Background Frontline health care workers, including physicians, are at high risk of contracting coronavirus disease (COVID-19) owing to their exposure to patients suspected of having COVID-19. Objective The aim of this study was to evaluate the benefits and feasibility of a double triage and telemedicine protocol in improving infection control in the emergency department (ED). Methods In this retrospective study, we recruited patients aged ≥20 years referred to the ED of the National Taiwan University Hospital between March 1 and April 30, 2020. A double triage and telemedicine protocol was developed to triage suggested COVID-19 cases and minimize health workers’ exposure to this disease. We categorized patients attending video interviews into a telemedicine group and patients experiencing face-to-face interviews into a conventional group. A questionnaire was used to assess how patients perceived the quality of the interviews and their communication with physicians as well as perceptions of stress, discrimination, and privacy. Each question was evaluated using a 5-point Likert scale. Physicians’ total exposure time and total evaluation time were treated as primary outcomes, and the mean scores of the questions were treated as secondary outcomes. Results The final sample included 198 patients, including 93 cases (47.0%) in the telemedicine group and 105 cases (53.0%) in the conventional group. The total exposure time in the telemedicine group was significantly shorter than that in the conventional group (4.7 minutes vs 8.9 minutes, P<.001), whereas the total evaluation time in the telemedicine group was significantly longer than that in the conventional group (12.2 minutes vs 8.9 minutes, P<.001). After controlling for potential confounders, the total exposure time in the telemedicine group was 4.6 minutes shorter than that in the conventional group (95% CI −5.7 to −3.5, P<.001), whereas the total evaluation time in the telemedicine group was 2.8 minutes longer than that in the conventional group (95% CI −1.6 to −4.0, P<.001). The mean scores of the patient questionnaire were high in both groups (4.5/5 to 4.7/5 points). Conclusions The implementation of the double triage and telemedicine protocol in the ED during the COVID-19 pandemic has high potential to improve infection control.

The hypothesis that translation Qf the ilvD and ilvA genes of Escherichia coli may be linked has been examined ip strains in which lacZ-ilvD protein fusions are translated in all three reading frames with respect to ilvD. In these strains, the nucleotide sequence was altered to obtain premature termination of ilvD translation, and in one strain translation termination of ilvO DNA occurred two bases downstream of the ilvA initiation codon. In the wild-type strain, the ilvD translation termination site was located two bases upstream of the ilvA start codon. In each of the mutant strains, expression of ilvA, as determined by the level of threonine deaminase activity, was strikingly lower than in the wild-type strain. The data suggest that expression of ilvD and ilvA is translationally coupled. By inserting a promoterless cat gene downstream of ilvA, it was shown that the differences in enzyme activity were not the result of differences in the amount of ilvA mRNA produced.In members of the family Enterobacteriaceae, the biosynthesis of isoleucine and valine occurs by parallel pathways with enzymes specified by a cluster of genes, ilvGMEDA YC (39). The first five genes in the cluster form the ilvGMEDA operon; ilvY and ilvC are separate transcriptional units. Blazey and Burns (4) first implicated regulation at the translational level in the ilv operon and raised the possibility of translational coupling. Their experiments showed that TnJO insertions in both orientations in the ilvD gene of Salmonella typhimurium exerted an absolute polarity on ilvA expression. In Escherichia coli, a similar strong polar effect has been demonstrated in strains containing bacteriophage Mu-1 insertions (32) or Tn5 insertions (3). Even earlier, it had been noted that the ilvlI188 ochre mutation resulted in a 60% reduction in threonine deaminase activity, although at the time, the effect was thought to be "antipolar" (42).Nucleotide s'equence analysis has revealed that the ilvD translation stop codon and'ilvA start codon are separated by 2 bases, TAA-TA-ATG (8, 18). (In this paper, we use the phrase "n bases upstream [or downstream]" to indicate that n bases separate the stop and start codons.) Proximity of translational termination and initiation signals, including overlapping signals, has been described as a feature in coupling translation of adjacent genes (11,24,33,35). Translational coupling has been reported for a number of gene pairs, including galK-galT (29), trpD-trpE (26), and trpB-trpA (1, 9). In this paper we present evidence that efficient translation of the downstream ilvA gene is dependent on translation of the upstream ilvD gene. MATERIALS AND METHODSBacterial strains and plasmids. The bacterial strains used in this study and their sources are listed in Table 1. The preparation of some of the strains requires special mention. Strain CU1644 was prepared by replacing the wild-type ilv region of CU1318 with that in pPU316, which carries AU(i'G-Y)2243::aad'. The aad+ gene, inserted at the site of the ilv deletion, was derived f...

Three different approaches were used to examine the regulatory effects of the amino acids specified by the peptide-coding region of the leader transcript of the ilvGMEDA operon of Escherichia coli K-12. Gene expression was examined in strains carrying an ilvGMED'-lac operon fusion. In one approach, auxotrophic derivatives were starved of single amino acids for brief periods, and the burst of j-galactosidase synthesis upon adding the missing amino acid was determined. Auxotrophic derivatives were also grown for brief periods with a limited supply of one amino acid (derepression experiments). Finally, prototrophic strains were grown in minimal medium supplemented with single and multiple supplements of the chosen amino acids. Although codons for arginine, serine, and proline are interspersed among the codons for the three branched-chain (regulatory) amino acids, they appeared to have no effect when added in excess to prototrophs or when supplied in restricted amounts to auxotrophs. Deletions removing the terminator stem from the leader removed all ilvspecific control, indicating that the attenuation mechanism is the sole mechanism for ilv-specific control.The specific control of expression of the ilvGMEDA operon in the enteric bacteria is characterized by repression of the operon when the three branched-chain amino acids are in ample supply but derepression when the supply of any one of the three is limited (14,30). This ilv-specific regulation appears to be exclusively a consequence of an attenuation mechanism ( Fig. 1) (4,32,38). In principle, the attenuation mechanism controlling the ilv operon appears to be quite similar to that found to control operons involved in tryptophan (35), leucine (19), phenylalanine (61), histidine (3), and threonine (17) biosynthesis: the leader region specifies a short peptide containing a disproportionate frequency of the amino acids that are found to regulate the operon. Thus, the rate at which the leader can be translated serves to sense whether the regulatory amino acid is in short or ample supply.As emphasized by Landick and Yanofsky (31), an important feature of the attenuation mechanism is the pausing of RNA polymerase at a certain site in the leader region. The pause allows time for the ribosome to initiate translation, and as translation proceeds, the base pairing in the protector (1:2 stem, Fig. 2) is progressively disrupted. Should ribosome movement be retarded, presumably by stalling at a regulatory codon, long enough for the bases in the upstream arm of the terminator (bases 157 to 164) to emerge on the nascent transcript, these bases can pair with those in the downstream arm of the protector (bases 98 to 105) in the antiterminator (2:3 stem, Fig. 3). It is assumed that, in the absence of ribosome stalling (repressing conditions), translation proceeds rapidly enough that the bases in the downstream arm of the protector will also be covered by the ribosome or otherwise be sterically prevented from antiterminator formation and the terminator will be formed instead. Altho...

The specificity of regulation by attenuation of the ilvGMEDA operon of Escherichia coli was examined by making alterations in the peptide-coding portion of the leader region. The effects of the alterations on attenuation control were monitored by operon fusions with the lacZ or cat gene. Substitution of the tandem leucine codons with arginine codons did not result in arginine control of attenuation even though the altered leader transcripts contained three consecutive arginine codons. Substitution of the single leucine codon with a proline codon at position 10 of the putative peptide, which had been shown to be important in the regulation of the Serratia marcescens ilv operon, did not result in control of attenuation by proline. Since the formation of neither proline nor arginine biosynthetic enzymes is regulated by attenuation control, the effect of tandem phenylalanine codons in place of the tandem leucine codons was examined and found not to result in control by phenylalanine supply. The latter failure may have been due to a configuration in the secondary structure of the protector stem of the leader transcript different from that of the wild-type transcript. The results of the study favored the idea that the lead ribosome does not initiate translation of the leader transcript until after the RNA polymerase has reached the pause site (117 bases into the leader region).

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