The existence of a second route for the transfer of certain glycoproteins from the circulation into the liver.

Oligosaccharide chains of agalactoorosomucoid, α₁-acid glycoprotein from which sialic acid and galactose have been sequentially removed, terminate in N-acetylglucosaminyl residues. This protein is rapidly transferred from the circulation into the liver by a route distinct from that previously demonstrated for a number of galactosyl terminating glycoproteins.     

Neurohormonal Integration of Osmotic and Ionic Regulation

There is evidence in crustaceans that neuroendocrine centers,including the eyestalk, brain, thoracic ganglionic mass, andpericardial organ, produce factors that affect osmotic and ionicregulation. Understanding of the processes responsible for osmoticadjustment in the intact animal, such as regulation of permeability,active uptake of ions, and respiratory and cardiovascular alterations,has increased substantially in the past few years. However,interaction of neuroendocrine factors with the target tissuesand systems is just beginning to be investigated. There is evidencethat content of lipids and activity of enzymes are importantin osmoregulation, and neuroendocrine effects on these metabolicprocesses are worthy of study. In addition, there are some crustaceansin which osmoregulatory ability varies developmentally. Furtherinvestigations of such animals is also necessary. Progress inour understanding of neuroendocrine influences on osmoregulationdepends upon further purification of active factors from neuroendocrinecenters and hemolymph, and upon development of appropriate assayson which to test them.     

Adenosine binding sites of rat pheochromocytoma PC 12 cell membranes: partial characterization and solubilization

Rat pheochromocytoma PC 12 cell membranes were shown to possess A2-like adenosine binding sites as assessed by using 5'-N-ethylcarboxamide[3H]adenosine [( 3H]NECA). Specific [3H]NECA binding to PC 12 cell membrane at 0 degrees C was saturable and showed a monophasic saturation profile. In contrast, [3H]NECA binding to PC 12 cell membrane at 30 degrees C exhibited a biphasic profile suggesting the presence of two specific binding site. The rank order of potency for inhibition of [3H]NECA binding at 0 degrees C was NECA greater than 2-chloroadenosine greater than 2',5'-dideoxyadenosine greater than isobutylmethylxanthine much greater than phenylisopropyladenosine. These adenosine binding sites were solubilized with sodium cholate and the solubilized portion retained the same ligand binding characteristics as those of the membrane-bound form. Gel filtration experiments indicated an apparent Stokes radius of 6.7 nm for these adenosine binding sites/detergent complexes.     

Fine structure of early human embryos frozen with 1,2 propanediol

Previous studies by a French group (Fertil Steril 44:645–651, 1985) have shown that two-to eight-cell human embryos can survive slow freeze-thawing with propanediol in a biological freezer. These embryos were assessed for morphological appearance by phase-contrast microscopy. We assessed the structure of 25 frozen-thawed one- to 12-cell embryos, obtained from our in vitro fertilization (IVF) and GIFT programmes, by phase-contrast and electron microscopy, using the same method of cryopreservation. One-fourth of the embryos examined had all cells intact, and more than one-half the embryos had over 50% of their cells well preserved. Some of these embryos had unequal blastomeres and cytoplasmic fragments. Ultrastructural assessment revealed good preservation of fine structure in the intact blastomeres of all embryos and maintenance of cell-to-cell contacts. Most cytoplasmic organelles, cell membranes, and nuclei were well preserved compared to nonfrozen controls. The cells that were cryoinjured showed varying degrees of disorganization of the cell membrane, cytosol, and cellular membranes, including swelling and disruption of the nuclear envelope. Disruption of the zona was somewhat rare. Small cytoplasmic fragments were less prone to cryoinjury than blastomeres. The use of propanediol for embryo cryopreservation seems to be feasible; frozen embryos with more than 50% cells intact have produced 10 pregnancies after embryo transfer (Fertil Steril 46:268–272, 1986). Replacement of 17 frozen embryos in seven patients has resulted in a twin pregnancy in Singapore. However, the effects of freezing on the mitotic spindles of embryonic cells need to be investigated further.     

The determination of purine levels in human and mouse plasma

Variable levels of acetic anhydride have been recommended for addition to one of two reagents used in the glyoxylic acid method for the determination of tryptophan. For use of this reagent immediately after preparation it was shown that a minimum of 16% (v/v) of acetic anhydride should be included in the formulation to obtain near-maximum sensitivity. It was further demonstrated that reagent formulations with and without acetic anhydride changed with exposure to light. The observed changes are manifest as changes in the relative sensitivities of the assay. Several modifications are recommended to improve the sensitivity and stability of the acetic anhydride-containing reagent in this assay.     

Muscle and femoral vein temperatures during short-term maximal exercise in heart failure

Core temperature decreases throughout short-term maximal exercise in heart-failure patients. To investigate possible causes for this unusual response to exercise, we studied core (pulmonary arterial blood), femoral vein, muscle, and skin temperatures in eight patients with severe heart failure who performed maximal upright incremental bicycle exercise to 50 W. A normal group (n = 4) was exercised for comparison. In the heart-failure patients, core temperature was 36.95 +/- 0.37 degrees C at rest, significantly (P less than 0.05) decreased at 25 W of exercise to 36.59 +/- 0.40 degrees C, and at 50 W remained decreased to 36.57 +/- 0.40 degrees C. In comparison, we found that the resting core temperature in the normal subjects was 37.28 +/- 0.34 degrees C, was the same at 25 W (37.29 +/- 0.41 degrees C), and increased significantly (P less than 0.05) to 37.50 +/- 0.32 degrees C at 50 W of exercise. Femoral vein temperature in heart-failure patients (n = 6) was below core temperature throughout exercise to 25 and 50 W (36.22 +/- 0.62 and 36.34 +/- 0.65 degrees C, respectively). Muscle temperature (n = 7) was significantly (P less than 0.05) lower in the heart-failure patients (34.8 +/- 1.1 degrees C) at rest compared with the normal subjects (36.2 +/- 1.0 degrees C). During exercise, muscle temperature increased above core temperature in only four of the heart-failure patients and was significantly (P less than 0.05) lower (36.5 +/- 1.3 degrees C) compared with the normal subjects (38.0 +/- 0.2 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)     

Differences in membrane lipid composition and fluidity of transplanted GRSL lymphoma cells, depending on their site of growth in the mouse

GRSL lymphoma cells were isolated from various growth sites in the host. The relative membrane lipid fluidities of these cells and of normal lymphoid cells were estimated by fluorescence polarization, using the probe diphenylhexatriene and by measuring the (free) cholesterol/phospholipid molar ratio in whole cells. The results indicate that the membrane fluidity (reciprocal of the lipid structural order) of the lymphoma cells increases in the order of their location: peripheral blood less than spleen less than mesenterial lymph node less than ascites fluid. The membrane fluidities of normal lymphocytes from thymus, mesenterial lymph node and spleen were about the same, but higher than of peripheral blood lymphocytes, and between those of the lymphoma cells from lymph node and spleen. These results are confirmed by more extensive analysis on purified plasma membranes from the splenic and ascitic GRSL lymphoma cells and from normal splenocytes and thymocytes. The significantly higher lipid order parameter found in the GRSL plasma membrane isolated from the spleen as compared to those from the ascites cells could be fully explained by the differences measured in the major chemical determinants of the fluidity, i.e., the cholesterol/phospholipid ratio, the sphingomyelin content and the degree of saturation of the fatty acyl groups of the phospholipids. It was also found that the cholesterol/phospholipid ratio in erythrocyte membranes isolated from the peripheral blood of the tumor bearers was higher than in those from normal control mice. The observed differences in membrane fluidity between distinct subsets of tumor cells may be relevant to the sensitivity of these cells to immune attack or to drugs.