Decreased apoptosis despite severe CD4 depletion in the thymus of a human immunodeficiency virus-1 infected child

Thymic epithelial space (TES), where thymopoiesis is located, and thymic perivascular space (PVS), where T lymphocytes are pooled, appear differentially involved in human immunodeficiency virus 1 (HIV-1)-infected children. The decline of CD4+ T cells during HIV-1 infection is probably due to a relative predominance of CD4+ T cell destruction on cell proliferation. Antiretroviral therapy (ART) typically increases circulating CD4+ T cell counts, but it is debated whether ART reduces the destruction of existing CD4+ T cells or enhances the production of new cells. We report on postmortem flow-cytometry, immunohistochemistry, and terminal deoxynucleotide transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) studies performed on thymus of an 11-year-old vertically HIV-1 infected child receiving ART. Thymus tissue sections showed that CD4+ and CD8+ cells were more numerous in PVS than in TES (p=0.0334 for CD4+ cells, p<0.0001 for CD8+ cells). Thymus cell suspension showed that CD4+ CD8+ cells (immature thymocytes) were 15.4% (age-related control: 80.5%). Very few apoptotic CD4+ cells were seen in TES. Very low to absent proliferation activity was demonstrated in both TES and PVS. We suggest that 1) lymphocyte depletion in HIV-1 infection is more pronounced in TES than in PVS, 2) immature thymocytes are not enhanced, and 3) an anti-apoptotic effect in the thymus seems to be a potential ART mechanism to explain the CD4+ pool increase.

Comparing angiographic coronary revascularization strategies: a 'natural' experiment

OBJECTIVE

To study the impact of intracoronary stents on clinical restenosis in the 'real world'.

DESIGN

Retrospective comparison of the rates of clinical restenosis between two cohorts exposed to different strategies for percutaneous transcatheter intervention. The endpoint was the first of death, myocardial infarction, coronary artery bypass grafting, repeat percutaneous transluminal coronary angioplasty (PTCA) or repeat coronary angiography within nine months.

SETTING

Tertiary care cardiac referral centre serving a large, metropolitan population.

PATIENTS

Patients undergoing angiographic revascularization from January 1 to February 28, 1996 (the 'restricted' group [R], n=147) were compared with a before and after cohort (the 'usual' group [U], n=232, divided into those who underwent revascularization between November 1 and November 30, 1995, and those who underwent revascularization between April 1 and May 31, 1996).

INTERVENTIONS

The R group was revascularized during a period of economic constraint, which imposed a shortage on stent availability. The U cohort underwent revascularization before and after the shortage (an 'unrestricted' environment for stent usage).

MAIN RESULTS

There was no difference in clinical restenosis rates between the R (34.7%) and U (37.9%) groups (P=0.524, OR R/U=0.915, 95% CI 0.694 to 1.206). Also, the rate of clinical restenosis was the same among patients who underwent PTCA without stent insertion (34.8%) and those who received a stent (39.4%) (P=0.368, OR=1.13, 95% CI 0.87 to 1.44).

CONCLUSIONS

At the authors' institution, a restricted stenting policy did not result in a higher clinical restenosis rate than that of usual practice.

Predictors of same-admission cardiac catheterization in patients with acute ischemic syndromes

BACKGROUND

Various strategies exist for the use of cardiac catheterization in unstable angina or non-Q wave myocardial infarction. At the authors' institution, the overall volume of cardiac catheterization has increased in recent years.

OBJECTIVE

To investigate whether this increased volume of cardiac catheterization was due to adoption of a more invasive approach to the management of patients with acute ischemic syndromes.

DESIGN

A retrospective cohort study was conducted using detailed chart review of coronary care unit admissions during 1990/91 and 1993/94.

SETTING

A university-affiliated tertiary care referral centre with facilities for cardiac catheterization.

PATIENTS

One hundred patients randomly selected from among those with unstable angina, non-Q wave myocardial infarction or chest pain not yet diagnosed in each of the study years. Detailed follow-up was complete for all patients.

OUTCOME MEASURE

The use of cardiac catheterization during the index admission was documented.

MAIN RESULTS

There was a trend towards more frequent use of same admission cardiac catheterization in the later period (21% [CI 14% to 31%] versus 12% [CI 7% to 20%], P = 0.09). However, after controlling for baseline characteristics and in-hospital events, the year of admission did not independently predict the use of catheterization (P = 0.60). By multivariate logistic regression, recurrence of chest pain and evidence of myocardial necrosis were most closely associated with same-admission cardiac catheterization.

CONCLUSIONS

Although clinical factors partially explain the increased use of catheterization over time, there may have also been shift towards a more aggressive practice style at the authors' institution. Further study is needed to address this possibility.

Anisotropic scatter patterns and anomalous birefringence of obliquely deposited cerium oxide films

Cerium oxide films formed by electron-beam evaporation onto oblique substrates are shown to scatter light strongly into spatially anisotropic distributions and to exhibit large normal-incidence birefringence Δ n = n(s) - n(p). The apparatus for direct recording of a useful projection of the scatter distributions is described. Characteristic differences in scatter patterns recorded for cerium oxide, relative to those from tilted columnar titania and zirconia films, are believed to be associated with unusual microstructures recorded for cerium oxide films by scanning electron microscopy. With increasing angle of deposition, the microstructure of cerium oxide was observed to change from densely packed columns to partially isolated needlelike columns at angles that do not obey the tangent rule. In particular, deposition at 55° yielded columns nearly perpendicular to the substrate, yet the normal-incidence birefringence was large. The retardation of the films was recorded as a function of angle of incidence for propagation in the deposition plane. A turning point near 0° incidence for the 55° film confirmed that one principal axis is perpendicular to the substrate. Significant bunching of columns into rows running perpendicular to the deposition plane was recorded by scanning electron microscopy and may account for both the scatter and the birefringence.

Modal contours for biaxial thin-film waveguides

The modal characteristics of a general tilted columnar biaxial thin-film waveguide are displayed by the plots of both Snell's law quantity β = n sin θ and the polarization of the evanescent field at the cover interface on a polar diagram. The association of characteristic features in the modal diagram with the basis fields is demonstrated, and the mechanism that allows p and s modes propagating in the deposition plane to overlap, without the modal contours crossing, is explored.

Relation between light scattering and the microstructure of optical thin films

Special substrate-film designs are used to measure roughness-induced scattering and scattering from the volume of optical thin films separately. So theoretical models of surface roughness and volume scattering become applicable to the experimental data, and quantitative information on thin-film microstructure can be derived. Measuring total integrated and angle-resolved scattering on oxide, fluoride, and chalcogenide films of different film thicknesses yields the evolution law of microstructural growth, which for the majority of investigated films roughly follows a square-root dependence on film thickness. Packing densities of fluoride films calculated from volume-scattering data are found to agree with results from quartz-crystal monitoring.

Light scattering from the volume of optical thin films: theory and experiment

A theoretical model is presented that describes the volume scattering in thin optical films, particularly in typical columnar structures. It is based on a first-order perturbation theory that concerns the fluctuation of the dielectric permittivity in the film. For evaporated PbF(2) films that show a pronounced columnar morphology, angular as well as total integrated scattering measurements at lambda = 633 nm have been performed on a special layer design to suppress roughness-induced scattering. A comparison of the predicted theoretical and the measured experimental values leads to such structural parameters as packing density and the evolutionary exponent of the columns.

[Acute myeloblastosis in von Jaksch-Luzet syndrome]

A 7 month-old infant of Italian origin, who was given a vitamin-D deficient diet developed a Von Jaksch-Luzet syndrome with more than 20% myeloblasts in the bone marrow. Plasma levels of vitamin D metabolites wer low and parathormone levels were high. A low dose of vitamin D3 (2,000 IU cholecalciferol/day) resulted in the recovery of a normal phosphocalcic balance and in the disappearance of myeloblastosis.

Shigella and shigellaemia

Two cases of bacteraemia with Shigella flexneri 2a in children are described. They illustrate the wide variety of clinical manifestations of shigellosis, ranging from benign gastroenteritis to septicaemia associated with severe extra-intestinal manifestations.