Arachidonic acid uptake by human platelets is mediated by CD36

The involvement of glycoprotein (GP) IV (CD36) in arachidonic acid uptake by human platelets was investigated using an anti-CD36 monoclonal antibody (MAB). The binding of [(14)C]arachidonic acid to MAB-treated platelets was significantly reduced compared with untreated platelets. The MAB also inhibited arachidonic acid-induced platelet aggregation and thromboxane A(2) synthesis in a dose-dependent manner. Pre-incubation of gel-filtered platelets with the MAB (10mg/I) inhibited arachidonic acid-induced platelet aggregation by 50% and collagen-induced platelet aggregation by 7-8% and the lag time was increased by 200%. Although the mechanism of platelet aggregation is not fully understood yet, the inhibition of arachidonic acid-induced platelet aggregation by the MAB could be the result of a reduced uptake of exogeneously added arachidonic acid by the MAB-treated platelets. Our data clearly indicate that arachidonic acid uptake by platelets is mediated, at least in part, by CD36.

Reflection-mode, confocal, tip-enhanced Raman spectroscopy system for scanning chemical microscopy of surfaces

A reflection-mode, confocal, tip-enhanced Raman spectroscopy system for nanoscale chemical imaging of surfaces is presented. The instrument is based on a beam-bounce atomic force microscope with a side-on Raman microscope with true confocal light illumination and collection. Localized vibrational (Raman) spectroscopy is demonstrated at length scales down to 20 nm on opaque samples. The design and validation of the instrument are discussed with quantitative emphasis on confocal microscope operation, plasmonic properties of the tip, point spectroscopy, and Raman imaging of SiGe nanowires.

Inhibitory effect of Ginkgo biloba extract on human platelet aggregation

The effect of pure flavonoids and Gingko biloba extract (GBE) on human platelet aggregation was investigated. Most of the flavonoids and vitamin E did not affect platelet aggregation in platelet-rich plasma (PRP); however some of these flavonoids inhibited platelet aggregation in gel-filtered platelets (GFP). GBE inhibited both ADP- and collagen-induced platelet aggregation in PRP, GFP and in whole blood in a dose-dependent manner. GBE at very low concentrations inhibited whole blood aggregation induced by ADP compared with those used for PRP or GFP. Flavonoids and GBE decreased the production of TxA(2) induced by collagen and ADP in PRP. However, no correlation was observed between the inhibition of platelet aggregation and the decrease of TxA(2) synthesis. GBE and flavonoids did not affect platelet membrane fluidity. However, the incubation of PRP with GBE increased cAMP levels in platelets, which is known to inhibit platelet activation by lowering intracellular Ca2+ levels. GBE is a mixture of many compounds, including flavonoids and gingkoglides, which affect metabolism of cAMP, TxA(2) and Ca2+ in platelets. It is effective in the inhibition of platelet aggregation, both in PRP and whole blood, and thus may be potentially used as an effective oral anti-platelet therapeutic agent.

Fermi surface of CeIn3 above the Néel critical field

We report measurements of the de Haas-van Alphen effect in CeIn(3) in magnetic fields extending to approximately 90 T, well above the Néel critical field of mu(0)H(c) approximately 61 T. The unreconstructed Fermi surface a sheet is observed in the high magnetic field polarized paramagnetic limit, but with its effective mass and Fermi surface volume strongly reduced in size compared to that observed in the low magnetic field paramagnetic regime under pressure. The spheroidal topology of this sheet provides an ideal realization of the transformation from a "large Fermi surface" accommodating f electrons to a "small Fermi surface" when the f-electron moments become polarized.

Evidence of simultaneous double-electron promotion in F+ collisions with surfaces

A high-flux beam of mass-filtered F+ at low energy (100-1300 eV) was scattered off Al and Si surfaces to study core-level excitations of F0 and F+. Elastic scattering behavior for F+ was observed at energies <300 (500) eV off Al (Si) for a 90 degrees lab angle. However, above this energy threshold, orbital mixing in the hard collision step results in electronic excitation of F via molecular orbital promotion along the 4f sigma (F-2p), significantly reducing the observed ion exit energy. In addition, despite the electronegativity of F, scattering at energies >450 (700) eV off Al (Si) produces F2+-behavior which is remarkably similar to Ne+ off the same surfaces. Inelasticities measured for single collision events agree well with the energy deficits required to form (doubly excited) F** and F+** states from F0 and F+, respectively; these excited species most likely decay to inelastic F+ and F2+ via autoionization.

Effects of tomato extract on human platelet aggregation in vitro

Among all fruits tested in vitro for their anti-platelet property, tomato had the highest activity followed by grapefruit, melon, and strawberry, whereas pear and apple had little or no activity. Tomato extract (20-50 microl of 100% juice) inhibited both ADP- and collagen-induced aggregation by up to 70% but could not inhibit arachidonic acid-induced platelet aggregation and concomitant thromboxane synthesis under similar experimental conditions. The anti-platelet components (MW <1000 Da) in tomatoes are water soluble, heat stable and are concentrated in the yellow fluid around the seeds. The active fractions were separated using gel filtration and HPLC. The aqueous fraction (110 000 xg supernatant) of tomatoes containing anti-platelet activity was subjected to gel filtration column chromatography (Biogel P2 column). The activity was fractionated into two peaks, peak-3 and peak-4 (major peak). Subsequently, peak-4 was further purified by HPLC using a reversed-phase column. NMR and mass spectroscopy studies indicated that peak F2 (obtained from peak 4) contained adenosine and cytidine. Deamination of peak F2 with adenosine deaminase almost completely abolished its anti-platelet activity, confirming the presence of adenosine in this fraction. In comparison, deamination of peak-4 resulted in only partial loss of inhibitory activity while the activity of peak-3 remained unaffected. These results indicate that tomatoes contain anti-platelet compounds in addition to adenosine. Unlike aspirin, the tomato-derived compounds inhibit thrombin-induced platelet aggregation. All these data indicate that tomato contains very potent anti-platelet components, and consuming tomatoes might be beneficial both as a preventive and therapeutic regime for cardiovascular disease.

Clinical outcomes in reduction mammaplasty: a systematic review and meta-analysis of published studies

This systematic review and meta-analysis were undertaken to determine whether reduction mammaplasty improves measurable outcomes in women with breast hypertrophy. A systematic review of the literature in 5 languages from 1985 until March 1999 was performed, and data were compared for meta-analysis. Eligible studies were both experimental and observational and involved women with preoperative physical and/or psychosocial signs and symptoms who underwent reduction mammaplasty for breast hypertrophy. Outcomes assessed were postoperative physical signs and symptoms such as shoulder pain, shoulder (bra strap) grooving, and quality-of-life domains, such as physical and psychological functioning, and were expressed primarily as risk differences (RDs). Twenty-nine studies of 4173 patients met all eligibility criteria. Reduction mammaplasty was associated with a statistically significant improvement in physical signs and symptoms involving shoulder pain (RD, 0.71 [95% confidence interval (CI), 0.62-0.80]); shoulder grooving (RD, 0.69 [95% CI, 0.60-0.78]); upper/lower back pain (RD, 0.59 [95% CI, 0.48-0.70]); neck pain (RD, 0.50 [95% CI, 0.37-0.64]); intertrigo (RD, 0.44 [95% CI, 0.34-0.54]); breast pain (RD, 0.36 [95% CI, 0.17-0.55]); headache (RD, 0.28 [95% CI, 0.11-0.46]); and pain/numbness in the hands (RD, 0.11 [95% CI, 0.04-0.18]). The quality-of-life parameter of physical functioning was also statistically significant (RD, 0.58 [95% CI, 0.44-0.71]), while psychological functioning was not significant (RD, 0.46 [95% CI, 0.00-1.00]). The evidence suggests that women undergoing reduction mammaplasty for breast hypertrophy have significant postoperative improvement in preoperative signs and symptoms, quality of life, or both.

Preferential distribution of long chain polyunsaturated fatty acids in phospatidyl ethanolamine fraction of guinea pig alveolar apical membranes

We investigated the fatty acid distribution in guinea pig alveolar apical membranes at different developmental stages. Fatty acid composition of the purified membranes isolated from guinea pig fetuses (at 65 day, term=68 day), neonates (day 1) and adult males was determined. The levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in the adult guinea pig alveolar apical membrane phosphatidylethanolamine (PE) fraction (9. 3+/-2.2 and 2.9+/-1.0%, respectively) while in other phospholipids (PL) fractions their levels were low or absent (P<0.01). Furthermore, levels of AA and DHA in the PE fraction of apical membrane increased significantly from fetal (6.6+/-3.0 and 0.8+/-0.4%, respectively) to neonatal life (10.3+/-1.5 and 3.0+/-0.8%, respectively). Increase in the level of DHA (almost four-fold) was much more pronounced than that of AA (P<0.05). As for guinea pig alveolar membranes, EPA and AA were mostly present in the PE fraction in pulmonary adenocarcinoma derived cells (A549 cells), a parallel model of type II pneumocytes, with the levels of AA around three-fold greater than that of EPA, Binding of radiolabelled fatty acids to A549 cells showed no significant differences between the maximum uptake achieved for different fatty acids (AA, 1.7+/-0.2, EPA, 2.3+/-0.3, LA, 1.7+/-0.2, OA, 2.0+/-0.2nmol/mg protein, P>0.5). Once the fatty acids were taken up by these cells AA was mostly identifiable in the monoacylglycerol (MAG) fraction, whereas EPA was equally distributed between the MAG and PL fractions. Oleic acid was mainly present in the triglyceride (TAG) fraction whereas LA was evenly distributed between the TAG, MAG, and PL fractions. Our data demonstrate a preferential distribution of AA and DHA in PE fractions of alveolar apical membranes during development.

Adverse drug reactions in hospitalized patients: A critique of a meta-analysis

OBJECTIVE

To replicate and to critique a recently published meta-analysis[1] of the incidence of nonpreventable serious and fatal adverse drug reactions (ADRs) in hospitalized patients, to better understand its results and conclusions.

METHODS

The published methods described in the meta-analysis of Lazarou and colleagues were followed.[1] This meta-analysis reviewed 30 original publications describing 39 prospective studies. In each study, the numbers of patients with nonpreventable ADRs, probably or definitely related to drugs, were sought to allow calculation of the incidence of "all-severities," serious and fatal, ADRs. In the original meta-analysis, these ADR incidences were then pooled to provide estimates of the incidence in all hospitalized patients. In our analysis, the original studies were examined by 2 investigators for consistency with the study search and inclusion criteria of the meta-analysis by Lazarou and colleagues, as well as accuracy and appropriateness of data extraction, meta-analysis, and conclusions.

RESULTS

Multiple sources of heterogeneity among studies and data were found and include important differences in populations and hospital wards monitored, surveillance techniques, ADR definitions, determination of preventability of ADRs, distinguishing relationship to drugs, and in formats of reporting ADRs (by numbers of events or by patients). Imputations of event numerators made by the authors of the original meta-analysis were questionable and may overestimate the results of any individual study. With regard to fatal ADRs, the problem of small numbers of events is likely to introduce large errors in incidence estimates. Simple pooling of fatal event frequencies from only those studies specifically reporting the number of fatal ADRs, as was done in the meta-analysis of Lazarou and colleagues, is likely to dramatically overestimate the death rate.

CONCLUSION

Meta-analysis was invalid because of heterogeneity of the studies. Most of these studies did not report the data needed for incidence calculations. The methodology used was seriously flawed, and no conclusions regarding ADR incidence rates in the hospitalized population in the United States should be made on the basis of the original meta-analysis.

Measurement of Gd-DTPA diffusion through PVA hydrogel using a novel magnetic resonance imaging method

Polyvinyl alcohol-cryogel (PVA-C) is a hydrogel that is an excellent tissue mimic. In order to characterize mass transfer in this material, as well as to demonstrate in principle the ability to noninvasively measure solute diffusion in tissue, we measured the diffusion coefficient of the magnetic resonance (MR) contrast agent gadolinium diethylene triaminopentaacetic acid (Gd-DTPA) through PVA-C using a clinical MR imager. The method involved filling thick-walled rectangular PVA-C "cups" with known concentrations of Gd-DTPA solutions. Then by using a fast inversion recovery spin echo MR imaging protocol, a signal "null" contour was created in the MR image that corresponded to a second, known concentration of Gd-DTPA. By collecting a series of MR images through the PVA-C wall as a function of time, the displacement of this second known isoconcentration contour could be tracked. Application of Fick's second law of diffusion yielded the diffusion coefficient. Seven separate experiments were performed using various combinations of initial concentrations of Gd-DTPA within the PVA-C cups (3.2, 25.6, or 125 mM) and tracked isoconcentrations contours (0.096, 0.182, or 0.435 mM Gd-DTPA). The experimental results and the predictions of Fick's law were in excellent agreement. The diffusivity of Gd-DTPA through 10% PVA hydrogel was found to be (2.6 +/- 0.04) x 10(-10) m(2)/s (mean +/- s.e.m.). Separate permeability studies showed that the diffusion coefficient of Gd-DTPA through this hydrogel did not change with an applied pressure of up to 7.1 kPa. Accurate measurements could be made within 30 min if suitable Gd-DTPA concentrations were selected. Due to the excellent repeatability and fast data acquisition time, this technique is very promising for future in vivo studies of species transport in tissue.

Restoring hand function in patients with severe polyneuropathy: the role of electromyography before tendon transfer surgery

Electromyography (EMG) was evaluated as a supplement to clinical examination and biomechanical considerations to optimize forearm donor muscle selection before tendon transfers to 4 functionless hands in 3 patients with slowly progressive polyneuropathies. Two patients had unusually severe Charcot-Marie-Tooth disease; the third patient had idiopathic mononeuropathy multiplex. Standard EMG parameters were used to devise an intuitive muscle grading system, including most importantly interference patterns and motor control, plus motor unit morphology and stability. Given our objective of restoring survivable function despite ongoing polyneuropathy, we found that EMG reveals prognostically important differences among partially denervated candidate muscles that cannot be detected by experienced clinical examiners. Opposition transfer was performed on one hand of each patient. After 39-, 39-, and 51-month follow-up durations, restored opposition was graded as good in these 3 hands. We conclude that EMG provides meaningful guidance in selecting optimal forearm muscles for tendon transfers to hands in the setting of slowly progressive polyneuropathies.

Identifying and overcoming barriers to providing sexuality information in the clinical setting

While the scope of the clinician-patient relationship in rehabilitation includes the opportunity to provide information on sexuality, all too often this does not occur. This article identifies barriers to providing information on sexuality and makes suggestions for overcoming them. At a preconference workshop, "Sexuality After Spinal Cord Injury: Understanding the Effects of Knowledge and Attitude on Dissemination Practices," held during the Association of Rehabilitation Nurses 22nd Annual Educational Conference, participants explored barriers to providing sexuality information to their patients and ways for nurse managers and staff members to ameliorate their own discomfort and that of their patients. The barriers identified included lack of time, lack of knowledge, personal attitudes about sexuality, and patient lack of readiness. Approaches that can improve the comfort levels of nurse managers and staff include using educational films and written materials, conducting role playing to explore typical patient questions, and initiating conversation about sexuality with patients. Participants' suggestions for increasing patient comfort level included adopting an open and nonjudgmental listening mode, distinguishing between the physical and emotional aspects of sexual issues, and promoting peer counseling.

Placental membrane fatty acid-binding protein preferentially binds arachidonic and docosahexaenoic acids

To elucidate further the role of placental membrane fatty acid-binding protein (p-FABPpm) in preferential transfer of maternal plasma long chain polyunsaturated fatty acids (LCPUFA) across the human placenta, direct binding of the purified protein with various radiolabelled fatty acids (docosahexaenoic, arachidonic, linoleic and oleic acids) was investigated. Binding of these fatty acids to the protein revealed that p-FABPpm had higher affinities and binding capacities for arachidonic and docosahexaenoic acids compared with linoleic and oleic acids. The apparent binding capacities (Bmax) values for oleic, linoleic, arachidonic and docosahexaenoic acids were 2.0 +/- 0.14, 2.1 +/- 0.17, 3.5 +/- 0.11, 4.0 +/- 0.10 mol per mol of p-FABPpm whereas the apparent dissociation constant (Kd) values were 1.0 +/- .0.07, 0.73 +/- 0.04, 0.45 +/- 0.03 and 0.4 +/- 0.02 microM, respectively (n=3). In the case of human serum albumin, the Kd and Bmax values for all fatty acids were around 1 microM and 5 mol/mol of protein, respectively. These data provide direct evidence for the role of p-FABPpm in preferential sequestration of maternal arachidonic and docosahexaenoic acids by the placenta for transport to the fetus by virtue of its preferential binding of these fatty acids.

Differential distribution and metabolism of arachidonic acid and docosahexaenoic acid by human placental choriocarcinoma (BeWo) cells

The time course of incorporation of [14C]arachidonic acid and [3H]docosahexaenoic acid into various lipid fractions in placental choriocarcinoma (BeWo) cells was investigated. BeWo cells were found to rapidly incorporate exogenous [14C]arachidonic acid and [3H] docosahexaenoic acid into the total cellular lipid pool. The extent of docosahexaenoic acid esterification was more rapid than for arachidonic acid, although this difference abated with time to leave only a small percentage of the fatty acids in their unesterified form. Furthermore, uptake was found to be saturable. In the cellular lipids these fatty acids were mainly esterified into the phospholipid (PL) and the triacyglycerol (TAG) fractions. Smaller amounts were also detected in the diacylglycerol and cholesterol ester fractions. Almost 60% of the total amount of [3H]Docosahexaenoic acid taken up by the cells was esterified into TAG whereas 37% was in PL fractions. For arachidonic acid the reverse was true, 60% of the total uptake was incorporated into PL fractions whereas less than 35% was in TAG. Marked differences were also found in the distribution of the fatty acids into individual phospholipid classes. The higher incorporation of docosahexaenoic acid and arachidonic acid was found in PC and PE, respectively. The greater cellular uptake of docosahexaenoic acid and its preferential incorporation in TAG suggests that both uptake and transport modes of this fatty acid by the placenta to fetus is different from that of arachidonic acid.

Interaction of free fatty acids with human leptin

Relatively high concentrations of leptin are present in plasma and it is thought to play a major role in lipid homeostasis. Leptin is reported to lower tissue triglyceride content by increasing intracellular oxidation of free fatty acids (FFA). However very little is known regarding the interaction between leptin and plasma FFA. We studied the interaction of FFA with leptin using a direct radiolabelled fatty acid binding assay, a fluorescence assay, electrophoretic mobility and autoradiobinding. All these data indicate that binding of FFA with leptin is reversible and shows a positive co-operativity. The binding of FFA to leptin produces a change in the pI value of the leptin and also increased the electrophoretic mobility of the protein in native polyacrylamide gels. The change in leptin's electrophoretic mobility depends on the chain length and the number of double bonds of the fatty acid, as stearic acid, 18:0, had no effect whereas oleic acid, 18:1n-9, linoleic acid, 18:2n-6, arachidonic acid, 20:4n-6, and docosahexaneoic acid, 22:6n-3, affected leptin's mobility to different degrees. The physiological implication of leptin-FFA interaction is not known, however the interaction may depend on the plasma FFA composition and concentration which are known to vary in different pathological/physiological conditions.

Uptake of long chain fatty acids by human placental choriocarcinoma (BeWo) cells: role of plasma membrane fatty acid-binding protein

In order to understand the mechanisms by which fatty acids are taken up by the placenta, the uptake of oleic, linoleic, arachidonic, and docosahexaenoic acids by cultured human placental choriocarcinoma (BeWo) cells was examined. Fatty acid uptake by BeWo cells was temperature-dependent and exhibited saturable kinetics. Oleic acid was taken up least and docosahexaenoic acid most by these cells. Moreover, competitive studies of fatty acid uptake by BeWo cells also indicated preferential uptake compared with oleic acid in the order of docosahexaenoic acid, arachidonic acid, and linoleic acid. Western blot analysis demonstrated that BeWo cells express a protein immunoreactive with antibodies to the human placental plasma membrane fatty acid-binding protein (p-FABPpm). Furthermore, pre-treatment of BeWo cells with these antibodies inhibited most of the uptake of docosahexaenoic (64%) and arachidonic acids (68%) whereas oleic acid uptake was inhibited only 32% compared with the controls treated with preimmune serum. These results clearly demonstrate that the pFABPpm may be involved in the preferential uptake of essential fatty acids (EFA) and their long chain polyunsaturated fatty acids (LCPUFA) by these cells. Studies on the distribution of radiolabeled fatty acids in the cellular lipids of BeWo cells showed that docosahexaenoic acid was incorporated mainly in the triacylglycerol fraction, followed by the phospholipid fraction, whereas for arachidonic acid the reverse was true. The preferential incorporation of docosahexaenoic acid into triacylglycerol suggests that triacylglycerol may play an important role in the placental transport of docosahexaenoic acid to the fetal circulation. Together these results demonstrate the preferential uptake of EFA/LCPUFA by BeWo cells that is most probably mediated via the pFABPpm. We thus propose that the p-FABPpm may be involved in the sequestration of maternal plasma LCPUFA by the placenta.

Cutting the Gordian knot: a two-part approach to the evaluation and professional development of residents

There is chronic dissatisfaction among both faculty and students about the process and effectiveness of resident performance evaluation. The author asserts that the source of this problem is the current practice of merging the two different purposes for evaluation: to monitor residents' meeting of performance standards and to provide guidance for residents' professional development. By attempting to meet both quality-control and guidance obligations using one set of objective data, most residency programs fall short in meeting one of these aims. The common preoccupation with psychometric precision, objectivity, and the statistical processing of forms frequently distracts users from making effective use of evaluation information. The proposed solution is to divide resident evaluation into two simpler, entirely separate and distinct systems--neither of which would look much like the current system. There would be a faculty-controlled, quality-control system focused on screening for minimal performance standards. This would use simple, qualitative measures for early warning and rapid follow-up. The second evaluation system would be a resident-controlled, guidance-oriented system focused on self-assessment, peer and faculty coaching, and reflection. The hypothesized benefits of this approach include an improvement in residents' motivation and performance, an increase in residents' self-direction, and an enhancement of communication between residents and faculty members.

The gene for hereditary sensory neuropathy type I (HSN-I) maps to chromosome 9q22.1-q22.3

Hereditary sensory neuropathy type I (HSN-I, also known as hereditary sensory and autonomic neuropathy type I (HSAN-I), or hereditary sensory radicular neuropathy) is an autosomal dominant disorder that is the most common of a group of degenerative disorders of sensory neurons. HSN-I was initially recognized as a disease that produced mutilating ulceration leading to amputation of digits (Fig. 1). It was given names such as familial ulcers with mutilating lesions of the extremities and perforating ulcers with osseous atrophy. The disease involves a progressive degeneration of dorsal root ganglion and motor neurons, leading to distal sensory loss and later distal muscle wasting and weakness and variable neural deafness. Sensory deficits include loss of all modalities, particularly loss of sensation to pain and temperature. Skin injuries may lead to chronic skin ulcers, osteomyelitis, and extrusion of bone fragments, especially the metatarsals. Onset of symptoms is in the second or later decades. We undertook a genome screen using linkage analysis in four Australian HSN-I kindreds. We now show that the HSN1 gene maps to an 8-centiMorgan (cM) region flanked by D9S318 and D9S176 on chromosome 9q22.1-q22.3. Multipoint linkage analysis suggests a most likely location at D9S287, within a 4.9-cM confidence interval.

Prevalence and origin of de novo duplications in Charcot-Marie-Tooth disease type 1A: first report of a de novo duplication with a maternal origin

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy. Sporadic cases of CMT have been described since the earliest reports of the disease. The most frequent form of the disorder, CMT1A, is associated with a 1.5-Mb DNA duplication on chromosome 17p11.2, which segregates with the disease. In order to investigate the prevalence of de novo CMT1A duplications, this study examined 118 duplication-positive CMT1A families. In 10 of these families it was demonstrated that the disease had arisen as the result of a de novo mutation. By taking into account the ascertainment of families, it can be estimated that > or = 10% of autosomal dominant CMT1 families are due to de novo duplications. The CMT1A duplication is thought to be the product of unequal crossing over between parental chromosome 17 homologues during meiosis. Polymorphic markers from within the duplicated region were used to determine the parental origin of these de novo duplications in eight informative families. Seven were of paternal and one of maternal origin. This study represents the first report of a de novo duplication with a maternal origin and indicates that it is not a phenomenon associated solely with male meioses. Recombination fractions for the region duplicated in CMT1A are larger in females than in males. That suggests that oogenesis may be afforded greater protection from misalignment during synapsis, and/or that there may be lower activity of those factors or mechanisms that lead to unequal crossing over at the CMT1A locus.

Preferential uptake of long chain polyunsaturated fatty acids by isolated human placental membranes

Fatty acid uptake by the placenta is thought to be a carrier-mediated process, however the mechanism by which long chain polyunsaturated fatty acids (LCPUFA) are preferentially accumulated from the maternal circulation to the fetal tissues is still unclear. To examine the role of the placenta in this process, binding of four different radiolabelled fatty acids (-14C-oleate, -14C-linoleate, [14C]a-linolenate and [14C]arachidonate) to human placental membranes was studied. Binding of fatty acid was found to be time- and temperature dependent. At equilibrium, the total binding of oleate was highest (5.1 +/- 0.1 nmoles/mg protein) followed by linoleate (2.8 +/- 0.31 nmoles/mg protein) and arachidonate (2.06 +/- 0.4 nmoles/mg protein) and alpha-linolenate binding was lowest (0.5 +/- 0.1 nmoles/mg protein). However, oleate had the lowest specific binding (37% of the total binding) whereas arachidonate had the highest specific binding (approximately 86% of the total binding) followed by linoleate and a-linolenate (62%, and 69% of the total binding, respectively). Binding of each [14C] fatty acid was also assessed in the presence of 20-fold excess of other unlabelled ligands. Binding sites seem to have preference for the binding of [14C] fatty acids in the following order: arachidonic acid >>> linoleic acid >> a-linolenic acid >>>>> oleic acid, whereas BSP and a-tocopherol did not show any competition with any of the [14C] fatty acids. These data suggest that the fatty acid binding sites in placental membranes are specific for the fatty acids but that they have heterogeneous affinities. Trans fatty acids (elaidic and linoelaidic acids) also competed very strongly for the [14C] fatty acid binding. Polyclonal antiserum raised against placental FABPpm inhibited binding of these [14C] fatty acids but with variable degrees of inhibition; EFA/LCPUFA binding was much more than that of oleate. Our data suggest that EFA/LCPUFA bound to albumin are preferentially transported by human placental membranes and that the placental FABPpm may be involved in the sequestration of EFA/LCPUFA by the placenta.

Plasma membrane fatty-acid-binding protein in human placenta: identification and characterization

A plasma membrane fatty-acid-binding protein (FABPpm) with a molecular mass of approximately 40 kDa has been identified in human placenta. Binding of both [14C] oleate and [14C] linoleate to human placental membranes was found to be time and temperature dependent. Sulphobromophthalein and alpha-tocopherol did not show competition with the [14C] fatty acid binding. These data suggest that the binding sites are specific for fatty acids. incubation of the membranes with trypsin reduced fatty acid binding activity, indicating that the binding sites were protein in nature. A FABPpm was then solubilized from placental membranes and purified to electrophoretic homogeneity. The fatty acid binding activity of the purified protein was confirmed by autoradioblotting. Polyclonal antiserum raised to FABPpm reduced fatty acid binding to placental membrane significantly compared with preimmune serum. The pI value and the amino acid composition of the protein suggest that the placental FABPpm is different from the previously identified hepatic FABPpm.

Characterization of a novel alpha-tocopherol-binding protein from bovine heart cytosol

We previously reported the identification of a new alpha-tocopherol-binding protein (approximately 15 kDa) in the cytosol of rat liver and heart and in rabbit heart (A.K. Dutta-Roy et al., J. Nutr. Biochem. 5, 562-570, 1994). This protein specifically binds alpha-tocopherol and enhances its transfer between separate membranes. In the present paper we have purified and characterized the alpha-tocopherol-binding protein from bovine heart cytosol and compared its various structural and functional properties with the similar size (approximately 15 kDa) cytosolic fatty acid-binding protein of this tissue. alpha-Tocopherol-binding protein was purified to electrophoretic homogeneity from bovine heart cytosol by a procedure involving precipitation with 70% ammonium sulfate, followed sequentially by gel filtration chromatography and chromatofocusing. The purified protein migrated as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent molecular mass of 16 kDa. Isoelectric focusing of the purified protein showed that the pI value is around 4.5. The binding of alpha-tocopherol to the purified protein was rapid, reversible, and saturable. The alpha-tocopherol-binding protein did not bind oleate as assessed by direct radiolabeled fatty acid binding and fluorescence enhancement assay. Amino acid analysis showed the presence of a large number of Ala, Gly, Ser, Lys, and Pro residues and a lesser number of aromatic residues in this protein. Anti-bovine heart fatty acid-binding protein antibody did not recognize the alpha-tocopherol-binding protein in the Western blot. The Western blot, ligand affinity, molecular size, and amino acid analysis data suggest that the alpha-tocopherol-binding protein is different from the cytosolic fatty acid-binding protein and that it may be involved in intracellular transport and metabolism of alpha-tocopherol.

Plasma membrane fatty acid-binding protein (FABPpm) of the sheep placenta

Fatty acid-binding protein (FABPpm) has been identified and characterised from sheep placental membranes. Binding of [14C]oleate to placental membranes was found to be time- and temperature-dependent. Addition of a 20-fold excess unlabelled oleic, palmitic, or linoleic acid reduced the binding of [14C]oleate to the membranes to around 50% of total binding, whereas D-alpha-tocopherol at similar concentrations did not affect [14C]oleate binding. This indicates that the binding sites are specific to fatty acids. Specific binding of [14C]oleate was reduced by heat denaturation or trypsin digestion of the membranes, suggesting that the fatty acid-binding sites are protein in nature. FABPpm was then solubilised from sheep placental membranes, and subsequently purified to electrophoretic homogeneity using an oleate-agarose affinity column. The purified FABPpm had an apparent molecular mass of 40 kDa, as determined by SDS-PAGE and by gel permeation chromatography. The [14C]oleate-binding activity of the purified protein was also confirmed by PAGE followed by autoradioblotting. The specific binding for oleate was around 1.5 nmol per mg of membrane protein. Our data indicate the presence of FABPpm in sheep placental membranes.

Identification of a low molecular mass (14.2 kDa) alpha-tocopherol-binding protein in the cytosol of rat liver and heart

An alpha-tocopherol-binding protein (TBP) with a molecular mass of 14.2 kDa has been identified from the cytosol of rat heart and liver and purified to electrophoretic homogeneity by precipitation with 70% ammonium sulphate, followed by gel filtration and ion-exchange chromatography. In addition to the 14.2 kDa TBP, liver also contains the previously described 30 kDa TBP. The concentrations of the 14.2 kDa TBP in heart and liver were 12.3 micrograms and 17.5 micrograms per g of tissue, respectively. The purified protein specifically binds d alpha-tocopherol in preference to the delta- and gamma-homologues but does not bind oleate. The TBP stimulated the transfer of d alpha-tocopherol from liposomes to mitochondria in vitro by 8-10 fold. These results suggest that low molecular mass TBPs may play a role in intracellular vitamin E transport.

A prerogatives-based model for assessing and managing the resident in difficulty

This paper describes a comprehensive, well-tested approach to managing residents with vexing noncognitive performance and attitudinal difficulties. Frustrations surrounding such cases often stem from inadequately defining and acknowledging the boundaries of faculty and resident prerogatives. Conceptual order is brought to these ill-structured problems by dividing nonroutine assessment into two cycles; a work-up cycle for suspected problems in which the resident is the primary decision maker, and a probation cycle for more serious issues in which faculty are the primary decision makers. By replacing adversarial positioning with a "let's find out" approach, the model encourages faculty to raise suspected issues early while supporting resident autonomy and professional responsibility. Finally, it recognizes the absolute discretion of faculty to judge trainee performance, to impose special requirements, or to terminate a resident's contract for cognitive or noncognitive deficiencies. Application of the model is illustrated through sample dialogues.

Purification and partial characterisation of an alpha-tocopherol-binding protein from rabbit heart cytosol

An alpha-tocopherol-binding protein has been isolated and purified from rabbit heart cytosol. The purified protein had an apparent molecular mass of 14,200, as derived from SDS-PAGE. The content of the protein in rabbit heart was around 11.8 micrograms per g of tissue. The binding of alpha-tocopherol to the purified protein was rapid, reversible, and saturable. Neither gamma nor delta tocopherol could displace the bound alpha-tocopherol from the protein, suggesting a high specificity for alpha-tocopherol. alpha-Tocopherol-binding protein did not bind oleate. Transfer of alpha-tocopherol from liposomes to mitochondria was stimulated 8-fold in the presence of the binding protein, suggesting that this protein may be involved in the intracellular transport of alpha-tocopherol in the heart.

Self-assessment programs and their implications for health professions training

Although expected of all health professionals, self-assessment skills are seldom addressed directly in training. A previous review by the author identified curricular criteria associated with improved accuracy and validity in self-assessments of knowledge and performance in curriculum studies published between January 1970 and February 1990. The present review analyzed 11 studies that meet those criteria. Eight studies were of implementations of self-assessment components within training programs in the health professions, and three involved other training environments. Most described initial disorientation or opposition on the part of learners, attributed to unfamiliar roles and to learners' distrust. The curricula that successfully negotiated the transition to self-assessment norms reported noncognitive benefits such as improvements in morale, motivation, and communications among learners and faculty. Reported cognitive benefits included improvements in knowledge, performance, and self-analysis of performance. The constellation of effects suggests that effective self-assessment programs may promote more mature, collegial, and productive learning environments, particularly suited to the training of health professionals. Most curricula fostering effective self-assessment did not require extraordinary resources, and none jeopardized traditional standards. No evidence was found to support or challenge the expectation that self-assessment training would transfer to later work settings.

The effects of propionate and butyrate on acetate metabolism in rat hepatocytes

1. Two mM propionate or butyrate inhibited the mitochondrial uptake of acetate by rat hepatocytes. 2. With propionate the inhibition was so strong that the net formation of acetate in the cytoplasm, usually masked by the mitochondrial uptake, appeared directly as a net output of acetate into the medium; showing that this net formation of acetate, reported by [Crabtree B., Gordon M.-J. and Christie S. L. (1990) Biochem. J. 270, 219-225] is not an artefact arising from a misinterpretation of isotopic data. 3. The results also suggest that propionate and butyrate inhibit peroxisomal metabolism.

Percutaneous localization of pulmonary nodules for thoracoscopic lung resection

A limiting factor in removing pulmonary nodules by videothoracoscopic techniques is the inability to locate lesions deep within the substance of the lung. We describe a technique in which a hook wire commonly used to localize nonpalpable breast lesions is placed percutaneously into the lung nodule preoperatively. Using the wire anchored into the lung as a guide, the target lesion can be successfully identified and removed thoracoscopically.

A review of the validity and accuracy of self-assessments in health professions training

Valid self-assessment is fundamental to continuing professional competence but is seldom explicitly taught in health professions training. This review analyzed 18 scholarly articles published between January 1970 and February 1990 (14 articles regarding health professions trainees, and four concerning college students or graduate trainees) in which it was possible to compare performance as self-assessed by trainees with performance as assessed by experts or objective tests. The validity of self-assessed performance was found to be low to moderate and did not improve with time in conventional health professions training programs. Self-assessed performance seemed closely related to generalized self-attributions and was minimally influenced by external feedback in the form of test scores, grades, or faculty assessments. In five programs emphasizing explicit self-assessment goals and training strategies, moderate-to-high validity outcomes or improvements over time were demonstrated. Much of what passes for self-assessment in training seems the exercise of an underdeveloped skill, but effective training to improve validity and accuracy is available and feasible.

Protocol for resolving protein mixtures in capillary zone electrophoresis

The separation of protein mixtures by capillary zone electrophoresis can be plagued by wall adsorption of the protein components, causing peak broadening and distortion. A method is presented for overcoming this problem by adding ethylene glycol to the protein sample and by choosing the running buffer and protein sample to be at different pH values and molarities. This protocol appears to work for a wide class of proteins having different molecular weights and pI values. The method has been applied to the analysis of proteins in human serum. Compared to the traditional method of agarose gel electrophoresis, the present method is more rapid and offers better resolution, suggesting its potential as a clinical diagnostic of certain disease states.

pH-balanced solutions with superoxide dismutase (SOD): an attempt to increase island groin flap survival in rats

Balanced salt solution (BSS) and balanced salt solution plus (BSS+), alone and in combination with heparin or superoxide dismutase (SOD), were used as irrigation solutions for rat groin flaps after prolonged ischemia. SOD always improved flap survival when it was present in solution, although when combined with BSS and BSS+, it was less effective than when combined with Ringer's lactate. The physiological pH solutions BSS and BSS+ had no advantages over Ringer's lactate in any of the tested combinations.

The relationship of family dynamics/social support to patient functioning in IDDM patients on intensive insulin therapy

A 6 month pilot study was conducted to examine the relationship between family dynamics/social support and patient functioning in diabetic patients on intensive insulin therapy. Intensified therapy was associated with improvements in the DUHP symptom score, MHI psychological well-being score, and in the DUHP social functioning score. In diabetic patients, regardless of therapy, extreme family dynamics were correlated with higher DUHP symptom scores and lower MHI psychological well-being scores at the initial measurement time. However, over the 6 month study period, extreme family dynamics were predictive of improvements in the DUHP symptoms score and in the quality of friendships in diabetic patients on intensive insuline therapy. In diabetic patients, regardless of therapy, higher levels of social support correlated with higher levels of psychological and social functioning at the initial measurement time, and with improvements in quality of family life over the 6 month measurement time. Higher social support was also associated with improvements in quantity of friends and the DUHP social functioning score in diabetic patients on intensive insulin therapy. The study also generated empiric support for co-evolutionary models of disease states/family dynamics/treatment systems by showing that 6 month changes in family dynamics were predicted by the initial FACES adaptability measure and the initial mean monthly glucose value. Intensified therapy predicted lower family cohesion and more family rigidity over the 6 month study period. These findings also suggest, when combined with the result that diabetic patients from more cohesive families experienced a rise in monthly mean glucose values, that some diabetic patients may become trapped in a vicious cycle which perpetuates poor glucose control and extreme family dynamics.

Comparison of high-frequency oscillatory ventilation and high-frequency jet ventilation in cats with normal lungs

Four adult cats received alternating high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) at equivalent proximal airway pressures. Physiologic measurements were made before and after each ventilator change. Proximal airway pressures were then adjusted as necessary to reestablish normal pH and PaCO2 values. Aortic, pulmonary artery, and central venous pressures were monitored. Cardiac outputs were measured. Pulmonary and systemic vascular resistance, intrapulmonary shunt, and alveolar-arterial oxygen gradient were determined. Following the change from HFOV to HFJV at similar proximal airway pressures, HFJV always produced higher pH values (P less than 0.0001), higher PaO2 values (P less than 0.05), lower PaCO2 values (P less than 0.0001), as well as higher cardiac outputs (P less than 0.01), lower pulmonary artery pressures (P less than 0.001), and lower pulmonary vascular resistances (P less than 0.001). Following the reciprocal crossover, from HFJV to HFOV, HFJV pH values were again higher (P less than 0.001), and PaCO2 values were again lower (P less than 0.001). A comparison of HFOV and HFJV at similar pH and PaCO2 values showed that HFOV consistently required higher peak inspiratory pressures (P less than 0.001), higher mean airway pressure (P less than 0.001), and higher pressure wave amplitudes (P less than 0.001). Under the circumstances of this study, HFJV produced better gas exchange at lower proximal airway pressures.

Capillary Electrophoresis

Electrophoretic separations carried out in capillary tubes offer the possibilities of rapid and automated analyses of small volumes of complex mixtures with unprecedented resolution and sensitivity. Some emerging developments of this new instrumentation are reviewed.