Reference intervals for CTX and P1NP in a multi-ethnic Malaysian cohort

BACKGROUND

Well defined reference intervals are central to the utility of serum C-terminal telopeptide of type 1 collagen (CTX) and N-terminal propeptide of type I procollagen (P1NP), designated as reference markers in osteoporosis, and useful for monitoring therapeutic response in that condition. This study reports the reference intervals for plasma CTX and serum P1NP in a multi-ethnic Malaysian population.

METHODS

Ethnic Malay, Chinese or Indian subjects aged 45-90 years old were recruited from Selangor, Malaysia from June 2016 to August 2018. Subjects with known medical conditions (e.g., bone disorders, malnutrition, immobilisation, renal impairment, hormonal disorders) and medications (including regular calcium or vitamin D supplements) that may affect CTX and P1NP were excluded. Additionally, subjects with osteoporosis or fracture on imaging studies were excluded. The blood samples were collected between 8 a.m. and 9 a.m. in fasting state. The CTX and P1NP were measured on Roche e411 platform in batches.

RESULTS

The 2.5th-97.5th percentiles reference intervals (and bootstrapped 90%CI) for plasma CTX in men (n = 91) were 132 (94-175) - 775 (667-990) ng/L; in post-menopausal women (n = 132) 152 (134-177) - 1025 (834-1293) ng/L. The serum P1NP reference intervals in men were 23.7 (19.1-26.4) - 83.9 (74.0-105.0) µg/L, and in post-menopausal women, 25.9 (19.5-29.3) - 142.1 (104.7-229.7) µg/L.

CONCLUSION

The reference intervals for plasma CTX and serum PINP for older Malaysian men and post-menopausal women are somewhat different to other published studies from the region, emphasising the importance of establishing specific reference intervals for each population.

Missed diagnosis of influenza B virus due to nucleoprotein sequence mutations, Singapore, April 2011

A new influenza B variant was discovered in Singapore in April 2011 during diagnostic testing of a 3-year-old boy with respiratory symptoms. Influenza B virus was isolated from culture and confirmed by standard immunofluorescence testing, but was not detected by the routine, in-house influenza screening reverse-transcription polymerase chain reaction assay that targets the nucleoprotein (NP) gene. Subsequent sequencing investigations demonstrated that several other published assays targeting NP could also fail to detect this novel variant.

Missed diagnosis of influenza B virus due to nucleoprotein sequence mutations, Singapore, April 2011

A new influenza B variant was discovered in Singapore in April 2011 during diagnostic testing of a 3-year-old boy with respiratory symptoms. Influenza B virus was isolated from culture and confirmed by standard immunofluorescence testing, but was not detected by the routine, in-house influenza screening reverse-transcription polymerase chain reaction assay that targets the nucleoprotein (NP) gene. Subsequent sequencing investigations demonstrated that several other published assays targeting NP could also fail to detect this novel variant.

Diverse cyclization catalyzed by In(OTf)3 for the convergent assembly of substituted tetrahydrofurans and tetrahydropyrans

[reaction: see text]. A novel In(OTf)3-catalyzed (3,5) oxonium-ene type cyclization for the facile construction of various multisubstituted tetrahydrofurans and tetrahydropyrans was successfully developed. Further mechanistic investigations unveiled an In(OTf)3-catalyzed skeletal reorganization of the tetrahydrofuran to its thermodynamic isomer under thermal conditions.

Synthetic studies toward anisatin: a formal synthesis of (+/-)-8-deoxyanisatin

[figure: see text] An efficient strategy to construct the congested C-7a quaternary chiral center of anisatin was developed, by way of an Eschenmoser-Claisen rearrangement. Conversion of the resultant amide to Kende's epsilon-lactone intermediate 3 in four steps completed a concise formal synthesis of (+/-)-8-deoxyanisatin (2).

Adaptation to persistent growth in the H9 cell line renders a primary isolate of human immunodeficiency virus type 1 sensitive to neutralization by vaccine sera

Seven diverse primary isolates of human immunodeficiency virus type 1 (HIV-1) were examined and found to be refractory to neutralization by antisera to recombinant gp120 (rgp120) protein from HIV-1 MN. This stands in marked contrast to the sensitivity exhibited by certain laboratory-adapted viruses. To understand the difference between primary and laboratory-adapted viruses, we adapted the primary virus ACH 168.10 to growth in the FDA/H9 cell line. ACH 168.10 was chosen because the V3 region of gp120 closely matches that of MN. After 4 weeks, infection became evident. The virus (168A) replicated in FDA/H9 cells with extensive cytopathic effect but was unchanged in sensitivity to antibody-mediated neutralization. Thus, growth in cell lines is not sufficient to render primary virus sensitive to neutralization. The 168A virus was, however, partially sensitive to CD4 immunoadhesin (CD4-Ig). Adaptation was continued to produce a persistently infected FDA/H9 culture that displayed minimal cytopathic effect. The virus (168C) was now sensitive to neutralization by MN rgp120 vaccine sera and by MN-specific monoclonal antibodies and showed increased sensitivity to HIVIG and CD4-Ig. 168C encoded three amino acid changes in gp120, including one within the V3 loop (I-166-->R, I-282-->N, G-318-->R). MN-specific monoclonal antibodies bound equally to the surface of cells infected with either neutralization-resistant or -sensitive virus. The coincidence of changes in neutralization sensitivity with changes in cell tropism and cytopathic effect suggests a common underlying mechanism(s) acting through the whole of the envelope protein complex.

Evidence for a stem cell-specific repressor of Moloney murine leukemia virus expression in embryonal carcinoma cells

A negative regulatory element (NRE) spanning the tRNA primer-binding site (PBS) of Moloney murine leukemia virus (M-MuLV) mediates repression of M-MuLV expression specifically in embryonal carcinoma (EC) cells. We precisely defined the element by base-pair mutagenesis to an 18-base-pair segment of the tRNA PBS and showed that the element also restricted expression when moved upstream of the long terminal repeat. A DNA-binding activity specific for the M-MuLV NRE was detected in vitro by using crude EC nuclear extracts in exonuclease III protection assays. Binding was strongly correlated with repression in EC cells. Mutations within the NRE that relieved repression disrupted binding activity. Also, nuclear extracts prepared from permissive, differentiated EC cell cultures showed reduced binding activity for the NRE. These results indicate the presence of a stem cell-specific repressor that extinguishes M-MuLV expression via the NRE at the tRNA PBS.

Negative regulation of retrovirus expression in embryonal carcinoma cells mediated by an intragenic domain

An intragenic region spanning the tRNA primer binding site of a Moloney murine leukemia virus recombinant retrovirus was found to restrict expression specifically in embryonal carcinoma (EC) cells. When the inhibitory domain was present, the levels of steady-state RNA synthesized from integrated recombinant templates in stable cotransformation assays were reduced 20-fold in EC cells but not in C2 myoblast cells. Transient-cotransfection assays showed that repression of a template containing the EC-specific inhibitory component was relieved by an excess of specific competitor DNA. In addition, repression mediated by the inhibitory component was orientation independent. This evidence demonstrates the presence of a saturable, trans-acting negative regulatory factor(s) in EC cells and suggests that the interaction of the factor(s) with the intragenic inhibitory component occurs at the DNA level.

Proviral sequences that restrict retroviral expression in mouse embryonal carcinoma cells

Embryonal carcinoma (EC) cells are nonpermissive for retrovirus replication. Restriction of retroviral expression in EC cells was studied by using DNA transfection techniques. To investigate the activity of the Moloney murine leukemia virus (M-MuLV)enhancer and promoter sequences, the M-MuLV long terminal repeat and the defined long terminal repeat deletions were linked to neo structural gene sequences that encode resistance to the neomycin analog G418. Transient expression data and drug resistance frequencies support the findings that the M-MuLV enhancer is not active in EC cells but that promoter sequences are functional. In addition, a proviral DNA fragment that encodes the leader RNA sequence of a M-MuLV recombinant retrovirus was found to restrict expression specifically in EC cells. Deletion analysis of the leader fragment localized the inhibitory sequences to a region that spans the M-MuLV tRNA primer binding site. It is not known whether restriction occurs at a transcriptional or posttranscriptional level, but steady-state RNA levels in transient expression assays were significantly reduced.