p75LNGFR regulates Trk signal transduction and NGF-induced neuronal differentiation in MAH cells

We have examined NGF-induced signal transduction events and neuronal differentiation in MAH cells, a neuronal progenitor cell line, in which the expression of the two NGF receptors, p140trk (Trk) and p75LNGFR (p75), has been independently manipulated. Coexpression of a large molar excess of p75 substantially enhances the NGF-induced tyrosine autophosphorylation of Trk, compared with cells expressing Trk alone. MAH cells expressing both Trk and p75 stop dividing and acquire a mature neuronal morphology more rapidly and with greater efficiency than MAH cells expressing Trk alone. These biochemical and biological influences of p75 are not observed using a mutant form of NGF that binds Trk but not p75. These data provide evidence that p75 can modulate signal transduction through Trk in a neuronal progenitor cell context and that such modulation has functional consequences for the neuronal differentiation pathway induced by NGF.

Silicon ribbon cables for chronically implantable microelectrode arrays

This paper describes the design, fabrication, and testing of miniature ultraflexible ribbon cables for use with micromachined silicon microprobes capable of chronic recording and/or stimulation in the central nervous system (CNS). These interconnects are of critical importance in reliably linking these microelectrodes to the external world through a percutaneous connector. The silicon cables allow the realization of multilead, multistrand shielded local interconnects that are extremely flexible and yet strong enough to withstand normal handling and surgical manipulation. Cables 5 microns thick, 1-5 cm long, and from 60 to 250 microns wide have been fabricated with up to eight leads. The series lead resistance is typically 4 k omega/cm for polysilicon and 500 omega/cm for tantalum, with shunt capacitance values of 5-10 pF/cm and an interlead capacitance below 10 fF/cm. Soak tests in buffered saline performed under electrical and mechanical stress have been underway for over three years and show subpicoampere leakage levels. Silicon microprobes with built-in ribbon cables have remained functional for up to one year in the guinea pig CNS, recording driven single-unit activity and maintaining impedance levels in the 1-7 M omega range.

Diagnosis of pulmonary complications associated with lung transplantation in children: value of CT vs histopathologic studies

OBJECTIVE

The purpose of this study was to compare the CT findings with those of histopathologic studies to determine if CT can be used to differentiate between the pulmonary parenchymal complications that occur in children after lung transplantation.

MATERIALS AND METHODS

Seventeen children who underwent 14 bilateral and three single lung transplantations were studied. The study population included nine girls and eight boys 2-16 years old (mean, 11 years). CT scans were examined for evidence of interlobular septal thickening, air-space consolidation, ground-glass opacities, nodules, bronchial dilatation, decreased vascularity, and pleural effusions. Thirty-one histopathologic diagnoses from 25 transbronchial biopsies were available for comparison with CT findings. The final histopathologic diagnoses were acute rejection (n = 10), chronic rejection (n = 6), infection (n = 7), nonspecific findings (n = 4), and no abnormalities (n = 4).

RESULTS

No significant difference was noted in the CT findings in patients with acute rejection, chronic rejection, and infection.

CONCLUSION

In this limited study of children, CT findings were not helpful in differentiating between the different parenchymal pulmonary complications associated with lung transplantation. On the basis of these preliminary findings, we recommend caution in suggesting specific diagnoses based on CT scans without histologic proof.

Nicotinic receptor binding of [3H]cytisine, [3H]nicotine and [3H]methylcarbamylcholine in rat brain

Three radiolabeled nicotinic receptor agonists were examined for their binding characteristics and for inhibition by cholinergic compounds in order to distinguish possible differential affinities for subtypes of neuronal nicotinic acetylcholine receptors. KD and Bmax values for [3H]cytisine, [3H]methylcarbamylcholine and [3H]nicotine were determined from Scatchard analysis using an enriched whole-brain membrane fraction from male Sprague-Dawley rats. Respective KD values were 0.15, 1.07 and 0.89 nM while Bmax values were 99, 64 and 115 fmol/mg protein respectively. All three ligands fit a one-site model of receptor-ligand interaction. Concentration-inhibition curves were used to determine Ki values for 16 cholinergic compounds. The rank order of potencies for displacement of the three ligands was: (-)-cytisine > (-)-nicotine > (-)-lobeline = methylcarbamylcholine > 1,1-dimethyl-4-phenylpiperazinium, (+)-nicotine, dihydro-beta-erythroidine, (+/-)-nornicotine > carbachol > arecoline >> oxotremorine, tetrahydroaminoacridine, AF102B >> (-)-cotinine > RS86 = heptylphysostigmine. Correlations of the affinities of these compounds determined with the three ligands were very near to unity. In contrast, there was a negative correlation of affinities for [3H]cytisine compared to affinities for the muscarinic receptor agonist, [3H]oxotremorine-M, and the muscarinic receptor antagonist, [3H]quinuclidinyl benzoate. Using membranes from whole rat brain yields data suggesting that all three nicotinic ligands bind to the same nicotinic acetylcholine receptor subtype, and are unable to distinguish subtypes of neuronal nicotinic acetylcholine receptor at the level examined.

Use of the translational mobility of a plasma membrane protein to assess fertilization of mouse oocytes and viability of mouse zygotes and two-cell embryos

The fluorescence photobleaching recovery (FPR) technique was used to measure the translational mobility of a glycoprotein recognized by the monoclonal antibody (mAb) S75 in plasma membranes of mouse oocytes, zygotes, and two-cell embryos. Glycoprotein fractional mobility (f) was significantly decreased in membranes of unfertilized oocytes compared to zygotes or two-cell embryos (f values, 46 +/- 2 and 65 +/- 2%, respectively; p < 0.0001). Reduced apparent glycoprotein mobility was also observed in morphologically degenerated zygotes and two-cell embryos compared to viable zygotes and two-cell embryos (f values, 8 +/- 1 and 60 +/- 3%, respectively; p < 0.0001). These results indicate that the FPR technique can be used to assess oocyte fertilization and preimplantation embryonic viability. This method may be useful in the evaluation of embryonic viability following in vitro fertilization and in the detection of toxic effects of novel compounds on embryonic development.

Effects of cytokines on epidermal growth factor receptor expression by malignant trophoblast cells in vitro

Trophoblastic cells abundantly express epidermal growth factor (EGF) receptors, which, when activated by EGF or transforming growth factor-alpha, can influence cellular growth and metabolism. Various lymphocyte and macrophage cytokines have been found to influence the proliferation of human choriocarcinoma (CCA) cells in vitro. In the current study we investigated the possibility that certain cytokine effects are mediated by changes in EGF receptor expression. JEG-3 human CCA cells were incubated with varying concentrations of interleukin 1-alpha (IL-1 alpha), interleukin 1-beta (IL-1 beta), interleukin 2, gamma-interferon, granulocyte-macrophage colony stimulating factor and tumor necrosis factor-alpha (TNF), and the expression of EGF receptor was measured by radioimmunoassay using a murine monoclonal antibody with specificity for the EGF receptor. Proliferative or growth suppressive effects of the cytokines were assessed by quantitative analysis of the DNA in the cell culture wells. Macrophage-derived cytokines IL-1 alpha, IL-1 beta and TNF significantly suppressed cell growth; this was associated with a significant increase in EGF receptor expression. The other cytokines had no significant effect on either EGF receptor expression or cell growth. We also studied the expression of EGF mRNA in JEG-3, Jar and BeWo CCA cell lines. By reverse transcription followed by polymerase chain reaction, low levels of EGF mRNA were detected in all three cell lines. Therefore, EGF may be synthesized by JEG-3, Jar and BeWo CCA cell lines to participate in an autocrine growth pathway. Our findings support the concept that cytokines may act as paracrine mediators of autocrine processes involved in CCA cell growth regulation by modulating growth factor receptor expression.

Short-term effects of smoking marijuana on balance in patients with multiple sclerosis and normal volunteers

A double-blind randomized placebo-controlled study of inhaled marijuana smoke on postural responses was performed in 10 adult patients with spastic multiple sclerosis (MS) and 10 normal volunteers matched as closely as possible for age, sex, and weight. A computer-controlled dynamic posturographic platform with a video line scan camera measured shoulder displacement in response to pseudorandom platform movements. Premarijuana smoking patient tracking was inferior to that of the normal volunteers as indicated by the higher noise variance of the former. Smoking one marijuana cigarette containing 1.54% delta 9-tetrahydrocannabinol increased postural tracking error in both the patients and normal control subjects with both eyes open and closed; this untoward effect was greatest for the patients. The tracking error was also accompanied by a decrease in response speed for the patients with their eyes closed. Marijuana smoking further impairs posture and balance in patients with spastic MS.

Cytokine regulation of trophoblast steroidogenesis

Activated monocytes and lymphocytes secrete cytokines that act as autocrine and paracrine mediators to promote and regulate local immune processes. These cell types are abundant at the maternal-fetal interface, and cytokines may play a role in pregnancy maintenance or failure. The purpose of this study was to determine the effects of selected monocyte- and lymphocyte-derived cytokines on trophoblast progesterone and estradiol production. JEG-3 choriocarcinoma cells were cultured in supplemented medium alone or in various concentrations of selected recombinant monocyte or lymphocyte cytokines. The cytokines were evaluated both individually and in combination. After 48 h of incubation, the culture supernatant was aspirated and stored at -20 C. Samples were then analyzed for steroid concentration by specific RIAs. Specific interleukin-1 (IL-1)-and tumor necrosis factor (TNF)-neutralizing antibodies were evaluated for their ability to abrogate the cytokine's observed stimulatory effect. To evaluate the physiological relevance of the progesterone-stimulating effect observed with monocyte-derived cytokines, JEG-3 cells were incubated with activated monocyte supernatant or directly cocultured with activated monocytes, and supernatants from these cultures were analyzed for progesterone levels. The monocyte cytokines [IL-1 alpha (5 U/mL), IL-1 beta (5 U/mL), and TNF alpha (1000 U/mL) significantly stimulated trophoblast progesterone production (nanograms per mL): JEG-3 control, 4.1 +/- 0.5; IL-1 alpha, 7.8 +/- 0.9; IL-1 beta, 8.8 +/- 0.5; and TNF alpha 7.2 +/- 0.8 (P < 0.05). Neither the monocyte nor the lymphocyte cytokines altered trophoblast estradiol production. Activated monocyte supernatant and direct JEG-3-monocyte cocultures also significantly stimulated trophoblast progesterone production in vitro. The stimulatory effect of the monocyte-derived cytokines was specific, as demonstrated by neutralization assay. The increased trophoblast progesterone production was not due to enhanced cellular proliferation, but to enhance cellular steroidogenesis, as measured by quantitative DNA analysis. The lymphocyte cytokines (IL-2, interferon-gamma, and granulocyte-macrophage colony-stimulating factor had no effect on trophoblast progesterone production. We conclude that monocyte IL-1 alpha, IL-1 beta, and TNF alpha may regulate trophoblast progesterone production through paracrine effects. Monocyte-trophoblast interactions may be significant in normal pregnancy as well as pregnancy disorders.

Practices of cardiothoracic transplant centers regarding hepatitis C-seropositive candidates and donors

The purpose of this survey was to determine current practices of cardiothoracic transplant centers regarding transplantation of hearts and lungs into hepatitis C (HCV)-seropositive candidates and the use of organs from HCV-seropositive donors. A telephone survey of 48 cardiothoracic transplant centers was conducted in October 1992. Questions included the center's policy for listing HCV-seropositive candidates; if, and under what conditions, organs from HCV-seropositive donors would be used; and which HCV assays were used. Forty-five programs responded; 75% will list an HCV-seropositive candidate, either directly or by lack of routine screening to exclude such patients; only 16% will not accept HCV-seropositive candidates; 9% had no policy. Overall, 69% will accept organs from HCV-seropositive donors, at least for selected recipients (22% for any recipient, 45% for HCV-seropositive and/or status I recipients; 2% do not screen donors). A total of 27% will never accept organs from an HCV-seropositive donor, and 4% had no policy. Thirty centers provided information on HCV methodology. All but one use a second generation ELISA or EIA as a first-line test. A positive result will be followed by a confirmatory assay/liver biopsy in 42%. The variation in practices reflects the ambiguity in the literature. Adequate evaluation of morbidity and mortality due to HCV infection in this population has not yet been possible, although currently available reports do not show a substantial increase. Prospective controlled trials in cardiothoracic transplant patients are necessary.

Mammalian achaete-scute homolog 1 is required for the early development of olfactory and autonomic neurons

The mouse Mash-1 gene, like its Drosophila homologs of the achaete-scute complex (AS-C), encodes a transcription factor expressed in neural precursors. We created a null allele of this gene by homologous recombination in embryonic stem cells. Mice homozygous for the mutation die at birth with apparent breathing and feeding defects. The brain and spinal cord of the mutants appear normal, but their olfactory epithelium and sympathetic, parasympathetic, and enteric ganglia are severely affected. In the olfactory epithelium, neuronal progenitors die at an early stage, whereas the nonneuronal supporting cells are present. In sympathetic ganglia, the mutation arrests the development of neuronal precursors, preventing the generation of sympathetic neurons, but does not affect glial precursor cells. These observations suggest that Mash-1, like its Drosophila homologs of the AS-C, controls a basic operation in development of neuronal progenitors in distinct neural lineages.

Linear quadratic Gaussian control of a deformable mirror adaptive optics system with time-delayed measurements

We present a technique for controlling a ground-based deformable mirror adaptive optics telescope to compensate for optical wave-front phase distortion induced by a turbulent atmosphere. Specifically, a predictive linear quadratic Gaussian (LQG) controller is designed that generates commanded control voltages to the mirror actuators based on a set of time-delayed wave-front slope measurements from a Hartmann-type wave-front sensor.

Sympathetic neuroblasts undergo a developmental switch in trophic dependence

Sympathetic neurons require NGF for survival, but it is not known when these cells first become dependent on neurotrophic factors. We have examined in vitro mitotically active sympathetic neuroblasts immuno-isolated from different embryonic stages, and have correlated this functional data with the expression of neurotrophin receptor mRNAs in vivo. Cells from E14.5 ganglia are supported by neurotrophin-3 (NT-3) in a serum-free medium, but not by NGF; NT-3 acts as a bona fide survival factor for these cells and not simply as a mitogen. By birth, sympathetic neurons are well-supported by NGF, whereas NT-3 supports survival only weakly and at very high doses. This change in neurotrophin-responsiveness is correlated with a reciprocal switch in the expression of trkC and trkA mRNAs by sympathetic neuroblasts in vivo. These data suggest that neurotrophic factors may control neuronal number at earlier stages of development than previously anticipated. They also suggest that the acquisition of NGF-dependence may occur, at least in part, through the loss of receptors for these interim survival factors.

The role of complement component C3b and its receptors in sperm-oocyte interaction

Previous studies have shown that human sperm that have undergone the acrosome reaction express a unique tissue-specific variant of the complement component 3 (C3)-binding molecule membrane cofactor protein (MCP, CD46) and that damaged or dead sperm activate the alternative pathway of complement and bind C3 catabolites. In this study we provide evidence that MCP on sperm that have undergone the acrosome reaction specifically binds dimeric C3b and that human sperm acrosomal proteases released during the acrosome reaction directly cleave C3, facilitating its binding to MCP. Furthermore, human and hamster oocytes can activate the alternative pathway of complement and also bind human C3 fragments. Monoclonal antibodies specific for complement receptors type 1 (CD35) and type 3 (CD11b/CD18) bind to the human oocyte plasma membrane, indicating that specific complement-binding molecules may play a role in the attachment of C3 catabolites to oocytes. Subsaturating concentrations of dimeric C3b (0.01-1 microM) promoted penetration of hamster oocytes by human sperm, whereas saturating doses (> 10 microM) inhibited this process. In addition, antibodies to both MCP and C3 significantly inhibited penetration of hamster oocytes by human sperm. These data provide evidence that regulated gamete-induced generation of C3 fragments and the binding of these fragments by selectively expressed receptors on sperm and oocytes may be an initial step in gamete interaction, leading to membrane fusion and fertilization.

Molecular diversity of the SCG10/stathmin gene family in the mouse

SCG10 is a neuronal growth-associated protein that shares an amino acid sequence similarity with an 18- to 19-kDa phosphoprotein named stathmin (also called p19, p18, Op18, pp17, prosolin, pp20, 19K, and leukemia-associated phosphoprotein, Lap18), which is more broadly expressed in a variety of cell types of the neural, immune, and reproductive systems. The sequence similarity has suggested that SCG10 and stathmin have been derived from structurally and evolutionarily related genes. To explore the structural and evolutionary relationships between these genes, we have isolated a series of cosmid and phage clones that covers the entire region of the mouse stathmin gene and most of the mouse SCG10 gene. The SCG10 transcription unit spans at least 30 kb, while the stathmin gene is 6 kb in length. Both genes consist of five exons, and many of the intron/exon boundaries fall into the homologous regions of conserved domains of these two proteins. However, the promoter-proximal regions are distinct in the two genes, suggesting that they have evolved by fusion of the duplicated coding exons to unique promoters. Southern blot analysis indicates that SCG10 mRNA is encoded by a single gene in the mouse genome, while stathmin cDNA probes detect multiple genes. Chromosome mapping experiments reveal that the SCG10 gene is localized at the proximal region of mouse chromosome 3 and is linked to Il-7, while the stathmin gene loci are distributed to three chromosomes; the authentic stathmin gene lies on chromosome 4, whereas the loci on chromosomes 9 and 17 are likely to be pseudogenes. These data are consistent with the idea that the neuron-specific SCG10 gene evolved by duplication and modification of the more broadly expressed stathmin/Lap18 gene.

Lineage diversification of the neural crest: in vitro investigations

This review addresses the contribution of in vitro investigations to our understanding of neural crest development. Cell culture has been used to study the environmental control of cell lineage decisions in the neural crest and to define the developmental potentials of specific populations of neural crest and neural crest-derived cells. We consider the roles of environmental signals in the context of the development of several different neural crest-derived lineages. We also discuss evidence for influences of local cell-cell interactions and substrate molecules on neural crest development. Data bearing on the issues of neural crest cell multipotency, self-renewal, and lineage commitment are reviewed.

XASH-3, a novel Xenopus achaete-scute homolog, provides an early marker of planar neural induction and position along the mediolateral axis of the neural plate

We have isolated a novel Xenopus homolog of the Drosophila achaete-scute genes, called XASH-3. XASH-3 expression is neural specific and is detected as early as stage 11 1/2, making it one of the earliest markers of neural induction so far described. Moreover, XASH-3 expression within the neural plate is regionally restricted. Transverse bands of XASH-3 mRNA mark discrete positions along the anteroposterior axis, while longitudinal bands mark a discrete position along the mediolateral axis. This latter site of XASH-3 expression appears to demarcate the prospective sulcus limitans, a boundary zone that later separates the functionally distinct dorsal (alar) and ventral (basal) regions of the spinal cord. In sandwich explants lacking any underlying mesoderm, XASH-3 is expressed in longitudinal stripes located lateral to the midline. This provides the first indication that planar or midline-derived inductive signals are sufficient to establish at least some aspects of positional identity along the mediolateral axis of the neural plate. By contrast, the transverse stripes of XASH-3 expression are not detected, suggesting that this aspect of anteroposterior neural pattern is lost or delayed in the absence of vertically passed signals. The restricted mediolateral expression of XASH-3 suggests that mediolateral patterning of the neural plate is an early event, and that this regionalization can be achieved in the absence of inducing signals derived from underlying mesoderm.

MASH genes and the logic of neural crest cell lineage diversification

Avian embryos have traditionally been the system of choice for studying neural crest development, but the combination of reverse genetics and clonal culture should allow new insights to be gained from mammalian systems as well. We describe one of the first examples where a targeted mutation in a developmental control gene, isolated on the basis of its homology to Drosophila neural determination genes, causes a highly selective phenotype affecting the early development of a subset of neural crest derivatives. Detailed analysis of the cellular phenotype and expression pattern of the gene, called MASH-1, have led to novel insights into the genetic logic that controls neural crest development. Most important, some features of the phenotype appear inconsistent with the predictions of current models of neural crest lineage diversification. These unexpected results have forced a reevaluation of our thinking about some aspects of neural crest development, and illustrate the power of the reverse genetic approach to reveal unanticipated features of complex biological systems as well as to suggest new directions for future study.

Environmental factors related to the outcome of panic disorder. A seven-year follow-up study

The purpose of this study was to examine factors related to the outcome of naturalistically treated panic disorder. In order to achieve this we followed up 69 patients 7 years after they had presented at a psychiatric clinic. At follow-up, the patients were generally doing well despite persisting symptoms. Patients who were more severely ill at the time of initial assessment had a worse outcome. These patients had more severe panic and agoraphobic symptoms, had illnesses of longer duration, and more often had histories of major depression. Among the developmental variables examined, separation from a parent by death or divorce was strongly related to poor outcome. Other factors associated with poor outcome included high interpersonal sensitivity, low social class, and unmarried marital status. The findings show that, for this chronic illness, measures of severity and chronicity predict more severe and persisting symptoms. They also indicate that outcome is importantly related to the social environment in which the illness develops and with which it interacts.

Comparison of methods to enumerate white blood cells in semen

Seminal WBC counts obtained by an mAb-based immunohistologic method correlated well with seminal granulocyte counts obtained with a simple peroxidase method (rho = +0.70; P < 0.0001). However, total WBC counts were significantly higher than granulocyte counts for most samples. With the immunohistologic method, 17 of 112 samples (15.2%) contained > 10(6) WBC/mL semen, whereas the peroxidase method resulted in only 10 samples (8.9%) with > 10(6) WBC/mL. When the threshold defining leukocytospermia was set at 1 x 10(6) positive cells/mL for both methods, the specificity of the peroxidase test compared with the immunohistology technique was 100% (10/10), but the sensitivity was only 58.8% (10/17). When the threshold for leukocytospermia in the peroxidase test was lowered to 5 x 10(5) positive cells/mL semen, the sensitivity relative to the immunohistology technique increased to 94.1% (16/17), and specificity remained 100% (16/16). Likewise, good interassay sensitivity and specificity values were obtained with thresholds of 10(6) WBC/mL for the peroxidase assay and 2 x 10(6) WBC/mL for the immunohistology assay. We conclude that either peroxidase or immunohistology assays can be used to screen for leukocytospermia, but that more research is needed to establish thresholds for pathological levels of WBC in semen using these two approaches. Total round cell counts are of no value for enumerating WBC in semen.

Effects of growth factors and growth factor-extracellular matrix interactions on mouse trophoblast outgrowth in vitro

A variety of cell types at the blastocyst implantation site produce growth factors that could play important role(s) in the implantation process. Recent evidence indicates that decidual cells and/or embryos produce transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and colony-stimulating factor (CSF-1). Furthermore, receptors for EGF, PDGF, and CSF-1 have been detected on embryonic and trophoblastic cells. The purpose of this study was to investigate the effects of these growth factors and possibly growth factor-extracellular matrix interactions on mouse blastocyst attachment and trophoblast outgrowth in vitro. Various dilutions of the growth factors TGF-alpha, EGF, PDGF, FGF, and CSF-1 were added to cultures of 5-day-old hatched blastocysts in fibronectin-coated plastic wells. Blastocysts were scored for attachment, trophoblast outgrowth, and surface area at 24, 48, and 72 h. Each of these growth factors significantly enhanced trophoblast outgrowth, and a cocktail containing all of the growth factors had a significantly stronger effect. PDGF and FGF, but no other growth factors, also enhanced trophoblast outgrowth following pulsatile incubation with the fibronectin matrix coating of the culture wells, indicating that interactions between these growth factors and extracellular matrix elements could influence implantation. This study suggests that various growth factors may play an important role in the implantation process, that synergistic effects may be obtained by combinations of growth factors, and that interactions between certain growth factors and extracellular matrix elements may be significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines and growth factors in implantation

A variety of cell types at the blastocyst implantation site produce cytokines and growth factors that could play an important role in the implantation process. Furthermore, receptors for cytokines and growth factors have been detected on embryonic and trophoblastic cells. The purpose of the article is to review the published literature on the effect of cytokines and growth factors on implantation events, and to present recent data from our laboratory on effects of growth factors and cytokines on mouse blastocyst implantation events in vitro.

Pediatric lung transplantation: radiographic-histopathologic correlation

Chest radiographic and histopathologic findings were retrospectively reviewed to determine the spectrum of findings in 16 children who underwent a total of 19 lung transplantations. Radiographs were evaluated for air-space disease, interstitial disease, Kerley B lines, pleural fluid, and cardiac size, and the interval from transplantation to the onset of complications was determined. Radiographic findings were correlated with 62 histopathologic diagnoses obtained from 51 transbronchial and open lung biopsy specimens. The final histopathologic diagnoses were acute rejection (n = 19), chronic rejection (n = 8), infection (n = 11), lymphoproliferative disorder (n = 4), and nonspecific (n = 20). The radiographic patterns of the complications were not significantly different. Seventy-nine percent (15 of 19) of episodes of acute rejection and 64% (seven of 11) of episodes of infection occurred within 5 weeks of transplantation, while 63% (five of eight) of the episodes of chronic rejection occurred after this period. Since chest radiographs are nonspecific, caution should be exercised in basing clinical decisions only on the radiographic pattern in the absence of corroborative clinical and histopathologic findings.

Determination of fibrinogen in plasma by high-performance immunoaffinity chromatography

A high-performance immunoaffinity chromatographic (HPIAC) method for fibrinogen was developed which had several advantages over existing methodologies including increased linear range and no interference from heparin. Several modifications of usual HPIAC procedures were necessary including the employment of a methacrylate polymeric support to reduce non-specific adsorption and the addition of urea to a pH 2.1 elution buffer to affect elution. A significant split-peak effect (i.e., unretained fibrinogen) was noted at higher flow-rates and at higher fibrinogen concentrations, which was shown to be temperature-dependent, with the amount of fibrinogen retained on the column increasing with increased temperature.

High-resolution computer display of portable, digital, chest radiographs of adults: suitability for primary interpretation

OBJECTIVE

The suitability of using a high-resolution computer-display system for primary interpretation of adult chest radiographs obtained with portable apparatus and storage phosphor technology was evaluated with receiver operating characteristic analysis and subjective methods.

MATERIALS AND METHODS

Sixty portable digital chest radiographs showing abnormalities that approached the resolution limits of our computed radiography system were selected. The original digital data making up the 2140 x 1760 x 10 bit images were transferred to a cathode ray tube (CRT) display system composed of two Megascan monitors. Postprocessing rendered two images, one for each monitor, to emulate the two-on-one hard-copy format produced by the computed radiography system. Each image set was interpreted independently by three radiologists experienced with hard-copy format. Limited level and window adjustments were allowed during CRT interpretation. For both CRT and hard-copy display, images were graded on the basis of the interpreter's confidence in the presence of pneumothorax and parenchymal abnormalities. Three types of foreign devices were subjectively analyzed: endotracheal tubes, nasogastric tubes, and temporary epicardial pacer wires.

RESULTS

No significant differences were found in detecting pneumothorax or focal infiltrates. One radiologist found the hard copy better for detecting diffuse infiltrates (p = .02); two radiologists favored CRT for visualizing nasogastric tubes (p < .005, p < .02); and one radiologist favored CRT for visualizing temporary epicardial pacer wires (p = .05).

CONCLUSION

We conclude that an optimized high-resolution CRT system is quite promising for primary interpretation of digital portable chest radiographs, but further investigation and greater statistical power are necessary to confirm our results.

Molecular control of cell fate in the neural crest: the sympathoadrenal lineage

Over the past five years, new insights have been gained into the biology of the SA lineage. These advances have been powered by the development of immunologic methods to isolate embryonic SA progenitors from fetal adrenal glands and sympathetic ganglia. Analysis of these embryonic progenitors has confirmed many of the ideas derived from earlier studies of postnatal cells, but has necessitated several revisions in our thinking, as well. First, embryonic SA progenitors appear to be distinct from mature SIF cells, a cell type initially postulated to be the central intermediate in the SA lineage. Second, FGF, not NGF, appears to be an important early influence on neuronal fate; NGF responsiveness appears relatively late in differentiation. Third, the development of both sympathetic neurons and adrenal chromaffin cells is not a one-step process, but rather involves a series of events, in which the cells change their responsiveness to growth factors and glucocorticoids. Fourth, emerging circumstantial evidence suggests that SA progenitors may have additional developmental potentials. Finally, new insights have been gained into the molecular mechanisms that underlie both the differentiation of SA progenitors and their determination from earlier multipotent neural crest cells. These advances have made the SA progenitor a well-defined system for studying the molecular control of cell fate in a vertebrate neurogenic precursor cell. The analysis of the SA lineage at the cell biological level has raised several interesting molecular questions for future investigation. In the neuronal branch of the SA lineage, how is the acquisition of NGF-responsiveness and NGF-dependence controlled, and what is the relationship of these events to the expression of p140trk and p75? In the chromaffin branch of the pathway, which molecules control the timing of PNMT expression? In the uncommitted SA progenitor, what is the molecular basis of the antagonism between the competing neuronal and chromaffin pathways of differentiation, and how does commitment to neuronal differentiation occur? Can SA progenitors differentiate to enteric neurons in vitro, and which differentiation and survival factors control this phenotype, as well as the other classical neurotransmitter and neuropeptide phenotypes expressed by SA derivatives? What are the roles of MASH1 and other regulatory genes in controlling early stages in neural crest cell determination, and how is the expression of these molecules in turn controlled? How much of the genetic regulatory network controlling neuronal differentiation in Drosophila has been conserved in vertebrates?(ABSTRACT TRUNCATED AT 400 WORDS)