Distinct Niemann-Pick Disease Type C Clinical, Cytological, and Biochemical Phenotype in an Adult Patient With 1 Mutated, Overexpressed NPC1 Allele

Abstract Niemann-Pick disease type C (NP-C) is a rare autosomal-recessive neurovisceral lysosomal storage disease. We report on a juvenile onset, now 25-year-old female patient with typical neurologic symptoms, including vertical gaze palsy, of NP-C. The diagnosis was supported by a positive filipin test ("variant biochemical phenotype" of cholesterol accumulation) in cultured fibroblasts, high numbers of "Niemann-Pick cells" in the bone marrow, and 1 positive out of 3 NP-C biomarkers tested, but NP-C was not definitely confirmed genetically. She showed only 1 known NPC1 variant (3 bp deletion in exon 18; p.N916del); this allele, however, being distinctly overexpressed at the messenger RNA level as compared to the wild-type allele, as a not as yet clarified (copathogenic?) phenomenon. The patient's mother, also carrying the p.N916del allele but without overexpression, has a chronic inflammatory disease of the central nervous system classified as multiple sclerosis. However, her severe clinical phenotype includes some signs also consistent with NP-C. The laboratory diagnosis of NP-C can be challenging in detecting novel disease constellations.

Optimized quantification of lymphocyte subsets by use of CD7 and CD33.

Identification and quantification of lymphocyte subsets is based on the expression of specific cell surface antigens. As only a minority of these structures is lineage-restricted gating strategies were established, which should permit to include a maximum of lymphocytes, to reach a high purity within the gate and to avoid specific loss of subsets. Two problems remain: First, the incomplete removal of nonlymphoid cells when CD14 is used to exclude them from the lymphocyte gate. Second, the lack of a restricted marker to identify NK cells that are usually defined as CD3(-) /CD16/56(+) lymphocytes, though contaminating monocyte subsets share the expression of CD16, respectively, CD56. This study demonstrates the advantage of CD33 over CD14 at the creation of a pure lymphocyte gate, because CD33 enables the exclusion of all monocyte subpopulations as well as basophils and granulocytes. Independent of the applied NK cell marker mean purity was significantly higher, when CD33 was used (P < 0.001). For the identification of NK cells, CD7 was compared with CD16/56 and with single stained CD56. CD7 and CD16/56 exhibited as equivalent in various CD33 settings (P ≥ 0.173), whereas the mean proportion of CD56(+) NK cells was significantly lower (P ≤ 0.008). Use of CD14 entailed a significantly higher amount of CD3(-) /CD16/56(+) cells than of CD3(-) /CD7(+) cells (P = 0.008) because of the remaining CD14(-) /CD16(+) monocytes. As CD7 is restricted to T cells and NK cells in peripheral blood, misclassification of contaminating monocytes is avoided and CD7(+) NK cells can be identified by lack of CD3. Applying this new selection of mAbs, we reached a mean purity of ≥99.50% within the revised lymphocyte gate. As gates can be set very broadly, high inclusivity and high purity are not mutually exclusive. We propose the adoption of CD7 and CD33 for the quantification of lymphocyte subsets.

Circulating retinol-binding protein 4 and metabolic syndrome in the elderly.

BACKGROUND: Retinol-binding protein (RBP) 4, a human adipokine that specifically binds to retinol, has been reported to provide a link between obesity and insulin resistance. Plasma RBP4 concentration may be under the influence of age and obesity, but only a few studies has investigated this link in elderly individuals. Consequently, we tested the correlation between RBP4 concentrations and type 2 diabetes/metabolic syndrome (MetS) components in a large population based cohort study (VITA) of elderly [1, 2]. Using a single birth cohort, this investigation could exclude the influence of age. METHODS: We evaluated the correlation of RBP4 with type 2 diabetes and MetS components including Body Mass Index (BMI), blood pressure, lipid parameters, fasting glucose insulin, homeostasis model assessment insulin resistance (HOMA-IR), and smoking in exclusively 75-76 year old participants (N = 232). RESULTS: In the present study, RBP4 concentrations were associated with type 2 diabetes and metabolic syndrome (MetS) components. Of all the individual components of metabolic syndrome that were associated with RBP4 concentrations, the correlations of RBP4 with serum triglycerides and a negative correlation with HDL were the strongest ones observed in our study cohort (p<0.0001). CONCLUSIONS: RBP4 plays a role in biological mechanisms that are responsible for insulin resistance and development of type 2 diabetes.

Diagnosis of infection with human herpes viruses in routine laboratory practice.

BACKGROUND: The potential for faster detection of human herpes viruses using PCR compared to other methods is undisputed. However, because of fear of contamination, the clinical implication of nucleic amplification methods in routine laboratories is not widespread. Herpes viruses cause a wide spectrum of diseases and can cause morbidity and mortality in immune-compromised patients. Using real-time PCR, most of the problems associated with PCR (contamination, cumbersome detection, and rather expensive tests) are solved, and a rapid, economical, and--most importantly--closed system is at hand. METHODS: We evaluated work procedures in our laboratory that enable the routine diagnosis of viral infections with high accuracy and rapid turn-around time. In parallel, inherent problems usually associated with PCR testing, especially cross-contamination could be suppressed to a minimum. The start of the work flow process begins with an automated nucleic acid extraction procedure that yields high quality DNA. A common--internally and externally controlled--PCR program for all six viruses allows rapid sample turn around. RESULTS: In all, 7500 analyses for human herpes virus infection were performed in the last 5 years. Results for various different specimens were produced within 24 h. Contamination occurred rarely and could be ameliorated easily. The use of internal controls identified rare PCR-inhibited samples. The detection limits for our assays are markedly below the clinically relevant range. CONCLUSIONS: Our workflow allowed rapid, cost-efficient, and labor saving routine diagnostic detection of viral infections.

Clinical chemistry reference values for 75-year-old apparently healthy persons.

BACKGROUND: Clinical chemistry reference values for elderly persons are sparse and mostly intermixed with those for younger subjects. To understand the links between metabolism and aging, it is paramount to differentiate between "normal" physiological processes in apparently healthy elderly subjects and metabolic changes due to long-lasting diseases. The Vienna Transdanube Aging (VITA) study, which began in 2000 and is continuing, will allow us to do just that, because more than 600 male and female volunteers aged exactly 75 years (to exclude any influence of the "aging" factor in this cohort) are participating in this study. METHODS: Extensive clinical, neurological, biochemical, psychological, genetic, and radiological analyses, with a special emphasis on consumption of medication and abuse of drugs, were performed on each of the probands. The multitude of data and questionnaires obtained made possible an a posteriori approach to select individuals fulfilling criteria for a reference sample group of apparently healthy 75-year-old subjects for our study. Specific analytes were quantified on automated clinical analyzers, while manual methods were used for hormonal analytes. All clinical chemistry analytes were evaluated using in-depth statistical analyses with SPSS for Windows. RESULTS: In all, reference intervals for 45 analytes could be established. These include routine parameters for the assessment of organ functions, as well as hormone concentrations and hematological appraisals. Because all patients were reevaluated after exactly 30 months in the course of this study, we had the opportunity to reassess their health status at the age of 77.5 years. This was very useful for validation of the first round data set. Data of the second round evaluation corroborate the reference limits of the baseline analysis and further confirm our inclusion and exclusion criteria. CONCLUSIONS: In summary, we have established a reliable set of reference data for hormonal, hematological, and clinical chemistry analytes for elderly subjects. These values will be very useful for our future attempts to correlate disease states and aging processes with metabolic factors.

Concentrations of N-terminal pro-brain natriuretic peptide and troponin T in plasma of 75-year-old apparently healthy persons.

Clinical chemical reference values for older persons are sparse and mostly intermixed with those for younger persons. We had a unique opportunity to obtain blood samples from volunteers who were 75 years old and living in two districts of Vienna, Austria. Consequently, we utilized stored plasma samples to obtain reference intervals for 120 apparently healthy 75-year-old participants for pro-brain natriuretic peptide (proBNP), as well as for troponin T. The N-terminal (NT)-proBNP protein assay is currently used as a diagnostic and prognostic aid in patients with heart failure and as a prognostic marker in acute coronary syndromes. Specifically, the concentration of NT-proBNP in serum or plasma aids in the prognosis of ventricular systolic dysfunction and helps to differentiate between cardiac and non-cardiac causes. The median NT-proBNP plasma value for men and women in our cohort was calculated as 98 pg/ml, comparing favorably with reported values, in that a NT-proBNP concentration less than 100 pg/ml excludes acutely decompensated heart failure. Our calculated 97.5 percentile was slightly higher (359 pg/ml) than the 97.5 percentile in a group of 50-65-year-old persons (198 and 222 pg/ml for men and women, respectively) revealing the influence of age on this parameter. Because of its high tissue-specificity, cardiac troponin T is a cardiospecific, highly sensitive marker for myocardial damage. However, the troponin T concentrations in the plasma specimens from this cohort were all below the detection limit of 0.01 ng/ml, preventing any further data handling.