Characteristics of a widespread community cluster of H275Y oseltamivir-resistant A(H1N1)pdm09 influenza in Australia.

BACKGROUND: Oseltamivir resistance in A(H1N1)pdm09 influenza is rare, particularly in untreated community cases. Sustained community transmission has not previously been reported. METHODS: Influenza specimens from the Asia-Pacific region were collected through sentinel surveillance, hospital, and general practitioner networks. Clinical and epidemiological information was collected on patients infected with oseltamivir-resistant viruses. RESULTS: Twenty-nine (15%) of 191 A(H1N1)pdm09 viruses collected between May and September 2011 from Hunter New England (HNE), Australia, contained the H275Y neuraminidase substitution responsible for oseltamivir resistance. Only 1 patient had received oseltamivir before specimen collection. The resistant strains were genetically very closely related, suggesting the spread of a single variant. Ninety percent of cases lived within 50 kilometers. Three genetically similar oseltamivir-resistant variants were detected outside of HNE, including 1 strain from Perth, approximately 4000 kilometers away. Computational analysis predicted that neuraminidase substitutions V241I, N369K, and N386S in these viruses may offset the destabilizing effect of the H275Y substitution. CONCLUSIONS: This cluster represents the first widespread community transmission of H275Y oseltamivir-resistant A(H1N1)pdm09 influenza. These cases and data on potential permissive mutations suggest that currently circulating A(H1N1)pdm09 viruses retain viral fitness in the presence of the H275Y mutation and that widespread emergence of oseltamivir-resistant strains may now be more likely.

Increased detection in Australia and Singapore of a novel influenza A(H1N1)2009 variant with reduced oseltamivir and zanamivir sensitivity due to a S247N neuraminidase mutation.

A novel influenza A(H1N1)2009 variant with mildly reduced oseltamivir and zanamivir sensitivity has been detected in more than 10% of community specimens in Singapore and more than 30% of samples from northern Australia during the early months of 2011. The variant, which has also been detected in other regions of the Asia-Pacific, contains a S247N neuraminidase mutation. When combined with the H275Y mutation, as detected in an oseltamivir-treated patient, the dual S247N+H275Y mutant had extremely high oseltamivir resistance.

Oseltamivir-resistant influenza viruses circulating during the first year of the influenza A(H1N1) 2009 pandemic in the Asia-Pacific region, March 2009 to March 2010.

During the first year of the influenza A(H1N1) 2009 pandemic, unprecedented amounts of the neuraminidase inhibitors, predominantly oseltamivir, were used in economically developed countries for the treatment and prophylaxis of patients prior to the availability of a pandemic vaccine. Due to concerns about the development of resistance, over 1,400 influenza A(H1N1) 2009 viruses isolated from the Asia-Pacific region during the first year of the pandemic (March 2009 to March 2010) were analysed by phenotypic and genotypic assays to determine their susceptibility to the neuraminidase inhibitors. Amongst viruses submitted to the World Health Organization Collaborating Centre for Reference and Research in Melbourne, Australia,oseltamivir resistance was detected in 1.3% of influenza A(H1N1) 2009 strains from Australia and 3.1% of strains from Singapore, but none was detected in specimens received from other countries in Oceania or south-east Asia, or in east Asia. The overall frequency of oseltamivir resistance in the Asia-Pacific region was 16 of 1,488 (1.1%). No zanamivir-resistant viruses were detected. Of the 16 oseltamivir-resistant isolates detected, nine were from immunocompromised individuals undergoing oseltamivir treatment and three were from immunocompetent individuals undergoing oseltamivir treatment. Importantly, four oseltamivir-resistant strains were from immunocompetent individuals who had not been treated with oseltamivir, demonstrating limited low-level community transmission of oseltamivir-resistant strains. Even with increased use of oseltamivir during the pandemic, the frequency of resistance has been low, with little evidence of community-wide spread of the resistant strains. Nevertheless, prudent use of the neuraminidase inhibitors remains necessary, as does continued monitoring for drug-resistant influenza viruses.

A new pandemic influenza A(H1N1) genetic variant predominated in the winter 2010 influenza season in Australia, New Zealand and Singapore.

Pandemic H1N1 influenza virus is of global health concern and is currently the predominant influenza virus subtype circulating in the southern hemisphere 2010 winter. The virus has changed little since it emerged in 2009, however, in this report we describe several genetically distinct changes in the pandemic H1N1 influenza virus. These variants were first detected in Singapore in early 2010 and have subsequently spread through Australia and New Zealand. At this stage, these signature changes in the haemagglutinin and neuraminidase proteins have not resulted in significant antigenic changes which might make the current vaccine less effective, but such adaptive mutations should be carefully monitored as the northern hemisphere approaches its winter influenza season.

An in vivo model for investigations of mechanical signal transduction in trabecular bone.

The premise that bone cells are able to perceive and respond to mechanical forces is well accepted. This article describes the use of an in vivo hydraulic bone chamber for investigations of mechanical signal transduction. The servohydraulic loading mechanism was activated to apply a controlled compressive load to the woven trabecular bone that formed in one chamber, while the contralateral chamber served as an unloaded control. Specimens were harvested at a series of postload time points, and the cellular response to loading was evaluated by cytochemical, histomorphometric, and Northern blot analysis. A repetitive daily load stimulus elicited osteoblast biosynthetic activity characterized by an initial increase in type I procollagen by day 3 and a subsequent rise in alkaline phosphatase (ALP) activity after the sixth daily load episode. Application of a single load episode induced a biphasic pattern of c-fos and zif-268 gene expression with up-regulation at 30 minutes, down-regulation at 12 h, and up-regulation 24 h after the mechanical stimulus. The results show that a synchronized pattern of bone cell activity and gene expression occurs in response to controlled mechanical stimulation and that candidate load-responsive molecular mediators can be evaluated easily by this model.

Mechanical stimulation of tissue repair in the hydraulic bone chamber.

A hydraulically activated bone chamber model was utilized to investigate cellular and microstructural mechanisms of mechanical adaptation during bone repair. Woven trabecular bone and fibrotic granulation tissue filled the initially empty chambers by 8 weeks postimplantation into canine tibial and femoral metaphyses. Without mechanical stimulation, active bone remodeling to lamellar trabecular bone and reconstitution of marrow elements were observed between 8 and 24 weeks. In subsequent loading studies, the hydraulic mechanism was activated on one randomly chosen side of 10 dogs following 8 weeks of undisturbed bone repair. The loading treatment applied an intermittent compressive force (18 N, 1.0 Hz, 1800 cycles/day) for durations of a few days up to 12 weeks. Stereological analysis of three-dimensional microcomputed tomography images revealed an increase in trabecular plate thickness and connectivity associated with the loaded repair tissue microstructure relative to unloaded contralateral controls. These microstructural alterations corresponded to an over 600% increase in the apparent modulus of the loaded bone tissue. A significant increase in the percentage of trabecular surfaces lined by osteoblasts immunopositive for type I procollagen after a few days of loading provided further evidence for mechanical stimulation of bone matrix synthesis. The local principal tissue strains associated with these adaptive changes were estimated to range from approximately -2000 to +3000 mustrain using digital image-based finite element methods. This study demonstrates the sensitivity of bone tissue and cells to a controlled in vivo mechanical stimulus and identifies microstructural mechanisms of mechanical adaptation during bone repair. The hydraulic bone chamber is introduced as an efficient experimental model to study the effects of mechanical and biological factors on bone repair and regeneration.

Midazolam kinetics in women of two age groups.

Midazolam kinetics were determined in 11 younger (22 to 30 yr) and 11 older (50 to 60 yr) women to determine age-related differences in the kinetics of this water-soluble benzodiazepine. Midazolam, 0.2 mg/kg, was injected intravenously over 30 sec for induction of anesthesia that was maintained with 67% nitrous oxide in oxygen and intravenous fentanyl doses. There were no differences between the groups with respect to awakening times or plasma concentrations. Midazolam kinetics were described by a three-compartment open mamillary model. The only differences were small increases in the slow and total volumes of distribution in the older women. The kinetics we determined, including the steady-state volume of distribution of 1.23 l/kg and the elimination clearance of 419 ml/min, are in excellent agreement with those reported by others. Our data suggest that midazolam has advantages over other benzodiazepines, not only because of its water solubility and shorter elimination t1/2, but also because of little change in its kinetics with age.

A minor modification of residue 1 in potent vasopressin antagonists dramatically reduces agonist activity.

[1-(beta,beta-Pentamethylene-beta-mercaptopropionic acid),2-(O-ethyl)-D- tyrosine,4-valine,9-desglycine]arginine-vasopressin (SK&F 101926, 1), a potent in vivo and in vitro vasopressin V2 receptor antagonist, was recently tested in human volunteers and shown to be a full antidiuretic agonist. A new animal model for vasopressin activity has been developed in dogs that duplicates the clinical agonist findings exhibited with SK&F 101926. In this model we have discovered that substitution of a cis-4'-methyl group on the Pmp moiety at residue 1 of vasopressin antagonists results in substantially reduced agonist activity compared to the unsubstituted molecule (SK&F 101926). The corresponding analogue with a trans-4'-methyl group exhibits more agonist activity than the cis molecule. These findings can be explained by viewing the biological activities of compounds such as 1 as the interaction of the vasopressin receptor with a number of discrete molecular entities, conformers of 1, which present different pharmacophores. Models have been developed to assist in the understanding of these results.

Effect of cyclo-oxygenase blockade on the renal actions of vasopressin and SK&F 105494 in the rhesus monkey.

1. Vasopressin administration to pentobarbitone-anaesthetized, hydrated female rhesus monkeys resulted in dose-dependent increases in urine osmolality and decreases in urine flow. Treatment with indomethacin at a dose (5 mg kg-1, i.v.) that reduced urinary prostaglandin E2 (PGE2) excretion by at least 70% did not alter these responses. 2. The vasopressin antagonist, SK&F 105494 (Pas1,6D-Tyr(Et)2Val4Arg7D-Arg8desGly9 arginine vasopressin; 10 micrograms kg-1), caused significant rightward shifts (P less than 0.05) of both the vasopressin-urine osmolality and the vasopressin-urine flow dose-response curves. Treatment with indomethacin did not alter these responses. 3. SK&F 105494 alone or after indomethacin treatment had minimal effects on urine osmolality and urine flow. 4. The data indicate that indomethacin does not alter the antidiuretic activity of vasopressin in the rhesus monkey and that SK&F 105494 is a potent antagonist of exogenous vasopressin with minimal agonist activity.

Haemorrheological effects of prostaglandin E1 infusion in Raynaud's syndrome.

Eighteen patients with severe Raynaud's syndrome had impaired deformability of erythrocytes, as measured by filtration through 5 micron diameter pores, compared with 19 healthy controls. The patients were given prostaglandin E1 (PGE1) or placebo by intravenous infusion for 72 h to assess the haemorrheological action of PGE1. Contrary to a previous report, PGE1 did not improve erythrocyte filterability. Infusion of PGE1 did, however, evoke an acute phase response with hyperproteinaemia and a leucocytosis and is a potentially important mediator of this stress response in patients with vascular disease.

Erythrocyte deformability in peripheral occlusive arterial disease.

A rheological study of 32 patients with peripheral occlusive arterial disease (POAD), compared with 32 matched healthy controls, has shown no loss of erythrocyte deformability as measured by filtration methods (using initial flow rate and positive pressure instruments, polycarbonate and silver membranes, and 3 microns and 5 microns diameter pores) or by viscometry (using laser visco-diffractometric and high shear rate viscosity methods). Erythrocyte ATP concentration in POAD was also normal. Patients with POAD showed a small (4 fl) increase in mean erythrocyte volume, associated with a raised serum gamma-glutamyl transpeptidase concentration, which correlated with erythrocyte filtration and viscometric measurements. Previous reports of impaired blood filterability in POAD probably reflect the effects of accompanying leucocytosis, plasma hyperfibrinogenaemia, or an increase in erythrocyte size, but not an intrinsic loss of erythrocyte deformability.

Mechanical stimulation induces pp125(FAK) and pp60(src) activity in an in vivo model of trabecular bone formation.

Utilizing an in vivo model of trabecular bone formation, we demonstrated the temporal and spatial activation of pp125(FAK) in response to specific mechanical load stimuli. Bone chambers equipped with hydraulic actuators were aseptically inserted into each proximal tibial metaphysis of adult, male dogs under general anesthesia. The load stimulus consisted of a trapezoidal waveform, with a maximum compressive load of 17.8 N, loading rate of 89 N/s, at 1 Hz frequency. One chamber was loaded for 2 (120 cycles), 15 (900 cycles), or 30 min (1,800 cycles), whereas the contralateral chamber served as unloaded control. Bone chambers were biopsied at postload time points of 0, 15, and 45 min. Load-induced activation of FAK was rapid, and the duration of activation was dependent on the number of applied load cycles. Mechanical stimulation increased the association of FAK with Src and the time course of complex formation paralleled the temporal activation of FAK. Evaluation of cryosections revealed prominent FAK immunoreactivity among marrow fibroblasts and stromal cells.

Comparison of three doses of oral ciramadol and placebo for the treatment of moderate to severe postoperative pain.

Ciramadol, 20, 40, or 60 mg, or a placebo was administered orally, double blind, to patients complaining of moderate (N = 89) or severe (N = 80) postoperative pain to determine the lowest effective dose. The highest dose used for moderate pain, 40 mg, was statistically more effective than placebo as measured by pain intensity differences and pain relief scores. The highest dose used to treat severe pain, 60 mg, was also more effective statistically than placebo and the lower doses of ciramadol at certain points during the 6-hour observation period. Drowsiness was minimal, and side effects were infrequent and mild in intensity. We conclude that 40 mg ciramadol for moderate postoperative pain and 60 mg ciramadol for severe postoperative pain would be the minimal oral doses to compare with standard analgesics in future studies.

Intramuscularly administered ciramadol for management of postoperative pain: a comparative study.

Efficacy and safety of the analgesic ciramadol in the management of postoperative pain was evaluated in 139 healthy patients given single, double-blind, intramuscular injections of either 30 mg ciramadol, 60 mg ciramadol, 10 mg morphine or 0.9% saline on the first or second postoperative day. Differences in pain intensity and relief of pain, changes from baseline on a pain analog scale, percentage of patients with moderate or greater pain relief, and cumulative treatment failures were measured for 6 hours after injection. Morphine proved to be superior to all other treatments. Neither dose of ciramadol could be statistically differentiated from placebo. During the first hour after administration, some measurements showed that 30 mg ciramadol was superior to 60 mg ciramadol. Patients experienced little or no drowsiness in any of the four groups, and other side effects were transient and required no specific therapy. Some patients experienced an acute increase in pain intensity after administration of 60 mg ciramadol; this possibly represents antagonism of the residual effect of the previous narcotic. This study must be interpreted with the knowledge that ciramadol, an agonist-antagonist analgesic, was administered to patients who had been receiving narcotic analgesics before entering the study. Future studies of ciramadol given as the sole analgesic may more clearly define its efficacy in the management of postoperative pain.

Dose-finding and pharmacokinetic study of intramuscular midazolam.

Ten healthy male volunteers received intramuscular (IM) doses of 0.050, 0.075, and 0.100 mg/kg midazolam hydrochloride or its vehicle (placebo) in a double-blind manner until a dose producing adequate preanesthetic sedation was administered. Level of sedation, degree of impairment of psychomotor function, existence of antegrade amnesia, and incidence of side effects were evaluated after each dose. An adequate level of sedation (awake/drowsy or asleep/easily responds to verbal command for at least one hour after drug administration) was produced, beginning shortly after drug administration, in eight of the volunteers by 0.075 mg/kg; the dose producing the same effect (the optimal dose) was 0.050 mg/kg for the oldest volunteer, and the other volunteer required 0.100 mg/kg. Sedation lasted no more than four hours after administration of the optimal dose. The optimal dose in each volunteer produced an impairment of psychomotor function that lasted no more than six hours and antegrade amnesia that lasted no more than two hours. Mild erythema at the injection site occurred infrequently. The pharmacokinetic variables describing the absorption and disposition of midazolam were determined in five of the volunteers. Pharmacokinetic studies indicated that midazolam hydrochloride is absorbed rapidly from IM injection sites; this consistent with the observation of a rapid onset of sedation. The relatively high elimination clearance of midazolam after IM administration is similar to that reported after intravenous administration. The results of this study suggest that midazolam hydrochloride 0.075 mg/kg IM provides sedation and amnesia that is satisfactory for preanesthetic medication but does not last too long into the recovery period.

Relative effects of wound healing and mechanical stimulus on early bone response to porous-coated implants.

We hypothesized that early bone adaptation to well fixed porous-coated implants is influenced more by wound healing than by mechanical loading. To test this hypothesis, two groups of dogs with identical, hydraulically controlled porous-coated implants interference fit within distal femoral trabecular bone were used. One group had no load: the other had 35 N of load applied to the implants. At 5 weeks after surgery, the resulting adaptation of bone around the implants was quantified on a cellular basis by cytochemical analysis of type-I procollagen synthesis and on a structural basis using three-dimensional micro-computed tomography imaging. The percentage of trabecular surfaces covered by osteoblasts expressing type-I procollagen was significantly increased in bone surrounding the implant in both groups compared with contralateral control bone tissue. There was no difference between the groups with no load or 35 N of load. In addition, measures of trabecular bone structure did not differ significantly between the load and no-load groups. Taken together, these results suggest that wound healing plays a much greater role in the early response of bone to well fixed porous-coated implants than does mechanical stimulus.

Effects of ruminative and distracting responses to depressed mood on retrieval of autobiographical memories.

Four studies explored the effects of self-focused rumination vs. distraction on dysphoric and nondysphoric students' retrieval of autobiographical memories. Dysphorics induced to ruminate subsequently recalled more negatively biased autobiographical memories in free recall (Study 1) and in response to prompts for memories (Study 2) than either dysphorics who first distracted themselves from their mood or nondysphoric controls. In Study 3, dysphoric rumination led students to recall negative events as occurring relatively frequently in their lives and positive events as occurring relatively infrequently. In Study 4, judges scored transcripts of participants' thoughts as expressed aloud while engaging in rumination or distraction. Codings revealed that dysphoric ruminators spontaneously generated memories that were more negative than those of the other three groups. Implications of a ruminative response style for progress in therapy, as well as for enhancing dysphoria and negatively biased cognitive processes, are discussed.

Why ruminators are poor problem solvers: clues from the phenomenology of dysphoric rumination.

The phenomenology of dysphoric rumination and its consequences for problem solving were explored in 3 studies. In Study 1, self-focused rumination, compared with distraction, led dysphoric participants to rate their own biggest problems as severe and unsolvable and to report a reduced likelihood of actually implementing their solutions. Clues into the mechanisms behind these findings were explored in Study 2. The results showed that dysphoric ruminative thought is characterized by a focus on personal problems combined with a negative tone, self-criticism, and self-blame for problems as well as reduced self-confidence, optimism, and perceived control. Finally, Study 3 revealed a direct relationship between the negatively biased content of ruminative thoughts and reduced willingness to solve one's problems. Implications of these findings for the consequences of self-focused rumination are discussed.

An algorithm for approximate crinkle artifact compensation in pressure-sensitive film recordings.

An objective, empirically based image-processing technique was devised to compensate for the presence of crinkle artifact in Pressensor pressure-sensitive film recordings. A spherical indentor was used to produce film stains which deliberately included radially directed artifact streaks, superimposed upon otherwise smooth, nearly axisymmetric stain recordings. An interactive, threshold-based search algorithm was developed to delineate explicitly the perimeters of specific artifacts present within manually (cursor) circumscribed regions where crinkle features were visually apparent. Three mathematical artifact transformation operators were parametrically evaluated in terms of their ability to approximate objectively the corresponding artifact-free axisymmetric pressure fields. All three operators were found to reduce substantially the quantitative deviation from the idealized distributions. When appropriately tuned transformation operators were applied to typical in vitro intraarticular contact stains, the visual prominence of crinkle artifact features was markedly reduced.

Trabecular bone adaptation to variations in porous-coated implant topology.

Trabecular bone adaptation adjacent to porous-coated platen implants embedded within canine distal femoral metaphyses was evaluated following 24 weeks of daily compressive loading. The in vivo experimental model delivered controlled loads to five different platen implant topologies with variations in platen shape and porous coating distribution. Adaptive changes were evaluated based on three-dimensional stereological analyses of trabecular bone architecture underneath each platen and non-destructive mechanical tests of platen construct stiffness. Fully coated cylindrical platen designs possessed the highest construct stiffness in both tension and compression. Changes in local trabecular bone morphology were also found to be significantly influenced by platen implant topology. Cylindrical platens with fully coated bottom surfaces were associated with greater decreases in trabecular bone volume and connectivity than cylindrical platens with smooth bottom surfaces or fully coated conical platens. Comparisons to site-matched contralateral control bone volumes across all platen designs indicated significant decreases in the average bone volume fraction, trabecular plate number, and connectivity within experimental samples, but no change in trabecular plate thickness. In addition, analyses of microstructural anisotropy revealed a 20 degrees or 20.2 degrees trabecular reorientation towards the axis of loading in experimental tissue. This study demonstrates that trabecular bone adaptation near porous-coated surfaces is influenced by variations in local implant topology and provides insight into specific mechanisms of implant-mediated microstructural adaptation.