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Biomedical subjects

M Harkins

Publications and source records attributed to M Harkins.

11 recordsLinked to original sources
PubMed2004

Comparison of pulmonary function between children living in rural and urban areas in northern Nigeria.

Children in northern Nigeria and elsewhere in the hot, arid western Sahel, are at risk of having their lung function compromised by a variety of factors, including undernutrition, environmental factors (e.g. airborne pollutants such as dust and smoke from wood fires), chronic upper-respiratory tract infections, and low socioeconomic class. We were interested in using spirometry to compare the pulmonary function of Nigerian children and adolescents aged 6-18 years who were living in urban and rural settings with the corresponding standards for African-American children. A total of 183 boys and girls in the rural village of Sabon Fobur on the Jos Plateau and another 128 boys and girls in the city of Jos were tested to determine their forced vital capacity (FVC), FVC at 1 s (FVC1), and peak expiratory flow (PEF). The nutritional status of the subjects was determined by measuring the body mass index (BMI), triceps skin-fold thickness, and mid-arm circumference, and fat-free mass (FFM) and fat mass (FM) by bioelectrical impedance analysis. According to the results of anthropometry, the subjects in Sabon Fobur and Jos were lean but generally adequately nourished. The mean FVC, FVC1 and PEF values for the rural males were 1.851,1.761, and 3.521, and for the urban males they were 1.971,1.791, and 3.471, respectively. The corresponding values for the rural females were 1.791,1.701, and 3.371, and for the urban females they were 1.761,1.671, and 3.091. These values were approximately 100 per cent of the corresponding values for African-American children. In general, strong correlations were found between each of the three lung function parameters and age, weight, height (only for the males), BMI, MAC, and FFM. These results show that: (1) the lung function of Nigerian children and adolescents living in either rural or urban areas were similar and compared favorably with African-American standards, and (2) weight was as important as height in determining pulmonary function. The inclusion of FFM as an explanatory variable did notfurther increase the accuracy of the prediction, even in a population where malnutrition may be prevalent. Therefore, we conclude that measurements of height and weight are all that are required for the assessment of lung function using spirometry in Nigerian children.

Adolescent↗
PubMed2004

The role of host organism, transcriptional switches and reporter mechanisms in the performance of Hg-induced biosensors.

AIMS: The purpose of this study was to comprehensively compare the response of nine biosensors capable of being induced by Hg. Induction by Hg was based upon the insertion of merR, merB, zntA and zntR promoter genes. LuxCDABE or lucFF reporter genes expressed luminescence, and host organisms were Escherichia coli, Vibrio anguillarum and Pseudomonas fluorescens. The role of transcriptional switches, reporter mechanism and host organism was to be investigated. METHODS AND RESULTS: All biosensors were subjected to the same assay conditions. Sensors had their own individual growth characteristics and response to the doses of Hg tested. Maximum bioluminescence response was induced by concentrations of Hg between 2.5 nm and 5 microM. E. coli pRB28 was found to detect levels of Hg as low as 1.6 nm and yet was capable of operating in a concentration range of up to 12.5 microM. CONCLUSIONS: The response of the sensors demonstrated their suitability for analysis under environmentally relevant concentrations. The sensitivity of the sensors, the optimum range and the expediency of the assay could not be related to a single sensor trait. It may be concluded that biosensor performance is dependent on more than one of the single factors studied. SIGNIFICANCE AND IMPACT OF THE STUDY: The results show that comparative testing of sensors is an important step in evaluating the relevance and performance of biosensors prior to routine environmental application.

Biological Availability↗
PubMed1994

Nutrient utilization and protein turnover in the hindlimb of cattle treated with bovine somatotropin.

Our objectives were to assess the effects of chronic administration of recombinant bovine somatotropin (bST) on nutrient utilization and protein turnover in the hindlimb of growing Holstein steers. External iliac vessels were catheterized to allow for hindlimb measurements of arteriovenous differences and blood flow. Animals were used in a single-reversal design with 16-d treatment periods of daily intramuscular injection of either excipient or 120 micrograms/kg body wt of bST. On d 11 and 13 of each period, a primed-continuous infusion of L-[sidechain-2,3-3H]tyrosine was initiated, followed by a 4-h sampling period to assess hindlimb nutrient utilization and protein kinetics. Somatotropin did not alter blood flow or the consumption of acetate and oxygen across the hindlimb. In contrast, glucose uptake was reduced by 22% despite increases in arterial concentrations of glucose and insulin of 10 and 114%, respectively. Treatment with bST increased hindlimb protein accretion (estimated from net uptake of tyrosine) and whole-body N balance, each by approximately 40%. A modest increase (10%) in the absolute rate of protein synthesis seemed to account for the improved N retention in the hindlimb with no change in the rate of protein degradation. Thus, bST reduced the responses of the hindlimb to insulin, and a small alteration in protein synthesis was sufficient to explain substantial improvement in protein deposition.

Amino Acids↗
PubMed1993

Evaluation of the arteriovenous difference technique to simultaneously estimate protein synthesis and degradation in the hindlimb of fed and chronically underfed steers.

Our objectives were to validate a technique to measure protein turnover based on net fluxes of tyrosine radioactivity and mass across the hindlimb, and to describe the impact of nutrition on hindlimb protein kinetics and nutrient utilization in growing Holstein steers. External iliac vessels were catheterized to allow for measurements of hindlimb arteriovenous (AV) differences and blood flow. Animals were used in a single reversal design with 16-d periods. Treatments were either 60% (0.6M) or 220% (2.2M) of the energy required for maintenance. On d 12 and 14 of each period, a primed-continuous infusion of L-[side chain-2,3-3H]tyrosine was initiated, followed by a 4-h sampling period to assess hindlimb nutrient utilization and protein kinetics. Well-fed steers exhibited rates of hindlimb utilization for non-nitrogenous energy substrates and amino acids that were consistent with values previously reported for well-fed ruminants. Underfeeding decreased hindlimb blood flow (62%), oxygen consumption (51%) and utilization of respiratory fuels (64-73%). Protein synthesis was also reduced (49%), leading to net nitrogen loss from the hindlimb. The estimated energy cost of protein synthesis accounted for 13% of hindlimb oxygen consumption across intake levels. Hindlimb protein balance was consistent with whole-body balance, adding credence to derived rates of degradation. Overall, data support the validity of the AV difference technique to estimate components of hindlimb protein turnover.

Animals↗
PubMed1990

Preparation for human study of pesticide applicators: sister chromatid exchanges and chromosome aberrations in cultured human lymphocytes exposed to selected fumigants.

In preparation for a human study of worker exposure to grain fumigants and pesticides, we decided to screen commonly used fumigants for genotoxic effects in vitro. This research strategy was employed to test the possibility that structurally simple chemicals might have similar genotoxic properties in vivo and in vitro. As a first step, we designed our in vitro protocol to mimic to the extent possible, a single in vivo exposure of lymphocytes to fumigants. Go lymphocytes were treated with different doses of carbon tetrachloride, carbon disulfide, methyl bromide, chloropicrin, and melathion with and without addition of rat liver homogenate for 1/2 hour, washed free of toxicant, and stimulated with PHA. After culture, the prepared slides were studied for chromosome aberrations and SCEs. Malathion, methyl bromide, and chloropicrin significantly induced SCEs without S-9. Carbon disulfide alone required S-9 for significant SCE induction. Chromosome aberrations were significantly increased by malathion and methyl bromide. Carbon tetrachloride failed to induce SCEs or chromosome aberrations with or without S-9. We concluded from these preliminary studies and other comparable work that the fumigants studied here may be less likely to express genotoxicity in terms of SCEs or chromosome aberrations than ethylene oxide or phosphine given a single short-term in vivo exposure. The final design of our human study was altered to focus on seasonal worker exposure rather than on a single exposure event.

Adult↗
PubMed1990

Effect of dose of bovine somatotropin on nutrient utilization in growing dairy heifers.

Growing Holstein heifers [n = 6; 104 kg initial body weight (BW)] were used to investigate the effects of a daily dose (0, 6.7, 33, 67, 100 and 200 micrograms/kg BW) of bovine somatotropin (bST) on nutrient utilization. A Latin square design was used, and treatments (daily doses of bST) were administered by intramuscular injection for 14-d periods. Intakes of a total mixed ration were adjusted according to BW at the start of each period. Energy was supplied to allow an estimated daily gain of 0.75 kg, and crude protein intake was increased 15% above recommendations to allow for anticipated increases in protein deposition with bST treatment. Nitrogen balance and nutrient digestibilities were determined on d 7 to 13, and blood samples were obtained on d 14 of treatment. Digestibilities of dry matter, organic matter and N were similar (70 +/- 1%) and not affected by treatments (p greater than 0.1). Nitrogen retention increased, and plasma urea N and urinary N excretion decreased in a dose-dependent manner. Retention of N in heifers receiving the highest bST dose was 23% greater (p less than 0.001) than the zero dose treatment. Serum concentration of insulin-like growth factor I (IGF-I) was also increased with bST treatment in a curvilinear dose-dependent manner. Plasma glucose increased (5 to 8%, p less than 0.001) with the three highest doses of bST, but serum concentration of insulin was not altered.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effect of recombinant porcine somatotropin on lactational performance and metabolite patterns in sows and growth of nursing pigs.

Sixteen crossbred sows (Yorkshire x Duroc) were used to determine the effect of recombinantly derived porcine somatotropin (pST) on lactational performance and the pattern of plasma metabolites and growth rate of nursing pigs. Daily s.c. injections of either pST (8.22 mg.sow-1.d-1) or excipient were administered at 1000 on d 12 through d 29 of lactation. Jugular cannulas were inserted in three sows/treatment and hourly blood samples were collected on d 11 to 13 and d 28 to 29 of lactation to determine the effect of treatment on plasma concentrations of somatotropin, glucose and nonesterified fatty acids in plasma. Milk production and weight of nursing pigs were determined pretreatment (d 9 and 10) and on d 16, 22 and 28. Milk production of sows receiving pST progressively increased above that of control sows and was 22% greater on d 28. Milk composition was not affected by treatment with pST (P greater than .10), so that the increase in yields of milk fat, lactose and solids paralleled the increases in milk yield. Total milk protein yield tended to be higher in sows receiving pST, but protein yield was greater (P less than .10) only on d 28. Pigs suckling sows treated with pST weighed .34 kg more at the end of the lactation period (P less than .05). Sows receiving pST consumed less feed (P less than .05) during the treatment period, and, as a result, lost more weight (P less than .10) and backfat (P less than .05) than control sows. Average concentrations of plasma somatotropin were elevated approximately 2.5-fold above baseline levels by exogenous pST. No acute alterations in plasma glucose or nonesterified fatty acids were observed in response to pST treatment, however, sows receiving pST had a chronic elevation of plasma glucose on d 29 of lactation.

Animals↗