A soluble factor produced by macrophages mediates the neurotoxic effects of HIV-1 Tat in vitro.

OBJECTIVES: There is now a strong consensus that the neurotoxic properties of HIV-1 are likely to be mediated by an indirect mechanism in which neurones are damaged by infected mononuclear cells. The aim of this study was to determine the ability of HIV-1 Tat to induce neurotoxic properties in a murine macrophage cell line RAW264.7. DESIGN: Simple culture systems using dissociated neurones may not provide the appropriate microenvironment in which to observe the complex cell-cell interactions that occur in the brain. We have therefore developed a more physiological model in which rat organotypic hippocampal slices are co-cultured with the murine macrophage cell line RAW264.7. Effects of Tat were studied by using a stable Tat expressing RAW264.7 cell line or by addition of recombinant Tat protein to co-cultures. METHODS: Organotypic hippocampal slices prepared from 8-10 day rat pups were grown on membrane inserts that were placed into six-well plates on which RAW264.7 cells were growing as an adherent monolayer. Cell death in the slices was assessed using propidium iodide. Specific astrocytic (glial fibrillary acidophilic protein; GFAP) and neuronal (microtubule-associated protein; MAP2) markers were visualized by immunocytochemistry. RESULTS: RAW264.7 cells that either expressed or were exposed to HIV-1 Tat protein, produced a soluble factor that caused profound degeneration in brain slice cultures involving loss of both glial cells and neurones. By contrast treatment of slice cultures with Tat in the absence of RAW264.7 cells was not neurotoxic. CONCLUSIONS: The neurotoxic properties previously attributed to HIV-1 Tat are likely to be mediated via induction of macrophage derived soluble factor(s).     

Semipermeable dressing and transepidermal water loss in premature infants

Within the first days of life, 10 infants, of 32 weeks' gestational age or less, began 2 weeks of treatment with a semipermeable wound dressing over a small area of skin. The effects of the dressing on transepidermal water loss and cutaneous microflora were evaluated. Transepidermal water loss from the semipermeable dressing-treated skin was significantly less than that from the untreated skin immediately after placement of the dressing (8.1 +/- 1.8 g/m2.h-1 vs 17.7 +/- 3.5 g/m2.h-1, P less than .0001). The normal accelerated skin maturation process that occurs in these infants continued beneath the semipermeable dressing. The number of gram-negative bacilli or other bacteria did not increase beneath the semipermeable dressing beyond that seen on the untreated site. Malassezia furfur was found only on the control site, never beneath the semipermeable dressing. According to results of this preliminary study, a semipermeable dressing can be safely used in premature infants and the use of a semipermeable dressing may decrease the excessive transepidermal water loss associated with prematurity.     

Phospholipase production in morphological variants of Candida, albicans

The yeast Candida albicans is considered a dangerous opportunist in a compromised host. Both phases of growth are thought to be pathogenic, however, evidence suggests that the hyphal phase is the more virulent. It has been proposed that the increased virulence lies in the ability of hyphae to digest and penetrate host tissue, thus enabling access of fungal cells to the deeper tissues. However, this one characteristic does not sufficiently explain the organism's success as a pathogen. Recently, high-frequency, colonial morphology switching systems were described in C. albicans. We obtained some of these variants and tested them for the ability to produce extracellular phospholipase(s), a generally accepted mechanism of pathogenesis in many microorganisms. Using egg yolk agar plates, we showed that all variants produced the enzyme. However, one produced significantly more than the others.     

Oestriol with oestradiol verses oestradiol alone: a comparison of endometrial, symptomatic and psychological effects

In a prospective, double-blind, randomized, cross-over trial, the effects of oral oestradiol, 2 mg daily, on the endometrial histology, frequency and severity of vaginal bleeding, and the symptomatic and psychological status of postmenopausal women were compared with those of oral oestradiol, 2 mg daily, plus oestriol, 1 mg daily. Both therapies were prescribed for 3 months on a cyclical basis. The addition of oestriol to oestradiol did not modify the endometrial response. The prevalence of proliferative/hyperplastic endometrium (64%: 9 of 14 biopsies) was similar after both treatments and there were no significant differences in either the frequency or heaviness of vaginal bleeding. Both therapies significantly reduced hot flushes, night sweats and vaginal dryness: no significant differences in effect on the symptomatic and psychological status were recorded. The addition of 1 mg of oestriol to 2 mg of oestradiol did not confer any benefit and the value of such an addition is challenged.     

The effects of the anti-tumor agent mezerein on the cytotoxic capacity and oxidative metabolism of human blood cells

Summary Mezerein, the most active antitumor compound isolated from the daphne species of plants, has a structural similarity to phorbol myristate acetate (PMA), the major active compound isolated from croton oil. PMA is known to have tumor promoting activity and is a potent inflammatory agent. Mezerein has similarly been reported to have potent inflammatory properties but appears to be a weaker tumor promoter than PMA. While the effect of PMA on the function and metabolism of human blood cells has been extensively studied, there is little similar information concerning mezerein. Therefore, in these studies, we have compared the capacities of mezerein and PMA to activate the cytotoxic capacity and oxidative metabolism of human granulocyte (PMNs), monocyte, lymphocyte, and mononuclear cell (lymphocytes and monocytes) cultures in vitro. Mezerein stimulated the oxidative metabolism of PMNs in an identical manner to PMA as indicated by a burst in the activity of the HMPS pathway, the production of H₂O₂, hydroxyl radical and stable oxidants. Mezerein also stimulated the release of thromboxane B₂ from PMNs. Both compounds activated the oxidative metabolism of monocytes but not the oxidative metabolism of lymphocytes. The enhanced oxidative metabolism of the phagocytic cells was associated with an increased cytotoxicity against human red cells which are sensitive to oxidant damage but not against the NK resistant Raji lymphoblast cell line or the SW1116 colon tumor cell line.Of interest is that mezerein did not augment significantly the minimal cytotoxic capacity (NK activity) of mononuclear cells, monocytes or freshly isolated lymphocyte cultures against the tumor cell targets used in our experiments. However, lymphocyte cultures preincubated for 15 hours with mezerein had a marked enhancement of cytotoxicity against the tumor targets. This activation was not observed in similarly treated mononuclear cell cultures suggesting a suppressor activity of the monocytes.Our data suggest that the potent inflammatory activity of mezerein similar to PMA, may be related to its capacity to activate the oxidative and arachidonic metabolism of phagocytic cells. In addition, the capacity of mezerein to activate the cytotoxic capacity of lymphocytes may relate to its reported in vivo antitumor activity.Dr. Barton is currently a resident in Medicine at the Unviersity of Chicago.     

Alcohol after midazolam sedation: does it really matter?

Patients who arrive home several hours after ambulatory surgery may drink alcohol. The extent to which the residual effects of drugs used in ambulatory surgery interact with alcohol, perhaps potentiating alcohol effects, is not known. Accordingly, the purpose of this study was to determine whether intravenous midazolam had residual effects that would interact with alcohol consumed 4 h after the midazolam injection. Healthy male volunteers (n = 16) participated in a double-blind, randomized, placebo-controlled crossover trial. Subjects were studied four times successively with 1 wk between trials. On each test day the subjects randomly received by slow intravenous injection (30 s) either saline or 0.1 mg/kg of midazolam. Four hours after injection, the subjects consumed a beverage that either did or did not contain 0.7 g/kg of alcohol. Before and 1, 3, 5, and 7 h after injection (and before and 1 and 3 h after beverage consumption), psychomotor performance and mood were assessed. Whereas both midazolam and alcohol alone had effects on the dependent measures in this study, there were no significant interactions between the two drugs (i.e., potentiation of alcohol effects by midazolam or potentiation of midazolam by alcohol). We conclude that the effects of a short-acting benzodiazepine used in ambulatory surgery have probably dissipated by the time a patient arrives home, and that effects from alcohol ingested at home will probably not be influenced by the recent administration of a short-acting benzodiazepine such as midazolam.     

Effect of inborn versus outborn delivery on clinical outcomes in ventilated preterm neonates: secondary results from the NEOPAIN trial.

OBJECTIVE: The objective of this study was to evaluate the effect of birth center (inborn versus outborn) on morbidity and mortality for preterm neonates (23 to 32 weeks) using data collected prospectively within a uniform protocol. STUDY DESIGN: Secondary analyses of data from the NEurologic Outcomes and Pre-emptive Analgesia In Neonates (NEOPAIN) trial (n=898) were performed to evaluate the effect of inborn versus outborn delivery on neonatal outcomes, including the occurrence of severe intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), chronic lung disease (CLD), and mortality. RESULTS: Outborn babies were more likely to have severe IVH (p=0.0005); this increased risk persisted after controlling for severity of illness. When adjustments for antenatal steroids were added, the effect of birth center was no longer significant. Neither the occurrences of PVL or CLD nor mortality were significantly different between the inborn and outborn infants. CONCLUSION: Outborn babies are more likely to have severe IVH than inborn babies, perhaps because their mothers are less likely to receive antenatal steroids. Improvements in antenatal steroid administration to high-risk women may substantially reduce neonatal morbidity.