Timing of dental extractions in patients undergoing radiotherapy and the incidence of osteoradionecrosis: a systematic review and meta-analysis

This systematic review aimed to examine whether the incidence of osteonecrosis differed between patients who have dental extractions before or after radiotherapy (RT). The reported incidence of osteoradionecrosis (ORN) of the jaws following RT to the head and neck varies widely in the literature. Currently, for patients with head and neck cancer there are no universally accepted guidelines on the optimal timing of dental surgery relative to RT to minimise incident ORN. A literature review was conducted using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) criteria. A search of PubMed, EMBASE, Evidence-Based Medicine, and Web of Science databases targeted literature published up to and including 10 April 2020. Two independent reviewers assessed studies for eligibility against inclusion criteria. An assessment of bias was conducted for each of the included studies and relevant data extracted. A meta-analysis was undertaken using the statistical methods described. Twenty-four of 708 studies were included. They were heterogeneous and included a wide variation of RT methods, head and neck malignancies, and comorbidities. While some concluded that the incidence of ORN was dependent on the timing of dental extractions in relation to RT, with regard to the risk of its development, others reported additional factors such as age, comorbidities, extent of surgical resection, and dose and field of radiation, as more important predictors than timing. In many there was consistent lack of detail around the timing of dental procedures in relation to the delivery of RT. From 21 studies including 36,294 patients, of whom 14,389 had extractions before RT, the pooled incidence of ORN was 5.5% (95% CI: 2.1% to 10.1%). Significant heterogeneity was found in Cochran’s Q-test (p < 0.001) and Higgins I² = 98.0%. From 21 studies including 37,805 patients, of whom 6030 had extractions after RT, the pooled incidence of ORN was 5.3% (95% CI: 2.9% to 8.2%). Significant heterogeneity was found in Cochran’s Q-test (p < 0.001) and Higgins I² = 80.0%. There was no statistically significant difference between these two groups (random-effects model Q=0.12, p=0.73). Large, longitudinal studies with a priori-specified methods are needed to identify, recruit, and prospectively follow patients with head and neck cancer for the onset of ORN after dental surgery. This will allow clinical guidelines to be established to assist clinicians to plan treatment when extractions are indicated in patients undergoing RT to the head and neck.     

Molecular characterization of human factor XSan Antonio

Enzymatic amplification technique was used to isolate all eight exons and sequences around the splice junctions, putative promoter, and polyadenylation sites of human factor X DNA from a patient with factor X deficiency. Two genetic changes in factor X have been observed in this patient. The patient is most likely a compound heterozygote since there is only 14% activity associated with factor X. A point mutation that resulted in the substitution of cysteine (TGC) for arginine (CGC) at amino acid 366 was found in exon VIII of one allele of the factor X gene. This mutation, which occurs in the catalytic domain, can affect the formation of a disulfide bridge and thus could result in a reduction in factor X activity. Sequencing all the regions revealed a second mutation: a deletion of one nucleotide (TCCT to TCT) in exon VII that would cause a frame shift at amino acid 272 followed by termination. We have also shown that the point mutation in exon VIII creates an ApaL1 restriction site and destroys the HinP1 site. Enzymatic DNA amplification followed by restriction digestion provides a quick, reliable, and sensitive method for carrier detection and antenatal diagnosis in affected kindreds. This is the first characterization of factor X deficiency at the molecular level. We propose to name this mutation Factor XSan Antonio.     

A radioreceptor assay for quantitating plasma factor VIII/von Willebrand's protein

A sensitive and precise radioreceptor assay for determining plasma levels of human factor VIII/von Willebrand's factor (FVIII/vWF) has been developed by taking advantage of the FVIII/vWF receptor sites on human platelets. Paraformaldehyde-fixed platelets, which were processed and then stored, retained FVIII/vWF binding activity and therefore could be used as a convenient source of receptors. The human plasma samples to be tested were initially filtered on 4% agarose columns to concentrate the FVIII/vWF protein in the void volume and to remove the factor(s) that interferes with the assay. The percent recovery of FVIII/vWF in the pooled eluent was measured by the recovery of added trace 125I-FVIII/vWF. The coefficients of intra- and interassay variation were 6% and 10%, respectively. The plasma FVIII/vWF concentrations determined by the assay for pooled normal plasma, hemophilia A plasma, and plasmas from two patients with von Willebrand's disease were 16.3 +/- 0.5, 52.6 +/- 1.5, 6.8 +/- 0.8, and 3.2 +/- 0.2 microgram/ml, respectively. The range of plasma FVIII/vWF concentrations varied between 8.3 microgram/ml and 24.9 microgram/ml for 10 normal adults. The plasma FVIII/vWF concentrations determined by the radioreceptor assay correlated well with levels measured by the ristocetin-induced platelet aggregation method, thus demonstrating the functional relevancy of the radioreceptor assay for plasma FVIII/vWF.     

Myeloid Mixed Lineage Kinase 3 Contributes to Chronic Ethanol-Induced Inflammation and Hepatocyte Injury in Mice

Proinflammatory activity of hepatic macrophages plays a key role during progression of alcoholic liver disease (ALD). Since mixed lineage kinase 3 (MLK3)-dependent phosphorylation of JNK is involved in the activation of macrophages, we tested the hypothesis that myeloid MLK3 contributes to chronic ethanol-induced inflammatory responses in liver, leading to hepatocyte injury and cell death. Primary cultures of Kupffer cells, as well in vivo chronic ethanol feeding, were used to interrogate the role of MLK3 in the progression of liver injury. Phosphorylation of MLK3 was increased in primary cultures of Kupffer cells isolated from ethanol-fed rats compared to cells from pair-fed rats. Kupffer cells from ethanol-fed rats were more sensitive to LPS-stimulated cytokine production; this sensitization was normalized by pharmacological inhibition of MLK3. Chronic ethanol feeding to mice increased MLK3 phosphorylation robustly in F4/80⁺ Kupffer cells, as well as in isolated nonparenchymal cells. MLK3^−/− mice were protected from chronic ethanol-induced phosphorylation of MLK3 and JNK, as well as multiple indicators of liver injury, including increased ALT/AST, inflammatory cytokines, and induction of RIP3. However, ethanol-induced steatosis and hepatocyte apoptosis were not affected by MLK3. Finally, chimeric mice lacking MLK3 only in myeloid cells were also protected from chronic ethanol-induced phosphorylation of JNK, expression of inflammatory cytokines, and increased ALT/AST. MLK3 expression in myeloid cells contributes to phosphorylation of JNK, increased cytokine production, and hepatocyte injury in response to chronic ethanol. Our data suggest that myeloid MLK3 could be targeted for developing potential therapeutic strategies to suppress liver injury in ALD patients.Key words: Alcoholic liver disease (ALD), Kupffer cells, Necroptosis, Toll-like receptor 4 (TLR4), Cytokines