The Complexity of the Seasonality of Nutritional Status: Two Annul Peaks in Child Wasting in Eastern Chad

BACKGROUND

Understanding seasonal patterns in nutritional status is critical for achieving and tracking global nutrition goals. However, the majority of nutrition seasonality research design draws on 2 or 3 within-year time points based on existing assumptions of seasonality, missing a more nuanced pattern.

OBJECTIVE

We aimed to identify the intra-year variability of childhood wasting, severe wasting, and weight-for-height z-scores (WHZ) in a dryland single wet-season context and illustrate an analytical approach for improving analysis of the seasonality of nutritional status.

METHODS

To quantify the intra-year variability in nutritional status, we use data from a 23-month panel study (May 2018 to March 2020) following 231 children (6-59 months of age) in eastern Chad. We apply a mixed-effects harmonic regression with child- and village-level fixed effects on the odds of being wasted, severely wasted, and on WHZ, testing for multiple and nonsymmetrical seasonal peaks, adjusted for child sex and age. We triangulate our findings using climate data on temperature, vegetation, and precipitation.

RESULTS

We identify 2 annual peaks of wasting and severe wasting. Wasting peaks at 14.7% (confidence interval [CI], 11.8-18.2) at the end of the dry season, while the smaller peak corresponds to the start of the harvest period at 13.4% (CI, 10.7-16.6). The odds of being wasted decline during the rainy season to 11.8% (CI, 9.4-14.7), with the lowest prevalence of 8.8% (CI, 6.9-11.1) occurring during the start of the dry season. In addition, a 1°C monthly increase in temperature is significantly associated with a 5% (CI, 1.4-8.7) and 12% (CI, 3.0-20.3) increase in the odds that a child is wasted and severely wasted, respectively.

CONCLUSIONS

Intra-year variability of child wasting is far more complex and nuanced than identified by the literature, with 2 peaks, as opposed to 1, likely corresponding to different seasonal drivers, such as food insecurity, disease, water contamination, and care practices at different times of year. Better seasonality analysis can go a long way in improving the timing and content of programming with the goal of reducing child wasting.

Seasonality of Acute Malnutrition in African Drylands: Evidence From 15 Years of SMART Surveys

Reduction of wasting, or low weight-for-height, is a critical target for the Zero Hunger Sustainable Development Goal, yet robust evidence establishing continuous seasonal patterns of wasting is presently lacking. The current consensus of greatest hunger during the preharvest period is based on survey designs and analytical methods, which discretize time frame into preharvest/postharvest, dry/wet, or lean/plenty seasons. We present a spatiotemporally nuanced study of acute malnutrition seasonality in African drylands using a 15-year data set of Standardized Monitoring and Assessment of Relief and Transition surveys (n = 412,370). Climatological similarity was ensured by selecting subnational survey regions with 1 rainy season and by spatially matching each survey to aridity and livelihood zones. Harmonic logit regression models indicate 2 peaks of wasting during the calendar year. Greatest wasting prevalence is estimated in April to May, coincident with the primary peak of temperature. A secondary peak of wasting is observed in August to October, coinciding with the primary peak of rainfall and secondary peak of temperature. This pattern is retained across aridity and livelihood zones and is sensitive to temperature, precipitation, and vegetation. Improved subnational estimation of acute malnutrition seasonality can thus assist decision makers and practitioners in data-sparse settings and facilitate global progress toward Zero Hunger.

Community Clustering of Food Insecurity and Malnutrition Associated With Systemic Drivers in Chad

BACKGROUND

Chad suffers from protracted hunger, facing high food insecurity (Integrated Food Security Phase Classification 3 and above), and acute malnutrition levels that surpass the emergency threshold (15% global acute malnutrition) yearly. The Food Security Sector, with European Union support, leads an inclusive effort to increase synergy between humanitarian, development, and peace-building actors to understand and address drivers of hunger.

OBJECTIVE

To understand the spatial distribution of child wasting and household food insecurity and systemic drivers (conflict, livelihoods, vegetation, cultural norms) as well as better understand the relationship between child wasting and household food insecurity in Kanem and Bahr el Ghazal (BeG) region, Chad, with the goal of improving nexus programming and targeting.

METHODS

A cross-sectional randomized cluster survey was conducted in August 2021 in Kanem and BeG across 86 villages, reaching 7002 households and 6136 children. Data were collected on child anthropometry, household food security, and livelihoods. Using mixed methods, primary data were triangulated with secondary geospatial data on vegetation index and conflicts as well as qualitative interviews with local actors. Analysis was conducted using comparison tests, linear and logistic crude, and adjusted models, as well as looking at the design effect as a measure of clustering of outcomes at the community level.

RESULTS

The geospatial distribution of hunger indicators shows child wasting and food insecurity are highly clustered. However, communities with a high prevalence of child wasting were not those with the highest levels of food insecurity, indicating different pathways. Clustering of food insecurity and child wasting is due to basic drivers of conflict, health, and seasonal access to natural resources.

CONCLUSIONS

The high levels of food insecurity and child wasting are each concentrated in specific survey clusters and are not necessarily connected. They result from different causal pathways at the community level linked to the systemic drivers of the rule of access to natural resources, environmental seasonality, and livelihoods. This suggests a greater need for an integrated humanitarian, development, and peace-building interventions to address the persistent high prevalence of food insecurity and child wasting. It also suggests that these community-level and systemic drivers require greater consideration from the start in research design and data collection.

International humanitarian law violations in northern Uganda: victims' health, policy, and programming implications

Experience of serious violations of International Humanitarian Law (IHL) results in complex physical disability and psychosocial trauma amplifying poverty and multi-generational trauma and impeding long-term recovery. We use data from a representative sample of victims in the case Prosecutor V. Dominic Ongwen brought before the International Criminal Court. Thirteen years after the 2004 massacre, the victims were significantly worse off than the general war-affected population that did not experience serious violations of IHL. The differences in health and wellbeing persisted for individuals and their households, including children born after the massacre. The victims have significantly lower availability of appropriate health services and medications, including significantly greater distance to travel to these services. These findings call attention to the needs of people having experienced IHL violations, for provision of physical and emotional trauma care to allow for recovery, and better understanding of the short- and long-term impacts of IHL violations.

A multi-country, prospective cohort study to measure rate and risk of relapse among children recovered from severe acute malnutrition in Mali, Somalia, and South Sudan: a study protocol

BACKGROUND

The Community-Based Management of Acute Malnutrition (CMAM) model transformed the treatment of severe acute malnutrition (SAM) by shifting treatment from inpatient facilities to the community. Evidence shows that while CMAM programs are effective in the initial recovery from SAM, recovery is not sustained for some children requiring them to receive treatment repeatedly. This indicates a potential gap in the model, yet little evidence is available on the incidence of relapse, the determinants of the phenomena, or its financial implications on program delivery.

METHODS

This study is a multi-country prospective cohort study following "post-SAM" children (defined as children following anthropometric recovery from SAM through treatment in CMAM) and matched community controls (defined as children not previously experiencing acute malnutrition (AM)) monthly for six months. The aim is to assess the burden and determinants of relapse to SAM. This study design enables the quantification of relapse among post-SAM children, but also to determine the relative risk for, and excess burden of, AM between post-SAM children and their matched community controls. Individual -, household-, and community-level information will be analyzed to identify potential risk-factors for relapse, with a focus on associations between water, sanitation, and hygiene (WASH) related exposures, and post-discharge outcomes. The study combines a microbiological assessment of post-SAM children's drinking water, food, stool via rectal swabs, dried blood spots (DBS), and assess for indicators of enteric pathogens and immune function, to explore different exposures and potential associations with treatment and post-treatment outcomes.

DISCUSSION

This study is the first of its kind to systematically track children after recovery from SAM in CMAM programs using uniform methods across multiple countries. The design allows the use of results to: 1) facilitate understandings of the burden of relapse; 2) identify risk factors for relapse and 3) elucidate financial costs associated with relapse in CMAM programs. This protocol's publication aims to support similar studies and evaluations of CMAM programs and provides opportunities for comparability of an evidence-based set of indicators for relapse to SAM.

The One Nutrition in Complex Environments (ONCE) study protocol: a cluster-randomized multi-level multi-sectoral intervention to improve nutrition in Uganda

Objective

To implement and measure the effects of a multi-level multi-sectoral social behavior change (SBC) intervention in Agago District of Northern Uganda and to determine the potential for scale-up.

Intervention

Compare the Nutrition Impact and Positive Practice (NIPP) approach to a NIPP+ approach. The NIPP approach involves nutrition education and SBC, whereas the NIPP+ adds agricultural inputs, training, and tools to support improved farm and water quality practices. The intervention effect will be measured through lower levels of aflatoxin in grain, lower water contamination, and improved knowledge on nutrition and health.

Design

This is a three-arm cluster-randomized controlled superiority trial (cRCT). The study arms include the following: group 1: NIPP; group 2: NIPP+, and group 3: control. Groups 1 and 2 will receive a 12-week intervention (NIPP or NIPP+) with active monitoring and longitudinal follow-up at 2, 6, and 12 months post-intervention. Additionally, an in-depth process and performance evaluation of each intervention arm will be undertaken using quantitative and qualitative methods. A total of 60 clusters from 5 subcounties of the Agago district will be randomly selected, and 15 households per cluster will be recruited using specific inclusion/exclusion criteria for a total of 900 households (300/arm). Respondents for the qualitative portion will be purposely selected.

Analysis

We will collect data from all participants at 3 time points: baseline, endline, and 12 months post-intervention. The analysis will utilize intent-to-treat (ITT) using the initial randomization of the treatment arms to determine the overall impact of having the NIPP vs. NIPP+ vs. control. Mixed effects models will be used to determine the role of time-variant and invariant individual household, and community characteristics, as well as measures of exposure and integration on key outcome indicators. A difference-in-difference analysis (baseline/endline, baseline/12 months post-intervention, endline/12 months post-intervention) will also be used to triangulate findings.

Trial registration

NCT04209569. One Nutrition in Complex Environments (ONCE) Registered 24 December 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06170-7.

Food and Nutrition Systems Dashboards: A Systematic Review

The rapid expansion of food and nutrition information requires new ways of data sharing and dissemination. Interactive platforms integrating data portals and visualization dashboards have been effectively utilized to describe, monitor, and track information related to food and nutrition; however, a comprehensive evaluation of emerging interactive systems is lacking. We conducted a systematic review on publicly available dashboards using a set of 48 evaluation metrics for data integrity, completeness, granularity, visualization quality, and interactivity based on 4 major principles: evidence, efficiency, emphasis, and ethics. We evaluated 13 dashboards, summarized their characteristics, strengths, and limitations, and provided guidelines for developing nutrition dashboards. We applied mixed effects models to summarize evaluation results adjusted for interrater variability. The proposed metrics and evaluation principles help to improve data standardization and harmonization, dashboard performance and usability, broaden information and knowledge sharing among researchers, practitioners, and decision makers in the field of food and nutrition, and accelerate data literacy and communication.

How Seasonality of Malnutrition Is Measured and Analyzed

Seasonality is a critical source of vulnerability across most human activities and natural processes, including the underlying and immediate drivers of acute malnutrition. However, while there is general agreement that acute malnutrition is highly variable within and across years, the evidence base is limited, resulting in an overreliance on assumptions of seasonal peaks. We review the design and analysis of 24 studies exploring the seasonality of nutrition outcomes in Africa's drylands, providing a summary of approaches and their advantages and disadvantages. Over half of the studies rely on two to four time points within the year and/or the inclusion of time as a categorical variable in the analysis. While such approaches simplify interpretation, they do not correspond to the climatic variability characteristic of drylands or the relationship between climatic variability and human activities. To better ground our understanding of the seasonality of acute malnutrition in a robust evidence base, we offer recommendations for study design and analysis, including drawing on participatory methods to identify community perceptions of seasonality, use of longitudinal data and panel analysis with approaches borrowed from the field of infectious diseases, and linking oscillations in nutrition data with climatic data.

Sustained nutrition impact of a multisectoral intervention program two years after completion

Progress on the nutrition Sustainable Development Goals has been slow. More attention is needed on the 'sustainable' part, focused on impact lasting beyond programme implementation. To determine sustained impact of a multisectoral nutrition intervention that provided water, sanitation, hygiene, livelihood, health and nutrition support (2013-2015) in eastern Chad, we utilize longitudinal household data collected 2 years (2017) after the intervention ended. Between 2013 and 2015, children (6-59 months) in the multisectoral intervention were less likely to be severely wasted, underweight and had a higher weight-for-height z-score (WHZ) compared with the control. To measure sustained programme impact, we use data on six nutrition indicators from 517 children between 2015 and 2017. We ran three models: a generalized linear model on cross-sectional child cohorts; a mixed-effects model on household panel data; and a mixed-effects model on child panel data. For children who were born during the programme, we saw significant improvement in underweight, weight for age z-scores (WAZs) and height-for-age z-scores (HAZs). Boys 6-23 months born after the end of the programme, on the other hand, were significantly more likely to be underweight or wasted and had lower WHZ and WAZ compared with boys born during the programme and girls born during and after the programme. Corresponding to the literature from sub-Saharan Africa, boys appear to be more vulnerable to malnutrition, which might be why they are more sensitive to programme cessation. Future monitoring, evaluations and research need to consider impact sustainability and that it might not be homogeneous across age and gender.

Women survivors and their children born of wartime sexual violence in northern Uganda

Girls and women who bear children owing to wartime sexual violence committed by armed actors face challenges in gaining acceptance on return to their families and societies. This study analyses the lives of women survivors and their children born of wartime sexual violence in Uganda. It draws on a population-based survey of 1,844 households in the Acholi and Lango sub-regions of northern Uganda, as well as on in-depth qualitative interviews conducted in 2014 and 2015 with 67 purposefully selected women survivors of wartime sexual violence. The study finds that: stigma is linked to broader gender discriminatory sociocultural norms and practices and changes under different circumstances; women's economic agency is essential to reducing stigma; households with members who suffered war-related sexual violence experienced significantly higher rates of violence post conflict than did other households; and the passage of time is less of a determining factor in their acceptance and reintegration than previously thought.

Observation-based study on aerosol optical depth and particle size in partly cloudy regions

This study seeks to help better understand aerosol-cloud interactions by examining statistical relationships between aerosol properties and nearby low-altitude cloudiness using satellite data. The analysis of a global dataset of MODIS (Moderate Resolution Imaging Spectroradiometer) observations reveals that the positive correlation between cloudiness and aerosol optical depth (AOD) reported in earlier studies is strong throughout the globe and during both winter and summer. Typically, AOD is 30-50% higher on cloudier-than-average days than on less cloudy days. A combination of satellite observations and MERRA-2 global reanalysis data reveals that the correlation between cloud cover and AOD is strong for all aerosol types considered: sulfate, dust, carbon, and sea salt. The observations also indicate that in the presence of nearby clouds, aerosol size distributions tend to shift toward smaller particles over large regions of the Earth. This is consistent with a greater cloud-related increase in the AOD of fine mode than of coarse mode particles. The greater increase in fine mode AOD implies that the cloudiness-AOD correlation does not come predominantly from cloud detection uncertainties. Additionally, the results show that aerosol particle size increases near clouds even in regions where it decreases with increasing cloudiness. This suggests that the decrease with cloudiness comes mainly from changes in large-scale environment, rather than from clouds increasing the number or the size of fine mode aerosols. Finally, combining different aerosol retrieval algorithms demonstrated that quality assessment flags based on local variability can help identifying when the observed aerosol populations are affected by surrounding clouds.

The Relationship Between Acute Malnutrition, Hygiene Practices, Water and Livestock, and Their Program Implications in Eastern Chad

BACKGROUND

The causes of acute malnutrition are complex and time and geography variant and need to be better understood in order to both design more effective nutrition programs and evaluate them. The findings reported here are part of an evaluation of a 4-year multisectoral nutrition program led by Concern Worldwide in the Sila Region of eastern Chad.

OBJECTIVE

To present evidence and learning about the relationships between acute malnutrition and potential drivers in Sila, Chad.

METHODS

Quantitative household-level data from a clustered randomized control trial were collected in November/December 2014. The survey was complemented with water quality testing and qualitative data collected in February and March 2013 and 2014.

RESULTS

Households who reported not regularly cleaning the container used for transporting water for household consumption were almost twice as likely to have a malnourished child. Households living in villages with larger concentrations of cattle and having more livestock sharing the same water source as for human consumption were significantly more likely to have a malnourished child. However, cleaning the water container mediated the negative impact of living in a village with a large cattle concentration on wasting.

CONCLUSION

These results demonstrate that hygiene practices and livestock water management are correlated with acute malnutrition in Sila, Chad. These findings provide a hypothesis for a possible pathogen driving acute malnutrition rates- Cryptosporidium-as part of a complex water chain, whereby the source of infection may be mitigated by hygiene behaviors with important implications for humanitarian programs.

A framework based on 2-D Taylor expansion for quantifying the impacts of sub-pixel reflectance variance and covariance on cloud optical thickness and effective radius retrievals based on the bi-spectral method

The bi-spectral method retrieves cloud optical thickness (τ) and cloud droplet effective radius (r _e ) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved τ and r _e . In the literature, the retrievals of τ and r _e are often assumed to be independent and considered separately when investigating the impact of sub-pixel cloud reflectance variations on the bi-spectral method. As a result, the impact on τ is contributed only by the sub-pixel variation of VIS/NIR band reflectance and the impact on r _e only by the sub-pixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the τ and r _e retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the τ and r _e retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the r _e retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in r _e retrievals, leading to a potential contribution of positive bias to the r _e retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from MODIS. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used to estimate the retrieval uncertainty from sub-pixel reflectance variations in operational satellite cloud products and to help understand the differences in τ and r _e retrievals between two instruments.

THE EFFECT OF X-RAYS ON CHROMOSOMES IN DIFFERENT STAGES OF MEIOSIS

1. Pollen mother cells exposed to low dosages of x-rays at various stages show different frequencies of chromosome abnormalities in the first meiotic anaphase. 2. Maximum frequencies of abnormalities were obtained in buds irradiated in the pachytene stage of the meiotic prophase and in the preceding mitosis. 3. These results are taken to indicate that the x-ray-sensitive portions of the chromonemata are closely approximated in pairs in pachytene and in the early mitotic prophase. The significance of this in relation to non-homologous pairing is indicated. 4. From the nature of the chromosome configurations observed it is concluded that chromonemata are two-parted when they synapse and that a chromonematic division occurs between pachytene and anaphase and during the mitotic prophase. 5. The frequencies of abnormalities show a linear relationship to dosage. 6. The diameter of the sensitive volume of the chromonema is calculated and found to approximate the diameter of some known protein molecules. 7. The linkage mechanism is found to make up about 90 per cent of the total sensitive volume which corresponds with the approximate reduction in length of the chromonema from pachytene to anaphase. 8. The relation of these sensitive volumes to the gene is discussed.

P(32) UPTAKE BY NUCLEI

1. A method for isolating nuclei in quantity from mammalian tissues is described. 2. The rate of uptake of radioactive phosphorus by nuclei is found to be quite rapid. The phosphorus was shown not to be taken up by exchange. 3. Nuclei of tumors accumulate more radioactive phosphorus than normal liver nuclei. This was shown to be due to mitotic activity and not a form of metabolism peculiar to tumor cells. 4. The specific activities of nuclei and cytoplasm are compared. 5. 60 to 70 per cent of the nuclear radioactive phosphorus is present as nucleoprotein from 1 hour to 5 days after it is administered. In the lymphoma nuclei 90-95 per cent of the phosphorus is in the nucleoprotein fraction from 1-5 days after it is administered. 6. The specific activities of the nucleoprotein, lipid, and acid-soluble fractions of liver and tumor nuclei are compared. 7. From the rate of P(32) uptake by nuclei it is calculated that a new lymphoma nucleus is synthesized on the average once every 27 hours. This is in agreement with the observed rate of growth of the tumor. 8. In the lymphoma nucleus it is calculated that 7 x 10(4) molecules of tetranucleotide are synthesized per second. 9. Irradiation with 200 r. x-rays alters the distribution of P(32) in the lymphoma cell, markedly increasing the concentration in the nucleus shortly after irradiation. The P(32) concentration in the cytoplasm decreases with time after irradiation. It is suggested that the altered distribution is correlated with the inhibition of mitosis produced by the x-rays. 10. Continual synthesis of nucleoprotein takes place even in nuclei of cells which do not undergo mitosis.

CHANGES IN THE APPARENT CYTOPLASMIC HYDROGEN ION CONCENTRATION OF AMEBA DUBIA ON INJECTION OF EGG ALBUMIN

1. Egg albumin when injected into an ameba or discharged into the solution about it raises the apparent pH of the cytoplasm of the ameba. 2. With time the cytoplasm returns to the original pH 6.9 if the nucleus is present. Amebae that have received repeated injections of albumin in some cases extrude their nuclei. In these cells the cytoplasm remains at the more alkaline pH induced by the albumin for at least 12 hours. 3. When a 2 per cent solution of albumin is introduced into a suspension of amebae there is a temporary marked rise in the rate at which CO₂ is given off with no corresponding rise in O₂ uptake. 4. The results observed can be explained if the albumin discharged onto the surface of the ameba rapidly enters the cell and there becomes distributed in a phase of the cytoplasm other than the one which contains the phenol red.

Spatio-temporal regulation and cleavage by matrix metalloproteinase stromelysin-3 implicate a role for laminin receptor in intestinal remodeling during Xenopus laevis metamorphosis

The 37-kd laminin receptor precursor (LR) was first identified as a 67-kd protein that binds laminin with high affinity. We have recently isolated the Xenopus laevis LR as an in vitro substrate of matrix metalloproteinase stromelysin-3 (ST3), which is highly upregulated during intestinal metamorphosis in Xenopus laevis. Here, we show that LR is expressed in the intestinal epithelium of premetamorphic tadpoles. During intestinal metamorphosis, LR is downregulated in the apoptotic epithelium and concurrently upregulated in the connective tissue but with little expression in the developing adult epithelium. Toward the end of metamorphosis, as adult epithelial cells differentiate, they begin to express LR. Furthermore, LR is cleaved during intestinal remodeling when ST3 is highly expressed or in premetamorphic intestine of transgenic tadpoles overexpressing ST3. These results suggest that LR plays a role in cell fate determination and tissue morphogenesis, in part through its cleavage by ST3. Interestingly, high levels of LR are known to be expressed in tumor cells, which are often surrounded by fibroblasts expressing ST3, suggesting that LR cleavage by ST3 plays a role in both physiological and pathological processes.

The matrix metalloproteinase stromelysin-3 cleaves laminin receptor at two distinct sites between the transmembrane domain and laminin binding sequence within the extracellular domain

The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. However, like other MMPs, the molecular basis of ST3 function in vivo remains unclear due to the lack of information on its physiological substrates. Furthermore, ST3 has only weak activities toward all tested ECM proteins. Using thyroid hormone-dependent Xenopus laevis metamorphosis as a model, we demonstrated previously that ST3 is important for apoptosis and tissue morphogenesis during intestinal remodeling. Here, we used yeast two-hybrid screen with mRNAs from metamorphosing tadpoles to identify potential substrate of ST3 during development. We thus isolated the 37 kd laminin receptor precursor (LR). We showed that LR binds to ST3 in vitro and can be cleaved by ST3 at two sites, distinct from where other MMPs cleave. Through peptide sequencing, we determined that the two cleavage sites are in the extracellular domain between the transmembrane domain and laminin binding sequence. Furthermore, we demonstrated that these cleavage sites are conserved in human LR. These results together with high levels of human LR and ST3 expression in carcinomas suggest that LR is a likely in vivo substrate of ST3 and that its cleavage by ST3 may alter cell-extracellular matrix interaction, thus, playing a role in mediating the effects of ST3 on cell fate and behavior observed during development and pathogenesis.

Synergy, activity and tolerability of zidovudine and interferon-alpha in patients with symptomatic HIV-1 infection: AIDS Clincal Trial Group 068

Thirty-four subjects with symptomatic HIV-1 infection, p24 antigenaemia, and CD4 cell counts > 200/mm3 were randomly assigned to receive treatment with either zidovudine (ZDV) orally, interferon-alpha (IFN-alpha) subcutaneously, or both at respective low (200 mg ZDV/ 2 million international units IFN-alpha (MIU)), middle (400 mg/4 MIU) or high (600 mg/6 MIU) daily dose levels for 12 weeks. Thereafter, all patients received combination therapy at the initially assigned dose level to a total of 96 weeks. This design permitted analysis by the combination index (CI) method, which demonstrated antiretroviral synergy between ZDV and IFN-alpha with respect to p24 antigen suppression. Over the first 12 weeks, combination therapy was acceptably tolerated, more so than IFN-alpha monotherapy, and it was significantly more active in suppressing antigenaemia than either of the monotherapies. Similarly, the high-dose combination was the most active dose level over weeks 12 to 96. Combination ZDV/IFN-alpha at the optimal dose level defined by this trial merits further study. In addition, the CI design strategy employed here may be useful for the investigation of new antiretroviral combinations.

Tryptic digestion of myosin light chain kinase produces an inactive fragment that is activated on continued digestion

Trypsin digestion of chicken gizzard myosin light chain kinase at limiting trypsin concentrations proceeds in stages. In the first stage, catalytic activity in the presence or absence of calcium and calmodulin decreases. In the second stage, activity in the absence of calcium increases, and the calcium-calmodulin complex no longer stimulates activity. The initial loss of activity is associated with the appearance of a 59,000-Da peptide that has been isolated and shown to have low catalytic activity. This peptide was further digested to a 55,000-Da peptide that has calcium-independent catalytic activity. This peptide has been isolated, and its affinities for the peptide substrate Kemptamide (Lys-Lys-Arg-Pro-Gln-Arg-Ala-Thr-Ser-Asn-Val-Phe-Ser-NH2) and ATP have been shown to be the same as those of the intact enzyme. Neither the 59,000-Da nor the 55,000-Da fragment binds calmodulin.

The control of specificity of cytotoxic T lymphocytes by the major histocompatibility complex (AG-B) in rats and identification of a new alloantigen system showing no AG-B restriction

The regulatory influence of the rat major histocompatibility complex (MHC) (Ag-B complex) on the specificity of cytotoxic T lymphocytes was investigated. It was shown that the effector cells were specific for the original Ag-B phenotype in rat systems in which the responder and stimulator cell populations were unquestionably MHC identical but expressed different minor alloantigens of viral antigens. However, combined in vivo immunization and restimulation in culture of lymphocytes from rat strains previously thought to be MHC compatible resulted in the generation of cytotoxic T lymphocytes which effectively lyse not only target cells from the specific stimulating strains but also, to varying degrees, target cells from third party strains regardless of their Ag-B haplotypes. Genetic analysis indicates that expression of these cytotoxic T-cell-defined ("CT") antigens, found on both T and B lymphocytes, detectable thus far only with cytotoxic lymphocytes, is controlled by a single locus which segregates in backcross populations with the rat MHC. Discrepancies between the nature of CT antigens of the rat Ag-B and I-region specificities of the mouse H-2 are discussed.

Specific selection of cytotoxic effector cells: the generation of cytotoxic T cells in rat thoracic duct lymphocyte populations positively or negatively selected for reactivity to specific strong histocompatibility alloantigens

These studies consider the generation of cytotoxic T lymphocytes (CTL) from precursors (CTLP) present in rat thoracic duct lymphocytes after stimulation with strong alloantigens. Also, they explore the relationship between CTLP and "initiator" (I) lymphocytes responsible for specific GVH and MLI reactions. Positively selected TDL populations prepared in bulk MLI cultures show enriched GVH and MLI reactivity for the selecting major histocompatibility complex (MHC) haplotype, but no cytotoxic activity, raising the possibility that I and CTLP may belong to different subpopulations, and the latter failed to differentiate or to survive under these culture conditions. Restimulation of these cells in Marbrook culture vessels with the original priming haplotype under conditions suitable for generating killer cells in vitro resulted in greatly increased specific CTL activity with accelerated kinetics soon after priming and normal kinetics later. These findings indicate that "memory" killer cells can be generated in a previously stimulated lymphocyte population that had no overt cytotoxic activity. Restimulation with third party haplotypes failed to give CTL activity either to specific or to third party targets. Negatively selected TDL populations prepared by "filtration" through x-irradiated F1 rats, depleted of specific GVH and MLI responses, were also depleted of the ability to generate CTL in Marbrook cultures stimulated with the selecting haplotype. Stimulation with third party haplotypes, or with both third party and specific haplotypes together, gave CTL effective only against the third party target.

SPECIFIC positive and negative selection of rat lymphocytes reactive to strong histocompatibility antigens: activation with alloantigens in vitro and in vivo

This study compares the functional properties of rat thoracic duct lymphocytes (TDL) after stimulation with strong alloantigens of the major histocompatibility complex (MHC) either in vitro in preparative mixed lymphocyte interactions (MLI) or in vivo in systemic graft-vs-host (GVH) reactions. Comparisons were made of PHA responses and reactivity to the specific priming haplotypes or to third party haplotypes in analytical MLI and in GVH reactions either before or after the activated populations were "parked" in syngenetic T cell-deprived (B) rats. These comparisons can be summarized as follows: 1) TDL populations primed in bulk MLI cultures (MLI-TDL) slowed some evidence of specific positive selection when tested immediately; MLI responses to specific alloantigens were both relatively large and accelerated in tempo, whereas responses to third party alloantigens were diminished but also accelerated in tempo. Specific GVH responses were more marked than in third party recipients but they were also decreased relative to normal, and displayed an abberant dose/response slope. MLI-TDL populations tested after they had been stored in syngeneic B rats showed clear evidence of stable-specific positive selection; specific MLI and GVH responses were enriched relative to third party responses and also in comparison to normal, unselected TDL populations. This finding indicates that GVH and MLI reactivity are probably both functional capacities of the same lymphocyte subpopulation since positive selection by one function (MLI) also enriched for a second (GVH). 2) Parental strain TDL activated in vivo in the systemic GVH reaction in irradiated F1 animals and recovered from the thoracic duct 3 to 4 days later (late GVH-TDL) consisted mainly of blast cells, however, in contrast to MLI-TDL these populations showed no evidence of positive selection when tested before or after parking in B rats. MLI responses to specific alloantigens were minimal, and greatly reduced in magnitude compared to normal. GVH responses to specific haplotypes could be detected, but these were not enriched compared to normal, despite the content in the late GVH-TDL populations of a significant proportion of blast cells presumably activated by host alloantigens. 3) Early collections (less than 40 hr) of parental strain GVH-TDL collected from F1 recipients contained no blast cells and showed impressive degrees of negative selection; they were markedly depleted of both GVH and MLI activity to specific alloantigens but displayed normal reactivity to third party alloantigens. Moreover, specific negative selection was persistent in these populations parked for several weeks in B rats, and indication that a specific subpopulation of reactive cells had been physically eliminated. 4) PHA responses of both MLI- and GVH-activated TDL populations tested either before or after parking in B rats were approximately normal on a per T cell basis...