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F Engelmann

Publications and source records attributed to F Engelmann.

At least 19 recordsLinked to original sources
PubMed2005

Optimal hydration status for cryopreservation of intermediate oily seeds: Citrus as a case study.

BACKGROUND AND AIMS: The purpose of this study was to investigate the basis of the optimal hydration status for cryopreservation of intermediate oily seeds using Citrus as a model. METHODS: The relationships between equilibrium relative humidity (RH), seed water content, presence of freezable water as determined by DSC analysis, and germination percentage after immersion in liquid nitrogen (LN) were investigated in Citrus aurantifolia, C. grandis, C. madurensis and C. reticulata. The relationship between the lipid content of seeds and their unfrozen water content was also investigated. KEY RESULTS: Independent of their level of seed desiccation tolerance, the optimal desiccation RH for seed tolerance to LN exposure was 75-80 % in the four species studied. This optimal hydration status always coincided with that at which presence of frozen water could not be detected in seed tissues during the cooling/thawing process. The unfrozen water content of seeds was variable between species and negatively correlated to seed lipid content. Using the present data, those obtained previously in seven coffee species and those reported by other authors for five other species, a significant linear relationship was found between the lipid content and the unfrozen water content of seeds. CONCLUSIONS: This study provides additional evidence that intermediate oily seeds do not withstand the presence of freezable water in their tissues during the cooling/warming process. Moreover, it offers two important applied perspectives: (1) independent of their level of desiccation tolerance, testing germination of seeds of a given oily seed species after equilibration in 75-80 % RH at 25 degrees C and LN exposure, gives a rapid and reliable evaluation of the possibility of cryopreserving whole seeds of this given species; (2) it is now possible to calculate the interval of water contents in which non-orthodox oily seeds of a given species are likely to withstand LN exposure as a function of their lipid content.

Citrus↗
PubMed1998

Effects of the type-1 Na+/H+-exchange inhibitor cariporide (Hoe 642) on cardiac tissue.

Ischemia leads to intracellular acidification which can be counteracted by the Na+/H+-exchange mechanism. A blockade of this exchanger has been hypothesized to cause stronger intracellular acidification in the course of ischemia thereby protecting the heart from ischemic damage. The aim of our study was to find out (1) whether in the course of ischemia areas become electrically silent, (2) whether this is enhanced by the Na+/H+-exchange inhibitor cariporide (4-Isopropyl-3-methylsulfonylbenzoyl-guanidine; Hoe 642) and whether cariporide has protective effects. Therefore, we submitted isolated rabbit hearts, perfused according to the Langendorff technique to regional ischemia (LAD occlusion) for 30 min followed by 30 min reperfusion with (n=7) or without (n=7) pre-treatment with 1 microM cariporide. Under these conditions 256-channel epicardial potential mapping was carried out. Under non-ischemic conditions cariporide did not alter any of the parameters under observation. We found that ischemia led to marked alterations of the activation pattern, to action potential shortening and a marked increase in the dispersion of refractoriness. In the ischemic region there was a significant ST deviation from the isoelectrical line (control 32+/-10; 30 min ischemia: 290+/-35 arbitrary units [a.u.]). This was markedly reduced by cariporide (control 39+/-10; 30 min ischemia: 170+/-25 a.u.). The increase in dispersion by ischemia (by 50+/-5 ms) was significantly counteracted by cariporide (increased dispersion by 20+/-4 ms). In a similar way the alteration of the activation pattern was antagonized. Under the influence of cariporide we found a lower increase in the left ventricular enddiastolic pressure, and a significantly slower recovery of the action potential duration. After 30 min of ischemia 24+/-5 (control series) 24.5+/-5 mm2 (cariporide) became electrically silent. In a second series of experiments the incidence of arrhythmia was assessed: we found ventricular fibrillation in 6/7 untreated control hearts and in 4/7 cariporide treated hearts. In a third series of experiments we determined the intracellular [ATP] after 30 min of LAD occlusion using a histochemical method. We observed a decrease in [ATP] in the ischemic region as compared to the non-ischemic right ventricular wall, which was less pronounced in cariporide-treated hearts. Thus, we conclude that (1) cariporide protects the heart from ischemic damage and (2) at least under these conditions an enlargement of the electrically silent area did not occur.

Action Potentials↗
PubMed1997

The biosynthesis and processing of vitellogenin in the fat bodies of females and males of the cockroach Leucophaea maderae.

The juvenile hormone analog (JHA) methoprene was used to induce the synthesis of the yolk protein precursor vitellogenin (Vg) in adult females and males of the cockroach Leucophaea maderae. The female- and male-produced vitellogenin (VgF and VgM, respectively) contained polypeptides of 112, 95, 92, and 54 kDa. Also present in the secreted vitellogenins was a soffmall quantity of a short-lived transitional 155 kDa Vg polypeptide, and a variable amount of an 85 dDa species. Quantitatively, the VgF and VgM were significantly different in the Vg112 and Vg95 units (VgF > VgM), and in the Vg85 polypeptide (VgF < VgM). In the present study, the biosynthesis of Vg precursors in the fat bodies of females and males was examined using a short radiopulse with 35S-methionine/cysteine and 32P-orthophosphate. The glycosylation of the Vg precursors was examined by digestion with endoglycosidase H and by the inhibition of N-linked glycosylation with tunicamycin. The data showed that in both females and males, the synthesis of the vitellogenin precursor occurred in a stepwise fashion: (1) the co-translational glycosylation of Vg203; (2) the post-translational phosphorylation of Vg203 to form Vg220; (3) the proteolytic processing of Vg220 to form the constituent Vg polypeptides. The 203 and 220 kDa Vg precursors of females and males appeared to be similarly glycosylated and phosphorylated. The additional processing of Vg112 to Vg85 was more pronounced in the fat bodies of males than in females, and appears to account for the quantitative difference in the distribution of these polypeptides in VgF and VgM. Finally, the major oligosaccharides of VgF and VgM appear to be those of N-linked mannose residues. The treatment of females and males with tunicamycin indicated that the co-translational glycosylation of Vg precursors was required for the phosphorylation of the Vg precursor, as well as the secretion of Vg from the fat body.

Adipose Tissue↗
PubMed1995

The juvenile hormone receptor of the cockroach Leucophaea maderae.

The juvenile hormone (JH) receptor has been isolated and purified from fat bodies of females and males of Leucophaea maderae. The sequence of procedures that yielded an apparently pure compound involved ammonium sulfate precipitation (20-60% saturation cut), DEAE anion exchange column chromatography, and polyacrylamide gel electrophoresis. The molecular size of the resulting high affinity JH-binding protein is about 64 kDa and is apparently composed of two equal subunits of 32 kDa. A polyclonal antibody has been produced against this molecule and used for the construction of an immunoaffinity column. A pure JH receptor molecule has been isolated from crude fat body homogenates with this affinity column. The JH receptor is first identified in last instar nymphs and quantitatively increases as the instar progresses towards adult development. In penultimate nymphal instars this JH receptor could not be identified and this is correlated with a lack of competence to make vitellogenin (Vg) upon exposure to the JH analog methoprene. Thus, a correlation is seen between the presence of the JH receptor and the competence to synthesize Vg.

Animals↗
PubMed1986

[An alternative to the hospitalization of the demented elderly: the nursing home].

The number of demented old people continues to increase. Their admission to a hospital is dangerous ("Syndrome de Glissement") and tolerated with difficulty by the nursing staff. The solution of home care is interesting but insufficient. The creation of collective homes for demented elderly seems to furnish an effective solution contributing to a decrease in hospital admissions and a better quality of life for these persons. The modalities of creation and functioning are considered and allows one to think that these establishments will appear in France and also, in the world.

Aged↗
PubMed1981

Heterogeneity of juvenile hormone binding compounds in fat bodies of a cockroach.

Fat bodies of adult vitellogenic or non-vitellogenic females and those of adult males contain 2 populations of saturable JH binding compounds. The respective Kd vales are 2-5 x 10(-9) M and 1-4 x 10(-8) M. Fat bodies of penultimate nymphs, hemolymph of any animal, and midgut epithelia contain one saturable JH binder with a Kd of 1-5 x 10(-8) M. Unlabeled JH I and III, as well as the JH analog ZR-515 compete effectively for the binding sites in these tissues. The 2 classes of hormone binders were separated by DEAE ion-exchange column chromatography. The very high affinity molecules of the adult fat bodies are presumably the specific JH receptors which may function in translocation of the hormone to the nucleus. The compound with relatively lower hormone affinity may be the JH hemolymph carrier which is also produced by the fat bodies and then exported.

Adipose Tissue↗
PubMed1976

[Pregnancy type nephropathies experimentally induced in rats].

The theory behind our work is the following: toxaemia may be due to the accidental passage of fetal proteins into the maternal organism. Particularly suspect are alpha-fetoproteins from the fetal blood or the amniotic fluid. The experiments were carried out on rats by injecting amniotic fluid or fetal serum into the rats by different routes and rhythms and in different doses. Arterial blood pressure readings showed that the levels were consistently higher than those of controls. The study of the kidneys anatomo-pathologically shows the following triad: intense congestion, tubular lesions, connective tissues affected. These lesions are reversible. The discussion concentrates on the similarities and differences between these findings and pathological changes found in kidneys in pregnancy.

Amniotic Fluid↗
PubMed1972

Etude des constantes de liaison entre les oestrogenes et 1'alpha(1)-foetoproteine de rat.

The binding constants of the alpha(1)-foetoprotein of the rat embryo serum for oestrone and oestradiol-17beta have similar values, i.e. 1 x 10(8) M(-1) in average at 25 degrees. There is probably one binding site per mole of binding protein. The high alpha(1)-foetoprotein concentration in the rat embryo serum at 17-19 days of pregnancy explains the exceptionally high levels of fixation of the phenolsteroids by this serum.

Journal Article↗