Natural killer (NK) cell-mediated cytotoxicity: differential use of TRAIL and Fas ligand by immature and mature primary human NK cells

Mature natural killer (NK) cells use Ca2+-dependent granule exocytosis and release of cytotoxic proteins, Fas ligand (FasL), and membrane-bound or secreted cytokines (tumor necrosis factor [TNF]-alpha) to induce target cell death. Fas belongs to the TNF receptor family of molecules, containing a conserved intracytoplasmic "death domain" that indirectly activates the caspase enzymatic cascade and ultimately apoptotic mechanisms in numerous cell types. Two additional members of this family, DR4 and DR5, transduce apoptotic signals upon binding soluble TNF-related apoptosis-inducing ligand (TRAIL) that, like FasL, belongs to the growing TNF family of molecules. Here, we report that TRAIL produced or expressed by different populations of primary human NK cells is functional, and represents a marker of differentiation or activation of these, and possibly other, cytotoxic leukocytes. During differentiation NK cells, sequentially and differentially, use distinct members of the TNF family or granule exocytosis to mediate target cell death. Phenotypically immature CD161(+)/CD56(-) NK cells mediate TRAIL-dependent but not FasL- or granule release-dependent cytotoxicity, whereas mature CD56(+) NK cells mediate the latter two.     

On the influence of porosity on the portevin-le chatelier effect in sintered iron

Sintered irons of four different porosities were strained in tension at temperatures between 295 (room temperature) and 873 K. Serrated stress-strain curves and high work hardening in the temperature range from 333 to 693 K, for all porosities, were characteristic of dynamic strain aging. The activation energy for the onset of serration was ±0.82 eV and was independent of porosity. On the contrary, the parameter β from the relation for dislocation density increased with increasing porosity.     

Certificate-of-need deregulation and indigent hospital care

For almost twenty years certificate-of-need (CON) regulations have protected existing hospitals from unrestricted competition in services. Although the explicit purpose of CON regulation was to prevent hospitals from duplicating services and investing in costly excess capacity, it has been unsuccessful in accomplishing this goal. On the other hand, CON policies have, we suggest, been pursued with the implicit aim of "cross subsidization," that is, regulators have used their power to issue licenses and restrict competition in order to create an incentive to hospitals to provide high levels of care to the indigent population. Posner (1971) has noted that to achieve cross subsidization, entry into lucrative services must be restricted. We present evidence that CON licenses have been used to promote the internal subsidization of indigent care in probit analysis, based on data from Florida spanning the period 1983-89. While this method of financing indigent care may be preferred by legislators who do not want to face the political consequences of raising taxes to pay for the service, it has troubling implications for the hospital provision of indigent care, especially in an era of CON deregulation.     

Incontinence and vesical neck strictures following radical retropubic prostatectomy

OBJECTIVES: To evaluate the incidence and severity of vesical neck strictures and urinary incontinence after radical retropubic prostatectomy (RRP) for prostate cancer. METHODS: Between August 1983 and December 1991, 481 consecutive patients underwent RRP by 1 of 2 senior surgeons. Strictures were treated by passing a urethral sound. Incontinence was measured by asking patients for a daily "pad count" of pads required to control urinary leakage. Results were compared to patient age, tumor volume, number of neurovascular bundles spared, preoperative urinary complaints, and previous transurethral resection of the prostate. RESULTS: Of 456 patients with adequate follow-up to determine stricture formation, 82.5% had no strictures, 6.8% required a single dilation, 3.7% required 2 dilations, 3.1% required 3 dilations, and 3.9% required more than 3 dilations. Risk of stricture formation was unrelated to every variable studied. Of 458 patients with adequate follow-up to determine recovery of continence, 80.1% required no pads, 8.1% required 1 to 2 pads a day, 6.6% required 3 to 5 pads a day, and 5.2% were totally incontinent 1 year or more after surgery. Incontinence was closely associated with postoperative urinary urgency. CONCLUSIONS: Strictures are a common but easily managed complication of RRP for prostate cancer. Despite substantial surgical experience, we report a somewhat higher rate of postoperative incontinence than other recently reported series. Our experience is more closely matched by published surveys of patient-reported complications after RRP.     

Genetic analysis of tissue interactions required for otic placode induction in the zebrafish

Development of the vertebrate inner ear begins during gastrulation with induction of the otic placode. Several embryonic tissues, including cephalic mesendoderm, notochord, and hindbrain, have been implicated as potential sources of otic-inducing signals. However, the relative contributions of these tissues have not been determined, nor have any genes affecting placode induction been identified. To address these issues, we analyzed otic placode induction in zebrafish mutants that are deficient in prospective otic-inducing tissues. Otic development was monitored by examining mutant embryos for morphological changes and, in some cases, by visualizing expression patterns of dlx-3 or pax-2.1 in preotic cells several hours before otic placode formation. In cyclops (cyc-) mutants, which develop with a partial deficiency of prechordal mesendoderm, otic induction is delayed by up to 1 h. In one-eyed pinhead (oep-) mutants, which are more completely deficient in prechordal mesendoderm, otic induction is delayed by 1.5 h, and morphology of the otic vesicles is abnormal. Expression of marker genes in other regions of the neural plate is normal, suggesting that ablation of prechordal mesendoderm selectively inhibits otic induction. In contrast, the timing and morphology of otic development is not affected by mutations in no tail (ntl) or floating head (flh), which prevent notochord differentiation. Similarly, a mutation in valentino (val), which blocks early differentiation of rhombomeres 5 and 6 in the hindbrain, does not delay otic induction, although subsequent patterning of the otic vesicle is impaired. To test whether inductive signals from one tissue can compensate for loss of another, we generated double or triple mutants with various combinations of the above mutations. In none of the multiple mutants do the flh or val mutations exacerbate delays in placode induction, although val does contribute additively to defects in subsequent patterning of the otic vesicle. In contrast, mutants homozygous for both oep and ntl, which interact synergistically to disrupt differentiation of cephalic and axial mesendoderm, show a delay in otic development of about 3 h. These data suggest that cephalic mesendoderm, including prechordal mesendoderm and anterior paraxial mesendoderm, provides the first otic-inducing signals during gastrulation, whereas chordamesoderm plays no discernible role in this process. Because val- mutants are deficient for only a portion of the hindbrain, we cannot rule out a role for that tissue in otic placode induction. However, if the hindbrain does provide otic-inducing signals, they apparently differ quantitatively or qualitatively from the signals required for vesicle patterning, as val disrupts only the latter.     

Brief note: Differences in intracellular localization of corn stunt spiroplasmas in magnesium treated maize.

Maize plants infected with Spiroplasma kunkelii show symptoms similar to that of plants in a magnesium-deficient soil, and it has been shown that the spiroplasma alters the plants’ magnesium absorption. In the current study we compared changes associated to either spiroplasma infection, two soil magnesium levels and their combinations. Plant symptoms were recorded and correlated with transmission electron microscopy observations. Plants grown on a high magnesium treatment showed no macroscopical alterations nor organelle ultrastructural alterations, while plants on a low magnesium treatment showed macroscopical vein yellowing and, ultrastructurally, they had most chloroplasts and mitochondrial membranes altered. Infected plants on a low magnesium treatment had an ageing aspect, ultrastructurally showed chloroplasts and mitochondrial alterations similar to those non-infected and grown on a low magnesium treatment, and spiroplasma cells were found in phloem cells, but outside their cytoplasm. Infected plants on a high magnesium treatment showed similar symptoms and ultrastructural alterations as either non-infected plants on the low magnesium treatment or in infected plants on the low magnesium treatment, but differ from them in that the spiroplasma cells were located inside the cytoplasm. Results suggest that magnesium is involved in the plant-pathogen interaction.     

Membrane permeability characteristics of metaphase II mouse oocytes at various temperatures in the presence of Me2SO

Real bone tumors are rarely encountered in the daily routine of radiological practice. Therefore, for a general radiologist there is no need for a specialist knowledge on this field. However, he should be able to distinguish benign from malignant lesions in order to avoid unnecessary biopsies. A systematic approach towards osteolytic lesions, e.g. according to the classification of Lodwick, is mandatory. CT and MRI are indicated to clear up the anatomy in areas of superposition artefacts in conventional radiology and to determine the inner structure of a lesion, e.g. fatty tissue, liquid/solid. This paper highlights the advantages and disadvantages and the cost-effective use of the imaging modalities including scintigraphy in the diagnosis of bone tumors and tumor-like lesions. Guidelines for the management of bony lesions will be given in detail. The option and necessity for a specialist second opinion is emphasized.     

TNF-alpha opens a paracellular route for HIV-1 invasion across the blood-brain barrier

BACKGROUND: HIV-1 invades the central nervous system early after infection when macrophage infiltration of the brain is low but myelin pallor is suggestive of blood-brain-barrier damage. High-level plasma viremia is a likely source of brain infection. To understand the invasion route, we investigated virus penetration across in vitro models with contrasting paracellular permeability subjected to TNF-alpha. MATERIALS AND METHODS: Blood-brain-barrier models constructed with human brain microvascular endothelial cells, fetal astrocytes, and collagen I or fibronectin matrix responded in a dose-related fashion to cytokines and ligands modulating paracellular permeability and cell migration. Virus penetration was measured by infectious and quantitative HIV-1 RNA assays. Barrier permeability was determined using inulin or dextran. RESULTS: Cell-free HIV-1 was retained by the blood-brain barrier with close to 100% efficiency. TNF-alpha increased virus penetration by a paracellular route in a dose-dependent manner proportionately to basal permeability. Brain endothelial cells were the main barrier to HIV-1. HIV-1 with monocytes attracted monocyte migration into the brain chamber. CONCLUSIONS: Early after the infection, the blood-brain barrier protects the brain from HIV-1. Immune mediators, such as TNF-alpha, open a paracellular route for the virus into the brain. The virus and viral proteins stimulate brain microglia and macrophages to attract monocytes into the brain. Infiltrating macrophages cause progression of HIV-1 encephalitis.     

Effects of cocaine administration during early organogenesis on prenatal development and postnatal growth in mice

Cocaine use has been associated with adverse developmental effects in humans. However, clinical reports both confirm and deny an association between cocaine use and malformations. Similarly, differences in species and strain, as well as route and timing of cocaine administration, have added to the difficulties in determining the teratogenicity of cocaine in animal models. This study was undertaken to compare the effects of dose, route, and timing of cocaine administration in ICR mice during early organogenesis. A single intraperitoneal (ip) administration of cocaine ( > or = 60 mg/kg) on Day 9 of gestation (plug day = 1) produced maternal lethality. The predominant developmental effect of cocaine administration was an increase in the percentage of litters exhibiting an enlarged renal pelvis. Despite a high incidence of affected pups at these doses, the enlargement was not severe. These results, in agreement with previous reports, provide further evidence that the developing urogenital system is sensitive to cocaine administration. When cocaine was administered using a subcutaneous route, pup weights were greater and the incidence of enlarged renal pelvis was lower than when an ip route was used. To better mimic human binge cocaine abuse, the toxicity of a "split dose" was determined. A 60 mg/kg dose was administered using one administration of 60 mg/kg, two treatments of 30 mg/kg, or three administrations of 20 mg/kg with 1 hr separating the treatments. The incidence of enlarged renal pelvis was similar when cocaine was administered as one or two but was decreased when cocaine was administered as three treatments. Both the route and split-dose studies suggest that high-peak serum concentrations are required to perturb development. There were no differences in the incidence or severity of enlarged renal pelvis when cocaine was administered on Day 8, 9, or 10 or on all 3 days of gestation. This suggested that the increase in enlarged renal pelvis may not be a specific teratogenic effect of cocaine administration but may be a delay of normal development induced by cocaine exposure during this early period of organogenesis. To address this hypothesis, cocaine was administered on Day 9 using an ip route and the pups were allowed to be naturally born. In pups whose mothers received cocaine there was an increase in postnatal deaths and a trend toward a reduction in pup body weight/litter at Postnatal Day 21. However, when renal morphology was assessed on Postnatal Day 21 no abnormal kidneys were seen. This supports the hypothesis that enlarged renal pelvis produced by cocaine administration during early organogenesis represents a developmental delay and not a persistent teratogenic defect. These studies suggest that high peak cocaine concentrations are required to delay normal kidney morphogenesis in mice.