Severe respiratory distress syndrome unresponsive to intensive care treatment--diagnostic and therapeutic considerations.

Respiratory Distress Syndrome (RDS) is a common complication in preterm neonates. If RDS is not responding to conventional treatment modalities (surfactant therapy, ventilatory support, etc.), an underlying pathology (pulmonary lymphangiectasia, capillary alveolar dysplasia, alpha-1 antitrypsin deficiency, etc.) other then prematurity should be taken into consideration.Here, we report on a preterm neonate with the unusual simultaneous occurrence of pulmonary and systemic lymphangiectasia and homozygous alpha-1 antitrypsin deficiency who developed severe RDS that was refractory to conventional treatment. The diagnostic and therapeutic approach in this patient is presented.

Congenital disorders of glycosylation type Ia as a cause of mirror syndrome.

Mirror syndrome (that is fetal hydrops with subsequent edema in the pregnant woman) is a rare condition. Early diagnosis is warranted, as maternal and fetal morbidity and mortality is increased if not diagnosed and treated properly. In most cases, the underlying cause remains unclear. We report a woman who has had two pregnancies complicated by mirror syndrome. Congenital disorder of glycosylation type Ia (CDG-Ia) was identified as the underlying fetal disease in both cases.

Calculation of the dielectric properties of a protein and its solvent: theory and a case study.

This paper presents a rigorous derivation of a theory for the calculation of the frequency-dependent dielectric properties of each component of the system protein/water/ions with the aim of enabling comparison to experimentally determined dielectric properties. We apply this theory to a very long (13.1 ns) molecular dynamics simulation of an HIV1 zinc finger peptide, its co-ordinated zinc ion, and two chloride ions in a box of SPC/E water molecules. We find the dielectric relaxation of the water molecules restricted compared to pure water, giving rise to a static dielectric constant for the water-component of only 47. The peptide is found to have a complicated dielectric relaxation behaviour, with a static dielectric constant of 15. We also calculate the frequency-dependent conductivity of the ions in this system. We analyze all contributions to the calculation of these dielectric properties and find that the coupling between the dielectric relaxation of the peptide and that of the water-component is particularly important for correctly describing the dielectric constant of the peptide.

The role of PDGF-dependent suppression of apoptosis in differentiating 3T3-L1 preadipocytes.

In a chemically defined serum-free culture system, platelet-derived growth factor (PDGF) as the only externally applied growth factor, in concert with corticosterone, 3-isobutyl-1-methylxanthine (IBMX) and low insulin (1nM), stimulates adipose conversion of 3T3-L1 preadipocytes. Omission of PDGF during the induction period results in loss of differentiation competence and apoptotic cell death. Induction of apoptosis is shown to be clearly mediated by PDGF withdrawal, since neither corticosterone nor IBMX affect the apoptotic behaviour of 3T3-L1 cells. Cell viability in the absence of the survival factor PDGF could be achieved by application of high insulin (1 microM) or ectopical expression of the anti-apoptotic proto-oncogene Bcl-2. However, PDGF-independent suppression of cell death does not trigger adipose conversion in the presence of corticosterone and IBMX. Therefore, we conclude that suppression of apoptosis per se is not permissive for differentiation of 3T3-L1 preadipocytes and PDGF might exert some additional differentiation-promoting effect(s).

The human breast cancer cell line MDA-MB231 produces an aromatase stimulating activity.

Extraovarian estrogen production is localized mainly in stromal vascular cells from adipose tissue, which contain the aromatase activity necessary for the conversion of androgens to estrogens. Induction of aromatase activity in these cells by glucocorticoids occurs only in the presence of a serum factor, the properties and origin of which are unknown (serum-derived aromatase stimulating activity, serum-ASA). Cells of the breast cancer line MDA-MB231 produce a factor resembling serum-ASA, as it is able to completely replace serum during the induction of aromatase by glucocorticoids. MDA-MB231-derived ASA is destroyed by proteolytic digestion and is purified about 100-fold by ultrafiltration of MDA-MB231 conditioned media and anion exchange chromatography.

Influence of growth factors on growth and differentiation of 3T3-L1 preadipocytes in serum-free conditions.

The role of platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) in the adipose differentiation of 3T3-L1 preadipocytes was investigated in a chemically defined culture system. To eliminate the influence of unidentified adipogenic compounds present in serum or serum-derived medium additives, cells from a stock culture were grown to confluence under serum-free conditions in the presence of recombinant PDGF and insulin. To trigger differentiation of these cells, the usual stimuli for adipogenesis such as corticosterone and insulin at supraphysiological concentrations together with 3-isobutyl-1-methylxanthine were required but not sufficient for maximal stimulation. Either PDGF or EGF had to be added with insulin at a supraphysiological concentration or insulin-like growth factor-1 for four days in order to obtain complete differentiation. These results indicate that differentiation of 3T3-L1 preadipocytes is possible by replacing unknown serum factors by a combination of defined growth factors.

Glucocorticoid hormones contribute to the adipogenic activity of human serum.

The adipose conversion of 3T3-L1 fibroblasts depends on serum factors, one of which has been identified as GH. Human serum extracts obtained by heat treatment do not contain intact GH, as shown by RIA, but still support adipose conversion. After organic solvent extraction followed by reversed phase HPLC, two adipogenic fractions can be purified. Their identification as cortisol and cortisone follows from the observations that both glucocorticoid hormones are strongly adipogenic in physiological concentrations and elute upon reversed phase HPLC with retention times identical to those of the adipogenic fractions. After derivatization by acetylation, the adipogenic fractions purified from human serum again do not differ from C-21 monoacetyl cortisol and -cortisone with regard to adipogenic activity and behavior on reversed phase HPLC and TLC. Treatment of heat extracts from human serum with cortisol antibodies strongly reduced their adipogenic activity which could be restored only after addition of cortisol to the original concentration. We conclude from these results, that the adipogenic activity of human serum depends mainly on its glucocorticoid (as well as GH) concentration.

Induction of aromatase in stromal vascular cells from human breast adipose tissue depends on cortisol and growth factors.

The regulation of aromatase (estrogen synthase) activity of cultured stromal vascular cells from human breast adipose tissue by cortisol, db-cAMP and growth factors was studied in a serum-free culture system. While PDGF-BB alone inhibited the effect of db-cAMP on aromatase induction, it stimulated aromatase activity in the presence of cortisol with or without db-cAMP. In the presence of 1 microM insulin consistently higher aromatase activities were found as compared to 1 nM insulin. In contrast to PDGF-BB, bFGF led to an increase of aromatase activity only in the presence of both cortisol and db-cAMP.

An adipogenic serum factor in genetically obese rodents.

The adipose conversion of 3T3-Li cells depends on a serum factor present in high amounts in fetal calf serum, which is heat stable and can be extracted from serum by ethanol precipitation. Sera of two genetically obese rodent species, fa/fa Zucker rats and C57Bl/KsJ-db/db mice, contain a high adipogenic activity which is very similar to that found in fetal calf serum. In contrast, sera of their lean siblings (Fa/Fa-Zucker rats and C57Bl/KsJ-+/+ mice) are devoid of adipogenic activity.

A cytotoxic monoclonal antibody specific for the private alloantigenic determinant of the HLA-B 13 molecule.

A murine monoclonal antibody (TU 110) prepared against blast cells of a patient with acute "undifferentiated" leukemia was tested in the microcytotoxicity assay on peripheral blood lymphocytes of 122 normal Caucasian donors. The TU 110 reactivity was found to show a correlation coefficient of 1.0 in population analysis for the presence of the HLA-B locus specificity B 13 as defined by alloantisera. Family segregation studies confirmed MHC linked inheritance of the TU 110 antigenic determinant strictly on HLA-B 13 positive haplotypes. As the first monoclonal reagent against the private specificity of this HLA-B locus antigen, TU 110 provides the possibility to study the structural relationships of sub- and supertypic determinants on this allotype and may help to correlate antigenic domains of HLA-B 13 with definable functional properties.

Progesterone inhibits glucocorticoid-dependent aromatase induction in human adipose fibroblasts.

In fibroblasts derived from human adipose tissue, aromatase induction is observed after exposure to 1 microM cortisol in the presence of serum or platelet-derived growth factor (PDGF). Progesterone suppresses this induction in a dose-dependent manner, 10 microM resulting in complete inhibition. A reduced cortisol concentration (0.1 microM) concomitantly reduces the progesterone concentration required for effective inhibition (10-100 nM). This effect of progesterone is specific, as neither the release of cellular enzymes nor aromatase induction by dibutyryl-cAMP, which acts independently from cortisol, are affected. However, the inhibitory effect of progesterone requires its presence throughout the induction period. Kinetic studies in intact cells reveal a reduced number of aromatase active sites upon progesterone treatment, whereas progesterone at near-physiological concentration (100 nM) does not inhibit aromatase activity in isolated microsomes. Semi-quantitative reverse transcriptase PCR analysis shows reduced amounts of aromatase mRNA in progesterone-treated cells, indicating specific inhibition of the glucocorticoid-dependent pathway of aromatase induction. The inhibitory effect of progesterone is not blocked by the anti-progestin ZK114043, excluding action via progesterone receptors and indicating competition for the glucocorticoid receptor. Progesterone must be considered a potential physiological inhibitor of glucocorticoid-dependent aromatase induction in adipose tissue. It is proposed that it is a suppressor of aromatase induction in adipose tissue in premenopausal women.

Conversion of dehydroepiandrosterone to downstream steroid hormones in macrophages.

Dehydroepiandrosterone (DHEA) is a ubiquitous adrenal hormone with immunomodulatory effects such as inhibition of the production of monokines. Whether DHEA itself or the downstream steroids are the immunomodulatory effector hormones in target cells is not known. In this study, we investigated the conversion of DHEA to downstream steroid hormones in target macrophages. Within 1 day of culture with radiolabeled DHEA, monocyte-derived macrophages converted DHEA to significant amounts of Delta5-derivatives such as 16OH-DHEA, 3beta, 17beta-androstenediol (A'diol), and 3beta,16alpha, 17beta-androstenetriol (A'triol). However, the production of Delta4-steroids (androstenedione (A'dione), testosterone (T), and 16OH-T) and estrogens (estrone, estradiol, and estriol) was relatively low. Further cultivation of macrophages for 5 days with radiolabeled DHEA resulted in a significant (P<0.05) increase of the molar amounts of A'triol (P=0.012), 16OH-T (P=0.008), and estriol (P=0.003). In contrast to monocyte-derived macrophages, monocytes did not express aromatase mRNA, which was demonstrated by RT-PCR (P<0.01). Furthermore, DHEA in macrophages significantly inhibited one of the downstream converting enzymes, the aromatase, which was not demonstrated in the presence of the typical macrophage activator, lipopolysaccharide (LPS) (P<0.01). In conclusion, conversion of DHEA to physiologically relevant amounts of Delta5- and Delta4-steroids and estrogens was demonstrated in monocyte-derived macrophages. The conversion depends on maturation of monocytes and local factors such as the presence of LPS. The conversion of DHEA leads to an increase of downstream effector hormones in target macrophages which may be an important factor for local immunomodulation.

RU486 is a potent inhibitor of aromatase induction in human breast adipose tissue stromal cells.

Aromatization of circulating androgens in adipose tissue is a major source of estrogens in postmenopausal women. As part of our efforts to elucidate the mechanism of aromatase induction in human breast adipose tissue, we tested the effects of the antiglucocorticoid and antiprogestin, RU486, on aromatase induction in primary cultures of adipose tissue stromal cells in a serum-free system devoid of phenol-red. Under these conditions 1 microM cortisol alone induces low levels of aromatase activity within one day, whereas platelet-derived growth factor BB (PDGF) potentiates this effect two- to three-fold. The well-known strong inductive effect of dibutyryl-cAMP (db-cAMP) is also augmented by cortisol, but is inhibited by PDGF in the absence of cortisol. RU486 completely prevented aromatase induction by cortisol and PDGF. Induction by db-cAMP in the presence and absence of cortisol was significantly inhibited by RU486. Even lower activities were measured when RU486 was added to cells stimulated with PDGF and db-cAMP in the absence or presence of cortisol. Similar results were obtained after prolonged incubation. The inhibitory effects of RU486 are dose dependent, less than 1 microM completely blocking the effects of cortisol, whereas 10 microM are needed to block db-cAMP induction. RU486 does not affect cell number, cellular protein, viability or house-keeping enzymes such as lactate dehydrogenase (LDH), and therefore seems to act specifically. The time course of RU486 action on the db-cAMP induction of aromatase indicates that it acts via a newly synthetized mediator or target in stromal cells. These results suggest that all known inducers of aromatase in adipose tissue depend upon the action of signalling molecules (probably members of the nuclear receptor superfamily) which can be blocked by RU486. The inhibitory action of PDGF seems to be independent of steroid hormone action, as seems some basal activity induced by db-cAMP. In conclusion, this in vitro study suggests that RU486 might be a useful tool for the therapy of estrogen-dependent tumours through its inhibition of aromatase induction.

Fluorescent microsphere method is suitable for chronic bone blood flow measurement: a long-term study after meniscectomy in rabbits.

The fluorescent microsphere (FM) method is considered a reliable technique to determine regional bone blood flow (RBBF) in acute experiments. In this study, we verified the accuracy and validity of this technique for measurement of RBBF in a long-term experiment and examined RBBF after meniscectomy. Twenty-four anesthetized female New Zealand white rabbits (3 groups, each n = 8) received consecutive left ventricular injections of FM in defined time intervals after meniscectomy: group 1 from preoperation to 3 wk postoperation; group 2 from 3 to 7 wk postoperation; and group 3 from 7 to 11 wk postoperation. To test the precision of the FM method, two FM species were injected simultaneously at the first and last measurement. After the experiment, humeri, femora, tibiae, and reference organs (kidney, lung, brain) were removed and dissected according to standardized protocols. Fluorescence was determined in each reference blood and tissue sample, and blood flow values were calculated. Blood flow in kidney, lung, and brain revealed no significant difference between right and left side and remained unchanged during the observation period, thus excluding errors due to shunting and dislodging of spheres in our experiments. Comparison of relative bone blood flow values obtained by simultaneously injected FM showed an excellent correlation at the first and last injection, indicating valid RBBF measurements in long-term experiments. We found a significant increase in RBBF 3 wk after meniscectomy in the right tibial condyles compared with the nonoperated left side. Similar changes were found in the femoral condyles. RBBF in other regions of tibia, femur, and humerus revealed no significant differences between right- and left-sided bone samples of the same region. Our results demonstrate that the FM method is valid for measuring RBBF in long-term experiments. In addition, we were able to demonstrate that meniscectomy leads to an increase in RBBF in the tibial condyles at a very early stage. This increase might be caused by stress-induced alterations of the subchondral bone.

Computing feature motion without feature detectors: a model for terminator motion without end-stopped cells.

Pointlike object features such as line-endings, have a privileged position in the computation of the veridical direction of object motion. Experiments confirm that the human visual system relies heavily on such features if they are present. It has been proposed that units such as end-stopped cells might be necessary for the computation of feature motion instead of the simple cells used in plaid motion models. Conventional plaid motion models have not been applied to feature motion. We present here a model, based on ordinary simple cells, using two parallel pathways (Fourier and non-Fourier) for the computation of the direction of two dimensional motion. Although similar in structure to popular models of plaid motion, our model includes a novel scheme for contrast normalisation and incorporates spatial pooling at the level of MT cells. The model predictions are consistent with psychophysical results for plaids. Furthermore, it computes directions within 5 degrees of the physical motion of line-endings. It is shown that the non-Fourier signal is necessary for the computation of veridical motion.

Detecting shape deformation of moving patterns.

This study measured thresholds for the discrimination of rigidly and nonridgidly rotating patterns in two dimensions. The stimuli employed were closed contours created by the sum of two 'radial frequency' components and sensitivity to their deformation was measured as a function of the difference in the angular velocities of the components. Results show that thresholds do not depend on the specific shape of the pattern. To quantify the influence of local computations versus global pooling, thresholds were measured with parts of the pattern covered by (invisible) pie-shaped apertures. One finds thresholds are not simply a function of the total amount of pattern visible but exhibit a dependence on the number of apertures. Moreover, sensitivity to deformation could neither be fully explained on the basis of local computations nor by linear global summation. A simultaneous masking paradigm was employed to elucidate potential mechanisms involved in the computation of deformation. While 1D masks (horizontal gratings and translating random dots) only marginally elevate thresholds, rotating and expanding motion significantly impairs sensitivity. This indicates that detectors tuned to radial and circular motion are involved in the computation of shape deformation.

Anisotropy in judging the absolute direction of motion.

The angular dependence of precision measurements is well established as the oblique effect in motion perception. Recently, it has been shown that the visual system also exhibits anisotropic behaviour with respect to accuracy of the absolute direction of motion of random dot fields. This study aimed to investigate whether this angular dependent, directional bias is a general phenomenon of motion perception. Our results demonstrate, for single translating tilted lines viewed foveally, an extraordinary illusion with perceptual deviations of up to 35 degrees from veridical. Not only is the magnitude of these deviations substantially larger than that for random dots, but the general pattern of the illusion is also different from that found for dot fields. Significant differences in the bias, as a function of line tilt and line length, suggest that the illusion does not result from fixed inaccuracies of the visual system in the computation of direction of motion. Potential sources for these large biases are motion integration mechanisms. These were also found to be anisotropic. The anisotropic nature and the surprisingly large magnitude of the effect make it a necessary consideration in analyses of motion experiments and in modelling studies.

An inverse oblique effect in human vision.

In the classic oblique effect contrast detection thresholds, orientation discrimination thresholds, and other psychophysical measures are found to be smallest for vertical or horizontal stimuli and significantly higher for stimuli near the +/-45 degrees obliques. Here we report a novel inverse oblique effect in which thresholds for detecting translational structure in random dot patterns [Glass, L. (1969). Moiré effect from random dots. Nature, 223, 578-580] are lowest for obliquely oriented structure and higher for either horizontal or vertical structure. Area summation experiments provide evidence that this results from larger pooling areas for oblique orientations in these patterns. The results can be explained quantitatively by a model for complex cells in which the final filtering stage in a filter-rectify-filter sequence is of significantly larger area for oblique orientations.

Biomass steam gasification--an extensive parametric modeling study.

A model for steam gasification of biomass was developed by applying thermodynamic equilibrium calculations. With this model, the simulation of a decentralized combined heat and power station based on a dual fluidized-bed steam gasifier was carried out. Fuel composition (ultimate analysis and moisture content) and the operating parameters, temperature and amount of gasification agent, were varied over a wide range. Their influences on amount, composition, and heating value of product gas and process efficiencies were evaluated. It was shown that the accuracy of an equilibrium model for the gas composition is sufficient for thermodynamic considerations. Net electric efficiency of about 20% can be expected with a rather simple process. Sensitivity analysis showed that gasification temperature and fuel oxygen content were the most significant parameters determining the chemical efficiency of the gasification.