Antiviral and Antibacterial 3D-Printed Products Functionalised with Poly(hexamethylene biguanide).

Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray coatings at public facilities are the typical measures taken to protect people from coronaviruses and other pathogens. However, limitations of human resources and coating durability, as well as the safety of disinfectants used are the major concerns in society during a pandemic. Non-leachable antimicrobial agent poly(hexamethylene biguanide) (PHMB) was mixed into photocurable liquid resins to produce novel and tailor-made covers for public facilities via digital light processing, which is a popular 3D printing technique for satisfactory printing resolution. Potent efficacies of the 3D-printed plastics were achieved in standard antibacterial assessments against S. aureus, E. coli and K. pneumoniae. A total of 99.9% of Human coronavirus 229E was killed after being in contact with the 3D-printed samples (containing the promising PHMB formulation) for two hours. In an eight-week field test in Hong Kong Wetland Park, antibacterial performances of the specially designed 3D-printed covers analysed by environmental swabbing were also found to be satisfactory. With these remarkable outcomes, antimicrobial products prepared by digital light processing 3D printing can be regarded as a reliable solution to long-term infection prevention and control.

Nasopharyngeal oxygen with intermittent nose-close and abdomen-compression: a novel resuscitation technique in a piglet model.

OBJECTIVE: To evaluate the efficacy of a simple and novel cardiopulmonary resuscitation (CPR) technique, nasopharyngeal oxygen with intermittent nose-close and abdomen-compression (NPO(2) -NC-AC) in an animal model. DESIGN: Prospective piglet study. SETTING: In an animal physiology laboratory of a medical university. PIGLETS: Six healthy piglets <14 days old. INTERVENTIONS: Spontaneous breathing of the anesthetized piglets (n = 6) was medically ceased until severe bradycardia (<20 beat/min). NPO(2) -NC-AC CPR trial was then initiated by delivering NPO(2) at 1.0-1.5 L/kg/min and intermittently performing the NC-AC maneuver: (1) NC for inspiration, occluded nostrils for 1 sec; and (2) AC for expiration, released nostrils, and compressed the abdomen for 1 sec. NC-AC was repeated at a rate of 30/min for 5 min. This CPR trial was repeated three times in each piglet. Cardiopulmonary variables were monitored, recorded, and compared. MEASUREMENTS AND MAIN RESULTS: A total of 18 CPR trials were performed. All of these acute life-threatening asphyxia events rapidly improved within 1 min of CPR. Cardiopulmonary variables recovered to the baseline levels and oxygenation continually increased. The intratracheal pressure (P(tr) ) values of positive end expiratory pressure and peak inspiratory pressure values were 4.3 ± 0.8 cmH(2) O and 26.2 ± 4.1 cmH(2) O, respectively. Chest wall movement was observed when the P(tr) reached 17.5 ± 3.1 cmH(2) O. All six piglets fully recovered after 63.8 ± 7.2 min of experiment without additional support. CONCLUSIONS: NPO(2) -NC-AC is a simple and effective CPR technique for severe acute cardiopulmonary asphyxia in piglets. It may be clinically applicable for supportive or rescue use.

A "GC-rich" method for mammalian gene expression: a dominant role of non-coding DNA GC content in regulation of mammalian gene expression.

High mammalian gene expression was obtained for more than twenty different proteins in different cell types by just a few laboratory scale stable gene transfections for each protein. The stable expression vectors were constructed by inserting a naturally-occurring 1.006 kb or a synthetic 0.733 kb DNA fragment (including intron) of extremely GC-rich at the 5' or/and 3' flanking regions of these protein genes or their gene promoters. This experiment is the first experimental evidence showing that a non-coding extremely GC-rich DNA fragment is a super "chromatin opening element" and plays an important role in mammalian gene expression. This experiment has further indicated that chromatin-based regulation of mammalian gene expression is at least partially embedded in DNA primary structure, namely DNA GC-content.