Lessons learnt from the COVID-19 pandemic in selected countries to inform strengthening of public health systems: a qualitative study.

INTRODUCTION: The COVID-19 pandemic has prompted governments internationally to consider strengthening their public health systems. To support the work of Ireland's Public Health Reform Expert Advisory Group, the Health Information and Quality Authority, an independent governmental agency, was asked to describe the lessons learnt regarding the public health response to COVID-19 internationally and the applicability of this response for future pandemic preparedness. METHODS: Semi-structured interviews with key public health representatives from nine countries were conducted. Interviews were conducted in March and April 2022 remotely via Zoom and were recorded. Notes were taken by two researchers, and a thematic analysis undertaken. RESULTS: Lessons learnt from the COVID-19 pandemic related to three main themes: 1) setting policy; 2) delivering public health interventions; and 3) providing effective communication. Real-time surveillance, evidence synthesis, and cross-sectoral collaboration were reported as essential for policy setting; it was noted that having these functions established prior to the pandemic would lead to a more efficient implementation in a health emergency. Delivering public health interventions such as testing, contact tracing, and vaccination were key to limiting and or mitigating the spread of the SARS-CoV-2 virus. However, a number of challenges were highlighted such as staff capacity and burnout, delays in vaccination procurement, and reduced delivery of regular healthcare services. Clear, consistent, and regular communication of the scientific evidence was key to engaging citizens with mitigation strategies. However, these communication strategies had to compete with an infodemic of information being circulated, particularly through social media. CONCLUSIONS: Overall, functions relating to policy setting, public health interventions, and communication are key to pandemic response. Ideally, these should be established in the preparedness phase so that they can be rapidly scaled-up during a pandemic.

Raman spectroscopy of primary bovine aortic endothelial cells: a comparison of single cell and cell cluster analysis.

There are many techniques that allow in vitro interactions among cells and their environment to be monitored, including molecular, biochemical and immunochemical techniques. Traditional techniques for the analysis of cells often require fixation or lysis from substrates; however, use of such destructive methods is not feasible where the expanded cell cultures are required to be used for clinical implantation. Several studies have previously highlighted the potential of Raman spectroscopy to provide useful information on key biochemical markers within cells. As such, we highlight the capability of Raman spectroscopy with different laser spot sizes for use as a non-invasive, rapid, and specific method to perform in situ analysis of primary bovine aortic endothelial cells (BAECs). Raman spectra were collected from both individual live cells cultured on fused silica substrates and on clusters of live cells placed on fused silica substrates, measured at 532 and 785 nm. The results obtained show notable spectral differences in DNA/RNA region indicative of the relative cytoplasm and nucleus contributions. Raman spectra of cell clusters show slight variations in the intensity of the phenylalanine peak (1004 cm(-1)) indicating variations in protein contribution. These spectra also highlight contributions from other cellular components such as, proteins, lipids, nucleic acids and carbohydrates, respectively.

Effect of tau on the vinblastine-induced aggregation of tubulin.

Two microtubule-associated proteins, tau and the high molecular weight microtubule-associated protein 2 (MAP 2), were purified from rat brain microtubules. Addition of either protein to pure tubulin caused microtubule assembly. In the presence of tau and 10 microM vinblastine, tubulin aggregated into spiral structures. If tau was absent, or replaced by MAP 2, little aggregation occurred in the presence of vinblastine. Thus, vinblastine may be a useful probe in elucidating the individual roles of tau and MAP 2 in microtubule assembly.

Identification and characterization of osteoclast-like cells and their progenitors in cultures of feline marrow mononuclear cells.

The predominant cell responsible for bone resorption, the multinucleated osteoclast, has been difficult to study because of inaccessibility. When feline marrow-derived mononuclear cells are established in long-term culture, multinucleated cells form within 48 h, reaching maximum numbers at 16 d. We have observed that these cultured cells have many of the features of osteoclasts. Morphologically, they are multinucleated, contain large numbers of branched mitochondria, have a peripheral cytoplasm lacking organelles (a clear zone), and have extensive cell-surface processes. In addition to these ultrastructural features, the cells contain a tartrate-resistant acid phosphatase, the activity of which is increased by parathyroid hormone (PTH) and inhibited by calcitonin. PTH, prostaglandin E2, and 1,25(OH)2 vitamin D3 increased multinucleated cell formation, while calcitonin inhibited the stimulatory effects of PTH. Time-lapse cinemicrographic and autoradiographic studies indicated that the multinucleated cells formed by fusion of the mononuclear progenitors. The multinucleated cells were phagocytic and stained with nonspecific esterase, consistent with their being derived from immature monocytes. Further, cell populations enriched for multinucleated cells release 45Ca from devitalized bone. Density-gradient centrifugation on Percoll was used to enrich and characterize the mononuclear progenitors of these multinucleated cells. The progenitor cells were found predominantly in Percoll density layers of 1.065 to 1.08 g/ml and were enriched up to 30-fold as compared to unfractionated cells. The bone marrow mononuclear cells that formed the multinucleated cells were initially nonadherent to plastic, stained heavily with nonspecific esterase, and appeared to be immature monocytes histologically. These data indicate that the multinucleated osteoclast-like cells in our cultures are derived from nonadherent monocytic progenitor cells that are responsive to osteotropic hormones. The ability to grow and characterize these cells in vitro should facilitate studies to elucidate the role these cells play in normal and pathologic states of bone resorption.

Human platelet stimulation by acetyl glyceryl ether phosphorylcholine.

Acetyl glyceryl ether phosphorylcholine (AGEPC) induced dose-dependent platelet aggregation and release of [3H]serotonin and platelet factor 4 in citrated human platelet-rich plasma. ADP scavengers or indomethacin prevented irreversible platelet aggregation responses induced by 0.2 microM AGEPC but had no effect upon platelet secretion; prostacyclin inhibited AGEPC-induced aggregation and secretion. EDTA or EGTA inhibited AGEPC-induced aggregation but had no effect on platelet secretion.

Atypical multinucleated cells form in long-term marrow cultures from patients with Paget's disease.

Although Paget's disease is the most flagrant example of a primary osteoclast disorder, little is known of osteoclast biology in this disease. In this report we have studied the formation of cells with the osteoclast phenotype in long-term cultures of marrow mononuclear cells derived from patients with Paget's disease, and compared these with similar cells formed in long-term marrow cultures from normal individuals, and with osteoclasts present in pagetic bone. Osteoclasts formed in pagetic marrow cultures resembled osteoclasts present in pagetic bone, but were distinctly different from osteoclasts formed in normal marrow cultures. Osteoclast formation was 10-20-fold greater in pagetic marrow cultures than in normal cultures. The multinucleated cells formed in cultures of pagetic marrow were much larger in size, were hyperresponsive to 1,25(OH)2 vitamin D, had more nuclei per cell, had increased levels of tartrate-resistant acid phosphatase activity and had ultrastructural features which were not seen in multinucleated cells formed from normal marrow mononuclear cells. These pagetic marrow-derived multinucleated cells formed large resorption lacunae on calcified matrices and cross-reacted with monoclonal antibodies which preferentially bind to osteoclasts. The multinucleated cells formed from marrow obtained from uninvolved sites in Paget's patients also displayed these abnormal features.

Complement localization and mediation of ischemic injury in baboon myocardium.

We sought to determine whether the third component of complement (C3) is localized in ischemic baboon myocardium after coronary artery ligation. Furthermore, we assessed the effects of prior C3 depletion on myocardial necrosis. We studied seven control baboons (group I) and seven C3-depleted (group II) baboons that were killed 24 h after ligation of the anterior descending coronary artery. Multiple tissue samples were obtained from infarct, intermediate, and normal myocardial sites as defined by serial unipolar epicardial ECG mapping. In group I baboons, myocardial creatine kinase content from infarct sites was reduced as compared with normal sites (12.6+/-0.92 [SE] vs. 24.4+/-0.75 IU/mg protein, P < 0.001). The intermediate sites from group I contained more creatine kinase (19.0+/-1.25 IU/mg protein) than infarct sites (P < 0.001), but less (P < 0.025) than normal sites. In group II, intermediate sites showed no significant reduction in creatine kinase from normal sites and there was significantly less creatine kinase depletion in infarct sites when compared with group I animals (33.7+/-4.6 and 51.4+/-1.8% depletion, respectively, P < 0.001). In all seven group I baboons, uniform C3 localization was observed in infarct sites by direct immunofluorescence but appeared in mosaic patterns in intermediate sites. C3 was not demonstrated in any normal sites, nor in any site from group II baboons. Additional studies on baboons killed at earlier times after ligation indicated that C3 was localized focally on swollen myocytes in infarct sites as early as 4 h after coronary ligation. These results strongly implicate the active participation of the complement system of inflammatory proteins in the pathogenesis of myocardial tissue injury following coronary occlusion.

Osteoclast-like cells form in long-term human bone marrow but not in peripheral blood cultures.

Transplantation studies have suggested that peripheral blood mononuclear cells contain precursors for osteoclasts. Thus we tested the capacity of peripheral blood monocytes to form osteoclasts in long-term culture. We have reported previously that mononuclear cells from feline, baboon, and human marrow form osteoclast-like cells in long term cultures. Further, the formation of these cells is increased in response to bone resorption stimulatory agents such as PTH, interleukin 1, and transforming growth factor alpha. We now report that these cells show characteristic cytoplasmic contraction with calcitonin and form resorption lacunae when cultured on sperm whale dentine. Thus, these bone marrow-derived multinucleated cells fulfill the functional criteria for osteoclasts. Although cultured peripheral blood monocytes can be induced to form multinucleated cells with 1,25-dihydroxyvitamin D3, these cells did not show similar responses to the osteotropic factors as multinucleated cells formed in the bone marrow cultures multinucleated cells. These results indicate that osteoclasts or cells closely related to osteoclasts form in long-term human bone marrow cultures. In contrast, few mononuclear cells in the peripheral blood appear capable of forming osteoclasts under the culture conditions used in these experiments.

Peri-implant inflammation defined by the implant-abutment interface.

An implant-abutment interface at the alveolar bone crest is associated with sustained peri-implant inflammation; however, whether magnitude of inflammation is proportionally dependent upon interface position remains unknown. This study compared the distribution and density of inflammatory cells surrounding implants with a supracrestal, crestal, or subcrestal implant-abutment interface. All implants developed a similar pattern of peri-implant inflammation: neutrophilic polymorphonuclear leukocytes (neutrophils) maximally accumulated at or immediately coronal to the interface. However, peri-implant neutrophil accrual increased progressively as the implant-abutment interface depth increased, i.e., subcrestal interfaces promoted a significantly greater maximum density of neutrophils than did supracrestal interfaces (10,512 +/- 691 vs. 2398 +/- 1077 neutrophils/mm(2)). Moreover, inflammatory cell accumulation below the original bone crest was significantly correlated with bone loss. Thus, the implant-abutment interface dictates the intensity and location of peri-implant inflammatory cell accumulation, a potential contributing component in the extent of implant-associated alveolar bone loss.

Human chorionic gonadotropin in human neoplastic cells.

Peroxidase-labeled antibody against the beta chain of human chorionic gonadotropin was used to demonstrate that 25 human malignant tumors contained this antigen. The antigen was localized both in the cytoplasm and on the surface of the malignant cells. Human chorionic gonadotropin may be responsible for both selective maternal immuno-suppression by fetal tissue and host immunosuppression by tumors.

Localization of the beta chain of human chorionic gonadotropin on human tumor cells and placental cells.

With the use of peroxidase-labeled antibody to the beta chain of human chorionic gonadotropin, sections of ten human malignant tumors were found to react with this antibody. It is postulated that both selective host immunosuppression by tumors and selective maternal immunosuppression by fetal tissues may be mediated by human chorionic gonadotropin.

Subannular tube insertion: anatomical considerations.

OBJECTIVES: To assess the distance between the bony groove created during subannular tubes placement and the chorda tympani, and examine the depth of the hypotympanum and retrotympanum. METHOD: Grooves drilled in cadaver temporal bones at two levels were imaged to measure: the distance between the chorda tympani nerve and the tympanic sulcus, and the depth of the hypotympanum and the retrotympanum relative to the annulus. RESULTS: The chorda tympani was between 0 and 5 mm from the groove cut across the annulus. The hypotympanum average depth was 2 mm (0.44-6.40 mm) and the retrotympanum average depth was 1 mm (0-2.53 mm). CONCLUSION: Grooves drilled across the tympanic sulcus should be placed at a point 20 per cent of the height of the tympanic membrane or lower; this will ensure least risk of injury to the chorda tympani nerve. The depth of the hypotympanum and retrotympanum dictates that the posteroinferior part of a subannular tube flange should be approximately 2 × 1 mm.

Molecular heterogeneity of PAF in normal human mixed saliva: quantitative mass spectral analysis after direct derivatization of PAF with pentafluorobenzoic anhydride.

Platelet-activating factor (PAF), a family of phospholipid autacoids with potent pro-inflammatory activities, is present in saliva. The current study has quantitated various species of PAF isolated from normal human mixed saliva. Choline-containing, sn-2 acetylated phospholipids with sn-1 ether- or ester-linked fatty alcohol/acid moieties (alkyl-PAF or acyl-PAF, respectively) were evaluated after direct derivatization with pentafluorobenzoic (PFB) anhydride. Individual species of PFB-derivatized PAF were separated by gas chromatography prior to mass spectral analysis; quantitative estimates of six different species of PAF in saliva were made by comparison to corresponding authentic, synthetic PAF standards. In each saliva sample, all six species of PAF were readily detected by this facile procedure. The predominant PAF was 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine or 16:0-alkyl-PAF (0.75 +/- 0.09 pmol/ml saliva; mean +/- S.E.; n = 5) which represented only 30.4 +/- 1.5% of the total PAF. Substantial amounts of 18:1- and 18:0-alkyl-PAF and 16:0-acyl-PAF were also identified (0.52 +/- 0.07, 0.35 +/- 0.06, and 0.35 +/- 0.02 pmol/ml saliva, respectively). In summary, mass spectrometric analysis of PAF after direct derivatization with PFB anhydride has revealed that at least six different species of PAF are present in normal human mixed saliva. This structural diversity may represent an important aspect of homeostasis in the healthy oral cavity.

Agonist-dependent failure of neutrophil function in diabetes correlates with extent of hyperglycemia.

Inexplicable controversies with regard to possible functional defects of neutrophilic polymorphonuclear leukocytes (PMNs) in diabetes persist. The purpose of the present study was to elucidate the relative effectiveness of several PMN agonists in stimulating lysosomal-enzyme secretion and leukotriene (LT) B(4) production by PMNs isolated from diabetic subjects. Formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) induced significantly less lysosomal-enzyme secretion and LTB(4) production in diabetic-subject PMNs than in normal-subject PMNs. It is surprising that PMNs from these same diabetic subjects responded normally after stimulation with A23187, serum-opsonized zymosan, or phorbol myristate acetate. The in vitro responsiveness of PMNs stimulated with fMLP or PAF was inversely correlated with indices of in vivo glycemic control (fasting plasma glucose and glycated-hemoglobin levels). In combination, these results indicate that hyperglycemia is associated with sustained decreases in PMN function but only in response to agonists that initiate stimulus-response coupling via G-protein-coupled receptors. This agonist-selective reduction in PMN responsiveness may contribute to the compromised host defense associated with sustained hyperglycemia in diabetes.

Formation of multinucleated cells that respond to osteotropic hormones in long term human bone marrow cultures.

Studies of osteoclasts and their precursors in normal and pathological states have been severely hampered by the lack of an in vitro system for forming osteoclasts. We developed a human marrow culture system in which multinucleated cells with several characteristics of osteoclasts form. Multinucleated cells began to form during the first week of culture, with maximum numbers formed after 3 weeks. PTH (25-50 ng/ml) and 1,25-dihydroxyvitamin D3 (10(-10)-10(-8) M) increased formation of these cells, and these effects were inhibited by calcitonin. These multinucleated cells contained nonspecific esterase and tartrate-resistant acid phosphatase, a marker enzyme of osteoclasts, and had several ultrastructural features of osteoclasts. We used this marrow cell culture technique to study a patient with hyperparathyroidism and markedly increased osteoclasts on bone marrow biopsy. The marrow from this patient formed increased numbers of multinucleated cells in vitro. After parathyroidectomy both multinucleated cell formation in vitro and osteoclast numbers on bone biopsy decreased significantly. This long term marrow culture system represents the first demonstration of human osteoclast-like cell formation in vitro. This system should permit studies to evaluate factors controlling formation of cells with certain osteoclast characteristics in vitro and their precursors as well as to evaluate abnormalities in osteoclast formation in patients with metabolic bone disease.

Isolation and characterization of mouse C1q.

C1q was isolated from mouse serum and ascites fluid by absorption onto human IgG-coated latex beads followed by separation on 3-10% exponential gradient sodium dodecyl sulfate (SDS) polyacrylamide gels. Mouse C1q was also purified by low ionic strength precipitation of mouse serum. The purified C1q was heat-labile (56 degrees C, 30 min) both structurally and functionally, contained 4.3% hydroxyproline, 1.38% hydroxylysine, and 18.5% glycine, had an apparent molecular weight of 380,000 daltons, and reconstituted the hemolytic complement activity of C1q-depleted mouse serum. The negatively stained ultrastructural appearance of this purified material consisted of 6 globular units connected by strands. These data demonstrate that mouse C1q structurally and functionally is similar to human and rabbit C1q. A portion of polyacrylamide gel containing mouse C1q was injected into rabbits resulting in the production of monospecific antisera against mouse C1q. Thus, this procedure is a new, rapid and simple method to obtain monospecific antisera against mouse C1q.

Salivary PAF levels correlate with the severity of periodontal inflammation.

Platelet-activating factor (PAF), a potent phospholipid mediator of inflammation, has been previously identified in inflamed gingival tissues and gingival crevicular fluid. However, the role of PAF in oral pathobiology remains unknown. The purpose of the present study was to evaluate the relationship between salivary PAF levels and the severity of periodontal inflammation. PAF activity in lipid extracts of whole (mixed) saliva collected from 69 untreated subjects immediately prior to routine oral evaluation was determined by platelet bioassay. Significant positive correlations were observed between the level of PAF in saliva and measures of periodontal inflammation, i.e., the percentage of periodontal probing depths greater than 4 mm, the number of periodontal bleeding sites, and the number of histologically identified polymorphonuclear neutrophilic leukocytes (PMN) in saliva. Moreover, when subjects were subdivided into groups on the basis of periodontal probing depths, a significant correlation was observed between salivary PAF levels and the extent of periodontal disease, i.e., PAF levels in saliva progressively increased from the healthiest group to the most severely affected group. Thus, salivary PAF levels correlate with the severity of periodontal inflammation. These results support the hypothesis that this pro-inflammatory phospholipid autacoid may participate in the pathogenesis of periodontal tissue injury and disease.

Persistent acute inflammation at the implant-abutment interface.

The inflammatory response adjacent to implants has not been well-investigated and may influence peri-implant tissue levels. The purpose of this study was to assess, histomorphometrically, (1) the timing of abutment connection and (2) the influence of a microgap. Three implant designs were placed in the mandibles of dogs. Two-piece implants were placed at the alveolar crest and abutments connected either at initial surgery (non-submerged) or three months later (submerged). The third implant was one-piece. Adjacent interstitial tissues were analyzed. Both two-piece implants resulted in a peak of inflammatory cells approximately 0.50 mm coronal to the microgap and consisted primarily of neutrophilic polymorphonuclear leukocytes. For one-piece implants, no such peak was observed. Also, significantly greater bone loss was observed for both two-piece implants compared with one-piece implants. In summary, the absence of an implant-abutment interface (microgap) at the bone crest was associated with reduced peri-implant inflammatory cell accumulation and minimal bone loss.

Platelet activating factor in pulmonary pathobiology.

Platelet activating factor (PAF) is a potent phospholipid mediator of inflammation that has been gaining increasing attention because of its pathophysiologic effects upon the lung. In particular, PAF stimulates pulmonary hypertension, ventilatory alterations, bronchoconstriction, airway hyperreactivity, and pulmonary inflammatory cell accumulation and edema in a variety of experimental animals and in humans. These observations promote the speculation that this unique phospholipid likely is involved in similar tissue responses during the course of human lung disease. The use of specific PAF antagonists should expand our understanding of these processes and may be useful in treating or preventing PAF-mediated pulmonary disorders in the future.

The effect of initial periodontal therapy on salivary platelet-activating factor levels in chronic adult periodontitis.

Platelet-activating factor (PAF), a potent phospholipid inflammatory mediator, is increased in the mixed saliva of subjects with periodontal disease and correlates with the extent of oral inflammation. The present study was designed to provide a longitudinal evaluation of the effect of initial periodontal therapy (home care instruction, prophylaxis, and scaling/root planing) on salivary PAF levels in chronic adult periodontitis patients (n = 15). Mixed saliva was collected prior to, during, and after initial therapy and was utilized to assess PAF levels after lipid extraction and fractionation as well as to histologically assess the number of polymorphonuclear leukocytes (PMN). PAF activity was determined in bioassay relative to authentic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine; 16:0-alkyl-PAF). Initial salivary PAF levels (12.1 +/- 2.8 pmole equivalents of 16:0-alkyl-PAF/ml saliva; mean +/- SE) decreased following supragingival plaque control (9.6 +/- 2.4) and were further reduced following scaling and root planing (5.7 +/- 1.4). In parallel, salivary PMN levels were significantly reduced and clinical estimates of periodontal disease were significantly improved; i.e., there was a decrease in the percentage of sites with both bleeding on probing (from 46.1 +/- 4.6% of sites at pretreatment to 25.9 +/- 2.6% after scaling and root planing) and probing depths > or = 4 mm (from 16.7 +/- 1.9% of sites to 10.3 +/- 1.2%). Thus, initial periodontal therapy reduced salivary PAF levels in concert with improvements in clinical estimates of marginal and submarginal periodontal inflammation suggesting that PAF may participate in inflammatory events during periodontal tissue injury and disease.