Factors associated with virological suppression among HIV-positive individuals on highly active antiretroviral therapy in a multi-site Canadian cohort.

OBJECTIVE: The aim of the study was to evaluate time to virological suppression in a cohort of individuals who started highly active antiretroviral therapy (HAART), and to explore the factors associated with suppression. METHODS: Eligible participants were HIV-positive individuals from a multi-site Canadian cohort of antiretroviral-naïve patients initiating HAART on or after 1 January 2000. Viral load and CD4 measurements within 6 months prior to HAART initiation were assessed. Univariate and multivariate analyses were conducted using piecewise survival exponential models where time scale was divided into intervals (<10 months; ≥10 months). Virological suppression was defined as the time to the first of at least two consecutive viral load measurements <50 HIV-1 RNA copies/mL. RESULTS: A total of 3555 individuals were included in the study, of median age 40 years [interquartile range (IQR) 34-47 years]. Eighty per cent were male, 18% had a history of injecting drug use (IDU), and 13% presented with an AIDS-defining illness at baseline. The median time to suppression was 4.55 months (IQR 2.99-7.89 months). In multivariate analyses, older age, male sex, treatment in Ontario rather than British Columbia, non-IDU history, and having an AIDS diagnosis at baseline predicted increased likelihood of suppression. Patients with low baseline viral load were more likely to have suppression [4-5 log(10) copies/mL, hazard ratio (HR) 1.27, 95% confidence interval (CI) 1.18-1.38; <4 log(10) copies/mL, HR 1.49, 95% CI 1.32-1.68] than patients with baseline viral load ≥5 log(10) copies/mL; however, this effect ceased after 18 months of follow-up. Suppression was more likely with nonnucleoside reverse transcriptase inhibitors and ritonavir-boosted HAART. CONCLUSION: Identification of patients at risk for diminished likelihood of virological suppression will allow focusing of efforts and the utilization of resources to maximize the benefits of HAART.

Characters of aerated compost tea from immature compost that limit colonization of bean leaflets by Botrytis cinerea.

AIMS: The aim was to produce and characterize an aerated compost tea (ACT) that suppressed growth of the plant pathogen Botrytis cinerea. METHODS AND RESULTS: Three different open-windrow composts were sampled weekly from the early secondary mesophilic stage until maturity. Each 10kg of compost sample was extracted in 30 l of aerated water for 24, 48 or 72h. Relative to water, all batches of ACT applied to detached bean leaflets reduced lesion development following single-point inoculations of B. cinerea. There was a significant linear, inverse relationship between the internal windrow temperature of compost (≤51°C) used to prepare ACT and the extent of lesion development. Bacterial diversity in ACTs from one windrow was highest using compost sampled at 48°C. The compost weight-to-water volume ratios of 1:3, 1:10 or 1:30, using compost sampled from a fourth windrow at 50°C, also produced ACTs that reduced the growth of B. cinerea on bean leaflets. The '1 : 3' ACT, and to a lesser degree the same ACT filtered to remove micro-organisms, inhibited the germination of B. cinerea conidia. CONCLUSIONS: ACT produced using the methods reported here suppressed the growth of B. cinerea on bean leaflets, with an abundant and diverse microbial community likely to contribute to pathogen suppression. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of the use of immature compost to produce a pathogen-suppressive ACT, suggesting that compost stage is an important production variable.

Bone density comparison of selected carpal and tarsal bones: validation for their use in compression fracture fixation studies of scaphoid screws.

INTRODUCTION: To determine if trabecular, total and cortical bone densities of the capitate, navicular, cuboid, and first cuneiform were equivalent to those of the scaphoid, such that these bones could be used in place of the scaphoid in evaluating new headless scaphoid compression screws. METHODS: Fifty scaphoids, capitates, naviculars, cuboids, and first cuneiforms were harvested from fresh frozen cadavers. The trabecular, total and cortical bone densities were measured using pQCT technology and statistically compared. RESULTS: A paired t comparison between paired scaphoids and capitates showed no difference between the trabecular bone densities. However, their total bone and cortical densities were found to be different. An independent measures ANOVA comparison of the five bones, showed no significant difference in mean trabecular density between the capitates, naviculars and first cuneiforms when compared to the scaphoids. However, the mean total and cortical densities of the first cuneiforms were less than the scaphoids and the mean trabecular, total and cortical bone densities of the cuboids were all less than the scaphoids. DISCUSSION: Compression fracture fixation studies of headless compression screws could be conducted using the capitate, navicular, and first cuneiform as models of the scaphoid when the supply of scaphoids is limited.

Identifying environmental factors harmful to reproduction.

Reproduction is essential for the continuation of the species and for life itself. In biological terms, living and reproducing are essentially one and the same. There is, therefore, no sharp division between identifying factors harmful to reproduction and identifying factors harmful to life or vice versa. Detection of harmful factors requires balanced use of a variety of methodologies from databases on structure-activity relationships through in vitro and in vivo test systems of varying complexity to surveys of wildlife and human populations. Human surveys provide the only assured means of discriminating between real and imagined harmful factors, but they are time consuming and provide information after the harm has been done. Test systems with whole animals provide the best prospects for identifying harmful factors quickly, but currently available methods used for testing agrochemicals and drugs need a thorough overhaul before they can provide a role model. Whether there is a need for new methodology is doubtful. More certain is the need to use existing methodology more wisely. We need a better understanding of the environment--whatever it is--and a more thoughtful approach to investigation of multifactorial situations.

Assessment of current test procedures.

The belief that screening tests for teratogenicity are of low predictive value has many supporters who point to the inconsistency with which malformations are induced. However, to fault the test systems when such inconsistency is predictable from both the inherently unstable nature of a malformation and from fundamental principles of teratology, is unrealistic, and, as is shown, perhaps the greater faults lie with the critics. It is suggested by examples that, if attention was concentrated not on the inconsistent malformations but on more consistent embryopathic effects which in one form or another are always associated with malformations, the predictive value of the screening tests would appear in a more favorable light. Thus, even if malformations are not demonstrated, the range of conditions (dosages) in which they might occur can be determined. Such information, used in conjunction with that obtained from other preclinical studies, can then form a reasonably sound basis for extrapolation to man.

Neurobehavioral aspects of developmental toxicity testing.

Tests for detection of neurobehavioral changes in the offspring have been a regulatory requirement in developmental toxicity testing of drugs for almost 20 years. Keeping their purpose of hazard identification and risk assessment for humans in mind, investigators and agency reviewers have become deeply ingrained with some stereotyped behaviors with respect to such relevant issues as choice of animal species and data evaluation. Other problematic areas of study design and conduct, selection of litter representatives for testing, what methods to combine in a testing battery, and statistical treatment of results and their interpretation, will need more research and discussion in the future.

Pressures in the distal radioulnar joint: effect of surgical procedures used for Kienbock's disease.

Radial shortening and ulnar lengthening are two accepted surgical methods for treating Kienbock's disease. The effect of these procedures on the pressure within the distal radioulnar joint between the ulnar head and the sigmoid notch of the radius was experimentally evaluated in six fresh cadaver forearms. Radical shortening and ulnar lengthening led to increased pressure at the distal radioulnar articulation and caused shifting of the location of the center of pressure distally within the sigmoid notch. Radial displacement of the distal radial fragment at the time of radial shortening, however, decreased the peak pressures. Based on these experimental data, ulnar lengthening and radial shortening can be expected to alter the normal biomechanics of the distal radioulnar joint.

Frequency spectrum analysis of wrist motion for activities of daily living.

A frequency spectral analysis was performed on wrist motion data for 24 activities of daily living (ADLs). Wrist motion was measured using a triaxial electrogoniometer attached to the wrist using tape (for 12 subjects) and pins (for one subject). Results show that the average predominant frequency component of these ADLs was approximately 1 Hz with 75% of the spectral energy less than 5 Hz. The taped-on electrogoniometer, when compared with the pinned electrogoniometer, was adequate for calculating the predominant frequency component and spread of spectral data, but overestimated the magnitudes of the maximum spectral density and total area of the spectral curves. This discrepancy was largest for axial rotation.

Wrist joint motion simulator.

A computer controlled wrist joint motion simulator has been developed that actively moves forearms from cadavers through cyclic planar flexion-extension motions, planar radial-ulnar deviation motions, and combined motions such as circumduction. Hybrid position-force feedback control algorithms are used to determine the wrist flexor and extensor tendon forces necessary to achieve the desired motions. The simulator was used in a series of 12 fresh cadaver forearms to produce both flexion-extension and radial-ulnar deviation motions and was found to cause repeatable, physiological movements. In these experiments, the extensor tendon forces were greater than those of the flexors, typically by a factor of two.

The effect of massive transplacental iron loading.

Intravenous injection of three doses of 50 mg Fe/kg (total dose 150 mg Fe/kg) as iron dextran into rabbits late in pregnancy (days 26, 28, and 30 of gestation) reduced the weight gain of the dams and increased fetal mortality. Three doses of 20 mg Fe/kg also increased fetal mortality, while three doses of 5 mg Fe/kg were without effect. Liver and kidney iron concentrations of the dams and offspring were markedly increased at the time of parturition by treatment with a total dose of 150 mg Fe/kg. At 6 weeks after birth the liver and kidney iron concentrations of offspring from treated dams were comparable to those from control dams. The liver and kidney iron concentrations of the treated dams were significantly reduced from the levels found immediately post-partum. In the rat, four i.v. doses of 200 mg Fe/kg as iron dextran on days 17, 18, 19, and 20 of gestation (total dose 800 mg Fe/kg) produced tremors, reduced body weight gain, and reduced food consumption in the dams. The growth and survival of the offspring were adversely influenced by these effects on the dam. The liver iron concentration in offspring of rats treated with 800 and 400 mg Fe/kg was increased at parturition, but had returned to normal at 4 weeks of age. No iron-induced pathology was evident in the offspring of either rabbits or rats after 14 and 18 weeks, respectively.

The toxicity of beta-carotene.

The safety of beta-carotene, a widely distributed food colorant was assessed in tests with cells and in sub-chronic and chronic experiments with animals. Mutagenicity evaluations which included the standard Ames test and the micro-nucleus test of bone marrow cells from mice showed that beta-carotene exerted no mutagenic properties. Embryotoxicity studies in rats and rabbits showed that there was no evidence of embryotoxicity and a multiple generation study in rats showed that there was no interference with the reproductive function in rats given oral doses of up to 1000 mg/kg/day. Chronic toxicity was studied in a 2-year study with dogs in a toxicity/tumorigenicity study in rats and in a mouse carcinogenicity study. Histological findings in the livers of treated dogs and mice, but not in rats, included vacuolated cells with eccentric nuclei which were distributed in periportal areas and which were frequently associated with minimal lipid deposition. There was no evidence that the vacuolisation was dose-related. It was considered that the vacuolated cells were fat storage cells. There was no effect on the tumor profiles in the rat and the mouse studies.

Assessment of the teratogenic potential of surfactants. Part III--dermal application of LAS and soap.

The surfactant linear alkylbenzene sulphonate (LAS) was examined for embryotoxic and teratogenic potential following percutaneous administration. Solutions containing, 0.03, 0.3 and 3% LAS were applied to shaved skin during pregnancy days 2-13 in mice, 2-15 in rats and 1-16 in rabbits. Dosages employed were 0.5 ml/rat or mouse/day and 10 ml/rabbit/day. For comparison further groups of rats and mice were similarly treated with concentrations of 0.3, 3 and 30% of a standard soap solution. Marked maternal toxicity in the form of local skin reaction, irritability, weight loss and failure to maintain or establish pregnancy was evident in mice treated with LAS 3% or soap, 3 or 30%; marked local reaction and weight loss also occurred in rabbits receiving LAS 3% but the reduction in the number of pregnancies maintained was not significant. Moderate maternal toxicity was observed among mice treated with LAS, 0.3% and mild maternal toxicity in rats receiving LAS 3% or soap 30% and rabbits receiving LAS 0.3%. Effects on litter parameters were generally restricted to dosages causing marked maternal toxicity in mice, the principal effects being higher foetal loss (with consequent reduction in viable litter size) arising from an increased incidence of total litter losses. When dams showing total litter loss were excluded from the calculations, litter parameters were not unduly different from those of controls. Although LAS at 3% was considered to show marked maternal toxicity in the rabbit, the slightly higher foetal loss and lower litter size did not differ significantly from control values.

The effect of disodium 5-ribonucleotide on reproductive function over three generations in the rat.

Deitary levels of 0.1, 1.0 and 2.0% disodium 5-ribonucleotide were administered to rats of the CD strain over 3 generations, and the growth and reproductive performance were compared with those of a control group. Treatment did not appear to affect parent animals, as assessed by the incidence of mortality, bodyweight change, food consumption, mating performance, Pregnancy rate, Gestation Peroid, and post-mortem findings. Total litter loss, Litter size, Litter and mean pup weights, pup mortality and the incidence of skeletal or other variants in the offspring were unaffected by treatment at any dosage level. Additional organ weight analysis and skeletal staining of 10 males and 10 females from all groups, and the histological examination of 10 male and 10 females of the control and 2.0% level groups of the third generation did not provide any evidence of effects that could be related to treatment.

Effects of lindane upon reproductive function in a 3-generation study in rats.

A 3-generation study, involving the feeding of lindane at dietary concentrations of 25, 50 or 100 ppm to CD strain rats, did not reveal any adverse effects upon reproductive function as compared with that of control animals. There were no major malformations, while the distribution of minor variants was not compound or dose-related. An examination at 21 days of age of 10 males and 10 females F3B animals in each group revealed a dosage related tendency for increased liver weight and enlarged hepatocytes were seen in some control and treated animals. The relevance of these latter findings was considered of doubtful importance compared with the lack of effects on the growth and reproductive performance of the preceding generations.

Effect of lindane on pregnancy in the rabbit and rat.

There was no evidence of any teratogenic effect of lindane when administered during pregnancy at levels equivalent to 5, and 15 mg/kg body weight to New Zealand White rabbits from days 6 to 18 inclusive, or to CFY rats from days 6 to 16 inclusive. These findings are consistent with the negative teratogenicity results in mice mutagenicity studies and 3-generation rat reproduction studies already reported.

Trypan blue: identification and teratogenic and oncogenic activities of its coloured constituents.

Three coloured substances frequently present as contaminants in commercial samples of trypan blue have been identified as those monoazo dyes in which 4-amino-3,3'-dimethyl-biphenyl, 4-amino-3,3'-dimethyl-4'-hydroxy-biphenyl or omicroc-tolidine are coupled to H-acid. These dyes have been synthesized and, together with purified samples of trypan blue, tested for teratogenic activity in mice and oncogenic activity in rats. Unpurified trypan blue was both teratogenic and oncogenic; purified trypan blue, was teratogenic but only weakly oncogenic; the monoazo dyes possessed neither activity. It is concluded that the main blue component of trypan blue is the teratogenic principle and that some as yet unidentified component of the purple fraction either is the main oncogenic principle or potentiates the action of the blue component.

Radiography and computerized tomography in the diagnosis of incongruity of the distal radio-ulnar joint. A prospective study.

The diagnosis of subluxation or dislocation of the distal radio-ulnar joint may be difficult to confirm by routine radiographs. We undertook a prospective evaluation of fifteen patients with acute or chronic pain in the distal radio-ulnar joint, using both standardized radiographs and computer assisted tomography. In the absence of a deformity of the distal end of the radius, a lateral radiograph made with the wrist in the neutral position accurately revealed incongruency of the distal radio-ulnar joint. When pain or cast immobilization prevented optimum positioning of the wrist for radiography, or when a deformity of the distal end of the radius was present, computer assisted tomography gave a more accurate determination of the congruency of the joint.

Tri-isobutylphosphate: a prenatal toxicity study in rats.

To assess the prenatal toxicity to rats of the anti-foaming agent, tri-isobutylphosphate (CAS 126-71-6), a study was conducted in which daily dosages of 0, 100, 300 and 1000 mg/kg were administered to different treatment groups by gavage from day 6 to 15 of pregnancy. Dams were killed and foetuses examined on day 20 of pregnancy. Maternal effects during the dosing period included a dosage-related increase in the frequency, persistence and severity of post dosing salivation in all test groups and significantly increased water consumption at 1000 mg/kg. Bodyweight gain at 1000 and 300 mg/kg was lower than that of controls but the differences were not statistically significant. The lowest dosage of 100 mg/kg could be considered as the maternal 'lowest observed adverse effect level' (LOAEL) or 'no observed adverse effect level' (NOAEL) according to whether increased salivation is perceived to be a true toxic effect or simply a reaction to the taste of the test material. Neither litter values nor the prevalence of foetuses with abnormalities indicated any embryotoxic effects (including teratogenicity) at any dosage. The most notable feature of the results was the occurrence of a cluster of foetuses with the congenital abnormality referred to as 'hunched posture syndrome' or 'squat foetus syndrome'. However, the incidence of this finding was similar to that noted among background data for the same strain and, in the absence of any other embryotoxic findings, was considered likely to have arisen coincidentally.

The toxicology of a ganglioside extract (Cronassial).

The accepted animal toxicity studies indicate that the ganglioside mixture extracted and purified from the bovine brain cortex (Cronassial) is without detectable toxicity. It did not induce any adverse effects on any of the characteristics of reproduction and it is not antigenic.

Introduction to (pre)screening methods.

In summation I start this session with the opinion that in vitro methods cannot be considered as adequate replacements for entire animals at the level of regulatory testing. But, when used to identify mechanisms of action, they can be extremely useful as secondary stage supporting studies. They are of doubtful value for general purpose, broad spectrum screening of single chemical entities or for priority selection of unrelated chemicals. They can be of value for priority selection of homologous series with a known, specific effect on reproduction or development. Such situations are most likely to be present in chemical and drug manufacturing industries where judicious use of in vitro methods in an integrated approach could reduce the number of failures at the later stage of full scale testing. Whether I will need to revise my opinions at the end of this session will depend upon what our speakers have to offer.