HIV DNA Reservoir Increases Risk for Cognitive Disorders in cART-Na?ve Patients

Objectives

Cognitive impairment remains frequent in HIV, despite combination antiretroviral therapy (cART). Leading theories implicate peripheral monocyte HIV DNA reservoirs as a mechanism for spread of the virus to the brain. These reservoirs remain present despite cART. The objective of this study was to determine if the level of HIV DNA in CD14⁺ enriched monocytes predicted cognitive impairment and brain injury.

Methods

We enrolled 61 cART-naïve HIV-infected Thais in a prospective study and measured HIV DNA in CD14⁺ enriched monocyte samples in a blinded fashion. We determined HAND diagnoses by consensus panel and all participants underwent magnetic resonance spectroscopy (MRS) to measure markers of brain injury. Immune activation was measured via cytokines in cerebrospinal fluid (CSF).

Results

The mean (SD) age was 35 (6.9) years, CD4 T-lymphocyte count was 236 (139) and log₁₀ plasma HIV RNA was 4.8 (0.73). Twenty-eight of 61 met HAND criteria. The log₁₀ CD14⁺ HIV DNA was associated with HAND in unadjusted and adjusted models (p = 0.001). There was a 14.5 increased odds ratio for HAND per 1 log-value of HIV DNA (10-fold increase in copy number). Plasma CD14⁺ HIV DNA was associated with plasma and CSF neopterin (p = 0.023) and with MRS markers of neuronal injury (lower N-acetyl aspartate) and glial dysfunction (higher myoinositol) in multiple brain regions.

Interpretation

Reservoir burden of HIV DNA in monocyte-enriched (CD14⁺) peripheral blood cells increases risk for HAND in treatment-naïve HIV+ subjects and is directly associated with CSF immune activation and both brain injury and glial dysfunction by MRS.     

Candida konsanensis sp. nov., a new yeast species isolated from Jasminum adenophyllum in Thailand with potentially carboxymethyl cellulase-producing capability

A new yeast species (KKU-FW10) belonging to the Candida genus was isolated from Jasminum adenophyllum in the Plant Genetic Conservation Project under The Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn area, Chulabhorn Dam, Konsan district within Chaiyaphum province in Thailand. The strain was identified via analysis of nucleotide sequences from the D1/D2 domain of 26S ribosomal DNA and based on its morphological, physiological and biochemical characteristics. The sequence obtained from yeast isolate KKU-FW10 was 97 percent identical to that of Candida chanthaburiensis (GenBank accession number AB500861.1), with 506/517 (nucleotides identity/total nucleotides) matching nucleotides, nine substitutions and two gaps being detected. This species belonged to the Candida clade. Regarding morphological characteristics, isolate KKU-FW10 presents cream-colored butyrous colonies, vegetative reproduction through budding and, round cells without filaments or ascospores. The major ubiquinone detected was Q-9. The above results suggest that isolate KKU-FW10 is a new member of the genus Candida, and the name Candida konsanensis is proposed for this yeast. The type strain of the new species is KKU-FW10^T (= BCC 52588^T, = NBRC 109082^T, = CBS 12666^T). In addition, this KKU-FW10 could potentially produce 58.24 Units/ml of carboxymethyl cellulase when it was cultured in YP broth containing 1.0 % carboxymethyl cellulose for 24 h.     

Substrate specificity of alkaline serine proteinase isolated from photosynthetic bacterium,Rubrivivax gelatinosus KDDS1

A novel type of fluorescence resonance energy transfer (FRET) combinatorial libraries were used for the characterization of alkaline serine proteinase produced from Rubrivivax gelatinosus KDDS1. This enzyme was the first serine proteinase characterized from photosynthetic bacteria. The proteinase was found to prefer Met and Phe at the P1 position, Ile and Lys at the P2 position, and Arg and Phe at the P3 position. To date, no serine proteinase has exhibited a preference for Met at the P1 position. Thus, the alkaline serine proteinase from R. gelatinosus KDDS1 is very unique in terms of substrate specificity. A highly sensitive substrate, Boc-Arg-Ile-Met-MCA, was synthesized for kinetic study based on the results reported here. The optimum pH of the enzyme for this substrate was pH 10.7, and the values of kcat, Km, and kcat/Km were 23.7 s(-1), 15.4 microM, and 1.54 microM(-1) s(-1), respectively.     

Purification and characterization of alkaline serine proteinase from photosynthetic bacterium, Rubrivivax gelatinosus KDDS1

In order to reduce the protein content of wastewater, photosynthetic bacteria producing proteinases were screened from wastewater of various sources and stocked in culture. An isolated strain, KDDS1, was identified as Rubrivivax gelatinosus, a purple nonsulfur bacterium that secretes proteinase under micro-aerobic conditions under light at 35 degrees C. Molecular weight of the purified enzyme was estimated to be 32.5 kDa. The enzyme showed the highest activity at 45 degrees C and pH 9.6, and the activity was completely inhibited by phenylmethyl sulfonyl fluoride (PMSF), but not by EDTA. The amino-terminal 24 amino acid sequence of the enzyme showed about 50% identity to those of serine proteinases from Pseudoalteromonas piscicida strain O-7 and Burkholderia pseudomallei. Thus, the enzyme from Rvi. gelatinosus KDDS1 was thought to be a serine-type proteinase. This was the first serine proteinase characterized from photosynthetic bacteria.     

Purification and characterization of a novel polysaccharide involved in the pellicle produced by a thermotolerant Acetobacter strain

Acetobacter strains able to produce a thick pellicle at 37 degrees C were screened among many thermotolerant strains isolated from fruits in Thailand. As a result, Acetobacter sp. SKU 1100 was selected as the producer of a relatively thick pellicle even when cultured at higher temperatures such as 37 degrees C or 40 degrees C. This strain could produce a pellicle polysaccharide in a shaking submerged culture as well as under static culture conditions. The polysaccharide was found to be attached to the bacterial cells. Although the polysaccharide production was higher at 30 degrees C than at 37 degrees C in shaking submerged culture, the productivity in static culture was not decreased even at higher temperatures. The membrane-attached polysaccharide was purified from the SKU 1100 strain by cell disruptions using either ultrasonic treatment or lysozyme treatment, followed by ultracentrifugation, enzyme treatments, dialysis against SDS, DEAE-cellulose column chromatography, alcohol precipitation, and gel filtration chromatography. The polysaccharide purified by the sonic treatment and also by the mild conditions using lysozyme treatment had the same average molecular mass of 120 kDa. The purified polysaccharide was composed of three different monosaccharides; glucose, galactose, and rhamnose, in an approximately equimolar ratio of 1:1:1.     

Evaporation cycle experiments — A simulation of salt-induced peptide synthesis under possible prebiotic conditions

Evaporation cycles applied to dilute solutions of amino acids, Cu(II) and NaCl lead to peptides within 1–3 days. This simulation of possible coastal or laguna processes in a primitive earth environment gives further indications towards the relevance of the salt-induced peptide formation reaction in chemical evolution. The experiments were successfully applied to glycine, alanine, aspartic and glutamic acid. Besides isolated amino acids, also their mixtures with glycine as reaction partner were studied, leading to peptides for all of the aforementioned substances, as well as for valine and proline, which do not dimerize alone. Sequence preferences and some conservation of optical purity were observed.     

Enzymatic Properties of Newly Found Green Turtle Egg White Ribonuclease

Egg white ribonuclease was first found in green turtle eggs. The general properties were studied on substrate specificity, the optimum pH and temperature, and the effect of pH and temperature on the RNase activity. The enzyme studied was specific for poly (C) and degraded poly (U) at the lower rate and had the pH optimum at 7.0 and the optimum temperature at 40 °C. It was stable at alkaline range (pH 8.0–10.0) and up to 60 °C in pH 9.0 for 1 h, and unstable at acidic side for all temperatures. All of the properties studied showed similarity to RNase A. However, the optimum pH, broad range of optimum temperature and pH stability were different from RNase A. To evaluate the relationship of the structure and enzymatic properties, the 3D-structure of this enzyme was engineered by program MODELLER using two RNases (2BWL and 2BLZ) as starting models. The differences found in activity might be affected from the structure of micro environmental changing caused by amino acids deletion and substitution on the molecule.     

Diversity of nitrogen-fixing cyanobacteria under various ecosystems of Thailand: I. Morphology,physiology and genetic diversity

The diversity among 853 isolates of nitrogen-fixing cyanobacteria obtained from soil samples collected from different ecosystems including mountainous, forest and cultivated areas in the central, northern and northeastern regions of Thailand was examined. Most isolates showed slow growth rate and had filamentous, heterocystous cells. The percentage of heterocysts in the filaments of different isolates varied from 8.3 to 9.6. Only a few strains showed high nitrogen-fixing potential, while most of the strains exhibited low capacity for nitrogen fixation. Anabaena and Nostoc were the dominant genera among these isolates. One hundred and two isolates were randomly selected from this diverse collection to determine the extent of genetic diversity on the basis of DNA fingerprinting using the PCR method. Based on the PCR products obtained by using a combination of three primers, all strains could be distinguished from one another. When a subset of 45 isolates of Nostoc and a subset of 44 isolates of Anabaena were further analysed by PCR, a wide range of diversity was observed within each of these genera.