Novel bandlike signal abnormality suggestive of heterotopia in patient with a KCNQ1 frameshift mutation

Malformations of cortical development are associated with epilepsy and cognitive dysfunction, and can occur in patients with SCN1A ion channel mutations. We report a novel and subtle bandlike subcortical heterotopia on integrated positron emission tomography–magnetic resonance imaging ( PET‐MRI) in a patient with treatment‐resistant epilepsy due to a de novo KCNQ1 frameshift mutation. Our case highlights the potential for other channel mutations to cause both epilepsy and cortical malformations. Further scrutiny of high contrast resolution MRI studies is warranted for patients with KCNQ1 and other epilepsy genes to further define their extended phenotype.

A Case of Recurrent Insomnia: Extending the Spectrum of Autoimmune Encephalitis

ABSTRACT

Recurrent insomnia is an uncommon manifestation that is encountered rarely in a sleep clinic. We report a woman with recurrent insomnia due to an autoimmune process that resolved after a course of immunotherapy.

Novel immunological approaches for the treatment of Alzheimer's disease

Alzheimer's disease (AD), the most prevalent form of dementia worldwide, can be deemed as the next global health epidemic. The biochemistry underlying deposition of amyloid beta (A β) and hyperphosphorylated tau aggregates in AD has been extensively studied. The oligomeric forms of A β that are derived from the normal soluble A β peptides are believed to be the most toxic. However, it is the fibrillar Aβ form that aggregates as amyloid plaques and cerebral amyloid angiopathy, which serve as pathological hallmarks of AD. Moreover, deposits of abnormally phosphorylated tau that form soluble toxic oligomers and then accumulate as neurofibrillary tangles are an essential part of AD pathology. Currently, many strategies are being tested that either inhibit, eradicate or prevent the development of plaques in AD. An exciting new approach on the horizon is the immunization approach. Dramatic results from AD animal models have shown promise for active and passive immune therapies targeting A β. However, there is very limited data in humans that suggests a clear benefit. Some hurdles faced with these studies arise from complications noted with therapy. Encephalitis has been reported in trials of active immunization and vasogenic edema or amyloid - related imaging abnormalities (ARIA) has been reported with passive immunization in a minority of patients. As yet, therapies targeting only tau are still limited to mouse models with few studies targeting both pathologies. As the majority of approaches tried so far are based on targeting a self - protein, though in an abnormal conformation, benefits of therapy need to be balanced against the possible risks of stimulating excessive toxic inflammation. For better efficacy, future strategies will need to focus on the toxic oligomers and targeting all aspects of AD pathology.

GDE2 promotes neurogenesis by glycosylphosphatidylinositol-anchor cleavage of RECK

The six-transmembrane protein glycerophosphodiester phosphodiesterase 2 (GDE2) induces spinal motor neuron differentiation by inhibiting Notch signaling in adjacent motor neuron progenitors. GDE2 function requires activity of its extracellular domain that shares homology with glycerophosphodiester phosphodiesterases (GDPDs). GDPDs metabolize glycerophosphodiesters into glycerol-3-phosphate and corresponding alcohols, but whether GDE2 inhibits Notch signaling by this mechanism is unclear. Here, we show that GDE2, unlike classical GDPDs, cleaves glycosylphosphatidylinositol (GPI) anchors. GDE2 GDPD activity inactivates the Notch activator RECK (reversion-inducing cysteine-rich protein with kazal motifs) by releasing it from the membrane through GPI-anchor cleavage. RECK release disinhibits ADAM (a disintegrin and metalloproteinase) protease-dependent shedding of the Notch ligand Delta-like 1 (Dll1), leading to Notch inactivation. This study identifies a previously unrecognized mechanism to initiate neurogenesis that involves GDE2-mediated surface cleavage of GPI-anchored targets to inhibit Dll1-Notch signaling.

GDE2 regulates subtype-specific motor neuron generation through inhibition of Notch signaling

The specification of spinal interneuron and motor neuron identities initiates within progenitor cells, while motor neuron subtype diversification is regulated by hierarchical transcriptional programs implemented postmitotically. Here we find that mice lacking GDE2, a six-transmembrane protein that triggers motor neuron generation, exhibit selective losses of distinct motor neuron subtypes, specifically in defined subsets of limb-innervating motor pools that correlate with the loss of force-generating alpha motor neurons. Mechanistically, GDE2 is expressed by postmitotic motor neurons but utilizes extracellular glycerophosphodiester phosphodiesterase activity to induce motor neuron generation by inhibiting Notch signaling in neighboring motor neuron progenitors. Thus, neuronal GDE2 controls motor neuron subtype diversity through a non-cell-autonomous feedback mechanism that directly regulates progenitor cell differentiation, implying that subtype specification initiates within motor neuron progenitor populations prior to their differentiation into postmitotic motor neurons.

Mitotic Waves in Laticifers of Euphorbia marginata

A successive pattern of nuclear divisions that result in mitotic waves has been observed within the coenocytic nonarticulated laticifers of embryos of Euphorbia marginata Pursh. These waves originate independently in the cotyledonary or hypocotyl portion of the laticifer and exhibit uni-or bidirectional movement at variable velocities. Individual nuclei or groups of neighoring nuclei in a laticifer were observed in a sequence of mitotic stages ranging from prophase to telophase; division activity varied with individual laticifers in an embryo. Two mitotic patterns were apparent in the embryo: a random pattern associated with various cells in the meristematic area, and a successive pattern restricted to the laticifer. A substance, synthesized by and restricted to the laticifer, may be associated with this mitotic pattern.

The antioxidant enzyme Prdx1 controls neuronal differentiation by thiol-redox-dependent activation of GDE2

The six-transmembrane protein GDE2 controls the onset and progression of spinal motor neuron differentiation through extracellular glycerophosphodiester phosphodiesterase metabolism. Although this process is likely to be tightly regulated, the relevant mechanisms that modulate its activity are unknown. Here we show that the antioxidant scavenger peroxiredoxin1 (Prdx1) interacts with GDE2, and that loss of Prdx1 causes motor neuron deficits analogous to GDE2 ablation. Prdx1 cooperates with GDE2 to drive motor neuron differentiation, and this synergy requires Prdx1 thiol-dependent catalysis. Prdx1 activates GDE2 through reduction of an intramolecular disulfide bond that bridges its intracellular N- and C-terminal domains. GDE2 variants incapable of disulfide bond formation acquire independence from Prdx1 and are potent inducers of motor neuron differentiation. These findings define Prdx1 as a pivotal regulator of GDE2 activity and suggest roles for coupled thiol-redox-dependent cascades in controlling neuronal differentiation in the spinal cord.

Dynamic role of kallikrein 6 in traumatic spinal cord injury

Kallikrein 6 (K6) is a member of the kallikrein gene family that comprises 15 structurally and functionally related serine proteases. In prior studies we showed that, while this trypsin-like enzyme is preferentially expressed in neurons and oligodendroglia of the adult central nervous system (CNS), it is up-regulated at sites of injury due to expression by infiltrating immune and resident CNS cells. Given this background we hypothesized that K6 is a key contributor to the pathophysiology of traumatic spinal cord injury (SCI), influencing neural repair and regeneration. Examination of K6 expression following contusion injury to the adult rat cord, and in cases of human traumatic SCI, indicated significant elevations at acute and chronic time points, not only at the injury site but also in cord segments above and below. Elevations in K6 were particularly prominent in macrophages, microglia and reactive astrocytes. To determine potential effects of elevated K6 on the regeneration environment, the ability of neurons to adhere to and extend processes on substrata which had been exposed to recombinant K6 was examined. Limited (1 h) or excess (24 h) K6-mediated proteolytic digestion of a growth-facilitatory substrate, laminin, significantly decreased neurite outgrowth. By contrast, similar hydrolysis of a growth-inhibitory substrate, aggrecan, significantly increased neurite extension and cell adherence. These data support the hypothesis that K6 enzymatic cascades mediate events secondary to spinal cord trauma, including dynamic modification of the capacity for axon outgrowth.

Autogenous common facial vein or external jugular vein patch for carotid endarterectomy

BACKGROUND

The purpose of this study was to determine whether common facial vein or external jugular vein are as good a vein patch as a saphenous vein for carotid patch angioplasty.

METHOD

Retrospectively, 19 patients who underwent everted common facial vein or external jugular vein patch were compared with 199 patients who underwent saphenous vein patch carotid endarterectomy during 1989 to 1996. The two groups were compared clinically and by sonographic surveillance. The mean follow-up was 18+/-4 months for common facial vein/external jugular vein patients and 48+/-15 months for saphenous vein patch group.

RESULTS

No significant differences in mortality or morbidity were observed among patients in whom everted common facial vein or external jugular vein was used as compared with saphenous vein. No bleeding, thrombotic event, dilation of the patch or aneurysmal degeneration and perioperative deaths occurred in either of the two groups. Duplex surveillance studies showed no significant difference in recurrent moderate (50-79%) and severe (80-99%) stenosis.

CONCLUSION

Everted common facial vein or external jugular vein patch was comparable to other vein patches. This eliminates the comorbidity of groin incision. Also, using everted common facial vein or external jugular vein as vein patch saves saphenous vein to be used for other vascular procedures, such as coronary artery or lower extremity bypass.

Adrenal Insufficiency—An Unusual Cause of Shock in Postoperative Patients

OBJECTIVE

To remind physicians that adrenal insufficiency can cause postoperative shock and that the manifestations are difficult to distinguish from those of sepsis.

METHODS

We present detailed case reports of three patients who had hyperdynamic shock in the surgical intensive-care unit and describe their response to the cosyntropin stimulation test.

RESULTS

All three patients were diagnosed as having adrenal insufficiency with use of the cosyntropin stimulation test. Two of the three patients rapidly recovered; however, because of delay in the diagnosis of adrenal insufficiency, the third patient succumbed to multisystem organ failure.

CONCLUSION

The cases presented highlight the need to exclude adrenal insufficiency as a possible cause of hyperdynamic circulatory shock, particularly when no clear-cut diagnosis exists. Early recognition of adrenal insufficiency is important and can result in reversal of shock and prevention of death. Adrenal insufficiency can be diagnosed through screening random cortisol levels and by use of the cosyntropin stimulation test. Patients in addisonian crisis often respond to the first dose of glucocorticoid with dramatic improvement in blood pressure and systemic vascular resistance. Administration of glucocorticoid can thus lead to improved organ perfusion and recovery of organ function. Delays in diagnosis and treatment of acute hypoadrenalism can have a fatal outcome.

Right atrial thrombus in a patient with stage IV carcinoma of the lung: is the surgical treatment the correct choice?

Thrombus in the right atrium or ventricle is rare and carries a mortality rate of 40%. Death frequently occurs when the thrombus moves toward the pulmonary arteries. Emergent treatment is therefore required. However there is no clear consensus regarding therapeutic management. We present here a patient with right atrial thrombus who underwent surgical exploration of the right atrium and successful thrombectomy.

Growth hormone synthesized and secreted by human thymocytes acts via insulin-like growth factor I as an autocrine and paracrine growth factor

There is increasing evidence that GH can influence immune function and that it is secreted by lymphocytes. In the present study we investigated the endogenous synthesis and secretion of GH and insulin-like growth factor I (IGF-I) from human thymocytes and evaluated the autocrine/paracrine effects of GH and IGF-I on T cell and thymic epithelial cell proliferation. First, the presence of thymic GH and IGF-I was detected by RIA of thymocyte extracts. Next, using a hormonal enzyme-linked immunoplaque assay, we found that thymocytes secreted GH and IGF-I. Further, we documented the endogenous synthesis of GH by human thymocytes using [35S]methionine labeling followed by immunoprecipitation, gel electrophoresis, and autoradiography. We then evaluated the physiological role of endogenously generated GH and IGF-I. Using an affinity-purified-GH polyclonal antibody, we observed a marked inhibition (P < 0.04) of phytohemagglutinin-stimulated thymocyte proliferation, suggesting an autocrine/paracrine role for the secreted GH. Further, we observed significant (P < 0.001) increases in thymocyte proliferation in cultures stimulated with varying doses of GH and IGF-I. Also, conditioned medium of human thymocytes (1 x 10(5) cells) stimulated with GH for 48 h contained a significant (P < 0.001) amount of IGF-I. Thymocyte proliferation stimulated by GH was significantly (P < 0.01) inhibited by monoclonal as well as polyclonal human IGF-I antisera. Finally, we studied the paracrine effect of thymocyte-secreted GH on human primary thymic epithelial cell (TEC) cultures. A significant (P < 0.05) increase in [3H]thymidine uptake in TEC cultures after GH addition was observed, which was abolished by GH antiserum. Polyclonal and monoclonal IGF-I antisera significantly (P < 0.05) inhibited GH-stimulated TEC proliferation. In summary, human thymocytes synthesize and secrete GH and IGF-I. Further, GH functions as an autocrine/paracrine growth factor in the human thymus via locally synthesized IGF-I.

Delayed diagnosis of psychological erectile dysfunction because of the presence of macroprolactinemia

Idiopathic hyperprolactinemia can be found in men with either normal or low serum testosterone (T) levels. The explanation for the differing effects on T of similar PRL levels has not been found. Macroprolactinemia, as a clinical entity, has been reported mostly in women. These macromolecules are biologically less active and/or are transported less easily across the capillary bed than the 22-kDa molecules. Therefore, women with elevated PRL levels retain normal menses and fertility. We studied six men, aged 28-53 yr (mean, 45 yr), in whom hyperprolactinemia was initially considered to be the cause of their erectile dysfunction. PRL levels ranged from 25-92 ng/mL (normal, 2-15 ng/mL), but T and gonadotropin levels were normal, suggesting that PRL was not disrupting gonadotropin and gonadal steroid function. The results of magnetic resonance imaging studies of the pituitary gland were normal. Separation by Sephadex G-100 column chromatography showed a predominance (85-90%) of big (60 kDa) and big big ( > 150 kDa) PRL, in contrast to the predominance of 22-kDa PRL in normal subjects. Nocturnal tumescence testing was normal, supporting the diagnosis of psychogenic impotence in these subjects, and potency returned after counseling. Hence, the biologically inactive macroprolactinemia did not cause any organic derangement in erectile function. It further obscured and delayed the appropriate diagnosis and treatment of these individuals.

Growth hormone secretion by human peripheral blood mononuclear cells detected by an enzyme-linked immunoplaque assay

In order to evaluate the secretion of GH from human peripheral blood mononuclear cells (PBMC) and its possible role as a modulator of lymphoproliferation, we have developed a hormonal enzyme-linked immunoplaque assay. This assay captures GH between a monoclonal and polyclonal antibody. This is followed by adding substrate and a horseradish peroxidase-conjugated antibody against the polyclonal antibody which produces violet colored plaques where GH has been secreted. This assay is sensitive, specific, highly reproducible, and can detect picogram quantities of GH. Using this assay we have detected GH secretion from approximately 1% of human PBMC under unstimulated conditions. Regression analysis showed a linear relationship between the number of cells plated and the number of GH plaques formed. Therefore, GH plaques were formed by single cells or its progeny and did not represent aggregation of secreting cells. Preincubation of PBMC with cycloheximide, a protein synthesis inhibitor, completely abolished the formation of GH plaques which suggests that the PBMC were responsible for the synthesis of the secreted GH. In addition, we have also observed that stimulation of human PBMC with T-cell mitogens, Concanavalin A and PHA and the cytokine IL-2 led to significant increases in GH plaque area and number whereas stimulation with LPS, a B cell mitogen, was ineffective. The PHA and IL-2 induced increase in plaque number suggests that they can recruit noncommitted lymphocytes to actively secrete GH which raises the possibility that this secreted GH may serve as a growth factor in T cell proliferation. We conclude that this immunoplaque assay may be useful in evaluating the secretion of other peptides from human immune cells.

Human thymocytes secrete luteinizing hormone: an autocrine regulator of T-cell proliferation

There is evidence that there may be bidirectional communication between immune and gonadotropin producing cells. In the present study we describe the secretion and function of an LH like peptide secreted from the human thymus. Serial dilutions of thymic extracts obtained from surgically removed thymic tissues displaced I125 LH from LH antiserum parallel to that produced by pituitary LH. Thymic LH was detected as early as 10 days of age and maximal concentrations were noted at 5 months. Utilizing a sensitive and specific hormonal enzyme linked immunoplaque assay developed in our laboratory, we were able to detect LH secretion from unstimulated human thymocytes. Neutralizing endogenously released LH in PHA stimulated thymocytes with LH antiserum significantly inhibited thymidine incorporation. We conclude that an LH-like peptide is secreted by human thymocytes which acts as an autocrine co-mitogen in lymphoproliferation.

Prolactin synthesized and secreted by human peripheral blood mononuclear cells: an autocrine growth factor for lymphoproliferation

Prolactin has been shown to have an immunoregulatory role in the rodent immune response. A prolactin-like molecule has also been found in mouse splenocytes and a human B-lymphoblastoid cell line. We have evaluated whether human peripheral blood mononuclear cells (PBMCs) synthesize and/or secrete prolactin. We used the polymerase chain reaction (PCR) to generate a 276-base-pair prolactin product from human PBMCs, and Southern blot analysis confirmed that it was related to prolactin. Western blotting using a polyclonal antibody to prolactin indicated that cell extracts prepared from human PBMCs contained a high molecular mass (60-kDa) immunoreactive prolactin. To determine whether this PBMC prolactin was being secreted, we developed a highly sensitive and specific hormonal enzyme-linked immunoplaque assay. With this assay, we were able to detect human prolactin secretion from concanavalin A (Con A)- or phytohemagglutinin-stimulated PBMCs but not from unstimulated PBMCs. We next sought to determine whether this secreted prolactin could function as an autocrine growth factor in lymphoproliferation. We observed that anti-human prolactin antiserum significantly inhibited human PBMC proliferation in response to Con A or phytohemagglutinin. We conclude that a prolactin-like molecule is synthesized and secreted by human PBMCs and that it functions in an autocrine manner as a growth factor for lymphoproliferation.