A Personal Respirator to Improve Protection for Healthcare Workers Treating COVID-19 (PeRSo)

Introduction: SARS-CoV-2 infection is a global pandemic. Personal Protective Equipment (PPE) to protect healthcare workers has been a recurrent challenge in terms of global stocks, supply logistics and suitability. In some settings, around 20% of healthcare workers treating COVID-19 cases have become infected, which leads to staff absence at peaks of the pandemic, and in some cases mortality.

Methods: To address shortcomings in PPE, we developed a simple powered air purifying respirator, made from inexpensive and widely available components. The prototype was designed to minimize manufacturing complexity so that derivative versions could be developed in low resource settings with minor modification.

Results: The “Personal Respirator – Southampton” (PeRSo) delivers High-Efficiency Particulate Air (HEPA) filtered air from a battery powered fan-filter assembly into a lightweight hood with a clear visor that can be comfortably worn for several hours. Validation testing demonstrates that the prototype removes microbes, avoids excessive CO₂ build-up in normal use, and passes fit test protocols widely used to evaluate standard N95/FFP2 and N99/FFP3 face masks. Feedback from doctors and nurses indicate the PeRSo prototype was preferred to standard FFP2 and FFP3 masks, being more comfortable and reducing the time and risk of recurrently changing PPE. Patients report better communication and reassurance as the entire face is visible.

Conclusion: Rapid upscale of production of cheaply produced powered air purifying respirators, designed to achieve regulatory approval in the country of production, could protect healthcare workers from infection and improve healthcare delivery during the COVID-19 pandemic.

Acid sensitive background potassium channels K2P3.1 and K2P9.1 undergo rapid dynamin-dependent endocytosis

Acid-sensitive, two-pore domain potassium channels, K(2P)3.1 and K(2P)9.1, are implicated in cardiac and nervous tissue responses to hormones, neurotransmitters and drugs. K(2P)3.1 and K(2P)9.1 leak potassium from the cell at rest and directly impact membrane potential. Hence altering channel number on the cell surface drives changes in cellular electrical properties. The rate of K(2P)3.1 and K(2P)9.1 delivery to and recovery from the plasma membrane determines both channel number at the cell surface and potassium leak from cells. This study examines the endocytosis of K(2P)3.1 and K(2P)9.1. Plasma membrane biotinylation was used to follow the fate of internalized GFP-tagged rat K(2P)3.1 and K(2P)9.1 transiently expressed in HeLa cells. Confocal fluorescence images were analyzed using Imaris software, which revealed that both channels are endocytosed by a dynamin-dependent mechanism and over the course of 60 min, move progressively toward the nucleus. Endogenous endocytosis of human K(2P)3.1 and K(2P)9.1 was examined in the lung carcinoma cell line, A549. Endogenous channels are endocytosed over a similar time-scale to the channels expressed transiently in HeLa cells. These findings both validate the use of recombinant systems and identify an endogenous model system in which K(2P)3.1 and K(2P)9.1 trafficking can be further studied.

N-glycosylation-dependent control of functional expression of background potassium channels K2P3.1 and K2P9.1

Two-pore domain potassium (K(2P)) channels play fundamental roles in cellular processes by enabling a constitutive leak of potassium from cells in which they are expressed, thus influencing cellular membrane potential and activity. Hence, regulation of these channels is of critical importance to cellular function. A key regulatory mechanism of K(2P) channels is the control of their cell surface expression. Membrane protein delivery to and retrieval from the cell surface is controlled by their passage through the secretory and endocytic pathways, and post-translational modifications regulate their progression through these pathways. All but one of the K(2P) channels possess consensus N-linked glycosylation sites, and here we demonstrate that the conserved putative N-glycosylation site in K(2P)3.1 and K(2P)9.1 is a glycan acceptor site. Patch clamp analysis revealed that disruption of channel glycosylation reduced K(2P)3.1 current, and flow cytometry was instrumental in attributing this to a decreased number of channels on the cell surface. Similar findings were observed when cells were cultured in reduced glucose concentrations. Disruption of N-linked glycosylation has less of an effect on K(2P)9.1, with a small reduction in number of channels on the surface observed, but no functional implications detected. Because nonglycosylated channels appear to pass through the secretory pathway in a manner comparable with glycosylated channels, the evidence presented here suggests that the decreased number of nonglycosylated K(2P)3.1 channels on the cell surface may be due to their decreased stability.

The pathway of cross-presentation is influenced by the particle size of phagocytosed antigen

Cross-presentation is the presentation by MHC class I of antigenic peptides from exogenous proteins that have been internalized and processed by professional antigen-presenting cells, e.g. dendritic cells. We have investigated the influence of particle size and antigen load on cross-presentation following antigen delivery on microspheres (MS). Cross-presentation from small particles (0·8-μm) is sensitive to proteasome inhibition and the blockade of endoplasmic reticulum-resident MHC class I complex export, whereas cross-presentation from larger particles (aggregated clumps of 0·8-μm MS) is resistant to these antagonists. This observation may have been overlooked previously, because of the heterogeneity of particle size and MS uptake in unsorted dendritic cell populations. Larger particles carry more antigen, but we show that antigen load does not influence the cross-presentation pathway used. Whereas early endosome autoantigen 1 (EEA1) could be observed in all phagosomes, we observed endoplasmic reticulum SNARE of molecular weight 24 000 (ERS24) and cathepsin S in association with 3·0-μm and aggregated 0·8-μm MS, but not individual 0·8-μm MS. A potential mechanism underlying our observations may be the activation of β-catenin by disruption of E-cadherin-mediated adhesion. Activated β-catenin was detected in the cytoplasm of cells after phagocytosis of MS (highest levels for the largest particles). We propose that particle size can direct the use of different pathways for the cross-presentation of an identical antigen. Furthermore, these pathways have differing yields of MHC class I-peptide complexes, which is an important variable in designing vaccination strategies for maximal antigen expression and CD8(+) T-cell priming.

Protein kinase A is central for forward transport of two-pore domain potassium channels K2P3.1 and K2P9.1

Acid-sensitive two-pore domain potassium channels (K2P3.1 and K2P9.1) play key roles in both physiological and pathophysiological mechanisms, the most fundamental of which is control of resting membrane potential of cells in which they are expressed. These background "leak" channels are constitutively active once expressed at the plasma membrane, and hence tight control of their targeting and surface expression is fundamental to the regulation of K(+) flux and cell excitability. The chaperone protein, 14-3-3, binds to a critical phosphorylated serine in the channel C termini of K2P3.1 and K2P9.1 (Ser(393) and Ser(373), respectively) and overcomes retention in the endoplasmic reticulum by βCOP. We sought to identify the kinase responsible for phosphorylation of the terminal serine in human and rat variants of K2P3.1 and K2P9.1. Adopting a bioinformatic approach, three candidate protein kinases were identified: cAMP-dependent protein kinase, ribosomal S6 kinase, and protein kinase C. In vitro phosphorylation assays were utilized to determine the ability of the candidate kinases to phosphorylate the channel C termini. Electrophysiological measurements of human K2P3.1 transiently expressed in HEK293 cells and cell surface assays of GFP-tagged K2P3.1 and K2P9.1 enabled the determination of the functional implications of phosphorylation by specific kinases. All of our findings support the conclusion that cAMP-dependent protein kinase is responsible for the phosphorylation of the terminal serine in both K2P3.1 and K2P9.1.

Utilization of allopurinol in the Australian community

BACKGROUND

International data suggest that suboptimal use of allopurinol is common. Allopurinol dose should be lower in renal impairment, but higher when gout is not controlled. The aim of the study was to examine trends in the usage of allopurinol in the Australian community.

METHODS

Community dispensing data on the urate-lowering drugs allopurinol and probenecid were obtained from databases kept by Medicare Australia and the Drug Utilization Sub-Committee, for January 1992 to December 2005.

RESULTS

Allopurinol comprised 98.4% of all prescriptions for urate-lowering drugs dispensed during 2005. Most prescriptions were for allopurinol 300 mg, but there was a steady shift towards use of allopurinol 100 mg in all states and territories over the period of the study. There were marked variations in prescribing rates across the country. New South Wales had the highest rate of subsidized prescribing for allopurinol 300 mg (39.3 per 1000 population). Tasmania had the highest rate for allopurinol 100 mg (14.3 per 1000 population), which coincided with an educational programme to decrease allopurinol dose in patients with renal impairment. Prescribing rates in the Northern Territory were substantially lower than all other regions, at 10.8 and 3.3 prescriptions per 1000 population for allopurinol 300 and 100 mg, respectively.

CONCLUSION

The increased uptake of allopurinol 100 mg suggests greater adherence to dosing guidelines and that there is value in educational programmes to optimize drug usage. Variability in utilization rates across regions indicates the need for research on factors responsible. Precise understanding of dosing trends requires access to deidentified, individual dosing data.

Polymer microarrays: identification of substrates for phagocytosis assays

A polymer microarray of 120 polyurethanes was used to identify polymers that promoted the adhesion of bone marrow dendritic cells (BMDC). Identified polymers were coated onto glass cover slips and shown to be efficient substrates for the immobilisation of these primary cells, which underwent efficient phagocytosis while still presumably maintaining their immature state.

The properties of the positively charged loop region in PSI-G are essential for its "spontaneous" insertion into thylakoids and rapid assembly into the photosystem I complex

The PSI-G subunit of photosystem I (PSI) is an 11-kDa membrane protein that plays an important role in electron transport between plastocyanin and PSI and is involved in the stability of the PSI complex. Within the complex, the PSI-G subunit is bound to PSI-B and is in contact with Lhca1. PSI-G has two transmembrane spans connected by a positively charged stromal loop. The loop is inaccessible to proteases, indicating a tightly bound location within the PSI complex. Here, we have studied the insertion mechanism and assembly of PSI-G. We show that the protein inserts into thylakoids by a direct or "spontaneous" pathway that does not involve the activities of any known chloroplast protein-targeting machinery. Surprisingly, the positively charged stromal loop region plays a major role in this process. Mutagenesis or deletions within this region almost invariably lead to a marked lowering of insertion efficiency, strongly indicating a critical role for the loop in the organization of the transmembrane regions prior to or during membrane insertion. Finally, we have examined the assembly of newly inserted PSI-G into the PSI complex, since very little is known of the assembly pathway for this large multimeric complex. Interestingly, we find that inserted PSI-G can be found within the full PSI complex within the import assay time frame after insertion into thylakoids, strongly suggesting that PSI-G normally associates at the end of the assembly process. This is consistent with its location on the periphery of the complex.

Insertion of the plant photosystem I subunit G into the thylakoid membrane

Subunit G of photosystem I is a nuclear-encoded protein, predicted to form two transmembrane alpha-helices separated by a loop region. We use in vitro import assays to show that the positively charged loop domain faces the stroma, whilst the N- and C-termini most likely face the lumen. PSI-G constructs in which a His- or Strep-tag is placed at the C-terminus or in the loop region insert with the same topology as wild-type photosystem I subunit G (PSI-G). However, the presence of the tags in the loop make the membrane-inserted protein significantly more sensitive to trypsin, apparently by disrupting the interaction between the loop and the PSI core. Knock-out plants lacking PSI-G were transformed with constructs encoding the C-terminal and loop-tagged PSI-G proteins. Experiments on thylakoids from the transgenic lines show that the C-terminally tagged versions of PSI-G adopt the same topology as wild-type PSI-G, whereas the loop-tagged versions affect the sensitivity of the loop region to trypsin, thus confirming the in vitro observations. Furthermore, purification of PSI complexes from transgenic plants revealed that all the tagged versions of PSI-G are incorporated and retained in the PSI complex, although the C-terminally tagged variants of PSI-G were preferentially retained. This suggests that the loop region of PSI-G is important for proper integration into the PSI core. Our experiments demonstrate that it is possible to produce His- and Strep-tagged PSI in plants, and provide further evidence that the topology of membrane proteins is dictated by the distribution of positive charges, which resist translocation across membranes.

Alpha-glucan, water dikinase (GWD): a plastidic enzyme with redox-regulated and coordinated catalytic activity and binding affinity

The recently discovered potato tuber (Solanum tuberosum) alpha-glucan, water dikinase (GWD) (formerly known as R1) catalyzes the phosphorylation of starch by a dikinase-type reaction mechanism in which the beta-phosphate of ATP is transferred to either the C-6 or the C-3 position of the glucosyl residue of starch. In the present study, we found that the GWD enzyme is inactive in the oxidized form, which is accompanied by the formation of a specific intramolecular disulfide bond as determined by disulfide-linked peptide mapping. The regulatory properties of this disulfide linkage were confirmed by site-directed mutagenesis studies. Both reduced thioredoxin (Trx) f and Trx m from spinach leaves reduced and activated oxidized GWD at very low concentrations, with Trx f being the more efficient, yielding an S0.5 value of 0.4 microM. Interestingly, GWD displays a reversible and selective binding to starch granules depending on the illumination state of the plant. Here we show that starch granule-bound GWD isolated from dark-adapted plants exists in the inactive, oxidized form, which is capable of reactivation upon treatment with reduced Trx. Furthermore, the soluble form of GWD was found in its fully reduced state, providing evidence of a Trx-controlled regulation mechanism linking enzymatic activity and specific binding affinities of a protein to an intracellular surface. The regulatory site sequence, CFATC, of potato GWD is conserved in chloroplast-targeted GWDs from other species, suggesting an overall redox regulation of the GWD enzyme.

Arabidopsis VARIEGATED 3 encodes a chloroplast-targeted, zinc-finger protein required for chloroplast and palisade cell development

The stable, recessive Arabidopsis variegated 3 (var3) mutant exhibits a variegated phenotype due to somatic areas lacking or containing developmentally retarded chloroplasts and greatly reduced numbers of palisade cells. The VAR3 gene, isolated by transposon tagging, encodes the 85.9 kDa VAR3 protein containing novel repeats and zinc fingers described as protein interaction domains. VAR3 interacts specifically in yeast and in vitro with NCED4, a putative polyene chain or carotenoid dioxygenase, and both VAR3 and NCED4 accumulate in the chloroplast stroma. Metabolic profiling demonstrates that pigment profiles are qualitatively similar in wild type and var3, although var3 accumulates lower levels of chlorophylls and carotenoids. These results indicate that VAR3 is a part of a protein complex required for normal chloroplast and palisade cell development.

Identification of an Arabidopsis inorganic pyrophosphatase capable of being imported into chloroplasts

An Arabidopsis cDNA coding for a previously uncharacterized isoform of inorganic pyrophosphatase was isolated. It was used to complement an E. coli mutant, demonstrating that it coded for an active enzyme. MgCl(2) was necessary for the protein's activity, whilst NaF inhibited it. The K(m) for pyrophosphate and the pH optimum of the protein was determined. The gene coding for this protein was expressed in all tissues, and its expression in rosette leaves was induced by incubation on metabolizable sugars. In vitro import experiments demonstrated that the protein could be imported into chloroplasts and localized to the stromal compartment.

Uptake of a fluorescent dye as a swift and simple indicator of organelle intactness: import-competent chloroplasts from soil-grown Arabidopsis

We developed a rapid and reliable technique for specifically staining intact chloroplasts using the fluorescent dye carboxyfluorescein diacetate. Intact, import-competent chloroplasts were isolated simply and rapidly from soil-grown Arabidopsis thaliana plants, with yields of 20 +/- 5 micro g chlorophyll per g FW, greater than previously reported yields from soil-grown Arabidopsis. Traditional chloroplast isolation buffers sometimes contain low concentrations (<10 mM) sodium ascorbate as a general-purpose anti-oxidant, but we found that only Arabidopsis chloroplasts isolated in the presence of high concentrations (50-100 mM) of sodium ascorbate in the initial grinding buffer were import-competent.

Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans

Isoamylases are debranching enzymes that hydrolyze alpha-1,6 linkages in alpha-1,4/alpha-1,6-linked glucan polymers. In plants, they have been shown to be required for the normal synthesis of amylopectin, although the precise manner in which they influence starch synthesis is still debated. cDNA clones encoding three distinct isoamylase isoforms (Stisa1, Stisa2, and Stisa3) have been identified from potato. The expression patterns of the genes are consistent with the possibility that they all play roles in starch synthesis. Analysis of the predicted sequences of the proteins suggested that only Stisa1 and Stisa3 are likely to have hydrolytic activity and that there probably are differences in substrate specificity between these two isoforms. This was confirmed by the expression of each isoamylase in Escherichia coli and characterization of its activity. Partial purification of isoamylase activity from potato tubers showed that Stisa1 and Stisa2 are associated as a multimeric enzyme but that Stisa3 is not associated with this enzyme complex. Our data suggest that Stisa1 and Stisa2 act together to debranch soluble glucan during starch synthesis. The catalytic specificity of Stisa3 is distinct from that of the multimeric enzyme, indicating that it may play a different role in starch metabolism.

Three isoforms of isoamylase contribute different catalytic properties for the debranching of potato glucans

Isoamylases are debranching enzymes that hydrolyze alpha-1,6 linkages in alpha-1,4/alpha-1,6-linked glucan polymers. In plants, they have been shown to be required for the normal synthesis of amylopectin, although the precise manner in which they influence starch synthesis is still debated. cDNA clones encoding three distinct isoamylase isoforms (Stisa1, Stisa2, and Stisa3) have been identified from potato. The expression patterns of the genes are consistent with the possibility that they all play roles in starch synthesis. Analysis of the predicted sequences of the proteins suggested that only Stisa1 and Stisa3 are likely to have hydrolytic activity and that there probably are differences in substrate specificity between these two isoforms. This was confirmed by the expression of each isoamylase in Escherichia coli and characterization of its activity. Partial purification of isoamylase activity from potato tubers showed that Stisa1 and Stisa2 are associated as a multimeric enzyme but that Stisa3 is not associated with this enzyme complex. Our data suggest that Stisa1 and Stisa2 act together to debranch soluble glucan during starch synthesis. The catalytic specificity of Stisa3 is distinct from that of the multimeric enzyme, indicating that it may play a different role in starch metabolism.

PSI-O, a new 10-kDa subunit of eukaryotic photosystem I

A novel polypeptide with an apparent molecular mass of 9 kDa was detected after sodium dodecyl sulphate-polyacrylamide gel electrophoresis of Arabidopsis photosystem I (PSI) and was N-terminally sequenced. Corresponding cDNA clones encode a precursor protein of 140 amino acid residues which was imported into isolated intact chloroplasts and processed to the mature protein, designated PSI-O. The mature protein has two transmembrane helices and a calculated mass of 10104 Da. The PSI-O protein was also shown to be present in PSI isolated from barley and spinach, and was essentially absent in chloroplast grana. Expressed sequences encoding similar proteins are available from many species of plants and green algae.

Distinct Albino3-dependent and -independent pathways for thylakoid membrane protein insertion

The homologous proteins Oxa1, YidC, and Alb3 mediate the insertion of membrane proteins in mitochondria, bacteria, and chloroplast thylakoids, respectively. Depletion of YidC in Escherichia coli affects the integration of every membrane protein studied, and Alb3 has been shown previously to be required for the insertion of a signal recognition particle (SRP)-dependent protein, Lhcb1, in thylakoids. In this study we have analyzed the "global" role of Alb3 in the insertion of thylakoid membrane proteins. We show that insertion of two chlorophyll-binding proteins, Lhcb4.1 and Lhcb5, is almost totally blocked by preincubation of thylakoids with anti-Alb3 antibodies, indicating a requirement for Alb3 in the insertion pathway. Insertion of the related PsbS protein, on the other hand, is unaffected by Alb3 antibodies, and insertion of a group of SRP-independent, signal peptide-bearing proteins, PsbX, PsbW, and PsbY, is likewise completely unaffected. Proteinase K is furthermore able to completely degrade Alb3, but this treatment does not affect the insertion of these proteins. Among the thylakoid proteins studied here, Alb3 requirement correlates strictly with a requirement for stromal factors and nucleoside triphosphates. However, the majority of proteins tested do not require Alb3 or any other known form of translocation apparatus.

Insertion of PsaK into the thylakoid membrane in a "Horseshoe" conformation occurs in the absence of signal recognition particle, nucleoside triphosphates, or functional albino3

The photosystem I subunit PsaK spans the thylakoid membrane twice, with the N and C termini both located in the lumen. The insertion mechanism of a thylakoid membrane protein adopting this type of topology has not been studied before, and we have used in vitro assays to determine the requirements for PsaK insertion into thylakoids. PsaK inserts with high efficiency and we show that one transmembrane span (the C-terminal region) can insert independently of the other, indicating that a "hairpin"-type mechanism is not essential. Insertion of PsaK does not require stromal extract, indicating that signal recognition particle (SRP) is not involved. Removal of nucleoside triphosphates inhibits insertion only slightly, both in the presence and absence of stroma, suggesting a mild stimulatory effect of a factor in the translation system and again ruling out an involvement of SRP or its partner protein, FtsY. We, furthermore, find no evidence for the involvement of known membrane-bound translocation apparatus; proteolysis of thylakoids destroys the Sec and Tat translocons but does not block PsaK insertion, and antibodies against the Oxa1/YidC homolog, Alb3, block the SRP-dependent insertion of Lhcb1 but again have no effect on PsaK insertion. Because YidC is required for the efficient insertion of every membrane protein tested in Escherichia coli (whether SRP-dependent or -independent), PsaK is the first protein identified as being independent of YidC/Alb3-type factors in either thylakoids or bacteria. The data raise the possibility of a wholly spontaneous insertion pathway.

Functional Characterization of Recombinant Chloroplast Signal Recognition Particle

The signal recognition particle (SRP) is a ubiquitous system for the targeting of membrane and secreted proteins. The chloroplast SRP (cpSRP) is unique among SRPs in that it possesses no RNA and is functional in post-translational as well as co-translational targeting. We have expressed and purified the two components of the Arabidopsis thaliana chloroplast signal recognition particle (cpSRP) involved in post-translational transport: cpSRP54 and the chloroplast-specific protein, cpSRP43. Recombinant cpSRP supports the efficient in vitro insertion of pea preLhcb1 into isolated thylakoid membranes. Recombinant cpSRP is a stable heterodimer with a molecular mass of approximately 100 kDa as determined by analytical ultracentrifugation, gel filtration analysis, and dynamic light scattering. The interactions of the components of the recombinant heterodimer and pea preLhcb1 were probed using an immobilized peptide library (pepscan) approach. These data confirm two previously reported interactions with the L18 region and the third transmembrane helix of Lhcb1 and suggest that the interface of the cpSRP43 and cpSRP54 proteins is involved in substrate binding. Additionally, cpSRP components are shown to recognize peptides from the cleavable, N-terminal chloroplast transit peptide of preLhcb1. The interaction of cpSRP43 with cpSRP54 was probed in a similar experiment with a peptide library representing cpSPR54. The C terminus of cpSRP54 is essential for the formation of the stable cpSRP complex and cpSPR43 interacts with distinct regions of the M domain of cpSRP54.

Conformation of a purified "spontaneously" inserting thylakoid membrane protein precursor in aqueous solvent and detergent micelles

Subunit W of photosystem II (PsbW) is a single-span thylakoid membrane protein that is synthesized with a cleavable hydrophobic signal peptide and integrated into the thylakoid membrane by an apparently spontaneous mechanism. In this study, we have analyzed the secondary structure of the pre-protein at early stages of the insertion pathway, using purified recombinant pre-PsbW. We show that the protein remains soluble in Tris buffer after removal of detergent. Under these conditions pre-PsbW contains no detectable alpha-helix, whereas substantial alpha-helical structure is present in SDS micelles. In aqueous buffer, the tryptophan fluorescence emission characteristics are intermediate between those of solvent-exposed and hydrophobic environments, suggesting the formation of a partially folded structure. If denaturants are excluded from the purification protocol, pre-PsbW purifies instead as a 180-kDa oligomer with substantial alpha-helical structure. Mature-size PsbW was prepared by removal of the presequence, and we show that this protein also contains alpha-helix in detergent but in lower quantities than the pre-protein. We therefore propose that pre-PsbW contains alpha-helical structure in both the mature protein and the signal peptide in nonpolar environments. We propose that pre-PsbW acquires its alpha-helical structure only during the later, membrane-bound stages of the insertion pathway, after which it forms a "helical hairpin"-type loop intermediate in the thylakoid membrane.

Compliance with guidelines for continuity of care in therapeutics from hospital to community

OBJECTIVES

To evaluate compliance with the Australian Pharmaceutical Advisory Council's National guidelines to achieve the continuum of quality use of medicines between hospital and community.

DESIGN

Descriptive survey, based on questionnaires filled out by general practitioners, of a sample of patients following recent discharge from public hospitals, collated with hospital record reviews for a 20% subsample of the patients.

PARTICIPANTS AND SETTING

357 GPs practising within the postcode boundaries of the South East Sydney Area Health Service were randomly selected to take part in the survey. Of 219 GPs who agreed to participate, 106 completed questionnaires on 203 patients. For a subsample of 38 patients, hospital records were reviewed and compared with the GP survey data.

RESULTS

For 52% (105/203) of all patients the GP was not notified of hospital admission. Medication management was documented in the discharge plan for 13% (5/38) of the subsample. Communication in both directions between GP and hospital about medications was recorded for 13% (5/38) of the subsample. Consultation with the GP about the patient's medication during the hospital stay occurred for 11% (22/203) of all patients and 24% (9/38) of the subsample. Ninety-one per cent of patients (185/203) were discharged with sufficient medication to last until they saw their GP. Fewer than 10% of patients received all the information the Guidelines require. For 33% (66/203) of the patients, GPs considered there was at least one barrier (eg, language, cultural) to understanding the medication regimen.

CONCLUSIONS

Compliance with the Guidelines is not good at present. Their acceptance may be strengthened by formulating specific target indicators. A minimum indicator would be notifying the GP of three out of four matters: the patient's admission; medications on discharge; medication changes; and follow-up arrangements.

Co-prescribing of SSRIs and TCAs in Australia: how often does it occur and who is doing it?

AIMS

To determine the frequency with which the selective serotonin re-uptake inhibitor (SSRI) antidepressants are used as add-on therapy to the tricyclic antidepressants (TCA) rather than as replacement therapy.

METHODS

The data analysed were profiles of prescription records by date of supply to the patient. From within the national administrative dispensing claims database, the subset eligible for social security entitlements was identified as individuals by means of their coded permanent identification numbers (PINs). Following the initial supply of an SSRI in January 1996, the subsequent 6 months dispensing of SSRI and TCA antidepressants to these individuals was examined. The main outcome measure was the proportion of individuals to whom SSRIs and TCAs were dispensed concurrently, as an indirect measure of coprescription. In instances where a patient was receiving prescriptions for SSRIs and TCAs that had been written by the one doctor only, the major specialty of the doctor was investigated.

RESULTS

55 271 PINs were dispensed 63 865 SSRI prescriptions in January 1996 which represented over half (52%) of the total community SSRI prescriptions dispensed in that month. The number of these patients meeting the criteria for coprescription of SSRIs and TCAs over the next 6 months was 2773 (5%). The coprescribing instances were highest in Queensland and the prescribers most frequently involved had psychiatry major specialty codes.

CONCLUSIONS

Among SSRI users there is a cohort of patients who, within the same time frame, are receiving supplies of a TCA, the nonselective drug that the SSRIs were designed to replace. This is indirect evidence of probable coprescription. Such combination use is of uncertain clinical and cost effectiveness, and carries additional risks. The SSRIs were included on the subsidy list in Australia on the basis of reasonable cost effectiveness as monotherapy compared with the TCAs. Our data imply that for some patients, antidepressant prescribing is inconsistent with the basis on which government subsidy was approved.

Asthma as a consumer issue

Australian Family Physician is proud to provide this clinical audit activity. This is based on material drawn from Dr Andrea Mant's book Thinking about Prescribing: A Handbook for the Quality Use of Medicines. General practice prescribing is an area of intense interest to the profession, the community and the government. It is also an extremely dynamic area with frequent changes in recommended treatment regimens. This activity is designed to encourage each practitioner to focus on individual prescribing habits and to reflect on these in the light of new developments and recommendations.

Recent trends in the use of antidepressant drugs in Australia, 1990-1998

OBJECTIVE

To determine the pattern of use of antidepressant drugs in the Australian community, 1990-1998, and to compare this with those of other developed countries.

DESIGN

Retrospective analyses of prescription and sales data, together with information about patient encounters for depression (from an ongoing survey of service provision by general practitioners) and population-based prevalence estimates for affective disorders (from community health surveys).

MAIN OUTCOME MEASURES

National and international consumption of antidepressants, expressed in defined daily doses (DDDs) per 1000 population per day. Changes in both the frequency of general practice patient encounters for depression and population-based prevalence estimates for affective disorders.

RESULTS

Dispensing of antidepressant prescriptions through community pharmacies in Australia increased from an estimated 12.4 DDDs/1000 population per day in 1990 (5.1 million prescriptions) to 35.7 DDDs/1000 population/day in 1998 (8.2 million prescriptions). There has been a rapid market uptake of the selective serotonin reuptake inhibitors (SSRIs), accompanied by a decrease of only 25% in the use of tricyclic antidepressants (TCAs). In 1998, the level of antidepressant use in Australia was similar to that of the United States, while the rate of increase in use between 1993 and 1998 was second only to that of Sweden. In Australia, depression has risen from the tenth most common problem managed in general practice in 1990-91 to the fourth in 1998-99, and the number of people reporting depression in the National Health Surveys (1995 v 1989-90) has almost doubled. Of the prescriptions dispensed in 1998 for antidepressant drugs subsidised by the Pharmaceutical Benefits Scheme, 85% were written by general practitioners, and 11.2% by psychiatrists.

CONCLUSIONS

As in most developed countries, antidepressant use increased between 1990 and 1998. The rapid market uptake of the new antidepressants, particularly SSRIs, is likely to have been driven by increased awareness of depression, together with availability and promotion of new therapies.

Incorporating evidence based medicine (EBM) into general practice

BACKGROUND

The increased application of evidence based medicine (EBM) to health care practice has been endorsed in national health policy. This paper focuses on what EBM means for GPs.

OBJECTIVES

To present the outcomes of engaging practising GPs in applying EBM principles to a general practice scenario.

DISCUSSION

Caution about the potential for misuse of EBM has been voiced by GPs based on the biopsychosocial model of general practice and concerns about the limited utility of largely biomedical evidence in general practice. The EBM process begins with converting information needs into questions, but this first step presupposes that the doctor has obtained a good history including eliciting any hidden agenda. It is important to recognise the context in which people's health issues and problems arise, the paucity of evidence that is derived within the biopsychosocial model of general practice, and the difficulties that GPs face in accessing evidence.

Examining the adequacy of quantities available for subsidized antidepressant prescriptions in Australia

In Australia the Pharmaceutical Benefits Scheme (PBS), a national drug insurance plan, aims to provide around a month's therapy for medication used in chronic conditions. However, there are marked differences among the most commonly used antidepressants in the number of days supply represented by the PBS maximum quantity after adjustment for the defined daily dose (DDD). The DDD is the assumed adult daily dose for a drug and is a WHO drug utilization standard. Whereas the selective serotonin re-uptake inhibitors (SSRIs) and moclobemide largely provide around a month's supply at the DDD, most tricyclic antidepressant (TCA) items provide considerably less than this .A patient tracking study was conducted to determine the average length of time between prescription re-supplies for a number of tricyclic antidepressants and newer antidepressants as a means of measuring the efficiency of PBS supply for the different classes of antidepressant. The number of days between dispensings was similar for patients no matter whether they were taking TCAs, SSRIs or moclobemide, although for the older antidepressants presumably at a much lower prescribed daily dose than the DDD. Care needs to be taken when adjusting usage with the DDD/1000/day unit of measurement in cases where the DDD does not reflect the prescribed daily dose (PDD).