Evaluation of the radiologic findings on hysterosalpingography by selective hydrotubation with flexible hysterofiberscope

In order to assess the influence of the protein charge on its partitioning in poly(ethyleneglycol)/salt aqueous two-phase systems, three bovine serum albumin derivatives with isoelectric points of 5.50, 6.20 and 6.85 were obtained by chemical modification of the protein with a soluble carbodiimide and glycine O-methyl ester and separation of the derivative mixture by liquid isoelectric focusing. The modification reaction was mild enough to preserve the tertiary structure of the proteins, as judged by circular dichroism and fourth derivative UV spectra. The surface hydrophobicity of the bovine serum albumin derivatives was identical, as measured by hydrophobic interaction chromatography. Partitioning of the derivatives in poly(ethyleneglycol)/phosphate and poly(ethyleneglycol)/citrate aqueous two-phase systems between pH 5.2 and 6.5 indicates that partitioning is not dependent on the protein charge in the poly(ethyleneglycol)/salt systems studied.     

Resection of residual retroperitoneal masses in testicular cancer: evaluation and improvement of selection criteria. The ReHiT study group. Re-analysis of histology in testicular cancer

Residual retroperitoneal masses may remain after chemotherapy for metastatic non-seminomatous testicular cancer, which harbour residual tumour or totally benign tissue (necrosis/fibrosis). These residual masses may be effectively removed by a surgical resection. We evaluated current selection criteria and tried to develop alternative criteria in a data set of 544 patients, who had retroperitoneal lymph node dissection of residual masses. Six resection policies were identified from the literature. Two alternative policies were developed with logistic regression analysis. Evaluation of the policies focused on the true-positive rate (resection in case of tumour), and the false-positive rate (resection in case of necrosis). It appeared that most current policies use the size of the residual mass (> or = 10 mm or > or = 20 mm) as the predominant selection criterion. This resulted in high true-positive rates (most > 90%), but false-positive rates between 37% and 87%. The alternative policies included five well-known predictors of necrosis in addition to residual mass size (primary tumour histology, prechemotherapy levels of the three tumour markers alphafetoprotein (AFP), human chorionic gonadotropin (HCG) and lactate dehydrogenase (LDH) and mass shrinkage during chemotherapy). This strategy resulted in improved true- and false-positive rates, even when categories of the predictors were simplified for practical application. We conclude that a simple statistical model, based on a limited number of patient characteristics, provides better guidelines for patient selection than those currently used in clinical practice.     

Tyrosine kinase activity modulates catalysis and translocation of cellular 5-lipoxygenase

Tyrosine kinase activity, a determinant of Src homology domain interactions, has a prominent effect on cellular localization and catalysis by 5-lipoxygenase. Six separate inhibitors of tyrosine kinase each inhibited 5(S)-hydroxyeicosatetraenoic acid formation by HL-60 cells stimulated with calcium ionophore, in the presence or absence of exogenous arachidonic acid substrate, indicating that they modulated cellular 5-lipoxygenase activity. The tyrosine kinase inhibitors also blocked the translocation of 5-lipoxygenase from cytosol to membranes during cellular activation, consistent with their effects on its catalytic activity. These results fit a model which postulates that Src homology domain interactions are a molecular determinant of the processes which coordinate the subcellular localization and functions of 5-lipoxygenase. In addition, we demonstrate that activated leukocytes contain two molecularly distinct forms of 5-lipoxygenase: a phosphorylated form and a nonphosphorylated form. In activated HL-60 cells the pool of phosphorylated 5-lipoxygenase accumulates in the nuclear fraction, not with the membrane or cytosolic fractions. The amount of phosphorylated 5-lipoxygenase is a small fraction of the total. Overall, equilibrium reactions involving the nuclear localizing sequence, the proline-rich SH3 binding motif, and the phosphorylation state of 5-lipoxygenase may each influence its partnership with other cellular proteins and any novel functions derived from such partnerships.     

Near-infrared spectroscopy: theory and applications

In conclusion, NIRS appears to offer both a new monitoring modality and new information about cerebral oxygenation. Technical problems in the application of this technology persist, most notably determination of pathlength and the volume of tissue interrogated. Those familiar with the history of pulse oximetry will recall that although Millikan developed an ear oximeter in 1947, it was not until Aoyagi combined recognition of the pulse signal with spectroscopy in the 1970s that oximetry was transformed into a clinically applicable monitor. In much the same way, NIRS may find the same tremendous usefulness as a noninvasive monitor of cerebral oxygen utilization, pending resolution of the remaining technical problems.     

In vitro-in vivo relationships for oral extended-release drug products

It is of interest to predict the in vivo behavior of an oral extended-release drug product based on its in vitro dissolution profile. In some cases a suitable convolution-based prediction model can be found. We present a methodology for developing statistical models of in vitro-in vivo relationships under the framework of the mixed-effects nonlinear model and discuss methods for assessing the validity and strength of the relationship. These methods are illustrated and contrasted with a level A in vitro-in vivo correlation using data from a study involving four different formulations of an oral extended-release drug product.     

Regulation of expression of a cDNA from barley roots encoding a high affinity sulphate transporter

A cDNA encoding a high-affinity sulphate transporter has been isolated from barley by complementation of a yeast mutant. The cDNA, designated HVST1, encodes a polypeptide of 660 amino acids (M(r) = 72,550), which is predicted to have 12 membrane-spanning domains and has extensive sequence homology with other identified eukaryotic sulphate transporters. The K(m) for sulphate was 6.9 microM when the HVST1 cDNA was expressed in a yeast mutant deficient in the gene encoding for the yeast SUL1 sulphate transporter. The strong pH-dependency of sulphate uptake when HVST1 was expressed heterologously in yeast suggests that the HVST1 polypeptide is a proton/sulphate co-transporter. The gene encoding HVST1 is expressed specifically in root tissues and the abundance of the mRNA is strongly influenced by sulphur nutrition. During sulphur-starvation of barley, the abundance of mRNA corresponding to HVST1, and the capacity of the roots to take up sulphate, both increase. Upon re-supply of sulphate, the abundance of the mRNA corresponding to HVST1, and the capacity of the roots to take up sulphate, decrease rapidly, concomitant with rises in tissue sulphate, cysteine and glutathione contents. Addition of the cysteine precursor, O-acetylserine, to plants grown with adequate sulphur supply, leads to increases in sulphate transporter mRNA, sulphate uptake rates and tissue contents of glutathione and cysteine. It is suggested, that whilst sulphate, cysteine and glutathione may be candidates for negative metabolic regulators of sulphate transporter gene expression, this regulation may be overridden by O-acetylserine acting as a positive regulator.     

Cell density downregulates DNA synthesis and proliferation during osteogenesis in vitro

The classical models of in vitro cell culture comprise fibroblasts and epithelial cells. Osteogenic cells represent another interesting cell model; however, it is not known whether during osteogenesis cell density regulates cell growth as seen in cultures of fibroblasts and epithelial cells. We selected MC3T3-E1 cells for study because they are an osteogenic cell line that, when subcultured, grow to confluence and form multilayers of cells in conventional cultures by continued proliferation, as do fibroblasts. Once maximum cell density is obtained, proliferation is down regulated resulting in a mixed population of quiescent and dividing cells. We used this model to determine whether downregulation of proliferation as expressed by cell number and DNA synthesis is cell density-dependent. MC3T3-E1 cells were cultured over a period of 34 days to determine their kinetics, viability, ability to synthesize DNA, distribution within phases of the cell cycle and cell number-response relationships. Our results show that (1) viability ranged between 92% and 96% and the cell number 2.5 x 10(5) per cm2 once cultures reached steady state, (2) most cells entered the G0/G1 phase of the cell cycle on day 7, (3) there was no correlation between the proportion of cells in S phase and downregulation of DNA synthesis, (4) a direct relationship exists between cell density and downregulation of DNA synthesis on day 8, (5) the minimum time for cells to be cultured before downregulation of DNA synthesis begins is independent of cell number, and (6) downregulation of DNA synthesis is reversible. These results suggest that density-dependent downregulation of DNA synthesis may be a mechanism of growth control for osteogenic cells in vitro that operates more like density-dependent growth control in cultures of fibroblasts rather than epithelial cells.