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Biomedical subjects

S J Parker

Publications and source records attributed to S J Parker.

11 recordsLinked to original sources
PubMed1992

Outcome after developmental intervention in the neonatal intensive care unit for mothers of preterm infants with low socioeconomic status.

The efficacy of developmental intervention in the neonatal intensive care unit for mothers of preterm infants with low socioeconomic status was evaluated. Mothers were assigned to an experimental group in which they met at least weekly with an infant-development specialist or to a control group in which they did not. During the sessions, they participated in a structured developmental and behavioral assessment of their infants, with the goal of enhancing their ability to provide appropriate interactions and environmental stimulation for their infants. When the infants were 4 and 8 months of age, follow-up home visits by a nurse who was unaware of group assignment showed that the experimental-group infants performed more optimally on the Bayley Mental scale (Bayley Scales of Infant Development) at 4 and 8 months of age and on the Bayley Motor scale at 4 months. In addition, the home environment was more developmentally appropriate at 4 months of age, and the mothers rated their babies as temperamentally less difficult at 4 and 8 months. We conclude that a mother-focused, neonatal intensive care unit-based program that utilizes the assessment process in a therapeutic way is an effective strategy in the initiation of interventions for families of low socioeconomic status whose infants were born prematurely.

Adult↗
PubMed1992

Maternal Type A behavior during pregnancy, neonatal crying, and early infant temperament: do type A women have type A babies?

It was hypothesized that type A behavior in pregnant women would be associated with increased neonatal crying and differential reports of infant temperament at 3 months. Type A behaviors during pregnancy were measured in a self-selected cohort of 72 healthy, primiparous, middle-class women. Their newborns were assessed at 48 hours of age and the women completed an infant temperament questionnaire at 3 months. Women who were classified as type A on the Job Involvement scale of the Jenkins Activity Survey had infants who cried more during a standardized neurobehavioral assessment compared with infants of women who were type B on the same scale. Women who were type A for Job Involvement rated their 3-month-old infants as more intense and less predictable in their responses to the environment. They were also more likely to be breast-feeding their infants at 3 months. This is the first study to examine the prevalence and nature of maternal type A behaviors during pregnancy and to show their relationship to neonatal crying behavior, to maternal report of early infant temperament, and to maternal breast-feeding.

Adult↗
PubMed1991

CD8+ T cells are the major lymphocyte subpopulation involved in the protective immune response to Toxoplasma gondii in mice.

The ability of the major T cell subsets to adoptively transfer resistance to T. gondii infection was studied. Spleen cells harvested from mice with a 3-month T. gondii infection and cells from uninfected mice were enriched for T cells by nylon/wool purification. Adoptive transfer of these cells from both groups of donor mice led to a significant increase in the survival of syngeneic recipient mice infected intraperitoneally with 20 T. gondii cysts. Increased survival was mediated particularly by CD4-depleted but also, to a lesser extent, CD8-depleted subpopulations. These results were confirmed in T cell reconstituted athymic nude mice. Unfractionated T cells from chronically infected donors produced a significant inhibition of cyst formation in the brains of recipient mice measured 10 weeks after infection compared with control mice. The inhibition of cyst formation was ablated by pretreating T cells with anti-CD8 antibody and complement, but not anti-CD4 antibody and complement. Mice receiving cells from infected donors produced an early increase in their IgG1 and IgG2a antibody titres compared with mice given cells from uninfected animals. The depletion of either CD8+ or CD4+ immune cells appeared to have little effect on the antibody responses in recipient mice and there was no correlation between antibody levels and immunity. The results indicate that CD8+ T lymphocytes from convalescent T. gondii-infected BALB/c mice are the principal mediators of resistance to T. gondii, although CD4+ T cells appear to be involved during the acute phase of infection.

Animals↗
PubMed1991

Murine immune responses to recombinant Toxoplasma gondii antigens.

Recombinant proteins of the RH strain of Toxoplasma gondii were produced by expression in Escherichia coli as glutathione S-transferase (GST) fusion proteins. Enzyme-linked immunosorbent assays were established using 2 of these fusion proteins termed H4/GST and H11/GST. The assays were able to detect antibodies in the sera of mice orally infected with either the cyst or oocyst stage of a pork isolate of T. gondii. In addition, the sera from mice infected with 1 of 4 different T. gondii isolates were investigated for their binding to these fusion proteins. Antibodies in the sera of all mice bound to H11/GST, but not all sera recognized H4/GST. Delayed-type hypersensitivity (DTH) responses to the fusion proteins were found when the mice were sensitized intradermally with H4/GST and H11/GST and challenged with the homologous fusion protein. However, no DTH response was recorded when mice were challenged with homologous fusion proteins after infection with T. gondii, or after immunization with a sonicate of the RH strain of the parasite. In addition, cellular responses were not stimulated against either of the fusion proteins in in vitro assays. These 2 fusion proteins were recognized by anti-T. gondii antibodies in experimental murine infections, and they are therefore potential candidates as antigens in assays for the diagnosis of human toxoplasmosis.

Animals↗
PubMed1990

Heligmosomoides polygyrus: influence of infection on lymphocyte subpopulations in mouse mesenteric lymph nodes.

The immune response to a primary infection of Heligmosomoides polygyrus (Nematospiroides dubius) was studied by flow cytometry in three strains of mice, BALB/c, CBA, and NIH. The chief feature of the response was a pronounced increase, during the first week, in the proportion of B lymphocytes in the mesenteric lymph nodes. All three strains also showed an increase in lymph node cellularity, although this was delayed in NIH and CBA mice. Total B cell numbers thus also increased, particularly in the BALB/c and NIH strains but only in the latter was this response maintained throughout the 4-week study. Although the early changes in B cell frequency were similar in all three strains, B cell responses were greatest in BALB/c mice, and most prolonged in NIH, when they persisted into the adult phase of the infection. These features distinguished them from CBA mice, and could be associated with known variations in resistance to challenge infections. An increase in T cell numbers was delayed in comparison with the changes in the B cell population, and the ratio of 'helper' to 'suppressor/cytotoxic' T cells remained more or less constant in all three strains. There was thus no evidence for an increase in the frequency of suppressor T cells in any strain of mouse.

Animals↗
PubMed1990

Early lymphocytic responses to Heligmosomoides polygyrus infections in mice.

Responses to parasite antigens were studied in three strains of mice, BALB/c, CBA and NIH, during the initial phases of a primary infection with the intestinal nematode Heligmosomoides polygyrus. Changes in the rate of in vivo cell division were analysed in mesenteric lymph nodes and spleens during the phases of larval maturation and adult establishment, and related to changes in organ size and cellularity. The nature of the proliferating cell populations was also investigated by flow cytometry, carried out on cell suspensions prepared at the time when larval development was complete. The variation in the ability of the strains of mice to become resistant to a challenge infection was manifest as only slight differences in their initial responses to infection. All three strains showed an increase in 125I-iododeoxyuridine incorporation in their mesenteric lymph nodes and spleen, and an increase in B cell frequency over that of T cells in the draining lymph nodes. Although lymph node weight in NIH mice continued to rise over a 4 week period, the majority of responses measured were short lived, peaking 10 to 14 days after infection. The low responder status of CBA mice was thus reflected in a transient and relatively small enlargement of lymphoid tissues, but their early proliferative responses to antigen were similar in scale to those of responder strains.

Animals↗
PubMed1990

The resource dependence of a county nursing department: efforts to thrive in the 1980s.

This case study documents analysis and planning in a contemporary public health nursing organization using resource dependence organizational theory. Several internal and external factors affect the organization and its relationships with its resources. We attempted to use knowledge of the environment-organization relationship in several ways. Three examples from inside and outside the county system demonstrate opportunities for nursing to decrease the organization's traditional resource dependence and expand its base of funding and influence. Application of this theory can assist other organizations to adapt and survive in this era of diminishing health care resources.

Health Resources↗
PubMed1988

Brain GABAA/benzodiazepine binding sites and glutamic acid decarboxylase activity in depressed suicide victims.

We have investigated the involvement of gamma-aminobutyric acid (GABA) in depression by quantitating benzodiazepine (BZ) binding sites, the ability of GABA to stimulate BZ binding and glutamic acid decarboxylase activity in frontal and temporal cortex obtained at postmortem examination from 21 suicide victims and 21 age- and sex-matched controls. We limited our study to suicide victims with clear evidence of depression, in the absence of symptoms of other psychiatric disorders. Thirteen of the depressed suicide victims had not been prescribed psychoactive drugs recently and none were found in their blood at postmortem; of the remaining 8 suicides, 6 were receiving antidepressant drugs, alone or in combination with other drugs. The number of BZ binding sites was significantly greater (by 18%) in the frontal cortex of the total group of depressed suicides compared to controls, but did not differ in the temporal cortex. The increase in the number of BZ binding sites in the frontal cortex was of similar magnitude when drug-free (16%), drug-treated (21%) and antidepressant-treated suicides (16%) were compared to matched controls, although the increase was only statistically significant for the drug-treated suicides. The Kd of BZ binding and the ability of GABA to stimulate BZ binding did not differ significantly between controls and the total, drug-free, drug-treated or antidepressant-treated suicides in either cortical area. Glutamic acid decarboxylase activity did not differ significantly between control and suicide groups, but was markedly reduced in subjects dying by carbon monoxide poisoning. The present study provides evidence for a greater number of BZ binding sites in the frontal cortex of depressed suicide victims, which could not clearly be attributed to drug treatment.

Adult↗