Toward the prevention of coronavirus infection: what role can polymers play?

Severe acute respiratory syndrome-associated coronavirus 2 has caused a global public health crisis with high rates of infection and mortality. Treatment and prevention approaches include vaccine development, the design of small-molecule antiviral drugs, and macromolecular neutralizing antibodies. Polymers have been designed for effective virus inhibition and as antiviral drug delivery carriers. This review summarizes recent progress and provides a perspective on polymer-based approaches for the treatment and prevention of coronavirus infection. These polymer-based partners include polyanion/polycations, dendritic polymers, macromolecular prodrugs, and polymeric drug delivery systems that have the potential to significantly improve the efficacy of antiviral therapeutics.

Flanking sequence specificity determines coding microsatellite heteroduplex and mutation rates with defective DNA mismatch repair (MMR).

The activin type II receptor (ACVR2) contains two identical microsatellites in exons 3 and 10, but only the exon 10 microsatellite is frameshifted in mismatch repair (MMR)-defective colonic tumors. The reason for this selectivity is not known. We hypothesized that ACVR2 frameshifts were influenced by DNA sequences surrounding the microsatellite. We constructed plasmids in which exons 3 or 10 of ACVR2 were cloned +1 bp out of frame of enhanced green fluorescent protein (EGFP), allowing -1 bp frameshift to express EGFP. Plasmids were stably transfected into MMR-deficient cells, and subsequent non-fluorescent cells were sorted, cultured and harvested for mutation analysis. We swapped DNA sequences flanking the exon 3 and 10 microsatellites to test our hypothesis. Native ACVR2 exon 3 and 10 microsatellites underwent heteroduplex formation (A(7)/T(8)) in hMLH1(-/-) cells, but only exon 10 microsatellites fully mutated (A(7)/T(7)) in both hMLH1(-/-) and hMSH6(-/-) backgrounds, showing selectivity for exon 10 frameshifts and inability of exon 3 heteroduplexes to fully mutate. Substituting nucleotides flanking the exon 3 microsatellite for nucleotides flanking the exon 10 microsatellite significantly reduced heteroduplex and full mutation in hMLH1(-/-) cells. When the exon 3 microsatellite was flanked by nucleotides normally surrounding the exon 10 microsatellite, fully mutant exon 3 frameshifts appeared. Mutation selectivity for ACVR2 lies partly with flanking nucleotides surrounding each microsatellite.

Studies of MEMS Acoustic Sensors as Implantable Microphones for Totally Implantable Hearing-Aid Systems.

There is a need for high-quality implantable microphones for existing semiimplantable middle-ear hearing systems and cochlear prosthesis to make them totally implantable, thus overcoming discomfort, inconvenience, and social stigma. This paper summarizes and compares the results of an in-vitro study on three design approaches and the feasibility of using microelectromechanical system acoustic sensors as implantable microphones to convert the umbo vibration directly into a high-quality sound signal. The requirements of sensors were selected including the ability to withstand large body shocks or sudden changes of air pressure. Umbo vibration characteristics were extracted from literature and laboratory measurement data. A piezoelectric vibration source was built and calibrated to simulate the umbo vibration. Two laboratory models of the acoustic sensor were studied. The model-A device, using electrets-microphone as the sensor, was designed and tested in the laboratory and on temporal bones. The results verify that the laboratory measurement is consistent with the temporal bone characterization and achieves a near flat frequency response with a minimum detectable signal of a 65-dB sound-pressure-level (SPL) at 1 kHz. The model-B sensor was then designed to increase the sensitivity and provide an easy mounting on umbo. The model-B device can detect 40-dB SPL sound in the 1-2 kHz region, with 100-Hz channel bandwidth. The results of model-A and model-B displacement sensors and the acceleration sensor are summarized and compared. A preliminary design of the implantable displacement sensor for totally implantable hearing-aid systems is also presented.

A highly atom efficient, solvent promoted addition of tetraallylic, tetraallenic, and tetrapropargylic stannanes to carbonyl compounds.

Tetraallylic, tetraallenic, and tetrapropargylic stannanes (0.25 equiv) react with aldehydes in methanol to provide unsaturated alcohols in good to excellent yields (56-99%). These reactions proceed exclusively with allylic rearrangement for tetra(2-butenyl)tin 2b and tetra(1,2-butadienyl)tin 16c and predominantly with allylic rearrangement for tetrapropadienyltin 16a and tetra(2-butynyl)tin 6e. Allylation reactions also proceeded smoothly with reactive ketones such as ethyl pyruvate (9a) and cyclohexanone (9b). The corresponding TFA-catalyzed reactions of dimethyl acetals 4d and 4e are regiospecific with allylic rearrangement.

Mechanism of pressure-induced gelation of milk.

The pressure-induced gelation of concentrated skimmed milk and milk-sugar mixtures was studied to discover the main components responsible for gelation. The major protein component responsible for gelation is micellar casein. Gelation occurs at similar pressures to casein micelle disintegration in dilute milk, and both can be prevented by inclusion of excess calcium chloride. Transmission electron micrographs show that the protein network is formed from particles with diameters approximately an order of magnitude smaller than those of intact casein micelles. Gelation occurs on decompression and is found to be baroreversible. Concentrations of sugar up to 30% reduce the critical concentration of casein required for gelation, but higher sugar concentrations inhibit gelation. A mechanism of gelation based on the aggregation of casein submicelles formed by pressure-induced disintegration of casein micelles is proposed. Observations on the effect of sucrose on gelation are discussed in terms of the influence of sugars on the solvent quality in aqueous casein systems.

High-pressure synthesis of enantiomerically pure C-6 substituted pyrazol.

The synthesis of enantiomerically pure C-6 substituted pyrazolo[3,4-d]pyrimidines has been performed by aromatic nucleophilic substitution of 4-amino-6-chloro-1-phenylpyrazolo[3,4-rd]pyrimidine under conditions of high pressure at ambient temperature. Conventional synthetic conditions (reflux at atmospheric pressure) were unsuccessful. The S enantiomer 11 displayed higher affinity and selectivity for the adenosine A1 receptor than the R enantiomer 12.

Stability and DNA alkylation rates of the simplest functional analogues of CC-1065, para-hydroxy and para-amino phenethyl bromides.

We have recently synthesised a series of compounds based on the simplest functional unit of CC-1065 containing a para substituted phenethyl halide moiety. These compounds alkylate N3 of adenines in a similar fashion to CC-1065, as well as N7 of guanines to a limited extent. In this work we compared the para amino substituted derivative (2) with the published hydroxyl compound (1) in terms of stability, DNA reactivity and pH dependence using gel electrophoresis techniques. The results show that 2 has a shorter lifetime and is at least 2.5 times more reactive with DNA than 1. It is completely hydrolysed between 30 and 60 min in buffer and its reaction with DNA is complete within 5 min. In contrast, only a fraction of 1 is hydrolysed after 60 min and retains reactivity towards DNA even after 3 h. The reactivities of both 1 and 2 with DNA are pH dependent and reaction rates rapidly decrease in the range pH 5.8-8.8. Preliminary molecular modelling studies suggest that the p-amino group on 2 enables the drug to bind to the AT-rich minor groove more effectively, thus stabilising the orientation of the substrate in the groove such that the reactive cyclopropyl ring is located close to the nucleophilic centre N3 of adenine. A possible mechanism of action of these drugs is presented based on these findings.

A Schizosaccharomyces pombe artificial chromosome large DNA cloning system.

The feasibility of using the fission yeast, Schizosaccharomyces pombe , as a host for the propagation of cloned large fragments of human DNA has been investigated. Two acentric vector arms were utilized; these carry autonomously replicating sequences ( ars elements), selectable markers ( ura4(+) or LEU2 ) and 250 bp of S. pombe terminal telomeric repeats. All cloning was performed between the unique sites in both vector arms for the restriction endonuclease Not I. Initially the system was tested by converting six previously characterized cosmids from human chromosome 11p13 into a form that could be propagated in S.pombe as linear episomal elements of 50-60 kb in length. In all transformants analysed these cosmids were maintained intact. To test if larger fragments of human DNA could also be propagated total human DNA was digested with Not I and size fractionated by pulsed field gel electrophoresis (PFGE). Fractions of 100-1000 kb were ligated to Not I-digested vector arms and transformed into S.pombe protoplasts in the presence of lipofectin. Prototrophic ura+leu+transformants were obtained which upon examination by PFGE were found to contain additional linear chromosomes migrating at between 100 and 500 kb with a copy number of 5-10 copies/cell. Hybridization analyses revealed that these additional bands contained human DNA. Fluorescent in situ hybridization (FISH) analyses of several independent clones indicated that the inserts were derived from single loci within the human genome. These analyses clearly demonstrate that it is possible to clone large fragments of heterologous DNA in fission yeast using this S.p ombe artificial chromosome system which we have called SPARC. This vector-host system will complement the various other systems for cloning large DNA fragments.

Test for equality of intraclass correlation coefficients under unequal family sizes.

The likelihood ratio test, the large-sample z-test, and the large-sample z-test have been proposed to test for the equality of two intraclass correlation coefficients under unequal family sizes based on two independent multinomial samples. It has been found on the basis of simulation studies that the likelihood ratio test consistently and reliably produces results superior to those of the large-sample z-test and large-sample z-test in terms of power for various combinations of intraclass correlation coefficient values.

Traumatic aortic transections: eight-year experience with the "clamp-sew" technique.

BACKGROUND: Because traumatic aortic transection is associated with high mortality rates, great debate exists about the appropriate operative technique for treatment of patients who have acute traumatic aortic transection. METHODS: To determine the safety and efficacy of the "clamp-sew" method, we retrospectively reviewed our 8-year experience treating 75 patients who had aortic injuries secondary to blunt trauma. Seventy-one of these patients were treated surgically. The clamp-sew method was used in all of these operations. RESULTS: Aortic cross-clamp time averaged 24 minutes (range, 14 to 36 minutes), with 4/71 having times in excess of 30 minutes. One patient (clamp time, 28 minutes) became paraplegic. Significant associated injuries were seen in 51/75 patients (48/71 patients with operation), including intrathoracic (35 patients), orthopedic (28 patients), intraabdominal (24 patients), and central nervous system (17 patients) damage. No patient died within 24 hours of operation. Overall 30-day mortality was 12% (9/75), with 7/9 having two or more aforementioned associated injuries. Of these 7, 5 had central nervous system injuries. Two of 9 died within 30 days without two or more associated injuries: 1 Jehovah's Witness of low hemoglobin, and 1 patient of sepsis. CONCLUSIONS: Although any of several maneuvers may be appropriate in managing traumatic aortic injuries, the simple "clamp-sew" technique is a safe and effective method for the treatment of traumatic aortic transections.

Alcohol advertising bans and alcohol abuse.

Henry Saffer [Saffer (1991) Journal of Health Economics 10, 65-79] concludes that bans on broadcast advertising for alcoholic beverages reduce total alcohol consumption, motor vehicle fatalities, and cirrhosis deaths. A reexamination of his data and procedures reveals a number of flaws. First, there is evidence of reverse causation: countries with low consumption/death rates tend to adopt advertising bans, creating a (spurious) negative correlation between bans and consumption/death rates. Second, even this correlation largely disappears when the estimates are corrected for serial correlation. Third, estimates based on the components of consumption--spirits, beer and wine--mostly indicate that bans are associated with increased consumption.

Effectiveness of a case management program.

Legislation of a case management service provided an opportunity to conduct a natural experiment exploring questions about implementation and effectiveness of case management services. A sample of 21 case managed and 21 comparison clients was interviewed using a protocol adapted from the Quality of Life Questionnaire (Fixed Response Alternative version). Results indicate that case managed clients received more services and had fewer unmet service needs. Quality of life was greater for case managed clients, hospital utilization was reduced, and a possible relationship among services, quality of life, and hospital utilization was identified.

Implementation and effectiveness of a bed reduction project.

A legislative mandate to shift a cohort of patients from the state hospital into intensive community treatment created an opportunity to explore questions about the impact of intensive community treatment on hospital utilization and quality of life. Information on prior and subsequent hospital utilization was taken from the state client information system. Information on community services and quality of life was obtained by interviewing clients in their homes, interviewing others who knew the clients, and by making direct observations of the clients' circumstances. Twenty-five of the intensively served clients were interviewed two to three months after discharge, as were 17 comparable clients who did not receive the intensive services. Clients did, in fact, receive more and better community services, their quality of life was better, and hospital utilization was dramatically reduced for both the targeted clients and the entire county catchment area.

Calcium mobilization in activated mast cells monitored by flow cytometric analysis.

Changes in intracellular calcium levels induced in mast cells by either antigen or ionomycin were monitored using flow cytometry and the calcium binding dye indo-1. Both stimuli increased calcium levels in responsive cells by a similar amount, but not all cells examined were responsive to antigen. Antigen-induced increases in intracellular calcium levels could be completely blocked by the calcium antagonist TMB-8. Flow cytometry appears to be a useful method for monitoring mast cell calcium concentrations, as it provides the capability to study large numbers of individual cells.

Methemoglobinemia: the hidden diagnosis.

Although methemoglobinemia is not commonly seen in the ER or the critical care setting, it can be life threatening if unrecognized and left untreated. A detailed case history illustrates the symptoms and some of the possible precipitating factors, and outlines treatment for a successful patient outcome.

Educational attainment and cohort size.

"We argue that the postwar baby boom [in the United States] caused substantial fluctuations in both the economic rewards to education and educational attainment over the last 3 decades. If substitutability between young and old workers diminishes with education, the present value of lifetime earnings for a boom cohort is depressed more for highly educated workers, reducing incentives for educational attainment. The opposite is true for pre- and postboom cohorts. The diminishing substitutability hypothesis explains the declines in both the returns to college and college completion rates in the 1970s and predicts a substantial increase in educational attainment for postboomers."

A further example of the low frequency antigen Pta.

The third Pt(a+) family is described and it has been shown that the red cell antigen is denatured when treated with proteolytic enzymes, but unaffected by neuraminidase and 2-aminoethylisothiouronium bromide treatment.