and 10 mmol l-1 potassium hydroxide solution as the eluent (pH 12.2). Diluted plasma samples and urine samples were directly injected into the chromatograph through a 0.45 micron membrane filter without deproteinization. The amount of TCEOH conjugated to glucuronide was determined following treatment with beta-glucuronidase (200 U) for 30 min at 37 degrees C. This allowed the concentration of free, total, and conjugated TCEOH to be determined. The calibration graph was rectilinear from 5 to 500 mg l-1 of TCEOH, with a detection limit of 3 mg l-1, 2 sigma, being the signal-to-noise ratio. The analytical recovery of TCEOH, obtained by analysing spiked plasma and urine samples, was in the range 98.4-102% and the relative standard deviation was less than 3.5%.     

Forearm substrate exchange during hyperinsulinaemic hypoglycaemia in normal man

To assess muscle substrate exchange during hypoglycaemia, 8 healthy young male subjects were studied twice during 2 h of hyperinsulinaemic euglycaemia followed by 4 h of (1) hypoglycaemia (plasma glucose < 2.8 mmol l-1), and (2) euglycaemia. Insulin was infused at a rate of 1.5 mU kg-1 min-1 throughout. When compared to euglycaemia, hypoglycaemia was associated with: (1) increment in circulating glucagon (65 +/- 8 vs 23 +/- 4 ng l-1, p < 0.05), growth hormone (19.9 +/- 3.6 vs 2.6 +/- 1.3 micrograms l-1, p < 0.05), adrenaline (410 +/- 88 vs 126 +/- 32 ng l-1, p < 0.05) and increased suppression of C-peptide (0.5 +/- 0.1 vs 1.0 +/- 0.1 micrograms l-1, p < 0.05) along with a modest lowering of insulin (103 +/- 10 vs 130 +/- 13 mU l-1, p < 0.05); (b) decrease in plasma glucose level (3.0 +/- 0.07 vs 5.0 +/- 0.12 mmol l-1, p < 0.05), forearm glucose uptake (0.21 +/- 0.09 vs 1.21 +/- 0.21 mmol l-1, p < 0.05) and requirement for exogenous glucose (5.6 +/- 1.1 vs 13.2 +/- 0.9 mg kg-1 min-1 p < 0.005) together with an impaired suppression of isotopically determined endogenous glucose production (0.34 +/- 0.5 vs -2.3 +/- 0.3 mg kg-1 min-1, p < 0.05); (3) exaggerated increase in blood lactate (1680 +/- 171 vs 1315 +/- 108 mumol l-1, p < 0.05) and a decrease in alanine (215 +/- 18 vs 262 +/- 19 mumol l-1, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ambient temperature effects on thermoregulation and endurance in anticholinesterase-treated rats

In sedentary animals, physostigmine (PH) administration resulted in a decreased core temperature that is ambient temperature (Ta) dependent. PH administration in rats exercising on a treadmill (26 degrees C, 50% rh, 11m/min, 6 degrees incline) decremented endurance and increased rate of rise of core temperature (heating rate, HR). This study was undertaken to examine the effects of Ta on the endurance and thermoregulatory decrements of PH-treated running rats. Adult male rats (510-530g) were given either 0.2ml saline (C) or 100 ug/kg physostigmine salicylate in 0.2 ml saline via tail vein 15 min prior to the start of running to exhaustion at 10, 15, 26, or 30 degrees C. In both C- and PH-treated groups, endurance decreased and HR increased with increasing Ta from 15 to 30 degrees C. At 15 and 26 degrees C the C rats ran significantly (p < .05) longer and had significantly lower HR than the PH rats: C15 = 90 +/- 8 min, 0.022 +/- 0.006 degrees C/min; C26 = 67 +/- 6, 0.051 +/- 0.007; PH15 = 57 +/- 5, 0.052 +/- 0.008; and PH26 = 43 +/- 6, 0.092 +/- 0.007. At 10 and 30 degrees C there were no significant differences between C and PH-treated rats. A Ta of 30 degrees C was too high for effective cooling in either group, and at 10 degrees C both groups were able to dissipate heat despite the increased metabolic rate of the PH-treated rats. The PH-treated rat model of cholinergic drug effect is useful at a Ta of 15 and 26 degrees C.     

Renal hemodynamics during norepinephrine and low-dose dopamine infusions in man

OBJECTIVE: To characterize the effects of pressor doses of norepinephrine and low-dose dopamine (3 micrograms/kg/min) on renal hemodynamics in man, as well as to determine the clinical relevance of combining dopamine with norepinephrine. DESIGN: Prospective, single-blind, randomized study. SETTING: Clinical research unit of a tertiary care hospital. SUBJECTS. Six healthy male volunteers ranging in age between 20 and 28 yrs. INTERVENTIONS: The subjects were assigned randomly to four treatments (1 wk apart) in which renal hemodynamics and electrolyte excretion were assessed. Treatments consisted of 180-min infusions of the following: a) 0.9% sodium chloride (control); b) pressor doses of norepinephrine; c) dopamine at 3 micrograms/kg/min; and d) pressor doses of norepinephrine and dopamine at 3 micrograms/kg/min. Pressor doses of norepinephrine was defined as doses required to increase mean arterial pressure (MAP) by 20 mm Hg. MEASUREMENTS AND MAIN RESULTS: Glomerular filtration rate and renal blood flow were derived from inulin and para-aminohippurate clearances, respectively. Urine output and urine solute excretion were also determined. The mean norepinephrine dose required to increase MAP by 22 +/- 2 mm Hg was 118 +/- 30 ng/kg/min (range 76 to 164). After the addition of dopamine, similar doses of norepinephrine resulted in an MAP increase of 15 +/- 4 mm Hg. Glomerular filtration rate and urine output were comparable under all conditions. The infusion of norepinephrine decreased renal blood flow from 1241 +/- 208 to 922 +/- 143 mL/min/1.73 m2 (p = .03). The addition of dopamine returned renal blood flow to baseline values. The clearance of urine sodium increased significantly with the infusion of dopamine alone (p = .03). All subjects completed the four treatment periods. Adverse events, manifested mostly as palpitations and flushing, were rare and self-limiting. CONCLUSIONS: The addition of dopamine (3 micrograms/kg/min) to pressor doses of norepinephrine normalized renal blood flow in healthy volunteers. These hemodynamic changes were not reflected in urine output and glomerular filtration rate; hence, these monitoring parameters may be unreliable indicators of renal function in the setting of vasopressor therapy. In addition, systemic effects were observed with dopamine (3 micrograms/kg/min), as indicated by a decrease in MAP.     

Fenoldopam improves renal hemodynamics impaired by positive end-expiratory pressure

BACKGROUND: Mechanical ventilation with positive end-expiratory pressure (PEEP) can impair renal hemodynamics. Fenoldopam, a dopamine receptor agonist, has been shown, in animal experiments, to improve renal perfusion. The purpose of the current study was to examine the effects of this agent on altered renal hemodynamics secondary to positive pressure ventilation. METHODS: Twelve patients requiring mechanical ventilation of their lungs and PEEP for the treatment of hypoxemia after multiple trauma or visceral surgery were studied. Hemodynamic variables, renal vascular resistance, urine flow, creatinine, inulin and PAH clearance, and excretion of sodium and potassium (NaE and KE) were measured before and after introduction of a level of PEEP high enough to decrease urine flow rate by 25% or more, and after administration of intravenous fenoldopam. RESULTS: No hemodynamic effect resulted from 0.1 microgram.kg-1.min-1, but 0.2 micrograms.kg-1.min-1 fenoldopam decreased both diastolic and mean arterial blood pressure from 66 +/- 37 (mean +/- SEM) to 57 +/- 21 mmHg, and from 83 +/- 3 to 74 +/- 4 mmHg, respectively. Renal vascular resistance was reduced from 54 +/- 12 to 19 +/- 5 dynes.s.cm-5 at 0.2 micrograms.kg-1.min-1. Fenoldopam produced a dose-related increase in renal blood flow and PAH clearance. With 0.2 micrograms.kg-1.min-1 fenoldopam, urine flow increased from 81 +/- 25 to 116 +/- 29 ml/h, NaE from 28 +/- 7 to 85 +/- 70 microM/min, and KE from 65 +/- 12 to 109 +/- 16 microM/min. CONCLUSIONS: The results of the current study indicate that intravenous fenoldopam at a dose of 0.2 micrograms.kg-1.min-1 improves renal hemodynamics and increases Na and K excretion in patients requiring mechanical ventilation of their lungs and PEEP. These effects are probably caused by an increased kidney perfusion secondary to renal artery vasodilation.     

Protein phylogeny of translation elongation factor EF-1 alpha suggests microsporidians are extremely ancient eukaryotes

trans, trans-Muconic acid (1,3-butadiene-1, 4-dicarboxylic acid, MA), a minor urinary metabolite of benzene exposure, was determined, after clean-up by solid-phase anion-exchange chromatography, by reversed-phase HPLC on a C18 column (5 x 0.46 cm I.D., 3 microns particle size), using formic acid-tetrahydrofuran-water (14:17:969) as mobile phase and UV detection at 263 nm. The recovery of MA from spiked urine was > 95% in the 50-500 microgram/l range; the quantification limit was 6 micrograms/l; day-to-day precision, at 300 micrograms/l, was C.V. = 9.2%; the run time was less than 10 min. Urinary MA excretion was measured in two spot urine samples of 131 benzene environmentally exposed subjects: midday values obtained in non-smokers (mean +/- S.D. = 77 +/- 54 micrograms/l, n = 82) were statistically different from those of smokers (169 +/- 85 micrograms/l, n = 30) (P < 0.0001); each group showed a statistically significant increase between MA excretion in midday over morning samples. Moreover, in subjects grouped according to tobacco-smoke exposure level, median values of MA were positively associated with and increased with daily smoking habits.     

Profile of the DNA recognition site of the archaeal homing endonuclease I-DmoI

1. Long-term treatment with beta 2-adrenoceptor agonists can lead to a decreased therapeutic efficacy of bronchodilatation in patients with obstructive pulmonary disease. In order to examine whether or not this is due to beta-adrenoceptor desensitization, human bronchial muscle relaxation was studied in isolated bronchial rings after pretreatment with beta 2-adrenoceptor agonists. Additionally, the influence of pretreatment with dexamethasone on desensitization was studied. 2. The effect of beta 2-agonist incubation alone and after coincubation with dexamethasone on density and affinity of beta-adrenoceptors was investigated by radioligand binding experiments. 3. In human isolated bronchi, isoprenaline induces a time- and concentration-dependent beta-adrenoceptor desensitization as judged from maximal reduction in potency by a factor of 7 and reduction of 73 +/- 4% in efficacy of isoprenaline to relax human bronchial smooth muscle. 4. After an incubation period of 60 min with 100 mumol l-1 terbutaline, a significant decline in its relaxing efficacy (81 +/- 8%) and potency (by a factor 5.5) occurred. 5. Incubation with 30 mumol l-1 isoprenaline for 60 min did not impair the maximal effect of a subsequent aminophylline response but led to an increase in potency (factor 4.4). 6. Coincubation of dexamethasone with isoprenaline (120 min; 30 mumol l-1) preserved the effect of isoprenaline on relaxation (129 +/- 15%). 7. In radioligand binding experiments, pretreatment of lung tissue for 60 min with isoprenaline (30 mumol l-1) resulted in a decrease in beta-adrenoceptor binding sites (Bmax) to 64 +/- 1.6% (P < 0.05), while the antagonist affinity (KD) for [3H]-CGP-12177 remained unchanged. 8. In contrast, radioligand binding studies on lung tissue pretreated with either dexamethasone (30 mumol l-1) or isoprenaline (30 mumol l-1) plus dexamethasone (30 mumol l-1) for 120 min did not lead to a significant change of Bmax (160 +/- 22.1% vs 142.3 +/- 28.7%) or KD (5.0 nmol l-1 vs 3.5 nmol l-1) compared to the controls. 9. In conclusion, pretreatment of human bronchi with beta-adrenoceptor agonists leads to functional desensitization and, in lung tissue, to down-regulation of beta-adrenoceptors. This effect can be counteracted by additional administration of dexamethasone. Our model of desensitization has proved useful for the identification of mechanisms of beta-adrenoceptor desensitization and could be relevant for the evaluation of therapeutic strategies to counteract undesirable effects of long-term beta-adrenoceptor stimulation.     

Reproducibility of the vascular response to heating in human skin

Blood flow in human skin increases enormously in response to direct heating. If local skin temperature is held above 42 degrees C, blood flow eventually stabilizes at a level beyond which other influences, barring change in blood pressure, can produce no further increase. If this maximal level is a reproducible characteristic of an individual's cutaneous vasculature, it could be useful in comparing individuals; for example, in their response to hyperthermia. Our experiments were carried out to discover whether the maximal response of the vasculature of the skin of the forearm can be reproduced within reasonable limits and, also, to clarify the time course of the response. We used water sprayed over the surface of the forearms of 10 subjects to hold skin temperature above 42 degrees C for 60 min. During the last 10 min of heating, forearm blood flow (via venous occlusion plethysmography) was stable, at a level ranging from 16 to 38 ml.min-1.100 ml-1. This level, normalized to a blood pressure of 100 mmHg, was reproduced in a given individual on four or five occasions, with an average coefficient of variation of 10%. The response was 77 +/- 11% (SD) complete after 20 min of heating. Elapsed time at 90% of the final value was 35 +/- 9 (SD) min. We conclude that the maximal forearm blood flow response to local heating is a reproducible characteristic of the cutaneous vasculature with potential utility in the scaling of responses between and within individuals.     

Cyanide determination in biological fluids using a microdiffusion method with a flow system and polarographic detection

The report describes a method for the automated polarographic determination of cyanide as tetracyanonickelate (II) anion complex in a gas-diffusion flow system. The volatile cyanide, existing in whole blood, plasma and urine samples, was measured after gas-diffusion using 8 x 10-5 mol l-1 hexaaminenickel solution as acceptor. The linear range of calibration, for measurements at the hanging mercury-drop electrode (HMDE), was from 0.1 to 2.0 micrograms cyanide with r = 0.998. The RSD was, respectively, 3.4 and 1.2% (n = 5) for 0.4 microgram cyanide measured with and without the flow-system configuration. Detection limits of 7.4 microgram l-1 were calculated using the flow system and the method was compared with the classical method using Cavet flasks. Parameters that affect the cyanide determination in the proposed method, such as acceptor solution, pH, flow rate and temperature, were investigated.     

Bismuth concentration in blood and urine of children treated with ventrisol (polfa) preliminary study

The bismuth concentration was measured in the blood and urine of 21 children from 8 to 17 years old (13.12 +/- 2.67) treated with Ventrisol (Polfa)-tripotassium dicitrato bismuthate (TDB). One tablet of TDB-equivalent to 120 mg Bi2O3. One tablet was given orally to the patients four times a day. Blood and urine was taken for measurement of bismuth concentration in the morning, on fasting, before the administration of Ventrisol on the 6-8 days, the 27-28 days of the therapy and in the 4-5, 8-9 weeks after TDB therapy. The reason for TDB treatment was chronic gastritis and/or duodenal ulcers, which were diagnosed by endoscopic examination. No bismuth in the blood and a very low concentration in the urine were determined in 19 children before TDB treatment. After 6-8 days of TDB treatment the bismuth concentration in the blood was 40.85 +/- 31.05 micrograms/L and 75.11 +/- 82.07 micrograms/L in the urine. In the 27-28 days of the treatment the bismuth concentration in the blood was 37.67 +/- 25.06 micrograms/L, and 163.56 +/- 181.86 micrograms/L in the urine. In the 4-5 weeks after the TDB treatment the bismuth concentration in the blood was 7.77 +/- 10.56 micrograms/L, and 15.72 +/- 9.87 micrograms/L in the urine. The bismuth concentration level in the urine rose together with the rise of the bismuth concentration level in the blood, the correlation factor was r = 0.68. No symptoms of side effects caused by the TDB treatment were observed. Before the treatment a high bismuth concentration was found in the blood of two patients. These cases are discussed later.     

Physiological and histological characterisation of a pig kidney in vitro perfusion model for xenotransplantation studies

A pig kidney perfusion model aimed for use in immunological and physiological xenotransplantation research has been developed. Organ viability was characterised by clearance studies, functional response to hormones/diureticum and by light microscopical examination. The pig kidney was perfused in a specially designed plexiglass chamber, using a roller pump and a small membrane oxygenator (O2/CO2, 95/5). The recirculating perfusate used was autologous pig blood diluted by Tyrodes solution to a hematocrit of 30%, at a total starting volume of 600-650 ml. The temperature was 37 degrees C. It was crucial for good organ function that the nephrectomy operating time, as well as the warm (1-2 min) and cold ischemia (average 43 min) times were minimized. The average total perfusion time was 151 minutes. Physiological parameters were measured during 10-15 minute periods at average times of 40, 63, 88 and 142 minutes. The clearance values of inulin in these periods were 54 +/- 13, 59 +/- 15, 48 +/- 23, 27 +/- 5 and for PAH; 103 +/- 14, 121 +/- 14, 106 +/- 30, 114 +/- 34 ml/min/100 g tissue weight. The plasma flows were 123 +/- 12, 155 +/- 17, 136 +/- 36 and 206 +/- 57 ml/min/100 g. The injection of 0.5 micrograms of alpha ANP to the perfusate resulted in a significant decrease in vascular resistance, and increase in urine production (+107%), as well as sodium (+112%) and potassium (+46%) excretion. Ten mg furosemide doubled the urine production and sodium excretion, while potassium excretion increased marginally. The number of leucocytes decreased by 39% during the perfusion, while the platelet count was unaffected. Light microscopy of the renal tissue after termination of the experiments revealed endothelial damage to variable extent. Loss of endothelial cells was most obvious at the level of arcuate and interlobular arteries, while the endothelium was intact in larger arteries and veins. Accumulation of polymorphonuclear granulocytes was found predominantly in the peritubular vessels, and to a lesser degree in the cortical venules. In the tubular cells, only minimal epithelial swelling and irregular cytoplasmic vacuolisation was found. Thus, a good functional viability can be maintained during 2 hours in vitro perfusion, although a decline in function as well as structural damage can be seen at the end of the experiment.     

Direct determination of selenium in human blood serum and plasma by electrothermal atomic absorption spectrometry

A method is described for the direct determination of selenium in serum or plasma by electrothermal atomic absorption spectrometry with deuterium-arc background correction. Samples are diluted (1 + 2) with a modifier containing palladium nitrate and Triton X-100. Samples are atomised from a L'vov platform in a pyrolytically-coated electrographite tube and peak area signals are measured. Direct determination is possible by using selenium standards matched to the physiological concentrations of sodium chloride, calcium and phosphate. The detection limit is 6 micrograms/L in the original sample. Precision at a selenium concentration of 97 micrograms/L was 2.2% RSD within batch and 3.0% RSD between batch. Accuracy is shown by (i) analysis of a Seronorm reference serum (value obtained 97 +/- 3 micrograms/L; recommended value 96 micrograms/L); (ii) recovery of added selenium (93.3 +/- 6.7% and 98.2 +/- 3.3% at additions of 30 and 60 micrograms/L, respectively) and (iii) comparison of results with mean of all laboratories in an external quality assessment scheme.     

The effect of dry heat on mite, cat, and dog allergens

BACKGROUND: Various techniques have been tried in an attempt to reduce allergen levels in homes. This study investigated the effect of dry heat on mite, cat, and dog allergens. METHODS: Samples (50 mg) of Dermatophagoides pteronyssinus and D. farinae cultures, and of house dust rich in the major cat and dog allergens Fel d 1 and Can f 1 were heated for 5, 10, 15, 30, and 60 min at 60 degrees, 80 degrees, 100 degrees, 120 degrees, and 140 degrees C. Control samples remained at room temperature. Extracts were assayed with the appropriate two-site mono- or mono/polyclonal sandwich ELISA. RESULTS: For Der p 1, the breakdown was proportional to temperature and heating time; after 30 min at 120 degrees C, allergen levels were reduced to < 1% of control. Der p 2 was more heat stable, requiring 140 degrees C for 30-60 min to achieve > 99% reduction. D. farinae groups 1 and 2 allergens showed results similar to those obtained with D. pteronyssinus. In contrast, Can f 1 and Fel d 1 were considerably more thermostable, with 50% and 70%, respectively, of allergen remaining after 60 min at 140 degrees C. CONCLUSIONS: The effect of dry heat on allergens increased with increasing time and temperature, cat and dog allergens demonstrating greater heat resistance than mite allergens. Dry heating methods may represent an alternative technique for removal of mite allergens; however, the greater stability of Fel d 1 and Can f 1 suggests that this procedure may not be appropriate for pet allergens.