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Biomedical subjects

J A Jimenez

Publications and source records attributed to J A Jimenez.

9 recordsLinked to original sources
PubMed2002

MELFI.

The Minus Eighty degree celsius Laboratory Freezer for ISS (MELFI) is a rack-sized facility that will provide the Space Station with a refrigerated volume for the storage and fast freezing of life-science and biological samples. It will also ensure the safe transportation of conditioned specimens to and from the ISS by flying in fully powered mode in the Multi-Purpose Logistic Module (MPLM) installed in the Shuttle's cargo bay. Continuous operation for up to 24 months is foreseen for each MELFI mission.

Cold Temperature↗
PubMed2001

Azole-linked coumarin dyes as fluorescence probes of domain-forming polymers.

The binding of 7-aminocoumarins, substituted in the 3-position with heterocyclic benzimidazole or benzothiazole groups by domain-forming polymers in water has been studied. The acrylic polyelectrolyte, poly(methacrylic) acid (PMAA) was used as a solubilizing agent for coumarin dyes 6, 7, and 30 in water. The acid-base properties of these bound coumarin dyes were monitored spectroscopically on titration of aqueous solutions. Alterations in the fluorescence wavelength and intensity, quantum yields, lifetimes, and polarization are consistent with the preferential binding of the dyes in compact hydrophobic domains that form at a pH regime in which the polymer is in its protonated (uncharged) state. In this pH range (<4.0), coumarins 7 and 30 are bound as monocations, whereas coumarin 6 remains in its neutral form. Reduced quantum yields and lifetimes of fluorescence for cationic coumarins can be understood in terms of the imposition of a low-lying electron transfer state, an example of a twisted intramolecular charge transfer (TICT) intermediate. Effects of polymer microenvironment on the rate of TICT state decay (a reverse electron transfer) are observed. Coumarins of the azole type may find use as fluoroprobes of the microenvironments of proteins and other biological macromolecules and as agents for pH sensing.

Benzimidazoles↗
PubMed1995

Effects of calcium soaps of fatty acids on postpartum reproductive activity in beef cows and growth of calves.

Beef cows were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics and growth of calves. Cows were assigned randomly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets were isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7-d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P < .05; 56.0 vs 50.6 kg, P< .01; 98.8 vs 91.8 kg, P < .01; and 186 vs 173 kg, P < .01, respectively). Body weights at 35 and 50 d postcalving were greater in M than in C cows (334 and 310 kg, P < .01; 329 and 300 kg, P < .01, respectively). A similar tendency was observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P < .01 for M and C, respectively). Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides were greater (P < .01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P < .02). Percentage of pregnant cows during the first half of the breeding season was greater (P < .02) in M (62.5%) than in C cows (35.5%). We concluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calves.

Aging↗
PubMed1994

Effects of glucose, ethanol, Hg(II) and Cu(II) on almond beta-glucosidase.

The kinetic parameters of almond beta-glucosidase (beta-D-glucoside glucohydrolase; EC 3.2.1.21), using pNGP as substrate were kM = 2.24 +/- 0.11 mM and Vmax 588 +/- 25.1 U/mg protein. Only Hg(II) and Cu(II) showed irreversible inactivation of the enzyme. However, when these metals were present in the reaction system the inhibition effects were consistent with a mixed-type inhibition pattern (Cu(II) ki: 5.08 mM and Hg(II) ki: 0.07 mM). The glucose kinetic effect was also consistent with a mixed-type inhibition (ki = 406 mM) pattern with pNGP as varied substrate. Ethanol displayed the kinetic pattern of competitive inhibition (ki = 640 mM).

Amino Acid Sequence↗
PubMed1989

Vitamin D status of elderly people in Spain.

Serum levels of 25-hydroxyvitamin D (25OHD3), 1, 25-dihydroxyvitamin D [1, 25-(OH)2D3], PTH and osteocalcin were measured in 114 subjects living in the South of Spain (Cordoba, latitude 37.6 degrees) during early spring. Results in young healthy adults (group G1) were compared with values found in three groups of elderly subjects (mean age 77 years): healthy elderly people living at home (G2), or in a residence (G3) and chronically sick and hospitalized elderly patients (G4). Mean serum 25OHD3 was lower in the elderly groups G2 and G3 than in young adults but the lowest values were found in G4. The opposite trend was found for serum PTH. Mean serum 1,25-(OH)2D3 levels were similar in G2 and G3 to G1 but were significantly lower in G4. In a sunny country only chronically sick and hospitalized elderly patients have very low 25OHD3 levels and fail to maintain normal 1,25-(OH)2D3 concentrations despite secondary hyperparathyroidism.

Adult↗