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Biomedical subjects

L Larsen

Publications and source records attributed to L Larsen.

82 records · Page 5Linked to original sources
PubMed1975

Iron absorption in patients with chronic renal failure not requiring dialytic therapy.

Gastrointestinal iron absorption, by means of whole body counting, has been measured in 15 patients with chronic renal failure, not requiring dialysis. Whole body retention 14 days after oral administration of 10 muCi 59Fe together with a carrier dose of 10 mg Fe2+ was taken as expression of absorption. The percentage incorporation in the total erythrocyte mass of administered 59Fe (erythrocyte incorporation) and absorbed 59Fe (red cell utilization) was estimated as well. Iron absorption was 9.6+/-2.0 (S.D.)% (geometric mean) and erythrocyte incorporation 7.5+/-2.3 (S.D.)% (geometric mean) while red cell utilization averaged 80.3+/-4.8 (S.E.M.)% (arithmetic mean). None of these parameters were significantly different from those obtained in a normal control group (p greater than 0.5, p greater than 0.9 and p greater than 0.2, respectively). The correlation between iron absorption and erythrocyte incorporation was highly significant (r=1.00, p less than 0.001). Iron supplementation is often indicated in the investigated category of patients due to increased blood loss and insufficient iron intake and should be given orally in consideration of the normal gastrointestinal absorption.

Erythrocytes↗
PubMedDate not supplied

Potential mineralization of four herbicides in a ground water--fed wetland area.

Herbicides may leach from agricultural fields into ground water feeding adjacent wetlands. However, only little is known of the fate of herbicides in wetland areas. The purpose of the study was to examine the potential of a riparian fen to mineralize herbides that could leach from an adjacent catchment area. Slurries were prepared from sediment and ground water collected from different parts of a wetland representing different redox conditions. The slurries were amended with O2, NO3-, SO4(2-), and CO2, or CO2 alone as electron acceptors to simulate the in situ conditions and their ability to mineralize the herbides mecoprop, metsulfuron-methyl, isoproturon and atrazine. In addition, the abundance of bacteria able to utilize O2, NO3-, SO4(2-) + CO2, and CO2 as electron acceptors was investigated along with the O2-reducing and methanogenic potential of the sediment. The recalcitrance to bacterial degradation depended on both the type of herbicide and the redox conditions pertaining. Mecoprop was the most readily degraded herbicide, with 36% of [ring-U-14C]mecoprop being mineralized to 14CO2 under aerobic conditions after 473 d. In comparison, approximately 29% of [phenyl-U-14C]metsulfuron-methyl and 16% of [ring-U-14C]isoproturon mineralized in aerobic slurries during the same period. Surprisingly, 8 to 13% of mecoprop also mineralized under anaerobic conditions. Neither metsulfuron-methyl nor isoproturon were mineralized under anaerobic conditions and atrazine was not mineralized under any of the redox conditions examined. The present study is the first to report mineralization of meco-prop in ground water in a wetland area, and the first to report mineralization of a phenoxyalcanoic acid herbicide under both aerobic and anaerobic conditions.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMedDate not supplied

Development and psychometric evaluation of the Caregiver Reciprocity Scale II.

Caregiver reciprocity is the collective affective and behavioral expression of exchanges given and received between a caregiver and care receiver, and among family members. This psychometric investigation was designed to further examine the reliability and validity of the revised Caregiver Reciprocity Scale II (CRS II). Items were rewritten to reflect valued exchanges and balance among the entire family network, including spouses. An alpha of .83 for Warmth and Regard; .73 for Intrinsic Rewards of Giving; .83 for Love and Affection; and .75 for Balance Within Family Caregiving indicated acceptable internal consistency. The study, conducted with 176 spouse or adult children caregivers, provides additional support for the conceptual model of the four-factor solution. Construct validity was supported by the standardized factor loadings and goodness-of-fit indices obtained from confirmatory factor analysis. The results of the analysis of the measurement model, taken as a whole, demonstrate that the CRS II has adequate psychometric properties. Model parsimony was supported by an AGFI of .87, combined with an adjusted chi-square between 1.0 to 3.0. All but two item loadings were greater than .50. This, combined with the fact that all standardized loadings were twice the standardized errors and t-values were greater than 2.0, contributes to concluding that convergent validity was strong. Discriminant validity, evaluated by variance extracted estimates, and confidence interval (+/- two standard errors) around the correlation estimate between factors, was adequate. This study provided evidence to support the reliability and validity of the CRS II.

Adult↗
PubMedDate not supplied

A device for evaluation of flow recording equipment.

We have constructed a calibration device which simulates a maximum expiratory flow, and which can also be used to determine quantitatively the frequency response and linearity of flow recording equipment. It consists of a pressure chamber full of copper chips serving as a heat exchanger. When inflated to twice the atmospheric pressure, it delivers 8.2 l of air during deflation. Deflation is released by a falling weight. The time tS between 10% and 90% of the peak expiratory flow out of the chamber (PEFR) can be varied between 10 ms and 90 ms. PEFR up to 19 l X s-1 can be obtained by changing the size of an orifice in the outlet line. The calibrator was tested with a Fleisch no 4 pneumotachograph linear up to 15 l X s-1. The coefficient of variation of PEFR (12.2 l X s-1) and FVC (8.2 l) was 2% and 1% respectively for 10 consecutive deflations. The frequency response in terms of tS of the tested equipment can be evaluated from the flow-volume curve produced by the calibrator. Examination of tS in 50 medical students shows that tS of the equipment should be less than about 20 ms in order to correctly measure PEFR. By means of a single deflation, the linearity of the total recording system can be tested over a range of flows because the flow signal of the calibrator is declining almost linearly with time.

Forced Expiratory Flow Rates↗