Wiring efficiency of a metallizable DNA linker for site-addressable nanobioelectronic assembly

We report the first demonstration of DNA oligonucleotide tags used to address the site-specific assembly of multiple redox enzymes onto spatially distinct regions of a nanoelectronic platform, establishing a direct electrical contact. The resulting system constitutes a multiplexed carbon nanotube-redox protein biosensor capable of detecting varying concentrations of several different substances in real time. The efficiency and robustness of the enzyme linking scheme is explored in detail, showing a high degree of preservation of enzymatic activity and an efficient electrical contact at the enzyme-nanoelectrode interface. While five proteins have been used as a demonstration in this study, there is virtually no limit to the number of enzymes that could be bound in parallel using this linking strategy, which is universally applicable to all proteins due to the simple conjugation chemistry involved. We further demonstrate metallization of the linker in the presence of a divalent metal cation, inducing elevated electron transfer efficiency relative to the native DNA link.     

Self-assembled virus-like particles with magnetic cores

Efficient encapsulation of functionalized spherical nanoparticles by viral protein cages was found to occur even if the nanoparticle is larger than the inner cavity of the native capsid. This result raises the intriguing possibility of reprogramming the self-assembly of viral structural proteins. The iron oxide nanotemplates used in this work are superparamagnetic, with a blocking temperature of about 250 K, making these virus-like particles interesting for applications such as magnetic resonance imaging and biomagnetic materials. Another novel feature of the virus-like particle assembly described in this work is the use of an anionic lipid micelle coat instead of a molecular layer covalently bound to the inorganic nanotemplate. Differences between the two functionalization strategies are discussed.     

Comparison of three different methods for measuring classical pathway complement activity

A 30-year-old man was referred as an acute case for keratitis. Two days earlier he had had photorefractive keratectomy for myopia at another clinic; a bandage contact lens was placed over the eye, but prophylactic antibiotics were not prescribed. The keratitis was treated with gentamicin sulfate (Garamycin) and chloramphenicol eyedrops. Scrapings from the cornea showed nonhemolytic streptococci. Two and a half months later, visual acuity was finger counting because of gross distortion of the corneal contour. The combination of a bandage contact lens and the lack of prophylactic antibiotics may have been the source of bacterial keratitis.     

Origin of HIV-1 in the chimpanzee Pan troglodytes troglodytes

The human AIDS viruses human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) represent cross-species (zoonotic) infections. Although the primate reservoir of HIV-2 has been clearly identified as the sooty mangabey (Cercocebus atys), the origin of HIV-1 remains uncertain. Viruses related to HIV-1 have been isolated from the common chimpanzee (Pan troglodytes), but only three such SIVcpz infections have been documented, one of which involved a virus so divergent that it might represent a different primate lentiviral lineage. In a search for the HIV-1 reservoir, we have now sequenced the genome of a new SIVcpzstrain (SIVcpzUS) and have determined, by mitochondrial DNA analysis, the subspecies identity of all known SIVcpz-infected chimpanzees. We find that two chimpanzee subspecies in Africa, the central P. t. troglodytes and the eastern P. t. schweinfurthii, harbour SIVcpz and that their respective viruses form two highly divergent (but subspecies-specific) phylogenetic lineages. All HIV-1 strains known to infect man, including HIV-1 groups M, N and O, are closely related to just one of these SIVcpz lineages, that found in P. t. troglodytes. Moreover, we find that HIV-1 group N is a mosaic of SIVcpzUS- and HIV-1-related sequences, indicating an ancestral recombination event in a chimpanzee host. These results, together with the observation that the natural range of P. t. troglodytes coincides uniquely with areas of HIV-1 group M, N and O endemicity, indicate that P. t. troglodytes is the primary reservoir for HIV-1 and has been the source of at least three independent introductions of SIVcpz into the human population.     

Mild hypothermia as a protective therapy during intracranial aneurysm surgery: a randomized prospective pilot trial

OBJECTIVE: To conduct a pilot trial of mild intraoperative hypothermia during cerebral aneurysm surgery. METHODS: One hundred fourteen patients undergoing cerebral aneurysm clipping with (n = 52) (World Federation of Neurological Surgeons score < or =III) and without (n = 62) acute aneurysmal subarachnoid hemorrhage (SAH) were randomized to normothermic (target esophageal temperature at clip application of 36.5 degrees C) and hypothermic (target temperature of 33.5 degrees C) groups. Neurological status was prospectively evaluated before surgery, 24 and 72 hours postoperatively (National Institutes of Health Stroke Scale), and 3 to 6 months after surgery (Glasgow Outcome Scale). Secondary outcomes included postoperative critical care requirements, respiratory and cardiovascular complications, duration of hospitalization, and discharge disposition. RESULTS: Seven hypothermic patients (12%) could not be cooled to within 1 degrees C of target temperature; three of the seven were obese. Patients randomized to the hypothermic group more frequently required intubation and rewarming for the first 2 hours after surgery. Although not achieving statistical significance, patients with SAH randomized to the hypothermic group, when compared with patients in the normothermic group, had the following: 1) a lower frequency of neurological deterioration at 24 and 72 hours after surgery (21 versus 37-41%), 2) a greater frequency of discharge to home (75 versus 57%), and 3) a greater incidence of good long-term outcomes (71 versus 57%). For patients without acute SAH, there were no outcome differences between the temperature groups. There was no suggestion that hypothermia was associated with excess morbidity or mortality. CONCLUSION: Mild hypothermia during cerebral aneurysm surgery is feasible in nonobese patients and is well tolerated. Our results indicate that a multicenter trial enrolling 300 to 900 patients with acute aneurysmal SAH will be required to demonstrate a statistically significant benefit with mild intraoperative hypothermia.     

Dynamics of tremor-related oscillations in the human globus pallidus: a single case study

Physiological evidence indicates that the resting tremor of Parkinson's disease originates in oscillatory neural activity in the forebrain, but it is unknown whether that activity is globally synchronized or consists of parallel, independently oscillating circuits. In the present study, we used dual microelectrodes to record tremor-related neuronal activity from eight sites in the internal segment of the globus pallidus (GPi) from an awake Parkinson's disease patient undergoing stereotaxic pallidotomy. We utilized spectral analysis to evaluate the temporal correlations between multiunit activity at spatially separated sites and between neural and limb electromyographic activity. We observed that some GPi neural pairs oscillated synchronously at the tremor frequency, whereas other neural pairs oscillated independently. Additionally, we found that GPi tremor-related activity at a given site could fluctuate between states of synchronization and independence with respect to upper limb tremor. Consistent with this finding, some paired recording sites within GPi showed periods of transient synchronization. These observations support the hypothesis of independent tremor-generating circuits whose coupling can fluctuate over time.     

Age-related differences in management of heart disease: a study of cardiac medication use in an older cohort. Pacemaker Selection in the Elderly (PASE) Investigators

Bone mass, bone metabolic markers, and calcium regulation hormones were measured in members of an Antarctic wintering team who stayed at the Japanese Antarctic station, Syowa (latitude: south 69 degrees 00', longitude: east 39 degrees 35') for 1 year. Subjects included 31 healthy Japanese males, aged 24-51 years (mean age 34.5 years) at the beginning of this study, ingesting 488 IU/day of vitamin D and 550.9 mg/day of calcium per person. The long-term coefficient of variation (CV) of the equipment used in the assessments of bone mass was 0.67% in single X-ray absorptiometry (SXA), 0.17% in the speed of sound (SOS) by quantitative ultrasound method (QUS), and 0.63% in broadband ultrasound attenuation (BUA) by QUS. The seasonal changes in the calcaneal bone mineral density (BMD) by SXA were not significant, whereas the SOS measured by QUS decreased during the measurement period (0.55%, p < 0.001), and BUA increased (1.9%, p < 0.01). Bone-specific alkaline phosphatase and osteocalcin levels increased significantly during summer (p < 0.001) and urinary calcium level decreased significantly during winter (p < 0.05). Urinary pyridinoline and deoxypyridinoline levels decreased significantly at the end of winter (p < 0.001). Serum 1,25(OH)2D3 level did not change significantly, whereas serum 25(OH)D3 level decreased significantly during winter (p < 0.001). Serum parathyroid hormone (PTH) level significantly increased at the end of winter (p < 0.01), although both PTH level and 25(OH)D3 level remained within the normal range. We concluded that the 25(OH)D3 level in subjects who stayed in Antarctica for 1 year decreased significantly with the reduction in duration of sunshine, but there were no clear changes in bone mass.     

Molecular modelling of the ORL1 receptor and its complex with nociceptin

The opioid receptor like (ORL1) receptor is a G-protein coupled receptor superfamily, and regulates a plethora of neurophysiological functions. The structural requirements for receptor activation by its endogenous agonist, nociceptin (FGGFTGARKSARKLANQ), differ markedly from those of the kappa-opioid receptor and its putative peptide agonist, dynorphin A (YGGFLRRIRPKLKWDNQ). In order to probe the functional architecture of the ORL1 receptor, a molecular model of the receptor has been built, including the TM domain and the extra- and intracellular loops. An extended binding site able to accommodate nociceptin-(1-13), the shortest fully active analogue of nociceptin, has been characterized. The N-terminal FGGF tetrapeptide is proposed to bind in a highly conserved region, comprising two distinct hydrophobic pockets in a cavity formed by TM helices 3, 5, 6 and 7, capped by the acidic second extracellular (EL2) loop controlling access to the TM elements of the peptide binding site. The nociceptin conformation provides for the selective preference of the ORL1 receptor for nociceptin over dynorphin A, conferred by residue positions 5 and 6 (TG versus LR), and the favourable interaction of its highly positively charged core (residues 8-13) with the EL2 loop, thought to mediate receptor activation. The functional roles of the EL2 loop and the conserved N-terminal tetrapeptide opioid 'message' binding site are discussed in the context of the different structural requirements of the ORL1 and kappa-opioid receptors for activation.      

Tribological behavior and wear mechanisms of TiN/TiCN/TiN multilayer coatings

This work employs the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN⇔⇔N, and sequenced TiN⇔CN⇔N multilayer coatings with variable individual TiN-layer and TiCN-layer thicknesses on tungsten carbide disks and inserts. Also investigated are the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk, line-contact wear mode and ball-on-disk, point-contact wear mode through SRV reciprocating wear tests. Actual milling tests identify wear performance. Experimental results indicate that the coating with a total thickness of 7 Μm and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. No-tably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.