Comparative analysis of risk factors for COVID-19 mortality before, during and after the vaccination programme in Mexico.

OBJECTIVES: The purpose of this study was to compare case fatality rates (CFRs) and odds for mortality by risk factors of patients with COVID-19 in Mexico, before, during and after the implementation of the national COVID-19 vaccination programme. STUDY DESIGN: A large database including COVID-19 monitoring cases was used to perform an observational retrospective study. METHODS: The Chi-squared test and multivariate logistic regression analyses were applied to data from COVID-19-positive patients in Mexico. Data were analysed over 3 years, 2020, 2021 and 2022, corresponding with pre-, during and post-vaccination periods. The unadjusted odds ratios and 95% confidence interval were used to estimate the risk factors for COVID-19 mortality in each of the years. RESULTS: Statistically significant differences in CFR and odds ratio were found in the studied years, favouring postvaccination period. Significant changes in CFR by age, sex and main comorbidities indicated changes in the epidemic dynamics after the implementation of the COVID-19 vaccination campaign. The likelihood of death increased for hospitalised cases and for patients who were middle-aged or older in 2021 and 2022, whereas the odds of death associated with sex and comorbidities remained similar or reduced over the 3 years. CONCLUSIONS: Implementation of the COVID-19 vaccination programme during 2021 showed positive consequences on CFR. The increased odds of dying in hospitalised patients are likely to be due to the unvaccinated proportion of patients.

Microvascular engineering: Dynamic changes in microgel-entrapped vascular cells correlates with higher vasculogenic/angiogenic potential.

Successful strategies to promote neovascularization of ischemic tissues are still scarce, being a central priority in regenerative medicine. Microparticles harboring primitive vascular beds are appealing cell delivery candidates for minimally-invasive therapeutic vascularization. However, dynamic cellular alterations associated with in vitro vascular morphogenesis are still elusive. Here, bioengineered microgels guided the assembly of entrapped outgrowth endothelial cells (OEC) and mesenchymal stem cells (MSC) into cohesive vascularized microtissues. During in vitro maturation, OEC formed capillary-like networks enveloped in newly-formed extracellular matrix. Gene expression profiling showed that OEC acquired a mesenchymal-like phenotype, suggesting the occurrence of partial endothelial-to-mesenchymal transition (EndMT), while MSC remained transcriptionally stable. The secretome of entrapped cells became more pro-angiogenic, with no significant alterations of the inflammatory profile. Importantly, matured microgels showed improved cell survival/retention after transplantation in mice, with preservation of capillary-like networks and de novo formation of human vascular structures. These findings support that in vitro priming and morphogenesis of vessel-forming cells improves their vasculogenic/angiogenic potential, which is of therapeutic relevance, shedding some light on the associated mechanisms.

Guiding morphogenesis in cell-instructive microgels for therapeutic angiogenesis.

Efficient cell delivery strategies are urgently needed to improve the outcome of cell-based pro-angiogenic therapies. This study describes the design of an injectable cell delivery platform, based on biomaterial-guided morphogenesis principles. Soft high-mannuronic acid alginate microgels, oxidized and functionalized with integrin-binding peptides, provided adequate biochemical/biomechanical cues for the co-assembly of mesenchymal stem cells and outgrowth endothelial cells (OEC) into pre-vascularized microtissues. In vitro priming conditions regulated OEC tubulogenesis, which only occurred under normoxia (+O2) in the presence of angiogenic factors (+GF) and, importantly, did not revert in an ischemic-like environment. Primed (+O2+GF) microgel-entrapped cells secreted a large variety of angiogenesis-related proteins and produced endogenous extracellular-matrix, rich in fibronectin and collagen type I, fostering cell-cell/cell-matrix interactions and establishing a stable angiogenic niche. Extending the pre-culture time resulted in higher cell outward migration and in vivo angiogenic potential. Microgels partially disintegrated upon implantation in chick embryos, promoting interaction between pre-vascularized microtissues and the host. Preserved human vascular structures were still detected in vivo, and human cells showed the ability to migrate and integrate with the chick vasculature. Our results suggest that an integrated approach combining pro-angiogenic cells, cell-instructive microgels and adequate in vitro priming may provide the basis for successful therapeutic angiogenesis.

Bioactive polymeric-ceramic hybrid 3D scaffold for application in bone tissue regeneration.

The regeneration of large bone defects remains a challenging scenario from a therapeutic point of view. In fact, the currently available bone substitutes are often limited by poor tissue integration and severe host inflammatory responses, which eventually lead to surgical removal. In an attempt to address these issues, herein we evaluated the importance of alginate incorporation in the production of improved and tunable ß-tricalcium phosphate (ß-TCP) and hydroxyapatite (HA) three-dimensional (3D) porous scaffolds to be used as temporary templates for bone regeneration. Different bioceramic combinations were tested in order to investigate optimal scaffold architectures. Additionally, 3D ß-TCP/HA vacuum-coated with alginate, presented improved compressive strength, fracture toughness and Young's modulus, to values similar to those of native bone. The hybrid 3D polymeric-bioceramic scaffolds also supported osteoblast adhesion, maturation and proliferation, as demonstrated by fluorescence microscopy. To the best of our knowledge this is the first time that a 3D scaffold produced with this combination of biomaterials is described. Altogether, our results emphasize that this hybrid scaffold presents promising characteristics for its future application in bone regeneration.

Fibrinogen promotes resorption of chitosan by human osteoclasts.

The osteoconductive and osteoinductive properties of materials intended for bone regeneration have been extensively tested, but the resorbability of these materials is often overlooked. Osteoclasts are responsible for bone resorption and play a crucial role in bone remodeling, which is essential for complete regeneration of bone tissue following injury. In this study we compare, for the first time, the ability of unmodified and fibrinogen (Fg)-modified chitosan (Ch) substrates to support the formation of multinucleated osteoclasts, and the potential of these cells to resorb the two substrates in vitro. Osteoclasts were differentiated from primary human peripheral blood monocytes directly on the substrates being investigated. Our results showed similar cell adhesion to unmodified and Fg-modified Ch substrates. Although the number of multinucleated osteoclasts on both Ch substrates increased throughout the culture period, by 21 days of culture significantly more highly multinucleated osteoclasts (>10 nuclei per cell) were observed on Fg-modified Ch, when compared to Ch alone. In addition, cells were tartrate-resistant acid phosphatase positive and secreted significantly more enzyme on Ch-based substrates than in control conditions. Unmodified and Fg-modified Ch resorption was investigated by fluorescence microscopy and confirmed by electron microscopy. Quantification of results obtained by fluorescence microscopy shows that Fg modification led to significantly higher substrate resorption by 17 days of culture. Our results show that osteoclasts, beyond resorbing mineralized substrates, successfully resorb a polymeric substrate (Ch), with Fg accelerating this process. Thus, in bone tissue regeneration strategies employing polymeric biomaterials, resorption may depend not only on macrophages, but also on osteoclasts.

TCF bleaching of wheat straw pulp using ozone and xylanase. Part A: paper quality assessment.

The XOAZRP TCF sequence was applied to bleach wheat straw pulp. Following each bleaching stage, the properties of the pulp (viz. kappa number, standard viscosity, borohydride viscosity and brightness) and of the resulting effluents were determined. The performance of the reagents was analyzed through the studies of xylanase treatment and crystallinity and scanning electron microscopy of the pulps. Finally, the pulp was refined at 1000 revolutions in a PFI mill and the mechanical properties of the resulting paper were determined and compared with those of paper from a eucalyptus pulp. Despite its shortcomings, wheat straw pulp can be effectively bleached with the proposed TCF sequence.

TCF bleaching of wheat straw pulp using ozone and xylanase. Part B: kinetic studies.

The reaction kinetics of ozone bleaching of wheat straw pulp has been studied for the first time. The results were compared with eucalyptus pulp in order to know that both raw materials have a similar behaviour. Ozone treatments were carried out in a special reactor at low consistency (0.5% o.d.p.). The main variables were consumption of ozone by the pulp and application of a xylanase treatment (X) prior to the oxygen stage (O). The responses measured were kappa number, viscosity and brightness, to give the kinetic expressions for delignification, cellulose degradation and elimination of chromophore groups, along with calculation of selectivity. Cellulose degradation and elimination of lignin and chromophore groups show first-order kinetics in all cases. The kinetics of the enzyme pre-treatment effect shows similar behaviour in both raw materials, although the constants of delignification and elimination of chromophore are higher in straw pulp.

Diabetes mellitus in a subgroup of older Mexicans: prevalence, association with cardiovascular risk factors, functional and cognitive impairment, and mortality.

OBJECTIVES: To examine the prevalence and effects of diabetes mellitus in a subgroup of older Mexicans to allow comparisons to older persons of Mexican origin living in the United States. DESIGN: Longitudinal study. SETTING: High-rise retirement housing in Mexico City. PARTICIPANTS: Seven hundred eighty-five public servants and their family members aged 65 and older. MEASUREMENTS: Geriatric survey of function; mental status and depression; a physical examination; and blood samples for glucose and cholesterol. RESULTS: The prevalence of diabetes mellitus in this population was 15.1%, substantially lower than the prevalence reported in people of Mexican origin living in the United States. Nondiabetics were more obese than diabetics. Diabetes mellitus was more common in men than women. The mortality rate was greater in diabetics than nondiabetics (relative risk=1.73, P <.05). Diabetics had more coronary artery disease and were more likely to die from myocardial infarction and neoplasms than nondiabetics. Diabetics were more likely to be functionally impaired (P <.0001) but no more likely to fall or to have fractures. Diabetics did not differ from nondiabetics in cognitive impairment or level of dysphoria. CONCLUSION: These studies highlight some important similarities and differences in comparing a middle class subgroup of older diabetics in Mexico City with diabetics of Mexican origin living in the United States.

Molecular cloning and characterization of a multidomain endoglucanase from Paenibacillus sp BP-23: evaluation of its performance in pulp refining.

The gene celB encoding an endoglucanase from Paenibacillus sp. BP-23 was cloned and expressed in Escherichia coli. The nucleotide sequence of a 4161 bp DNA fragment containing the celB gene was determined, revealing an open reading frame of 2991 nucleotides that encodes a protein of 106,927 Da. Comparison of the deduced amino acid sequence of endoglucanase B with known beta-glycanase sequences showed that the encoded enzyme is a modular protein and exhibits high homology to enzymes belonging to family 9 cellulases. The celB gene product synthesized in E. coli showed high activity on carboxymethyl cellulose and lichenan while low activity was found on Avicel. Activity was enhanced in the presence of 10 mM Ca2+ and showed its maximum at 53 degrees C and pH 5.5. The effect of the cloned enzyme in modifying the physical properties of pulp and paper from Eucalyptus was tested (CelB treatment). An increase in mechanical strength of paper and a decrease in pulp dewatering properties were found, indicating that CelB treatment can be considered as a biorefining. Treatment with CelB gave rise to an improvement in paper strength similar to that obtained with 1,000 revolutions increase in mechanical refining. Comparison with the performances of recently developed endoglucanase A from the same strain and with a commercial cellulase showed that CelB produced the highest refining effect.

Cloning of a new endoglucanase gene from Bacillus sp. BP-23 and characterisation of the enzyme. Performance in paper manufacture from cereal straw.

The gene ce1A, encoding an endoglucanase from the strain Bacillus sp. BP-23, was cloned and expressed in Escherichia coli. The nucleotide sequence of a 1867-bp DNA fragment containing the ce1A gene was determined, revealing an open reading frame of 1200 nucleotides that encodes a protein of 44,803 Da. The deduced amino acid sequence of the encoded enzyme shows high homology to those of enzymes belonging to subtype 4 of the family-A cellulases. The ce1A gene product synthesized in E. coli showed activity on carboxymethylcellulose and lichenan but no activity was found on Avicel. Activity was enhanced in the presence of 10 mM Mg2+ and Ca2+ and showed its maximum at 40 degrees C and pH 4.0. Study of the performance of Ce1A on paper manufacture from agricultural fibres showed that treatment with the enzyme improved the properties of the pulp and the quality of paper. Ce1A treatment enhanced the physical properties (stretch and tensile index) of paper from wheat straw, while dewatering properties were slightly diminished. Electron-microscope analysis showed that the surface of straw fibres was modified by Ce1A.

Geographic distribution of French-Canadian low-density lipoprotein receptor gene mutations in the Province of Quebec.

A total of 35 homozygous and 1320 heterozygous patients with familial hypercholesterolemia (FH) was screened for the presence of six low-density lipoprotein receptor (LDLR) gene mutations previously reported among French-Canadians. The geographic distribution of patients' birthplaces and the relative prevalence of these six mutations in the LDLR gene in the province of Quebec were compared. For this purpose, the 16 administrative regions of the province of Quebec were grouped into seven geographic regions. The relative frequency of the six mutations differed in the seven regions: the > 15 kb deletion (delta > 15 kb) had the highest relative frequency in the Bas St-Laurent/Gaspésie region, and the point mutation in exon 3 had the highest relative frequency in the Saguenay-Lac-St-Jean/Côte-Nord region. In the Montreal area, the delta > 15 kb and the mutation in exon 3 had prevalence rates of 71.2% and 13.0%, respectively, whereas the relative frequencies of the delta > 15 kb and the point mutation in exon 3 in the Quebec city region were 57.5 and 21.8%, respectively. Finally, in Saguenay-Lac-St-Jean/Côte-Nord, the relative frequency of the delta > 15 kb only reached 31.5% and the point mutation in exon 3, 59.2%. Thus, on the north shore of the St. Lawrence River, the prevalence of the delta > 15 kb decreases from west to north-east, whereas the relative frequency of the mutation in exon 3 appears to increase. These observations provide a better characterization of FH among French-Canadians of Quebec, a Canadian province with a high prevalence of this inherited disease.

Heterozygous familial hypercholesterolemia in children: low-density lipoprotein receptor mutational analysis and variation in the expression of plasma lipoprotein-lipid concentrations.

The phenotypic expression of heterozygous familial hypercholesterolemia (FH) is variable form biochemical and clinical standpoints and several genetic and environmental factors could contribute to explain this variability. We have compared, in a cohort of 266 heterozygous FH children and adolescents (1-19 years), the variation in plasma lipoprotein-lipid levels among patients defined by three mutations in the low density lipoprotein receptor (LDLR) gene. Comparison of the plasma total and LDL-cholesterol (LDL-C) levels among the three mutation groups revealed significant differences. Plasma total and LDL-C levels were significantly higher (P < 0.05) in the group bearing the French-Canadian delta > 15 kb null allele mutation (8.17 +/- 1.45 and 6.58 +/- 1.42 mmol/l) and in the group with the defective allele C646Y missense mutation (8.18 +/- 1.53 and 6.65 +/- 1.50 mmo/l) compared to the group with the defective allele W66G missense mutation (7.19 +/- 1.23 and 5.62 +/- 1.16 mmol/l). Comparisons of other lipoprotein-lipid parameters between FH heterozygotes and normolipemic (n = 120) children indicated that all mutation groups had significantly (P = 0.0001) lower plasma HDL-cholesterol (HDL-C) levels and a higher total cholesterol (TC) to HDL-C ratio (P < 0.05). Among FH heterozygote groups, the W66G group had the lowest TC to HDL-C ratio. Multivariate analyses revealed that in FH heterozygotes as well as in controls, HDL-C levels contributed to a greater proportion of the variation in TC to HDL-C ratio than TC. In order to examine the age effect, control and FH heterozygote delta > 15 kb groups were then subdivided into four groups (1-4; 5-8; 9-13, and 14-19 years). The variation in HDL-C and triglycerides with age in heterozygous FH children showed a pattern which was similar to the one noted in the control group. In conclusion, the present study demonstrated that the overall contribution of age to variation in the lipoprotein profile of heterozygous FH children is similar to the effect observed among healthy children. The effect of LDLR gene in FH is dominant and there was no difference in plasma TC and LDL-C due to gender. Finally, this study indicates that the LDLR gene type mutations are a modulator of the magnitude of the increase in plasma TC and LDL-C levels noted among FH heterozygote children.

Rapid restriction fragment analysis for screening four point mutations of the low-density lipoprotein receptor gene in French Canadians.

Familial hypercholesterolemia (FH) has an estimated frequency of 1:154 among French Canadians in Northeastern Quebec, compared with 1:500 in most other populations. FH is caused by numerous mutations of the low-density lipoprotein (LDL) receptor gene, but only six well-characterized mutations are known to cause FH in French Canadians. High prevalence of the phenotype, along with a limited number of mutations in this population, provides a unique opportunity to study genotype-phenotype variation. Since the current methods for detection of point mutations in this population use complicated approaches, we report polymerase chain reaction (PCR)-based restriction fragment analysis to detect all four point mutations. This approach provides a rapid diagnosis and is suitable to screen large number of samples for studies in genetic epidemiology; it should be useful in identifying FH in other populations bearing the same mutations.

[Cidade Leonor slum, São Paulo. III. Environmental contamination and natural feeding practice]. / Observações sobre a favela da Cidade Leonor, São Paulo. III--Contaminação ambiental e a prática do aleitamento natural.

In this study the authors report the high rate of environmental contamination to which children living in slum areas are exposed. The authors performed a bacteriologic and parasitologic survey in children with acute diarrhea and in controls. Feeding habits were also recorded. The feeding habits revealed that 176 out of 520 children (33.8%) were never breast fed, whereas the remaining 344 (66.7%) were breast fed for an average of 2.2 months. The parasitologic survey was positive in 89% of the stool samples obtained from 83 children, mostly with multiple infections. The bacteriologic survey revealed the presence of enteropathogens and, in particular, invasive E. coli and Campylobacter in 46.7% of the children with acute diarrhea, and in 32.5% of the children in the control group. These findings allow the authors to state that environmental conditions of slum areas directly predispose to the appearance of the diarrhea-malnutrition binomial.

[Antibodies against Toxoplasma gondii in swine in Costa Rica: epidemiologic importance]. / Anticuerpos contra Toxoplasma gondii en cerdos de Costa Rica: importancia epidemiológica.

On a three hundred swine sera sample collected from a Municipal Slaughter house and a Research Laboratory at the Ministerio de Agricultura y Ganadería a 26% of positivity against T. gondii was found using the carbon immunoassay. A relationship between the age and swine race are made. The epidemiological significance of this findings are discussed focused mainly on the role of swine meat as a source of human infection in Costa Rica.