SARS-CoV-2 cellular and humoral responses in vaccine-naive individuals during the first two waves of COVID-19 infections in the southern region of The Netherlands: a cross-sectional population-based study.

With the emergence of highly transmissible variants of concern, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) still poses a global threat of coronavirus disease 2019 (COVID-19) resurgence. Cellular responses to novel variants are more robustly maintained than humoral responses, and therefore, cellular responses are of interest in assessing immune protection against severe disease in the population. We aimed to assess cellular responses to SARS-CoV-2 at the population level. IFNγ (interferon γ) responses to wild-type SARS-CoV-2 were analyzed using an ELISpot assay in vaccine-naive individuals with different humoral responses: Ig (IgM and/or IgG) seronegative (n = 90) and seropositive (n = 181) with low (<300 U/mL) or high (≥300 U/mL) humoral responses to the spike receptor binding domain (anti-S-RBD). Among the seropositive participants, 71.3% (129/181) were IFNγ ELISpot positive, compared to 15.6% (14/90) among the seronegative participants. Common COVID-19 symptoms such as fever and ageusia were associated with IFNγ ELISpot positivity in seropositive participants, whereas no participant characteristics were associated with IFNγ ELISpot positivity in seronegative participants. Fever and/or dyspnea and anti-S-RBD levels were associated with higher IFNγ responses. Symptoms of more severe disease and higher anti-S-RBD responses were associated with higher IFNγ responses. A significant proportion (15.6%) of seronegative participants had a positive IFNγ ELISpot. Assessment of cellular responses may improve estimates of the immune response to SARS-CoV-2 in the general population. IMPORTANCE: Data on adaptive cellular immunity are of interest to define immune protection against severe acute respiratory syndrome coronavirus 2 in a population, which is important for decision-making on booster-vaccination strategies. This study provides data on associations between participant characteristics and cellular immune responses in vaccine-naive individuals with different humoral responses.

Barriers to participation in clinical trials: a physician survey.

Background: Clinical trials are vital for evidence-based cancer care. Oncologist engagement in clinical trials has an effect on patient recruitment, which in turn can affect trial success. Identifying barriers to clinical trial participation might enable interventions that could help to increase physician participation. Methods: To assess factors affecting physician engagement in oncology trials, a national survey was conducted using the online SurveyMonkey tool (SurveyMonkey, San Mateo, CA, U.S.A.; http://www.surveymonkey.com). Physicians associated with the Canadian Cancer Clinical Trials Network and the Canadian Cancer Trials Group were asked about their specialty, years of experience, barriers to participation, and motivating interventions, which included an open-ended question inviting survey takers to suggest interventions. Results: The survey collected 207 anonymous responses. Respondents were predominantly medical oncologists (46.4%), followed by radiation oncologists (24.6%). Almost 70% of the respondents had more than 10 years of experience. Significant time constraints included extra paperwork (77%), patient education (54%), and extended follow-up or clinic visits (53%). Timing of events within trials was also a barrier to participation (55%). Most respondents favoured clinical work credits (72%), academic credits (67%), a clinical trial alert system (75%), a regular meeting to review trial protocols (65%), and a screening log to aid in patient accrual (67%) as motivational strategies. Suggested interventions included increased support staff, streamlined regulatory burden, and provision of greater funding for trials and easier access to ancillary services. Conclusions: The present study confirms that Canadian oncologists are willing to participate in clinical research, but face multiple barriers to trial participation. Those barriers could be mitigated by the implementation of several interventions identified in the study.

Dietary supplementation with a specific combination of high protein, leucine, and fish oil improves muscle function and daily activity in tumour-bearing cachectic mice.

Cancer cachexia is characterised by metabolic alterations leading to loss of adipose tissue and lean body mass and directly compromises physical performance and the quality of life of cancer patients. In a murine cancer cachectic model, the effects of dietary supplementation with a specific combination of high protein, leucine and fish oil on weight loss, muscle function and physical activity were investigated. Male CD2F1 mice, 6-7 weeks old, were divided into body weight-matched groups: (1) control, (2) tumour-bearing, and (3) tumour-bearing receiving experimental diets. Tumours were induced by s.c. inoculation with murine colon adenocarcinoma (C26) cells. Food intake, body mass, tumour size and 24 h-activity were monitored. Then, 20 days after tumour/vehicle inoculation, the animals were killed and muscle function was tested ex vivo. Tumour-bearing mice showed reduced carcass, muscle and fat mass compared with controls. EDL muscle performance and total daily activity were impaired in the tumour-bearing mice. Addition of single nutrients resulted in no or modest effects. However, supplementation of the diet with the all-in combination of high protein, leucine and fish oil significantly reduced loss of carcass, muscle and fat mass (loss in mass 45, 52 and 65% of TB-con, respectively (P<0.02)) and improved muscle performance (loss of max force reduced to 55-64% of TB-con (P<0.05)). Moreover, total daily activity normalised after intervention with the specific nutritional combination (50% of the reduction in activity of TB-con (P<0.05)). In conclusion, a nutritional combination of high protein, leucine and fish oil reduced cachectic symptoms and improved functional performance in cancer cachectic mice. Comparison of the nutritional combination with its individual modules revealed additive effects of the single components provided.

Inhibition of the antianalgesic action of dynorphin A in mice by cholera toxin.

Dynorphin A-(1-17) (Dyn A) administered intrathecally (IT) or released spinally in the mouse produces an antianalgesic action. The present experiments indicate that IT administration of cholera toxin inhibited the antianalgesic action of Dyn A. When clonidine was administered intracerebroventricularly (ICV) to release spinal Dyn A, IT cholera toxin inhibited the antianalgesic action of Dyn A so that the analgesic component of action of clonidine became evident. Dyn A given IT inhibited the analgesic action of morphine given ICV. Cholera toxin given IT eliminated the antagonistic action of Dyn A. These results, in addition to others, indicate that IT cholera toxin antagonized the action of Dyn A. When the antianalgesic action of Dyn A was attenuated by pretreatment with dynorphin antiserum or by pretreatment that produced desensitization to Dyn A, cholera toxin had no effect. These results suggested that the antianalgesic action of Dyn A is mediated by activation of opioid receptors that are positively coupled to adenylate cyclase through a Gs regulatory protein.

Involvement of dynorphin A and not substance P in the spinal antianalgesic action of capsaicin against morphine-induced antinociception in mice.

In previous publications we proposed that dynorphin A (1-17) (Dyn) functions as an antianalgesic agent in the spinal cord of mice. Whether endogenously released or administered directly to the spinal cord, this antianalgesic action attenuates the antinociceptive effect of morphine (Mor) in the mouse tail-flick test. Because this action of Dyn in the spinal cord appeared to be congruous with the function of substance P (SP), experiments were designed to compare the actions of the two on Mor-induced antinociception. Inhibition of the tail-flick response induced by i.c.v. administration of Mor was attenuated by intrathecal (i.t.) administration of SP or Dyn. This antianalgesic effect of Dyn (5 fmol) but not SP (74 pmol) was antagonized by naloxone and nor-binaltorphimine administered i.t. Capsaicin (Cap) i.t. at a 0.1-microgram dose, like SP and Dyn, antagonized the antinociceptive effect of Mor given i.c.v. Excellent evidence exists to indicate that, in rats, Cap (30-70 micrograms i.t.) releases SP in the spinal cord and that Mor inhibits this release. Present experiments indicated, however, that i.t. administration of low doses of Cap (0.05-0.5 microgram) in mice preferentially released Dyn and not SP as based on the following results. 1) The antianalgesic action of Cap i.t. against Mor i.c.v. was antagonized by naloxone and nor-binaltorphimine i.t. as was Dyn i.t. (but not SP i.t.). 2) A SP antagonist, (D-Pro2, D-Phe7, D-Trp9)-SP, did not reverse the effect of Cap or Dyn given i.t., even though it antagonized the effect of SP.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential contribution of descending serotonergic and noradrenergic systems to central Tyr-D-Ala2-Gly-NMePhe4-Gly-ol5 (DAMGO) and morphine-induced antinociception in mice.

Differences in antinociceptive (inhibition of tail-flick response) action of morphine and Tyr-D-Ala2-Gly-NMePhe4-ol5 (DAMGO) were demonstrated by intracerebroventricular (i.c.v.) administration of these agonists along with intrathecal (i.t.) administration of a variety of antagonists: yohimbine, methysergide, naloxone and nor-binaltorphimine. Intracerebroventricular morphine analgesia was antagonized by either i.t. yohimbine or methysergide, whereas i.c.v. DAMGO analgesia was only antagonized by i.t. methysergide. Thus, for i.c.v. morphine-induced analgesia, descending spinal noradrenergic and serotonergic systems were involved, whereas for DAMGO analgesia, only the serotonergic system was involved. The dose-response curve for i.c.v. morphine reached a plateau at high doses, whereas i.c.v. DAMGO analgesia peaked at 10 ng and then decreased thereafter, producing a bell-shaped dose-response curve. This decrement in analgesic response could be reversed by low doses of i.t. methysergide and i.t. pindolol. It was concluded that activation of serotonin-1 (5-HT1) receptors plays a role in the decrease in analgesia from high doses of DAMGO. Combinations of i.t. morphine with i.t. 5-HT or i.t. clonidine produced additive or greater analgesic responses. Combinations of i.t. DAMGO with i.t. 5-HT or i.t. clonidine produced less than additive interactions. Part of the latter responses appeared to be due to activation of 5-HT1 receptors; blockade of these receptors by pindolol enhanced i.t. DAMGO-induced analgesia. Morphine and DAMGO differ further because i.c.v. morphine activated a descending antianalgesic pathway mediated by spinal dynorphin A(1-17), whereas i.c.v. DAMGO at a high dose did not. Thus, morphine and DAMGO differ in their modes of antinociceptive action as measured by the tail-flick response.

Spinal dynorphin A (1-17): possible mediator of antianalgesic action.

Earlier studies from this laboratory indicated that intracerebroventricular administration of physostigmine and clonidine activated both a spinal descending analgesic and antianalgesic system. It was proposed that the latter was mediated spinally by dynorphin A (1-17), because small intrathecal doses (fmol) of dynorphin A (1-17) antagonized analgesia, while intrathecal administration of naloxone and nor-binaltorphimine (at doses which had no effect on spinal mu and kappa receptors) enhanced analgesia by attenuating the antianalgesic component. In the present studies in mice, using the tail-flick response, intrathecal administration of dynorphin antibody (antiserum to dynorphin) enhanced the analgesic effect of (10 min) physostigmine and clonidine given intraventricularly. Peak effect for the antiserum was at 1 hr. Inhibition of the tail-flick response, induced by DAMGO (Tyr-D-Ala2-Gly-NMePhe4-Gly-ol5, a mu agonist), U50, 488 H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzeneacetamide methanesulfonate hydrate, a kappa agonist) and morphine was also enhanced by intrathecal administration of dynorphin antiserum. Thus, a variety of analgesic agonists appear to activate a dynorphin-mediated antianalgesic system. Such a system appears not to be activated by intraventricular administration of beta-endorphin and DPDPE (D-Pen2-D-Pen5-enkephalin, a delta agonist) because neither beta-endorphin- nor DPDPE-induced analgesia was enhanced by intrathecal administration of antiserum. The results of the experiments with the antibody provide further evidence to support the role of dynorphin A (1-17), as a putative endogenous opioid, which mediates an antianalgesic descending system in the spinal cord.

Clonidine, administered intracerebroventricularly in mice, produces an anti-analgesic effect which may be mediated spinally by dynorphin A (1-17).

Clonidine, administered intracerebroventricularly, was shown to have two actions in the tail-flick test in mice: an overt anti-analgesic and a latent analgesic effect. The anti-analgesic effect was demonstrated by antagonism of the antinociceptive response to morphine, administered intrathecally. This anti-analgesic effect was attenuated by naloxone and nor-binaltorphimine, given intrathecally. Given intracerebroventricularly by itself, clonidine had no antinociceptive effect; however, the administration of naloxone and nor-binaltorphimine intrathecally uncovered the latent antinociceptive action of clonidine given intracerebroventricularly. This sensitivity to the opioid antagonists, given intrathecally, indicated that an endogenous anti-analgesic opioid might mediate the actions of clonidine at the spinal level. The putative opioid was postulated to be dynorphin A (1-17). Analgesia induced by intrathecally administered morphine was attenuated by the intrathecal administration of dynorphin A (1-17) at doses of less than 10 pg (5 fmol). This action of dynorphin was blocked by naloxone (5 fg, 0.014 fmol) and nor-binaltorphimine (10 ng, 12.3 pmol) at doses which did not block mu and kappa receptors in the spinal cord. The authors propose that clonidine, given intracerebroventricularly, activates an anti-analgesic system which descends spinally and is mediated by dynorphin A (1-17) in the spinal cord. This anti-analgesic effect of dynorphin A (1-17) appears to be a new function for dynorphin A (1-17).