The diagnostic role of urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in the detection of renal tubular impairment

The kidney function can be assessed by a number of methods. The urinary excretion of enzymes, in particular N-acetyl-beta-D-glucosaminidase (NAG), is considered a relatively simple, cheap, fast and non-invasive method in the detection and follow-up of renal tubular function under various conditions. The determination of urinary NAG provides a very sensitive and reliable indicator of renal damage, such as injury or dysfunction due to diabetes mellitus, nephrotic syndrome, inflammation, vesicoureteral reflux, urinary tract infection, hypercalciuria, urolithiasis, nephrocalcinosis, perinatal asphyxia, hypoxia, hypertension, heavy metals poisoning, treatment with aminoglycosides, valproate, or other nephrotoxic drugs. This paper gives an overview of the current use of urinary NAG in the detection of renal injury.     

The genetic basis of antibody production: the dominant anti-arsonate idiotype response of the strain A mouse

Immunization of the A strain of mice with the hapten p-azophenylarsonate (Ars) results in an immune response in which approximately 50% of the anti-Ars antibodies share cross-reactive idiotypic determinants (IdCR). A gene or genes linked to the heavy chain constant region locus is required for the production of this idiotype. The expressed VH gene from a hybridoma cell line which expresses the IdCR has been cloned. DNA hybridization studies utilizing the VH gene have revealed that there are many related genes in both idiotype-producing and idiotype-nonproducing strains of mice. However, under stringent hybridization conditions, only a single band of 6.4 kb is present in Eco R1-digested A strain DNA. Strains of mice which are phenotypically idiotype-negative either lack this band completely or possess a much weaker one at this position. Utilizing DNA from Igh recombinant strains of mice, it has been shown that the VH locus controlling idiotype expression contains the structural gene information for the idiotype-positive heavy chains. It has also been shown that DNA at this locus appears to be sufficient for the production of the cross-reactive idiotype. Utilizing a DNA probe derived from regions flanking the structural gene has confirmed the relatedness of V genes in a variety of mouse strains and revealed a significant degree of polymorphism at the Igh locus.     

Genetic control of hematopoietic stem cell frequency in mice is mostly cell autonomous

Previously we reported that the size of the stem cell compartment (measured as LTC-IC) is 11-fold greater in DBA/2 than in C57BL/6 mice, and we identified genes that regulate the size of the stem cell pool. To determine whether stem cell intrinsic or extrinsic events account for these differences, we created chimeras by aggregating morulae from the strains C57BL/6 and DBA/2. In these chimeras stem cells of both genotypes are exposed to a common mixed environment. Thus, an equalization of stem cell frequencies is expected if stem cell extrinsic effects dominate. Conversely, the parental ratio of LTC-IC should be preserved if the regulation is stem cell autonomous. For each chimera, individual LTC-IC were genotyped on the clonal levels by analyzing their progeny. We found that most of the difference that regulates the size of the stem cell compartment was intrinsic.     

Modified orthostatic load for spectral analysis of short-term heart rate variability improves the sensitivity of autonomic dysfunction assessment

AimTo evaluate the impact of orthostatic load for sensitivity of short-term spectral analysis of heart rate variability (HRV) assessment of potential early autonomic dysfunction in diabetes mellitus.MethodsComparison of results of short-term time- and frequency-domain analysis of HRV during single positions and during modified orthostatic load (supine 1–standing–supine 2, each position 300 s) in diabetic subjects with good glycemic control (n=80, age 38±14, diabetes duration 16±10 years) and without autonomic neuropathy as assessed by a standard bedside reflex test battery, and in nondiabetic controls (n=150, age 40±13 years).ResultsNone of the short-term frequency-domain parameters [absolute and logarithmic (LN) values of spectral powers in total- (TF), low- (LF), and high-frequency (HF) bands and its centroid frequencies] as obtained in single positions “supine” or “standing” revealed a significant difference between well-controlled patients and healthy controls (P>.3). However, during modified orthostatic load, significant differences in ΔLN TF_{(supine 1–supine 2)} and in ΔLN LF_{(supine 1–supine 2)} as well as in ΔLN LF_{(standing–supine 2)} values between diabetic and healthy subjects were recorded [?0.2±0.5 vs. ?0.1±0.4 LN (ms²), P=.05; ?0.3±0.8 vs. 0.1±0.7 LN (ms²), P=.001 and 0.2±1.0 vs. 0.4±0.9 LN (ms²), P=.05, respectively] with insignificant intergroup differences in related centroid frequencies. This finding suggests a delayed recovery of LF spectral power in diabetic subjects after orthostatic challenge.ConclusionsWhen compared with single position measurements, the modified orthostatic load protocol improves the sensitivity of short-term HRV examination. In well-controlled diabetic subjects without cardiovascular autonomic neuropathy (as excluded by standard cardiovascular reflex testing), the delayed recovery of LF band spectral power after orthostatic load with standing up indicates diminished parasympathetic activation.     

Comparative full genome analysis of four infectious laryngotracheitis virus (Gallid herpesvirus-1) virulent isolates from the United States

Gallid herpesvirus-1 (GaHV-1), commonly named infectious laryngotracheitis (ILT) virus, causes the respiratory disease in chickens known as ILT. The molecular determinants associated with differences in pathogenicity of GaHV-1 strains are not completely understood, and a comparison of genomic sequences of isolates that belong to different genotypes could help identify genes involved in virulence. Dideoxy sequencing, 454 pyrosequencing and Illumina sequencing-by-synthesis were used to determine the nucleotide sequences of four genotypes of virulent strains from GaHV-1 groups I-VI. Three hundred and twenty-five open reading frames (ORFs) were compared with those of the recently sequenced genome of the Serva vaccine strain. Only four ORFs, ORF C, U(L)37, ICP4 and U(S)2 differed in amino acid (aa) lengths among the newly sequenced genomes. Genome sequence alignments were used to identify two regions (5' terminus and the unique short/repeat short junction) that contained deletions. Seventy-eight synonymous and 118 non-synonymous amino acid substitutions were identified with the examined ORFs. Exclusive to the genome of the Serva vaccine strain, seven non-synonymous mutations were identified in the predicted translation products of the genes encoding glycoproteins gB, gE, gL and gM and three non-structural proteins U(L)28 (DNA packaging protein), U(L)5 (helicase-primase) and the immediate early protein ICP4. Furthermore, our comparative sequence analysis of published and newly sequenced GaHV-1 isolates has provided evidence placing the cleavage/packaging site (a-like sequence) within the inverted repeats instead of its placement at the 3' end of the U(L) region as annotated in the GenBank's entries NC006623 and HQ630064.     

Plasmapheresis-induced clinical improvement in a patient with steroid-resistant nephrotic syndrome due to podocin (NPHS2) gene mutation

Podocin mutations (NPHS2 gene) are mostly responsible for steroid-resistant nephrotic syndrome (SRNS) of childhood onset. Patients with NPHS2 gene mutations do not respond to corticoids and other immunosuppressive agents; partial remission can be rarely induced by cyclosporin A. We present a boy, where SRNS was diagnosed within first year of life. By the age of 15 years, proteinuria reached 9000 mg/24 h, cholesterolemia 15 mmol/L, albuminemia 19.6 g/L, in spite of combined therapy with cyclosporine A, methylprednisolone, enalapril and losartan. At that time a combined heterozygous form of two NPHS2 gene mutations (p.R138Q and p.V290M) was diagnosed, methylprednisolone was discontinued and patient underwent ten plasmapheresis procedures. This resulted in clinical improvement (proteinuria 3000 mg/24 h, S-cholesterol 6 mmol/L, albumin 30g/L) lasting for three years. In conclusion, plasmapheresis can result in clinical improvement and stabilization of SRNS caused by podocine mutation, before renal replacement therapy is initiated.