High Power Liquid Chromatography Research Articles

Are 3D printed resin surgical splints safe to use in the mouth? A comparative in vitro study

IntroductionIn orthognathic surgery, surgical splints made of polymethymethacrylate or its variants are used to position the jaws before osteofixation, and occasionally left in-situ for a short duration to guide the occlusion postoperatively. However, allergic reactions can be caused by unreacted dental resin (monomers). Computer aided design/Computer Aided Manufacturing (CADCAM) surgical splints are now more commonly used than the conventionally “handmade” splints. It is unclear if these splints contain uncured residual monomers in any detectable quantity. Materials and methodsCADCAM surgical splints were made from 2 commonly used resins and compared with splints made manually with autopolymerising resin. The splints were immersed in saline at 37°C for 2 weeks to simulate use in the mouth, and the contents were analysed for uncured resin leaching with High Power Liquid Chromatography (HPLC) at different time intervals. ResultsUncured resin content was higher in the conventionally made splint (15,246µg/L on Day 1, 13,539 µg/L on Day 7, and 6,203µg/L on Day 14). One of the CADCAM resins had undetectable monomer quantities, while the other CADCAM resin demonstrated significantly less free monomer compared to the autopolymerising resin (382 µg/L on Day 1, 179 µg/L on Day 7 and 65.2 µg/L on Day 14). ConclusionCADCAM surgical splints have much lower free monomer content compared to the conventionally made splint, and are safe for clinical use.

Spectrum of Haemoglobinopathies in Sikh population of Bangalore: A pilot study

Objectives: To study the burden of different Hemoglobinopathies in the Sikh community of Bangalore. To study their patterns on gel electrophoresis (EPH) and compare the results with hematological parameters and peripheral smear. To confirm the results by cation exchange- High Performance Liquid Chromatography (CE-HPLC) wherever necessary. Materials and Methods: A prospective pilot study was conducted on one hundred and fifty one cases who visited Gurudwara for a regular visit every Sunday. About 2-3 ml. intravenous blood samples were collected after obtaining informed consent from each individual. Background data of each individual were recorded like age, sex, caste, place of origin, consanguinity, etc. Hematological indices were measured using MS4 Cell Counter. Hemoglobin electrophoresis was carried out for the quantification of A2 fraction of hemoglobin by elution method. The use of high performance liquid chromatography is used to separate and quantify abnormal haemoglobin (Hb) fractions that were inseparable on Gel electrophoresis. Results: Most common hemoglobinopathies observed were β?thalassemia trait (5.3%), thalassemia major (0.6%), Hb D trait (1.9%), HbD-β?thalassemia (0.6%), sickle cell trait (0.6%), HbQ disease (0.6%). Conclusions: Proper screening camps and counselling needs to be done on the population at risk about awareness and detection of heterozygous carriers; to prevent the birth of homozygous Beta Thalassemia Major Child. Keywords: Sikh population, Hemoglobinopathies, Electrophoresis, High Power Liquid Chromatography.

Antitumor effect of fibrin glue containing temozolomide against malignant glioma

Temozolomide (TMZ), used to treat glioblastoma and malignant glioma, induces autophagy, apoptosis and senescence in cancer cells. We investigated fibrin glue (FG) as a drug delivery system for the local administration of high-concentration TMZ aimed at preventing glioma recurrence. Our high-power liquid chromatography studies indicated that FG containing TMZ (TMZ-FG) manifested a sustained drug release potential. We prepared a subcutaneous tumor model by injecting groups of mice with three malignant glioma cell lines and examined the antitumor effect of TMZ-FG. We estimated the tumor volume and performed immunostaining and immunoblotting using antibodies to Ki-67, cleaved caspase 3, LC3 and p16. When FG sheets containing TMZ (TMZ-FGS) were inserted beneath the tumors, their growth was significantly suppressed. In mice treated with peroral TMZ plus TMZ-FGS the tumors tended to be smaller than in mice whose tumors were treated with TMZ-FGS or peroral TMZ alone. The TMZ-FGS induced autophagy, apoptosis and senescence in subcutaneous glioma tumor cells. To assess the safety of TMZ-FG for normal brain, we placed it directly on the brain of living mice and stained tissue sections obtained in the acute and chronic phase immunohistochemically. In both phases, TMZ-FG failed to severely damage normal brain tissue. TMZ-FG may represent a safe new drug delivery system with sustained drug release potential to treat malignant glioma.

Comparison of plasma vitamin D levels in patients with Sjögren's syndrome and healthy subjects

Sjögren's syndrome (SS) is a systemic autoimmune disease characterized by chronic inflammation of the salivary and lacrimal glands. There is increasing evidence indicating that vitamin D is important in the initiation and propogation of a range of autoimmune diseases which may include SS. The aim of the present study was to evaluate plasma vitamin D (vit D) levels in patients with SS and to compare this with a control group. One hundred and seven SS patients (97 [90.7%] female and 10 [9.3%] male) and 74 healthy controls (64 [86.5%] female and 10 [13.5%] male) were included into the study. Plasma baseline 25-hydroxy-vit D levels were measured by high-powered liquid chromatography method using an Agilent 1100 liquid chromatograph. Plasma vit D levels in SS patients (20.5±10.5μg/L) were significantly lower than in the control group (28.4±15.2μg/L) (P<0.001). Female SS patients had significanly lower vit D levels (19.3±9.3μg/L) than controls (28.3±15.8μg/L) (P<0.001) but this difference was not present among the male patients and controls. There was no correlation between plasma vit D levels and erythrocyte sedimentation rate and C-reactive protein in SS patients. Vit D deficiency was frequent in patients with SS. In particular, female SS patients had the risk of vit D deficiency. It may be convenient to look for vit D deficiency and to correct vit D nutritional status in SS patients.

An Unusual Cause of Flaccid Paralysis and Coma

Baclofen is a γ-aminobutyric acid (GABA) agonist that is commonly prescribed for the treatment of spasticity in children. The clinical indications for baclofen use in the pediatric population have increased in recent years. Prescribing baclofen mandates education regarding abrupt withdrawal and overdose because of the severe clinical reactions this can precipitate. This report highlights the case of a patient who presented with acute onset of coma and a flaccid paralysis after baclofen overdose. We reviewed the presentation, clinical course, diagnostic studies, and outcome of this patient. A review of prior literature regarding baclofen overdose is included. Baclofen overdose is heralded by dose-related alteration in consciousness and weakness, progressing to coma and a flaccid paralysis. Screening for baclofen overdose is accomplished through high-power liquid chromatography. Baclofen overdose is treated with supportive care and antiepileptic medications as indicated. There is usually full spontaneous recovery with elimination of the medication.

Assessment of Tetracycline, Lead and Cadmium Residues in Frozen Chicken Vended in Lagos and Ibadan, Nigeria

This study determined the levels of tetracycline and heavy metals (lead and cadmium) levels in frozen chicken. One hundred frozen chicken muscle samples were sourced from major markets in Lagos and Ibadan (fifty samples each). The samples were analyzed using high power liquid chromatography (HPLC) for tetracycline residue determination while atomic absorption spectroscopy (AAS) was used to determine the levels of lead and cadmium residues in the samples. Mean concentrations of tetracycline residue levels in the frozen chicken sampled ranged from 1.1589-1.0463ppm which is higher than the maximum residue limit set by international food safety agencies. Pb contents were higher in chicken muscles sampled from markets in Ibadan (0.0227 +/- 0.0069 microg dL(-2)) than Lagos (0.0207 +/- 0.0082 microg dL(-1)), while Cd levels were 0.0013 microg dL(-1) higher than in the Lagos samples (0.0065 +/- 0.0026 microg dL(-1)). These values were within maximum residue limits. There were no significant differences (p < 0.05) in levels of tetracycline, lead and cadmium levels from the two market locations (Lagos and Ibadan) and parts (wings and thigh muscles). However, significant differences occurred in tetracycline and Pb levels in frozen chicken sourced from Cotonou. Though not significant, tetracycline contents in the thigh muscles of the frozen chicken samples was higher than that of the wings muscles and this was attributed to the site of administration of antibiotic injection and failure to observe the pre-slaughter withdrawal period by the farmers. This study is of public health importance as the presence of these residues above the maximum residue limit in frozen chicken predisposes consumers to drug resistance, allergic reactions and poisoning as a result of toxicity.

Anti-inflammatory defense mechanisms of Entamoeba histolytica

The monocyte locomotion inhibitory factor (MLIF), a heat-stable oligopeptide found in the supernatant fluid of Entamoeba histolytica axenic cultures, may contribute to the delayed inflammation observed in amoebic hepatic abscess. This factor was isolated by ultra-filtration and high powered liquid chromatography, obtaining a primary Met-Gln-Cys-Asn-Ser structure, identified afterwards as the carboxyl-terminal (…Cys-Asn-Ser) active site. The selective anti-inflammatory effects of the pentapeptide have been observed in both in vitro and in vivo models, using a synthetic pentapeptide to maintain the same anti-inflammatory conditions during the experimental assays. Anti-inflammatory effects observed include inhibition of human monocyte locomotion and the respiratory burst in monocytes and neutrophils, increasing expression of anti-inflammatory cytokines and inhibiting expression of the adhesion molecules VLA-4 and VCAM, among others. In this review, we will describe the effects of MLIF detected so far and how it might be used as a therapeutical agent against inflammatory diseases.

Detection and quantification of toxins in cultures of microcystis aeruginosa (pcc 7820) by hplc and protein phosphatase inhibition assayffect of blending various collectors at bulk

Increasing anthropogenic eutrophication in lakes, drinking water reservoirs and coastal waters is a world-wide phenomenon leading to the formation of blooms of toxic cyanobacteria. These pose a significant threat to human and animal health hence the need for sensitive methods for their detection, identification and quantification. This report presents two methods: analytical high power liquid chromatography coupled with photo-diode array detection and protein phosphatase inhibition assay for the analysis of the most frequently encountered cyanobacterial hepatotoxins – the microcystins. Four microcystin variants: microcystin - LR, - LY, - LW and - LF were identified and quantified by HPLC in cells and growth media of cultured Microcystis aeruginosa PCC 7820. The protein phosphatase inhibition assay was used to estimate potential toxicity of cyanobacterial extracts and both methods showed good correlation (R2 = 0.91). Although HPLC provides accurateand specific information on the identity and quantity of each microcystin variant, it is quite expensive. The assay method on the other hand is relatively cheaper and can be modified to measure milligrammequantities of sample on a benchtop spectrophotometer but individual microcystin variants cannot be identified

Isolation and characterisation of crocosin, an antibacterial compound from crocodile (Crocodylus siamensis) plasma

An antibacterial compound from crocodile blood was partially purified and functionally characterised. The freshwater crocodile (Crocodylus siamensis) plasma with antibacterial activity was partially purified by using a centrifugal concentrator and reverse phase high powered liquid chromatography, and designated as crocosin. Crocosin exhibits antibacterial activity toward Salmonella typhi and Staphylococcus aureus. Crocosin is thermostable and resistant to pronase digestion. The structure of crocosin analyzed by mass spectrometry contains repeating units of 94 and 136 m/z. Scanning electron microscopy indicates that crocosin probably penetrates progressively into cytoplasm space, perturbing and damaging bacterial membranes. Crocosin may provide an early defense mechanism toward bacterial infection in freshwater.

Aquaporin-2 and -4: Single nucleotide polymorphisms in Ménière's disease patients

AbstractThe endolymphatic hydrops seen in Meniere's disease (MD) results from an inner ear fluid disequilibrium that has a suspected inherited component. Aquaporin-2 and aquaporin-4 (AQP2 and AQP4) water transport proteins may contribute to abnormal fluid homeostasis seen in MD. Our objective was to screen for sequence alterations in AQP2 and AQP4 genes in a northern European population with MD. Amplification for AQP2 (n = 18) and AQP4 (n = 30) was performed for patients with MD. Sequences were screened with denaturing high powered liquid chromatography (DHPLC) and confirmed with sequencing. Allele frequencies were compared with previously reported normal populations. We found that DHPLC failed to identify sequence alterations in any sample. Sequencing identified three intronic and one 3’ untranslated region polymorphism in AQP2, and one polymorphism upstream from the start codon in AQP4. Two of the AQP2 intronic allele frequencies showed an A and C allele enrichment, respectively, compared with a reporte...

Combining Fetal Hemoglobin and Reticulocytosis to Index Clinical Severity of Sickle Cell Disease in Children.

Abstract 2556Poster Board II-533Predictors of disease severity during infancy or childhood in patients with sickle cell disease (SCD) are needed to guide treatment decisions with therapies that have known toxicities [transfusion, hydroxyurea (HU), bone marrow transplant]. Erythrocyte fetal hemoglobin (HbF) expression levels above 20% reduce sickle hemoglobin (HbS) polymerization and decrease hemolysis. As a result of the decreased hemolysis, the survival of erythrocytes is prolonged, and the overall level of erythropoiesis is reduced. To determine if clinical markers of increased HbF production and decreased erythropoiesis may be combined to score disease severity, we developed a Fetal Hemoglobin-Reticulocytosis Index (FRI) defined as: [HbF (%) × non-transfused F-cells (%)] / [Absolute Reticulocyte Count (K/uL)]. For these studies, red cell lysates were analyzed by high power liquid chromatography (HPLC) to estimate HbA, HbS, and HbF fractions. F-cells were analyzed by flow cytometry using antibodies directed against HbF, while transfused cells were labeled with antibodies directed against HbA. Dual staining with both antibodies provided a method for accurately distinguishing transfused and non-transfused F-cells (NT F-cells). A minimum of 10,000 cells was analyzed in all samples. Absolute reticulocyte counts (ARC) were determined using a Sysmex XE 2100 hematology analyzer (Sysmex America, Mundelein, IL). Preliminary studies revealed FRI values near 100 at one month of age followed by a rapid drop before the age of 4 years. Blood from children between the ages of 4 and 21 years was also studied to determine if FRI correlates with therapeutic regimen. FRI values for three groups were compared: those treated with chronic transfusion (n=19, mean FRI=0.72±1.04), HU (n=19, mean FRI=5.61±6.24), versus supportive care alone that did not include recent transfusions (n=42, mean FRI=2.70 ±4.85). When the FRI values from each of these groups were placed in rank order, the slope of the line increased sharply from a linear to an exponential shape near the FRI value of 2. To determine if the FRI=2 inflection may be indicative of reduced disease severity, the number of SCD events were determined in the 42 study subjects treated with supportive care. Overall, twenty-eight (66.7%) patients had an FRI<2, and fourteen (33.3%) patients had an FRI≥2. Among those patients, SCD events were tallied (listed in descending order according to number of events): painful crises requiring hospitalization (FRI<2, n=128; FRI≥2, n=25), pneumonia /acute chest syndrome (FRI<2, n=74; FRI≥2, n=18), splenic sequestration (FRI<2, n=14; FRI≥2, n=0), conditional transcranial Doppler [(TCD), FRI<2, n=13; FRI≥2, n=1), silent stroke (FRI<2, n=4; FRI≥2, n=2), bacteremia (FRI<2, n=2; FRI≥2, n=1), cholecystectomy (FRI<2, n=3; FRI≥2, n=0), and nephropathy (FRI<2, n=1; FRI≥2, n=0). None of the supportive care group had an overt stroke, abnormal TCD, sickle cell retinopathy, or priapism. Age adjusted analysis showed that the FRI≥2 group had significantly fewer total events per year [events/year: FRI<2 (0.70±0.52) vs. FRI≥2 (0.38 ± 0.36), p=0.02]. These data suggest that combining the clinical parameters of fetal hemoglobin production and reticulocytosis provides a simple index for SCD severity. Based upon this retrospective data, prospective studies are underway to determine if the FRI decline during infancy or FRI levels in childhood are useful to predict clinical severity and treatment decisions in SCD patients. Disclosures:No relevant conflicts of interest to declare.

Pharmacology of a novel selective 5-hydroxytryptamine1B receptor antagonist, AR-A000002.

The terminal 5-HT(1B) autoreceptors have attracted great pharmacological interest since they are potential targets for compounds modifying serotonergic neurotransmission. In the present work the in vivo biochemical properties of AR-A000002 ((R)-N-[5-methyl-8-(4-methylpiperazin-1-yl)-1,2,3,4-tetrahydro-2-naphthyl]-4-morpholinobenzamide), a novel selective 5-HT(1B) receptor antagonist, are reported. The effects of AR-A000002 on: 5-HT metabolism was measured as the ratio between 5-HIAA and 5-HT concentrations in different brain regions; 5-HT synthesis was measured as the accumulation of 5-HTP after inhibition of the aromatic amino acid decarboxylase activity with m-hydroxybenzylhydrazine (NSD1015); 5-HT release was measured using the microdialysis technique. 5-HT, 5-HIAA and 5-HTP concentrations were analyzed using high power liquid chromatography (HPLC) with electrochemical detection. AR-A000002 significantly enhanced 5-HT metabolism (5-HIAA/5-HT ratio) and 5-HT synthesis in guinea pig brain in the dose range 0.9-18 mg/kg s.c. (ED(50)=1 mg/kg s.c. in the four brain regions examined) with maximal effect seen after 2-4 h. AR-A000002 (9 mg/kg s.c.) significantly increased the extracellular concentrations of 5-HT and 5-HIAA by 20% in the guinea pig frontal cortex, measured with the in vivo microdialysis technique in freely moving guinea pigs. AR-A000002 (9 mg/kg s.c.) in combination with the 5-HT uptake inhibitor citalopram (5 mg/kg s.c.) increased the extracellular 5-HT concentration in guinea pig frontal cortex from 250 to 400% of the basal level. Citalopram alone decreased the extracellular 5-HIAA levels to 70% of the basal value. AR-A000002 counteracted the citalopram-induced decrease in 5-HIAA. Since the basal level of extracellular 5-HIAA was 160 times higher than that of 5-HT the 20% increase in 5-HIAA concentrations indicates that only a few percent of the exocytotically released 5-HT from the nerve terminals reached the extracellular space when the re-uptake mechanism was intact. The results also show that the terminal 5-HT(1B) autoreceptors are tonically activated under drug-free as well as citalopram conditions. The increase in plasma level of cortisol after AR-A000002 administration may indicate stimulation of post-synaptic 5-HT receptors. AR-A000002 also blocked 5-HT(1B) agonist-induced (CP-135,807) decrease in 5-HT metabolism and hypothermia (ED(50)=1 mg/kg s.c.), thus indicating competition between these two drugs. It is concluded that AR-A000002 is a 5-HT(1B) receptor antagonist that enhances the serotonergic neurotransmission in guinea pig brain.

Myocardial protection with intermittent cold blood during aortic valve operation: antegrade versus retrograde delivery

Background Intermittent antegrade cold blood cardioplegia is superior to warm blood cardioplegia in patients who have aortic valve operation. This study compared the cardioprotective efficacy of intermittent antegrade and retrograde cold blood cardioplegia with emphasis on metabolic stress in the left and right ventricles. Methods Thirty-nine patients who had elective aortic valve replacement were prospectively randomly selected to receive intermittent antegrade or retrograde cold blood cardioplegia. Left and right ventricular biopsies were collected 5 minutes after institution of cardiopulmonary bypass and 20 minutes after cross-clamp removal and were used to determine metabolic changes. Metabolites (adenine nucleotides, amino acids, and lactate) were measured using high-powered liquid chromatography and enzymatic techniques. Serial measurement of troponin I release was also used as a marker of myocardial injury. Results Preoperative characteristics were similar between groups. There was no in-hospital mortality, and no differences were observed in postoperative complications. Preischemic concentration of taurine was significantly higher in left ventricular biopsies, whereas adenosine triphosphate tended to be lower in the left ventricle. At reperfusion adenosine triphosphate levels were significantly lower than preischemic levels in right but not left ventricles irrespective of the route of delivery. The alanine-glutamate ratio was significantly elevated in both ventricles. Myocardial injury as assessed by troponin I release was also significantly increased in both groups. Conclusions Retrograde and antegrade intermittent cold blood cardioplegic techniques are associated with suboptimal myocardial protection. Metabolic stress was more pronounced in the right than the left ventricle irrespective of the cardioplegic route of delivery used.

Erratum to “A fast and efficient determination of amines and preservatives in cough and cold liquid and suspension formulations using a single isocratic ion-pairing high power liquid chromatography method”

Erratum to “A fast and efficient determination of amines and preservatives in cough and cold liquid and suspension formulations using a single isocratic ion-pairing high power liquid chromatography method”

A fast and efficient determination of amines and preservatives in cough and cold liquid and suspension formulations using a single isocratic ion-pairing high power liquid chromatography method

A single, highly selective ion-pairing reverse phase-high power liquid chromatography (RP-HPLC) method has been developed for the determination of amines and preservatives in a wide range of Tylenol((R)) liquid and suspension liquid products. As with many OTC products, the challenge is to quantitatively extract the analytes from difficult matrices and specifically analyze them in the presence of various excipients and flavors. Historically, separate analytical methods were used for each class of analytes (acids, bases and neutral compounds). In this method a mobile phase consisting of a buffered ion-pairing agent with acetonitrile, methanol and tetrahydrofuran was used to separate the charged amines from neutral and acidic compounds on a Phenomenex LUNA C8(2) 75 x 4.6 mm i.d. analytical column with a 3-microm particle size. The analytes include acids (benzoic acid), bases (pseudoephedrine, chlorpheniramine, dextromethorphan, doxylamine and diphenhydramine) and a neutral compound (butylparaben). The effects of pH, the chain length of the ion-pairing reagent, ionic strength and organic modifiers on the separation are discussed. The method is linear from 15 to 150% of the target amounts. The optimized method proves to be specific, robust and accurate for the analysis of the compounds.

A novel anti-inflammatory oligopeptide produced by Entamoeba histolytica

The monocyte locomotion inhibitory factor (MLIF), a heat-stable oligopeptide found in the supernatant fluid of Entamoeba histolytica axenic cultures was isolated by ultra-filtration, gel-sieve chromatography and high powered liquid chromatography (HPLC), and its primary structure (Met-Gln-Cys-Asn-Ser) established by Edman sequencing and mass-spectrometry (MS). A synthetic peptide had the same selective anti-inflammatory features as the native material in comparable concentrations: in vitro inhibition of the locomotion in human peripheral blood monocytes, and of the respiratory burst in the same cells and in human neutrophil polymorphonuclear leucocytes; and in vivo depression of delayed hypersensitivity skin reactions to dinitrochlorobenzene in guinea pigs. This oligopeptide is apparently synthesized by the ameba as suggested by [ 35S]-Cys and Met incorporation, probably as part of a larger molecule, from which it is cleaved by proteolysis. The full sequence was not found in the 431 available E. histolytica protein sequences. The factor may contribute to the unexpected paucity of the late inflammatory reaction found in advanced invasive amebiasis and, perhaps in consequence, to the regeneration without scarring (restitutio ad integrum) of the affected organs that is observed following successful treatment of this disease

Can dietary intake influence plasma levels of amino acids in liver cirrhosis?

Background. Modifications in plasma amino acid patterns in cirrhotics are attributed to impaired liver function, being more evident in alcoholic than in viral cirrhosis. Aim. To evaluate whether diet influences plasma amino acid concentrations in different aetiological groups of cirrhotics. Patients. Study population comprised 40 patients with cirrhosis (25 virus- and 15 alcohol-related), all Child A, and 30 healthy subjects (controls). Method. A food frequency and quality questionnaire was utilized to determine dietary history and alcohol intake. Nutritional status was evaluated by anthropometric method. Amino acids were determined, on venous blood samples, using a specific analyzer, while cysteine was evaluated by fluorescent high power liquid chromatography. Results. The total daily intake of calories, proteins, lipids, and carbohydrates was similar in all individuals. Food quality distinguished the cirrhotics from the controls, but not the different aetiological groups of cirrhotics. Plasma cysteine levels were significantly lower, while aromatic amino acids and methionine were significantly higher, in all cirrhotics (psǑ. 001 and p<O. 01, respectively, versus controls). The decrease in cysteine and the increase in other amino acids were more marked in alcoholics (p<0. 01). Conclusions. Ethanol intake, but not diet, further enhances the changes in plasma aromatic amino acids, methionine and cysteine induced by impaired liver function in patients with cirrhosis, suggesting a direct interference of alcohol in their metabolism.

Costing model for neonatal screening and diagnosis of haemoglobinopathies

AIMTo compare the costs and cost effectiveness of universal and targeted screening for the haemoglobinopathies; to compare the cost of two laboratory methods; and to estimate the cost effectiveness of...

The disposition of intramuscular artemether in children with cerebral malaria; a preliminary study

The disposition of intramuscular artemether (AM) was studied in 26 Kenyan children with cerebral malaria. Antimalarial activity determined by bioassay was compared with total plasma AM plus dihydroartemisinin (DHA) determined by high power liquid chromatography (HPLC). Therapeutic levels were achieved in most subjects ( 21 26 ) within 1 h of receiving intramuscular AM (3·2 mg/kg), with close correlation between bioassay and HPLC measurements ( r = 0·706). However, there was marked inter-individual variation, antimalarial activity was undetectable in 5 subjects (‘non-absorbers’), and plasma concentrations were lower in subjects with respiratory distress. The 50% parasite clearance time was significantly longer in non-absorbers (mean = 13·1 h, sd = 10·8 vs. mean = 7·8 h, sd = 5·5; P = 0·013). We conclude that the bioavailability of intramuscular AM in children with severe malaria may be highly variable, particularly in the presence of respiratory distress, and may be associated with an inadequate therapeutic response.

Screening for neuroblastoma: a 9–year birth cohort–based study in Niigata, Japan

Between April 1985 and March 1994 (9 years), 229,346 babies were born in Niigata prefecture, and 201,888 (88.0%) underwent mass screening (MS) for neuroblastoma at 6 months of age. To date, 29 infants have been screen-detected as having neuroblastoma (1:7908). All screen-detected patients survived after removal of the primary tumor. In the same birth cohort, 17 additional children were clinically diagnosed as having neuroblastoma. The cumulative incidence rate of neuroblastoma at 5 years of age was 10.5 per 100,000 live births in the 5-year birth cohort before MS was introduced, and 18.6 per 100,000 in the first 5-year birth cohort after MS was introduced. These values were not statistically different. The birth cohort incidence rate increased significantly to 22.2 per 100,000 (p < 5% compared with before MS) after the method of MS was changed to high-power liquid chromatography (HPLC), even though this latest birth cohort has not been followed for 5 years. The population-based mortality rate from neuroblastoma was 5.9 per 100,000 in the 5-year birth cohort before MS, and 4.5 per 100,000 after MS in the first 5-year birth cohort, using the vanillymandelic acid (VMA) spot test. These values were not statistically significant. In contrast, no death was observed in the next 4-year birth cohort after MS using HPLC; however, this birth cohort has not yet been followed for 5 years.