Ionic basis of the caesium-induced depolarisation in rat supraoptic nucleus neurones.

1. The effects of external Cs(+) on magnocellular neurosecretory cells were studied during intracellular recordings from 93 supraoptic nucleus neurones in superfused explants of rat hypothalamus. 2.

Peptidergic excitation of supraoptic nucleus neurons: involvement of stretch-inactivated cation channels.

Although the primary stimulus regulating vasopressin (VP) release is a change in systemic osmolality, other physiological parameters are known to affect VP secretion or modulate the osmotic control over its release. Neuropeptides feature prominently in afferents underlying the central regulation of the VP-releasing magnocellular neurosecretory cells (MNCs). Although little is yet known of the circumstances under which peptides are released onto MNCs, previous studies have shown that a common response profile to exogenous peptide application is a slow excitation that seems to result from the activation of a nonselective cation conductance.

Ovariectomy up-regulates neuronal neurofilament light chain mRNA expression with regional and temporal specificity.

Estrogens can influence the survival, plasticity and function of many adult neurons. Many of these effects, such as neurite outgrowth and increased dendritic spine density, are mediated by changes in neuronal cytoskeletal architecture. Since neurofilament proteins play a key role in the maintenance and remodeling of the neuronal cytoskeleton, we postulated that changes in neurofilament light chain mRNA may parallel some of the alterations in neuronal architecture which follow bilateral ovariectomy.

Successful retrieval and function of lungs from non-heart-beating donors.

Background: Lung transplantation has been used effectively as a therapeutic tool in end-stage pulmonary diseases, but organ shortages have restricted its use. There is growing interest in alternative organ sources such as organs from circulation-arrested cadavers, so called non-heart-beating donors.

Methods: We examined the effects of postmortem rapid in situ cadaver lung cooling by bilateral chest cavity flushing (group 2) and by pulmonary artery flush through right heart catheterization followed by pleural cavity flushing (group 3) on pulmonary function and morphology in a rabbit non-heart-beating donor model.

Topological specificity in reinnervation of the superior colliculus by regenerated retinal ganglion cell axons in adult hamsters.

In normal rodents there is a precise topology of the retinocollicular projection, the nasotemporal and ventrodorsal axes of the retina being respectively projected onto the caudorostral and mediolateral axes of the contralateral superior colliculus (SC). We evaluated the distribution of regenerated retinal ganglion cell (RGC) axon terminals in the SC of adult hamsters in which an unbranched peripheral nerve graft was directed from the retina to the contralateral SC. Responses to visual stimulation of individual RGCs were recorded from terminal arbors of their regenerated axons in the reinnervated SC.

A community rheumatology practice offers an educational experience comparable to that of a university tertiary care center.

Objective: To compare the teaching value of rheumatology patients seen in either a community rheumatology practice or in a tertiary care university center.

Methods: Consecutive patients seen at the 2 sites over a one month period were assessed for rheumatology diagnosis, complexity of rheumatologic disease, and treatments received, including number of interventions performed. The overall pedagogic value of the encounter was rated by the rheumatologist for both medical students and postgraduate trainees.

Reciprocal actions of interleukin-6 and brain-derived neurotrophic factor on rat and mouse primary sensory neurons.

In low-density, serum-free cultures of neurons from embryonic rat dorsal root ganglia, interleukin-6 supports the survival of less than one third of the neurons yet virtually all of them bear interleukin-6 alpha-receptors. A finding that might explain this selectivity is that interleukin-6 acts on sensory neurons in culture through a mechanism requiring endogenous brain-derived neurotrophic factor. Antibodies or a trkB fusion protein that block the biological activity of brain-derived neurotrophic factor synthesized by dorsal root ganglion neurons also block the survival-promoting actions of interleukin-6 on these neurons.

Inhibition of cyclooxygenase-2 improves cardiac function in myocardial infarction.

Induction of cyclooxygenase-2 (COX-2) in ischemic myocardium is thought to increase the production of proinflammatory prostanoids and contribute significantly to the ischemic inflammation. Left ventricular myocardial infarction (MI) was created by ligating the left coronary artery in Lewis rats. Hemodynamic measurements at 4 weeks showed better cardiac function in the group treated with a selective COX-2 inhibitor (DFU; 5 mg/kg/day) for 2 weeks after induction of MI compared to the vehicle treated group.

Excitatory role of the hyperpolarization-activated inward current in phasic and tonic firing of rat supraoptic neurons.

The properties and functional roles of the hyperpolarization-activated inward current (I(H)) in magnocellular neurosecretory cells (MNCs) were investigated during sharp microelectrode recordings from supraoptic neurons in superfused explants of rat hypothalamus. Under current clamp, voltage responses to hyperpolarizing current pulses featured depolarizing sags that were abolished by the I(H) blocker ZD 7288. Under voltage clamp, subtraction of current responses to hyperpolarizing steps recorded in the absence and presence of ZD 7288 was used to investigate the properties of I(H).

Excitatory peptides and osmotic pressure modulate mechanosensitive cation channels in concert.

Behavioral and neuroendocrine responses underlying systemic osmoregulation are synergistically controlled by osmoreceptors and neuropeptides released within the hypothalamus. Although mechanisms underlying osmoreception are understood, the cellular basis for the integration of osmotic and peptidergic signals remains unknown. Here we show that the excitatory effects of angiotensin II, cholecystokinin and neurotensin on supraoptic neurosecretory neurons are due to the stimulation of the stretch-inactivated cation channels responsible for osmoreception.

Psychosocial correlates of prepartum and postpartum depressed mood.

Background: The aim of the present study was to delineate the influence of maternal stress, social support and coping styles on depressed mood during pregnancy and the early postpartum period.

Methods: Beginning in the third month of pregnancy, data on numerous variables including daily stress (Hassles), state-anxiety (STAI-state), pregnancy-specific stress (PEQ) and depressed mood (DACL) were collected monthly. In each trimester social support (SSQ), coping strategies (CISS) and pregnancy progress were assessed.

Coincident detection of CSF Na+ and osmotic pressure in osmoregulatory neurons of the supraoptic nucleus.

Behavioral and neuroendocrine responses underlying systemic osmoregulation are under the concerted control of centrally located osmoreceptors and cerebrospinal fluid (CSF) Na+ concentration ([Na+]) detectors. Although the process underlying osmoreception is understood, the mechanism by which [Na+] is detected and integrated with cellular information derived from osmoreceptors is unknown. Here, we show that shifts in extracellular [Na+] ([Na+]0) cause proportional changes in the relative Na+ permeability of mechanosensitive cation channels responsible for signal transduction in the osmosensory neurons of the supraoptic nucleus.

Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial.

We have studied the characteristics of bone ingrowth of a new porous tantalum biomaterial in a simple transcortical canine model using cylindrical implants 5 x 10 mm in size. The material was 75% to 80% porous by volume and had a repeating arrangement of slender interconnecting struts which formed a regular array of dodecahedron-shaped pores. We performed histological studies on two types of material, one with a smaller pore size averaging 430 microm at 4, 16 and 52 weeks and the other with a larger pore size averaging 650 microm at 2, 3, 4, 16 and 52 weeks.

Kappa-opioid receptor activation inhibits post-spike depolarizing after-potentials in rat supraoptic nucleus neurones in vitro.

Endogenous agonists acting at kappa-opioid receptors modulate the discharge activity of hypothalamic supraoptic nucleus vasopressin cells in vivo. Phasic activity in vasopressin cells is known to depend critically on intrinsic mechanisms involving post-spike depolarizing after-potentials and we hypothesized that inhibition of phasic bursting by an endogenous kappa-agonist may result from reducing the magnitude of depolarizing after-potentials. To investigate this possibility, intracellular sharp electrode recordings were obtained from supraoptic nucleus cells impaled in superfused explants of rat hypothalamus.

Uterine adenomyosis: endovaginal US and MR imaging features with histopathologic correlation.

Uterine adenomyosis is a common gynecologic condition that is characterized by the presence of heterotopic endometrial glands and stroma in the myometrium with adjacent smooth muscle hyperplasia. The histopathologic features of adenomyosis are varied and contribute to its imaging appearance. The accompanying smooth muscle hyperplasia produces the typical gross appearance of adenomyosis and corresponds to areas of decreased echogenicity at endovaginal ultrasonography (US) and areas of decreased signal intensity at magnetic resonance (MR) imaging.

Endothelial expression of endothelial nitric oxide synthase and endothelin-1 in human coronary artery disease. Specific reference to underlying lesion.

Nitric oxide and endothelin-1 (ET-1) are two major endothelium-derived factors with opposing effects on the function and structure of the vessel wall. We investigated the endothelial expression of endothelial nitric oxide synthase (eNOS) and ET-1 in coronary artery disease (CAD) with special reference to the types of underlying lesions. Immunohistochemistry and in situ hybridization were performed in coronary arteries of heart transplant recipients with (n = 16) and without (n = 11) CAD.

Nature of the retrograde signal from injured nerves that induces interleukin-6 mRNA in neurons.

In previous studies, interleukin-6 was shown to be synthesized in approximately one-third of lumbar dorsal root ganglion neurons during the first week after nerve transection. In present studies, interleukin-6 mRNA was found to be induced also in axotomized facial motor neurons and sympathetic neurons. The nature of the signal that induces interleukin-6 mRNA in neurons after nerve injury was analyzed.

Endothelin receptor antagonist improves pulmonary hemodynamics during lung ischemia/reperfusion injury.

Background: We have previously shown that elevated release of endothelin-1 is associated with increased pulmonary vascular resistance (PVR) immediately after reperfusion of the transplanted lung. In the present study, we investigated the effect of ET receptor blockage on pulmonary hemodynamics and function in an ex vivo lung reperfusion model after 6 hr of cold ischemia.

Methods: Eighteen rabbits were divided into three groups: no ischemia followed by 3 hr of reperfusion (group I) and 6 hr of cold ischemia followed by 3 hr of reperfusion with either blood (group II) or blood + SB209670 (mixed ETA/ETB receptor antagonist) (group III).

Density of transient K+ current influences excitability in acutely isolated vasopressin and oxytocin neurones of rat hypothalamus.

1. The transient outward K+ current (ITO) was studied using whole-cell recording in immunocytochemically identified oxytocin (OT; n = 23) and vasopressin (VP; n = 67) magnocellular neurosecretory cells (MNCs) acutely isolated from the supraoptic nucleus of adult rats. 2.

Heterogeneous expression and activity of endothelial and inducible nitric oxide synthases in end-stage human heart failure: their relation to lesion site and beta-adrenergic receptor therapy.

Background: Recent reports have suggested that excessive amounts of endogenous NO may contribute to the myocardial dysfunction and injury in heart failure. In the present report, we investigate the cellular expression and activity of endothelial (eNOS) and inducible (iNOS) NO synthase in failing human hearts with special reference to the underlying lesion and drug therapy.

Methods And Results: Myocardial tissues were obtained from 28 failing human hearts with various pathogeneses and 4 nonfailing hearts as controls.

Induction of cyclooxygenase-2 and activation of nuclear factor-kappaB in myocardium of patients with congestive heart failure.

Background: Chronic heart failure is associated with induction of secondary inflammatory mediators, including prostanoids. The latter exert diverse functional and morphological effects on cardiac myocytes. Induction of cyclooxygenase (COX), the enzyme responsible for generating prostanoids, requires activation of nuclear factor-kappaB (NF-kappaB).

Application of the lectin-dependent cell-mediated cytotoxicity assay to bronchoalveolar lavage fluid and venous blood samples collected from canine lung allografts.

One of the major obstacles in postoperative management of lung transplant recipients is differentiating between rejection and infection episodes. In addition, there are no reliable methods routinely to monitor lung allografts to ascertain that they are well tolerated by the host. Conventional noninvasive methods such as chest roentgenographs, radio nuclide perfusion scans, and pulmonary function tests used in conjunction with clinical assessment have been shown to be nonspecific (1,2).

Delay of CNTF decrease following peripheral nerve injury in C57BL/Wld mice.

In peripheral nerves, ciliary neurotrophic factor (CNTF) is localized to a subset of Schwann cells and is decreased in synthesis during Wallerian degeneration. This pattern of expression is similar to that of myelin protein genes. In the present study, C57BL/Wld mice, which exhibit delayed Wallerian degeneration, were used to determine the role of axonal contact on the regulation of CNTF synthesis.

Engineering issues and wear performance of metal on metal hip implants.

A major concern in total hip arthroplasty is the generation of polyethylene wear particles at the articulating surfaces and resulting macrophage mediated periimplant osteolysis. There is renewed interest in metal on metal bearings as a solution to this problem in view of their potential for greatly improved wear performance. Using a commercially available hip simulator, the wear performance of metal on metal femoral head and acetabular cup combinations was evaluated and various parameters affecting metal on metal implant wear were identified.