Peritonitis during continuous ambulatory peritoneal dialysis in children.

The use of continuous ambulatory peritoneal dialysis (CAPD) in children has proved beneficial. However, peritonitis remains the major complication. A review of the incidence of peritonitis in 55 children (mean age 9.6 years) who underwent CAPD between 1978 and 1984 showed that there were 67 episodes of peritonitis (1 per 9.4 patient-months) in 33 of the 55. Three patients accounted for 22 of the episodes. In all cases, treatment with antibiotics, given intraperitoneally, was successful. Cephalothin was routinely given for infections due to gram-positive organisms, tobramycin for infections due to gram-negative organisms. Peritonitis recurred in seven patients, of whom five had to have their catheters replaced because of associated chronic infections of the deep peritoneal cuff, the exit site or the catheter tunnel. Although peritonitis was a common complication of CAPD in this population, it did not affect the success of the technique.     

Evidence for false aneuploid peaks in flow cytometric analysis of paraffin-embedded tissue

It has recently been shown that bimodal histograms with false aneuploid peaks may be obtained by DNA flow cytometry from histologically normal tissue allowed to autolyze. To investigate if such peaks can be generated from surgically excised archival tissue, 198 paraffin blocks from 179 patients containing histologically normal spleen (n = 65), liver (n = 26), thyroid (n = 32), pancreas (n = 19), salivary gland (n = 49), or lymph node tissue (n = 7), obtained from the archives of two university pathology departments, were analyzed for nuclear DNA content. The great majority (n = 160, 83.8%) of the 191 interpretable histograms had a single symmetrical G1 peak; and 8 histograms, all produced from liver tissue had a tetraploid pattern. A slight or a prominent repeatable deviation in the G1 peak outline was present in 14 (7.3%) cases. A peak resembling an aneuploid G1 peak with a DNA index (DI) ranging from 1.14 to 1.38 was repeatedly produced from 9 (4.7%) blocks containing histologically normal or inflamed splenic (n = 3), pancreatic (n = 3), liver (n = 1), thyroid (n = 1), or lymph node (n = 1) tissue. The three abnormal peaks produced from pancreatic tissue were rounded in shape and resembled closely the ones that can be obtained from autolytic pancreatic tissue, and the six remaining extra peaks were all fused with the "diploid" peak. In conclusion, false peaks, probably caused by degradation of the nuclear contents during formalin fixation or before it, may rarely be obtained from surgical paraffin-embedded samples.     

Import of human bifunctional enzyme into peroxisomes of human hepatoma cells in vitro.

A polypeptide containing the carboxyl-terminal fragment of human peroxisomal enoyl-CoA hydratase:3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme was synthesized in vitro from its cDNA clone. This expression polypeptide was transported into purified rat liver peroxisomes. When the expression polypeptide was incubated with postnuclear supernatant fractions of human hepatoma cells and analyzed by Nycodenz gradient SDS-PAGE and fluorography, it was imported specifically into peroxisomes as indicated by its resistance to proteinase K degradation. A deletion of the last nine amino acid residues at the carboxyl-terminus of this polypeptide prevents its peroxisomal import. A tripeptide sequence, SKL, located at the carboxyl-terminus of human bifunctional enzyme appears to be the targeting signal for the peroxisomal importation of bifunctional enzyme in human cells.     

HIV coreceptors,cell tropism and inhibition by chemokine receptor ligands

HIV is a persistent virus that survives and replicates despite an onslaught by the host's immune system. A strategy for cell entry, requiring the use of two receptors, has evolved that may help evade neutralizing antibodies. HIV and SIV usually require both CD4 and a seven transmembrane (7TM) coreceptor for infection. At least eleven different 7TM coreceptors have been identified that confer HIV and/ or SIV entry. For HIV-1, the major coreceptors are CCR5 and CXCR4, while the role of other coreceptors for replication and cell tropism in vivo is currently unclear. Polymorphisms in the CCR5 gene that reduce CCR5 expression levels, protect against disease progression, suggesting that drugs targeted to CCR5 could be effective. Such therapies however will not work if HIV simply adapts to use alternative coreceptors. In the light of these themes, this review will discuss the following topics: (i) the coreceptors used by primary HIV-1 and HIV-2 viruses, (ii) the properties and coreceptors of HIV-2 strains that infect cells without CD4, (iii) the role of coreceptors in HIV cell tropism and particularly macrophage infection and (iv) the properties of chemokine receptor ligands that block HIV infection.     

TAC-TIC therapy with premature infants: a series of investigative studies

This article provides a synopsis of a series of studies exploring the effects of TAC-TIC (Touching And Caressing-Tender In Caring) therapy with premature infants. Study 1 looked at the short and long-term effects and found enhanced mental development in the stroked infants at 15 months. In study 2 the physiological effects of an abbreviated version of TAC-TIC with high-risk ventilated infants were examined and it was concluded that TAC-TIC exerted no harm to these vulnerable infants. The behavioural reactions of a sample of premature and low birthweight infants to TAC-TIC and parental responses to administering it were explored in study 3. The infants were found to respond predominantly with arm and leg movements to TAC-TIC while fathers and mothers reported enjoying performing TAC-TIC and elicited a similar pattern and frequency of behavioural reactions. In study 4 the question of whether TAC-TIC benefits preterm infant learning and/or sucking behaviour was investigated. The conclusion reached was that TAC-TIC may potentially benefit cognitive performance within the neonatal period and that this may be an early indicator of long-term cognitive gains reported by previous studies. Using a matched subjects design, study 5 explored the impact of TAC-TIC upon the digestive system by analysing gastric aspirates before and after TAC-TIC and a control period of time. It was concluded that TAC-TIC appeared to induce a more suitable stomach environment for digestion.     

Origin of human immunodeficiency virus type 1 quasispecies emerging after antiretroviral treatment interruption in patients with therapeutic failure

The emergence of antiretroviral (ARV) drug-resistant human immunodeficiency virus type 1 (HIV-1) quasispecies is a major cause of treatment failure. These variants are usually replaced by drug-sensitive ones when the selective pressure of the drugs is removed, as the former have reduced fitness in a drug-free environment. This was the rationale for the design of structured ARV treatment interruption (STI) studies for the management of HIV-1 patients with treatment failure. We have studied the origin of drug-sensitive HIV-1 quasispecies emerging after STI in patients with treatment failure due to ARV drug resistance. Plasma and peripheral blood mononuclear cell samples were obtained the day of treatment interruption (day 0) and 30 and 60 days afterwards. HIV-1 pol and env were partially amplified, cloned, and sequenced. At day 60 drug-resistant variants were replaced by completely or partially sensitive quasispecies. Phylogenetic analyses of pol revealed that drug-sensitive variants emerging after STI were not related to their immediate temporal ancestors but formed a separate cluster, demonstrating that STI leads to the recrudescence and reemergence of a sequestrated viral population rather than leading to the back mutation of drug-resistant forms. No evidence for concomitant changes in viral tropism was seen, as deduced from env sequences. This study demonstrates the important role that the reemergence of quasispecies plays in HIV-1 population dynamics and points out the difficulties that may be found when recycling ARV therapies with patients with treatment failure.     

Pneumolysin activates the NLRP3 inflammasome and promotes proinflammatory cytokines independently of TLR4

Pneumolysin (PLY) is a key Streptococcus pneumoniae virulence factor and potential candidate for inclusion in pneumococcal subunit vaccines. Dendritic cells (DC) play a key role in the initiation and instruction of adaptive immunity, but the effects of PLY on DC have not been widely investigated. Endotoxin-free PLY enhanced costimulatory molecule expression on DC but did not induce cytokine secretion. These effects have functional significance as adoptive transfer of DC exposed to PLY and antigen resulted in stronger antigen-specific T cell proliferation than transfer of DC exposed to antigen alone. PLY synergized with TLR agonists to enhance secretion of the proinflammatory cytokines IL-12, IL-23, IL-6, IL-1β, IL-1α and TNF-α by DC and enhanced cytokines including IL-17A and IFN-γ by splenocytes. PLY-induced DC maturation and cytokine secretion by DC and splenocytes was TLR4-independent. Both IL-17A and IFN-γ are required for protective immunity to pneumococcal infection and intranasal infection of mice with PLY-deficient pneumococci induced significantly less IFN-γ and IL-17A in the lungs compared to infection with wild-type bacteria. IL-1β plays a key role in promoting IL-17A and was previously shown to mediate protection against pneumococcal infection. The enhancement of IL-1β secretion by whole live S. pneumoniae and by PLY in DC required NLRP3, identifying PLY as a novel NLRP3 inflammasome activator. Furthermore, NLRP3 was required for protective immunity against respiratory infection with S. pneumoniae. These results add significantly to our understanding of the interactions between PLY and the immune system.