Structure, genomic DNA typing, and kinetic characterization of the D allozyme of placental alkaline phosphatase (PLAP/ALPP)

The D allozyme of placental alkaline phosphatase (PLAP) displays enzymatic properties at variance with those of the common PLAP allozymes. We have deduced the amino acid sequence of the PLAP D allele by PCR cloning of its gene, ALPP. Two coding substitutions were found in comparison with the cDNA of the common PLAP F allele, i.e., 692C>G and 1352A>G, which translate into a P209R and E429G substitution. A single nucleotide primer extension (SNuPE) assay was developed using PCR primers that enable the amplification of a 1.9 kb PLAP fragment. Extension primers were then used on this PCR fragment to detect the 692C>G and 1352A>G substitution. The SNuPE assay on these two nucleotide substitutions enabled us to distinguish the PLAP F and D alleles from the PLAP S/I alleles. Functional studies on the D allozyme were made possible by constructing and expressing a PLAP D cDNA, i.e., [Arg209, Gly429]PLAP, into wild-type Chinese hamster ovary cells. We determined the k(cat) and K(m), of the PLAP S, F, and D allozymes using the non-physiological substrate p-nitrophenylphosphate at an optimal pH (9.8) as well as two physiological substrates, i.e., pyridoxal-5-phosphate and inorganic pyrophosphate at physiological pH (7.5). We found that the biochemical properties of the D allozyme of PLAP are significantly different from those of the common PLAP allozymes. These biochemical findings suggest that a suboptimal enzymatic function by the PLAP D allozyme may be the basis for the apparent negative selective pressure of the PLAP D allele. The development of the SNuPE assay will enable us to test the hypothesis that the PLAP D allele is subjected to intrauterine selection by examining genomic DNA from statistically informative population samples.     

Loss-of-Function Mutations in the ALPL Gene Presenting with Adult Onset Osteoporosis and Low Serum Concentrations of Total Alkaline Phosphatase

Hypophosphatasia (HPP) is a rare inherited disorder characterized by rickets and low circulating concentrations of total alkaline phosphatase (ALP) caused by mutations in ALPL. Severe HPP presents in childhood but milder forms can present in adulthood. The prevalence and clinical features of adult HPP are poorly defined. The aim of this study was to evaluate the prevalence and clinical significance of low serum total alkaline phosphatase (ALP) levels in a clinic-based population of adult osteoporotic patients. We searched for patients with low ALP in a cohort of 3285 patients referred to an osteoporosis clinic over a 10-year period and performed mutation screening of ALPL in those with low ALP (≤40 U/L) on two or more occasions. These individuals were matched with four clinic controls with a normal ALP. We also evaluated the prevalence of low ALP and ALPL mutations in 639 individuals from the general population from the same region. We identified 16/3285 (0.49%) clinic patients with low ALP and 14 (87.5%) had potentially pathogenic variants in ALPL. Eight of these individuals were heterozygous for mutations previously described in HPP and 2 were heterozygous for novel mutations (p.Arg301Trp and p.Tyr101X). These mutations were not found in clinic controls or in the general population. Eight patients with low ALP, including 4 with ALPL mutations, were treated with bisphosphonates for an average of 6.5 years. In these individuals, the rate of fractures during treatment was comparable to that in normal ALP clinic controls who were treated with bisphosphonates. We conclude that heterozygous loss-of-function mutations in ALPL are common in osteoporosis patients with low ALP. Further studies are required to determine how best these individuals should be treated. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.     

Klassifikation und Grading von Gliomen und Meningeomen

Zusammenfassung Gliome: Wir konnten zeigen, da? für übliche supratentorielle Gliome im Erwachsenenalter ein 2stufiger Grading-Ansatz mit alleiniger Unterscheidung eines niedrigen und hohen Malignit?tsgrads zu reproduzierbaren und prognostisch relevanten Informationen führt. Das entscheidende diagnostische Kriterium sowohl für High-grade-Astrozytome (WHO Glioblastome) als auch für anaplastische Oligodendrogliome und Oligoastroazytome sind Endothelhyperplasien bzw. -proliferate als Zeichen einer in Gang gekommenen Neoangiogenese. Diese ist in der Regel mit einer Kontrastmittelaufnahme in den bildgebenden Verfahren korreliert. Daher hat es sich sehr bew?hrt, wenn zur histopathologischen Untersuchung eines Gliomresektats bzw. -biopsats die neuroradiologischen Bilder (CCT, KST nativ und nach Kontrastmittelgabe) vorliegen oder zumindest das neuroradiologische Untersuchungsergebnis bekannt ist. Meningeome: Jene rezidivgef?hrdeten Meningeome, die sowohl feingeweblich als auch prognostisch eine Zwischenstellung zwischen üblichen und anaplastischen Meningeomen einnehmen, sind als sog. atypische Meningeome (WHO-Grad II) in die revidierte Fassung der WHO Klassifikation aufgenommen worden. Mit morphometrisch ermittelten kernfl?chenbezogenen Ki-67 Indizes konnte dieser intermedi?re Typ n?her eingegrenzt und histologisch besser definiert werden. Da rezidivgef?hrdete Meningeome als h?ufigste progressionsassoziierte Ver?nderung einen distalen Stückverlust am kurzen Arm eines Chromosoms 1 (1p-) zeigen, lie? sich eine Screening-Methode mit der gewebeunspezifischen Form der Alkalischen Phosphatase als Markerenzym etablieren. Die Diagnose eines Meningeoms vom intermedi?ren Typ bedeutet, da? engmaschigere postoperative Verlaufskontrollen zur frühzeitigen Erfassung eines „Rezidivs” erfolgen sollten.      

A Case of Vitamin D Deficiency without Elevation of Serum Alkaline Phosphatase in a Carrier of Hypophosphatasia

Elevated serum alkaline phosphatase (ALP) is a screening marker for the diagnosis of vitamin D deficiency, which may fail to be diagnosed if serum ALP is not elevated. Here, we describe a case of vitamin D deficiency without elevation of serum ALP. A 1-year-old Japanese girl was referred to our hospital for the evaluation of genu varum. Her serum intact PTH level was elevated, while her serum ALP level was normal. Furthermore, her serum 25-hydroxyvitamin D level was reduced, and her urine phosphoethanolamine (PEA) level was mildly elevated. ALPL gene analysis revealed she was a heterozygous carrier of hypophosphatasia (c.1559delT). Serum intact PTH and urine PEA evaluations were helpful for diagnosing vitamin D deficiency and hypophosphatasia carrier status, respectively. Therefore, the possibility of vitamin D deficiency without elevation of serum ALP should be considered.     

Evaluation of Vitamin D (25OHD), Bone Alkaline Phosphatase (BALP), Serum Calcium,Serum Phosphorus,Ionized Calcium in Patients with Mandibular Third Molar Impaction. An Observational Study

The aim of this study was to evaluate the levels of vitamin D (25OHD) and other bone biomarkers in patients with third molar impaction (TMI). Thirty males and 30 females with unilateral or bilateral impacted mandibular third molar, and 15 males and 15 females as a control group (CG) were recruited. Rx-OPT was used to evaluate dental position and Pederson index to measure the difficulty of the intervention. Bone biomarkers were measured through blood venous sample in TMI group and CG. Mann-Whitney test, Pearson’s correlation coefficient, linear regression model were used to compare the different parameters in the two groups. 25OHD showed lower values in TMI group than in CG (p < 0.05) with values significantly lower in bilateral impaction (p < 0.05). Pearson’s coefficient for 25OHD presented a negative correlation with the Pederson index (ρ = −0.75). Bone alkaline phosphatase (BALP) showed significantly lower dosage in TMI group than CG (p = 0.02), Pearson’s coefficient for BALP presented a negative correlation with the Pederson index. Serum calcium, serum phosphorus, ionized calcium levels in TMI and CG groups were similar and Mann-Whitney test did not significantly differ between TMI and CG. TMI could be a sign of vitamin D deficiency and of low BALP levels that should be investigated.     

Indole-3-carbinol (I3C) exhibits inhibitory and preventive effects on prostate tumors in mice.

Prostate cancer (PC) is the most commonly diagnosed malignancy for men in Western countries. Research showed that cruciferous vegetables containing indole derivatives were involved in cancer prevention. This study was designed to investigate the effect of indole-3-carbinol (I3C) in cell lines and on PC tumor growth in mice when given as a therapeutic and as a preventive treatment. The effect in vitro of 13C on the viability, proliferation and apoptosis of mouse PC cell line TRAMP-C2 and on bovine capillary endothelial (BCE) cells was examined using MTT, BrdU and FACS analyses. The effect of I3C (20 mg/kg body weight) as both a therapeutic and a preventive treatment on the growth of PC cells, inoculated subcutaneously in C57BL/6 mice, was evaluated using tumor volume measurements and immunohistochemistry. I3C decreased the proliferation rate in 3-folds (staining to Ki-67), and promoted apoptosis (staining with caspase 3). I3C, injected intraperitonially (I.P.), significantly inhibited the tumor growth (a 78% decrease in tumor volume) and affected the angiogenesis process by decreasing the microvessel density (CD31 endothelial marker) and complexity. I3C has a significant inhibitory effect on PC cells in vitro and in vivo, and offers a potential usage as both preventive and therapeutic agent for humans.     

组织非特异性碱性磷酸酶基因突变与低磷酸酶血症：2个新突变位点

目的：对2例低磷酸酶血症（HPP）患者及家系进行分析和基因突变检测,拓展国人HPP致病基因库,探讨HPP的致病机制。方法对HPP家系先证者和其父母进行生化指标[血常规、肝肾功能、碱性磷酸酶（ALP）、甲状旁腺素（PTH）、钙、磷等]和骨密度检测。同时对所有研究对象进行alkaline phospatase,live/bone/kidney（ALPL）基因全部12个外显子和外显子内含子交界区直接测序。结果来自家系1的先证者为36岁成年男性,身高131.0cm,体重35.0kg。X线提示多发性胸腰椎骨折和骨盆畸形,生化检测示血清ALP27U/L。测序发现ALPL基因6号外显子532位杂合突变（c.532T＞C）,致ALPL成熟多肽中酪氨酸被组氨酸替代。该先证者母亲身高140.5cm,体重39.5kg,血清ALP30U/L,基因测序证明也是该杂合突变携带者。来自家系2的先证者5岁,其外祖父母为近亲结婚。该患儿身高100.0cm,体重18kg。血清ALP55U/L[低于同龄儿童正常范围（＜10岁）75～344U/L],牙齿发育不良并脱落,有左股骨中下端骨折史。测序发现该患儿存在ALPL基因2个错义突变,其中9号外显子c.871G＞A突变。4号外显子269位突变（c.269A＞G）是一个新的错义突变,该突变导致成熟ALPL多肽中天冬氨酸被甘氨酸所替代。该患儿母亲亦是4号外显子c.269A＞G错义突变携带者,但其生化指标正常,无骨骼和牙齿异常。结论ALPL基因6号外显子c.532T＞C突变和4号外显子c.269A＞G突变是以往未曾报道过的新错义突变,为上述2例HPP患者致病基因。     

5 例低磷酸酯酶症患儿临床及遗传学分析

目的总结低磷酸酯酶症(HPP)的临床及遗传学特点。方法回顾分析5 例HPP患儿的临床资料,以及患儿及其亲属的外周血高通量测序及Sanger验证结果。结果 5例患儿均有骨骼矿化不良以及血清碱性磷酸酶降低,3例伴有惊厥等神经系统症状。5例HPP患儿高通量测序共发现ALPL6个突变位点,c.346GA(p.A116T)、c.1097至c.1099del CCT复合杂合突变(p.T366_S367deli)、c.1014至c.1015ins G(p.H338fs)、c.1446CA(p.482HQ)复合杂合突变、c.920CT(p.P307L)、c.883AG(p.M295V),其中c.1014_c.1015ins G、c.1097_c.1099del CCT、c.1446CA为首次报道,蛋白质结构预测均为可能有害,ACMG评级为可能致病。结论确诊5例HPP患儿,发现 3种新型突变,丰富了人类ALPL基因突变数据库。