Browsing by Author "Castro, Felipe A."

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Serological prevalence and persistence of high-risk human papillomavirus infection among women in Santiago, Chile
    (2014) Castro, Felipe A.; Dominguez, Angélica; Puschel Illanes, Klaus; Van De Wyngard, Vanessa; Snijders, Peter J.; Franceschi, Silvia; Pawlita, Michael; Ferreccio Readi, Catterina; Castro, Felipe A.; Dominguez, Angélica; Puschel Illanes, Klaus; Van De Wyngard, Vanessa; Snijders, Peter J.; Franceschi, Silvia; Pawlita, Michael; Ferreccio Readi, Catterina
    Abstract Background Human papillomavirus (HPV) serology is a main factor for designing vaccination programs and surveillance strategies; nevertheless, there are few reports of HPV seroprevalence in the general population, especially in Latin America. This study aimed to describe high-risk HPV serological prevalence, persistence, and association with concurrent cervical infection, in Chilean women. Methods 1021 women from the general population, aged 15–85 years, were studied in 2001 of whom 600 were reexamined in 2006. The assessments at both time points included cervical HPV DNA testing, HPV antibody testing, cervical cytology and a sociodemographic/behavioral questionnaire. HPV DNA and antibodies against L1 protein of types 16, 18, 31, 33, 35, 45, 52, and 58 were assessed by reverse line blot and multiplex serology, respectively. Results Seropositivity was high at both baseline (43.2%) and follow-up (50.2%) and increased with age (p < 0.001); corresponding DNA prevalences were 6.7% and 8.7%. DNA and seroprevalence were associated at baseline (p = 0.01 for any HPV). Early age at first sexual intercourse and having had two or more sexual partners were independently associated with seropositivity. Most (82.0%) initially seropositive women remained seropositive at follow-up; 21.6% of initially seronegative women seroconverted, reaching 17.5% among women older than 60 years of age. ASCUS or worse cytology was correlated with HPV DNA positivity but not with HPV seropositivity. Conclusion HPV seroprevalence studies are a useful tool for learning about the dynamics of HPV infection in a community. This study contributes to understanding the natural history of HPV infection and provides a baseline assessment before the incorporation of HPV vaccination into a national program.
  • No Thumbnail Available
    Item
    Socioeconomic and environmental benefits of substituting firewood with charcoal briquettes produced from biomass residues in the Forestry Belt in Chile
    (2023) Chiang, Luciano E.; Castro, Felipe A.; Molina, Fernanda A.
    An assessment of the potential economic, environmental, and health benefits of substituting firewood with charcoal briquettes as heating fuel in cities located in the Forestry Belt in Chile is conducted. Experimental results obtained by the authors allowed to determine production yields and energy packing of charcoal briquettes obtained from Eucalyptus globulus and radiata pine residues. Given the large annual harvested surface of these two species, large quantities of residual biomass are left available at very low cost. The technology proposed to produce these charcoal briquettes is based in the process of pyrolysis in retort kilns. These give better results than traditional methods used until now in Chile to produce charcoal, but a higher technology level is required. Retort kilns rendered yield ratios of 0.247 and 0.286 [kg of charcoal/kg feedstock] for eucalyptus and radiata pine respectively. Charcoal briquettes gave a LHV (lower heating value) of 7836 kcal/kg and 7975 kcal/kg for eucalyptus and pine forest residues feedstock respectively, about twice that of dry firewood. Our economics analysis renders a cost of 0.1059 USD/kWh, which is competitive against firewood and other fuel options. In terms of health and environmental impact it is estimated that using charcoal briquettes from eucalyptus and pine harvested residues would reduce PM2.5 (particle matter <2.5 mu g) air pollution, the most critical source of contamination in this geographic region, around 7.96 %, saving annually an estimated 9376 tons from being delivered into the atmosphere. An estimated 8.3 % of the annual firewood consumption (966,656 m3/year of which 2/3 is native) would be saved, so that 2041 ha of native deforestation would be avoided.
  • No Thumbnail Available
    Item
    VEMERS 2.0: Upgrading of an Emergency Use Ventilator from a Single Mandatory Volume Control Mode of Ventilation (VEMERS 1.0) to 8 Modes of Ventilation
    (2022) Chiang, Luciano E.; Castro, Felipe A.; Sanchez, Tomas F.
    The upgrading of an emergency use ventilator from a single mandatory volume control mode of ventilation (VEMERS 1.0) to 8 modes of ventilation (VEMERS 2.0) is described. The original VEMERS 1.0 was developed in the midst of the COVID-19 crisis in Chile (April to August 2020) following special but nonetheless strict guidelines specified by local medical associations and national health and scientific ministries. The upgrade to 8 modes of ventilation in VEMERS 2.0 was made possible with minor but transcendental changes to the original architecture. The main contribution of this research is that starting from a functional block diagram of an ICU mechanical ventilator and carrying a systematic analysis, the main function blocks are implemented in such a way that combinations of standard off-the-shelf pneumatic and electronic components can be used. This approach has both economical and technical advantages. No special parts need to be fabricated at all, and because of a wider variety of options, the use of extensively field-proven off-the-shelf commercial components assures better availability and lower costs when compared to that of conventional ICU mechanical ventilators, without sacrificing reliability. Given the promising results obtained with VEMERS 2.0 in the subsequent national certification process, the production of 40 VEMERS 2.0 units was sponsored by the Ministry of Science and the Ministry of Economy. Twenty units have been distributed among hospitals along the country. The purpose of VEMERS 2.0, as a low-cost but very reliable option, is to increase the number of mechanical ventilators available (3,000 for a population of 18,000,000) in the country to eventually reach a ratio similar to that of more developed countries. VEMERS is an open-source project for others to use the knowledge gained.
  • No Thumbnail Available
    Item
    VEMERS UC: A Clinically Validated Emergency Mechanical Ventilator for COVID-19 and Postpandemic Use in Low Resource Communities
    (2021) Chiang, Luciano E.; Castro, Felipe A.
    In this article, we present a clinically validated invasive emergency mechanical ventilator developed in Chile called VEMERS UC. It has been clinically tested and validated in intubated Covid-19 patients. Once the pandemic hit Chilean soil in March 2020, it was quite clear that the number of mechanical ventilators available would not be enough. As in other parts of the world many initiatives sprung, most of them naively simple. Chilean medical societies joined engineering specialists and agreed early on in an organized and regulated open process for validating emergency mechanical ventilators, thus allowing for rapid development but with the required functionality, reliability, and safety features. VEMERS UC was one of a few that completed successfully all stages of the validating process, the final test being on five critically ill intubated Covid-19 patients for eight hours each. VEMERS UC is based on an electropneumatic circuit architecture, and its components are all low cost, off-the-shelf pneumatic, and electronic products easily obtained in industrial markets. It works in continuous mandatory volume control mode. The novel technical features of VEMERS UC are discussed here as well as the results obtained in each stage of the validating process. The validating process carried out in Chile is noteworthy by itself, and it could be used as an example in other developing countries. Furthermore, VEMERS UC can be used as a guiding design reference in other countries as well, since this design has already been thoroughly tested in human patients and has proven to work successfully.