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Biomedical subjects

B A Robertson

Publications and source records attributed to B A Robertson.

14 recordsLinked to original sources
PubMed1991

Effects of supravital fluorochromes used to analyze the in vivo homing of murine lymphocytes on cellular function.

A number of supravital fluorochromes are available to study lymphocyte homing in vivo. These include fluorescein isothiocyanate (FITC), which binds to cell surface proteins; Hoechst 33342, which binds to AT rich regions of cellular DNA; and the lipid bilayer incorporated dyes PKH-2 and PKH-26. The relative advantages and disadvantages of each of these probes for analyzing murine lymphocyte homing are as yet poorly understood. We evaluated the effects of each dye on labeling efficiency, as well as cell viability, homing, mitogen responsiveness and cytotoxicity. PKH-26 provided long-term labeling (up to 15 days) with the least detrimental effects on cellular function. Detection of FITC in vivo was impaired by tissue autofluorescence, and the dye acted as a co-mitogen for lectin or IL-2-induced proliferation. Hoechst 33342 eluted from cells over a few hours and inhibited lymphocyte proliferation. PKH-2 had detrimental effects on cell viability and resulted in the down-modulation of peripheral lymph node homing receptor expression. None of the probes interfered with the induction of cytotoxic lymphocytes by IL-2. While these fluorochromes are easy to use and provide powerful tools to analyze the lymphocyte localization in vivo, our experiments demonstrate that important limitations are imposed by each probe that need to be considered by investigators during the design and interpretation of experiments.

Animals↗
PubMed1991

Determinants of the reversal time of competitive neuromuscular block by anticholinesterases.

We have assessed, in 200 patients, the determinants of the reversal time of competitive neuromuscular block by anticholinesterase when alcuronium and atracurium neuromuscular block were antagonized by neostigmine 0.04 and 0.08 mg kg-1 and edrophonium 0.5 and 1.0 mg kg-1. A biexponential relationship was found between the reversal time (time from injection of anticholinesterase to a train-of-four ratio of 70%) and the degree of neuromuscular block at reversal (all groups; F ratio, P less than 0.05). Reversal time was determined by two processes: direct antagonism by the anticholinesterase and spontaneous recovery of the neuromuscular blocking agent, with the latter becoming the major determinant at profound levels of neuromuscular block (0-10% of control twitch height). Neostigmine, in the doses studied, appeared to have a higher "ceiling" of neuromuscular block which it completely antagonized, although edrophonium had a more rapid onset of action. The reversal time for alcuronium became progressively longer relative to atracurium as neuromuscular block increased because of the slower spontaneous recovery rate. Avoidance of profound neuromuscular block at the completion of surgery is required to ensure reliable antagonism of the block within 5-10 min by an anticholinesterase. Neostigmine 0.08 mg kg-1 was found to be the most effective agent in antagonizing profound neuromuscular block.

Adult↗
PubMed1990

Human immunodeficiency virus infection in children--prevalence and psychosocial impact.

As at 20 September 1989, 15 children with the acquired immunodeficiency syndrome (AIDS) had been diagnosed in South Africa and indications are that this number is going to increase at a rapid rate in the near future as the disease establishes itself in the heterosexual population. A brief overview of the clinical aspects of human immunodeficiency virus infections in children is given before the psychosocial implications are considered in more detail.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Behavioural screening of 10- and 13-year-old pupils in selected schools in the Cape Peninsula.

The outcome of the behavioural screening of 10- and 13-year-old pupils in selected schools in the Cape Peninsula is reported and the implications discussed. According to parents' reports 21% of 10-year-old and 17.6% of 13-year-old children met the criteria for behaviour disorder. The rates according to teachers' reports were 9.5% and 10.5% respectively. Behaviour disorder occurred with significantly greater frequency among boys, pupils older than the expected age for their standard, pupils with an intelligence quotient below 100, and pupils who had a learning disability.

Adolescent↗
PubMed1987

Outcome of treatment at a psycho-educational day unit for young children.

The outcome of treatment at the psychiatric day centre of the Red Cross War Memorial Children's Hospital in Cape Town is described. Forty-five children were followed up for 2-6 years after discharge--12 were asymptomatic, 22 moderately improved and 11 unimproved. Possible means of improving outcome are discussed.

Adaptation, Psychological↗
PubMed1987

Alpha-melanocyte-stimulating hormone exhibits target cell selectivity in its capacity to affect interleukin 1-inducible responses in vivo and in vitro.

The ability of i.v.-administered recombinant human interleukin 1 (IL 1 beta) to increase core body temperature, stimulate an increased production of serum amyloid P substance, and augment blood levels of circulating neutrophils in mice was inhibited in a dosage-dependent manner by administration of the neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH). alpha-MSH administration was also capable of inhibiting the capacity of i.v.-administered IL 1 beta to enhance plasma levels of corticosterone and to depress the generation and/or elicitation of contact hypersensitivity responses to skin-reactive chemicals. An analog of alpha-MSH (Nle4, D-Phe7 alpha-MSH), known to be more potent than native alpha-MSH in a number of melanotropin-sensitive systems, was determined to be more active than alpha-MSH in the modification of these same in vivo responses. Neither alpha-MSH nor its analog were capable of altering the capacity of IL 1 to stimulate increased plasma levels in prostaglandin E2 (PGE2). In vitro, neither alpha-MSH nor its analog were capable of reducing the capacity of IL 1 to stimulate fibroblast production of PGE2 or to augment the proliferation of murine thymocytes exposed to phytohemagglutinin. The apparent selectivity associated with the regulatory influences of alpha-MSH on IL 1-induced responses in vivo suggests that this neuropeptide may function as an endogenous inhibitor of certain immunomodulatory and inflammatory activities of the cytokine IL 1.

Animals↗
PubMed1987

Marrow ablative doses of gamma-irradiation and protracted changes in peripheral lymph node microvasculature of murine and human bone marrow transplant recipients.

Gamma-irradiation has been extensively utilized as a bone marrow ablative agent during human bone marrow transplantation. Although the effects of ionizing radiation on lymphoid and hematopoietic cells are well documented, little is currently known about its effect on the nonhematopoietic tissues which are important for the restoration of normal immune function. The vast majority of lymphocyte movement into peripheral lymph nodes takes place via the bloodstream and requires a specific receptor-ligand interaction between the lymphocyte and anatomically distinct postcapillary venules. Due to the importance of lymphocyte recirculation in the initiation and amplification of immune responses, an understanding of the radiosensitivity of the postcapillary venules may provide insight into the pathogenesis of the immune deficiencies commonly seen after bone marrow transplantation. Our studies disclosed that the ability of normal blood-borne lymphocytes to enter peripheral lymph nodes was markedly depressed (less than 50% of normal) in mice which had been exposed to 7.5 Gy of gamma-irradiation. This radiation-induced effect lasted longer than 6 months after irradiation and syngeneic reconstitution, and its magnitude was radiation-dose dependent. Immunochemical staining of the lymph node microvasculature with the monoclonal antibody MECA-325 established that the radiation protocol induced persistent anatomic changes in the lymphocyte-receptive areas of endothelium (high endothelial venules). These vessels developed the appearance of endothelial cell proliferation. Electron microscopy demonstrated significant intracellular edema, with virtual occlusion of many microvascular lumens by edematous endothelial cells. Lymph nodes from human bone marrow transplant recipients were found to exhibit similar ultrastructural changes. These studies for the first time demonstrate that doses of irradiation similar to those used to prepare bone marrow transplant recipients can have significant anatomic and functional sequellae on host endothelial cells.

Animals↗
PubMed1986

Neuropeptide regulation of interleukin-1 activities. Capacity of alpha-melanocyte stimulating hormone to inhibit interleukin-1-inducible responses in vivo and in vitro exhibits target cell selectivity.

alpha-Melanocyte stimulating hormone (alpha-MSH), a 13 amino acid neuropeptide produced by the pituitary gland, was found to markedly inhibit the capacity of exogenously administered interleukin-1 (IL-1) to stimulate the enhanced synthesis of acute-phase proteins and induce neutrophilia in vivo. The administration of ACTH or glucocorticosteroids lacked most of these direct IL-1 inhibitory properties. Therefore, in addition to the previously reported antipyretic action of alpha-MSH, this hormone can also inhibit two other known IL-1 sensitive cellular targets in vivo. Further, alpha-MSH was incapable of modifying the comitogenic influence of IL-1 on murine thymocytes or on an IL-1 responsive T-cell line. These findings suggest a target cell specificity to the IL-1 inhibitory activities of alpha-MSH and fail to support the hypothesis that alpha-MSH functions through competitive inhibition of specific cellular receptors for IL-1.

Adrenocorticotropic Hormone↗
PubMed1983

Physically abused children and their families. A 5-year follow-up study.

Thirty-two Coloured families were assessed 5 years after their referral to the Red Cross War Memorial Children's Hospital, Cape Town, because of the physical abuse of one of their children. Although continuation of the physical abuse was not found at follow-up, in two-thirds of the families the environment was as bad as or worse than it had been in 1977, and emotional abuse prevailed. Many of the parents had separated, and 3 of the children had been placed in foster care. The difficulties involved in managing multiproblem families are discussed.

Child↗
PubMed1979

Follow-up study of children admitted to a psychiatric day centre.

A follow-up study of the first 20 children admitted to the Red Cross War Memorial Children's Hospital Day Centre for emotionally disturbed children is described. The psychiatric status of the children and their families was evaluated at admission, discharge and follow-up. The results indicate that younger children benefit more than older ones from day hospital treatment, and that more attention must be paid to the psychiatric needs of the family as a whole.

Adolescent↗
PubMed1977

The child in hosptial.

The characteristic emotional reactions of the young child upon admission to hospital, and the long-term effects on his personality, are described. Children's attitudes to anaesthesia, pain, surgery and immobilization are examined. Guidelines are give for the minimization of emotional trauma whenever possible.

Adolescent↗
PubMed1976

Transcultural factors in child abuse.

A transcultural analysis of 54 cases of child abuse that were consecutively referred to the psychiatric clinic of the Red Cross War Memorial Children's Hospital is presented. Among the data studied were the legal status of the abused child, the nature of the injuries received and the characteristics of the abusers. It is stressed that this was a pilot investigation, and that there is a need for better reporting and further research.

Black or African American↗