Photoinduced hole transfer in QD-phthalocyanine hybrids.

A series of CdSe quantum dot (QD)-phthalocyanine (Pc) hybrids were synthesized and their photophysics was studied using steady state and time-resolved spectroscopic methods. Emission of QDs was progressively quenched upon increasing the concentration of Pc in the hybrids. A detailed transient absorption study of the hybrids revealed that the mechanism of quenching is charge separation, resulting in the formation of hybrids with negatively charged QDs and the Pc cation. Direct photo-excitation of Pc did not show any detectable interaction between the excited state of Pc and the QD to which it is attached. An explanation is proposed, based on the suggestion that the energy of the lowest unoccupied molecular orbital (LUMO) of Pc is lower than the lower edge of the QD conduction band, while the energy of the highest occupied molecular orbital (HOMO) of Pc is sufficiently higher than the high energy edge of the QD valence band (VB), thus permitting hole transfer from the QD VB to the Pc HOMO after photo-excitation of QDs.

Dietary interventions for multiple sclerosis.

BACKGROUND: Clinical and experimental data suggest that certain dietary regimens, particularly those including polyunsaturated fatty acids (PUFAs) and vitamins might improve outcomes in people with multiple sclerosis (MS). Diets and dietary supplements are much used by people with MS in the belief that they might improve disease outcomes. OBJECTIVES: We performed a Cochrane review of all randomised trials of dietary regimens for MS with the aim of answering MS consumers' questions regarding the efficacy and safety of these interventions. SEARCH STRATEGY: We searched the Cochrane MS Group trial register (February 2006), Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 1, 2006, MEDLINE (PubMed) (1966 to March 2006), EMBASE (1974 to March 2006) and the bibliographies of papers found. SELECTION CRITERIA: All randomised controlled trials comparing a specific dietary intervention, diet plan or dietary supplementation, with no dietary modification or placebo, were eligible. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected articles, assessed trial quality and extracted data. Trial quality was poor, particularly as regards descriptions of randomisation, blinding and adverse event reporting. Some studies had large numbers of drop-outs; dropouts were never included in the analyses. MAIN RESULTS: PUFAs did not have a significant effect on disease progression, measured as worsening of Disability Status Scale. Omega-6 fatty acids (11-23 g/day linoleic acid) had no benefit in 75 relapsing remitting (RR) MS patients (progression at two years: relative risk (RR)=0.78, 95% CI [0.45 to 1.36]) or in 69 chronic progressive (CP) MS patients (RR=1.67, 95% CI [0.75 to 3.72]. Linoleic acid (2.9-3.4 g/day) had no benefit in CPMS (progression at two years: RR=0.78, 95% CI [0.43 to 1.42]). Slight decreases in relapse rate and relapse severity were associated with omega-6 fatty acids in some small studies, however these findings are limited by the limited validity of the endpoints.Omega-3 fatty acids had no benefit on progression at 12 months in 14 RRMS patients or at 24 months in 292 RRMS patients (RR=0.15, 95% CI [0.01 to 3.11], p= 0.22 at 12 months, and 0.82 95% CI [0.65 to 1.03], p=0.08, at 24 months). The low frequency of reported adverse events suggests no major toxicity associated with PUFA administration. No studies on vitamin supplementation and allergen-free diets were analysed as none met the eligibility criteria. AUTHORS' CONCLUSIONS: PUFAs seem to have no major effect on the main clinical outcome in MS (disease progression), and does not substantially affect the risk of clinical relapses over 2 years. However, the data available are insufficient to assess any potential benefit or harm from PUFA supplementation. Evidence bearing on the possible benefits and risks of vitamin supplementation and antioxidant supplements in MS is lacking. More research is required to assess the effectiveness of diets interventions in MS.

Structural and functional insights into the AmtB/Mep/Rh protein family.

X-ray crystallography revealed a similar architecture of the ammonium transport protein AmtB from Escherichia coli and the homologous protein Amt-1 from Archaeoglobus fulgidus. Furthermore, the atomic structures suggest that the proteins conduct ammonia (NH3) rather than ammonium ions (NH4+). These findings indicate that the more than 350 members of the ammonium transporter/methylamine permease/Rhesus (Amt/Mep/Rh) protein family found in archaea, bacteria, fungi, plants and animals are ammonia-conducting channels rather than ammonium ion transporters. The essential part of these proteins is the narrow hydrophobic ammonia-conducting pore with two highly conserved histidine residues located in the middle of the pore. A specific ammonium ion binding site is found at the extracellular entry site of E. coli AmtB. E. coli AmtB and its regulator GlnK form an effective ammonium sensory system that couples intracellular gene regulation by the nitrogen control system to external changes in ammonium availability. Based on structural and functional analysis of various mutants, two conserved histidine residues were found to be essential for substrate conductance also in the functional eukaryotic ammonium transporters. The next big challenge in the field surely is to determine the atomic structure of Rh proteins.

Presence of human immunodeficiency virus (HIV) type 1 subtype A infection in a New York community with high HIV prevalence: a sentinel site for monitoring HIV genetic diversity in North America. Centers for Disease Control and Prevention-Bronx Lebanon HIV Serosurvey Team.

To determine whether US residents are infected with subtypes of human immunodeficiency virus (HIV) type 1 other than subtype B (Western), the predominant North American subtype with a unique GPGR genetic sequence in the V3 loop, viruses from 22 HIV-infected adults were serotyped and subtyped. Twenty patients had subtype B (Western), of whom 15 had serotype B (Western), 3 had serotype A/C, 1 had serotype B (Thai), and 1 had a nontypeable serotype. Two had subtype A, both serotype A/C. Both subtype A-infected patients, only 1 of whom had been outside the United States, reported sex with persons traveling abroad, suggesting possible acquisition in the United States. Because US residents are infected with non-subtype B (Western) strains, US surveillance for HIV-1 diversity is needed to elucidate subtype-specific transmission patterns and pathogenesis and to guide evaluation and development of HIV diagnostic tests and vaccines.

[Peripheral neuropathy during ocular myopathy: description of a case]. / Neuropatia periferica in corso di miopatia oculare: descrizione di un caso.

A case of ocular myopathy view presents only slight subjective symptoms, but a wide range of objective manifestations. The clinical features, but above all the morphological aspects of the muscle and the peripheral nerve presented by the patient, are briefly discussed, also in view of possible pathogenetic correlations.

Biological safety cabinets, decontamination or sterilization with paraformaldehyde.

Bacillus subtilis var. niger spores were used to determine the exposure time for formaldehyde decontamination of biological safety cabinets. Formaldehyde contact times less than 3 hr were insufficient for sterilization. A contact time of 4 hr or more resulted in a reproducible killing of the spore strips placed inside the cabinets. At 6 hr sufficient formaldehyde had diffused through the high efficiency particulate air (HEPA) filter to sterilize the strips with lower spore counts. A minimum of 5 to 6 logs of killing were observed after 4 to 6 hr of treatment.

Changes in Endoglucanase Patterns during Growth of Thermomonospora curvata on Cellulose.

The endoglucanases of the thermophilic actinomycete Thermomonospora curvata were characterized. Early-exponential-phase culture fluid contained at least three endoglucanases, with molecular weights of 23,000, 46,000, and 146,000 and K(m) values of 1.54, 3.60, and 1.32% carboxymethyl cellulose, respectively. The stationary-phase pattern was altered to include three enzymes with molecular weights of 52,000, 114,000, and 106,000, with respective K(m) values of 1.77, 8.30, and 1.91%.

The cytoskeleton of murine leukemia virus (MuLV)-infected mouse fibroblasts as observed under varying conditions of formaldehyde fixation.

Mouse fibroblasts chronically infected with Moloney murine leukemia virus (MuLV) were fixed using variable amounts of formaldehyde, then examined by indirect immunofluorescence light microscopy. Several antisera were employed to detect both external and internal antigens associated with the cells, eg, MuLV gp70, tubulin, vimentin, and actin. Our results indicate that the cell membranes could be partially permeabilized to IgG molecules directed against the three cytoskeletal antigens only after 3.7%, but not 1%, formaldehyde treatment. Complete permeabilization was achieved by subsequent acetone treatment of cells after 3.7% formaldehyde fixation. In such cells, normal-appearing cytoskeletal networks of microtubules and intermediate filaments were observed. Stress fibers were also seen; however, they appeared less numerous and thinner than those of uninfected mouse fibroblasts. Further, a significant amounts of F-actin fluorescence was localized in granules in the cytoplasm of infected cells. Similar observations were made using JLS-V9 mouse cells chronically infected with 334C virus, another MuLV. These results taken together suggest that subtle differences exist in the organization of actin within MuLV-infected and uninfected mouse fibroblasts.

Enhanced cellulase production in mutants of Thermomonospora curvata.

Thermomonospora curvata, a thermophilic actinomycete, secretes multiple forms of endo-beta 1-4-glucanase (EG)when grown on cellulose-mineral salts liquid medium. The EG activity(measured as carboxymethyl cellulose hydrolysis) was separated by ion exchange chromatography into three distinct components which differ in their kinetic properties. Exposure of Thm. curvata to ultraviolet light, N-nitrosoguanidine, or ethane methyl sulfonate produced mutants with enhanced EG production. Selection of colonies which cleared cellulose agar plant containing 2-deoxtglucose of glycerol yielded mutants having 1.5 to 2.6 times the extracellular EG and saccharifying activity (measured by filter-paper and cotton-fiber hydrolysis). The secretion of extracellular protein was increased proportionally in mutant cultures.