220 research outputs found
The Summer Standing Crop, Growth and Distribution of Chironomus plumosus, in Lake Itasca, Minnesota
During the period 15 June to 3 September 1965, 626 Ekman dredge hauls were made in Lake Itasca, Minnesota. The numbers and weights of Chironomus plumosus L. at 6 m, 7 m, 8 m, Siefert\u27s Hole (9.5 - l 0.4 m), and Peace Pipe Vista (11.5 - 13.7 m) depression were determined. In addition, the numbers and weights of several other benthic dipteran larvae, Cryptochironomus, Palpomyia, and Procladius, normal associates of C. plumosus, were determined. A loss of 98,407 larvae/ha/day occurred in the 6-9 m stratum during the 12 weeks. There was a decrease in numbers of larvae of 79.3% and 84% at Siefert\u27s Hole and Peace Pipe Vista depression, respectively. The summer decrease in biomass was 4.23 kg/ha/day in the 6-9 m stratum, 1.72 kg/ha/day in Siefert\u27s Hole, and 0.98 kg/ha/day in the Peace Pipe Vista depression. The individual larvae were gaining weight during the 12 week period when the biomass was decreasing. The ANOVA of numbers of larvae during the last seven weeks of the sampling period showed significant effects of depth and time on numbers, but no significant interaction. Fisher\u27s coefficient of dispersion was used to determine the distributional patterns of larvae al the various sampling depths; few collections varied significantly from random distribution, in several samples from Siefert\u27s Hole and the Peace Pipe Vista depression the larvae showed a clumped distribution. The number of larvae surviving to 3 September were estimated to represent a potential pupal crop of 87.31 kg/ha in the 6-10.5 m stratum
IMMUNOPATHOGENESIS OF ACUTE CENTRAL NERVOUS SYSTEM DISEASE PRODUCED BY LYMPHOCYTIC CHORIOMENINGITIS VIRUS : II. ADOPTIVE IMMUNIZATION OF VIRUS CARRIERS
Lymphocytic choriomeningitis (LCM) virus carriers were established by intracerebral inoculation of adult BALB/c mice followed by a single dose of cyclophosphamide (CY) (150 mg/kg) 3 days after infection, and by intracerebral injection within 24 hr of birth. These carriers were then adoptively immunized with spleen cells or serum from immune or normal BALB/c donors. Transfer of immune spleen cells into drug-induced carriers consistently resulted in acutely fatal choriomeningitis, histologically strikingly similar to classical LCM. Normal spleen cells or immune serum failed to produce either central nervous system (CNS) pathology or illness with any regularity. In addition, focal necrosis of the cerebellum was seen after adoptive immunization of drug-induced carriers but only when mice received cells at least 3 wk after inoculation, which is probably explained by the gradual spread of infection from membranes to the neural parenchyma during the first month after establishment of the carrier state in adult mice. Immune spleen cells, when transferred to neonatal carriers, led to a decrease in virus titers in blood and brains and to development of antibody without acute CNS disease. It appears that the production of fatal choriomeningitis after LCM infection is determined in part by the distribution of viral antigen, and this is markedly different in neonatal and drug-induced carriers at the time of cell transfer. Another factor of potential importance is the much higher level of circulating viral antigen in the plasma of neonatal than in that of drug-induced LCM carriers. Classical LCM disease can only be transferred by immune lymphoid cells and not by antiserum. Furthermore, little or no complement-fixing (CF) antibody was found in the plasma of mice dying of acute choroiditis. These observations strongly suggest that acute choroiditis is dependent upon the cell-mediated immune response
IMMUNOPATHOGENESIS OF ACUTE CENTRAL NERVOUS SYSTEM DISEASE PRODUCED BY LYMPHOCYTIC CHORIOMENINGITIS VIRUS : I. CYCLOPHOSPHAMIDE-MEDIATED INDUCTION OF THE VIRUS-CARRIER STATE IN ADULT MICE
A single dose of 150 mg/g of cyclophosphamide (CY), given 3 days after intracerebral (i.c.) inoculation of lymphocytic choriomeningitis (LCM) virus, protected over 90% of adult BALB/c mice against acutely fatal choriomeningitis. Surviving mice became persistently infected carriers, with high virus titers in blood and brain. Immunofluorescent examination of the brain showed that in CY-induced carriers infection was initially confined to the choroid plexus, ependyma, and leptomeninges, but over the next 30 days gradually spread to the neural parenchyma, most notably to the molecular layer of the cerebellum. By contrast, LCM virus-carrier mice produced by neonatal virus injection and examined as adults, showed a much less marked infection of choroid plexus and much more widespread infection of parenchyma, with a different distribution among brain nuclei, including heavy infection of the Purkinje cells of the cerebellum
Effect of 2\u27,3\u27-Didehydro-3\u27-Deoxythymidine in an In Vitro Hollow-Fiber Pharmacodynamic Model System Correlates with Results of Dose-Ranging Clinical Studies
We sought to validate an in vitro system which could predict the minimal effect dose of antiretroviral agents. Mixtures of uninfected CEM cells and CEM cells chronically infected with human immunodeficiency virus (HIV) type 1 MN were exposed to 2\u27,3\u27-didehydro-3\u27-deoxythymidine (D4T) in vitro in a hollow-fiber model which simulates the plasma concentration-time profile of D4T in patients. Drug concentration was adjusted to simulate continuous intravenous infusion, or an intravenous bolus administered twice daily. The effect of the dosing regimen was measured with viral infectivity, p24 antigen, and reverse transcriptase or PCR for unintegrated HIV DNA. Dose deescalation studies on a twice-daily dosing schedule predicted a minimum effect dose of 0.5 mg/kg of body weight per day which correlated with the results of a clinical trial. Antiviral effect was demonstrated to be independent of schedule for every 12-h dosing versus continuous infusion. Finally, at or near the minimal effect dose, efficacy appeared to depend on the viral load. The ability of this in vitro pharmacodynamic model to assess the response of HIV-infected cells to different doses and schedules of antiviral agents may be useful in the design of optimal dosing regimens for clinical trials but requires validation with other types of antiretroviral agents
Recommended from our members
Review and assessment of smartphone apps for forest restoration monitoring
With increased interest in forest restoration comes an urgent need to provide accurate, scalable, and cost‐effective monitoring tools. The ubiquity of smartphones has led to a surge in monitoring apps. We reviewed and assessed monitoring apps found through web searches and conversations with practitioners. We identified 42 apps that (1) automatically monitor indicators or (2) facilitate data entry. We selected the five most promising from the first category, based on their relevance, availability, stability, and user support. We compared them to traditional field techniques in a well‐studied restoration project in Costa Rica. We received further feedback from 15 collaborator organizations that evaluated these in their corresponding field restoration sites. Diameter measurements correlated well with traditional tape‐based measurements (R2 = 0.86–0.89). Canopy openness and ground cover showed weaker correlations to densiometer and quadrat cover measurements (R2 = 0.42–0.51). Apps did not improve labor efficiency but do preclude the purchase of specialized field equipment. The apps reviewed here need further development and validation to support monitoring adequately, especially in the tropics. Estimates of development and maintenance costs, as well as statistics on user uptake, are required for cost‐effective development. We recommend a coordinated effort to develop dedicated restoration monitoring apps that can speed up and standardize the collection of indicators and provide evidence on restoration outcomes alongside a centralized repository of this information
Alcohol Consumption Trajectory Patterns in Adult Women with HIV Infection
HIV-infected women with excessive alcohol consumption are at risk for adverse health outcomes, but little is known about their long-term drinking trajectories. This analysis included longitudinal data, obtained from 1996–2006, from 2791 women with HIV from the Women’s Interagency HIV Study. Among these women, the proportion in each of five distinct drinking trajectories was: continued heavy drinking (3%), reduction from heavy to non-heavy drinking (4%), increase from non-heavy to heavy drinking (8%), continued non-heavy drinking (36%), and continued non-drinking (49%). Depressive symptoms, other substance use (crack/cocaine, marijuana, and tobacco), co-infection with HCV, and heavy drinking prior to enrollment were associated with trajectories involving future heavy drinking. In conclusion, many women with HIV change their drinking patterns over time. Clinicians and those providing alcohol-related interventions might target those with depression, current use of tobacco or illicit drugs, HCV infection, or a previous history of drinking problems
The White Mountain Polarimeter Telescope and an Upper Limit on CMB Polarization
The White Mountain Polarimeter (WMPol) is a dedicated ground-based microwave
telescope and receiver system for observing polarization of the Cosmic
Microwave Background. WMPol is located at an altitude of 3880 meters on a
plateau in the White Mountains of Eastern California, USA, at the Barcroft
Facility of the University of California White Mountain Research Station.
Presented here is a description of the instrument and the data collected during
April through October 2004. We set an upper limit on -mode polarization of
14 (95% confidence limit) in the multipole range
. This result was obtained with 422 hours of observations of a 3
sky area about the North Celestial Pole, using a 42 GHz
polarimeter. This upper limit is consistent with polarization predicted
from a standard -CDM concordance model.Comment: 35 pages. 12 figures. To appear in ApJ
SUPPA2:fast, accurate, and uncertainty-aware differential splicing analysis across multiple conditions
Supplementary methods. (PDF 315 kb
Cortical Mechanics and Meiosis II Completion in Mammalian Oocytes Are Mediated by Myosin-II and Ezrin-Radixin-Moesin (ERM) Proteins
Analysis of mouse oocyte mechanics shows that effective tension drops 6-fold from prophase I to metaphase II; the metaphase II egg has a 2.5-fold tension differential between the cortex over the spindle and the opposite cortex. Manipulation of actin, myosin-II, or ERMs alters tension levels and induces spindle abnormalities during meiosis II
- …