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R J Cox

Publications and source records attributed to R J Cox.

At least 37 records · Page 2Linked to original sources
PubMed1998

Randomized, controlled trial of video self-instruction versus traditional CPR training.

STUDY OBJECTIVE: We conducted a prospective, randomized, controlled trial to test the hypothesis that a 34-minute video self-instruction (VSI) training program for adult CPR would yield comparable or better CPR performance than the current community standard, the American Heart Association Heartsaver course. METHODS: Incoming freshman medical students were randomly assigned to VSI or the Heartsaver CPR course. Two to 6 months after training, we tested subjects to determine their ability to perform CPR in a simulated cardiac arrest setting. Blinded observers used explicit criteria to assess our primary outcome, CPR performance skill. In addition, we assessed secondary outcomes including sequential performance of individual skills, ventilation and chest compression characteristics, and written tests of CPR-related knowledge and attitudes. RESULTS: VSI trainees displayed superior overall performance compared with traditional trainees. Twenty of 47 traditional trainees (43%) were judged not competent in their performance of CPR, compared with only 8 of 42 VSI trainees (19%; absolute difference, 24%; 95% confidence interval, 5% to 42%). CONCLUSION: In a group of incoming freshman medical students, we found that a half-hour of VSI resulted in superior overall CPR performance compared with that in traditional trainees. If validated by further research, VSI may provide a simple, quick, and inexpensive alternative to traditional CPR instruction for health care workers and, perhaps, the general population.

Adult↗
PubMed1998

Catalytic self-acylation of type II polyketide synthase acyl carrier proteins.

BACKGROUND: Aromatic polyketides are synthesised in streptomycetes by the successive condensation of simple carboxylic acids, catalysed by multienzyme complexes--the polyketide synthases (PKSs). Polyketide assembly intermediates are covalently linked as thioesters to the holo-acyl carrier protein (ACP) subunit of these type II PKSs. The ACP is primed for chain elongation by the transfer of malonate from malonyl CoA. Malonylation of fatty acid synthase (FAS) ACPs is catalysed by specific malonyl transferase (MT) enzymes. The type II PKS gene clusters apparently lack genes encoding such MT proteins, however. It has been proposed that the MT subunit of the FAS in streptomycetes catalyses malonylation of both FAS and PKS ACPs in vivo. RESULTS: We demonstrate that type II PKS ACPs catalyse self-malonylation upon incubation with malonyl CoA in vitro. The self-malonylation reaction of the actinorhodin C17S holo-ACP has a K(m) for malonyl CoA of 219 microM and a kcat of 0.34 min-1. Complete acylation of the PKS ACPs was observed with malonyl, methylmalonyl and acetoacetyl CoAs. No reaction was observed with acetyl and butyryl CoAs and FAS ACPs did not react with any of the substrates. Recombinant FAS MT from Streptomyces coelicolor did not accelerate the rate of malonylation. CONCLUSIONS: The catalytic self-acylation of type II PKS ACPs is an unprecedented reaction. We propose a reaction mechanism in which conserved arginines form a salt bridge with the acyl moiety and sequester it from bulk solvent. This work suggests that the beta-ketoacyl synthase, chain length factor and ACP may constitute a truly minimal PKS in vivo.

Acyl Carrier Protein↗
PubMed1998

MCAT is not required for in vitro polyketide synthesis in a minimal actinorhodin polyketide synthase from Streptomyces coelicolor.

BACKGROUND: It has been proposed that Streptomyces malonyl CoA: holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. RESULTS: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar AC:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. CONCLUSIONS: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.

Acyl-Carrier Protein S-Malonyltransferase↗
PubMed1998

Systemic and mucosal immune responses in young children and adults after parenteral influenza vaccination.

The effect of natural mucosal priming on systemic and mucosal immune responses was investigated in young children after parenteral influenza vaccination. Eighteen young children and 8 adults were vaccinated with trivalent influenza vaccine at various time intervals before tonsillectomy. The influenza-specific IgG, IgA, and IgM immune responses were examined in tonsillar lymphocytes and frequent samples of peripheral blood and oral fluid. Young children were divided into primed and unprimed groups on the basis of presence of prevaccination serum antibodies. In peripheral blood, adults and primed children had significantly higher IgG and IgA antibody responses than did unprimed children. Irrespective of priming, children elicited weaker IgA responses than adults in both tonsils and oral fluid. While natural priming was essential to elicit strong systemic response in young children after parenteral influenza vaccination, it did not influence the local responses, which were significantly lower in both primed and unprimed children than in adults.

Adult↗
PubMed1997

Post-translational modification of heterologously expressed Streptomyces type II polyketide synthase acyl carrier proteins.

Expression in Escherichia coli of Streptomyces acyl carrier proteins (ACPs) associated with polyketide biosynthesis using the pT7-7 expression system of Tabor and Richardson led to the production predominantly of inactive apo-proteins lacking the 4'-phosphopantetheinyl prosthetic group essential for polyketide synthase activity. Modification of growth conditions led to an increase of production of active holo-protein for the actinorhodin (act) ACP, but this technique was ineffective for oxytetracycline (otc) and griseusin (gris) ACPs. Labelling experiments revealed that a low level of otc ACP expressed prior to induction was produced mainly as active holo-protein, while post-induction 15N-labelled protein was almost exclusively in the apo-ACP form. Limiting endogenous holo-acyl carrier protein synthase (ACPS) concentration was implicated as responsible for low apo-ACP to holo-ACP conversion, rather than limiting substrate (coenzyme A) and cofactor (Mg2+) concentrations. Co-expression of act and gris ACPs with ACPS in E. coli led to high levels of production of active holo-ACPs and ACPS. We have also made the significant observation that ACPS is able to transfer acylated CoA moieties to act apo-ACP.

Acyl Carrier Protein↗
PubMed1995

Cross-reaction but no avidity change of the serum antibody response after influenza vaccination.

Pre- and post-vaccination sera from 19 volunteers were analysed by the haemagglutination inhibition (HI) test, virus neutralization (VN) assay and avidity enzyme-linked immunosorbent assay (ELISA). The sera were tested against the three strains in a commercial inactivated influenza vaccine; A/Beijing/353/89(H3N2); A/Taiwan/1/86 (H1N1) and B/Yamagata/16/88. Additionally, a range of earlier strains and one newer isolate were assayed for HI- and VN-antibodies. Large variations in the pre-vaccination HI titres were observed for the viruses tested. However, 8-9 days after vaccination HI titres increased to above the assumed protective level (HI > or = 40) in most subjects. Although a limited number of patients were analysed at each sampling point, the time-profile we observed in this study is consistent with data we have obtained in earlier trials (Cox, R.J. et al., Vaccine 1994, 12,993-999). The VN titres, on the other hand, were low against all influenza strains before and up to 6 days, but increased rapidly 8-9 days after vaccination. A recent H3N2 isolate, A/Beijing/32/92 (H3N2), which had drifted further away from the vaccine strain, reacted to low titres or were negative in both the HI and VN assays. No change in the serum avidity to the influenza surface antigens was detected after vaccination, whereas sera from subjects naturally infected with influenza showed an increase in avidity to the infecting virus strain. The increase in serum avidity observed in the infected subjects is probably due to the increased and prolonged antigenic stimulus provided by the replicating virus.

Adolescent↗
PubMed1995

Parenteral influenza vaccination induces a rapid systemic and local immune response.

The kinetics of the local immune response in the upper respiratory tract to parenterally administered inactivated split trivalent influenza vaccine were examined in 19 healthy subjects. Influenza virus-specific antibody-secreting cells (ASC) could be detected as early as 2 days after vaccination in peripheral blood and tonsils, with a peak at approximately 1 week after vaccination and a decline to insignificant levels after 6 weeks. Circulating ASC produced IgG, IgA, and IgM, whereas ASC in tonsils produced mainly IgA and IgM. Influenza virus-specific antibodies were predominantly IgG and IgM in serum and IgA in oral fluid; they rose after 1 week and were elevated at 6 weeks. This may indicate a secretory involvement of the anti-influenza virus response in the upper respiratory tract. Parenteral influenza vaccination induced an immediate and significant immune response in both the upper respiratory tract and peripheral blood.

Adolescent↗
PubMed1994

An early humoral immune response in peripheral blood following parenteral inactivated influenza vaccination.

The enzyme-linked immunospot assay was used to examine the humoral immune response in 15 healthy volunteers immunized with either split or subunit inactivated trivalent influenza vaccine containing A/Beijing/353/89 (H3N2), A/Taiwan/1/86 (H1N1) and B/Yamagata/16/88. The rapidity of the individual B-cell and serum antibody response was examined in lymphocyte and serum samples collected at various time intervals after vaccination. A rapid serological response was detected with increases in antibody titre detected in the majority of volunteers by 7-8 days postvaccination. Influenza-specific plasma cells were detected as early as 4 days postvaccination, higher numbers of IgA and IgG antibody-secreting cells (ASC) were observed which peaked at 7-8 days postvaccination. The number of ASCs then declined, with low numbers of cells detected at 11 days postvaccination. Influenza-specific IgA ASCs were predominantly of the IgA1 subclass. This rapid immune response may have a bearing on future vaccination policies of unimmunized 'at risk groups' in times of high influenza activity.

Adult↗
PubMed1994

Attenuation of virulence in influenza B viral infection of volunteers.

A study was performed with volunteers in order to determine whether the virulence of an influenza B viral infection could be attenuated. Of a total of 62 persons, 26 received intranasal inoculations of an unpassaged influenza B virus isolate [virus U], while 26 received the same virus isolated passaged in cell culture and then in special pathogen-free embryonated hens' eggs [virus P]. The remaining 10 persons received uninoculated cell culture medium. Daily nasal wash samples were collected post-infection and scores for illness in the volunteers were evaluated. Viruses were isolated in cell culture and in eggs. Isolates were analysed by means of monoclonal antibodies (MAbs) raised against the influenza B viral haemagglutinin (HA) glycoprotein. One-step and nested polymerase chain reactions as well as direct nucleotide sequence analysis of part of the HA gene of the unpassaged specimens, together with the influenza B viruses isolated from those specimens, were performed. Nine of 26 volunteers who received the unpassaged virus became ill (illness scores from 13-84/100) whereas 7/26 of the volunteers who received the passaged virus had very mild illness (illness scores from 3-7/100). All the other volunteers remained well. Results of analysing the clinical specimens collected from the two groups of volunteers were compared. A difference in MAb reactivity, together with an aspartate for asparagine amino acid substitution at position 196 in a 432 base pair region of the viral HA gene, was observed. The loss of a potential glycosylation site at amino acid position 196-198 in the viral HA was associated with attenuation of virulence. This finding may have implications for the formulation of influenza vaccines.

Adult↗
PubMed1994

CompuTOD, a computer program to estimate time of death of deer.

A statistical program named CompuTOD has been written which calculates the time since death of white-tailed deer. The data used for the regression analysis (n = 378) was obtained from a controlled hunt in 1982. The results obtained compare favorably with previous studies but additionally gives upper and lower confidence limits for the calculated time interval since death.

Animals↗
PubMed1979

Localization of the parathyroid glands by intraoperative methylene blue staining.

Exploration of the neck for primary hyperparathyroidism has increased in our institution, as evidenced by nine patients treated in the past one year, as compared with six in the previous three years. Our experience indicates that methylene blue staining has served as an important adjunct in the localization of abnormal parathyroid glands. No complications were noted intraoperatively or postoperatively as a result of its use. Operating time was measurably decreased. The results of this study support the routine use of methylene blue in both primary and secondary parathyroid exploration, and this is currently being done in our institution.

Adenoma↗
PubMed1977

The effect of chronic anxiety level upon self control of heart rate.

A sample of 90 subjects were rated on the IPAT anxiety scale and 5 subjects (3 male and 2 female) per group were selected from each of the high and low anxiety categories. All subjects were naive participants in heart rate biofeedback sessions utilising analogue visual feedback. Following a heart rate baseline (no feedback) session, all subjects were required to raise their heart rate and lower their heart rate in two separate trials, a visual "target" criteria being provided. The data collected consisted of a resting baseline heart rate value, mean heart rate increase, and mean heart decrease values expressed as beats per minute. Results indicated a marked ability for highly anxious subjects to self-induce heart rate increases only and for low anxious subjects to decrease their heart rate only.

Anxiety↗
PubMed1975

Differentiation in Coprinus lagopus. III. Expansion of excised fruit-bodies.

Fruit-body expansion was studied in Coprinus lagopus (sensu Buller) following surgical procedures. Elongation occurred after denuding mushroom caps of essentially all peripheral scales. Young primordia (1 - 5 mm) failed to develop after vertical bisection. Older primordia (e.g. 10 mm) expanded 3 - 4 fold after vertical bisection or quadrisection, underwent autolysis and basidiospore production. An amorphous brown gel in the stripe lumen disappeared during development of bisected primordia. Stripes isolated from primordia expanded autonomously and exhibited negative geotropism when incubated upside down or when the stripe apex was removed. Displacement of charcoal particles dusted on intact stripes revealed the most active zone of expansion to be the upper mid-region of the stripe. Segmented stripes likewise showed most active elongation in the mid-region. Vertically bisected stripes also expanded.

Agaricales↗