Arterioureteral fistula--a rare complication of ureterolithotomy: treatment with embolization

Fistula formation between a ureteral branch of a renal artery and the ipsilateral ureter is rare. We describe a case that followed ureterolithotomy of an impacted stone. Selective angiography with embolization of the bleeding branch was curative.     

Dexamethasone incorporating liposomes: an in vitro study of their applicability as a slow releasing delivery system of dexamethasone from covered metallic stents

Aim: To investigate the possibility of covering PET-covered commercially available metallic stents, with liposomal dexamethasone that will act as a slow releasing drug-depot at the site of interest. Methods: Large multilamellar (MLV), sonicated (SUV) and dried reconstituted (DRV) liposomes entrapping dexamethasone were prepared by thin film hydration, sonication and the DRV method, respectively, and applied on stents using a simple evaporation technique. Drug encapsulation and retention in liposomes were measured by HPLC. The presence of liposomes on the stent surface was confirmed by scanning electron microscopy, while the release of dexamethasone and lipid from the liposome-covered stent was evaluated under different conditions (flow rate, presence of plasma proteins), in an in vitro assembly that was developed to simulate in vivo conditions. Results: The release of dexamethasone from liposome-covered stents ranged from 25% to 50% after 48 h of incubation in buffer, depending on the type of liposome. The release was highest from stents covered with DRV liposomes. When increasing the flow rate from 2 to 6 ml/min a slight increase in release of drug was observed, while a higher release was measured when stents were incubated in plasma proteins. Liposome size does not affect liposome placement on stents. Conclusion: The basic characteristics that should be considered when preparing liposomes to cover stents should be their drug loading capacity and their stability under the conditions prevailing at the site of interest. By preparing the appropriate formulation, it is possible that liposomal drugs may be used to cover stents and serve as drug releasing depots at the site of interest. Further in vitro and in vivo studies are needed in order to exploit the possible applications of this methodology.     

Overexpression of the replication licensing regulators hCdt1 and hCdc6 characterizes a subset of non-small-cell lung carcinomas: synergistic effect with mutant p53 on tumor growth and chromosomal instability--evidence of E2F-1 transcriptional control over hCdt1

Replication licensing ensures once per cell cycle replication and is essential for genome stability. Overexpression of two key licensing factors, Cdc6 and Cdt1, leads to overreplication and chromosomal instability (CIN) in lower eukaryotes and recently in human cell lines. In this report, we analyzed hCdt1, hCdc6, and hGeminin, the hCdt1 inhibitor expression, in a series of non-small-cell lung carcinomas, and investigated for putative relations with G(1)/S phase regulators, tumor kinetics, and ploidy. This is the first study of these fundamental licensing elements in primary human lung carcinomas. We herein demonstrate elevated levels (more than fourfold) of hCdt1 and hCdc6 in 43% and 50% of neoplasms, respectively, whereas aberrant expression of hGeminin was observed in 49% of cases (underexpression, 12%; overexpression, 37%). hCdt1 expression positively correlated with hCdc6 and E2F-1 levels (P = 0.001 and P = 0.048, respectively). Supportive of the observed link between E2F-1 and hCdt1, we provide evidence that E2F-1 up-regulates the hCdt1 promoter in cultured mammalian cells. Interestingly, hGeminin overexpression was statistically related to increased hCdt1 levels (P = 0.025). Regarding the kinetic and ploidy status of hCdt1- and/or hCdc6-overexpressing tumors, p53-mutant cases exhibited significantly increased tumor growth values (Growth Index; GI) and aneuploidy/CIN compared to those bearing intact p53 (P = 0.008 for GI, P = 0.001 for CIN). The significance of these results was underscored by the fact that the latter parameters were independent of p53 within the hCdt1-hCdc6 normally expressing cases. Cumulatively, the above suggest a synergistic effect between hCdt1-hCdc6 overexpression and mutant-p53 over tumor growth and CIN in non-small-cell lung carcinomas.     

Cdt1 overexpression drives colorectal carcinogenesis through origin overlicensing and DNA damage

Chromatin licensing and DNA replication factor 1 (CDT1), a protein of the pre-replicative complex, is essential for loading the minichromosome maintenance complex (MCM) helicases onto the origins of DNA replication. While several studies have shown that dysregulation of CDT1 expression causes re-replication and DNA damage in cell lines, and CDT1 is highly expressed in several human cancers, whether CDT1 deregulation is sufficient to enhance tumorigenesis in vivo is currently unclear. To delineate its role in vivo, we overexpressed Cdt1 in the mouse colon and induced carcinogenesis using azoxymethane/dextran sodium sulfate (AOM/DSS). Here, we show that mice overexpressing Cdt1 develop a significantly higher number of tumors with increased tumor size, and more severe dysplastic changes (high-grade dysplasia), compared with control mice under the same treatment. These tumors exhibited an increased growth rate, while cells overexpressing Cdt1 loaded greater amounts of Mcm2 onto chromatin, demonstrating origin overlicensing. Adenomas overexpressing Cdt1 showed activation of the DNA damage response (DDR), apoptosis, formation of micronuclei, and chromosome segregation errors, indicating that aberrant expression of Cdt1 results in increased genomic and chromosomal instability in vivo, favoring cancer development. In line with these results, high-level expression of CDT1 in human colorectal cancer tissue specimens and colorectal cancer cell lines correlated significantly with increased origin licensing, activation of the DDR, and microsatellite instability (MSI). © 2022 The Pathological Society of Great Britain and Ireland.     

Glial modulation of synaptic transmission: Insights from the supraoptic nucleus of the hypothalamus

Astrocytes clear synaptically released glutamate from the extracellular space through high-affinity transporters present on their plasma membrane. By controlling the extracellular level of the main excitatory transmitter in the central nervous system, astrocytes thus contribute prominently to the regulation of overall cellular excitability and synaptic information processing. We recently investigated the influence of the glial environment on glutamatergic and GABAergic neurotransmission in the supraoptic nucleus of the rat hypothalamus under physiological conditions such as lactation that significantly reduce astrocytic coverage of its neurons. By performing electrophysiological analyses on this unique model of dynamic neuronal-glial interactions, we have been able to show that the fine astrocytic processes normally enwrapping synapses serve two important functions. First, they govern the level of activation of presynaptic metabotropic glutamate receptors on glutamatergic terminals, thereby regulating synaptic efficacy at excitatory synapses. Second, they act as a physical and functional barrier to diffusion in the extracellular space, limiting spillover of glutamate and other neuroactive substances and therefore contributing to the regulation of heterosynaptic transmission and intercellular communication.     

GABAA receptor-expressing astrocytes in the supraoptic nucleus lack glutamate uptake and receptor currents

An important function of astrocytes is the clearance of excess extracellular glutamate via specific carriers whose expression has become an astrocytic marker. In the present study, we found that a large population of astrocytes in the supraoptic nucleus (SON) of the rat hypothalamus lacks glutamate uptake currents and receptor responses but expresses GABAA receptors. Patch clamp recordings in acute hypothalamic slices that included the SON showed typical astrocytic membrane currents and demonstrated that GABA, via GABAA receptor activation, triggered a conductance increase with the reversal potential close to the Cl- equilibrium potential and a decrease in resting K+ conductance. Intracellular labeling with Lucifer Yellow revealed that these cells had a radial glia-like morphology, with cell bodies lined up along the base of the brain and long processes traversing the nucleus; they were not dye-coupled. Parallel immunocytochemical labelings showed that they expressed strong GABAA receptor and glial fibrillary acidic protein (GFAP) immunoreactivities. In addition, our electrophysiological and morphological analyses revealed another population of astrocytes in this nucleus, located next to the subarachnoid space. They were less numerous than the radial type, had a round morphology and few processes, and were dye-coupled. Unlike the radial astrocytes, they showed little immunoreactivity for GABAA receptor or GFAP. Moreover, they did not respond to GABA but to glutamate, a response that was partially mimicked by aspartate, indicating glutamate transporter expression. Taken together, our observations add to growing evidence illustrating heterogeneity of astrocytes in the adult brain, a heterogeneity that reflects striking differences in form and function of astrocytic populations in regions as discrete as the SON of the hypothalamus.     

Glutamatergic input governs periodicity and synchronization of bursting activity in oxytocin neurons in hypothalamic organotypic cultures

During suckling, oxytocin (OT) neurons display a bursting electrical activity, consisting of a brief burst of action potentials which is synchronized throughout the OT neuron population and which periodically occurs just before each milk ejection in the lactating rat. To investigate the basis of such synchronization, we performed simultaneous intracellular recordings from pairs of OT neurons identified retrospectively by intracellular fluorescent labelling and immunocytochemistry in organotypic slice cultures derived from postnatal rat hypothalamus. A spontaneous bursting activity was recorded in 65% of OT neurons; the remaining showed only a slow, irregular activity. Application of OT triggered bursts in nonbursting neurons and accelerated bursting activity in spontaneously bursting cells. These cultures included rare vasopressinergic neurons showing no bursting activity and no reaction to OT. Bursts occurred simultaneously in all pairs of bursting OT neurons but, as in vivo, there were differences in burst onset, amplitude and duration. Coordination of firing was not due to electrotonic coupling because depolarizing one neuron in a pair had no effect on the membrane potential of its partner and halothane and proprionate did not desynchronize activity. On the other hand, bursting activity was superimposed on volleys of excitatory postsynaptic potentials (EPSPs) which occurred simultaneously in pairs of neurons. EPSPs, and consequently action potentials, were reversibly blocked by the non-NMDA glutamatergic receptor antagonist CNQX. Taken together, these data, obtained from organotypic cultures, strongly suggest that a local hypothalamic network governs synchronization of bursting firing in OT neurons through synchronous afferent volleys of EPSPs originating from intrahypothalamic glutamatergic inputs.     

Humoral immune reactivity against human leukocyte antigen (HLA)-DQ graft molecules in the early posttransplantation period

Humoral graft-specific alloreactivity was investigated in 110 renal transplant (RTx) recipients (group A) starting immediately postTx and in 32 RTx candidates sensitized against a failed graft (group B) using an enzyme-linked immunosorbent assay (ELISA) assay. All patients received a human leukocyte antigen (HLA) class I and II incompatible graft. Donor-specific (DS) antibodies were detected in 11 of 110 (90.9%) group-A patients, predominately during the first 6 months postTx. In all 11 cases, only HLA class II antibodies were detected. Ten of 11 antibody-positive patients received an HLA-DR, HLA-DQ incompatible graft, and all patients had HLA-DQ DS antibodies, either alone (n=8) or with HLA-DR antibodies (n=2). HLA-DQ antibodies were also detected in 80.9% of group-B patients. The presence of HLA-DQ DS antibodies in the early postTx period does not identify patients with rejection or deterioration of graft function. Whether these patients are at high risk for graft loss remains to be clarified.     

Correlation of MDR-1, nm23-H1 and H Sema E gene expression with histopathological findings and clinical outcome in ovarian and breast cancer patients

The development of a molecular screening method for cancer patients is of great importance, since it would contribute to the selection of the most effective chemotherapy regimen for each patient. In the present study we applied such a method, semi-quantative RT-PCR analysis, and we examined the expression of the multidrug resistance gene MDR-1, the metastasis suppressor gene nm23-H1 and the non-MDR drug resistant gene H Sema E in 53 ovarian and breast cancer specimens. Moreover, we have correlated the expression profile of these genes with the histopathological findings and clinical outcome of the examined patients. The majority of specimens were found to be positive for MDR-1 and H Sema E gene expression, while nm23-H1 was detected in less than 50% of the patients. Correlation and statistical analysis of the molecular data with clinicopathological features showed that nm23-H1 could serve as a good prognostic factor for ovarian cancer patients. In breast cancer patients, nm23-H1 expression was associated with a 6.1 higher death risk. Ovarian cancer patients who express nm23-H1, but not MDR-1 and H Sema E, tend to have longer survival than patients with any other gene combination. Finally, breast cancer patients with advanced disease showed a better response when they were negative for all the three genes studied. In conclusion this work proposes that the combined study of the expression of different genes may be a useful approach for evaluating patients' response to therapy.     

Changes of gastric emptying rate and gastrin levels are early indicators of autonomic neuropathy in type II diabetic patients

The authors investigated the effect of a balanced meal on gastric emptying rate and gastrin plasma concentrations in patients with type II diabetes and autonomic neuropathy, in diabetic patients without autonomic neuropathy, and in healthy subjects (controls). Before food the gastrin plasma concentrations were higher in patients with diabetes with autonomic neuropathy. After food, gastric emptying rate was slower in patients with diabetes with autonomic neuropathy, whereas gastrin plasma concentrations increased in 30 minutes in all groups but to a greater extent in patients with diabetes with autonomic neuropathy. Sixty minutes after food, there was a significant decrease in gastrin plasma concentrations in patients with diabetes with autonomic neuropathy, compared with the other two groups. These data suggest that in patients with type II diabetes with autonomic neuropathy, food causes slower gastric emptying and different plasma gastrin level responses from those in patients with type II diabetes without autonomic neuropathy and controls. There are therefore differences in the responses to food ingestion between these groups because of vagal denervation induced by autonomic neuropathy. These tests should be reserved for patients with symptoms suggestive of disturbed gastric emptying, or for patients with autonomic neuropathy without symptoms of gastroparesis.