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Biomedical subjects

J White

Publications and source records attributed to J White.

At least 433 records · Page 24Linked to original sources
PubMed1989

Severe envenomation with convulsion following multiple bites by a common brown snake, Pseudonaja textilis.

A case report of envenomation by a common brown snake, Pseudonaja textilis, in a 3.3 year old boy is presented. He suffered a brief grand mal convulsion 10 min after the bite which was shortly after removal of a compression bandage. A severe coagulopathy of the defibrination type required administration of five ampoules of brown snake monovalent antivenom (CSL). The association of envenomation by snakes and convulsions is discussed, as is the management of severe defibrination due to envenomation.

Animals↗
PubMed1989

Resistance within the therapeutic community.

Resistance can take many forms. It may be subtle or more apparent. Resistance can be overcome more easily in a group compared with individual therapy. The author outlines some common forms of resistance, presents some basic principles for managing resistance, and provides clinical examples of resistance and its management in a therapeutic community.

Adult↗
PubMed1989

Primary hyperparathyroidism.

Primary hyperparathyroidism is a pathological entity due to excessive secretion of parathormone from a single or multiple parathyroid glands. The biochemical hallmark of this disorder is an elevated serum calcium. The relationship of the parathyroid glands with the thymus gland in fetal development accounts for the occasional aberrant location of the parathyroids. By utilizing computed tomography or nuclear scanning or both preoperatively, the surgeon can isolate the hyperfunctioning adenoma and resect it, thus minimizing potential complications.

Humans↗
PubMed1988

Rearrangement of IgH genes in normal thymocyte development.

IgH chain gene segments are rearranged in 30 to 50% of peripheral T cells. We have analyzed IgH gene rearrangements during normal T cell development, using a well characterized collection of hybridomas derived from fetal, newborn, adult, or aged thymocytes. Our results show that IgH rearrangements occur in the thymus after T cell receptor gene and T cell specific gamma-gene rearrangements but before thymocyte maturation is completed. Therefore IgH gene rearrangements occur at an intermediate stage in thymocyte development. This may be of significance in delineating human lymphoid leukemias. Not all thymocyte hybridomas carried IgH gene rearrangements. Age-related shifts in frequencies of cells with IgH gene rearrangements, probably indicating changes in the composition of thymocyte populations, were found. Finally, a detailed analysis of D to J joins revealed an ordered progression of partial rearrangements at the IgH locus, whereby the most proximal DH-segment, DQ52, is used predominantly at early stages, but that other D to J rearrangements at the same locus may occur subsequently.

Animals↗
PubMed1988

Self-tolerance eliminates T cells specific for Mls-modified products of the major histocompatibility complex.

In mice the product of the Mlsa locus is an unusual antigen capable of interaction with certain products of the major histocompatibility locus (MHC) to form a ligand for a large portion of the T-cell alpha/beta receptor repertoire, including nearly all receptors that use V beta 8.1. The presence of Mlsa/MHC during T-cell development results in the deletion of T cells that express V beta 8.1, documenting the importance of clonal deletion in establishing tolerance to self antigens.

Animals↗
PubMed1988

Experimental Rift Valley fever in rhesus macaques.

Rift Valley fever (RVF) is a major cause of human morbidity and mortality in endemic areas of sub-Saharan Africa and has the potential to cause epidemic disease in receptive areas world-wide. In this study, a RVF viral isolate from the 1977 Egyptian epidemic (ZH-501) inoculated intravenously into rhesus macaques caused a benign viremic infection in most, but resulted in the hemorrhagic fever syndrome in 20 per cent (3 of 15). Serious disease of this type has not previously been observed in nonhuman primates inoculated with RVF virus and may be a consequence of the viral strain used or the route of inoculation. Severe disease was accompanied by extensive liver necrosis, disseminated intravascular coagulation, and microangiopathic hemolytic anemia. We also attempted to prevent RVF by passive transfer of serum from vaccinated rhesus monkeys (plaque-reduction neutralization test titer 1:2,560). As little as 0.025 ml/kg prevented the development of viremia in naive rhesus monkeys after subcutaneous inoculation of virus. The monkey model should be helpful in understanding the pathogenesis and prevention of human RVF.

Animals↗
PubMed1988

Variation in venom proteins from isolated populations of tiger snakes (Notechis ater niger, N. scutatus) in South Australia.

Pooled venom of peninsula tiger snakes (Notechis ater niger) from 11 insular populations and one mainland area, and from a single population of the mainland tiger snake (N. scutatus) were subjected to SDS-PAGE and gel filtration chromatography. At least 20 proteins were resolved in the SDS-PAGE, some of which were common to all populations, but many others were highly variable. Elution profiles produced through gel filtration showed a clustering of some populations with like profiles, while others had distinctive patterns. Similarities and dissimilarities between each population venom profile were appraised. Variation in the venom patterns was independent of prey type or local ecology. Statistical analysis of the SDS-PAGE banding patterns suggests that grouping of populations was dependent on their relative geographic position and the time of isolation of each population from one another and the mainland population.

Animals↗
PubMed1988

Efficacy of continuous treatment with astemizole (Hismanal) and terfenadine (Seldane) in ragweed pollen-induced rhinoconjunctivitis.

Astemizole (Hismanal; Janssen Pharmaceutica Inc., Mississauga, Ontario, Canada) and terfenadine (Seldane; Merrell Dow Pharmaceuticals [Canada], Inc., Concord, Ontario, Canada) were compared for clinical efficacy in a double-blind randomized trial during the ragweed pollen season. Sixty adults, with a history of ragweed-induced rhinoconjunctivitis, were matched according to sensitivity to ragweed pollen. Half took astemizole, 10 mg/day, and the rest took terfenadine, 60 mg twice daily. Medications were started 1 week before and continued daily until 1 week after the ragweed pollen season (7 weeks). If the trial medication was insufficient to keep symptoms well controlled, a steroid nasal spray and/or eye drops were used in the minimum dose that would ensure symptoms were not troublesome. Subjects completed a diary of nocturnal and daytime nasal and eye symptoms and recorded the amount of concomitant medications used. Astemizole showed greater efficacy than terfenadine in controlling rhinorrhea; in addition, the astemizole group used less nasal spray. Other nasal symptoms, eye symptoms, and use of eye drops were similar in the two groups. Skin test sensitivity to serial dilutions of histamine and ragweed extract was determined 1 and 7 weeks after the start of the trial medication. More tachyphylaxis to histamine was shown by the subjects taking terfenadine, as demonstrated by a larger increase in skin sensitivity over the study period. However, a similar change was not observed for ragweed skin sensitivity. These results suggest that when the medication is started before and continued daily throughout the pollen season, astemizole is more efficacious than terfenadine in controlling nasal symptoms, but there is little difference for eye symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

A T cell receptor V beta segment that imparts reactivity to a class II major histocompatibility complex product.

We have identified in mice an allele of a new T cell receptor V beta gene, V beta 17a, whose product is bound by the monoclonal antibody KJ23a. Over 90% of T cell hybridomas prepared from V beta 17a+ T cells of SWR mice respond to allogeneic forms of the IE class II MHC protein, indicating that V beta 17a has an appreciable affinity for IE regardless of the other components of the T cell receptor. These results suggest a bias in the germ-line T cell receptor repertoire toward recognition of MHC proteins and indicate that the V beta portion of the receptor may form the most important contact points with MHC ligands.

Animals↗
PubMed1987

Expression and role of the T cell receptor in early thymocyte differentiation in vitro.

Fetal thymus organ culture was used to study the expression and function of antigen-specific, major histocompatibility complex-restricted receptors on thymocytes. Receptor gene rearrangement and expression occurred de novo in organ culture indicating that these events are induced in the thymus itself, presumably in response to thymus-derived stimuli. During organ culture a population of immature thymocytes expressing low levels of receptors developed first, and then diminished as mature thymocytes with high levels of receptor expression appeared. Continuous culture with antireceptor antibody modulated receptor from the surfaces of immature thymocytes, but did not prevent their appearance or accumulation. By contrast, appearance of receptor-bearing mature thymocytes was prevented in the presence of antireceptor antibody. These results indicate that the receptor is not essential for the generation of immature thymocytes but is involved in the selection or maintenance of mature cells from this pool.

Animals↗
PubMed1987

The nervus terminalis of the shark: the effect of efferent impulses on ganglion cell activity.

Tonic activity was recorded extracellularly in the nervus terminalis of the bonnethead shark. Cutting or cooling the nerve central to its ganglion eliminated these spikes, and was followed by an increase in multi-unit activity which appeared to arise from the ganglion. After cutting centrally, electrical stimulation of the distal stump of the nerve suppressed this multi-unit activity. The data suggest that efferent impulses may normally suppress ganglion cell activity.

Action Potentials↗