Biomedical subjects

D A Anderson

Publications and source records attributed to D A Anderson.

At least 37 records · Page 2Linked to original sources

PubMed1999

Serological evidence for swine hepatitis E virus infection in Australian pig herds.

Hepatitis E virus (HEV) is an enterically transmitted human pathogen, with some similarities to caliciviruses. A variant of HEV was recently identified in pigs in the USA, infecting almost 100% of animals in commercial herds. Phylogenetic analysis suggests that this is a true 'swine HEV' distinct from the human virus, but the swine virus may also infect man. Using an in-house ELISA based on a highly conserved, recombinant HEV protein, we have examined collections of sera from Australian pigs for evidence of HEV infection in local pig herds. Sera from one research herd (n = 32) were uniformly non-reactive, and this was used to establish an assay cut-off (= mean + 3 SD of reference pig serum reactivities). Screening of sera from other herds demonstrates that swine HEV is present in Australia, with reactivity observed in 30% (12/40) of random samples from two piggeries, 92-95% of pigs by the age of 16 weeks in two other piggeries (n = 45), and 17% (15/59) of wild-caught pigs. Further studies are required to examine whether HEV causes disease in pigs and to determine the risk of swine HEV transmission to man.

Age Factors↗

PubMed1999

Seroprevalence of antibodies to hepatitis E virus in the normal blood donor population and two aboriginal communities in Malaysia.

The prevalence of antibodies to hepatitis E virus (HEV) has been examined in many countries, but such studies have generally been limited to majority populations such as those represented in healthy blood donors or cross sections of urban populations. Due to its major route of enteric transmission, large differences in HEV prevalence might be expected between populations in the same country but with different living conditions. Using an ELISA based on GST-ORF2.1 antigen, the prevalence of IgG-class antibodies to HEV was examined in three distinct populations in Malaysia: the normal (urban) blood donor population and two aboriginal communities located at Betau, Pahang and Parit Tanjung, Perak. IgG anti-HEV was detected in 45 (44%) of 102 samples from Betau and 15 (50%) of 30 samples from Parit Tanjung, compared to only 2 (2%) of 100 normal blood donors. The distribution of sample ELISA reactivities was also consistent with ongoing sporadic infection in the aboriginal communities, while there was no significant relationship between HEV exposure and age, sex, or malaria infection. The high prevalence of antibodies to HEV in the two aboriginal communities indicates that this group of people are at high risk of exposure to HEV compared to the general blood donors, and the results suggest that studies of HEV seroprevalence within countries must take into account the possibility of widely varying infection rates between populations with marked differences in living conditions.

Adolescent↗

PubMed1999

Two-year changes in lipids and lipoproteins associated with the maintenance of a 5% to 10% reduction in initial weight: some findings and some questions.

OBJECTIVE: This study assessed whether a 5% to 10% reduction in initial weight would be associated with as favorable long-term (i.e., 100 weeks) changes in lipids and lipoproteins, as have been observed on a short-term basis (i.e., 8 weeks). RESEARCH METHODS AND PROCEDURES: This was a prospective evaluation of 25 obese women, each of whom had lost > or =5% of initial weight during 48 weeks of treatment and had maintained a weight loss of this magnitude at 1-year follow-up (week 100). Lipids and lipoproteins were obtained at baseline and at weeks 8, 24, 48, and 100. All participants had a baseline total cholesterol > or =5.17 mmol/L (200 mg/dL). RESULTS: At the end of the first 8 weeks, weight fell an average of 11.7+/-2.8%, total cholesterol 20.6+/-7.5%, low-density-lipoprotein (LDL) cholesterol 23.0+/-18.1%, and triglycerides 26.0+/-20.1%. At week 48, weight had fallen to 20.1+/-7.0% below baseline, but total cholesterol and LDL cholesterol were reduced only 11.5+/-10.4% and 12.0+/-14.0% below baseline, respectively. These latter reductions were significantly (p<0.05) smaller than those observed at week 8, despite the larger weight loss at week 48. High-density-lipoprotein cholesterol declined significantly (p<0.05) during the first 8 weeks, but returned to baseline values by week 24. Patients gained 7.4+/-7.4 kg from weeks 48 to 100, during which time total and LDL cholesterol (but not triglycerides) rose significantly (p<0.05). Patients who, at week 100, maintained losses >10% of initial weight had significantly greater reductions in total and LDL cholesterol values than did patients who maintained losses of only 5% to 10% of initial weight. DISCUSSION: Results of this study underscore the importance of assessing long-term changes in weight-related health complications when patients have lost weight but are no longer dieting (and exercising) as aggressively as they did during the initial months of treatment.

Adult↗

PubMed1999

Estimation of food intake: effects of the unit of estimation.

While many studies have shown that individuals under-estimate caloric intake, few studies have examined how individuals estimate intake when using other units of measurement (e.g. cups, ounces). Forty-one women (21 obese, 20 normal weight) ate a test meal of Häagen-Dazs chocolate ice cream and were asked to estimate the amount they ate in both calories and cups. As expected, participants under-estimated intake when asked to estimate how much they ate in calories, but considerably over-estimated their intake when measured in cups. Thus, individuals can both under- and over-estimate how much of the same food they have eaten, depending on the unit they are asked to use for estimation. Obesity and eating disorders treatment programs should take into account the tendency to over-estimate volumetric portions as well as under-estimate caloric intake.

Adult↗

PubMed1999

ELISA for IgG-class antibody to hepatitis E virus based on a highly conserved, conformational epitope expressed in Escherichia coli.

In assays based on most recombinant hepatitis E virus (HEV) antigens, the IgG antibody responses to HEV are observed commonly to wane or disappear after the acute phase of infection. Such IgG assays have therefore been used for the diagnosis of acute HEV infection, but they have limited usefulness in seroepidemiological studies. Using western immunoblotting, it was shown previously that the open reading frame (ORF) 2.1 antigen, representing the carboxy-terminal 267 amino acids (aa) of the capsid protein, exposes a conformational epitope which allows optimal detection of convalescent antibody compared to other proteins expressed in Escherichia coli. This conformational epitope is shown to be highly conserved between divergent human HEV isolates, and the development of a sensitive and highly specific enzyme immunoassay (ELISA) based on this recombinant antigen is described. The ORF2.1 ELISA allows the detection and quantitation of both acute- and convalescent phase HEV-specific IgG, and will help to define better the antibody responses to the virus and the prevalence of HEV infection worldwide.

Animals↗

PubMed1999

Changes in resting energy expenditure after weight loss in obese African American and white women.

BACKGROUND: Previous studies showed that resting energy expenditure (REE) is lower in obese African American women than in obese white women. It is unknown, however, whether there are racial differences in how REE responds to weight loss and energy restriction. OBJECTIVE: We assessed REE, body composition, and respiratory quotient before and after weight loss in obese black and white women. DESIGN: We measured REE by indirect calorimetry and body composition by densitometry before and after 20-24 wk of treatment with a 3870-4289-kJ/d diet. Subjects were 109 obese females (24 black, 85 white) with a mean (+/-SD) body mass index (in kg/m2) of 36.3+/-5.0, weight of 95.7+/-12.6 kg, and age of 42.3+/-8.1 y. RESULTS: Before treatment, REE, adjusted for body composition, was significantly lower in black than in white subjects (P = 0.001). Black subjects lost significantly less weight during treatment than did white subjects (13.4+/-5.9 kg or 14.2+/-5.7% compared with 16.4+/-5.6 kg or 17.0+/-5.7%, respectively; P = 0.04). Analyses that controlled for initial REE and changes in fat mass and fat-free mass showed that blacks had significantly greater decreases in REE after treatment than did whites (9.9+/-7.3% compared with 6.3+/-7.4%; P = 0.02). CONCLUSION: This study suggests that weight loss results in greater reductions in REE in obese black women than in obese white women. These data underscore the need to consider both biological and behavioral factors when setting expectations and assessing outcomes for obesity treatment in African American women.

Adult↗

PubMed1999

Only the non-glycosylated fraction of hepatitis E virus capsid (open reading frame 2) protein is stable in mammalian cells.

Hepatitis E virus (HEV) is a non-enveloped, positive-strand RNA virus, with the genome encoding three open reading frames (ORFs) of which ORF 2 directs translation of the capsid protein, PORF2. Following pulse-labelling and cell fractionation of PORF2 expressed in mammalian cells using the Semliki Forest virus replicon, the capsid protein was detected as three major species of 78 (PORF2), 82 and 86 kDa, with P82 and P86 being N-glycosylated (gPORF2 and ggPORF2, respectively). Although gPORF2 and ggPORF2 species represented 79% of total PORF2 after 20 min metabolic labelling and were largely membrane-associated, the glycosylated PORF2 species were much less stable than non-glycosylated PORF2, which was present in the cytosol and represented the major product accumulated in the cell. In the absence of detectable surface expression or export of PORF2, this suggests that glycosylated ORF 2 proteins may not be intermediates in HEV capsid assembly.

Animals↗

PubMed1999

Development and validation of a multifactorial treatment outcome measure for eating disorders.

The purpose of this investigation was to develop a brief self-report inventory which could be used to evaluate treatment outcome for anorexia and bulimia nervosa. The Multifactorial Assessment of Eating Disorders Symptoms (MAEDS) was constructed to measure six symptom clusters which have been found to be central to the eating disorders: depression, binge eating, purgative behavior, fear of fatness, restrictive eating, and avoidance of forbidden foods. The factor structure of the MAEDS was found to be stable and it was found to have satisfactory reliability and validity. Normative data were collected so that raw scores could be converted to standardized scores. While still in the experimental stages, the MAEDS shows promise as a valid and economical measure of treatment interventions for anorexia and bulimia nervosa.

Adolescent↗

PubMed1999

Web sites for midwives.

With increasingly more useful information becoming available on the World Wide Web and with the Internet becoming accessible to everyone, an organized and annotated review of sites beneficial to midwives is an important tool. In addition to being useful to midwifery professionals, this listing will be helpful to nursing and midwifery educators and students, to pregnant women and their families, and to the reference librarian providing assistance to these individuals. This article provides individuals interested in midwifery with the ability to choose from evaluated Web sites.

Female↗

PubMed1998

Intracellular retention of duck hepatitis B virus large surface protein is independent of preS topology.

The mechanism of intracellular retention for the large surface protein (L) of duck hepatitis B virus (DHBV) was analyzed by examination of the transmembrane topologies and secretory properties of a collection of DHBV L mutants and compared with that of human hepatitis B virus (HBV) L. Our results demonstrate that, in contrast to its HBV counterpart, intracellular retention of DHBV L does not depend on the cytosolic disposition of its preS domain. L mutants with either cytosolic or lumenal preS were mostly retained in the absence of the small surface protein (S), whereas coexpression with S resulted in efficient secretion of both topological forms. Coexpression of the wild-type DHBV L with S resulted in efficient incorporation of L into secreted S + L particles, whereas HBV L was partially excluded from secreted particles under the same conditions. We propose that HBV provides L retention even in the presence of an excess of S, by exclusion of molecules with cytosolic preS domains from secreted particles at the stage of their assembly. DHBV lacks such a retention mechanism due to the absence of topological selection in particulate assembly.

Animals↗

PubMed1998

Exercise and the maintenance of weight loss: 1-year follow-up of a controlled clinical trial.

This study reports results 1 year after treatment for 77 obese women who had been treated for 48 weeks by diet combined with supervised (a) aerobic exercise, (b) strength training, (c) aerobic plus strength training combined, or (d) no exercise. Mean (+/- SD) end-of-treatment weight losses for the 4 conditions ranged from 13.5 +/- 9.1 kg to 17.3 +/- 10.3 kg, but there were no statistically significant differences among groups. Participants in all 4 conditions regained approximately 35% to 55% of their weight loss in the year after treatment; again, there were no significant differences among groups. Participants, however, who reported exercising regularly in the 4 months preceding the follow-up assessment regained significantly less weight than did nonexercisers.

Adult↗

PubMed1998

Normal phosphorylation of duck hepatitis B virus L protein is dispensable for infectivity.

A fraction of the large surface protein (L) of duck hepatitis B virus (DHBV) is phosphorylated at serine or threonine residues (E. Grgacic & D. Anderson, Journal of Virology 68, 7344-7350, 1994). We now report the identification of phosphorylation sites in DHBV L protein. Using site-directed mutagenesis, we have identified serine-118 (S118) as the major phosphorylation site, accepting approximately 64% of the total phosphate groups incorporated in L, and resulting in retarded migration of phosphorylated L in SDS-PAGE. Proline-119 is indispensable for S118 phosphorylation. Mutation of other serine/threonine residues which are followed by prolines (T79, T89, S117 and T155) together with S118 further reduced phosphorylation to around 19% of wild-type. Non-equilibrium pH gel electrophoresis (NEPHGE) and SDS-PAGE of 33P-labelled L protein revealed two phosphorylated L species, while protein with the S118 to alanine mutation was detected as only one labelled species, consistent with multiple phosphorylations in wild-type L. Together, these results demonstrate that serine 118 is the major phosphorylation site for a proline-directed kinase, and that a proportion of L molecules are additionally phosphorylated at one of a number of secondary sites. DHBV mutants encoding L proteins with minimal phosphorylation (alanine mutants) or mimicking constitutive phosphorylation (aspartic acid mutants) remained infectious both in cell culture and in ducks, demonstrating that L phosphorylation may play only a minor role in DHBV replication.

Animals↗

PubMed1998

Short- and long-term changes in serum leptin dieting obese women: effects of caloric restriction and weight loss.

This study examined the effects of caloric restriction and weight loss on serum leptin concentrations in 49 obese women who participated in a 40-week weight loss program. During the first 12 weeks, half the subjects were provided a 1000 kcal/day low-calorie diet (LCD), compromised of portion-controlled foods, whereas the other half were prescribed a 1200 kcal/day balanced deficit diet (BDD) consisting of self-selected table foods. Thereafter, subjects in both conditions were instructed to consume approximately 1200-1800 kcal/day of self-selected foods, depending on their desired weight change. During the first 6 weeks, weight and serum leptin fell significantly more (P < 0.05) in women in the LCD condition than in the BDD condition. In the former group, the 55% reduction in baseline leptin was 10 times greater than the relative reduction in body weight. Stepwise multiple regression analysis revealed that degree of caloric restriction, but not weight loss, contribution significantly to the variance in the change in leptin at week 6. By contrast, long-term changes in leptin, when subjects had increased their calorie intake, were more strongly related to changes in weight and fat. At week 40, for example, weight loss account for 47% of the variance in the change in leptin. Serum leptin and body fat remained highly correlated after weight loss (r = 0.79, P < 0.001), as before (r = 0.66, P < 0.001). After treatment, however, we observed a greater-than-expected reduction in serum leptin concentrations, as expressed per kilogram of body fat. The significance of this finding remains to be determined.

Adipose Tissue↗

PubMed1998

Chromatographic removal and heat inactivation of hepatitis A virus during manufacture of human albumin.

CSL Limited, an Australian biopharmaceutical company, has recently converted its method of manufacture for human albumin from a traditional Cohn-ethanol fractionation method to a method employing chromatographic techniques. Studies were undertaken to determine the efficiency of the chromatographic and pasteurization steps used in the manufacture of Albumex(R) (CSL's trade name for albumin) in removing and inactivating the potential viral contaminant, hepatitis A virus (HAV). The manufacturing process for Albumex(R) includes three chromatographic steps, two of which are ion-exchange steps (DEAE-Sepharose(R) Fast Flow and CM-Sepharose(R) Fast Flow) and the third is a gel-filtration step (Sephacryl(R) S200 HR). The final stage of the Albumex(R) process involves a bulk pasteurization step where product is held at 60 degrees C for 10 h. HAV partitioning experiments on the DEAE-Sepharose(R) FF and CM-Sepharose(R) FF ion-exchange and Sephacryl(R) S200 HR gel-filtration columns were performed with scaled-down models of the production-scale chromatographic Albumex(R) process. Production samples collected before each of the chromatographic steps were spiked with HAV and processed through each of the scaled-down chromatographic columns. Samples collected during processing were assayed and the log10 reduction factors calculated. Inactivation kinetics of HAV were examined during the pasteurization of Albumex(R) 5 and 20 [5% and 20% (w/v) albumin solutions] held at 60 degrees C for 10 h. Log10 reductions for HAV through the DEAE-Sepharose(R) FF, CM-Sepharose(R) FF and Sephacryl(R) S200 HR chromatographic columns were 5.3, 1.5 and 4.2 respectively, whereas a 4.4 and a greater than 3.9 log10 reduction in HAV in Albumex(R) 5 and 20 respectively were achieved during pasteurization.

Chromatography, Gel↗

PubMed1998

Chromatographic removal and heat inactivation of hepatitis B virus during the manufacture of human albumin.

The purpose of the present study was to examine the efficacy of the chromatographic and pasteurization steps, employed in the manufacture of human albumin, in the removal and/or inactivation of hepatitis B virus (HBV). Most human albumins manufactured today are prepared from donor plasma by fractionation methods that use precipitation with cold ethanol. CSL Limited, an Australian biopharmaceutical company, has recently converted its method of manufacture for albumin from a traditional Cohn fractionation method to a method employing chromatographic techniques. A step-by-step validation of virus removal and inactivation was performed on this manufacturing process, which includes a DEAE-Sepharose(R) and CM-Sepharose(R) Fast Flow ion-exchange step, a Sephacryl(R) S200 High-Resolution gel-filtration step and a bulk pasteurization step where product is held at 60 degreesC for 10 h. HBV partitioning experiments were conducted on scaled-down chromatographic columns with hepatitis B surface antigen (HBsAg) as a marker, whereas the HBV model virus, duck HBV, was used to study the inactivation kinetics during pasteurization. Reductions for HBsAg through the three chromatographic steps resulted in a total log10 decrease of 1.5 log10, whereas more than 6.5 log10 decrease in duck HBV in Albumex(R)5 was achieved during pasteurization.

Animals↗

PubMed1997

Amino-terminal epitopes are exposed when full-length open reading frame 2 of hepatitis E virus is expressed in Escherichia coli, but carboxy-terminal epitopes are masked.

We constructed a panel of overlapping and non-overlapping fragments of cDNA derived from open reading frame 2 (ORF2) of hepatitis E virus (HEV) and fused to the gene encoding glutathione S-transferase (GST), from which proteins were expressed in Escherichia coli. IgG-specific immunoreactivity against each protein was measured by Western immunoblotting using sera from experimentally infected Rhesus macaques (Macaca mulatta) or from HEV-infected patients. Under these conditions, full-length ORF2 protein (GST-ORF2) was strongly reactive with acute-phase sera from either macaques or patients, but was poorly reactive with convalescent sera. Recombinant protein GST-ORF2.3, representing amino acids 1-110 of the 660 encoded by ORF2, demonstrated a pattern of reactivity largely indistinguishable from the full-length protein. Conversely, GST-ORF2.1, representing amino acids 394-660 of the ORF2 protein was strongly reactive with both acute- and convalescent-phase sera. Extension of GST-ORF2.1 towards the N-terminus led to a progressive loss of convalescent-phase reactivity, apparent with as few as 20 additional HEV-specific amino acids. Deletion of 40 or more amino acids from the N-terminus of ORF2.1 also led to reduced convalescent-phase reactivity, however a protein representing this "reactive" region, containing amino acids 394-473, was poorly reactive, suggesting that the convalescent-reactive epitopes are conformational. Expression of full-length ORF2 protein in E. coli therefore masks the convalescent-reactive epitopes within the C-terminal part of the protein, without affecting N-terminal, acute-reactive epitopes.

Animals↗

PubMed1997

Dietary and exercise interventions for juvenile obesity: long-term effect of behavioral and public health models.

We investigated the influence of nutrition and exercise interventions within cognitive/behavioral and public health formats on weight and blood lipid profiles in obese children. Compliance was also examined as well as the relationship of the compliance measures with clinical outcome variables. Three conditions were compared over 16 sessions: nutrition and eating-habit change followed by exercise (NE), exercise followed by nutrition and eating-habit change (EN), and an information control (INFO). NE and EN were presented in a cognitive/ behavioral framework which focused on the development of self-regulation whereas the INFO condition received the same material in a public health/educational model. NE and EN participants evidenced modest, yet significant, reductions in weight and blood lipids, and the impact of these two interventions endured at a five-year follow-up. In contrast, INFO participants displayed stable weight and blood lipids during the course of the program, and most remained morbidly obese at follow-up. Improved nutrition, increased physical activity and fitness were significantly correlated with weight and lipid reductions.

Adolescent↗

PubMed1997

Hepatitis A virus subviral particles: purification, accumulation, and relative infectivity of virions, provirions and procapsids.

Virus-specific particles were isolated from hepatitis A virus (HAV)-infected cells and the role of each particle type in the replicative cycle assessed. Mature virions, provirions (immature virions) and empty capsids (procapsids) were detected in cell lysates, and both virions and provirions were found in the culture supernatant. Particle types were separated by isopycnic caesium chloride gradient or linear sucrose density gradient-ultracentrifugation, and their capsid proteins characterised. Virions, provirions and procapsids containing both VP1 and varying levels of the VP1 precursor protein PX were found, suggesting that trimming of PX is not essential for particle formation. Provirions (containing VP0) and virions (containing VP2) could not be clearly separated with these techniques, but sucrose gradients allowed greater separation of particle pools with distinct VP0 contents and specific infectivities which could be used for further studies of the biological role of VP0 cleavage. Virions, with a higher sedimentation coefficient and buoyant density presumably reflecting a more compact structure, had a higher relative infectivity when compared to provirions. HAV-infected cells therefore contain a heterogenous mixture of RNA-containing viral particles with characteristics between those of true provirions and virions, but all such particles are released from the cell and can participate in further rounds of infection.

Animals↗