[Clinical phenotypic and genotypic analysis of 5 pediatric patients with β-ketothiolase deficiency]

Objective: To summarize the clinical and genetic characteristics of children with β-ketothiolase deficiency (BKTD). Methods: The clinical characteristics, biochemical, markers detected by tandem mass spectrometry (MS/MS) and gas chromatography-mass spectrometry (GC/MS), as well as the variants in ACAT1 gene among 5 children with BKTD in Children's Hospital of Chongqing Medical University between October 2018 and December 2022 were retrospectively analyzed. Results: The onset age of the disease in 5 patients (4 males and 1 female) ranged from 9.7 to 28.0 months. During the acute phase, severe metabolic acidosis was observed with a pH of 6.9-7.1, as well as hypoglycaemia (2.3-3.4 mmol/L) and positive urinary ketone bodies (+-++++). Blood levels of methylcrotonyl carnitine, methylmalonyl carnitine and malonyl carnitine were 0.03-0.42, 0.34-1.43 and 0.83-3.53 μmol/L respectively and were significantly elevated. Urinary 2-methyl-3-hydroxybutyric acid was 22-202 and 3-hydroxybutyric acid was 4-6 066, both were higher than the normal levels. Methylcrotonylglycine was mild elevated (0-29). The metabolites detected by MS/MS and GC/MS were significantly reduced after treatment. Analysis of ACAT1 gene mutation was performed in 5 children. Most variants were missense (8/9). Four previously unreported variants were identified: c.678G>T (p.Trp226Cys), c.302A>G (p.Gln101Arg), c.627_629dupTGA (p.Asn209_Glu210insAsp) and c.316C>T (p.Gln106Ter), the first 2 variants were predicted to be damaging by SIFT, PolyPhen-2 and Mutation Taster software. c.316C>T (p.Gln106Ter) is a nonsense variant. Conclusions: β-ketothiolase deficiency is relatively rare, lacks specific clinical manifestations, however severe metabolic acidosis, hypoglycemia, and ketosis during the acute onset were consistent findings. Missense mutations in the ACAT1 gene are common genetic causes of β-ketothiolase deficiency.

Identification of the chitinase genes from the diamondback moth, Plutella xylostella

Chitinases have an indispensable function in chitin metabolism and are well characterized in numerous insect species. Although the diamondback moth (DBM) Plutella xylostella, which has a high reproductive potential, short generation time, and characteristic adaptation to adverse environments, has become one of the most serious pests of cruciferous plants worldwide, the information on the chitinases of the moth is presently limited. In the present study, using degenerated polymerase chain reaction (PCR) and rapid amplification of cDNA ends-PCR strategies, four chitinase genes of P. xylostella were cloned, and an exhaustive search was conducted for chitinase-like sequences from the P. xylostella genome and transcriptomic database. Based on the domain analysis of the deduced amino acid sequences and the phylogenetic analysis of the catalytic domain sequences, we identified 15 chitinase genes from P. xylostella. Two of the gut-specific chitinases did not cluster with any of the known phylogenetic groups of chitinases and might be in a new group of the chitinase family. Moreover, in our study, group VIII chitinase was not identified. The structures, classifications and expression patterns of the chitinases of P. xylostella were further delineated, and with this information, further investigations on the functions of chitinase genes in DBM could be facilitated.

Preparation and photocatalytic property of TiO2-Fe3O4 core-shell nanoparticles

Titanium dioxide is an attractive photocatalytic material with a wide band gap which can be applied in chemical processes to degrade organic compounds. When TiO2 nanoparticles are dispersed in water solution in suspended state they possess high photocatalytic activity, resulting in effectively degrading the hazardous compounds in wastewater. But when the TiO2 nanoparticles are used in suspension state, it is very difficult to get them back and make them reuse, which would limit their application due to the cost. Here, we report the preparation of reusable TiO2 composite nanoparticles with a core-shell structure, which consist of a nanosized Fe3O4 core and the encapsulated TiO2 shell. The experimental result shows that these nanoparticles can be used in suspended state and exhibit high photocatalytic activity. In addition, the photocatalytic nanoparticles with core-shell structure can be easily withdrawn with a magnetic field.

[Determination of plasma homocysteine by high performance liquid chromatography with fluorescence detection]

This article report a highly sensitive method specific for the determination of homocysteine in plasma by high performance liquid chromatography with fluorescence detection. Half mL plasma with 100 microL 0.11 mol/L sodium borohydride in 50 mmol/L Tris-HCl (pH 9.0) was kept at 30 degrees C for 30 min, and then 0.5 mL 0.5 mol/L perchloric acid was added. After the mixture was kept at room temperature for 10 min and centrifuged at 15,000 r/min for 10 min, 0.5 mL aliquots of the supernatant solution was pipetted into another vial containing 0.1 mL 3 mmol/L Bromobimane in 1.0 mol/L Na2EDTA (pH 7.0) and 0.7 mL of 90 mmol/L ammonium bicarbonate buffer containing 1.43 mol/L Na2EDTA, pH 8.0. The content was mixed, kept at 37 degrees C for 30 min and centrifuged at 15,000 r/min for 10 min. Then 10 microL aliquots of the supernatant solution was injected into a high performance liquid chromatograph with fluorescence detector. The chromatographic conditions were as follows: an ODS column (4.6 mm i.d. x 150 mm, 5 microns), was eluted with a flow rate of 1.0 mL/min. The fluorescence detector was operated at lambda ex 365 nm and lambda em 475 nm. Mobile phase frompump A was 3% methanol containing 0.25% acetic acid. In gradient elution program the methanol from pump B was as follows: 0-8 min, 5%; 8-15 min, 5%-12%; 15-20 min, 12%; 20-30 min, 12%-20%; 30-32 min, 20%; 32-35 min, 20%-100%; 35-40 min, 100%; 40-43 min, 100%-5%; 43-45 min, 5%. The method proved to be linear in the range of 2.5-80.0 mumol/L with a regression coefficient of 0.9988. The minimum detection limit was 0.5 mumol/L, the recoveries were 94.0%-112.0%, and the RSD values were less than 5.6%.

Studies on peripheral T lymphocyte subsets in patients with autoimmune thyroid diseases

Peripheral T lymphocyte subsets in 60 cases of Graves' disease (GD) and 16 cases of Hashimoto's thyroiditis (HT) were determined by the use of OKT monoclonal antibodies (McAb). The results showed that in both diseases OKT3 cells (total T cells) and OKT8 cells (suppressor T cells, TS cells) were lower and the ratio of OKT4 cells (helper T cells, TH cells) OKT8 cells was much higher than those in normal controls. GD patients who were treated with antithyroid drugs (ATD) and whose serum T3, T4 recovered to normal, could be further divided into subgroups of high OKT4/OKT8 cell ratio and of normal ratio. The pathogenesis, treatment and relapse of autoimmune thyroid diseases (AITD) were discussed in this paper on the basis of the results.

Augmentation of IL 1-induced fibroblast PGE2 production by a urine-derived IL 1 inhibitor

IL 1, a monocyte-derived cytokine, has potent biologic effects in a variety of target tissues. The existence of naturally occurring inhibitors of IL 1 activity has been recently described; these inhibitors blocked one IL 1 effect: stimulation of thymocyte responses to mitogens. We examined the effect of one well-characterized inhibitor of IL 1, isolated from the urine of febrile patients, on a second IL 1 effect, stimulation of fibroblast PGE synthesis. In this system, purified preparations of the urinary inhibitor that completely blocked murine thymocyte proliferative responses to mitogen failed to block PGE synthetic responses to IL 1. Rather, inhibitor preparations markedly enhanced fibroblast PGE synthetic responses to IL 1. When partially purified inhibitor preparations were fractionated by ion exchange chromatography, inhibitory activity for the IL 1 effect on thymocytes and PGE stimulatory activity co-eluted. Augmentation of the IL 1-induced PGE response was seen with both low (1:1 unit) and high (400:1) ratios of inhibitor to IL 1. Inhibitor preparations alone did not stimulate fibroblast PGE synthesis. The augmentation of fibroblast PGE synthesis by inhibitor preparations was not due to contaminating endotoxin. Active inhibitor preparations contained less than 15 pg of endotoxin/U activity, and the PGE stimulatory effect was not blocked by the addition of polymyxin B, whereas polymyxin B reversed the effects of exogenous endotoxin. It appears that the inhibition of IL 1 effects by naturally occurring inhibitors may have target cell and/or functional specificity.

Augmentation of IL 1-induced fibroblast PGE2 production by a urine-derived IL 1 inhibitor

IL 1, a monocyte-derived cytokine, has potent biologic effects in a variety of target tissues. The existence of naturally occurring inhibitors of IL 1 activity has been recently described; these inhibitors blocked one IL 1 effect: stimulation of thymocyte responses to mitogens. We examined the effect of one well-characterized inhibitor of IL 1, isolated from the urine of febrile patients, on a second IL 1 effect, stimulation of fibroblast PGE synthesis. In this system, purified preparations of the urinary inhibitor that completely blocked murine thymocyte proliferative responses to mitogen failed to block PGE synthetic responses to IL 1. Rather, inhibitor preparations markedly enhanced fibroblast PGE synthetic responses to IL 1. When partially purified inhibitor preparations were fractionated by ion exchange chromatography, inhibitory activity for the IL 1 effect on thymocytes and PGE stimulatory activity co-eluted. Augmentation of the IL 1-induced PGE response was seen with both low (1:1 unit) and high (400:1) ratios of inhibitor to IL 1. Inhibitor preparations alone did not stimulate fibroblast PGE synthesis. The augmentation of fibroblast PGE synthesis by inhibitor preparations was not due to contaminating endotoxin. Active inhibitor preparations contained less than 15 pg of endotoxin/U activity, and the PGE stimulatory effect was not blocked by the addition of polymyxin B, whereas polymyxin B reversed the effects of exogenous endotoxin. It appears that the inhibition of IL 1 effects by naturally occurring inhibitors may have target cell and/or functional specificity.