Acquisition of mature functional responsiveness in T cells: programming for function via signaling

The results discussed here provide strong evidence that different T-cell effector gene programs are activated by different signals, and that in several cases their responses to the same exogenous stimuli shift during the development and antigen responses of the cells. T-cell responses are thus conditional and plastic at the individual cell level. In the formalism of the introductory section, the results support elements of Models 2 and 3, and suggest a fusion between them as differentiation is explained in terms of alteration in the relative strengths of different intracellular signaling pathways. Returning to an initial question, how are different functional capabilities assigned nonrandomly to cells with different antigen recognition specificities? This question has not been answered, but it can be reformulated. If all virgin T cells can transiently make IL-2, then we must ask what features of cell biology explain the preferential preservation of IL-2 inducibility in CD4+ cells as opposed to CD8+ cells. If the capacity to induce IL-4 expression is not acquired in the thymus, then we may ask whether the initial opening of this locus depends on a CD4-transmitted signal. Similarly, the CD8 molecule itself might participate in inducing the initial differentiation events that render CTL-p inducible for granzyme C and perforin. This would be in accord with a large literature showing that CD8 engagement is much more important in the initial induction of CTL activity than in the exercise of function by pre-primed CTL effectors. The subtext of each of these "questions", however, is that intrathymic events may not directly affect the genes used by terminal effectors for function at all. They may instead bias a cell's complement of triggering receptors, thus rendering it differentially sensitive to particular signals generated during antigen reception. This view is extreme, and will probably turn out to be an overstatement. But it does inspire a unique set of investigations into the basis of T-cell function. It lends urgency to the question of whether CD4+ and CD8+ cells differ in their G proteins, kinases, or inducible proto-oncogenes. If they do, we can then ask whether such differences themselves arise in the periphery, or whether they can be traced back to thymocytes fresh from positive selection--or before.

Interleukin-1 synergy with phosphoinositide pathway agonists for induction of interleukin-2 gene expression: molecular basis of costimulation

The macrophage-derived cytokine interleukin-1 (IL-1) can provide a second signal with antigen to elicit production of interleukin-2 (IL-2) by helper T cells. The pathway(s) involved remains controversial, with protein kinase C and cyclic AMP (cAMP) invoked as possible second messengers. In the murine thymoma EL4.E1, IL-1 could synergize with the phosphoinositide pathway, because the cells made higher levels of IL-2 in the presence of IL-1 than could be induced by phorbol ester plus calcium ionophore alone. IL-1 is unlikely to act through a sustained increase in cAMP in these cells because it did not raise cAMP levels detectably and because IL-1 and forskolin had opposite effects on IL-2 gene expression. Inducible expression of a transfected reporter gene linked to a cloned fragment of the murine IL-2 gene promoter was initially increased by IL-1 costimulation, implying that IL-1 can increase the rate of transcription of IL-2. The minimal promoter elements required for iL-1 responsiveness were located within 321 bp of the IL-2 RNA cap site, and further upstream sequences to -2800 did not modify this response. IL-1 costimulation resulted in enhanced activity of both an inducible NF-kappa B-like factor and one of two distinct AP-1-like factors that bind to IL-2 regulatory sequences. Neither was induced, however, by IL-1 alone. Another AP-1-like factor and NFAT-1, while inducible in other cell types, were expressed constitutively in the EL4.E1 cells and were unaffected by IL-1. These results are discussed in terms of the combinatorial logic of IL-2 gene expression.

Prevention of thromboembolism after spinal cord injury using low-molecular-weight heparin

OBJECTIVE

To examine the safety and effectiveness of a low-molecular-weight heparin in the prevention of thromboembolism in patients with recent spinal cord injury and complete motor paralysis.

DESIGN

Randomized evaluation of two heparin regimens in 41 consecutive patients meeting eligibility requirements for anticoagulant prophylaxis. Daily bedside examinations were supplemented by serial venous flow studies; suspicious or positive tests were confirmed by venography.

INTERVENTION

Standard heparin, 5000 units subcutaneously three times a day; low-molecular-weight heparin 3500 anti-Xa units subcutaneously once daily.

MEASUREMENTS AND MAIN RESULTS

Five patients in the standard heparin group had thrombotic events, including two patients with fatal pulmonary embolism; two other patients had bleeding severe enough to necessitate withdrawing the heparin. The cumulative event rate was 34.7% (95% CI, 13.7% to 55.2%). None of the patients treated with low-molecular-weight heparin had thrombosis or bleeding (CI, 0% to 14%). The difference between the two groups was significant (P = 0.006, log-rank test).

CONCLUSIONS

Low-molecular-weight heparin is safe and effective in the prevention of thromboembolism in selected patients with spinal cord injury and complete motor paralysis, and is superior to standard heparin in fixed doses of 5000 units three times a day.

[Study on several systems used for chemiluminescent determination of horseradish peroxidase]

Four systems were studied used for chemiluminescent determination of HRP and the determination conditions optimized. In luminol-H2O2 (NaOH) system, HRP was determined conveniently in the range of 0.05-4 pmol, with a correlation coefficient of 0.998 for the linear log-log equation and a limit of detection of 16 fmol HRP. In pyrogallol-H2O2 (pH 6.5) system, 0.1-100 pmol of HRP were determined, based on three log-log regression equations with correlation coefficients of 0.997, 0.994 and 0.999, respectively, and limits of detection of 3-17 fmol HRP. Luminol-H2O2-para iodophenol system was used to determine HRP in the range to 10-50 fmol, based on the chemiluminescence intensity at 1 min and the correlation coefficient of the log-log equation being 0.996 with a limit of detection of 10 fmol HRP. When p-hydroxybiphenyl was used to take the place of p-iodophenol and the chemiluminescence intensity at 1 min or 3 min measured, 6-40 fmol HRP were determined with a correlation coefficient of 0.994 or 0.995 for the log-log equation and a limit of detection of 6.5 or 3.3 fmol HRP.

Intracellular RNA synthesis directed by temperature-sensitive mutants of simian rotavirus SA11

The kinetics of intracellular synthesis of single-stranded (ss) RNA and double-stranded (ds) RNA directed by prototype temperature-sensitive (ts) mutants representing the 10 mutant groups of rotavirus SA11 were examined. Cells were infected with individual mutants or wild type under one-step growth conditions and maintained at permissive temperature (31 degrees) or nonpermissive temperature (39 degrees). At various times postinfection, infected cells were pulse-labeled, ssRNA and dsRNA were purified, RNA species were resolved by electrophoresis and autoradiography, and RNA synthesis was quantitated by computer-assisted densitometry. The mutants representing all groups synthesized significantly less ssRNA and dsRNA at both 31 degrees and 39 degrees, when compared to wild type. When the ratio of synthesis at 39 degrees/31 degrees was determined for ssRNA and dsRNA of each mutant, three RNA synthesis phenotypes were evident. The tsB(339), tsC(606), and tsE(1400) mutants synthesized both ssRNA and dsRNA in a temperature-dependent manner. The group G mutant, tsG(2130), synthesized ssRNA in temperature-independent fashion but was temperature-dependent for the synthesis of dsRNA. The remaining mutants, tsA(778), tsD(975), tsF(2124), tsH(2384), tsI(2403), and tsJ(2131), synthesized both ssRNA and dsRNA in a temperature-independent fashion. The RNA synthesis phenotypes of the ts mutants are discussed in terms of what is known of the function(s) of the protein species to which ts lesions have been assigned.

[Determination of indapamide in human serum by high performance liquid chromatography]

A HPLC method for determination of indapamide in human serum with Sulfisoxazole as internal standard has been established. This method was carried out ODS column (5 microns). We used a mobile phase of acetonitrile: 0.05 mol/L sodium acetate buffer at pH 3.72 (45:55 V/V) and a flow rate of 1.2 ml/min. The procedure was as follows: Transfer 0.5 ml of patient serum add 10 microliters of the internal standard (0.2 mg/ml) and 9 ml ethyl acetate into 12 ml of glass centrifuge tube. Shake for 10 minutes and centrifuge at 3000 r/min for 10 minutes. Transfer the ethyl acetate phase into another tube and evaporate to dryness at 70 c under a nitrogen steam. Reconstitute the residue with methanol 50 microliters and inject 15 microliters into the chromatograph. This method is simple, rapid, sensitive and has a good linearity. The average recoveries of indapamide and internal standard were 99.5% and 98.5% respectively. The method was linear from 0.04 micrograms/ml to 0.5 micrograms/ml with correlation coefficient of 0.9998. The coefficient of variation was less than 4.6% within a day (n = 8) and less than 4.3% between days (n = 8) respectively.

Drug performance sensitivity: a pilot study

Thirty noninsomniac healthy adult men were enrolled in a multicenter pilot study to evaluate the sensitivity of psychomotor and cognitive tasks and subjective evaluation of performance and mood after treatment with flurazepam (Dalmane) 45 mg (larger than the recommended prescribing dose of 15-30 mg). This pilot study was also used to standardize testing procedures. The subjects were given either flurazepam or placebo at 72-hour intervals in a double-blind Latin square crossover design. Choice reaction time, but not simple reaction time, was drug sensitive. Divided attention and vigilance tasks were also sensitive to drug effects. Of the two cognitive tasks tested, addition was impaired by drug, but reading comprehension was not. Subjective evaluations of performance and mood states indicate that these are useful measures, but responses on the Hopkins Symptom Checklist were not influenced.

Trans-acting factors in chromosomal instability

The hypothesis that trans-acting factors affect chromosome stability was explored using human X Chinese hamster somatic cell hybrids. Two types of hybrids were examined. In either case, the human parent consisted of human diploid fibroblasts, the chromosomes of which tended to be lost from the hybrid cell. Comparisons were made between hybrid clones in which the hamster parent had a very stable karyotype (line CHO) and clones from a hamster parent with an unusual ongoing unstable karyotype (line CHX). Chinese hamster-human hybrid cell clones were expanded, and metaphase spreads were analyzed with an in situ hybridization procedure that uses biotin-labeled human genomic DNA as probe. Analyses of chromosome numbers and interspecies translocations were made after 20, 60, and 100 population doublings. Throughout the experiments, the generation of human-hamster-translocated chromosomes was more frequent in the hybrid cells with the CHX background. In addition, these cells also generated human acentric fragments, which were rare in cells with the CHO background. These results favor explanations for the instability of the CHX line that involve ongoing production of a diffusible clastogenic factor.

Ethyl carbamate metabolism: in vivo inhibitors and in vitro enzymatic systems

The metabolism of ethyl carbamate and the localization of its metabolites have been shown to be almost completely inhibited by ethanol in the mouse [Waddell, Marlowe, Pierce: Food Chem. Toxicol.25, 527 (1987); Yamamoto, Pierce, Hurst, Chen, Waddell: Drug Metab. Dispos. 16, 355 (1988)]. The enzyme system catalyzing this metabolism which is inhibited by ethanol now has been further investigated in both in vivo and in vitro studies. There is a direct, highly significant relationship between the extent of metabolism of ethyl carbamate and covalent binding of metabolites to liver protein. Paraoxon, carbaryl, CCl4 ethanol, methimazole, 4-methylpyrazole, diethyl maleate, ethyl N-hydroxycarbamate, and t-butyl carbamate inhibit, to different extents, the metabolism of ethyl carbamate in vivo; SKF-525A, CoCl2, Cacyanamide, chloral hydrate, 2-oxo-4-thiazolidine carboxylic acid, allopurinol, and methyl carbamate do not. Porcine liver esterase, yeast aldehyde dehydrogenase and mouse liver catalase catalyzed the metabolism in vitro; dog or bovine catalase, acid phosphatase, alcohol dehydrogenase, or carbonic anhydrase did not under the conditions tested. Paraoxon, 4-methylpyrazole, carbaryl, and NaF significantly inhibited the hydrolytic activity of mouse liver homogenates toward p-nitrophenyl acetate; ethanol or ethyl carbamate did not. However, each of these, except 4-methylpyrazole, inhibited the metabolism of ethyl carbamate by mouse liver homogenate or porcine liver esterase to about the same extent. Ion exchange chromatography of mouse liver cytosol revealed that the fraction with ability to metabolize ethyl carbamate co-chromatographed almost exactly with the ability to hydrolyze p-nitrophenyl acetate. It is proposed that ethyl carbamate is metabolized in the mouse, at least partially, by esterases; however, metabolism by other enzyme systems cannot be excluded.

[Comparison of bacteriostatic ability of oleum of Perilla frutescens (L.) Britt., Cinnamomum cassia Presl and Nipagin A]

A comparison of bacteriostatic ability has been carried out among oleum of Perilla frutescens and Cinnamomum cassia, benzoic acid and nipagin A. The result shows that the inhibiting effect of Perilla frutescens and Cinnamomum cassia on microorganisms inoculated and spontaneously contaminated is similar to or obviously superior to nipagin A and benzoic acid.

Malaria chemoprophylaxis among European tourists in tropical Africa: use, adverse reactions, and efficacy

In order to determine knowledge, attitudes and practices towards malaria prophylaxis, as well as its side-effects and efficacy, a self-administered questionnaire was distributed to European travellers on return flights from tropical Africa to Europe. Between 1985 and 1988 the questionnaire was completed by 44,472 passengers (80.1% of those on board) on 242 flights. A follow-up questionnaire was completed by 42,202 (94.9%) of the same travellers 3 months later. Almost all knew about the risk of malaria, but 10% relied solely on advice from nonmedical sources. While 55.6% had taken at least one measure against mosquito bites, only 4.5% adopted three such measures (used repellents and insecticides and wore long clothing after dusk). Compliance with chemoprophylaxis use was reported by 57.0% of travellers who spent less than 3 months in Africa, compared with 29.2% who stayed 3-12 months. Depending on the antimalaria regimen taken, 11-44% of the travellers experienced adverse effects, while four deaths were attributed to the chemoprophylaxis. The incidence of malaria per month of exposure for travellers who took no chemoprophylaxis was 15.2 per 1000 in East Africa and 24.2 per 1000 in West Africa. In East Africa, the prophylactic efficacy of the currently recommended antimalaria regimens (relative to that of no chemoprophylaxis) was zero for a chloroquine dosage of 300 mg base per week (4 malaria fatalities), 64.1% for a chloroquine dosage of 600 mg base per week (P = 0.03), and 94.0% for mefloquine (P = 0.003).

Cardiac pacemaker inhibition by transcutaneous electrical nerve stimulation

The use of transcutaneous electrical nerve stimulation (TENS) has increased in recent years for the management of chronic pain. One of its few contraindications is the presence of a cardiac pacemaker. Clinicians have recommended that cardiac monitoring be performed for a short interrupted period during the first application of TENS to ensure safety. We present two patients who were given trials of TENS for different chronic pain complaints. In both cases, electrocardiograms during the TENS trial did not reveal cardiac pacemaker dysfunction, but extended cardiac monitoring with the Holter monitor showed interference with pacemaker function. The abnormalities did not recur after reprogramming the sensitivity of the pacemakers. We suggest the use of extended cardiac monitoring for patients with cardiac pacemakers during the prolonged use of TENS to ensure safety and to determine any need for reprogramming of the pacemakers. Patients with cardiac pacemakers should not be excluded from the use of TENS, but careful evaluation and extended cardiac monitoring should be performed.

Amphiphilic networks: II. Biocompatibility and controlled drug release of poly[isobutylene-co-2-(dimethylamino)ethyl methacrylate]

Biocompatibility and diffusional characteristics of recently synthesized unique amphiphilic networks, i.e., copolymers of methacryloyl-capped polyisobutylene (MA-PIB-MA) with 2-(dimethylamino)-ethyl methacrylate (DMAEMA) have been examined. Excellent biocompatibility and biostability were obtained after 7 weeks with films containing 53-58% MA-PIB-MA implanted dorsally or abdominally in rats. In contrast, networks with higher or lower MA-PIB-MA contents showed decreased biocompatibility. These amphiphilic networks were also studied as potential implantable drug release systems. Bromophenol blue and folic acid were used as model compounds for drug release. Diffusion of these chemicals from loaded networks into water showed a marked pH dependence. Under specific well-defined conditions (MA-PIB-MA/DMAEMA content, pH, time range) release was observed to be independent of time (zero-order release).

Analysis of reassortment and superinfection during mixed infection of Vero cells with bluetongue virus serotypes 10 and 17

The reassortment of genome segments during mixed infection of Vero cells with bluetongue virus (BTV) serotypes 10 and 17 was investigated, using non-selective conditions for analysis of the progeny of mixed infections. Reassortment was found to be an early event in the BTV replication cycle, indicating that progeny BTV genomes undergo a single round of reassortment. Non-random segregation of individual genome segments was observed in crosses at equal multiplicity of infection, and was confirmed in crosses performed at unequal multiplicity. Asynchronous infections showed that superinfection exclusion resulted in the failure of the superinfecting virus to contribute genome segments to reassortants if the second virus followed the first by more than 4 h. The significance of these results for the evolution and epidemiology of BTV is discussed.

From playgroup to preschool: facilitating early integration experiences

This paper discusses community playgroup and preschool settings for non-disabled children as programme options for infants and preschoolers with a variety of physical and mental impairments. These options provide age-appropriate integration experiences which may result in benefits to parent and child, realistic developmental expectations, and a cultural expectation that social integration is a basic part of any child's education. The discussion identifies advantages to beginning integration before the age of 5 years and emphasizes the need for individualized services, ongoing staff training, support for parents, and programme evaluation.