Increased tracheostomy rates in head and neck cancer surgery during the COVID-19 pandemic

Surgical practice during the coronavirus disease 2019 (COVID-19) pandemic has changed significantly, without supporting data. With increasing experience, a dichotomy of practice is emerging, challenging existing consensus guidelines. One such practice is elective tracheostomy. Here, we share our initial experience of head and neck cancer surgery in a COVID-19 tertiary care centre, emphasizing the evolved protocol of perioperative care when compared to pre-COVID-19 times. This was a prospective study of 21 patients with head and neck cancers undergoing surgery during the COVID-19 pandemic, compared to 193 historical controls. Changes in anaesthesia, surgery, and operating room practices were evaluated. A strict protocol was followed. One patient tested positive for COVID-19 preoperatively. There was a significant increase in pre-induction tracheostomies (28.6% vs 6.7%, P = 0.005), median hospital stay (10 vs 7 days, P = 0.001), and postponements of surgery (57.1% vs 27.5%, P = 0.01), along with a significant decrease in flap reconstructions (33.3% vs 59.6%, P = 0.03). There was no mortality and no difference in postoperative morbidity. No healthcare personnel became symptomatic for COVID-19 during this period. Tracheostomy is safe during the COVID-19 pandemic and rates have increased. Despite increased rescheduling of surgeries and longer hospital stays, definitive cancer care surgery has not been deferred and maximum patient and healthcare worker safety has been ensured.

WWOX mRNA expression profile in epithelial ovarian cancer supports the role of WWOX variant 1 as a tumour suppressor, although the role of variant 4 remains unclear

WWOX is a candidate tumour suppressor gene that exhibits LOH or homozygous deletion in several tumour types. As well as the predominant full-length transcript (variant 1) there also exist alternatively spliced transcripts found previously only in malignant tissue. It has been suggested that proteins encoded by these variants may interfere with normal WWOX function in a dominant negative fashion. The most prevalent alternate transcript demonstrated in ovarian cancer is variant 4, which lacks exons 6-8. Here, we report the first comparison of the mRNA expression of WWOX variants 1 and 4 in human ovarian tumours and normal ovaries, and correlate expression with clinical data. We demonstrate significantly lower WWOX variant 1 expression in tumours than in normal ovaries. This reduction was not associated with any specific clinical subgroup. Variant 4 was expressed at low levels, and significantly associated with high grade and advanced stage ovarian cancer. Furthermore, tumours co-expressing variant 4 and relatively high levels of variant 1 showed significantly worse survival than tumours expressing variant 1 alone. However, variant 4 was also frequently identified in non-malignant ovarian tissue. These results support the role of WWOX variant 1 as a suppressor of ovarian tumourigenesis, but the role of variant 4 remains speculative.

Reconstitution of a functional core polycomb repressive complex

The opposing actions of polycomb (PcG) and trithorax group (trxG) gene products maintain essential gene expression patterns during Drosophila development. PcG proteins are thought to establish repressive chromatin structures, but the mechanisms by which this occurs are not known. Polycomb repressive complex 1 (PRC1) contains several PcG proteins and inhibits chromatin remodeling by trxG-related SWI/SNF complexes. We have defined a functional core of PRC1 by reconstituting a stable complex using four recombinant PcG proteins. One subunit, PSC, can also inhibit chromatin remodeling on its own. These PcG proteins create a chromatin structure that has normal nucleosome organization and is accessible to nucleases but excludes hSWI/SNF.

Mechanisms of transcriptional memory

How can the same gene remember that it is 'off' in one cell lineage and 'on' in another? Studies of how homeotic genes are regulated in Drosophila melanogaster have uncovered a transcriptional maintenance system, encoded by the Polycomb and trithorax group genes, that preserves expression patterns across development. Here we try to formulate a broad framework for the types of molecular mechanism used by the Polycomb and trithorax proteins.

Cellular and molecular determinants of sympathetic neuron development

The development of the sympathetic nervous system can be divided into three overlapping stages. First, the precursors of sympathetic neurons arise from undifferentiated neural crest cells that migrate ventrally, aggregate adjacent to the dorsal aorta, and ultimately differentiate into catecholaminergic neurons. Second, cell number is refined during a period of cell death when neurotrophic factors determine the number of neuronal precursors and neurons that survive. The final stage of sympathetic development is the establishment and maturation of synaptic connections, which for sympathetic neurons can include alterations in neurotransmitter phenotype. Considerable progress has been made recently in elucidating the cellular and molecular mechanisms that direct each of these developmental decisions. We review the current understanding of each of these, focusing primarily on events in the peripheral nervous system of rodents.

A sweat gland-derived differentiation activity acts through known cytokine signaling pathways

The sympathetic innervation of sweat glands undergoes a target-induced noradrenergic to cholinergic/peptidergic switch during development. Similar changes are induced in cultured sympathetic neurons by sweat gland cells or by one of the following cytokines: leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), or cardiotrophin-1 (CT-1). None of these is the sweat gland-derived differentiation activity. LIF, CNTF, and CT-1 act through the known receptors LIF receptor beta (LIFRbeta) and gp130 and well defined signaling pathways including receptor phosphorylation and STAT3 activation. Therefore, to determine whether the gland-derived differentiation activity was a member of the LIF/CNTF cytokine family, we tested whether it acted via these same receptors and signal cascades. Blockade of LIFRbeta inhibited the sweat gland differentiation activity in neuron/gland co-cultures, and extracts of gland-containing footpads stimulated tyrosine phosphorylation of LIFRbeta and gp130. An inhibitor (CGX) of molecules that bind the CNTFRalpha, which is required for CNTF signaling, did not affect the gland-derived differentiation activity. Soluble footpad extracts induced the same changes in NBFL neuroblastoma cells as LIF and CNTF, including increased vasoactive intestinal peptide mRNA, STAT3 dimerization, and DNA binding, and stimulation of transcription from the vasoactive intestinal peptide cytokine-responsive element. Thus, the sweat gland-derived differentiation activity uses the same signaling pathway as the neuropoietic cytokines, and is likely to be a family member.

CNTF and LIF are not required for the target-directed acquisition of cholinergic and peptidergic properties by sympathetic neurons in vivo

During development, the sympathetic innervation of two targets, sweat glands and periosteum, changes the neurotransmitters it expresses from noradrenaline to acetylcholine and vasoactive intestinal peptide (VIP). The target-derived molecules that induce, these changes have not been identified. Neuropoietic cytokines, including ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF), induce the same phenotypic changes in sympathetic neurons in vitro as sweat glands and periosteum do in vivo, raising the possibility that one of these factors mediates induction of cholinergic traits and VIP by these target tissues. Because CNTF and LIF have overlapping functions and signalling pathways, they could act interchangeably or in concert to influence neurotransmitter expression. To determine whether CNTF or CNTF and LIF together are responsible for the induction of cholinergic and peptidergic function in vivo, we analyzed the neurotransmitter properties of sweat gland innervation in mice lacking CNTF or CNTF and LIF. We find that, as in wild-type mice, gland innervation in mice lacking one or both molecules appropriately expresses cholinergic properties and VIP immunoreactivity. Furthermore, footpads of mice lacking one or both genes contain choline acetyltransferase activity comparable to that of wild-type mice, and CNTF- or CNTF/LIF-deficient mice possess the normal complement of active sweat glands. We analyzed the innervation of a second, recently identified cholinergic sympathetic target, the periosteum, which is the connective tissue surrounding bone. Periosteal innervation of mice lacking CNTF, LIF, or both, like that of wild-type mice, is immunoreactive for the vesicular acetylcholine transporter, a recently identified cholinergic marker, and VIP. These results provide evidence that neither CNTF, LIF, nor a combination of the two are required for the developmental change from noradrenergic to cholinergic function that occurs in sympathetic innervation of sweat glands and periosteum.

The role of acetylcholine in regulating secretory responsiveness in rat sweat glands

While retrograde regulation of neuronal development by target-derived factors in the autonomic nervous system is well established, the importance of anterograde influences on target development is unclear. Previous studies suggest that sympathetic innervation of sweat glands plays a critical role in the acquisition and maintenance of their secretory function. To define the signal(s) responsible, we disrupted muscarinic cholinergic transmission in developing and adult rats. Treatment of young rats with the nonselective antagonist, atropine, or an antagonist selective for the glandular muscarinic subtype, 4-DAMP, delayed the development of secretory responsiveness. Treatment of adult animals with atropine caused its loss. Further, following denervation, treatment with the muscarinic agonist, pilocarpine, largely preserved responsiveness while untreated animals lost function. Thus, acetylcholine, whose presence in sweat gland innervation is retrogradely specified by developmental interactions with the target tissue, in turn plays an important role in inducing and maintaining target tissue responsiveness through muscarinic receptor activation.