Chest-wall deformity after tissue expansion for breast reconstruction

A prospective longitudinal study of chest-wall deformity after tissue expansion for breast reconstruction was performed in 19 women. CT imaging was a sensitive method for detecting occult deformity. Using a semiquantitative scale for measuring deformity, all patients and 94 percent of expanders had some thoracic abnormality after tissue expansion. Rib and chest-wall contour changes were observed under 81 and 68 percent of the expanders, respectively. Routine chest roentgenograms were not a sensitive method for evaluating these deformities. The magnitude of deformity after unilateral expansion was not significantly different from that after bilateral expansion. Linear regression analysis indicated that early periprosthetic capsular contracture was negatively correlated with chest wall deformity. Only one patient experienced a clinically noticeable complication from chest compression--transient postexpansion exertional dyspnea. After removing the expanders and placing permanent implants along with capsulotomy, the mean deformity index decreased by 57 percent after 10.5 months median follow-up, which was highly significant (p less than 0.001). Our findings suggest that chest-wall deformity is a common occurrence after tissue expansion in patients undergoing breast reconstruction and is usually of minor clinical significance.     

Region-specific differentiation of the hippocampal stem cell line HiB5 upon implantation into the developing mammalian brain

Proliferating precursors to the distinct cell types constituting the mammalian brain can be identified by the presence of the nestin intermediate filament. We report the establishment of a nestin-positive cell line, HiB5, from embryonic precursor cells to the rat hippocampus. Since it was immortalized using the temperature-sensitive allele tsA58 of SV40 large T antigen, these cells grow continuously at 33 degrees C, but not at 39 degrees C, the body temperature of rodents. To test their developmental capacity, HiB5 cells were implanted into both the neonatal hippocampus and cerebellum. The cells integrated into the host tissue and acquired morphologies characteristic of the neurons and glial cells found at the implant site. HiB5 cells might thus be useful in characterizing the signals regulating cell type determination in the mammalian brain.     

The cellular and molecular regulation of 1,25(OH)2D3 production

The synthesis of 1,25(OH)₂D₃ is a critical control point in the regulation of calcium metabolism, and possibly in the growth and differentiation of a number of cell types. This paper reviews our current understanding of the regulation of this process at the cellular and molecular levels, with the emphasis on the mechanisms of feedback control 1,25(OH)₂D₃ itself, control of parathyroid hormone, the roles of cyclic AMP dependent protein kinase and protein kinase C, and the interaction between the various intracellular regulators of 1,25(OH)₂D₃ production.     

Nutritional value of palm wine fromHyphaene coriacea andPhoenix reclinata (Arecaceae)

Palm wine is an alcoholic beverage consumed by rural people in Maputaland, Natal, South Africa. Nutritional information on the nutrient content of palm wine fromHyphaene coriacea andPhoenix reclinata was obtained in order to provide more detailed nutritional data than were previously available. The results showed that while palm wine is an important source of nicotinic acid and vitamin C, previous studies appear to have overestimated its value as a source of protein, thiamin, and riboflavin.     

Purification of a form of protease nexin 1 that binds heparin with a low affinity

A form of protease nexin 1 (PN-1) that binds heparin with a low affinity (L-PN-1) was purified and studies since altered interactions with glycosaminoglycans could affect its inhibition of certain serine proteases. Purification of L-PN-1 and PN-1 was achieved by fractionating serum-free conditioned culture medium from human fibroblasts over dextran sulfate-Sepharose followed by immunoaffinity fractionation over a PN-1 monoclonal antibody-Sepharose column. The first step separated L-PN-1 from PN-1, and the second step resulted in apparently homogeneous L-PN-1 and PN-1. Comparisons of the two proteins showed that they could not be distinguished by the following properties: (a) molecular weight; (b) proteases complexed; (c) molecular weights of protease-L-PN-1 and protease-PN-1 complexes; (d) CNBr peptide maps; and (e) immunological cross-reactivity. Studies on activities that depend on the heparin binding domain revealed that heparin equally accelerated the rate of formation of 125I-thrombin-L-PN-1 and 125I-thrombin-PN-1 complexes even when the ratio of heparin to L-PN-1 or PN-1 was varied from 0.01 to 100. A functional difference, however, between L-PN-1 and PN-1 was observed in studies on the ability of the fibroblast surface to accelerate their reactions. Fixed fibroblasts accelerated the formation of 125I-thrombin-L-PN-1 complexes 2-fold, whereas they accelerated the formation of 125I-thrombin-PN-1 complexes 5-fold. The availability of purified L-PN-1 will permit studies on its functional relationship to PN-1.     

Isolation and identification of seven metabolites of 25-hydroxydihydrotachysterol3 formed in the isolated perfused rat kidney: a model for the study of side-chain metabolism of vitamin D

The in vivo metabolism of dihydrotachysterol3, an analogue of vitamin D3 and a potent calcemic factor, has been studied in the rat. This in vivo metabolism is compared to the in vitro metabolism of 25-hydroxydihydrotachysterol3 in the perfused rat kidney. Using mass spectrometry and ultraviolet spectroscopy, we have identified seven novel metabolites derived from 25-hydroxydihydrotachysterol3. The seven compounds represent intermediates on two renal pathways (24-oxidation and 26,23-lactone formation) also observed for 25-hydroxyvitamin D3. No evidence was found for the renal synthesis of a 1-hydroxylated metabolite of 25-hydroxydihydrotachysterol3 analogous to the hormone 1,25-dihydroxyvitamin D3. Two of the compounds formed in vitro, 24,25-dihydroxydihydrotachysterol3 and 25-hydroxydihydrotachysterol 26,23-lactone, were also formed in vivo. In vivo studies also revealed the formation of two other unidentified metabolites which are presumed to be formed nonrenally and may be calcemic factors. This work shows that dihydrotachysterol3 metabolism is complex and probably utilizes the same side-chain enzymes as vitamin D3. In addition, our work also confirms that intermediates postulated to lie on pathways to 26,23-lactone in the vitamin D3 series are also formed for the side chain in dihydrotachysterol3.     

Monovalent ion-phosphatidylcholine interactions: an electron paramagnetic resonance study

The apparent Mn2+ binding constant for L-alpha-dipalmitoylphosphatidylcholine (DPPC) bilayers dispersed in monovalent salt and MnCl2 dispersions was determined as a function temperature using electron paramagnetic resonance (ERP). Reproducibility in the data sets requires the use of a standard salt solution and dual cavity techniques. Changes in the binding constant at different phase states and temperatures were observed and correlated to the influence of monovalent salts on the thermal properties of DPPC. The turning points (i.e. changes in slope) in the curves of the apparent Mn2+ binding constant versus temperature can be understood in terms of differences in ion binding to headgroups with different bilayer surface areas. The influence of Li+ and SCN- on Mn2+ binding is viewed as a function of their presence in the ionic media in contact with the bilayer rather than as a competitive event. Other monovalent ions studied appear to have little effect on the measured apparent Mn2+ binding constants for DPPC headgroups.     

Thiocyanate and bromide ions influence the bilayer structural parameters of phosphatidylcholine bilayers

The influence of monovalent cations and anions on the structural parameters of dipalmitoylphosphatidylcholine (DPPC) bilayers was examined at 25 degrees C using X-ray diffraction. It was shown that monovalent salts, in general, have little effect on lipid packing within the bilayer. However, fully hydrated DPPC bilayers in 1 M KSCN pack in an interdigitated acyl chain phase. This is the first observation of an ion-induced interdigitated bilayer phase in a zwitterionic lipid. In addition, gel state DPPC bilayers in 1 M KBr imbibe approx. 10 A more solvent than bilayers in water. The influence of these same salts on the phase transitions of DPPC bilayers was also examined using high-resolution differential scanning calorimetry. These results are discussed in terms of ion-induced changes in solvent and solvent/bilayer structure.     

Effect of fasting and acute ethanol administration on the energy state of in vivo liver as measured by 31P-NMR spectroscopy

The effects of 48 h fasting, administration of ethanol or 2,4-dinitrophenol, on the phosphorus-containing metabolites in liver in vivo have been determined utilizing 31P nuclear magnetic resonance spectroscopy. These measurements were combined with determinations of metabolite concentrations in livers which were freeze-clamped immediately after the NMR measurements were completed. Administration of sub-lethal amounts of dinitrophenol dramatically decreased ATP and increased Pi concentrations in liver in vivo as indicated by a 2.7-fold increase in the NMR-derived [Pi]/[ATP] ratio. Ethanol administration to fed animals increased the NMR-derived [Pi]/[ATP] ratio 27%; in contrast, the same amount of ethanol administered to fasted animals decreased the NMR-derived [Pi]/[ATP] ratio 30%. The NMR visible Pi and ADP represent about 50% and 15% of the total Pi and ADP, respectively. The phosphorylation potentials calculated from the NMR visible Pi and ADP were an order of magnitude higher than those obtained from metabolite concentrations in freeze-clamped tissue. There was no apparent correlation between the phosphorylation potentials derived from either the NMR spectral analyses or from metabolite concentrations and the hepatic [NAD+]/[NADH] ratio. The chemical shift of Pi indicated that ethanol administration elicited a decrease in pH of 0.1 unit in liver in vivo. Hepatic free [Mg2+] was increased 21% in fasted animals, but was unaffected by ethanol administration.