Visualization of Partial Exocytotic Content Release and Chemical Transport into Nanovesicles in Cells.

For decades, "all-or-none" and "kiss-and-run" were thought to be the only major exocytotic release modes in cell-to-cell communication, while the significance of partial release has not yet been widely recognized and accepted owing to the lack of direct evidence for exocytotic partial release. Correlative imaging with transmission electron microscopy and NanoSIMS imaging and a dual stable isotope labeling approach was used to study the cargo status of vesicles before and after exocytosis; demonstrating a measurable loss of transmitter in individual vesicles following stimulation due to partial release. Model secretory cells were incubated with C-labeled l-3,4-dihydroxyphenylalanine, resulting in the loading of C-labeled dopamine into their vesicles.

Arginine-vasopressin mediates counter-regulatory glucagon release and is diminished in type 1 diabetes.

Insulin-induced hypoglycemia is a major treatment barrier in type-1 diabetes (T1D). Accordingly, it is important that we understand the mechanisms regulating the circulating levels of glucagon. Varying glucose over the range of concentrations that occur physiologically between the fed and fuel-deprived states (8 to 4 mM) has no significant effect on glucagon secretion in the perfused mouse pancreas or in isolated mouse islets (in vitro), and yet associates with dramatic increases in plasma glucagon.

The evidence for open and closed exocytosis as the primary release mechanism.

Exocytosis is the fundamental process by which cells communicate with each other. The events that lead up to the fusion of a vesicle loaded with chemical messenger with the cell membrane were the subject of a Nobel Prize in 2013. However, the processes occurring after the initial formation of a fusion pore are very much still in debate.

Cholesterol Alters the Dynamics of Release in Protein Independent Cell Models for Exocytosis.

Neurons communicate via an essential process called exocytosis. Cholesterol, an abundant lipid in both secretory vesicles and cell plasma membrane can affect this process. In this study, amperometric recordings of vesicular dopamine release from two different artificial cell models created from a giant unilamellar liposome and a bleb cell plasma membrane, show that with higher membrane cholesterol the kinetics for vesicular release are decelerated in a concentration dependent manner.

Determining conserved metabolic biomarkers from a million database queries.

Motivation: Metabolite databases provide a unique window into metabolome research allowing the most commonly searched biomarkers to be catalogued. Omic scale metabolite profiling, or metabolomics, is finding increased utility in biomarker discovery largely driven by improvements in analytical technologies and the concurrent developments in bioinformatics. However, the successful translation of biomarkers into clinical or biologically relevant indicators is limited.

Robust and fragile aspects of cortical blood flow in relation to the underlying angioarchitecture.

We review the organizational principles of the cortical vasculature and the underlying patterns of blood flow under normal conditions and in response to occlusion of single vessels. The cortex is sourced by a two-dimensional network of pial arterioles that feeds a three-dimensional network of subsurface microvessels in close proximity to neurons and glia. Blood flow within the surface and subsurface networks is largely insensitive to occlusion of a single vessel within either network.

Two modes of exocytosis in an artificial cell.

The details of exocytosis, the vital cell process of neuronal communication, are still under debate with two generally accepted scenarios. The first mode of release involves secretory vesicles distending into the cell membrane to release the complete vesicle contents. The second involves partial release of the vesicle content through an intermittent fusion pore, or an opened or partially distended fusion pore.

Composition based strategies for controlling radii in lipid nanotubes.

Nature routinely carries out small-scale chemistry within lipid bound cells and organelles. Liposome-lipid nanotube networks are being developed by many researchers in attempt to imitate these membrane enclosed environments, with the goal to perform small-scale chemical studies. These systems are well characterized in terms of the diameter of the giant unilamellar vesicles they are constructed from and the length of the nanotubes connecting them.

Evaluating the diffusion coefficient of dopamine at the cell surface during amperometric detection: disk vs ring microelectrodes.

During exocytosis, small quantities of neurotransmitters are released by the cell. These neurotransmitters can be detected quantitatively using electrochemical methods, principally with disk carbon fiber microelectrode amperometry. An exocytotic event then results in the recording of a current peak whose characteristic features are directly related to the mechanisms of exocytosis.

Amperometric post spike feet reveal most exocytosis is via extended kiss-and-run fusion.

The basis for communication between nerve cells lies in the process of exocytosis, the fusion of neurotransmitter filled vesicles with the cell membrane resulting in release of the signaling molecules. Even though much is known about this process, the extent that the vesicles are emptied upon fusion is a topic that is being debated. We have analyzed amperometric peaks corresponding to release at PC12 cells and find stable plateau currents during the decay of peaks, indicating closing of the vesicle after incomplete release of its content.

Infant feeding practices in Bhaktapur, Nepal: a cross-sectional, health facility based survey.

Background: Promotion of proper breastfeeding practices for the first six months of life is the most cost-effective intervention for reducing childhood morbidity and mortality. However, the adherence to breastfeeding recommendations in many developing countries is not satisfactory. The aims of the study were to determine breastfeeding and infant feeding patterns at nine months of age and to assess factors influencing exclusive breastfeeding practices.

Temporal resolution in electrochemical imaging on single PC12 cells using amperometry and voltammetry at microelectrode arrays.

Carbon-fiber-microelectrode arrays (MEAs) have been utilized to electrochemically image neurochemical secretion from individual pheochromocytoma (PC12) cells. Dopamine release events were electrochemically monitored from seven different locations on single PC12 cells using alternately constant-potential amperometry and fast-scan cyclic voltammetry (FSCV). Cyclic voltammetry, when compared to amperometry, can provide excellent chemical resolution; however, spatial and temporal resolution are both compromised.

Estradiol inhibits depolarization-evoked exocytosis in PC12 cells via N-type voltage-gated calcium channels.

Fast neuromodulatory effects of 17-β-estradiol (E2) on cytosolic calcium concentration ([Ca(2+)](i)) have been reported in many cell types, but little is known about its direct effects on vesicular neurotransmitter secretion (exocytosis). We examined the effects of E2 on depolarization-evoked [Ca(2+)](i) in PC12 cells using fluorescence measurements. Imaging of [Ca(2+)](i) with FURA-2 revealed that depolarization-evoked calcium entry is inhibited after exposure to 10 nM and 10 μM E2.

Electrochemical probes for detection and analysis of exocytosis and vesicles.

Unraveling the mechanistic details of neurotransmitter exocytosis is arguably among the most important molecular problems in neuroscience today. Investigations at single cells, particularly with electrochemical methods, have given unique chemical and biological insight into this process at the fundamental level. The rapid response time (submillisecond) of microelectrodes makes them well suited for monitoring the dynamic process of exocytosis.

The involvement of Aeromonas salmonicida virulence factors in bacterial translocation across the rainbow trout, Oncorhynchus mykiss (Walbaum), intestine.

The pathogenic bacterium Aeromonas salmonicida is the causative agent of furunculosis, a lethal disease in salmonids. The mode of lateral transmission has not been conclusively defined, but A. salmonicida is able to translocate across the intestinal epithelium of salmonids, making the intestinal route a probable candidate.

Avidity of tetanus and Hib antibodies after childhood acute lymphoblastic leukaemia - implications for vaccination strategies.

Aim: To investigate the possible relationship between serum levels and avidities of antibodies against tetanus toxoid (TT) and Haemophilus influenzae type b (Hib) in children that were vaccinated after treatment for childhood acute lymphoblastic leukaemia (ALL).

Methods: The study groups were 31 paediatric patients with ALL and 18 healthy controls. All subjects were vaccinated with TT and a protein conjugated Hib vaccine.

Long-term results in children with AML: NOPHO-AML Study Group--report of three consecutive trials.

In all, 447 children with acute myeloid leukaemia (AML) have been treated on three consecutive NOPHO studies from July 1984 to December 2001. NOPHO-AML 84 was of moderate intensity with an induction of three courses of cytarabine, 6-thioguanine and doxorubicin followed by four consolidation courses with high-dose cytarabine. The 5-year event-free survival (EFS), disease free survival (DFS) and overall survival (OS) were 29, 37 and 38%.

Multiple lymph node metastases in a boy with primary testicular carcinoid, despite negative preoperative imaging procedures.

A testicular tumor in a 12-year-old boy proved to be a carcinoid tumor. An extensive investigation including a computed tomographic scan of the abdominal and pelvic region as well as both 123I-labeled metaiodobenzylguanidine and 111In-coupled octreotide scintigraphy was normal. Because histopathologic examination of the primary surgical specimen revealed tumor growth in the resection border of the spermatic vessels, a second operation with unilateral lymph node dissection was performed.

Interferon gamma and tumour necrosis factor alpha in relation to anaemia and prognosis in childhood cancer.

Unlabelled: This study examined whether the initial plasma levels of tumour necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) in 131 children with newly diagnosed cancer were associated with haematopoietic suppression, and whether plasma levels of TNFalpha or haemoglobin at diagnosis affects long-term prognosis in childhood acute lymphoblastic leukaemia (ALL).

Conclusions: IFNgamma, and possibly also TNFalpha, were related to anaemia in children with solid tumours. Neither TNFalpha levels nor Hb levels were associated with increased risk of ALL relapse.

[Acute lymphatic leukemia in Swedish children 1968-2001. The marked improvement of the survival can be ascribed to successful treatment].

This is a survey of acute lymphoblastic leukemia (ALL) in Swedish children from 1968 to 2001. The survival has increased from a few per cent to more than 80 per cent of children with ALL in these national complete patient materials. Changes in diagnosis and treatment are discussed as well as the importance of supportive care.

Immune reconstitution after childhood acute lymphoblastic leukemia is most severely affected in the high risk group.

Objective: The aim was to examine the immune reconstitution after current chemotherapy for childhood ALL, with a special focus on finding immunologic variables that predict a poor immune response to vaccinations.

Procedure: In a cross-sectional study of 31 children after treatment with the NOPHO ALL-1992 protocol peripheral blood lymphocyte subsets, T- and B-cell function in vitro and serum immunoglobulins (Ig) were measured. All patients were examined once, at 1 or at 6 months after cessation of chemotherapy, immediately before vaccination with DT and Hib.

Intensive treatment for childhood acute lymphoblastic leukemia reduces immune responses to diphtheria, tetanus, and Haemophilus influenzae type b.

Objectives: Immunity to diphtheria toxoid (D), tetanus toxoid (T), and Haemophilus influenzae type b (Hib) is affected in children with acute lymphoblastic leukemia (ALL). The aims were to examine immunity and to compare the response to immunization at 1 or 6 months after treatment.

Methods: Thirty-one patients were immunized with DT and conjugated Hib vaccine (ActHib) at 1 month or 6 months after treatment of ALL with the NOPHO 92 protocol.

Feeding patterns, diarrhoeal illness and linear growth in 0-24-month-old children.

The aim was to study the impact of simple healthcare interventions in 0-24-month-old children living in rural communities outside Lahore, Pakistan. Newborns belonging to four birth cohorts were followed monthly from 0-24 months of age living in rural communities. Three cohorts were from the same village: Cohort A (1984-1987), n = 485; Cohort B (1990-1992), n = 544; and Cohort C (1995-1997), n = 518.

Outcome of children with high-risk acute lymphoblastic leukemia (HR-ALL): Nordic results on an intensive regimen with restricted central nervous system irradiation.

Background: Improvement in outcome of childhood high-risk (HR) ALL was sought with a very intensive Nordic protocol leaving most patients without CNS-RT.

Methods: A total of 426 consecutive children entered the NOPHO-92 HR-ALL program. HR criteria included WBC > or =50 x 10(9)/L, CNS or testicular involvement, T-cell, lymphomatous features, t(9;22), t(4;11), or slow response.