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Biomedical subjects

J Allan

Publications and source records attributed to J Allan.

106 records · Page 6Linked to original sources
PubMed1979

Pathway-dependent reconstitution of chromatin structure from separated constituents.

Chicken reticulocyte chromatin can be reassembled from its separated constituents, viz. DNA, H1 plus H5, core histones, and non-histone proteins, to yield a product resembling the native starting material by a series of structural criteria. In particular, it possesses nucleosomes separated by spacer regions; the particles contain DNA with a unit length of approximately 200 base pairs. The recovery of the correctly reassembled product depends critically on the annealing conditions: the components are initially mixed in 2 M NaCl and 5 M urea, and it seems to be important to remove urea at a relatively high salt concentration. The results suggest that the characteristic chromatin structure is formed only when core histones bind to DNA in their native conformation and are followed by the addition of H1 and H5 to the spacer regions.

Animals↗
PubMed1976

The role of sarcolemma and mitochondria in regulating Ca2+ movements in human myometrium.

A subcellular fraction enriched in sarcolemma was isolated by differential and sucrose gradient centrifugation from human myometrium. The Ca2+ binding characteristics of this fraction were compared to that of mitochondria and microsomes that were isolated simultaneously. 1. Oxalate increased ATP-dependent Ca2+ uptake by the sarcolemmal but not the mitochondrial fraction, while azide inhibited mitochondrial but not sarcolemmanl Ca2+ transport. 2. The amount of Ca2+ bound in 10 min by these two fractions from a 0.3 muM free Ca2+ solution was similar, but the rate of Ca2+ uptake at 1 muM Ca2+ was greater for the mitochondrial than the sarcolemmal. fraction. The properties of Ca2+ binding by the microsomal fraction were intermediate between these two fractions. 3. The results suggest that mitochondria have a greater potential for lowering intracellular Ca2+ activity in human myometrium than do sarcolemma or sarcoplasmic reticulum.

Adult↗
PubMed1973

Spectrum of asthma in children. 3. Psychological and social components.

Behavioural disturbances in the child, the mother-child and family relationships, and the family social structure were studied in a representative sample of the whole range of asthmatic children and compared with a control group of normal children. Behavioural disturbances occurred more often and at a statistically significant level only in the small group of children with severe and continuing asthma. These children were those with severe chronic airways obstruction as assessed physiologically and also with the most severe allergic manifestations.Predominant in the mother-child relations was an over-concern to protect the child's health in those children with continuing asthma at 14 years of age. The families of the very severely affected group of children showed evidence of more stress than other families. Socioeconomic conditions were not significantly different in any group of asthmatic children compared with the control group.

Adolescent↗
PubMedDate not supplied

Selective unfolding of erythroid chromatin in the region of the active beta-globin gene.

Globin gene expression, which occurs exclusively in the erythroid cell lineage, is controlled at the level of transcription. It is thus of some considerable interest to compare the chromatin structure of this gene with that of inactive genes in erythroid cell nuclei and to compare the chromatin structure of the globin gene in its active and inactive states in nuclei of different cell types. Other workers have observed that globin genes in erythroid cell nuclei exhibit the enhanced overall sensitivity to nucleases and the hypersensitive site in the 5'-flanking sequence typical of many active genes. The nature of the structural changes giving rise to nuclease sensitivity are however obscure. We have investigated the local higher order structure of chromatin in the region of unique genes in chicken by sucrose gradient sedimentation of chromatin restriction fragments. We find that ovalbumin and alpha 2-collagen gene fragments in erythrocyte chromatin and an adult beta-globin gene fragment in spleen chromatin sediment with bulk chromatin fragments of the same DNA size, whereas the beta-globin gene fragment in erythrocyte chromatin sediments more slowly than bulk fragments of equivalent size. The simplest interpretation of the results is that the solenoid structure in the region of the globin gene is selectively and permanently unfolded on gene activation.

Animals↗
PubMedDate not supplied

Mothers' explanatory models of lack of child growth.

This qualitative study elicited the explanatory models (EMs) of child growth held by mothers of growth-deficient children. EMs are culturally constructed explanations for a specific illness and its treatment (Kleinman, 1980). The EM concept was adapted for this study to focus on a child health condition instead of an illness. The sample comprised 22 mothers of growth deficient children who were interviewed 2 years after the conclusion of an intervention study to promote child growth. Growth deficiency was defined as below the 10th percentile for weight, height, or weight for height on the National Center for Health Statistics (NCHS) growth grids (Hamill, Drzid, Johnson, Reed, & Roche, 1976). Three major domains were identified in the EMs of growth held by mothers: (1) illness or heredity (etiology); (2) keeping track of growth (course); and (3) helping my child grow (treatment). The mothers in this study were concerned about their children's size and growth patterns and they monitored their children's growth with the methods available to them. They identified illnesses and allergies as environmental factors that negatively impact their children's growth. All mothers viewed size as a function of heredity. The findings from this study suggest that an emphasis on size will not encourage mothers to focus on their children's growth. The EMs for growth and size were different. Health care providers may be more effective in enhancing children's growth by teaching parents how to deal with the day-to-day problems of children who are picky eaters, stretching limited food money, creating mealtime schedules, and dealing with illnesses before they become severe.

Child↗
PubMedDate not supplied

Low-income mothers' perceptions of health in their children with growth delay.

ISSUES AND PURPOSE: Parental characteristics are the strongest predictor of poor health for children. This study examined how low-income mothers of children with growth delay define health for their children, and the behaviors they use to monitor their children's health. DESIGN AND METHODS: Naturalistic design using Kleinman's Explanatory Model approach and interviews with 22 mothers. RESULTS: Mothers consider nutritious food as a primary contributor to their children's health and consider healthy children to be chubby. Other indicators of health include children's energy levels, provision of nutritious food, and physical and mental activity balanced with rest. PRACTICE IMPLICATIONS: A mother's explanatory model of health for her child can guide health promotion targeted to the mother's beliefs.

Adult↗
PubMedDate not supplied

Absence of antibodies to HTLV-III in health workers after hepatitis B vaccination.

A proportion of the plasma for the triply inactivated, plasma-derived hepatitis B vaccine produced in the United States is obtained from homosexual men. Because homosexual men are a high-risk group for the acquired immunodeficiency syndrome (AIDS), concern has emerged that the vaccine could harbor the AIDS agent. To evaluate this risk, we tested 15-month postvaccination serum samples for antibodies to human T-cell lymphotropic virus type III in 100 health care workers who had received inactivated hepatitis B vaccine lots made from plasma collected between 1977 and 1979 and 100 who had received placebo injections. None of the 200 health workers had serological evidence of human T-cell lymphotropic virus type III infection. These serological findings lend additional support to earlier epidemiologic and immunologic observations suggesting that hepatitis B vaccine does not transmit infection with an AIDS virus.

Antibodies, Viral↗