Central venous catheters in patients with AIDS

Central venous catheters (CVCs) for patients with AIDS are at risk of a number of complications including bacterial infections. A 6-year retrospective review was undertaken of the records of the 33 patients (42% infected by injection drug use (IDU)) who received intravenous therapy both in hospital and at home via CVCs. Twenty-eight per cent of 53 insertions suffered a complication, the commonest of which was a pneumothorax (8%). The post insertion complication rate was 0.98/100 catheter days (cd). Thrombotic occlusion (0.15/100 cd) was the commonest non septic event while sepsis was overall the commonest event (0.69/ 100 cd) of which half were considered serious (0.33/100 cd). The most frequently isolated organisms were Staphylococci spp. (71%). The median time to an exit site infection was 59 days and to serious catheter sepsis 86 days. Infection did not differ significantly with age, gender, transmission risk activity or catheter type although Portacaths had the lowest rate of infection (0.33/100 cd). The median survival of the 53 CVCs was 88 days although if the temporary catheters were excluded it was 118 days. Kaplan-Meier estimates of survival analysis revealed 55%, 32% and 19% of all the CVCs surviving 3, 6 and 12 months respectively. Our experience suggests that home intravenous therapy and previous IDU does not preclude the use of CVCs although further research is needed on reducing the infection-related complications of such therapy.     

The protective effects of ipratropium bromide and terbutaline on distilled water-induced bronchoconstriction

Subarachnoid hemorrhage (SAH) was produced in rabbits by four subarachnoid injections of blood (n = 7) or saline (n = 6); a control group (n = 6) had no injections. Basilar artery vasospasm was assessed by serial angiograms. Resting CBF (microspheres) and CBF reactivity to hypercapnia (65 and 85 mm Hg) and hypoxia (fractions of inspired oxygen of 0.15 and 0.10) were determined. Basilar artery vasospasm was seen with SAH. Resting CBF was reduced by 31% (SAH 43 +/- 12, saline 65 +/- 17, control 60 +/- 21 ml 100 g-1 min-1), and resting cerebrovascular resistance was increased (SAH 1.84 +/- 0.30, saline 1.31 +/- 0.49, control 1.39 +/- 0.25 mm Hg ml-1 100 g-1 min-1) after SAH. CBF rose to a similar degree in all three groups in response to hypercarbia and hypoxia. We conclude that resting CBF is reduced in this model of SAH, but vascular reactivity remains intact.     

Field evaluation of the NOVA Celltrak 12 hematology analyzer

An evaluation of the NOVA Celltrak 12 was performed over a 6-week period. Precision, linearity, carryover, and reproducibility of values compared favorably to manufacturers' claims. The correlation was performed using the Coulter S Plus VI as the reference instrument and yielded coefficients of correlation for measured parameters of greater than .98 with the exception of RDW at r = .84, MCV at r = 0.96, and MPV at r = .92. Three-part differential information and an expanded flagging system affords increased clinical information and trouble-shooting guides. The three-part differential information compared favorably with that of the Coulter S Plus VI with lymphocyte percentage r = .96, granulocyte percentage r = .94, and monocyte percentage r = .50. We conclude that this instrument performed well in a clinical setting.     

Specific requirement for CD3epsilon in T cell development

T cell antigen receptor (TCR) and pre-TCR complexes are composed of clonotypic heterodimers in association with dimers of signal transducing invariant subunits (CD3gamma, -delta, -epsilon, and zeta). The role of individual invariant subunits in T cell development has been investigated by generating gene-specific mutations in mice. Mutation of CD3gamma, -delta, or zeta results in an incomplete block in development, characterized by reduced numbers of mature T cells that express low levels of TCR. In contrast, mature T cells are absent from CD3epsilon-/- mice, and thymocyte development is arrested at the early CD4(-)CD8(-) stage. Although these results suggest that CD3epsilon is essential for pre-TCR and TCR expression/function, their interpretation is complicated by the fact that expression of the CD3gamma and CD3delta genes also is reduced in CD3epsilon-/- mice. Thus, it is unclear whether the phenotype of CD3epsilon-/- mice reflects the collective effects of CD3gamma, -delta, and -epsilon deficiency. By removing the selectable marker (PGK-NEO) from the targeted CD3epsilon gene via Cre/loxP-mediated recombination, we generated mice that lack CD3epsilon yet retain normal expression of the closely linked CD3gamma and CD3delta genes. These (CD3epsilonDelta/Delta) mice exhibited an early arrest in T cell development, similar to that of CD3epsilon-/- mice. Moreover, the developmental defect could be rescued by expression of a CD3epsilon transgene. These results identify an essential role for CD3epsilon in T cell development not shared by the CD3gamma, CD3delta, or zeta-family proteins and provide further evidence that PGK-NEO can influence the expression of genes in its proximity.     

Adhesion to laminin is down-regulated upon retinoic acid-induced F9 cell differentiation: a role for alpha 6/beta 1 integrin

F9 mouse teratocarcinoma cells have a high capacity to adhere to laminin and we identified alpha 6/beta 1 integrin as the principal laminin-binding protein present in these cells. F9 cells differentiated into parietal endoderm when monolayer cultures were treated with retinoic acid and dibutyryl cyclic AMP. In this process a decreased adherence to laminin was observed due to a lower expression of alpha 6/beta 1 integrin on the cell surface.     

The matrix effects on kinetic rate constants of antibody-antigen interactions reflect solvent viscosity

This study describes the influence of different matrices on two model antibody-antigen interactions; that between beta2microglobulin and anti beta2microglobulin, and that of rabbit anti mouse Fc fragment (RAMFc) with mouse IgG. The matrices investigated were; phosphate-buffered saline pH 7.4 containing 0.05% Tween 20 detergent, horse serum, a 50:50 mixture of phosphate-buffered saline/Tween 20 and horse serum, and four glycerol solutions of differing concentrations. A recently developed optical biosensor, the IAsys, was used to monitor the interactions in real-time and provide precise determinations of k(ass), k(diss) and KA values. The results show that the rates of association and dissociation for the two different antibody:antigen models are significantly affected by the surrounding matrix. Glycerol of known viscosity was used as a matrix in both models to show that this effect is attributable to the viscosity as opposed to proteins present in the matrix. The viscosity of the matrix has also been shown to have an apparent influence upon the overall equilibrium/affinity constant for the interaction, with measurements of KA tending to increase with viscosity. The significant effects of matrix on kinetic rate constants for antibody-antigen interactions shown here have important implications in the use of immunoassays where non-equilibrium measurements are made in serum matrices.