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Biomedical subjects

J R Powers

Publications and source records attributed to J R Powers.

At least 19 recordsLinked to original sources
PubMed2006

Cheese pH, protein concentration, and formation of calcium lactate crystals.

The occurrence of calcium lactate crystals (CLC) in hard cheeses is a continual expense to the cheese industry, as consumers fail to purchase cheeses with this quality defect. This research investigates the effects of the protein concentration of cheese milk and the pH of cheese on the occurrence of CLC. Atomic absorption spectroscopy was used to determine total and soluble calcium concentrations in skim milk (SM1, 8.7% total solids), and skim milk supplemented with nonfat dry milk (CSM1, 13.5% total solids). Calcium, phosphorus, lactic acid, and citrate were determined in cheeses made with skim milk (SM2, 3.14% protein), skim milk supplemented with ultrafiltered milk (CSM2, 6.80% protein), and nonfat dry milk (CSM3, 6.80% protein). Supplementation with nonfat dry milk increased the initial total calcium in CSM1 (210 mg/100 g of milk) by 52% compared with the total calcium in SM1 (138 mg/100 g of milk). At pH 5.4, soluble calcium concentrations in CSM1 were 68% greater than soluble calcium in SM1. In cheeses made from CSM2 and CSM3, total calcium was 26% greater than in cheeses made from SM2. As the pH of cheeses made from SM2 decreased from 5.4 to 5.1, the concentration of soluble calcium increased by 61.6%. In cheeses made from CSM2 and CSM3, the concentrations of soluble calcium increased by 41.4 and 45.5%, respectively. Calcium lactate crystals were observed in cheeses made from SM2 at and below pH 5.1, whereas CLC were observed in cheeses from CSM2 and CSM3 at and below pH 5.3. The increased presence of soluble calcium can potentially cause CLC to occur in cheese manufactured with increased concentrations of milk solids, particularly at and below pH 5.1.

Animals↗
PubMed2005

Differences in mail and telephone responses to self-rated health: use of multiple imputation in correcting for response bias.

OBJECTIVES: To estimate differences in self-rated health by mode of administration and to assess the value of multiple imputation to make self-rated health comparable for telephone and mail. METHODS: In 1996, Survey 1 of the Australian Longitudinal Study on Women's Health was answered by mail. In 1998, 706 and 11,595 mid-age women answered Survey 2 by telephone and mail respectively. Self-rated health was measured by the physical and mental health scores of the SF-36. Mean change in SF-36 scores between Surveys 1 and 2 were compared for telephone and mail respondents to Survey 2, before and after adjustment for sociodemographic and health characteristics. Missing values and SF-36 scores for telephone respondents at Survey 2 were imputed from SF-36 mail responses and telephone and mail responses to sociodemographic and health questions. RESULTS: At Survey 2, self-rated health improved for telephone respondents but not mail respondents. After adjustment, mean changes in physical health and mental health scores remained higher (0.4 and 1.6 respectively) for telephone respondents compared with mail respondents (-1.2 and 0.1 respectively). Multiple imputation yielded adjusted changes in SF-36 scores that were similar for telephone and mail respondents. CONCLUSIONS AND IMPLICATIONS: The effect of mode of administration on the change in mental health is important given that a difference of two points in SF-36 scores is accepted as clinically meaningful. Health evaluators should be aware of and adjust for the effects of mode of administration on self-rated health. Multiple imputation is one method that may be used to adjust SF-36 scores for mode of administration bias.

Attitude to Health↗
PubMed2005

Enhanced lactose cheese milk does not guarantee calcium lactate crystals in finished cheddar cheese.

Three experimental batches of Cheddar cheese were manufactured in duplicate, with standardization of the initial cheese-milk lactose content to high (5.24%), normal (4.72%, control), and low lactose (3.81%). After 35 d of aging at 4.4 degrees C, the cheeses were subjected to temperature abuse (24 h at 21 degrees C, unopened) and contamination (24 h at 21 degrees C, packages opened and cheeses contaminated with crystal-containing cheese). After aging for 167 d, residual cheese lactose (0.08 to 0.43%) and L(+)-lactate concentrations (1.37 to 1.60%) were high and D(-)-lactate concentrations were low (<0.03%) for all cheeses. No significant differences in lactose concentrations were attributable to temperature abuse or contamination. No significant differences in L(+)- or D(-)-lactate concentrations were attributable to temperature abuse. However, concentrations of L(+)-lactate were significantly lower and D(-)-lactate were significantly higher in contaminated cheeses than in control cheeses, indicating inoculation (at d 35) with heterofermentative nonstarter lactic acid bacteria able to racemize L(+)-lactate to D(-)-lactate. The fact that none of the cheeses exhibited crystals after 167 d demonstrates that high cheese milk or residual lactose concentrations do not guarantee crystal formation. Contamination with nonstarter lactic acid bacteria can significantly contribute to D(-)-lactate accumulation in cheese.

Animals↗
PubMed2001

Beta-lactoglobulin molten globule induced by high pressure.

Beta-lactoglobulin (beta-LG) was treated with high hydrostatic pressure (HHP) at 600 MPa and 50 degrees C for selected times as long as 64 min. The intrinsic tryptophan fluorescence of beta-LG indicated that HHP treatment conditions induced a conformational change. HHP treatment conditions also promote a 3-fold increase in the extrinsic fluorescence of 1-anilinonaphthalene-8-sulfonate and a 2.6-fold decrease for cis-paraneric acid, suggesting an increase in accessible aromatic hydrophobicity and a decrease in aliphatic hydrophobicity. Far-ultraviolet circular dichroism (CD) spectra reveal that the secondary structure of beta-LG converts from native beta-sheets to non-native alpha-helices following HHP treatment, whereas near-ultraviolet CD spectra reveal that the native tertiary structure of beta-LG essentially disappears. Urea titrations reveal that native beta-LG unfolds cooperatively, but the pressure-treated molecule unfolds noncooperatively. The noncooperative state is stable for 3 months at 5 degrees C. The nonaccessible free thiol group of cysteine121 in native beta-LG became reactive to Ellman's reagent after adequate HHP treatment. Gel electrophoresis with and without beta-mercaptoethanol provided evidence that the exposed thiol group was lost concomitant with the formation of S-S-linked beta-LG dimers. Overall, these results suggest that HHP treatments induce beta-LG into hydrophobic molten globule structures that remain stable for at least 3 months.

Electrophoresis, Agar Gel↗
PubMed2001

Preventing tractor rollover fatalities: performance of the NIOSH autoROPS.

Approximately 132 agricultural tractor overturn fatalities occur per year. The use of rollover protective structures (ROPS), along with seat belts, is the best known method for preventing these fatalities. One impediment to ROPS use, however, is low clearance situations, such as orchards and animal confinement buildings. To address the need for ROPS that are easily adapted to low clearance situations, the Division of Safety Research, National Institute for Occupational Safety and Health (NIOSH), developed an automatically deploying, telescoping ROPS (Auto-ROPS). The NIOSH AutoROPS consists of two subsystems. The first is a retractable ROPS that is normally latched in its lowered position for day-to-day use. The second subsystem is a sensor that monitors the operating angle of the tractor. Ifa rollover condition is detected by the sensor, the retracted ROPS will deploy and lock in the full upright position before ground contact. Static load testing and field upset tests of the NIOSH AutoROPS have been conducted in accordance with SAE standard J2194. Additionally, timed trials of the AutoROPS deployment mechanism were completed. The design of the retractable ROPS and sensor, as well as the results of the different testing phases are discussed.

Accident Prevention↗
PubMed2001

Performance of an automatically deployable ROPS on ASAE tests.

In the U.S., approximately 132 agricultural tractor overturn fatalities occur per year. The use of rollover protective structures (ROPS), along with seat belts, is the best-known method for preventing these fatalities. However, one impediment to ROPS use is low-clearance situations, such as orchards and animal confinement buildings. To address the need for ROPS that are easily adapted to low-clearance situations, the Division of Safety Research, National Institute for Occupational Safety and Health, developed a prototype automatically deploying, telescoping ROPS (AutoROPS). The NIOSH AutoROPS consists of two subsystems. The first is a retractable ROPS that is normally latched in its lowered position for day-to-day use. The second subsystem is a sensor that monitors the operating angle of the tractor. If an overturn condition is detected by the sensor, the retracted ROPS will deploy and lock in the full upright position before ground contact. Static load testing and field upset tests of the NIOSH AutoROPS have been conducted in accordance with SAE standard J2194. Additionally, timed trials of the AutoROPS deployment mechanism were completed. The results of these tests show that the NIOSH AutoROPS has significant potential to overcome the limitations of current ROPS designs for use in low clearance as well as unrestricted clearance operations.

Accident Prevention↗
PubMed2000

Iron deficiency, general health and fatigue: results from the Australian Longitudinal Study on Women's Health.

Associations between self-reported 'low iron', general health and well-being, vitality and tiredness in women, were examined using physical (PCS) and mental (MCS) component summary and vitality (VT) scores from the MOS short-form survey (SF-36). 14,762 young (18-23 years) and 14,072 mid-age (45-50 years) women, randomly selected from the national health insurance commission (Medicare) database, completed a baseline mailed self-report questionnaire and 12,328 mid-age women completed a follow-up questionnaire 2 years later. Young and mid-age women who reported (ever) having had 'low iron' reported significantly lower mean PCS, MCS and VT scores, and greater prevalence of 'constant tiredness' at baseline than women with no history of iron deficiency [Differences: young PCS = -2.2, MCS = -4.8, VT = -8.7; constant tiredness: 67% vs. 45%; mid-age PCS = -1.4, MCS = -3.1, VT = -5.9; constant tiredness: 63% vs. 48%]. After adjusting for number of children, chronic conditions, symptoms and sociodemographic variables, mean PCS, MCS and VT scores for mid-age women at follow-up were significantly lower for women who reported recent iron deficiency (in the last 2 years) than for women who reported past iron deficiency or no history of iron deficiency [Means: PCS--recent = 46.6, past = 47.8, never = 47.7; MCS--recent = 45.4, past = 46.9, never = 47.4; VT--recent = 54.8, past = 57.6, never = 58.6]. The adjusted mean change in PCS, MCS and VT scores between baseline and follow-up were also significantly lower among mid-age women who reported iron deficiency only in the last 2 years (i.e. recent iron deficiency) [Mean change: PCS = -3.2; MCS = -2.1; VT = -4.2]. The results suggest that iron deficiency is associated with decreased general health and well-being and increased fatigue.

Adolescent↗
PubMed2000

Adverse events during use of intranasal desmopressin acetate for haemophilia A and von Willebrand disease: a case report and review of 40 patients.

We report our experience with the incidence of adverse events during the use of Stimate brand intranasal desmopressin acetate (IN DDAVP) for patients with haemophilia A (HA) or von Willebrand disease (vWD) after noting two severe adverse events in one adult patient. All patients with documented vWD (type 1 or 2 A) or haemophilia A (mild, moderate or symptomatic carrier) from the Emory Comprehensive Hemophilia Center who had IN DDAVP challenge testing or were using Stimate for treatment of bleeding were evaluated for adverse events by patient report or nursing observation of clinical signs and symptoms. Forty patients were studied. Sixty-eight per cent (27/40) experienced clinical signs and/or symptoms. The majority of these symptoms were mild, however several patients reported moderate to severe side-effects and one adult patient required medical intervention for symptomatic hyponatraemia. In our experience, two-thirds of patients tested experienced adverse signs and/or symptoms with the use of Stimate; considerably higher than that reported from preliminary results in the literature. Young age did not correlate positively with adverse reactions. Severe adverse events requiring medical intervention were rare, however symptoms such as moderate to severe headache, nausea, vomiting and weakness may necessitate evaluation for hyponatraemia. This is the first report of symptomatic hyponatraemia in an adult patient with recommended dosing of Stimate. Side-effects may be minimized if patients adhere to instructions regarding fluid intake and composition while using IN DDAVP.

Administration, Intranasal↗
PubMed2000

A new video-synchronized multichannel biomedical data acquisition system.

This data acquisition system records video frames onto a video tape, and simultaneously acquires biomedical data along with video time codes onto a computer hard disk to achieve a 30-min video-synchronized data recording with a summed data rate of 2.16 Mbit/s. A time-code-bridge-file created during acquisition matches each video frame-start with the corresponding index number of the acquired data. The mean synchronization accuracy of the system is 0.22 ms.

Computer Graphics↗
PubMed1996

Cardiac pathology and adult aboriginal mortality: a coronial study of sudden and external cause deaths in the top end of the Northern Territory in 1990.

A retrospective review of coronial records was performed for 179 adult decedents who came to coronial autopsy in 1990 and who had been living in the Top End of the Northern Territory at the time of death. The directly standardized rate of autopsy-examined sudden death was 7.4 times higher for Aboriginal people than for non-Aboriginal people. Coronary atherosclerosis was the cause of 37% (14/38) of the Aboriginal sudden deaths and 52% (16/31) of the non-Aboriginal sudden deaths. Evidence of coronary atherosclerosis rose with age and was seen more frequently in those dying suddenly compared to those dying of external causes. When directly standardized, the rate of autopsy-examined sudden death attributable to ischemic heart disease was 5.5 times higher for Aboriginal people than for non-Aboriginal people. Contrary to a previously published statement, there is considerable overlap between Aboriginal and non-Aboriginal heart weights, with 75% (55/73) of Aboriginal decedents and 84% (89/106) of non-Aboriginal decedents having heart weights between 250 and 500 g. We concluded that the rate of autopsy-examined sudden death from all causes, and specifically from ischemic heart disease, was much higher in Aboriginal people. However in a case of sudden death a presumptive clinical diagnosis of ischemic heart disease prior to autopsy is not justified in either Aboriginal or non-Aboriginal people, due to the high prevalence of other fatal conditions. The diagnosis of pathologically increased heart weight, which is critical in the assessment of sudden death, should be made on the same basis in both Aboriginal and non-Aboriginal people.

Adolescent↗
PubMed1996

Physical association of starch biosynthetic enzymes with starch granules of maize endosperm. Granule-associated forms of starch synthase I and starch branching enzyme II.

Antibodies were used to probe the degree of association of starch biosynthetic enzymes with starch granules isolated from maize (Zea mays) endosperm. Graded washings of the starch granule, followed by release of polypeptides by gelatinization in 2% sodium dodecyl sulfate, enables distinction between strongly and loosely adherent proteins. Mild aqueous washing of granules resulted in near-complete solubilization of ADP-glucose pyrophosphorylase, indicating that little, if any, ADP-glucose pyrophosphorylase is granule associated. In contrast, all of the waxy protein plus significant levels of starch synthase I and starch branching enzyme II (BEII) remained granule associated. Stringent washings using protease and detergent demonstrated that the waxy protein, more than 85% total endosperm starch synthase I protein, and more than 45% of BEII protein were strongly associated with starch granules. Rates of polypeptide accumulation within starch granules remained constant during endosperm development. Soluble and granule-derived forms of BEII yielded identical peptide maps and overlapping tryptic fragments closely aligned with deduced amino acid sequences from BEII cDNA clones. These observations provide direct evidence that BEII exits as both soluble and granule-associated entities. We conclude that each of the known starch biosynthetic enzymes in maize endosperm exhibits a differential propensity to associate with, or to become irreversibly entrapped within, the starch granule.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1996

The effect of retail store managers on aboriginal diet in remote communities.

Key nutrient densities of the diet of two remote northern coastal Aboriginal communities were measured using the store-turnover method during the periods that three store managers were responsible for each store respectively. Individual store managers were a greater determinant of nutrient density than the community itself. Furthermore, nutrient densities tended to be highest in both communities when their stores were administered by one particular store manager. The results support the notion that store managers wield considerable power over the food supply of remote Aboriginal communities, and raise questions concerning the ability of Aboriginal community members to influence their own food supplies in retail stores. However, the study also confirms that store managers can be important allies in efforts to improve Aboriginal dietary intake.

Analysis of Variance↗
PubMed1996

An evaluation of unleaded petrol as a harm reduction strategy for petrol sniffers in an aboriginal community.

OBJECTIVE: In mid 1989, leaded petrol was replaced by unleaded petrol to reduce lead toxicity in petrol sniffers in Maningrida, a remote Aboriginal community in Northern Australia. RETROSPECTIVE REVIEWS: Hospital admissions between 1987 and 1992 due to petrol sniffing were compared for Maningrida and a community using only leaded petrol. RESULTS: Admissions from Maningrida decreased significantly following introduction of unleaded petrol (chi 2 on 2df = 22.25, p < 0.001). Lead and hydrocarbon exposures were also compared for three groups from Maningrida (27 sniffers using only unleaded petrol; 15 exsniffers and 13 nonsniffers) and 24 individuals admitted to hospital for petrol sniffing related illness from other communities using only leaded petrol. Median blood lead levels for hospitalized sniffers (using only leaded petrol). Maningrida sniffers (using only unleaded petrol), exsniffers and nonsniffers were 5.06, 1.87, 1.24 and 0.17 microM/L respectively. There were significant differences between blood lead level, delta-aminolevulinic acid dehydratase activity, and free erythrocyte protoporphyrin for sniffers of leaded and unleaded petrol, whereas these indices were not significantly different for current sniffers and exsniffers in Maningrida. Hydrocarbons were only detectable in the blood of active sniffers (toluene < or = 0.5 micrograms/mL; benzene < or = 0.17 micrograms/mL blood; n-hexane not detected). CONCLUSIONS: The elimination of tetraethyl lead from petrol resulted in a significant decrease in hospitalization of petrol sniffers.

Adolescent↗
PubMed1995

Wrist postures while keyboarding: effects of a negative slope keyboard system and full motion forearm supports.

Video-motion analysis was used to analyse hand/wrist posture for subjects typing at a 101-key QWERTY keyboard on a 68 cm high worksurface. Three conditions were tested: subjects typed at the keyboard without arm support, subjects typed with adjustable full motion forearm supports, and subjects typed with an adjustable negative slope keyboard support system. The average declination of the negative slope keyboard support chosen by subjects was 12 degrees below horizontal, which flattened the angle of the key tops. Ulnar deviation was comparable in all conditions and averaged 13 degrees for the right hand and 15 degrees for the left hand. Full motion forearm supports did not significantly affect any postural measures. Dorsal wrist extension averaged 13 degrees when typing with or without the full motion forearm supports, but this was reduced to an average -1 degree with the use of the negative slope keyboard support system. Subjects chose to sit at a distance of 79 cm from the computer screen when using the negative slope keyboard system compared with 69 cm without this.

Adult↗
PubMed1994

Elevated serum creatine kinase (CK-MM) in petrol sniffers using leaded or unleaded fuel.

This study examined blood lead and creatine kinase levels in a group of 24 Australian Aboriginal males admitted to the hospital for treatment of severe petrol sniffing related illness after using only leaded petrol and 27 sniffers, 16 ex-sniffers and 13 non-sniffers from an isolated Aboriginal community using only unleaded petrol. Creatine kinase levels (which were nearly all creatine kinase-skeletal muscle isoenzyme indicating skeletal muscle damage) were correlated with blood lead levels and were elevated in active sniffers of leaded petrol on admission to hospital but were also increased in those sniffing unleaded petrol in the remote community. After fourteen days in hospital, median creatine kinase levels of leaded petrol sniffers dropped rapidly to levels similar to those of ex-sniffers and non-sniffers while median blood lead levels decreased but still remained higher than the other three groups. The data suggest that elevated creatine kinase associated with petrol sniffing may be due to compounds in petrol other than the lead additives, possibly volatile hydrocarbon components. Elevated creatine kinase may be useful in detecting current petrol sniffing activity, particularly in locations using unleaded petrol.

Adolescent↗
PubMed1993

Birth size of Australian aboriginal babies.

OBJECTIVES: (i) To describe birth size of Aboriginal babies by sex, gestational age, and Aboriginality; (ii) to analyse the results with reference to standards of ponderal index and birthweight for gestational age. SUBJECTS: 570 liveborn singletons routinely delivered at Royal Darwin Hospital between January 1987 and March 1991, and recorded in the Delivery Suite Register as being born to an Aboriginal mother. MAIN OUTCOME MEASURES: Weight, length and head circumference at birth. RESULTS: The mean birthweight was 3098 g (standard deviation, 601 g), peak gestational age was 39 weeks, 13% were low birthweight and 7% were preterm. Preterm rates did not differ significantly for sex and Aboriginality. Babies without a non-Aboriginal ancestor had a lower mean birthweight and at term, were significantly smaller than babies with a non-Aboriginal ancestor as assessed by mean birthweight, length, head circumference and ponderal index. More than a quarter of babies (27%) without a non-Aboriginal ancestor were below the 10th percentile of birthweight for gestational age, compared with 14.2% of babies with a non-Aboriginal ancestor. CONCLUSIONS: On the basis of postnatal clinical estimates of gestational age, Aboriginal babies have a preterm rate of 7% and Aboriginal babies without a non-Aboriginal ancestor are smaller in size at birth than babies with a non-Aboriginal ancestor.

Australia↗
PubMed1992

Hospitalisation patterns in children from 10 aboriginal communities in the Northern Territory.

OBJECTIVE: To describe childhood hospitalisation patterns in rural Aboriginal communities in the Northern Territory. DESIGN: Longitudinal data for 1976-1985 were collected retrospectively between March 1986 and December 1987. COHORT: All children born between 1 January 1976 and 31 December 1985 and identified in records at 10 community health centres were included in the study, except for 30 children who were residents of more than one community. Records of hospital admissions were ascertained for the remaining 2254 children until five years of age or 31 December 1985, whichever was earlier. RESULTS: Mean admission rates for Aboriginal children aged 0-1 year were two to three times the national average, and there was a fourfold excess in the number of days in hospital and the number of deaths before the age of five years for Aboriginal infants. Admission rates varied by community, age, year and sex: at 0-6 months of age, rates for communities ranged from a minimum of 0.21 to a maximum of 1.46 admissions per child-year at risk and mean rates increased from 0.50 per year in 1976 to 1.05 in 1985; mean admission rates declined from 0.84 per child-year at age 0-6 months to 0.12 at age 37-60 months. Boys were admitted to hospital more frequently than girls. For communities, hospital stay ranged from a minimum of 2.7 to a maximum of 15.3 hospital days per child-year at risk. CONCLUSIONS: Differences of up to sevenfold in hospitalisation rates between communities highlight the potential for primary and secondary prevention of childhood disease in Aboriginal communities.

Anemia↗