Atomic-scale STM experiments on semiconductor surfaces: towards molecular nanomachines.

The electronic or quantum control of individual molecules with the scanning tunnelling microscope offers exciting perspectives on operating molecular nanomachines. This implies the use of semiconductor surfaces rather than metallic surfaces which would rapidly quench the electronic excitations. We review recent results illustrating the state of the art and the main problems which need to be solved: the choice, design and properties of functionalized organic molecules on semiconductor surfaces; the control of the inelastic electronic channels through a single molecule; and the search for well-controlled atomic-scale wide-band-gap semiconductor surfaces.

Determinants of liposome fusion mediated by synaptic SNARE proteins.

Synaptic exocytosis requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins syntaxin 1, SNAP-25, and synaptobrevin (VAMP). Assembly of the SNAREs into a stable core complex is supposed to catalyze membrane fusion, and proteoliposomes reconstituted with synaptic SNARE proteins spontaneously fuse with each other. We now show that liposome fusion mediated by synaptic SNAREs is inhibited by botulinum neurotoxin E (BoNT/E) but can be rescued by supplementing the C-terminal portion of SNAP-25.

The claudin-like megatrachea is essential in septate junctions for the epithelial barrier function in Drosophila.

Vertebrate claudin proteins are integral components of tight junctions, which function as paracellular diffusion barriers in epithelia. We identified Megatrachea (Mega), a Drosophila transmembrane protein homologous to claudins, and show that it acts in septate junctions, the corresponding structure of invertebrates. Our analysis revealed that Mega has transepithelial barrier function similar to the claudins.

Cases from the Osler Medical Service at Johns Hopkins University. Antiglomerular basement membrane disease.

A 47-year-old Taiwanese man with no notable medical history was admitted with low-grade fevers and night sweats that had persisted for 5 to 6 weeks. An extensive investigation at another hospital could not determine the cause of the fevers, but documented acute renal failure with a blood urea nitrogen level of 60 mg/dL and a serum creatinine level of 5.6 mg/dL.

Relationships and distinctions in iron-regulatory networks responding to interrelated signals.

Specialized cDNA-based microarrays (IronChips) were developed to investigate complex physiological gene-regulatory patterns in iron metabolism. Approximately 115 human cDNAs were strategically selected to represent genes involved either in iron metabolism or in interlinked pathways (eg, oxidative stress, nitric oxide [NO] metabolism, or copper metabolism), and were immobilized on glass slides. HeLa cells were treated with iron donors or iron chelators, or were subjected to oxidative stress (H(2)O(2)) or NO (sodium nitroprusside).

Rab3D is not required for exocrine exocytosis but for maintenance of normally sized secretory granules.

Rab3D, a member of the Rab3 subfamily of the Rab/ypt GTPases, is expressed on zymogen granules in the pancreas as well as on secretory vesicles in mast cells and in the parotid gland. To shed light on the function of Rab3D, we have generated Rab3D-deficient mice. These mice are viable and have no obvious phenotypic changes.

Loss of the zymogen granule protein syncollin affects pancreatic protein synthesis and transport but not secretion.

Syncollin is a small protein that is abundantly expressed in pancreatic acinar cells and that is tightly associated with the lumenal side of the zymogen granule membrane. To shed light on the hitherto unknown function of syncollin, we have generated syncollin-deficient mice. The mice are viable and show a normal pancreatic morphology as well as normal release kinetics in response to secretagogue stimulation.

SNAREs are concentrated in cholesterol-dependent clusters that define docking and fusion sites for exocytosis.

During exocytosis, SNARE proteins of secretory vesicles interact with the corresponding SNARE proteins in the plasmalemma to initiate the fusion reaction. However, it is unknown whether SNAREs are uniformly distributed in the membrane or whether specialized fusion sites exist. Here we report that in the plasmalemma, syntaxins are concentrated in 200 nm large, cholesterol-dependent clusters at which secretory vesicles preferentially dock and fuse.

Quantal release of serotonin.

We have studied the origin of quantal variability for small synaptic vesicles (SSVs) and large dense-cored vesicles (LDCVs). As a model, we used serotonergic Retzius neurons of leech that allow for combined amperometrical and morphological analyses of quantal transmitter release. We find that the transmitter amount released by a SSV varies proportionally to the volume of the vesicle, suggesting that serotonin is stored at a constant intravesicular concentration and is completely discharged during exocytosis.

Exocytosis requires asymmetry in the central layer of the SNARE complex.

Assembly of SNAREs (soluble N:-ethylmaleimide- sensitive factor attachment protein receptors) mediates membrane fusions in all eukaryotic cells. The synaptic SNARE complex is represented by a twisted bundle of four alpha-helices. Leucine zipper-like layers extend through the length of the complex except for an asymmetric and ionic middle layer formed by three glutamines (Q) and one arginine (R).

The SNARE Vti1a-beta is localized to small synaptic vesicles and participates in a novel SNARE complex.

Specific soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) proteins are required for different membrane transport steps. The SNARE Vti1a has been colocalized with Golgi markers and Vti1b with Golgi and the trans-Golgi network or endosomal markers in fibroblast cell lines. Here we study the distribution of Vti1a and Vti1b in brain.

Differential tolerance induction by lipoarabinomannan and lipopolysaccharide in human macrophages.

Various bacterial cell wall components have been shown to induce hyporesponsiveness in macrophages (MAC). Here, mycobacterial glycolipids were employed to determine whether they induce a state of 'tolerance/hyporesponsiveness' in MAC in vitro in order to assess whether mycobacterial components negatively affect the immune response to Mycobacterium tuberculosis. Arabinosylated lipoarabinomannan (ARA-LAM) stimulated hyporesponsiveness by reducing TNF-alpha, GM-CSF, G-CSF, IL-10, and IL-6 release similarly to LPS, but caused no changes in IL-8 secretion.

Immunoisolation of GABA-specific synaptic vesicles defines a functionally distinct subset of synaptic vesicles.

Synaptic vesicles from mammalian brain are among the best characterized trafficking organelles. However, so far it has not been possible to characterize vesicle subpopulations that are specific for a given neurotransmitter. Taking advantage of the recent molecular characterization of vesicular neurotransmitter transporters, we have used an antibody specific for the vesicular GABA transporter (VGAT) to isolate GABA-specific synaptic vesicles.

A cell-free system for regulated exocytosis in PC12 cells.

We have developed a cell-free system for regulated exocytosis in the PC12 neuroendocrine cell line. Secretory vesicles were preloaded with acridine orange in intact cells, and the cells were sonicated to produce flat, carrier-supported plasma membrane patches with attached vesicles. Exocytosis resulted in the release of acridine orange which was visible as a disappearance of labeled vesicles and, under optimal conditions, produced light flashes by fluorescence dequenching.

Ultrastructural localization of nonstructural and coat proteins of 19 potyviruses using antisera to bacterially expressed proteins of plum pox potyvirus.

Antisera to the bacterially expressed nonstructural proteins (NSP) HC-Pro, CI, NIa, and NIb and the coat protein (CP) of plum pox potyvirus (PPV) were used for analysing the composition of virus-induced cytoplasmic and nuclear inclusions by electron microscopy. The antisera reacted with NSP and CP of PPV on immunogold-labelled ultrathin sections. Antiserum to CP reacted with virions of seven out of 18 other potyviruses.

A comparative analysis of cytokine production and tolerance induction by bacterial lipopeptides, lipopolysaccharides and Staphyloccous aureus in human monocytes.

Monocytes (MO) and macrophages (MAC) are important producers of cytokines involved in the pathophysiology of bacterial sepsis. Most studies concentrate on the effects of bacterial lipopolysaccharides (LPS) regarding the induction of cytokine gene expression and secretion in MO/MAC. Here we report that besides LPS, the synthetic lipoprotein analogue lipopeptide N-palmitoyl-S-(2,3-bis(palmitoyl)-(2RS)-propyl)-(R)-cysteinyl-alanyl- glycine (Pam3-Cys-Ala-Gly), another component of the outer membrane of Gram-negative bacteria, as well as heat-killed Staphyloccocus aureus (S.

Chemokine secretion by human polymorphonuclear granulocytes after stimulation with Mycobacterium tuberculosis and lipoarabinomannan.

Macrophages (MAC) and polymorphonuclear granulocytes (PNG) are professional phagocytes which perform essential functions in antibacterial defense. The intracellular bacterium Mycobacterium tuberculosis persists and replicates in resting macrophages. Although it is generally assumed that activated MAC are central to protection against M.

Interleukin-12 secretion by Mycobacterium tuberculosis-infected macrophages.

Infection with Mycobacterium tuberculosis or phagocytosis of large latex beads induced interleukin-12 (IL-12) production in macrophages. In contrast, tumor necrosis factor (TNF) was produced only in response to M. tuberculosis infection, not after phagocytosis of latex beads.

Debridement by operators with varying degrees of experience: a comparative study on manikins.

The treatment of periodontally diseased root surfaces with power-driven instruments is becoming increasingly important as an alternative to the use of hand instruments. Root surfaces of artificial teeth on a manikin were debrided under simulated flap operation conditions to determine if effectiveness was dependent on the instrument used (curettes or a modified sonic scaler tip) and/or the operator's degree of experience. Two quadrants were treated with each instrument.

Comparative serum estradiol profiles from a new once-a-week transdermal estradiol patch and a twice-a-week transdermal estradiol patch.

Two identical open-label, randomized crossover studies were conducted to compare serum estradiol profiles from the new 12.5- and 25-cm2 once-a-week adhesive patches with those from the 10- and 20-cm2 commercially available twice-a-week Estraderm patches when applied as directed during a 1-week patch-wear period. Both studies were conducted in healthy postmenopausal women; serum estradiol levels were determined by gas chromatography/mass spectroscopy (GC/MS).

Nursing management of patients with brain injury requiring one-on-one care.

Patients with traumatic brain injury currently constitute a major portion of the rehabilitation population. Although agitated, restless, and wandering behavior is an expected stage in the recovery process of these patients, issues involving the patient's and the staff's safety can arise when these behaviors are excessive and hard to control. In addition, patients may have difficulty achieving their rehabilitation goals because of these behaviors.

Fish consumption by Vietnamese women immigrants: a comparison of methods.

In this study, the measurement properties of an interview-administered fish consumption frequency questionnaire, used with a pilot study of 20 Vietnamese immigrant women, were described. Reproducibility across two summer interviews and one winter interview for estimates of seasonal and yearly intake of Great Lakes fish was moderate (intraclass correlation coefficients: .51-.

Bioequivalence Comparison of Two Drug-in-Adhesive Transdermal Nitroglycerin Patches.

Plasma concentrations of nitroglycerin, 1,2-dinitroglycerin and 1,3-dinitroglycerin in 50 healthy male subjects who received single 24-h applications of two 0.6 mg/h drug-in-adhesive transdermal nitroglycerin patch formulations were compared for the purpose of establishing bioequivalence. The rates of appearance and elimination of nitroglycerin and both dinitro metabolites were the same for both patch treatments.

Serum Estradiol and Estrone Levels During 3 Weeks of Alternate-Site and Same-Site Applications of a Once-A-Week Drug-in-Adhesive Transdermal Estradiol Patch.

This open-label, randomized crossover trial was conducted in healthy postmenopausal women to characterize the serum estradiol and estrone profiles from a once-a-week transdermal estradiol patch applied repeatedly to the same site or to alternate sites on the abdomen over a 3-week period. Similar mean serum estradiol and estrone profiles and circulating estradiol:estrone ratios of approximately 1.0 were observed for both patch application regimes.

Immunolocalization and quantitation of acidic seminal fluid protein (aSFP) in ejaculated, swim-up, and capacitated bull spermatozoa.

Acidic seminal fluid protein (aSFP, 12.9 kDa), a major protein of bull seminal plasma, belongs to the spermadhesin protein family. Boar spermadhesins become bound to the sperm head's surface at ejaculation and are thought to play a role as capacitation factors and/or in gamete recognition and binding.