Effect of COVID-19 on outpatient services in patients with aortovascular disease: a UK multicentre study.

INTRODUCTION: The SARS-CoV-2 coronavirus disease 2019 (COVID-19) pandemic has disrupted healthcare services worldwide. Outpatient services have necessarily been restructured to accommodate COVID-19 patients and to maintain social distancing measures. The aim of our study was to investigate how the COVID-19 pandemic has affected outpatient healthcare provision for patients with aortovascular disease. METHODS: In this prospective study, a standardised proforma was circulated to seven aortic centres in the UK. Data on outpatient encounters were collected from March to July 2020. Captured data included demographic details, disease pattern, type of encounter (face-to-face, video or telephone), clinic outcome and availability of imaging. RESULTS: A total of 632 patients were included in the study, including 164 (25.9%) new referrals. In this cohort, clinic settings have shifted towards remote consultations, with 424 (67.1%) patients undergoing telephone appointments. Over a third of new patients (34.8%) had a delay in diagnostic tests, which might be attributable to the indirect effects of COVID-19. A total of 102 (16.1%) patients were added to a surgical waiting list following clinic. CONCLUSIONS: To the best of our knowledge, this is the largest study of outpatient activity during the COVID-19 pandemic in patients with aortovascular disease. We demonstrate how the speciality has adapted to accommodate government-endorsed changes in healthcare provision, and question how COVID-19 may have affected access to diagnostics. Finally, we discuss how COVID-19 will affect patients added to surgical waiting lists.

Low immunogenicity in non-small cell lung cancer; do new developments and novel treatments have a role?

Approximately 1.6 million new cases of lung cancer are diagnosed annually (Jemal et al. CA: A Cancer Journal for Clinicians, 61, 69-90, 2011) and it remains the leading cause of cancer-related mortality worldwide. Despite decades of bench and clinical research to attempt to improve outcome for locally advanced, good performance status patients, the 5-year survival remains less than 15 % (Molina et al. 2008). Immune checkpoint inhibitor (ICH) therapies have shown a significant promise in preclinical and clinical trails to date in the treatment of non-small cell lung cancer (NSCLC). The idea of combining these systemic immune therapies with local ablative techniques is one that is gaining momentum. Electrochemotherapy (ECT) is a unique atraumatic local therapy that has had very promising objective response rates and a number of advantages including but not limited to its immunostimulatory effects. ECT in combination with ICHs offers a novel approach for dealing with this difficult disease process.

Phrenic nerve block as a novel adjunct to the local treatment of bronchopleural fistula.

Bronchopleural fistula (BPF) is a life threatening complication after pneumonectomy with an incidence of about 2-5% and a mortality rate of up to 50%. Topical treatment such as fibrin glue has been previously described with limited success. We present a novel case in which blocking the phrenic nerve assisted in a successful topical closure of the BPF.

Regulation of synaptic strength by sphingosine 1-phosphate in the hippocampus.

Although the hippocampus is a brain region involved in short-term memory, the molecular mechanisms underlying memory formation are not completely understood. Here we show that sphingosine 1-phosphate (S1P) plays a pivotal role in the formation of memory. Addition of S1P to rat hippocampal slices increased the rate of AMPA receptor-mediated miniature excitatory postsynaptic currents (mEPSCs) recorded from the CA3 region of the hippocampus. In addition long-term potentiation (LTP) observed in the CA3 region was potently inhibited by a sphingosine kinase (SphK) inhibitor and this inhibition was fully reversed by S1P. LTP was impaired in hippocampal slices specifically in the CA3 region obtained from SphK1-knockout mice, which correlates well with the poor performance of these animals in the Morris water maze test. These results strongly suggest that SphK/S1P receptor signaling plays an important role in excitatory synaptic transmission in the CA3 region of hippocampus and has profound effects on hippocampal function such as spatial learning.

Regulation of mammalian phospholipase D2: interaction with and stimulation by G(M2) activator.

We have previously reported that a heat-stable activator for ganglioside metabolism, G(M2) activator, potently stimulates ADP-ribosylation factor (ARF)-dependent phospholipase D (PLD) activity (presumably PLD1) in an in vitro system [Nakamura, Akisue, Jinnai, Hitomi, Sarkar, Miwa, Okada, Yoshida, Kuroda, Kikkawa and Nishizuka (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 12249-12253]. However, little is known about the regulation of PLD2. In the present studies we have investigated the regulation of PLD2 by G(M2) activator and various other regulators including ARF. PLD2 was potently stimulated in vitro by G(M2) activator in a time- and dose-dependent manner. Neither ARF nor protein kinase C caused any significant changes in PLD2 activity. Importantly, PLD2 responsiveness to ARF was greatly enhanced by G(M2) activator, suggesting a possible role for G(M2) activator as a coupling factor. G(M2) activator was also demonstrated to physically associate with PLD2 in a stoichiometric manner. Further, PMA stimulation of COS-7 cells overexpressing both G(M2) activator and PLD2 resulted in a marked increase in the association of the two molecules. Interestingly, ARF association with PLD2 was greatly increased by G(M2) activator. Moreover, G(M2) activator enhanced PMA-induced PLD activity in a synergistic manner with ARF in streptolysin-O-permeabilized, cytosol-depleted HL-60 cells, suggesting that G(M2) activator may regulate PLD in a concerted manner with other factors, including ARF, inside the cells.

The disaggregation theory of signal transduction revisited: further evidence that G proteins are multimeric and disaggregate to monomers when activated.

We have compared the sedimentation rates on sucrose gradients of the heterotrimeric GTP-binding regulatory (G) proteins Gs, G(o), Gi, and Gq extracted from rat brain synaptoneurosomes with Lubrol and digitonin. The individual alpha and beta subunits were monitored with specific antisera. In all cases, both subunits cosedimented, indicating that the subunits are likely complexed as heterotrimers. When extracted with Lubrol all of the G proteins sedimented with rates of about 4.5 S (consistent with heterotrimers) whereas digitonin extracted 60% of the G proteins with peaks at 11 S; 40% pelleted as larger structures. Digitonin-extracted Gi was cross-linked by p-phenylenedimaleimide, yielding structures too large to enter polyacrylamide gels. No cross-linking of Lubrol-extracted Gi occurred. Treatment of the membranes with guanosine 5'-[gamma-thio]triphosphate and Mg2+ yielded digitonin-extracted structures with peak sedimentation values of 8.5 S--i.e., comparable to that of purified G(o) in digitonin and considerably larger than the Lubrol-extracted 2S structures representing the separated alpha and beta gamma subunits formed by the actions of guanosine 5'-[gamma-thio]triphosphate. It is concluded that the multimeric structures of G proteins in brain membranes are at least partially preserved in digitonin and that activation of these structures in membranes yields monomers of G proteins rather than the disaggregated products (alpha and beta gamma complexes) observed in Lubrol. It is proposed that hormones and GTP affect the dynamic interplay between multimeric G proteins and receptors in a fashion analogous to the actions of ATP on the dynamic interactions between myosin and actin filaments. Signal transduction is mediated by activated monomers released from the multimers during the activation process.

Fecal bile acid excretion and composition in response to changes in dietary wheat bran, fat and calcium in the rat.

The effect and possible interactive influence of different dietary amounts of wheat bran, fat and calcium on the fecal excretion, concentration and composition of bile acids was studied in Fischer-344 rats. The fecal bile acids were analyzed using gas-liquid chromatography. Dietary wheat bran increased both total bile acid excretion and fecal weight without changes in fecal bile acid concentration. The proportion of fecal hyodeoxycholic acid decreased with increasing dietary fiber, whereas that of lithocholic and deoxycholic acids increased significantly with fiber intake. The percent content of fecal chenodeoxycholic acid did not change. Increasing dietary fat led to an increase in bile acid excretion without changes in either fecal weight or bile acid concentration. In contrast, the level of dietary calcium did not affect the total excretion of bile acids. However, since calcium increased the fecal weight, it consequently diluted bile acids and decreased their fecal concentration. Dietary fat and calcium had no influence on fecal bile acid composition. There were no interactive effects of wheat bran, fat and calcium on fecal bile acids. The finding in this study that dietary fiber, fat and calcium induce significant changes in fecal bile acids may be of relevance to the potential of bile acids to promote carcinogenesis.

Magnesium and calcium absorption in Fischer-344 rats influenced by changes in dietary fibre (wheat bran), fat and calcium.

Magnesium and calcium absorption were affected by changes in dietary wheat bran fibre and calcium, but not fat, in Fischer-344 rats when studied in a full factorial study which was a portion of a larger study of diet and colon carcinogenesis. For four weeks, nine-week-old rats were fed experimental purified diets to which had been added: wheat bran 0, 2.5 10, or 20%; fat 1, 5 or 10%; and calcium 0.18, 0.52, or 1.04% of diet weight. From day 26 to 29 all faeces were collected in metabolic cages, and food consumption noted. Dietary magnesium intake and net magnesium absorption increased in direct relation to the quantity of wheat bran in the diet. Calcium supplementation inhibited magnesium absorption on fibre-free diet, but had little effect on magnesium absorption when fibre was present. Fat had no measurable effect on magnesium absorption. A low dietary fibre content enhanced Ca absorption compared to that on a fibre-free diet. However, further increases in fibre content slightly inhibited calcium absorption. We conclude that the magnesium content of dietary wheat bran fibre is available for absorption to rats. Calcium supplementation inhibits magnesium absorption in a fibre-free diet, but presence of dietary fibre protects magnesium absorption from the calcium inhibition observed on a fibre-free diet. Absorption of calcium is increased by including some fibre in the diet. However, calcium absorption may be diminished slightly by increasing wheat bran content of the diet to a high level, probably through calcium binding and excretion with undigested fibre.

Serum gastrin increases with increasing dietary calcium but not with increasing dietary fat or fiber in Fischer-344 rats.

We studied the effects of dietary calcium, fat and fiber on serum gastrin in Fischer-344 rats in a full factorial experiment as part of a larger study of diet and colon cancer risk factors. Nine- to 10-wk-old male rats were fed standard or experimental diets for 4 wk. Wheat bran was the sole source of fiber. Wheat bran levels were 0, 2.5, 10 and 20%; fat levels were 1, 5 and 10%; calcium levels were 0.18, 0.52 and 1.04% of diet weight. On d 29 serum was collected and stored at -80 degrees C until analyzed. There was a significant (P less than 0.0001) dose-dependent increase in serum gastrin from 102 to 173 ng/L, with increasing calcium. No other significant changes in serum gastrin were noted with the dietary changes. A long-term change in the level of serum gastrin, caused by dietary modification, will influence the trophic effect that gastrin has on colonic mucosa as well as on colon carcinomas. We speculate that calcium supplementation, although slowing colonic proliferation, might have an undesirable effect on the growth of early undetected colonic tumors.

Influence of microenvironmental pH on adriamycin resistance.

Resistance to Adriamycin (ADR) is frequently dependent upon enhanced efflux associated with the expression of the MDR1-encoded P membrane glycoprotein. Since enhanced expression of the MDR1 gene in ADR-resistant cells may be the result of spontaneous genetic mutation or amplification, it is presumed to be relatively stable and unalterable. Yet, reducing ADR efflux could increase sensitivity, and has been attempted using calcium channel blockers and other drugs. However, since the tumor cell microenvironment varies with respect to pH because of differences in vascularization, oxygenation, and metabolite clearance, the possibility exists that these factors could influence drug transport and the critical biochemical pathways which determine cytotoxicity, even in resistant cells. Using flow cytometric analysis of ADR fluorescence, the influx and efflux of 10 microM ADR dissolved in MES buffer (pH 6.5) and 4-(2-hydroxyethylene)-1-piperazineethanesulfonic acid buffer (pH 7.5 and 8.5) was measured in sensitive P388 and resistant P388/R84 cells in vitro. Substantially enhanced uptake of ADR was detected at alkaline pH in both cell populations, while the proportion of ADR-positive cells and the level of ADR uptake was decreased at lower pH. Acidification reduced ADR efflux, whereas alkalinization increased efflux when the uptake pH was 6.5 or 7.5. At uptake pH 8.5, the pH of the external buffer had little effect, even in resistant cells. In resistant cells in an alkaline microenvironment, ADR transport and retention were superior to that observed in sensitive cells in an acidic microenvironment. No differences were observed in ADR transport when the transmembrane pH gradient was equilibrated. These observations are especially relevant to the effect of ADR on tumor cell subpopulations that are acidic, and in which drug diffusion is inefficient. Efforts to alkalinize tumor cells prior to ADR therapy might reduce ADR resistance, even of genetic origin.

Transport of beta-adrenergic antagonists in the absence of beta-adrenergic receptors in rat pituitary tumor cells.

We have demonstrated that the rat pituitary tumor cell line GH3 has a carrier-mediated active transport system for the beta-adrenergic antagonist dihydroalprenolol (DHA). Transport of DHA in GH3 was saturable, with an apparent Km of 1.4 microM, was temperature and pH dependent, and was inhibited by the ionophore monensin and the amine transport inhibitor reserpine. Propranolol competed for DHA transport, but not in a stereoselective fashion. The tricyclic antidepressant imipramine also competed for DHA transport, but catecholamines or serotonin did not. This amine transport system in GH3 cells appeared to be identical to the one we recently described in several other cell types; however, analysis in those cells was complicated by the fact that they contain beta-adrenergic receptors which bind beta-adrenergic ligands. In this report we show that GH3 cells do not possess detectable beta-adrenergic receptors, based on their inability to bind the partial agonist CGP-12177, their inability to bind nanomolar concentrations of DHA in a saturable, stereospecific manner, and their failure to produce cAMP in response to stimulation by beta-adrenergic agonists. Characterization of the amine transport system in GH3 cells clearly distinguishes it from receptor-mediated phenomena and should facilitate our efforts to fully understand its mechanism and significance.