Biomedical subjects

L M Mulfinger

Publications and source records attributed to L M Mulfinger.

5 recordsLinked to original sources

PubMed2000

Stair negotiation in older people: a review.

Locomotion on stairs is among the most challenging and hazardous activities of daily living for older individuals. This is evidenced by the reports that stair falls account for more than 10% of fatal fall accidents. The demands that stairs place on the musculoskeletal and cardiovascular systems are compounded by the need for input from the somatosensory, visual, and vestibular systems at various stages in the task. Many of these collaborating systems deteriorate with aging, thus increasing the difficulty and risk of failure in a task that inherently involves exposure to significant danger. The task itself varies in its degree of challenge depending on many structural and environmental factors that are outside the control of the stair user. This review explores existing literature in the area of stair negotiation by older persons in an effort to define the key factors associated with difficulty and safety on stairs and to interpret these findings in the light of possible interventions that could increase stair safety. Further research is needed to ensure that current recommendations for stair design are suitable for older stair users. A Glossary of Terms is also provided.

Accidental Falls↗

PubMed1997

How do the elderly negotiate stairs?

Stair navigation, particularly stair descent, is an extremely challenging and dangerous locomotor task, yet studies suggest that most elderly are unlikely to move to new residences in order to avoid this challenge. The knee and ankle are the key joints where adequate strength and power are required for safe stair descent, and it is not yet clear if sarcopenia in the elderly is likely to result in residual strength below that which is required for successful stair performance. Sensory cues are also critical, and the lack of literature on the specific roles of the various intrinsic and extrinsic factors that affect stair navigation is a clear indication of the need for such research in order to define safer strategies and optimal conditions for elderly individuals to transit between living areas of differing levels.

Aged↗

PubMed1987

Purification and properties of formylglutamate amidohydrolase from Pseudomonas putida.

Formylglutamate amidohydrolase (FGase) catalyzes the terminal reaction in the five-step pathway for histidine utilization in Pseudomonas putida. By this action, N-formyl-L-glutamate (FG) is hydrolyzed to produce L-glutamate plus formate. Urocanate, the first product in the pathway, induced all five enzymes, but FG was able to induce FGase alone, although less efficiently than urocanate did. This induction by FG resulted in the formation of an FGase with electrophoretic mobility identical to that of the FGase induced by urocanate. A 9.6-kilobase-pair HindIII DNA fragment containing the P. putida FGase gene was cloned into the corresponding site on plasmid pBEU1 maintained in Escherichia coli. Insertion of the fragment in either orientation on the vector resulted in expression, but a higher level was noted in one direction, suggesting that the FGase gene can be expressed from either of two vector promoters with different efficiencies or from a single vector promoter in addition to a less efficient Pseudomonas promoter. FGase was purified 1,110-fold from the higher-expression clone in a yield of 10% through six steps. Divalent metal ions stimulated activity, and among those tested (Co, Fe, Zn, Ca, Ni, Cd, Mn, and Mg), Co(II) was the best activator, followed by Fe(II). FGase exhibited a Km of 14 mM for FG and a specific activity of 100 mumol/min per mg of protein in the presence of 5 mM substrate and 0.8 mM CoCl2 at 30 degrees C. The enzyme was maximally active in the range of pH 7 to 8. FGase was found to be a monomer of molecular weight 50,000. N-Acetyl-L-glutamate was not a substrate for the enzyme, but both it and N-formyl-L-aspartate were competitive inhibitors of formylglutamate hydrolysis, exhibiting Ki values of 6 and 9 mM, respectively. The absence of FGase activity as an integral part of histidine breakdown in most other organisms and the somewhat uncoordinated regulation of FGase synthesis with that of the other hut enzymes in Pseudomonas suggest that the gene encoding its synthesis may have evolved separately from the remaining hut genes.

Amidohydrolases↗

PubMed1986

A qualitative and quantitative analysis of proteins found in vespid venoms.

Diagnosis and immunotherapy with venom extracts of patients sensitive to Hymenoptera stings has led to the problem of improving the standardization of Hymenoptera venom products. Current methods of standardization use the Lowry protein determination and a radial-diffusion assay for hyaluronidase activity. This study demonstrates that the results of these analyses do not always correlate with the actual quantity of allergenic protein present in the extracts. A method of standardization is examined herein that uses polyacrylamide gel electrophoresis to quantitate phospholipase A, antigen 5, and hyaluronidase, the proteins that together comprise most allergenic protein present in the venoms. Also discussed in this study is the biochemical variability of phospholipase A and antigen 5 in the venoms of the different vespid species examined.

Bee Venoms↗

PubMed1981

Cyclic adenosine 3',5'-monophosphate levels in Pseudomonas putida and Pseudomonas aeruginosa during induction and carbon catabolite repression of histidase synthesis.

Inducibility of histidase (histidine ammonia-lyase, EC 4.3.1.3) in Pseudomonas putida and Pseudomonas aeruginosa was observed to be strongly affected by succinate-provoked catabolite repression, but this did not occur as a consequence of reduced intracellular cyclic adenosine 3',5'-monophosphate levels, and repression could not be alleviated by exogenously added cyclic adenosine 3,'5'-monophosphate. Milder repression of histidase by lactate was also not reversed by the addition of cyclic adenosine 3',5'-monophosphate. These results, along with data showing intracellular cyclic adenosine 3',5'-monophosphate levels remained essentially constant during growth on such diverse carbon sources as histidine, acetamide, glucose, and succinate, indicated that catabolite repression of histidase synthesis by efficient carbon sources was not mediated through variations in internal cyclic adenosine 3,'5'-monophosphate.

Ammonia-Lyases↗