Practice patterns in management of differentiated thyroid cancer since the 2014 British Thyroid Association (BTA) guidelines

BACKGROUND

The updated 2014 BTA guidelines emphasised a more conservative, risk adapted model for the management of low-risk differentiated thyroid cancer (DTC). In comparison to historical approach of total thyroidectomy combined with radioactive iodine, treatment de-escalation is increasingly supported.

AIMS

To evaluate the impact of the updated BTA guidelines on the management of DTC cases at regional UK centre.

METHODS

All DTC patients were retrospectively identified from regional thyroid MDT database between Jan2009-Dec2020. Oncological treatment and clinico-pathological characteristics were analysed.

RESULTS

623 DTC cases were identified; 312 (247 female: 65 male) between 2009 and 2014 and 311 (225 female: 86 male) between 2015 and 2020. Median age is 48 years (range 16-85). By comparing pre- and post-2015 cohorts, there was a significant drop in total thyroidectomy (87.1% vs 76.8%, p = 0.001) and the use of radioactive iodine (RAI) (73.1% vs 62.1%, p = 0.003) in our post-2015 cohort. When histological adverse features were analysed, extra-thyroidal extension (4.2% vs 17.0%, p=< 0.001), lymphovascular invasion (31.4% vs 50.5%, p=<0.001) and multi-centricity (26.9% vs 43.4%, p = 0.001) were significantly increased in the post 2015 cohort. Nonetheless, total thyroidectomy (TT) remains the treatment choice for low risk T1/2 N0 M0 disease in 65.3% (124/190) in post-2015 cohort for several reasons. Reasons include adverse histological features (50.8%), benign indications (32.5%), contralateral nodules (11.7%), patient preference (2.5%), and diagnostic uncertainty (2.5%).

CONCLUSION

Our study confirms a move towards a more conservative approach to patients with low-risk DTC in the UK, which is in keeping with the BTA 2014 guideline and international trends, but total thyroidectomy remains prevalent for low risk T1/2 N0 M0 disease for other reasons.

Alkyl Hydrogen Phosphonate Derivatives of the anti-HIV Agent AZT may be Less Toxic than the Parent Nucleoside Analogue

Novel alkyl hydrogen phosphonate derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridite chemistry. These materials are designed to act as labile membrane-soluble prodrugs of the bioactive free nucleotides. In vitro evaluation has revealed the compounds to have a pronounced and selective antiviral action. Short-chain (C1-C7) alkyl derivatives are more potent than the parent hydrogen phosphonate, whilst one long-chain (C18) compound is less active. In an assay that demonstrates the toxicity of the parent drug AZT, the alkyl H-phosphonates appear to be less cytotoxic, whilst retaining full antiviral activity. Lastly, the compounds are all poorly active in a cell line (JM) that is poorly responsive to AZT, indicating that they act as depot forms of the nucleoside rather than of the free nucleotide.

Inhibitory Effects of Novel Mannose-Binding Lectins on HIV-Infectivity and Syncytium Formation

Several new lectins were isolated and characterized with respect to their composition and sugar binding specificities and their ability to prevent HIV-1 infection. Twelve of the 13 mannose-specific lectins were inhibitory to varying degrees. The most effective were Machaerium biovulatum agglutinin (MBA) and M. lunatus agglutinin (MLA) which at 0.4 μg ml−1 prevented the cytopathic effect of the virus. Lower protection was obtained with Bowringia mildbraedii agglutinin (BMA), Galanthus nivalis agglutinin (GNA), Lablab niger agglutinin (LNA) and Dolichos lablab agglutinin (DLA). All these lectins are more protective than Con A while MBA is nearly 10 times more potent than any previously reported lectin. In each case the selective antiviral activity appears to be due to interaction with virus and not with some component on the target cell. MBA and GNA immobilized on Sepharose specifically bound gp120.

Studies of binding to glycoproteins confirmed the recognition of particular isomers of high mannose oligosaccharides Man9 to Man7GlcNAc2 by BMA and of Man5GlcNAc2 glycopeptides by GNA. By contrast, MBA did not bind oligomannosidic structures but did interact with ovalbumin, a glycoprotein rich in hybrid-type glycans.

Synthesis and Evaluation of Some Symmetrical Phosphate Dimer Derivatives of 3′-Modified Nucleosides as Potential anti-HIV Agents

Novel symmetrical nucIeotide-(5′,5′)-dimers of 3′-O-acetylthymidine, 3′-O-methylthymidine, 3′-O-ethylthymidine, 3′-O-n-propylthymidine and 3′-azido-3′-deoxythymidine (AZT) were synthesized as membrane soluble pro-drugs. These were prepared using phosphorodichloridate chemistry and were characterised by spectroscopic and analytical data. In-vitro evaluation of the derivatives in cells acutely infected with the human immunodeficiency virus (HIV-1) demonstrated a range of activities. These derivatives were generally found to display poor inhibition of HIV proliferation. Derivatives containing AZT moieties were found to be potent, but such compounds were less active than the parent nucleoside. The data indicated that the AZT-containing compounds act primarily via the release of the free nucleoside. However, in some cases, the dimers of certain inactive nucleoside analogues were found to be active. In these cases, release of the nucleoside alone cannot account for the activity.

Inhibition of HIV Infection by Caffeoylquinic Acid Derivatives

The caffeoylquinic acids 3,4,5-tri-O-caffeoylquinic acid (1) and 4,5-di-O-caffeoylquinic acid (2), as well as caffeic acid (4) and synapoic acid (5) were isolated from the plant Securidaka longipedunculata (polygalaceae). 1 exhibited a greater selective inhibition of HIV replication than 2 which had an anti-HIV activity similar to that of 3,4,5-tri-O-galloylquinic acid (3), isolated from Guiera senegalensis (combretaceae); 4 and 5 were ineffective and the structurally related compound rosmarinic acid (6) had only slight anti-HIV activity. Studies of the actions of these compounds suggest that inhibition of the viral reverse transcriptase in vitro is non-specific and that they act by specific binding to gp120 which prevents its interaction with CD4 on T-lymphocytes and thus inactivates virus infectivity.

The Enzymatic Synthesis and Anti-HIV Activity of 9-β-D-2-Deoxy and 9-β-D-2′,3′-Dideoxynucleossdes of 2-Aminopurine

The 9-β-D-2′-deoxy and 9-β-D-2′,3′-dideoxyribonucleosides of 2-aminopurine have been prepared using crude nucleoside N-deoxyribosyltransferases (E.C. 2.4.2.6) from Lactobacillus leichmannii in the presence of 10% ethylene glycol to inhibit degradation of the product nucleosides. The 2′,3′-dideoxynucleoside of 2-aminopurine is an inhibitor of the replication of HIV-1, HIV-2, and SIV with EC50 values in the range 8–100 μM depending on the cell line used and has low in vitro toxicity at its effective concentrations.

In Sickness and in Health: The Relationships Between Bacteria and Bile in the Human Gut

Colonization of a human host with a commensal microbiota has a complex interaction in which bacterial communities provide numerous health benefits to the host. An equilibrium between host and microbiota is kept in check with the help of biliary secretions by the host. Bile, composed primarily of bile salts, promotes digestion. It also provides a barrier between host and bacteria. After bile salts are synthesized in the liver, they are stored in the gallbladder to be released after food intake. The set of host-secreted bile salts is modified by the resident bacteria. Because bile salts are toxic to bacteria, an equilibrium of modified bile salts is reached that allows commensal bacteria to survive, yet rebuffs invading pathogens. In addition to direct toxic effects on cells, bile salts maintain homeostasis as signaling molecules, tuning the immune system. To cause disease, gram-negative pathogenic bacteria have shared strategies to survive this harsh environment. Through exclusion of bile, efflux of bile, and repair of bile-induced damage, these pathogens can successfully disrupt and outcompete the microbiota to activate virulence factors.

A cost-effective protocol for screening patients for methicillin-resistant Staphylococcus aureus

The incidence of hospital-acquired infection with methicillin-resistant Staphylococcus aureus (MRSA) is rising worldwide. Rapid identification of MRSA carriers is an important step in reducing the risk of transmission to other patients. Molecular methods are increasingly popular but are technically demanding and expensive. This study assesses the modification of one of the commercially available latex agglutination tests (Mastalex-MRSA) for the identification of penicillin-binding protein 2' on known strains of MRSA as well as other organisms identified from chromogenic agar plates. A total of 3050 patients with unknown MRSA status were processed through the routine laboratory during the investigation period and 73 of these were presumptive positive following overnight incubation. Of 70 patients who could be evaluated, 32 (43.8%) specimens would be suitable for use with the kit directly from overnight incubation on chromogenic agar, and the other 38 (52.1%) would be suitable following four hours' incubation on blood agar. The cost of one positive MRSA test with the inclusion of this test is Euro 15.15 compared with published reports of Euro 35.00 for a commercial polymerase chain reaction (PCR) test. This protocol would allow the reporting of presumptive positive MRSA results approximately 24 hours earlier than currently achieved.

Inhibition of glycosidases by aldonolactones of corresponding configuration: Preparation of (1-->5)-lactones by catalytic oxidation of pyranoses and study of their inhibitory properties

1. A method was devised for the preparation of (1-->5)-lactones from pyranose sugars and uronic acids by platinum-catalysed oxidation with gaseous oxygen in aqueous solution at acid pH. It was applied to mannose, N-acetylglucosamine, N-acetylgalactosamine, glucuronic acid, galacturonic acid, galactose, l-arabinose and d-fucose. 2. Only the first three yielded products that could be obtained in the solid state without decomposition. In every case, however, the oxidation product in aqueous solution behaved as the aldono-(1-->5)-lactone, and was more inhibitory towards the appropriate glycosidases than any aldonolactone preparation hitherto examined. 3. The stabilities of the oxidation products were studied, and their interconversion with the (1-->4)-lactones was demonstrated. Ring-opening does not appear to be mandatory for this isomeric change, which in some instances is very rapid. 4. To explain all the inhibitory effects observed with aldonolactones on glycosidases of corresponding configuration, it is tentatively postulated that inhibition may be due entirely to the (1-->5)-lactone, and that any inhibitory effect seen with the (1-->4)-lactone is a measure of the extent and speed of its conversion into the (1-->5)-lactone in aqueous solution.

Emergence of resistance to oseltamivir among influenza A(H1N1) viruses in Europe

Binary file ES_Abstracts_Final_ECDC.txt matches

Testing by Sysmex UF-100 flow cytometer and with bacterial culture in a diagnostic laboratory: a comparison

A large proportion of the samples tested in routine diagnostic microbiology laboratory are urine samples. The gold standard is bacterial culture, but a high proportion of samples cultured are negative. Unnecessary testing can be reduced and an improved service provided by an effective screening test. The Sysmex UF-100 flow cytometer has been developed to count cells and casts accurately in urine samples. Its performance in a screening test was compared with bacterial culture by using 1005 consecutive urine samples, and cut-off criteria were established. Cut-off values of 3000 bacteria/microl and 111 WBC/microl provided the best discrimination. Of 1005 samples, 606 (60%) would be cultured. Sixteen samples that were not selected according to these criteria were culture positive. This was considered acceptable for our routine use. The use of a testing algorithm incorporating the Sysmex UF-100 flow cytometer has improved the quality and efficiency of urine testing within the routine microbiology laboratory.

Differences in conductance of M2 proton channels of two influenza viruses at low and high pH

The M2 protein of influenza A viruses forms a proton channel involved in modifying virion and trans Golgi pH during infection. Previous studies of the proton current using whole-cell patch clamp of mouse erythroleukaemia (MEL) cells expressing the M2 protein of the "Weybridge" strain provided evidence for two protonation sites, one involved in permeation, the other in activation by acid pH. The present report compares the M2 channels of two different strains of influenza virus, "Weybridge" (WM2) and "Rostock" (RM2). Whereas with external acid pH the current-voltage relations showed similar small degrees of inward rectification, a similar apparent K(d) of approximately 10 microM for proton permeation and a high selectivity for protons over Na(+), the two M2 proteins differed in whole-cell conductance at low and high pH. The proton conductance of unit membrane area was on average 7-fold greater in RM2- than WM2-expressing MEL cells. At high external pH WM2 was shown previously to have small conductance for outward current at positive driving potential. In contrast, RM2 shows high conductance for outward current with high external pH, but shows small conductance for inward current with high internal pH, conditions in which WM2 shows high conductance for inward current. The different properties of the conductances due to the two channels at high pH were determined by three amino acids in their transmembrane domains. All intermediate mutants possessed one or other property and transformation of the WM2 phenotype into that of RM2 required substitution in all three residues V27I, F38L and D44N; single substitutions in RM2 effected the opposite phenotypic change. The significance of this difference for virus replication is not clear and it may be that the higher proton flux associated with RM2 is the main factor determining its increased ability to dissipate pH gradients. It is apparent, however, from the specific differences in the sidedness of the pH-induced changes in voltage dependence of the whole-cell current that this is an intrinsic property of the virus proton channel which may have parallels with regulation of other proton channels.

The evolution of human influenza viruses

The evolution of influenza viruses results in (i) recurrent annual epidemics of disease that are caused by progressive antigenic drift of influenza A and B viruses due to the mutability of the RNA genome and (ii) infrequent but severe pandemics caused by the emergence of novel influenza A subtypes to which the population has little immunity. The latter characteristic is a consequence of the wide antigenic diversity and peculiar host range of influenza A viruses and the ability of their segmented RNA genomes to undergo frequent genetic reassortment (recombination) during mixed infections. Contrasting features of the evolution of recently circulating influenza AH1N1, AH3N2 and B viruses include the rapid drift of AH3N2 viruses as a single lineage, the slow replacement of successive antigenic variants of AH1N1 viruses and the co-circulation over some 25 years of antigenically and genetically distinct lineages of influenza B viruses. Constant monitoring of changes in the circulating viruses is important for maintaining the efficacy of influenza vaccines in combating disease.

Antigenic and genomic relation between human influenza A (H3N2) viruses circulating in Argentina during 1998 and the H3N2 vaccine component

OBJECTIVE

Due to the lack of correlation from 1994 to 1997 between the A H3N2 component of the influenza vaccine recommended for this period and the circulating viruses in Argentina, we decided to study the antigenic and genomic relationships of the 1998 A H3N2 Argentine circulating strains with the corresponding vaccine component for that year as recommended by the World Health Organization (WHO).

METHODS

We selected 18 influenza A H3N2 strains isolated in Argentina during 1998 to carry out an antigenic and genomic study of their hemagglutinin (HA) and neuraminidase (NA) proteins. For the genomic study we added 3 isolates from Uruguay. We compared the Argentine and Uruguayan strains with available reference strains.

RESULTS

We found that all 18 strains from Argentina were similar to the A/Sydney/5/97 (H3N2) strain, as opposed to the A/Wuhan/359/95 (H3N2) strain, which was the vaccine component. This result was confirmed by the genomic study.

CONCLUSIONS

The approach that we applied in Argentina has improved the quality and quantity of information about influenza in the country. This type of work should be encouraged in other countries in order to help choose the most appropriate vaccine components each year and provide individuals with the best possible protection against influenza.

H9N2 subtype influenza A viruses in poultry in pakistan are closely related to the H9N2 viruses responsible for human infection in Hong Kong

Following the outbreak of H5N1 "bird flu" in Hong Kong in 1997, the isolation of H9N2 subtype viruses from patients in southern China and Hong Kong SAR once again raised the spectre of a possible influenza pandemic. H9N2 viruses have recently been responsible for disease in poultry in various parts of the world and preliminary studies of the H9 haemagglutinin (HA) genes of viruses isolated during 1998 and 1999 in Germany, Iran, Pakistan, and Saudi Arabia showed a close relationship to the HA genes of the viruses that infected two children in Hong Kong SAR. Analysis of the complete genome of a Pakistan isolate, A/chicken/Pakistan/2/99, showed that it is closely related in all eight genes (97-99% homology) to the human H9N2 isolates and furthermore that the six genes encoding internal components of the virus are similar to the corresponding genes of the H5N1 viruses that caused 6 (out of 18) fatal cases of human infection. Thus H9N2 viruses similar to those that caused human infections in Hong Kong are circulating more widely in other parts of the world. Whether or not these H9N2 viruses also have features that facilitate avian-to-human transmission is not known. Since avian H9N2 viruses are currently perceived to represent a significant threat to human health it is important to determine whether or not viruses of this subtype circulating in poultry in various parts of the world have the potential to infect people.

In vitro anti-influenza virus activity of a plant preparation from Geranium sanguineum L

A polyphenolic complex (PC), isolated from the Bulgarian medicinal plant Geranium sanguineum L., was shown to have selective anti-influenza activity in vitro. Expression of HA on the surface of cells infected with A/chicken/Rostock/34, virus-induced cytopathic effect, infectious virus yield and plaque formation were all reduced at non-toxic concentrations of PC. Synthesis of virus proteins was also selectively inhibited. High concentrations of PC (> 200 microg/ml) exhibited a strong virucidal effect. Although the action was directed against an early stage of infection (within 3 h of infection), the process directly affected was not identified. The selectivity of antiviral action was confirmed by the variation in sensitivity of different influenza viruses to PC and the selection of variants with reduced drug sensitivity.

The anti-HIV activity and mechanisms of action of pure compounds isolated from Rosa damascena

Water and methanol extracts of Rosa damascena exhibited moderate anti-HIV activity. The anti-viral activities of 9 compounds isolated from the methanol extract were compared. The tetrahydroxyflavanone (kaempferol, 1), was effective in reducing the maturation of infectious progeny virus apparently due to selective inhibition of the viral protease. On the other hand the pentahydroxyflavone (quercetin, 2) and two 3-substituted derivatives of kaempferol appeared to inhibit HIV-infection by preventing binding of gp120 to CD4. 2-Phenylethanol-O-(6-O-galloyl)-beta-D-glucopyranoside 8 interacted irreversibly with gp120 and neutralized virus infectivity. The differences in the modes of action of 1 and 8 can account for the apparent synergy of their anti-viral activities.

The NB protein is an integral component of the membrane of influenza B virus

The results of biochemical and immunoelectron microscopic studies provide evidence that the NB protein is an integral component of the influenza B virion. Its glycosylation and orientation in the membrane were shown to be equivalent to that of NB in the plasma membrane of virus-infected cells. Sensitivity to proteinase K showed that the N terminus is exterior to the virion and gold immunolabelling of freeze-fractured replicas showed that the C terminus is located in the interior of the virion. The similarities between NB of influenza B and M2 of influenza A viruses in structural features, their presence in the virion and possession of an ion channel activity suggest that, by analogy with the M2 protein, NB may also have a role in virus entry.

Selective proton permeability and pH regulation of the influenza virus M2 channel expressed in mouse erythroleukaemia cells

1. The M2 protein of influenza A virus is implicated in transmembrane pH regulation during infection. Whole-cell patch clamp of mouse erythroleukaemia cells expressing the M2 protein in the surface membrane showed a conductance due to M2 which was specifically blocked by the anti-influenza drug rimantadine. 2. The ion selectivity of the rimantadine-sensitive current through M2 was determined. Reversal potentials were close to equilibrium potentials for transmembrane pH gradients and not to those for Na+, K+ or Cl- concentration gradients. M2 permeability to Na+ relative to H+ was estimated to be less than 6 x 10(-7). 3. The M2 conductance increased as external pH decreased below 8.5 and approached saturation at an external pH of 4, effects attributable to increased permeability due to increased driving potential and to activation by low external pH. Both activation and permeation could be described by interaction of protons with sites on M2, with apparent dissociation constants of approximately 0.1 microM and 1 microM, respectively, under physiological conditions. 4. The M2 protein can transfer protons selectively across membranes with the H+ electrochemical gradient, properties consistent with its role in modifying virion and trans-Golgi pH during virus infection.

D-xylan-degrading enzyme system from the fungus Phanerochaete chrysosporium: isolation and partial characterisation of an alpha-(4-O-methyl)-D-glucuronidase

A number of fungi were screened for their capacities to produce extracellular alpha-(4-O-methyl)-D-glucuronidase. Of those tested, Phanerochaete chrysosporium ATCC 24725 produced the enzyme in greatest yield. The single alpha-(4-O-methyl)-D-glucuronidase produced by this fungus was purified by a series of chromatographic methods involving anion exchange, hydrophobic interaction and chromatofocusing. Isolated in this way, the enzyme had an apparent molecular mass of 112 kDa in sodium dodecyl sulphate polyacrylamide gels, and a pI of 4.6 when determined by isoelectric focusing in polyacrylamide gels. The enzyme was optimally active at pH 3.5, but showed significant activity over the pH range 3-5. In the absence of substrate the enzyme was inactivated at pH 3.5 in 2 h at 50 degree C: at pH 5.0 it retained 42% of its activity for 24 h at this temperature. The enzyme showed little activity on glucuronoxylan polysaccharides, but some short-chain xylo-oligosaccharides which were substituted with alpha-linked 4-O-methyl-D-glucopyranosyl uronic acid attached to the 2-position of the non-reducing D-xylopyranosyl residue were readily hydrolysed. There were marked synergistic effects apparent in the release of 4-O-methyl-D-glucopyranosyl uronic acid from various glucuronoxylans when the alpha-(4-O-methyl)-D-glucuronidase was acting in concert with endo-(1-->4)-beta-D-xylanase, and with beta-D-xylosidase and/or an alpha-L-arabinofuranosidase.

Anti-(human immunodeficiency virus) activity of polyoxotungstates and their inhibition of human immunodeficiency virus reverse transcriptase

Heteropolyoxotungstates of the Keggin class containing different heteroatoms were tested for inhibition of two strains of human immunodeficiency virus 1 (HIV-1); they exhibited varying antiviral activity. Compounds containing boron were inactive, only one of those containing phosphorus showed selective anti-viral activity, whereas all silicon-containing compounds exhibited significant anti-viral activity in C8166 cells infected with the IIIB strain. Their effectiveness was some 10-fold higher in JM cells with selectivity indices of about 2000. The silicotungstates were effective inhibitors of HIV reverse transcriptase, showing greater inhibition with RNA/DNA template primers than with DNA/DNA template.primer. Kinetic analysis demonstrated that they inhibit the enzyme by different mechanisms, as, of the four compounds examined, two competed with template.primer and two competed with deoxynucleoside triphosphate. Inhibition of DNA polymerase activity by these compounds was compared using polymerases from different sources, including human; although not necessarily most specific for HIV-1 reverse transcriptase, they did not inhibit all DNA polymerases to a similar degree.

Functional reconstitution in lipid vesicles of influenza virus M2 protein expressed by baculovirus: evidence for proton transfer activity

The influenza virus M2 protein was expressed from a recombinant baculovirus in Spodoptera frugiperda Sf9 cells, purified and reconstituted into artificial membrane vesicles. The specific inhibitor amantadine overcame the toxic activity of the protein and boosted the rate of M2 synthesis by a factor of 10, allowing yields of about 1 mg of purified M2 protein per g of Sf9 cells. M2 protein expressed in this system was phosphorylated and palmitoylated and displayed properties similar to the authentic virus protein. Purified wild-type M2 protein and an amantadine-resistant mutant M2 (M2 delta) with a deletion in the trans-membrane domain (amino acids 28 to 31) were incorporated into lipid vesicles, which were loaded with the fluorescent pH indicator pyranine. On imposition of an ionic gradient, M2 caused a decrease in intravesicular pH, which was susceptible to inhibition by 0.1 to 1 microM-rimantadine or N-ethyl-rimantadine. M2 delta behaved similarly but exhibited the expected drug resistance. These experiments indicate that isolated M2 functions as an ion channel and demonstrates in vitro M2-mediated proton translocation.

Certain phosphoramidate derivatives of dideoxy uridine (ddU) are active against HIV and successfully by-pass thymidine kinase

As part of our effort to deliver masked phosphates inside living cells we have discovered that certain phosphate triester derivatives of the inactive nucleoside analogue, dideoxy uridine (ddU) are inhibitors of HIV replication at microM levels. Moreover, we note that certain phosphoramidate derivatives retain their activity in thymidine kinase-deficient cells, which indicates that they do indeed act by intracellular release of the free nucleotide, and that they successfully by-pass the nucleoside kinase. The increased structural freedom in drug design which this allows may have implications for dealing with the emergence of resistance and may stimulate the discovery of improved therapeutic agents.

Antigenic and genetic characterization of current influenza strains

Annually the influenza centre receives more than 1000 virus isolates from around the world to monitor the changing pattern of viruses causing influenza throughout the year. These are characterized antigenically using both polyclonal and monoclonal antibodies and selected viruses are subjected to closer scrutiny by nucleotide sequence analyses of their HA genes. This information is used in making the annual recommendation of vaccine composition. As in the last 15 years, influenza A viruses of both H3N2 and H1N1 subtypes and influenza B viruses have been isolated during the recent influenza season. Outbreaks in the northern hemisphere were largely caused by influenza B viruses which are similar to the B/Panama/45/90 reference strain. The proportion of influenza A increased later in the season and was predominantly of the H3N2 subtype, viruses similar to the recent A/Beijing/32/92 variant being most prevalent. The observed changes taking place will be discussed in the context of recent trends.

Tonsil surface and core cultures in recurrent tonsillitis: prevalence of anaerobes and beta-lactamase producing organisms

The bacterial flora of the tonsil surface and core was compared in patients suffering from recurrent tonsillitis. Surface swabs and tonsil core tissues were received as paired samples from 50 patients admitted for elective tonsillectomy. Analysis of paired samples from individual patients revealed differences in the bacterial flora of the tonsil core and the tonsil surface. Of 366 aerobic isolates, 30% grew from the surface alone, 26% from the core only and 44% from both sites. Of 290 anaerobic isolates, 35% grew from the surface alone, 33% from the core only and 31% from both sites. The total number of isolates from surface and core samples was similar (average 9.2 and 8.8, respectively). The range of species isolated was also similar for both surface and core samples, as was the proportion of organisms producing beta-lactamase from each site (10.7% and 9.5%, respectively). Eighty-two percent of patients carried beta-lactamase-producing organisms on either the tonsil surface or in the core tissue. A surface swab does not reliably reflect the types of organisms present in the tonsil core in individual patients. Anaerobes are a major component of tonsil surface and core bacterial flora in patients with recurrent tonsillitis. The high carriage rate of beta-lactamase-producing organisms in the tonsils should be considered when selecting antimicrobial therapy for persistent or recurrent tonsillitis.

Toxic inhibition of smooth muscle contractility by plant-derived sesquiterpenes caused by their chemically reactive alpha-methylenebutyrolactone functions

1. Previous studies have shown that extracts of feverfew (Tanacetum parthenium) and parthenolide, a sesquiterpene alpha-methylenebutyrolactone obtained from it, inhibit smooth muscle contractility in a time-dependent, non-specific and irreversible manner. 2. The hypothesis that this toxic effect is due specifically to the presence in the sesquiterpene lactone of the potentially reactive alpha-methylene function was tested on rabbit isolated aortic ring preparations. This was done (a) by comparing the effects of two plant-derived sesquiterpene lactones purified from yellow star thistle (Centaurea solstitialis): cynaropicrin (an alpha-methylenebutyrolactone) and solstitialin 13-acetate (lacking the alpha-methylene function), and (b) by chemically inactivating the alpha-methylene functions in cynaropicrin and parthenolide by reaction with cysteine. 3. The results show that the characteristic smooth muscle inhibitory profile is demonstrated by the two alpha-methylenebutyrolactones (parthenolide and cynaropicrin), but not by the compound lacking this functional group (solstitialin 13-acetate), or by those previously active compounds in which it has been inactivated with cysteine. 4. Thus the alpha-methylene function is critical for this aspect of the toxic pharmacological profile of the sesquiterpene butyrolactones, which are natural products widely distributed in the Compositae family of flowering plants.

Synthesis and anti-HIV activity of some novel diaryl phosphate derivatives of AZT

Novel diaryl phosphate triester derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridate chemistry. These materials were designed to act as membrane-soluble pro-drugs of the bio-active free nucleotides. In particular, novel parasubstituted diaryl phosphate derivatives were prepared. In vitro evaluation revealed the compounds to have a pronounced and selective antiviral effect, the magnitude of which varied considerably with the nature of the aryl substituent. In particular, strongly electron-withdrawing aryl substituents correlate with high anti-HIV potency in C8166 cells. Along with AZT, the compounds are poorly effective in JM cells, which appear to lack thymidine kinase, indicating the phosphates to act as pro-drugs of the nucleoside rather than of the free phosphate.

Role of virion M2 protein in influenza virus uncoating: specific reduction in the rate of membrane fusion between virus and liposomes by amantadine

The anti-influenza virus drug amantadine was shown to reduce the rate of fusion of liposomes with influenza A viruses whose replication is inhibited by this drug. The fusion with amantadine-resistant viruses was unaffected. Experiments with reassortant and mutant viruses showed that this effect was linked to the M2 protein and not to the haemagglutinin of the virus. The proton ionophore monensin, on the other hand, substantially increased the rate of fusion of the viruses tested. These results indicate that the kinetics of virus-liposome fusion can be modulated by the virus M2 protein, the target of amantadine action, and it is postulated that the M2 ion channel functions by transporting protons into the virion interior and facilitating virus uncoating.

Polymerase chain reaction for screening clinical isolates of corynebacteria for the production of diphtheria toxin

AIMS

To assess the performance of the polymerase chain reaction (PCR) when used to screen rapidly large numbers of corynebacteria for toxin production; and to determine the incidence of false positive PCR results with non-toxigenic Corynebacterium diphtheriae isolates.

METHODS

Eighty seven recent British isolates of corynebacteria were assayed by PCR. All isolates were assayed from both blood and tellurite agar within a five day period. Thirty three non-toxigenic isolates of C diphtheriae from six countries were also tested by PCR and by the Elek immunodiffusion assay.

RESULTS

There was complete concordance between the results of PCR and traditional methods on the recent British isolates, with one exception: an Elek positive "C ulcerans" isolate, which was PCR positive from tellurite but not from blood agar. One of the thirty three (3%) non-toxigenic isolates of C diphtheriae was PCR positive.

CONCLUSIONS

These results suggest that PCR compares favourably with traditional methods for the detection of toxigenic corynebacteria and that it represents a powerful new tool in the diagnosis of an old disease.

Inhibition of HIV infection by flavanoids

Of a variety of flavanoids, the flavans were generally more effective than flavones and flavanones in selective inhibition of HIV-1, HIV-2 or SIV infection. Studies of their effects on the binding of sCD4 and antibody to gp120 indicated that the effective compounds interact irreversibly with gp120 to inactive virus infectivity and block infection.

Influence of amantadine resistance mutations on the pH regulatory function of the M2 protein of influenza A viruses

Mutations in the influenza M2 membrane protein which confer resistance to the antiviral drug amantadine are exclusively located within the transmembrane region of the molecule. The influence of specific amino acid substitutions on the activity of the M2 protein in influenza A virus-infected cells is assessed in this report by their effects upon haemagglutinin (HA) stability and virus growth. A number of amino acid substitutions, e.g., L26H, A30T, S31N and G34E reduced the activity of the M2 protein of A/chicken/Germany/34 (Rostock) and caused a substantial increase in expression of the low-pH form of HA. The adverse effects of the mutations on virus replication were evident from changes selected during subsequent passage of the mutant viruses in the presence or absence of amantadine: reversion to wt, the acquisition of a second suppressor mutation in M2, or the appearance of a complementary mutation in HA which increased its pH stability. In contrast, 127T and 127S, mutations which were most readily selected following passage of the wt virus in the presence of drug, caused an increase in M2 activity. Furthermore, in double mutants the 127T mutation suppressed the attenuating effects of the A30T and S31N mutations on M2 activity. The influence of primary structure on the consequences of particular amino acid changes was further emphasized by the contrasting effects of the G34E mutation on the activities of two closely related proteins, causing an increase in the activity of the M2 of A/chicken/Germany/27 (Weybridge) as opposed to the decrease in activity of the Rostock protein. Estimates of differences in trans Golgi pH based on the degree of conversion of HA to the low-pH form, or complementation of differences in pH stability of mutant HAs, indicate that changes in M2 may influence pH within the transport pathway by as much as 0.6. The results thus provide further evidence that M2 regulates transmembrane pH gradients in the trans Golgi. Incompatibility between particular HA and M2 components and the selection of M2 mutants with suboptimal activity stresses the essential relationship between the structures and functions of these two virus proteins.

Maturation of influenza A virus hemagglutinin--estimates of the pH encountered during transport and its regulation by the M2 protein

The susceptibility of H7 influenza A viruses to the M2-mediated alteration in HA resulting from treatment with amantadine or rimantadine depends both on the pH stability of HA and the pH encountered during transport to the plasma membrane of the particular virus-infected cell. pH stabilities of a range of virus mutant HAs exhibited an inverse correlation with drug sensitivity and the proportion of low-pH HA expressed on the surface of infected cells in the absence of drug. The lowest pH encountered during transport was thus estimated from the proportion of HA expressed in its native conformation and its pH stability profile. Lower drug sensitivity and improved HA maturation of MDCK cells compared to that in CEF reflect the higher pH within the appropriate compartment of the former. Differences in apparent pH resulting from infection with two closely related virus strains, Rostock or Weybridge, e.g., approximately 6.0 and 5.4, respectively, in CEF, were abrogated by rimantadine treatment (pH approximately 5.2 in CEF) and were attributable to intrinsic properties of their respective M2 proteins. The greater activity of the Rostock M2, which was estimated to be capable of increasing vesicular pH by as much as 0.8 pH units, correlates with the lower pH stability of the HA. This emphasizes the essential relationship between the characteristics of the two virus proteins as well as the subtle role of M2 in regulating the pH of the transport pathway to protect the structural integrity of the hemagglutinin glycoprotein.

An ELISA utilizing immobilised snowdrop lectin GNA for the detection of envelope glycoproteins of HIV and SIV

A simple, reliable ELISA for the quantitative detection of the envelope glycoproteins of both HIV and SIV is described. It incorporates the snowdrop lectin GNA to capture the glycoprotein antigens and combines the high selectivity of GNA binding with its broad reactivity with the glycoproteins of HIV-1, HIV-2 and SIV.

Evidence that the amantadine-induced, M2-mediated conversion of influenza A virus hemagglutinin to the low pH conformation occurs in an acidic trans Golgi compartment

Amantadine treatment of cells infected with H7 strains of influenza A viruses causes an M2 protein-mediated conversion of hemagglutinin (HA) from its native to its low pH conformation. Immunofluorescence and electron microscopic observations showed that the structural alteration and hence drug action occur shortly after HA exits from the Golgi complex during its passage through the strans Golgi region. Using the DAMP/anti-DNP pH probe it is evident that virus infection causes increased acidity of the trans Golgi region and that vesicles containing low pH HA in amantadine-treated virus-infected cells are particularly acidic. These results indicate therefore that the alteration in HA is the direct consequence of exposure to an adverse low pH and provide further support for the conclusion that the M2 protein, the target of amantadine action, is involved in regulating vesicular pH, a function important for the correct maturation of the HA glycoprotein.

Aryl phosphate derivatives of AZT retain activity against HIV1 in cell lines which are resistant to the action of AZT

Novel aryl phosphate derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridate chemistry. These materials are designed to act as membrane-soluble pro-drugs of the bio-active free nucleotides. In vitro evaluation revealed the compounds to have a pronounced, selective antiviral activity, which, in one case, was more potent than the parent nucleoside AZT. The magnitude of the biological effect varied considerably with the nature of the phosphate-blocking group. Moreover, one of the compounds, a phosphoramidate, is particularly active in a cell line restrictive to the activity of AZT, due to poor phosphorylation therein. These data support the suggestion that the phosphate derivatives exert their biological effects via intracellular release of the nucleotide forms.

Regulation of pH by the M2 protein of influenza A viruses

Inhibition of the function of the M2 protein by amantadine can cause a conformational change in the haemagglutinin (HA) of H7 influenza A viruses and the consequent expression of the low pH form of the glycoprotein on the surface of virus-infected cells. Immunofluorescence studies showed that this conversion occurs shortly after HA exists from the Golgi complex apparently during its transport through the trans Golgi network and using the pH probe, DAMP/anti-DNP, that it is the direct result of reduced vesicular pH. The lowest pHs encountered were estimated using mutant HAs differing in pH stability to be approximately 5.2 and 5.6 in virus-infected CEF or MDCK cells, respectively, in the absence of functional M2. Depending on the particular M2, this protein was responsible for increases in vesicular pH of up to 0.8 units. The influence of mutations in both HA and M2 on the maturation of native HA illustrates the important relationship between the structural and functional properties of these two proteins. Using the fluorescent probe SNARF-1 the M2 protein was also shown to be largely responsible for the 0.3-0.4 unit reduction in intracellular pH of virus-infected cells. The data thus provide further evidence for the pH regulatory function of M2 and its importance for the maturation of the HA glycoprotein.

The occurrence of bacteraemia associated with the use of oral and nasopharyngeal airways

In order to determine whether placement of oral or nasopharyngeal airways during anaesthesia induces a significant bacteraemia, 36 ASA grade 1 or 2 patients undergoing body surface surgery, in whom it was anticipated that spontaneous respiration would be maintained, were randomly allocated to one of two groups. One group was given oral airways and the other, nasopharyngeal. A series of blood samples, which were taken before and after airway insertion, were cultured aerobically and anaerobically. Nasal and oral swabs were taken at the same time. Single isolates of Corynebacterium species and Acinetobacter species, together with two isolates of Staphylococcus epidermidis were grown from one culture bottle from 4 of the 36 patients studied. None of the oral or nasal swabs, or any of the subsequent or previous blood samples produced positive cultures for these organisms in these four patients. We believe that these results represent skin commensal contamination rather than bacteraemia in these four patients, and that bacteriological considerations should not influence decisions about the type of airway used during anaesthesia. However, prophylactic antibiotic therapy should still be provided for all high risk cases.

Emergence and transmission of influenza A viruses resistant to amantadine and rimantadine

Amantadine- and rimantadine-resistant viruses have been recovered from approximately 30% of patients treated for acute H3N2 subtype influenza and less often from their close contacts receiving drug prophylaxis. The limited data suggest that resistant viruses can emerge rapidly during drug therapy, as early as 2-3 days into treatment. These viruses retain their resistance phenotype during multiple passages in the laboratory and appear to be genetically stable in this regard. Studies in families and in nursing homes indicate that resistant isolates appear to be transmissible from treated patients and cause typical influenza in contacts receiving drug prophylaxis. It is unknown whether resistant human viruses are capable of competing with wild-type ones during multiple cycles of infection in the absence of the drug. These viruses appear to be pathogenic, and no evidence indicates that they differ from wild-type strains. Thus, these viruses clearly possess the biologic properties that are associated with clinically important drug resistance. However, limited information is available to assess their actual impact. It is unknown what degree of selective drug pressure would be required to cause substantial transmission of resistant viruses during community outbreaks. Natural selection of antigenic variants and disappearance of previous variants may prevent the emergence of viruses that have been altered in the genes coding both for the surface glycoproteins and for the M2 protein. However, the emergence of drug-resistant influenza viruses appears to pose potential clinical problems in certain epidemiologic situations involving close contact with treated patients.

Bacteriology of anal fistulae

Anal fistulae are said to arise from cryptoglandular infection of the anal glands, which lie within the intersphincteric space. The type and virulence of the micro-organism responsible may determine whether an anal fistula develops. The microbiology of chronic anal fistulae has not been reported previously. Twenty-five consecutive anal fistulae were studied prospectively (eight intersphincteric fistulae, 12 trans-sphincteric fistulae, two suprasphincteric fistulae, one extrasphincteric fistula, one superficial fistula, one anovaginal fistula). There were 18 men and seven women, with a median age of 42 (range 22-71) years. Patients with Crohn's disease or acute anorectal suppuration were excluded. In 18 patients, 0.1 ml granulation tissue from the track of the fistula was obtained and processed within 4 h using standard microbiological techniques. Sixty-nine isolates representing at least 17 species were obtained. The predominant organisms were Escherichia coli (22 per cent), Enterococcus spp. (16 per cent) and Bacteroides fragilis (20 per cent). The majority of the growths were obtained only from enrichment. Bacteria from only one patient grew at a dilution of 10(3). Granulation tissue from 25 patients was processed for mycobacterial culture, and Mycobacterium tuberculosis was grown from one patient. No other mycobacterium was isolated. The chronic inflammation in anal fistulae does not seem to be maintained by either excessive numbers of organisms or organisms of an unusual type.

Amantadine selection of a mutant influenza virus containing an acid-stable hemagglutinin glycoprotein: evidence for virus-specific regulation of the pH of glycoprotein transport vesicles

Mutants of influenza Rostock virus (H7N1 subtype) were selected for resistance to amantadine hydrochloride at concentrations of the antiviral drug known to affect the function of the virus M2 transmembrane protein. Sequence analysis revealed that three mutants had no changes in M2 but contained a lysine to isoleucine substitution in the hemagglutinin (HA) membrane glycoprotein at position 58 of HA2. The mutant viruses were found to fuse membranes at a pH value 0.7 lower than wild type and to exhibit changes in the conformation of their HAs specifically at the lower pH. The homologous lysine to isoleucine substitution was introduced by site-specific mutagenesis into the HA of X-31 influenza virus (H3 subtype), which was expressed by using vaccinia virus recombinants. The expressed HA also mediated membrane fusion and changed in conformation at a pH value 0.7 lower than wild type. These results indicate that increased acid stability of the HA obviates the consequences of the inhibition of M2 function by amantadine and provide further evidence for the role of M2 in regulating the pH of vesicles involved in glycoprotein transport to the cell surface.

Virulence of rimantadine-resistant human influenza A (H3N2) viruses in ferrets

The influence of rimantadine-resistance mutations on the virulence of human H3N2 viruses in ferrets was examined. The similarities in virulence of the drug-resistant mutants with single amino acid substitutions at three different locations, 27, 30, and 31, within the M2 sequence and their corresponding sensitive wild-type isolates contrasted with differences in virulence between the three pairs of viruses. These data provide further evidence that rimantadine-resistant viruses that emerge during treatment of patients with the drug are unaltered both in their growth characteristics and virulence.

Recovery of drug-resistant influenza A virus during therapeutic use of rimantadine

The therapeutic activity of rimantadine and its relationship to the shedding of drug-resistant influenza A virus were assessed in two randomized, double-blind, placebo-controlled trials involving patients with laboratory-documented influenza A virus (H3N2 subtype) illness of 2 days' duration or less. In a family-based study, rimantadine treatment for 10 days (24 children and adults) was associated with significant decreases in the number of days to a 50% reduction in symptoms (mean difference, 2.5 days), days of fever (1.6 days), and days of restricted activity (1.5 days) compared with the results obtained with placebo-treated patients (32 children and adults). Drug-resistant virus was recovered from eight (33%) of the rimantadine recipients on day 5. No differences in patient demographics or illness severity at the time of enrollment in the study were apparent between those who shed resistant virus and those who did not. Illness resolution tended to be slower in those who shed resistant virus compared with that in those who did not. In a study of adults treated for 5 days (six treated with rimantadine, six treated with placebo), resistant virus was recovered in three rimantadine recipients by day 3 of treatment. The results indicate that drug-resistant influenza A virus (H3N2) can be recovered from rimantadine-treated children and adults as early as 2 days after starting treatment, but that rimantadine retains a net therapeutic benefit compared with that of placebo.