Dendritic spikes in apical dendrites of neocortical layer 2/3 pyramidal neurons

Layer 2/3 (L2/3) pyramidal neurons are the most abundant cells of the neocortex. Despite their key position in the cortical microcircuit, synaptic integration in dendrites of L2/3 neurons is far less understood than in L5 pyramidal cell dendrites, mainly because of the difficulties in obtaining electrical recordings from thin dendrites. Here we directly measured passive and active properties of the apical dendrites of L2/3 neurons in rat brain slices using dual dendritic-somatic patch-clamp recordings and calcium imaging. Unlike L5 cells, L2/3 dendrites displayed little sag in response to long current pulses, which suggests a low density of I(h) in the dendrites and soma. This was also consistent with a slight increase in input resistance with distance from the soma. Brief current injections into the apical dendrite evoked relatively short (half-width 2-4 ms) dendritic spikes that were isolated from the soma for near-threshold currents at sites beyond the middle of the apical dendrite. Regenerative dendritic potentials and large concomitant calcium transients were also elicited by trains of somatic action potentials (APs) above a critical frequency (130 Hz), which was slightly higher than in L5 neurons. Initiation of dendritic spikes was facilitated by backpropagating somatic APs and could cause an additional AP at the soma. As in L5 neurons, we found that distal dendritic calcium transients are sensitive to a long-lasting block by GABAergic inhibition. We conclude that L2/3 pyramidal neurons can generate dendritic spikes, sharing with L5 pyramidal neurons fundamental properties of dendritic excitability and control by inhibition.

Ethinylestradiol differentially interferes with IGF-I in liver and extrahepatic sites during development of male and female bony fish

Growth and sexual development are closely interlinked in fish; however, no reports exist on potential effects of estrogen on the GH/IGF-I-axis in developing fish. We investigate whether estrogen exposure during early development affects growth and the IGF-I system, both at the systemic and tissue level. Tilapia were fed from 10 to 40 days post fertilization (DPF) with 17alpha-ethinylestradiol (EE(2)). At 50, 75, 90, and 165 DPF, length, weight, sex ratio, serum IGF-I (RIA), pituitary GH mRNA and IGF-I, and estrogen receptor alpha (ERalpha) mRNA in liver, gonads, brain, and gills (real-time PCR) were determined and the results correlated to those of in situ hybridization for IGF-I. Developmental exposure to EE(2) had persistent effects on sex ratio and growth. Serum IGF-I, hepatic IGF-I mRNA, and the number of IGF-I mRNA-containing hepatocytes were significantly decreased at 75 DPF, while liver ERalpha mRNA was significantly induced. At 75 DPF, a transient decline of IGF-I mRNA and a largely reduced number of IGF-I mRNA-containing neurons were observed in the female brain. In both sexes, pituitary GH mRNA was significantly suppressed. A transient downregulation of IGF-I mRNA occurred in ovaries (75 DPF) and testes (90 DPF). In agreement, in situ hybridization revealed less IGF-I mRNA signals in granulosa and germ cells. Our results show for the first time that developmental estrogen treatment impairs GH/IGF-I expression in fish, and that the effects persist. These long-lasting effects both seem to be exerted indirectly via inhibition of pituitary GH and directly by suppression of local IGF-I in organ-specific cells.

Time course of blood oxygenation level-dependent signal response after theta burst transcranial magnetic stimulation of the frontal eye field

The aim of the current study was to examine the effect of theta burst repetitive transcranial magnetic stimulation (rTMS) on the blood oxygenation level-dependent (BOLD) activation during repeated functional magnetic resonance imaging (fMRI) measurements. Theta burst rTMS was applied over the right frontal eye field in seven healthy subjects. Subsequently, repeated fMRI measurements were performed during a saccade-fixation task (block design) 5, 20, 35, and 60 min after stimulation. We found that theta burst rTMS induced a strong and long-lasting decrease of the BOLD signal response of the stimulated frontal eye field at 20 and 35 min. Furthermore, less pronounced alterations of the BOLD signal response with different dynamics were found for remote oculomotor areas such as the left frontal eye field, the pre-supplementary eye field, the supplementary eye field, and both parietal eye fields. Recovery of the BOLD signal changes in the anterior remote areas started earlier than in the posterior remote areas. These results show that a) the major inhibitory impact of theta burst rTMS occurs directly in the stimulated area itself, and that b) a lower effect on remote, oculomotor areas can be induced.

[Drug therapy of type-II diabetes: tablets, insulin or a combination of these]

Optimal therapy of diabetes has to be based on the known pathophysiology of metabolic disturbances and should eventually alleviate reduced secretion of insulin as well as reduce the usually present resistance to insulin in order to normalize the average blood glucose levels. In less than 30% of patients with type-II diabetes, dietetic measures combined with increased physical activity alone, are sufficient for metabolic control, thus increasing the importance of pharmacologic treatment immensely. Biguanides are the therapeutic choice in patients with massive overweight, because they usually do not induce weight gain; however, specific contraindications (renal failure in particular) have to be taken into consideration. The effect of blood glucose lowering by biguanides is not due to increased secretion of insulin, thus neither hypoglycemias nor hyperinsulinism are induced or increased, respectively. Patients with normal or slightly increased body weight should profit best from sulfonylureas that stimulate insulin production. Combinations of sulfonylurea and biguanides or of insulin and oral antidiabetics or insulin alone have to be taken into account when monotherapy with oral antidiabetics is too inefficient; however, clear and generally accepted guidelines for correct indications of these therapeutic modalities are lacking. Particularly in long-lasting diabetes and for patients with distinct overweight an adequate therapeutic success is often not obtained with the currently available therapeutic means. Possibly, future developments will provide new therapeutic ways with drugs that increase insulin sensitivity or reduce gluconeogenesis.

Streptozotocin-induced diabetes mellitus in pigs

We induced, as a precondition for a pancreas transplant, insulin-dependent diabetes mellitus in 67 Yorkshire Landrace pigs by administering streptozotocin. A dosage of 150 mg/kg body weight gave rise to a long-lasting diabetes mellitus that persisted with time (follow-up period: 26 weeks). Consecutive measurements of serum glucose and plasma insulin, before and up to 30 hours after administering streptozotocin, revealed triphasic behavior: initial hyperglycemia (1st to 3rd hour), pronounced hypoglycemia (12th to 18th hour), then hyperglycemia (22nd hour on). IVGTTs done 1 to 7 days after administering streptozotocin revealed a reduction of the K-value (glucose disappearance rate) from 0.3 (day 2) to 0.07 (day 4). Immunohistochemical studies revealed a complete loss of all beta-cells, concomitantly with a relative increase in glucagon- and somatostatin-positive cells. We also observed a complete loss of pp (pancreatic polypeptide)-positive cells. Diabetes induced by streptozotocin at 150 mg/kg body weight is complete and permanent; our mortality rate was 0%. Given the high morbidity rate after pancreatectomy, streptozotocin should be the method of choice for inducing diabetes mellitus in pigs.

Pneumococcal meningitis induces apoptosis in recently postmitotic immature neurons in the dentate gyrus of neonatal rats

Bacterial meningitis is associated with high rates of morbidity and mortality, despite advances in antibiotic therapy. Meningitis caused by Streptococcus pneumoniae is associated with a particularly high incidence of neurological sequelae including deficits resulting from damage to the hippocampus. Previous studies have documented that in neonatal rats with experimental pneumococcal meningitis, cells in the subgranular layer of the dentate gyrus undergo apoptosis. The aim of the present study was to define in more detail the nature of the dying cells in the dentate gyrus. Using bromodeoxyuridine labeling at different times before infection combined with immunocytochemistry, we identified the vulnerable cells as those which underwent mitosis 6-10 days before infection. A majority of these cells are of neuronal lineage. Thus, immature neuronal cells several days after the last cell division are preferentially triggered into apoptosis during pneumococcal meningitis. The loss of these cells may contribute to the long-lasting impairment of hippocampal function identified in animal models and in humans after bacterial meningitis.

Influence of preoperative functional status on outcome after total hip arthroplasty

BACKGROUND: International registries with large, heterogeneous patient populations provide excellent research opportunities for studying factors that influence treatment outcomes after total hip arthroplasty. In the present study, we used a European multinational database to investigate whether there is an association between three functional variables (preoperative pain, mobility, and motion) and functional outcome. METHODS: We performed a retrospective cohort study on preoperative and follow-up clinical data that were prospectively entered into the International Documentation and Evaluation System European hip registry between 1967 and 2002. The inclusion criteria for this study were an age of more than twenty years, an underlying diagnosis of osteoarthritis, and a Charnley class-A functional designation at the time of surgery. A total of 12,925 patients (13,766 total hip arthroplasties) who met these criteria were entered into the analysis. Three functional variables (pain, mobility, and motion) that were assessed preoperatively were evaluated postoperatively at various follow-up examinations for a maximum of ten years. RESULTS: Six thousand four hundred and one patients could walk longer than ten minutes preoperatively; of these, 57.1% had a walking capacity of more than sixty minutes at the time of the most recent follow-up. In comparison, 6896 patients had a preoperative walking capacity of less than ten minutes and only 38.9% of these patients could walk more than sixty minutes at the time of the most recent follow-up. The difference was significant (p < 0.01). Similarly, 10,375 patients had a preoperative hip flexion range of >70 degrees ; of these, 74.7% had a flexion range of >90 degrees at the time of the most recent follow-up. In comparison, 2793 patients had a preoperative hip flexion range of <70 degrees and only 62.6% of these patients had a flexion range of >90 degrees at the time of the most recent follow-up. The difference was also significant (p < 0.01). Lasting, complete, or almost complete pain relief was achieved by >80% of the patients following total hip arthroplasty regardless of their preoperative categorization of pain. CONCLUSIONS: Patients with poor preoperative walking capacity and hip flexion are less likely to achieve an optimal outcome with regard to walking and motion. In contrast, there is no correlation between the preoperative pain level and pain alleviation, which is generally good and long-lasting after total hip arthroplasty.

Maternal modulation of natal dispersal in a passerine bird: An adaptive strategy to cope with parasitism?

The decision of how far to disperse from the natal territory has profound and long-lasting consequences for young animals, yet the optimal dispersal behavior often depends on environmental factors that are difficult or impossible to assess by inexperienced juveniles. Natural selection thus favors mechanisms that allow the adaptive and flexible adjustment of the offspring's dispersal behavior by their parents via either paternal or maternal effects. Here we show that different dispersal strategies maximize the reproductive success of young great tits (Parus major) originating from a parasite-infested or a parasite-free nest and demonstrate that differential transfer of maternal yolk androgens in response to parasitism can result in a modification of the offspring's dispersal behavior that appears adaptive. It demonstrates that prenatal maternal effects are an important yet so far neglected determinant of natal dispersal and highlights the potential importance of maternal effects in mediating coevolutionary processes in host-parasite systems.

A diagnostically challenging case of ureterovaginal fistula after laparoscopic hysterectomy

A complicated case of iatrogenic ureterovaginal fistula in a 56-year-old woman after laparoscopic-assisted vaginal hysterectomy, which persisted after several attempts of repair including ureterocystoneostomy, is presented. Accurate radiologic work-up enabled us to identify a refluxing ureteral stump, which was not ligated at the time of ureterocystoneostomy, as the origin of urinary leakage. Surgical principles that should be adhered to when managing such complex cases to obtain successful long-lasting outcome are described.

Reduction in rat phosphatidylethanolamine binding protein-1 (PEBP1) after chronic corticosterone treatment may be paralleled by cognitive impairment: a first study

Chronic stress is associated with hippocampal atrophy and cognitive dysfunction. This study investigates how long-lasting administration of corticosterone as a mimic of experimentally induced stress affects psychometric performance and the expression of the phosphatidylethanolamine binding protein (PEBP1) in the adult hippocampus of one-year-old male rats. Psychometric investigations were conducted in rats before and after corticosterone treatment using a holeboard test system. Rats were randomly attributed to 2 groups (n = 7) for daily subcutaneous injection of either 26.8 mg/kg body weight corticosterone or sesame oil (vehicle control). Treatment was continued for 60 days, followed by cognitive retesting in the holeboard system. For protein analysis, the hippocampal proteome was separated by 2D electrophoresis (2DE) followed by image processing, statistical analysis, protein identification via peptide mass fingerprinting and gel matching and subsequent functional network mapping and molecular pathway analysis. Differential expression of PEBP1 was additionally quantified by Western blot analysis. Results show that chronic corticosterone significantly decreased rat hippocampal PEBP1 expression and induced a working and reference memory dysfunction. From this, we derive the preliminary hypothesis that PEBP1 may be a novel molecular mediator influencing cognitive integrity during chronic corticosterone exposure in rat hippocampus.

[Pregnancy in active acromegaly]

A 29-year-old woman with a long-lasting history of oligoamenorrhea, fell pregnant shortly after being diagnosed with acromegaly. LABORATORY TESTS AND IMAGING: A high IGF-1 concentration and an oral glucose tolerance test confirmed the diagnosis. Cranial magnetic resonance imaging demonstrated a macroadenoma of the pituitary with suprasellar extension and compression of the optic chiasm leading to incomplete hemianopsia.

Silencing of microRNAs in vivo with 'antagomirs'

MicroRNAs (miRNAs) are an abundant class of non-coding RNAs that are believed to be important in many biological processes through regulation of gene expression. The precise molecular function of miRNAs in mammals is largely unknown and a better understanding will require loss-of-function studies in vivo. Here we show that a novel class of chemically engineered oligonucleotides, termed 'antagomirs', are efficient and specific silencers of endogenous miRNAs in mice. Intravenous administration of antagomirs against miR-16, miR-122, miR-192 and miR-194 resulted in a marked reduction of corresponding miRNA levels in liver, lung, kidney, heart, intestine, fat, skin, bone marrow, muscle, ovaries and adrenals. The silencing of endogenous miRNAs by this novel method is specific, efficient and long-lasting. The biological significance of silencing miRNAs with the use of antagomirs was studied for miR-122, an abundant liver-specific miRNA. Gene expression and bioinformatic analysis of messenger RNA from antagomir-treated animals revealed that the 3' untranslated regions of upregulated genes are strongly enriched in miR-122 recognition motifs, whereas downregulated genes are depleted in these motifs. Analysis of the functional annotation of downregulated genes specifically predicted that cholesterol biosynthesis genes would be affected by miR-122, and plasma cholesterol measurements showed reduced levels in antagomir-122-treated mice. Our findings show that antagomirs are powerful tools to silence specific miRNAs in vivo and may represent a therapeutic strategy for silencing miRNAs in disease.

Highly efficient in vivo agonist-induced internalization of sst2 receptors in somatostatin target tissues

The successful peptide receptor imaging of tumors, as exemplified for somatostatin receptors, is based on the overexpression of peptide receptors in selected tumors and the high-affinity binding to these tumors of agonist radioligands that are subsequently internalized into the tumor cells in which they accumulate. Although in vitro studies have shown ample evidence that the ligand-receptor complex is internalized, in vivo evidence of agonist-induced internalization of peptide receptors, such as somatostatin receptors, is missing. METHODS: Rats subcutaneously transplanted with the somatostatin receptor subtype 2 (sst(2))-expressing AR42J tumor cells were treated with intravenous injections of various doses of the sst(2) agonist [Tyr(3), Thr(8)]-octreotide (TATE) or of the sst(2) antagonist 1,4,7,10-tetraazacyclododecane-N,N',N'',N''',-tetraacetic acid (DOTA)-Bass and were sacrificed at various times ranging from 2.5 min to 24 h after injection. The tumors and pancreas were then removed from each animal. All tissue samples were processed for sst(2) immunohistochemistry using sst(2)-specific antibodies. RESULTS: Compared with the sst(2) receptors in untreated animals, which localized at the plasma membrane in pancreatic and AR42J tumor cells, the sst(2) receptors in treated animals are detected intracellularly after an intravenous injection of the agonist TATE. Internalization is fast, as the receptors are already internalizing 2.5 min after TATE injection. The process is extremely efficient, as most of the cell surface receptors internalize into the cell and are found in endosomelike structures after TATE injection. The internalization is most likely reversible, because 24 h after injection the receptors are again found at the cell surface. The process is also agonist-dependent, because internalization is seen with high-affinity sst(2) agonists but not with high-affinity sst(2) antagonists. The same internalization properties are seen in pancreatic and AR42J tumor cells. They can further be confirmed in vitro in human embryonic kidney-sst(2) cells, with an immunofluorescence microscopy-based sst(2) internalization assay. CONCLUSION: These animal data strongly indicate that the process of in vivo sst(2) internalization after agonist stimulation is fast, extremely efficient, and fully functional under in vivo conditions in neoplastic and physiologic sst(2) target tissues. This molecular process is, therefore, likely to be responsible for the high and long-lasting uptake of sst(2) radioligands seen in vivo in sst(2)-expressing tumors.

Probing the function of ionotropic and G protein-coupled receptors in surface-confined membranes

This article reports on recent electrical and optical techniques for investigating cellular signaling reactions in artificial and native membranes immobilized on solid supports. The first part describes the formation of planar artificial lipid bilayers on gold electrodes, which reveal giga-ohm electrical resistance and the insertion and characterization of ionotropic receptors therein. These membranes are suited to record a few or even single ion channels by impedance spectroscopy. Such tethered membranes on planar arrays of microelectrodes offer mechanically robust, long-lasting measuring devices to probe the influence of different chemistries on biologically important ionotropic receptors and therefore will have a future impact to probe the function of channel proteins in basic science and in biosensor applications. In a second part, we present complementary approaches to form inside-out native membrane sheets that are immobilized on micrometer-sized beads or across submicrometer-sized holes machined in a planar support. Because the native membrane sheets are plasma membranes detached from live cells, these approaches offer a unique possibility to investigate cellular signaling processes, such as those mediated by ionotropic or G protein-coupled receptors, with original composition of lipids and proteins.

[Second victim : Critical incident stress management in clinical medicine]

BACKGROUND Critical incidents in clinical medicine can have far-reaching consequences on patient health. In cases of severe medical errors they can seriously harm the patient or even lead to death. The involvement in such an event can result in a stress reaction, a so-called acute posttraumatic stress disorder in the healthcare provider, the so-called second victim of an adverse event. Psychological distress may not only have a long lasting impact on quality of life of the physician or caregiver involved but it may also affect the ability to provide safe patient care in the aftermath of adverse events. METHODS A literature review was performed to obtain information on care giver responses to medical errors and to determine possible supportive strategies to mitigate negative consequences of an adverse event on the second victim. An internet search and a search in Medline/Pubmed for scientific studies were conducted using the key words "second victim, "medical error", "critical incident stress management" (CISM) and "critical incident stress reporting system" (CIRS). Sources from academic medical societies and public institutions which offer crisis management programs where analyzed. The data were sorted by main categories and relevance for hospitals. Analysis was carried out using descriptive measures. RESULTS In disaster medicine and aviation navigation services the implementation of a CISM program is an efficient intervention to help staff to recover after a traumatic event and to return to normal functioning and behavior. Several other concepts for a clinical crisis management plan were identified. CONCLUSIONS The integration of CISM and CISM-related programs in a clinical setting may provide efficient support in an acute crisis and may help the caregiver to deal effectively with future error events and employee safety.