The lateral entorhinal cortex is a hub for local and global dysfunction in early Alzheimer’s disease states

Functional network activity alterations are one of the earliest hallmarks of Alzheimer’s disease (AD), detected prior to amyloidosis and tauopathy. Better understanding the neuronal underpinnings of such network alterations could offer mechanistic insight into AD progression. Here, we examined a mouse model (3xTgAD mice) recapitulating this early AD stage. We found resting functional connectivity loss within ventral networks, including the entorhinal cortex, aligning with the spatial distribution of tauopathy reported in humans. Unexpectedly, in contrast to decreased connectivity at rest, 3xTgAD mice show enhanced fMRI signal within several projection areas following optogenetic activation of the entorhinal cortex. We corroborate this finding by demonstrating neuronal facilitation within ventral networks and synaptic hyperexcitability in projection targets. 3xTgAD mice, thus, reveal a dichotomic hypo-connected:resting versus hyper-responsive:active phenotype. This strong homotopy between the areas affected supports the translatability of this pathophysiological model to tau-related, early-AD deficits in humans.     

Human platelet-derived mitogens. II. Subcellular localization of insulinlike growth factor I to the alpha-granule and release in response to thrombin

Platelets contain mitogenic activities for MCF-7 human breast cancer cells when assayed under serum-free chemically defined conditions. Purification from outdated human platelets identified insulinlike growth factor I (IGF-I) as the most potent breast cancer cell mitogen in lysates (Karey KP, Sirbasku DA: see accompanying article, this issue). In this study the release and subcellular localization of IGF-I was investigated. Degranulation of platelets by thrombin treatment caused release of lysosomal enzymes (beta-glucuronidase and N-acetyl-D- glucosaminidase), alpha-granule proteins (beta-thromboglobulin and fibrinogen) as well as mitogenic activity for MCF-7 cells and IGF-I as measured by radioimmunoassay (RIA) and radioreceptor assay. Release of mitogenic activity and immunologically identified IGF-I was induced tenfold over controls by thrombin and was nearly complete as compared to platelets disrupted by repeated freezing and thawing. Disruption of platelets by nitrogen cavitation followed by separation of the organelles by sucrose density gradient sedimentation showed that IGF-I and mitogenic activity localized predominantly to fractions containing alpha-granules rather than soluble cellular components, lysosomes, or dense granules. The morphology of MCF-7 cells in serum-free medium supplemented with supernatants from thrombin-treated platelets also indicated the release of important cell-adhesion factors for human breast cancer cells.     

International guidelines for the management of pancreatic intraductal papillary mucinous neoplasms

The management of intraductal papillary mucinous neoplasms(IPMN) is presently evolving as a result of the improved understanding of the natural history and biological behavior of the different pancreatic cystic neoplasms; and better preoperative diagnosis of these neoplasms due to advancement in preoperative diagnostic tools. International consensus guidelines for the management of IPMN were first formulated in 2006 and subsequently revised in 2012. Both these guidelines were constructed based on expert opinion and not on robust clinical data. The main limitation of the original Sendai guidelines was that it had a low positive predictive value resulting in many benign neoplasms being resected. Hence,these guidelines were revised in 2012. However,although the updated guidelines resulted in an improvement in the positive predictive value over the Sendai Guidelines,the results of several studies validating these guidelines demonstrated that its positive predictive value remained low. Furthermore,although both guidelines were associated with high negative predictive values,several investigators have demonstrated that some malignant IPMNs may be missed. Finally,it is imperative to emphasize that major considerations when managing a patient with IPMN including the patient's surgical risk,life-expectancy and even cost of investigations are not taken into account in current guidelines. The management of a patient with IPMN should be individualized and tailored according to a patient's risk benefit profile for resection vs surveillance.     

Long-term antigen challenge results in progressively diminished mucosal mast cell degranulation in rats

BACKGROUND & AIMS: The effects of short-term antigenic activation of mast cells on the gastrointestinal tract have been well characterized, but little is known about the effects of long-term exposure to antigen on mucosal mast cell reactivity. The aim of this study was to determine the effects of long-term antigen exposure on mucosal mast cell reactivity in the gastrointestinal mucosa. METHODS: Rats sensitized to chicken ovalbumin were orally challenged (short-term or long-term) with antigen. Rat mast cell protease II (RMCP-II) content was measured in serum as an index of mucosal mast cell degranulation. RESULTS: Short- term oral antigen challenge caused a 30-fold increase in serum RMCP-II levels. RMCP-II release was markedly diminished in long term-challenged rats (P < 0.001), despite increased tissue RMCP-II levels in stomach and jejunum. Although short-term antigen challenge significantly increased gastric acid secretion, no such response was observed after the long-term antigen challenge. In rats undergoing long-term challenge, a significant release of RMCP-II in response to intravenous antigen was not observed; however, mucosal mast cells remained responsive to intravenous anti-immunoglobulin E. CONCLUSIONS: Repeated activation of mucosal mast cells results in a progressive diminution of RMCP-II release not attributable to depletion of this mediator. This may represent an adaptive response aimed at minimizing the potentially deleterious effects of repeated exposure to an antigen. (Gastroenterology 1996 Dec;111(6):1516-23)     

Leukemia inhibitory factor upregulates cytokine expression by a murine stromal cell line enabling the maintenance of highly enriched competitive repopulating stem cells

Attempts to maintain or expand primitive hematopoietic stem cells in vitro without the concomitant loss of their differentiative and proliferative potential in vivo have largely been unsuccessful. To investigate this problem, we compared the ability of three cloned bone marrow (BM) stromal cell lines to support the growth of primitive Thy- 1lo Sca-1+H-2Khi cells isolated by fluorescence-activated cell sorting from the BM of Ly-5.2 mice treated 1 day previously with 5-fluo- rouracil. Sorted cells were highly enriched in cobblestone area-forming cells (CAFC), but their frequency was dependent on the stromal cell lines used in this assay (1 per 45 cells on SyS-1; 1 per 97 cells on PA6). In the presence of recombinant leukemia inhibitory factor (LIF), CAFC cloning efficiency was increased to 1 per 8 cells on SyS-1 and 1 per 11 cells on PA6, thus showing the high clonogenicity of this primitive stem cell population. More primitive stem cells with competitive repopulating potential were measured by injecting the sorted cells into lethally irradiated Ly-5.1 mice together with 10(5) radioprotective Ly-5.1 BM cells whose long-term repopulating ability has been "compromised" by two previous cycles of marrow transplantation and regeneration. Donor-derived lymphocytes and granulocytes were detected in 66% of animals injected with 50 sorted cells. To quantitate the maintenance of competitive repopulating units (CRU) by stromal cells, sorted cells were transplanted at limiting dilution before and after being cultured for 2 weeks on adherent layers of SyS-1, PA6, or S17 cells. CRU represented 1 per 55 freshly sorted cells. CRU could be recovered from cocultures supported by all three stromal cell lines, but their numbers were approximately-sevenfold less than on day 0. In contrast, the addition of LIF to stromal cultures improved CRU survival by 2.5-fold on S17 and PA6 cells (approximately two-fold to threefold decline), and enabled their maintenance on SyS-1. LIF appeared to act indirectly, because alone it did not support the proliferation of Thy- 1lo Sca-1+H-2Khi cells in stroma-free cultures. Polymerase chain reaction (RT-PCR) analysis revealed that Interleukin-1beta (IL-1 beta) IL-2, IL-6, granulocyte-colony stimulating factor, granulocyte macrophage-colony stimulating factor, transforming growth factors, LIF, and Steel Factor (SLF) mRNAs were upregulated in SyS-1 within 1 to 6 hours of LIF-stimulation. To determine if increased expression of SLF by LIF-stimulated SyS-1 cells could account for their capacity to support stem cells, sorted calls were cocultured on simian CV-E cells that were transfected with an expression vector encoding membrane-bound SLF, or supplemented with soluble SLF. In both cases, SLF synergized with IL-6 produced endogenously by CV-E cells enabling CAFC growth equivalent to that on LIF-stimulated SyS-1. CAFC development on LIF- stimulated SyS-1 could also be completely abrogated by an anti-SLF antibody. These data provide evidence for a role of LIF in the support of long-term repopulating stem cells by indirectly promoting cytokine expression by BM stroma. Furthermore, we have used quantitative assays to show a maintenance of CRU numbers, with retention of in vivo function following ex vivo culture.     

Temporomandibular joint injuries

The clinical and radiologic findings in 30 patients who sustained injuries to the temporomandibular joint (TMJ) were retrospectively analyzed. Imaging consisted of variable combinations of radiography, tomography, two-compartment arthrography, computed tomography, and magnetic resonance imaging and was performed 2 days to 24 months after injury. Indications for imaging included acquired and/or unstable occlusal disturbances, cephalalgia, facial pain, otalgia, TMJ pain, tinnitus, dizziness, hearing disturbance, masticatory dysfunction, and muscle atrophy. Radiologic findings included internal derangement of the TMJ meniscus, swelling of retrodiskal tissues, joint effusion, mandibular condyle and condylar neck fractures, osteochondritis dissecans, avascular necrosis, degenerative condylar remodeling, osteoarthritis, musculotendinous injuries, and atrophy of masticatory muscles. After imaging studies, seven patients underwent surgery, at which time imaging findings were confirmed; one patient underwent successful aspiration of a painful hemarthrosis. TMJ injuries may result in joint derangement, radiologically demonstrable joint degeneration, masticatory muscle dysfunction, pain, and progressive clinical disability.     

In vivo and in vitro MR imaging of renal tumors: histopathologic correlation and pulse sequence optimization

Magnetic resonance (MR) imaging has given mixed results in the detection of renal masses. To identify the reasons for this and to determine the optimal pulse sequences for evaluating renal tumors, the authors imaged 12 primary renal tumors in vivo and 17 in vitro at 0.35 T. Histopathologic findings for each specimen were closely correlated with the MR images. Four of seven solid tumors imaged in vivo were isointense with surrounding normal renal parenchyma at all pulse sequences. The other three tumors were hyperintense in vivo at T2-weighted sequences. At heavily T2-weighted sequences eight solid tumors were hyperintense in vitro and four were hypointense. There was no correlation between signal intensity and specific tissue type or histologic pattern for solid tumors. The five cystic tumors were well seen both in vivo and in vitro on T2-weighted images. However, the signal intensity of the cyst fluid was an unreliable indicator of benignancy. SE MR imaging at 0.35 T has significant limitations in the detection of solid renal masses.     

von Willebrand Disease : A Clinico-haematological Spectrum

Background

Bleeding disorders are commonly seen in clinical practice. von Willebrand Disease (vWD), is the commonest and yet a profoundly under diagnosed cause, having a wide spectrum of clinical presentation. Of its three types, type 1 vWD (70% of the total vWD cases) has the mildest and a highly variable clinical and laboratory presentation.

Methods

A series of ten cases of vWD were comprehensively evaluated using recommended diagnostic parameters and therapeutic interventions.

Results

All major types of vWD were represented. A female preponderance, with primary presentation in the form of muco-cutaneous bleeds was observed. A positive history of consanguineous parental marriage and family history of bleeding disorder was elicited in two and three patients respectively. Nine patients were found to be anemic and thrombocytopenia was present in only one. Bleeding time by modified template (SIMPLATE) method, along with activated partial thromboplastin time (APTT) was increased in all ten cases and of these, nine had low factor VIII: C levels. Ristocetin induced platelet aggregation studies were abnormal in all the five cases it was performed. vWF:RCo activity determined in one individual was shown to be low. vWF:Ag assay was done in four cases revealing a near complete absence of von Willebrand factor antigen in one and mildly decreased levels in the other three. vWF multimer assay was advised in three cases. DDAVP, plasma derived vWF, blood products and local antifibrinolytics were used as primary modalities of treatment

Conclusion

Thus, strong clinical suspicion, thorough clinical evaluation and judicious use of investigations including repeated investigations at different times are needed for making a diagnosis of vWD.Key Words: Bleeding disorders, von Willebrand Disease