Visceral leishmaniasis: another HIV-associated opportunistic infection? Report of eight cases and review of the literature

Visceral leishmaniasis (VL) is considered an opportunistic infection in immunocompromised patients. We review the clinical, laboratory, and therapeutic data in 63 patients (eight new cases and 55 cases reported in the literature) with Mediterranean VL (kala azar) and HIV-1 infection to determine whether VL should be considered an opportunistic infection in HIV-infected adults. We conclude that: (1) in areas where both leishmaniasis and HIV-1 infection are endemic, VL may be more frequent among HIV-infected adults; (2) in HIV-infected patients, the clinical picture did not differ significantly from classical kala azar, although it often ran a recurrent course, with resistance to antimonial therapy. We propose the inclusion of VL in the IVC-2 subgroup of the Centers for Disease Control (CDC) clinical classification of HIV-1 infection while prospective and larger studies further define whether there are clinical presentations that could justify adding VL to the list of opportunistic infections indicative of AIDS.     

CD97, but not its closely related EGF-TM7 family member EMR2, is expressed on gastric,pancreatic, and esophageal carcinomas

CD97 expression is related closely to the dedifferentiation and tumor stage in thyroid carcinomas. We systematically examined the role of CD97 and its closest relative, EMR2, in normal and malignant gastric, esophageal, and pancreatic tissue. The normal tissues were EMR2-, whereas CD97 was expressed slightly in the parietal cells of gastric mucosa and in exocrine pancreatic cells. Interestingly, intralobular and interlobular pancreatic ducts were CD97+. All tumors were EMR2-. CD97 was expressed by 44 of 50 gastric, 14 of 18 pancreatic, and 10 of 13 esophageal carcinomas. Of the 44 gastric cancers, 27 showed disseminated or scattered tumor cells at the invasion front with stronger CD97 expression than tumor cells located in solid tumor formations. There was no correlation between CD97 levels in the tumors or soluble CD97 in the serum samples and the clinicopathologic features of the patients. Taken together, significant numbers of gastric, esophageal, and pancreatic carcinomas are CD97+, whereas its homolog, EMR2, does not have any role in such tumors.     

Turnip crinkle virus coat protein mediates suppression of RNA silencing in Nicotiana benthamiana

All of the protein products of Turnip crinkle virus (TCV; Tombusviridae, Carmovirus) were tested for their ability to suppress RNA silencing of a reporter gene after transient expression in Agrobacterium-infiltrated Nicotiana benthamiana leaves. Only the capsid protein, P38, showed suppression activity, although this was not obvious when P38 was expressed as part of a TCV infection of the same tissues. When P38 was expressed from a PVX vector, symptoms with enhanced severity that correlated with increased PVX RNA accumulation were observed. This contradiction between ectopic expression of P38 and TCV infection could be accounted for if the active determinant of suppressor activity within P38 was sequestered within the capsid protein structure. The N-terminal 25 amino acids were shown to be important for this activity. This region forms part of the unexposed R-domain that interacts with the RNA within the virus particle. This observation throws light on some of the complex biology exhibited by TCV.     

Molecular genetic characterization of XRCC4 function

XRCC4 is a generally expressed protein of 334 amino acids that is involved in the repair of DNA double-strand breaks and in V(D)J recombination, but its function is unknown. In this study, we have used a mutational approach and the yeast two-hybrid method to perform an initial characterization of this protein. We show that the XRCC4 protein is located in the nucleus. We also demonstrate that several potential phosphorylation sites are not required for XRCC4 function in a transient V(D)J recombination assay. In addition, we show that XRCC4 forms a homodimer in vivo with the homodimerization domain being located within amino acids 115-204. Finally, we define a core domain of XRCC4 that functions in V(D)J recombination and comprises amino acids 18-204. Potential functions of XRCC4 are discussed.      

Clone-based systematic haplotyping (CSH): a procedure for physical haplotyping of whole genomes

We present a novel methodology to determine the phase of single-nucleotide polymorphisms (SNPs) on a chromosome, which we term clone-based systematic haplotyping (CSH). The CSH procedure is based on separating the allelic chromosomes of a diploid genome by fosmid/cosmid cloning, and subsequent SNP typing of 96 clone pools, each representing approximately 10% of the genome. The pools are screened by PCR for the sequence of interest, followed by SNP typing on the PCR products using the GOOD assay. We demonstrate that by CSH, the haplotype of SNPs separated by more than 50 kilobases can definitely be assigned. We propose this method as being suitable for constructing maps of ancestral haplotypes, analysis of complex diseases, and for diagnosis of rare defects in which the molecular haplotype is crucial. In addition, by amplifying the initial DNA by many orders of magnitude, the original DNA resource is effectively immortalized, enabling the haplotyping of hundreds of thousands of SNPs per individual.     

Assay for the specificity of monoclonal antibodies in crossed immunoelectrophoresis

A method is described based on crossed immunoelectrophoresis of a complex antigen mixture in agarose gel followed by incubation of the gel with the monoclonal antibody. The bound monoclonal antibody is detected by the use of a secondary enzyme-labelled antibody.Using this technique we have been able to identify the precipitate arc in crossed immunoelectrophoresis of major histocompatibility complex (MHC) class I molecules in a mixture of all detergent solubilized cell membrane molecules by means of a monoclonal antibody, the specificity of which was known independently to be against MHC class I molecules. In other experiments using the same technique we demonstrated the reaction of a monoclonal antibody specific for chicken Ig light chains.     

Relative contributions of innate and acquired host responses to bacterial control and arthritis development in Lyme disease

TLR2(-/-)/scid double-mutant mice were infected with B. burgdorferi to assess the relative importance of acquired and innate host defenses. Although spirochete levels at 4 weeks were lower in TLR2(-/-) mice than in TLR2(-/-)/scid mice, the increased arthritis severity of TLR2 (Toll-like receptor 2)-deficient mice was reduced by the presence of the scid mutation.     

Potassium and sodium shifts during in vitro isometric muscle contraction,and the time course of the ion-gradient recovery

Intracellular potassium ([K⁺]_i), interstitial potassium ([K⁺]_inter), intracellular sodium ([Na⁺]_i), and resting membrane potential (RMP) were measured before and after repetitive stimulation of mouse soleus and EDL (extensor digitorum longus) muscles. At rest, RMP was –69.8 mV for soleus and –74.9 mV for EDL (37°C). [K⁺]_i was 168 mM and 182 mM, respectively. In soleus, free [Na⁺]_i was 12.7 mM. After repetitive stimulation (960 stimuli) RMP had decreased by 11.9 mV for soleus and by 18.2 mV for EDL. [K⁺]_i was reduced by 32 mM and 48 mM, respectively, whereas [K⁺]_inter was doubled. In soleus [Na⁺]_i had increased by 10.6 mM, demonstrating that the [K⁺]_i-decrease is three times higher than the [Na⁺]_i-increase. It is concluded that this difference reflects different activity induced movements of Na and K, and that the difference is not due to the Na/K pumping ratio. The possible involvement of the potassium loss in muscle fatigue is discussed. After stimulation RMP recovered with a time constant of 0.9 min for soleus and 1.5 min for EDL. Within the first minutes after stimulation the intracellular potassium concentration increased by 20.4 mM/min for soleus and 21.7 mM/min for EDL. Free [Na⁺]_i decreased with less than 10 mM/min. The mechanisms underlying the different rate of changes are discussed.Parts of this work have been published in preliminary form (Juel and Sjøgaard 1984)     

In vitro hemocompatibility of self-assembled monolayers displaying various functional groups

Self-assembled monolayers (SAMs) of alkanethiols with various terminating groups (-OH, -CH3, -COOH) and binary mixtures of these alkanethiols were studied with respect to their hemocompatibility in vitro by means of freshly taken human whole blood. The set of smooth monomolecular films with graded surface characteristics was applied to scrutinize hypotheses on the impact of surface chemical-physical properties on distinct blood activation cascades, i.e. to analyze -OH surface groups vs. complement activation, acidic surface sites vs. contact activation/coagulation and surface hydrophobicity vs. thrombogenicity. Blood and model surfaces were analyzed after incubation for the related hemocompatibility parameters. Our results show that the adhesion of leukocytes is abolished on a -CH3 surface and greatly enhanced on surfaces with -OH groups. The opposite was detected for the adhesion of platelets. A strong correlation between the activation of the complement system and the adhesion of leukocytes with the content of -OH groups could be observed. The contact activation for hydrophilic surfaces was found to scale with the amount of acidic surface sites. However, the coagulation and platelet activation did not simply correlate with any surface property and were therefore concluded to be determined by a superposition of contact activation and platelet adhesion.