FDG PET-CT imaging of therapeutic response in granulomatous lymphocytic interstitial lung disease (GLILD) in common variable immunodeficiency (CVID).

Common variable immunodeficiency (CVID) is the most common severe adult primary immunodeficiency and is characterized by a failure to produce antibodies leading to recurrent predominantly sinopulmonary infections. Improvements in the prevention and treatment of infection with immunoglobulin replacement and antibiotics have resulted in malignancy, autoimmune, inflammatory and lymphoproliferative disorders emerging as major clinical challenges in the management of patients who have CVID. In a proportion of CVID patients, inflammation manifests as granulomas that frequently involve the lungs, lymph nodes, spleen and liver and may affect almost any organ. Granulomatous lymphocytic interstitial lung disease (GLILD) is associated with a worse outcome. Its underlying pathogenic mechanisms are poorly understood and there is limited evidence to inform how best to monitor, treat or select patients to treat. We describe the use of combined 2-[(18)F]-fluoro-2-deoxy-d-glucose positron emission tomography and computed tomography (FDG PET-CT) scanning for the assessment and monitoring of response to treatment in a patient with GLILD. This enabled a synergistic combination of functional and anatomical imaging in GLILD and demonstrated a widespread and high level of metabolic activity in the lungs and lymph nodes. Following treatment with rituximab and mycophenolate there was almost complete resolution of the previously identified high metabolic activity alongside significant normalization in lymph node size and lung architecture. The results support the view that GLILD represents one facet of a multi-systemic metabolically highly active lymphoproliferative disorder and suggests potential utility of this imaging modality in this subset of patients with CVID.

Influence of glottic aperture on the tracheal flow.

The extra-thoracic mouth-throat area has a major influence on the aerosol delivery to the proximal or peripheral intra-thoracic airways. To characterize the particle deposition in this area, it is important to investigate first the flow structures in this crucial--in relation to the aerosol deposition--region. The glottis, which is delimited by the vocal cords and therefore has the narrowest passage, generates a laryngeal jet and a reverse flow downstream the glottis. It is generally assumed that the glottis has different shapes and cross-sectional areas at different moments during the respiratory cycle and also depends on the average inspiratory flow rate. Therefore, the influence of a circular glottal aperture, with a cross-sectional area of 90 mm2 and an elliptical and triangular shape, both with an area of 45 mm2, on the flow is investigated. However, the area of the circular aperture is twice as big as the area of the elliptical one, it has almost no influence on the flow structures. On the other hand, the triangular glottal aperture shifts the laryngeal jet in the direction of the posterior wall, and generates two pairs of counter rotating secondary vortices downstream the glottis, where the circular and elliptical only aperture generates one pair of vortices. The difference in pressure drop is more dominated by the cross-sectional area than by the shape of the glottis. This suggests the need for rendering geometry of future upper airway models even more realistic as the appropriate three-dimensional (3D) medical imaging techniques are becoming available.

p190 RhoGAP is the principal Src substrate in brain and regulates axon outgrowth, guidance and fasciculation.

The Src tyrosine kinases have been implicated in several aspects of neural development and nervous system function; however, their relevant substrates in brain and their mechanism of action in neurons remain to be established clearly. Here we identify the potent Rho regulatory protein, p190 RhoGAP (GTPase-activating protein), as the principal Src substrate detected in the developing and mature nervous system. We also find that mice lacking functional p190 RhoGAP exhibit defects in axon guidance and fasciculation. p190 RhoGAP is co-enriched with F-actin in the distal tips of axons, and overexpressing p190 RhoGAP in neuroblastoma cells promotes extensive neurite outgrowth, indicating that p190 RhoGAP may be an important regulator of Rho-mediated actin reorganization in neuronal growth cones. p190 RhoGAP transduces signals downstream of cell-surface adhesion molecules, and we find that p190-RhoGAP-mediated neurite outgrowth is promoted by the extracellular matrix protein laminin. Together with the fact that mice lacking neural adhesion molecules or Src kinases also exhibit defects in axon outgrowth, guidance and fasciculation, our results suggest that p190 RhoGAP mediates a Src-dependent adhesion signal for neuritogenesis to the actin cytoskeleton through the Rho GTPase.

The adhesion signaling molecule p190 RhoGAP is required for morphogenetic processes in neural development.

Rho GTPases direct actin rearrangements in response to a variety of extracellular signals. P190 RhoGAP (GTPase activating protein) is a potent Rho regulator that mediates integrin-dependent adhesion signaling in cultured cells. We have determined that p190 RhoGAP is specifically expressed at high levels throughout the developing nervous system. Mice lacking functional p190 RhoGAP exhibit several defects in neural development that are reminiscent of those described in mice lacking certain mediators of neural cell adhesion. The defects reflect aberrant tissue morphogenesis and include abnormalities in forebrain hemisphere fusion, ventricle shape, optic cup formation, neural tube closure, and layering of the cerebral cortex. In cells of the neural tube floor plate of p190 RhoGAP mutant mice, polymerized actin accumulates excessively, suggesting a role for p190 RhoGAP in the regulation of +Rho-mediated actin assembly within the neuroepithelium. Significantly, several of the observed tissue fusion defects seen in the mutant mice are also found in mice lacking MARCKS, the major substrate of protein kinase C (PKC), and we have found that p190 RhoGAP is also a PKC substrate in vivo. Upon either direct activation of PKC or in response to integrin engagement, p190 RhoGAP is rapidly translocated to regions of membrane ruffling, where it colocalizes with polymerized actin. Together, these results suggest that upon activation of neural adhesion molecules, the action of PKC and p190 RhoGAP leads to a modulation of Rho GTPase activity to direct several actin-dependent morphogenetic processes required for normal neural development.

Evidence for distinct mechanisms of transition state stabilization of GTPases by fluoride.

GTPase-activating proteins (GAPs) function by stabilizing the GTPase transition state. This has been most clearly demonstrated by the formation of a high-affinity complex between various GAPs and GDP-bound GTPases in the presence of aluminum tetrafluoride, which can mimic the gamma-phosphate of GTP. Herein, we report that p190 RhoGAP forms a high-affinity complex with Rho GTPases in the presence of fluoride ions, suggesting that p190 also functions to stabilize the GTPase transition state. However, this Rho-p190 complex does not require aluminum ions or even guanine nucleotide, indicating a distinct role for fluoride that is not consistent with the gamma-phosphate-mimicking hypothesis. These results indicate that it is necessary to reconsider the assumed role of fluoride in stabilizing a variety of other GTPase-GAP interactions where the requirement for aluminum or guanine nucleotide has not yet been addressed.

Mediastinoscopy in patients with presumptive stage I sarcoidosis: a risk/benefit, cost/benefit analysis.

STUDY OBJECTIVE: To determine whether persons with asymptomatic bilateral hilar lymphadenopathy (ABHL) and normal results of a physical examination should be observed with a presumptive diagnosis of stage 1 sarcoidosis (S1S) (ABHLps), its most frequent cause, or undergo mediastinoscopy to avoid overlooking an alternative diagnosis (AD) requiring treatment. DESIGN: We surveyed the English-language medical literature to estimate the proportion of persons with tuberculosis (TB), Hodgkin's disease (HD), and non-Hodgkin's lymphoma (NHL) who present with ABHL and calculated the number of mediastinoscopies required to identify each AD by computing the following ratio: incidence S1S/incidence of each AD presenting as ABHL (I(S1S)/I[ABHL-AD]). Risks of mediastinoscopy and benefits of earlier ascertainment of AD were derived from the published literature. Cost estimates were based on institutional charges. We conducted a regional survey of practicing pulmonologists to ascertain their diagnostic preferences. RESULTS: We estimate that if 33,000 persons with ABHL underwent mediastinoscopy, 32,982 (99.95%) would be found to have S1S or, very rarely, a disorder not requiring intervention; 407 would require hospitalization for complications at a cost in excess of $1 million; and 204 would experience major morbidity; 8 persons with TB, 9 with HD, and 1 with NHL would be identified at a cost of $100 to $200 million. The benefit for persons diagnosed as having AD would be minimal and likely offset by the procedural mortality. Seventy percent of pulmonologists responding to the survey favored observation over transbronchial lung biopsy or mediastinoscopy in patients with ABHL. CONCLUSION: A policy of continued observation of patients presenting with ABHL is preferable to diagnostic mediastinoscopy from both the risk/benefit and cost/benefit standpoint.

Rat oxytocin receptor in brain, pituitary, mammary gland, and uterus: partial sequence and immunocytochemical localization.

Partial complementary DNAs of an oxytocin (OT) receptor were cloned from rat brain and uterus. The complementary DNAs encoded for the same amino acid sequence, which showed a high degree of homology with the human and porcine uterine OT receptors, except for a region in the third intracellular loop. Antibodies were raised against nonoverlapping sequences of the third intracellular loop of this rat OT receptor. Using these antisera, OT receptor expression was demonstrated in the brain, pituitary, mammary gland, and uterus by immunocytochemistry. In the brain, several areas including the ventromedial hypothalamus, the bed nucleus of the stria terminalis, the ventral pallidum, the paraventricular nucleus, and the dorsal part of the supraoptic nucleus, demonstrated OT-receptor immunoreactivity. However, no immunoreactivity was detected in two areas of the brain known to contain dense OT-binding sites by receptor autoradiography studies: the ventral hippocampus and the central nucleus of the amygdala. In the pituitary, both the anterior and posterior lobes were positive for OT receptor immunoreactivity, whereas the intermediate lobe was negative. These results demonstrate that the same receptor type is expressed in both peripheral OT target tissues and the brain, and also suggest the possibility that a different OT receptor subtype may be present in some areas of the brain.

Immunocytochemical detection of prostaglandin E2 in microvasculature and in neurons of rat brain after administration of bacterial endotoxin.

The aim of the present study was to identify the site of prostaglandin E2 (PGE2) production in the brain in response to a pyrogenic dose of endotoxin. The presence of PGE2 was detected using immunocytochemistry on Bouin's fixed vibratome sections of control and endotoxin-treated rats. Peripheral administration of endotoxin caused a time-related stimulation of PGE2 immunoreactivity (irPGE2) in the choroid plexus and in the microvasculature of the brain. In addition to these sites, hypophysiotrophic neurons of the paraventricular nucleus (PVN) and supraopticus nucleus (SON) responded with induction of irPGE2 to endotoxin administration. Our data demonstrate that alterations in brain function in response to endotoxin may involve arachidonic metabolites such as PGE2 that are induced at the blood-brain barrier (microvasculature) and blood-liquor barrier (choroid plexus) and in hypophysiotrophic neurons of the rat brain.

Appearance of interleukin-1 in macrophages and in ramified microglia in the brain of endotoxin-treated rats: a pathway for the induction of non-specific symptoms of sickness?

The presence and cellular localization of interleukin-1 beta immunoreactivity (irIL-1) in and around the brain was investigated using immunocytochemistry on Bouin's fixed vibratome brain sections of control and endotoxin-treated rats. Peripheral administration of endotoxin resulted in the appearance of irIL-1 in cells in the meninges, choroid plexus, brain blood vessels and in non-neuronal cells in the brain parenchyma. Using monoclonal and polyclonal antibodies to macrophage and astrocyte antigens, the endotoxin-induced irIL-1 positive cells could be identified as macrophages in the meninges and choroid plexus (ED2), perivascular cells (ED2) and ramified microglial cells (GSA-I-B4 isolectin). Our data demonstrate a pathway for the induction of non-specific sickness symptoms in response to endotoxin.

Treatment of De Quervain's tenosynovitis with corticosteroids. A prospective study of the response to local injection.

Fifty-six cases of De Quervain's tenosynovitis (in 55 patients) were treated with a "long-acting" corticosteroid, methylprednisolone acetate, and followed prospectively over a 4-year period. Approximately 90% of these patients were effectively managed either with a single injection (58%) or with multiple injections (33%) of this compound. Seventeen patients experienced recurrence a mean of 11.9 months after the initial injection. Three had minor flares and were not reinjected; the others responded to reinjections. Ten percent of the cases could not be controlled with local injection, and these patients were referred for surgery. Adverse reactions were self-limited and relatively minor; no tendon ruptures or local infections occurred. We present a discussion of our review of the literature regarding medical therapy and surgical release for this condition. Treatment of De Quervain's tenosynovitis with methylprednisolone acetate injection rapidly controls the signs and symptoms, does not lead to serious adverse reactions, and should be the preferred initial treatment.

Purine metabolism as a target for leukemia chemotherapy.

This article focuses on the chemotherapeutic agents which alter purine metabolism as a means to achieve selective killing of leukemic cells. We present an overview of purine metabolism in order to highlight enzymatic steps which are targeted by antileukemic drugs. Purine antimetabolites used in the treatment of leukemia can be grouped into three classes: (1) structural analogs of normal purines (6-mercaptopurine and 6-thioguanine); (2) inhibitors of de novo purine biosynthesis (methotrexate and hydroxyurea); and (3) inhibitors of purine salvage (2'-deoxycoformycin). In addition, a number of investigational drugs (trimetrexate, fludarabine and 2'-chlorodeoxyadenosine) have been recently introduced and show promise in early clinical trials. Purine antimetabolites are active in a variety of lymphoid and myeloid leukemias and represent an important component of the therapy of these disorders. Several of the drugs have been developed with the specific intent of perturbing enzymes involved in purine metabolism. Refinements in our understanding of purine biochemistry in normal and leukemic cells may aid future efforts to design more effective drugs.