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1.
Nature ; 519(7543): 339-43, 2015 Mar 19.
Article in English | MEDLINE | ID: mdl-25731165

ABSTRACT

The climatic impact of CO2 and other greenhouse gases is usually quantified in terms of radiative forcing, calculated as the difference between estimates of the Earth's radiation field from pre-industrial and present-day concentrations of these gases. Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annual-mean radiative forcing at the tropopause of 1.82Ā Ā±Ā 0.19Ā WĀ m(-2) (ref. 2). However, despite widespread scientific discussion and modelling of the climate impacts of well-mixed greenhouse gases, there is little direct observational evidence of the radiative impact of increasing atmospheric CO2. Here we present observationally based evidence of clear-sky CO2 surface radiative forcing that is directly attributable to the increase, between 2000 and 2010, of 22 parts per million atmospheric CO2. The time series of this forcing at the two locations-the Southern Great Plains and the North Slope of Alaska-are derived from Atmospheric Emitted Radiance Interferometer spectra together with ancillary measurements and thoroughly corroborated radiative transfer calculations. The time series both show statistically significant trends of 0.2Ā WĀ m(-2) per decade (with respective uncertainties of Ā±0.06Ā WĀ m(-2) per decade and Ā±0.07Ā WĀ m(-2) per decade) and have seasonal ranges of 0.1-0.2Ā WĀ m(-2). This is approximately ten per cent of the trend in downwelling longwave radiation. These results confirm theoretical predictions of the atmospheric greenhouse effect due to anthropogenic emissions, and provide empirical evidence of how rising CO2 levels, mediated by temporal variations due to photosynthesis and respiration, are affecting the surface energy balance.


Subject(s)
Carbon Dioxide , Infrared Rays , Observation , Alaska , Atmosphere/chemistry , Carbon Dioxide/analysis , Cell Respiration , Greenhouse Effect/statistics & numerical data , Models, Theoretical , Photosynthesis , Seasons , Time Factors
2.
Faraday Discuss ; 200: 429-451, 2017 08 24.
Article in English | MEDLINE | ID: mdl-28581559

ABSTRACT

Methane emissions contribute to global warming, damage public health and reduce the yield of agricultural and forest ecosystems. Quantifying these damages to the planetary commons by calculating the social cost of methane (SCM) facilitates more comprehensive cost-benefit analyses of methane emissions control measures and is the first step to potentially incorporating them into the marketplace. Use of a broad measure of social welfare is also an attractive alternative or supplement to emission metrics focused on a temperature target in a given year as it incentivizes action to provide benefits over a broader range of impacts and timescales. Calculating the SCM using consistent temporal treatment of physical and economic processes and incorporating climate- and air quality-related impacts, we find large SCM values, e.g. Ć¢ĀˆĀ¼$2400 per ton and Ć¢ĀˆĀ¼$3600 per ton with 5% and 3% discount rates respectively. These values are Ć¢ĀˆĀ¼100 and 50 times greater than corresponding social costs for carbon dioxide. Our results suggest that Ć¢ĀˆĀ¼110 of 140 Mt of identified methane abatement via scaling up existing technology and policy options provide societal benefits that outweigh implementation costs. Within the energy sector, renewables compare far better against use of natural gas in electricity generation when incorporating these social costs for methane. In the agricultural sector, changes in livestock management practices, promoting healthy diets including reduced beef and dairy consumption, and reductions in food waste have been promoted as ways to mitigate emissions, and these are shown here to indeed have the potential to provide large societal benefits (Ć¢ĀˆĀ¼$50-150 billion per year). Examining recent trends in methane and carbon dioxide, we find that increases in methane emissions may have offset much of the societal benefits from a slowdown in the growth rate of carbon dioxide emissions. The results indicate that efforts to reduce methane emissions via policies spanning a wide range of technical, regulatory and behavioural options provide benefits at little or negative net cost. Recognition of the full SCM, which has typically been undervalued, may help catalyze actions to reduce emissions and thereby provide a broad set of societal benefits.


Subject(s)
Methane/economics
3.
Psychol Sci ; 26(3): 348-53, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25576344

ABSTRACT

In this study, we drew on prospective, longitudinal data to investigate the long-term predictive significance of the quality of early parent-child relationship experiences for adults' sympathetic nervous system (SNS) activity during conflict discussions with their romantic partners. Maternal sensitivity was repeatedly assessed across childhood via direct observations of mother-child interactions. When the children in the study became adults (34-37 years old), electrodermal activity-an index of SNS arousal and a psychophysiological marker of behavioral inhibition-was recorded for 37 participants while at rest and while they attempted to resolve conflicts in their romantic relationships. Individuals who had experienced less sensitive maternal caregiving during childhood had greater increases in electrodermal activity during conflict discussions with their adult partners, relative to resting conditions. This longitudinal association was not accounted for by observed or self-reported romantic-relationship quality, gender, ethnicity, or early socioeconomic factors.


Subject(s)
Family Conflict/psychology , Galvanic Skin Response/physiology , Mother-Child Relations/psychology , Adult , Female , Humans , Interpersonal Relations , Longitudinal Studies , Male , Prospective Studies
4.
Mult Scler ; 20(4): 471-80, 2014 Apr.
Article in English | MEDLINE | ID: mdl-23950550

ABSTRACT

BACKGROUND: Reduction in peripheral blood lymphocytes is an expected pharmacodynamic outcome of fingolimod therapy. OBJECTIVE: The objective of this article is to evaluate lymphocyte dynamics during and after fingolimod therapy and assess the relationship between lymphocyte counts and infections. METHODS: Lymphocyte counts and their relationship with infections were evaluated in three multiple sclerosis (MS) populations: (Group A) FREEDOMS phase 3 core study group (n = 1272); (Group B) All Studies group (one phase 2 and two phase 3 studies, plus their extensions; n = 2315); and (Group C) Follow-up group (after fingolimod discontinuation; n = 538). RESULTS: Administration of fingolimod 0.5 mg led to reductions in lymphocyte counts to a steady-state of 24%-30% of baseline values within two weeks, which remained stable while on therapy. Following fingolimod discontinuation, average counts exceeded the lower limit of normal range within six to eight weeks, and were 80% of baseline values by three months. In Group A, infection rates per patient-year were 1.4 with placebo and 1.0 in fingolimod-treated patients who had the lowest lymphocyte counts (< 0.2 Ɨ 10(9)/l). No evidence was seen for an increase in serious or opportunistic infections. CONCLUSIONS: Fingolimod induces a rapid and reversible reduction in lymphocyte counts without an increase in infections relative to placebo. Because fingolimod reduces blood lymphocyte counts via redistribution in secondary lymphoid organs, peripheral blood lymphocyte counts cannot be utilized to evaluate the lymphocyte subset status of a patient.


Subject(s)
Immunosuppressive Agents/therapeutic use , Infections/epidemiology , Lymphocytes/drug effects , Multiple Sclerosis/drug therapy , Multiple Sclerosis/immunology , Propylene Glycols/therapeutic use , Sphingosine/analogs & derivatives , Adolescent , Adult , Female , Fingolimod Hydrochloride , Humans , Lymphocyte Count , Male , Middle Aged , Sphingosine/therapeutic use , Young Adult
5.
J Child Psychol Psychiatry ; 54(11): 1223-30, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23731038

ABSTRACT

BACKGROUND: Longitudinal research has demonstrated that individual differences in attachment security show only modest continuity from infancy to adulthood. Recent findings based on retrospective reports suggest that individuals' genetic variation may moderate the developmental associations between early attachment-relevant relationship experiences and adult attachment security. The purpose of this study was to use a prospective, longitudinal design to investigate genetic contributions to continuity and changes in attachment security from infancy to young adulthood in a higher risk sample. METHODS: Infant attachment security was assessed using the Strange Situation Procedure at 12 and 18 months. Adults' general attachment representations were assessed using the Adult Attachment Interview at ages 19 and 26. Romantic attachment representations were assessed with the Current Relationship Interview (CRI) at ages 20-21 and ages 26-28. Individuals were genotyped for variants within the oxytocin receptor (OXTR), dopamine D4 receptor (DRD4), and serotonin transporter linked polymorphic region (5-HTTLPR). RESULTS: The continuity of attachment security from infancy into young adulthood was consistently moderated by OXTR genetic variation. Infant attachment security predicted the security of adults' general and romantic attachment representations only for individuals with the OXTR G/G genotype. This interaction was significant when predicting adult attachment security as measured by the Adult Attachment Interview at ages 19 and 26 and the CRI at ages 26-28. Dopamine D4 receptor and 5-HTTLPR genetic variation did not consistently moderate the longitudinal associations between attachment security during infancy and adulthood. CONCLUSIONS: This study provides initial longitudinal evidence for genetic contributions to continuity and change in attachment security from infancy to young adulthood. Genetic variation related to the oxytocin system may moderate the stability of attachment security across development.


Subject(s)
Human Development/physiology , Interpersonal Relations , Mother-Child Relations/psychology , Object Attachment , Receptors, Oxytocin/genetics , Adult , Female , Genetic Variation , Genotype , Humans , Infant , Male , Polymorphism, Genetic/genetics , Prospective Studies , Receptors, Dopamine D4/genetics , Risk , Serotonin Plasma Membrane Transport Proteins/genetics , Young Adult
6.
Nature ; 448(7155): 791-4, 2007 Aug 16.
Article in English | MEDLINE | ID: mdl-17653194

ABSTRACT

The evolution of the Earth's climate over the twenty-first century depends on the rate at which anthropogenic carbon dioxide emissions are removed from the atmosphere by the ocean and land carbon cycles. Coupled climate-carbon cycle models suggest that global warming will act to limit the land-carbon sink, but these first generation models neglected the impacts of changing atmospheric chemistry. Emissions associated with fossil fuel and biomass burning have acted to approximately double the global mean tropospheric ozone concentration, and further increases are expected over the twenty-first century. Tropospheric ozone is known to damage plants, reducing plant primary productivity and crop yields, yet increasing atmospheric carbon dioxide concentrations are thought to stimulate plant primary productivity. Increased carbon dioxide and ozone levels can both lead to stomatal closure, which reduces the uptake of either gas, and in turn limits the damaging effect of ozone and the carbon dioxide fertilization of photosynthesis. Here we estimate the impact of projected changes in ozone levels on the land-carbon sink, using a global land carbon cycle model modified to include the effect of ozone deposition on photosynthesis and to account for interactions between ozone and carbon dioxide through stomatal closure. For a range of sensitivity parameters based on manipulative field experiments, we find a significant suppression of the global land-carbon sink as increases in ozone concentrations affect plant productivity. In consequence, more carbon dioxide accumulates in the atmosphere. We suggest that the resulting indirect radiative forcing by ozone effects on plants could contribute more to global warming than the direct radiative forcing due to tropospheric ozone increases.


Subject(s)
Carbon/metabolism , Ecosystem , Greenhouse Effect , Ozone/pharmacology , Plants/drug effects , Atmosphere/chemistry , Carbon Dioxide/analysis , Carbon Dioxide/metabolism , Ozone/analysis , Ozone/toxicity , Photosynthesis/drug effects , Plant Development , Plant Epidermis/cytology , Plant Epidermis/drug effects , Plant Epidermis/metabolism , Plants/metabolism , Switzerland
7.
Dev Psychopathol ; 25(3): 843-56, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23880395

ABSTRACT

This study tests a model of young adult romantic quality as a moderator of the effects of early caregiving on anxious-depressed symptoms over a 9-year period in adulthood. Participants (n = 93) were a subsample from a longitudinal study of risk and adaptation. Quality of early caregiving was measured using observational data collected at five points in the first 4 years of life. Young adult romantic relationship quality was assessed from interviews with participants at age 23. Self-report anxious-depressed symptoms were measured at ages 23, 26, and 32. The results indicated that romantic quality moderated early caregiving to predict symptom levels across this period, with evidence for inoculation, amplification, and compensation effects. A discriminant analysis examining young adult work competence as a moderator provided further evidence for the distinctiveness of romantic relationships in changing the association between early caregiving and adult internalizing symptoms.


Subject(s)
Anxiety/psychology , Depression/psychology , Interpersonal Relations , Sexual Behavior/psychology , Sexual Partners/psychology , Adult , Female , Humans , Longitudinal Studies , Male
8.
Health Commun ; 28(1): 20-8, 2013.
Article in English | MEDLINE | ID: mdl-23330855

ABSTRACT

The Extended Parallel Process Model (EPPM) posits that an effective fear appeal includes both threat and efficacy components; however, research has not addressed whether there is an optimal threat-to-efficacy ratio. It is possible that varying levels of threat and efficacy in a persuasive message could yield different effects on attitudes, beliefs, and behaviors. In a laboratory experiment, women (n = 442) were exposed to human papilloma virus (HPV) prevention messages containing one of six threat-to-efficacy ratios and one of two message frames (messages emphasizing the connection between HPV and cervical cancer or HPV and genital warts). Multiple mediation analysis revealed that a 1-to-1 ratio of threat to efficacy was most effective at increasing prevention intentions, primarily because it caused more fear and risk susceptibility than other message ratios. Response efficacy significantly mediated the relationship between message framing and intentions, such that participants exposed to a genital warts message reported significantly higher intentions, and this association can be explained in part through response efficacy. Implications for future theoretical research as well as campaigns and intervention research are discussed.


Subject(s)
Fear , Models, Psychological , Papillomavirus Infections/prevention & control , Persuasive Communication , Self Efficacy , Adolescent , Adult , Female , Health Knowledge, Attitudes, Practice , Humans , Midwestern United States , Young Adult
9.
Child Dev ; 83(5): 1689-702, 2012.
Article in English | MEDLINE | ID: mdl-22694197

ABSTRACT

To test proposals regarding the hierarchical organization of adult attachment, this study examined developmental origins of generalized and romantic attachment representations and their concurrent associations with romantic functioning. Participants (N=112) in a 35-year prospective study completed the Adult Attachment Interview (AAI) and Current Relationship Interview (CRI). Two-way analysis of variance tested interactive associations of AAI and CRI security with infant attachment, early parenting quality, preschool ego resiliency, adolescent friendship quality, and adult romantic functioning. Both representations were associated with earlier parenting and core attachment-related romantic behavior, but romantic representations had distinctive links to ego resiliency and relationship-specific romantic behaviors. Attachment representations were independent and did not interactively predict romantic functioning, suggesting that they confer somewhat distinctive benefits for romantic functioning.


Subject(s)
Courtship/psychology , Object Attachment , Parent-Child Relations , Resilience, Psychological , Adolescent , Adult , Analysis of Variance , Ego , Family Characteristics , Female , Friends , Humans , Interpersonal Relations , Male , Personal Satisfaction , Prospective Studies , Young Adult
10.
Affect Sci ; 3(3): 577-602, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36185503

ABSTRACT

The COVID-19 pandemic (and its aftermath) highlights a critical need to communicate health information effectively to the global public. Given that subtle differences in information framing can have meaningful effects on behavior, behavioral science research highlights a pressing question: Is it more effective to frame COVID-19 health messages in terms of potential losses (e.g., "If you do not practice these steps, you can endanger yourself and others") or potential gains (e.g., "If you practice these steps, you can protect yourself and others")? Collecting data in 48 languages from 15,929 participants in 84 countries, we experimentally tested the effects of message framing on COVID-19-related judgments, intentions, and feelings. Loss- (vs. gain-) framed messages increased self-reported anxiety among participants cross-nationally with little-to-no impact on policy attitudes, behavioral intentions, or information seeking relevant to pandemic risks. These results were consistent across 84 countries, three variations of the message framing wording, and 560 data processing and analytic choices. Thus, results provide an empirical answer to a global communication question and highlight the emotional toll of loss-framed messages. Critically, this work demonstrates the importance of considering unintended affective consequences when evaluating nudge-style interventions.

11.
Psychol Sci ; 22(3): 376-83, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21245491

ABSTRACT

This study adopted a developmental perspective on recovery from conflict in romantic relationships. Participants were 73 young adults (target participants), studied since birth, and their romantic partners. A novel observational coding scheme was used to evaluate each participant's degree of conflict recovery, operationalized as the extent to which the participant disengaged from conflict during a 4-min "cool-down" task immediately following a 10-min conflict discussion. Conflict recovery was systematically associated with developmental and dyadic processes. Targets who were rated as securely attached more times in infancy recovered from conflict better, as did their romantic partners. Concurrently, having a romantic partner who displayed better recovery predicted more positive relationship emotions and greater relationship satisfaction. Prospectively, target participants' early attachment security and their partners' degree of conflict recovery interacted to predict relationship stability 2 years later, such that having a partner who recovered from conflict better buffered targets with insecure histories.


Subject(s)
Love , Negotiating/psychology , Personality Development , Adaptation, Psychological , Emotions , Female , Follow-Up Studies , Humans , Individuality , Infant , Male , Object Attachment , Parent-Child Relations , Personal Satisfaction , Social Support , Transfer, Psychology , Young Adult
12.
Psychol Sci ; 22(7): 908-15, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21617252

ABSTRACT

We tested hypotheses concerning the developmental roots of becoming the "weak-link" (less committed) partner in adult romantic relationships and the associations between partners' absolute and relative levels of commitment and dyadic outcomes. We examined 78 target 20- to 21-year-olds who were involved in a romantic relationship and who had been studied since birth. As predicted, people who received lower-quality support from caregivers in toddlerhood or who were less able to resolve conflicts with a best friend in midadolescence were more likely to become the weak-link partner in a romantic relationship at age 20 to 21. Furthermore, lower commitment on the part of the weak-link partner coupled with greater discrepancy in commitment between partners predicted a greater likelihood that the couple would display hostility (rated by observers) during a videotaped conflict-resolution task when they were 20 to 21 years old. These findings are discussed from developmental and dyadic perspectives.


Subject(s)
Interpersonal Relations , Love , Female , Friends/psychology , Hostility , Humans , Male , Negotiating , Parenting/psychology , Personality Development , Young Adult
13.
Psychol Rep ; 124(3): 1268-1281, 2021 Jun.
Article in English | MEDLINE | ID: mdl-32515276

ABSTRACT

Inhibitory control is a key executive function and has been studied extensively using the stop signal task. By applying a simple race model that posits an independent race between a GO process responsible for initiation of responses and a STOP process responsible for inhibition of responses, one can estimate how long it takes an individual to inhibit an ongoing response, the stop signal reaction time. Here, we examined how stop signal reaction time can be affected by working memory. Participants engaged in a dual task; they completed a stop signal task under low and high working memory load conditions. Working memory capacity was also measured. We found that the STOP process was lengthened in the high, compared to the low, working memory load condition, as evidenced by differences in stop signal reaction time. The GO process was unaffected and working memory capacity could not account for differences across the load conditions. These results indicate that inhibitory control can be influenced by placing demands on working memory.


Subject(s)
Executive Function , Inhibition, Psychological , Memory, Short-Term , Reaction Time , Female , Humans , Male , Young Adult
14.
J Exp Med ; 156(1): 20-30, 1982 Jul 01.
Article in English | MEDLINE | ID: mdl-7045272

ABSTRACT

Monoclonal antibodies were raised against sporozoites of two species of malaria parasites, Plasmodium falciparum and Plasmodium vivax. The antibodies reacted with polypeptides (circumsporozoite proteins) that are uniformly distributed over the entire surface of sporozoites, as shown by indirect immunofluorescence and by the circumsporozoite precipitin reaction. The epitopes recognized by the monoclonal antibodies were expressed on sporozoites from different geographical isolates of the homologous species but were not detected on sporozoites of heterologous species nor on blood forms of the parasite. The monoclonal antibody to P. falciparum specifically immunoprecipitated two polypeptides of apparent 67,000 mol wt (Pf67) and 58,000 mol wt (Pf58) from extracts of [35S]methionine-labeled P. falciparum sporozoites. Similarly, the anti-P. vivax monoclonal immunoprecipitated two proteins of 51,000 mol wt (Pv51) and 45,000 mol wt (Pv45) from extracts of metabolically labeled P. vivax sporozoites. The extracts were also reacted with the serum of human volunteers successfully vaccinated with sporozoites of either P. vivax or P. falciparum. The patterns of immunoprecipitation were almost identical to those obtained with the corresponding monoclonal antibodies. The circumsporozoite proteins of P. falciparum and P. vivax play a role in immune protection. Incubation of the appropriate monoclonal antibody with viable sporozoites of the homologous species significantly reduced parasite infectivity, as determined by sporozoite neutralization assays carried out in splenectomized chimpanzees.


Subject(s)
Antigens/isolation & purification , Malaria/immunology , Animals , Antibodies, Monoclonal/biosynthesis , Antibodies, Monoclonal/isolation & purification , Antigen-Antibody Reactions , Chemical Precipitation , Humans , Malaria/parasitology , Mice , Neutralization Tests , Pan troglodytes , Peptides/isolation & purification , Plasmodium falciparum/immunology , Plasmodium falciparum/pathogenicity , Plasmodium vivax/immunology , Plasmodium vivax/pathogenicity , Species Specificity
15.
Science ; 161(3836): 56, 1968 Jul 05.
Article in English | MEDLINE | ID: mdl-4871793

ABSTRACT

Anopheles freeborni mosquitoes were infected by feeding on a New World monkey, Aotus trivirgatus, infected with the Malayan IV strain of Plasmodium falciparum. After a normal incubation period, the infection was passed to a human volunteer through the bites of these mosquitoes, demonstrating for the first time the practicability of using a simian host as a donor for the infection of mosquitoes with this species of human malarial parasites.


Subject(s)
Anopheles , Malaria , Monkey Diseases , Plasmodium falciparum , Zoonoses , Animals , Humans , Insect Bites and Stings , Insect Vectors
16.
Science ; 165(3896): 918-9, 1969 Aug 29.
Article in English | MEDLINE | ID: mdl-4978959

ABSTRACT

Anopheles freeborni mosquitoes were infected by feeding on New World monkeys, Aotus trivirgatus, infected with a Nigerian strain of Plasmodium malariae. The infection was passed to human volunteers through the bites of these mosquitoes, demonstrating the practicability of using a simian host for infection of mosquitoes with a third species of human malaria parasite and of the use of such mosquitoes to transmit the infection from monkey to man.


Subject(s)
Anopheles , Disease Reservoirs , Insect Vectors , Malaria/etiology , Plasmodium malariae/pathogenicity , Animals , Haplorhini , Humans , Nigeria
17.
Science ; 209(4462): 1249-51, 1980 Sep 12.
Article in English | MEDLINE | ID: mdl-6773146

ABSTRACT

The simian guartan malaria parasite Plasmodium inui (OS strain) was cultured in a continuous flow system with rhesus monkey erythrocytes and RPMI 1640nmedium supplemented with Hepes buffer and rhesus serum. Over a 10-week period, the growth of the parasite permitted a 61,000-fold cumulative dilution of the original inoculum. After 5 weeks in culture, the parasites were still infective to the monkey Saimiri sciureus and to Anopheles freeborni mosquitoes.


Subject(s)
Erythrocytes/parasitology , Haplorhini/parasitology , Macaca/parasitology , Plasmodium/growth & development , Animals , Cells, Cultured , Larva , Plasmodium/cytology
18.
Science ; 217(4564): 1048-50, 1982 Sep 10.
Article in English | MEDLINE | ID: mdl-7051285

ABSTRACT

Gametocytes of two strains of the human malaria parasite Plasmodium falciparum have been produced in high density by means of a continuous-flow cultivation system. The gametocytes of these two strains infected a mean of 36 percent and 71 percent, respectively, of Anopheles freeborni mosquitoes that fed on a suspension of red blood cells containing the culture gametocytes. Sporozoites harvested from the infected mosquito salivary glands were infective to the chimpanzee (Pan troglodytes) and the owl monkey (Aotus trivirgatus).


Subject(s)
Plasmodium falciparum/growth & development , Animals , Anopheles/parasitology , Aotus trivirgatus/parasitology , Blood/parasitology , Cells, Cultured , Culture Media , Humans , Pan troglodytes/parasitology , Salivary Glands/parasitology
19.
Science ; 232(4752): 881-4, 1986 May 16.
Article in English | MEDLINE | ID: mdl-3085218

ABSTRACT

A specific DNA probe was used to study the effect of recombinant rat, mouse, and human gamma-interferon (gamma-IFN) on the course of sporozoite-induced malaria infections. In mice and rats infected with sporozoites of Plasmodium berghei, mouse and rat gamma-IFN's strongly inhibited the development of the exoerythrocytic forms in the liver liver cells of the hosts, but not the development of the erythrocytic stages. The degree of inhibition of the exoerythrocytic forms was proportional to the dose of gamma-IFN administered, but was independent of the number of sporozoites used for challenge. A 30 percent reduction in the development of exoerythrocytic forms in rat liver was achieved when 150 units (about 15 nanograms of protein) of rat gamma-IFN were injected a few hours before sporozoite challenge; the reduction was 90 percent or more with higher doses of gamma-IFN. The effect was less pronounced if the gamma-IFN was administered 18 hours before or a few hours after challenge. Human gamma-IFN also diminished the parasitemia in chimpanzees infected with sporozoites of the human malaria parasite Plasmodium vivax. The target of gamma-IFN activity may be the infected hepatocytes themselves, as shown by in vitro experiments in which small doses of the human lymphokine inhibited the development of exoerythrocytic forms of Plasmodium berghei in a human hepatoma cell line. These results suggest that immunologically induced interferon may be involved in controlling malaria infection under natural conditions.


Subject(s)
Interferon-gamma/therapeutic use , Malaria/drug therapy , Animals , Cell Line , Humans , Interferon-gamma/pharmacology , Liver/cytology , Mice , Pan troglodytes , Plasmodium berghei/drug effects , Plasmodium vivax/drug effects , Toxoplasma/drug effects
20.
Science ; 212(4499): 1146-8, 1981 Jun 05.
Article in English | MEDLINE | ID: mdl-7233207

ABSTRACT

The vivax-type simian malaria parasite Plasmodium cynomologi was cultured in vitro by both the candle jar method and the continuous flow technique, with rhesus monkey erythrocytes and RPMI 1640 medium supplemented with Hepes buffer and human serum. After 6 weeks in culture, the growth of the parasite had permitted a 5 X 10(6) cumulative dilution of the original inoculum. Cultured parasites remained infective to rhesus monkeys and exhibited a reversible decrease in the ameboid behavior of their trophozoites.


Subject(s)
Plasmodium/growth & development , Blood , Culture Media , Erythrocytes , Humans , Plasmodium/ultrastructure
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