Population analysis of the pharmacokinetics and pharmacodynamics of RWJ-270201 (BCX-1812) in treating experimental influenza A and B virus in healthy volunteers

OBJECTIVE

Our objective was to assess the pharmacokinetics and pharmacodynamics of RWJ-270201 (BCX-1812), an oral neuraminidase inhibitor for the treatment of influenza A and B virus in healthy volunteers.

METHODS

This was a double-blind, randomized, placebo-controlled, parallel group study. A total of 80 adult male and female subjects were enrolled for the influenza A challenge study. This was a 5-arm study (100 mg/qd, 200 mg/qd, 200 mg/bid, 400 mg/qd, and placebo). In the challenge B virus model, 60 subjects were enrolled for a 3-arm study (800 mg on Day 1 followed by 400 mg on Days 2-5; 800 mg on Days 1-5; and placebo). The pharmacokinetics of RWJ-270201 (BCX-1812) were characterized with the use of a population approach and were described by a 2-compartmental model with first-order absorption and elimination. The pharmacodynamic data, mean log viral titers, were described with the use of an empirical equation relating the viral growth and the effect of drug on changes in viral titers.

RESULTS

Pharmacokinetic analyses show that weight was the most significant covariate for all estimated pharmacokinetic parameters. The pharmacodynamic data, mean log viral titers showed a decrease in viral titers with increase in plasma exposure. The decrease in viral titer started to occur 12 hours following the drug dosing, and viral suppression lasted 72 hours to 96 hours. The exposures associated with a 50% decrease in viral titers were 1089 ng-h/mL and 1898 ng-h/mL, respectively.

CONCLUSIONS

A PK/PD model was well utilized to characterize the effect of RWJ-270201 (BCX-1812) on the influenza A and B virus. The results from this model showed that both the loading dose and the standard dose regimens are efficacious against A and B virus. RWJ-270201 (BCX-1812) is under clinical development for the treatment of influenza A and B infections in adult and high-risk populations. It is a potent and selective inhibitor of both influenza A and B virus neuraminidases and inhibits the viral cleavage of sialic acid from cell surface glycoproteins and glycolipids. Consequently, RWJ-270201 (BCX-1812) prevents infection by stopping the release of newly formed virus from the surface of infected cells and preventing viral spread across the mucous lining of the respiratory tract. It therefore represents an attractive agent for antiviral therapy.

Assessing population health care need using a claims-based ACG morbidity measure: a validation analysis in the Province of Manitoba

OBJECTIVES

To assess the ability of an Adjusted Clinical Group (ACG)-based morbidity measure to assess the overall health service needs of populations. Data Sources/Study Setting. Three population-based secondary data sources: registration and health service utilization data from fiscal year 1995-1996; mortality data from vital statistics reports from 1996-1999; and Canadian census data. The study included all continuously enrolled residents in the universal health care plan in Manitoba.

STUDY DESIGN

Using 60 small geographic areas as the units of analysis, we compared a population-based "ACG morbidity index," derived from individual ACG assignments in fiscal year 1995-1996, with the standardized mortality ratio (ages < 75 years) for 1996-1999. Key variables included a population-based socioeconomic status measure and age- and sex-standardized physician utilization ratios.

DATA EXTRACTION METHODS

The ACGs were assigned based on the complement of diagnoses assigned to persons on physician claims and hospital separation abstracts. The ACG index was created by weighting the ACGs using average health care expenditures.

PRINCIPAL FINDINGS

The ACG morbidity index had a strong positive linear relationship with the subsequent rate of premature death in the small areas of Manitoba. The ACG index was able to explain the majority of the relationships between mortality and both socioeconomic status and physician utilization.

CONCLUSIONS

In Manitoba, ACGs are closely related to premature mortality, commonly accepted as the best single indicator for health service need in populations. Issues in applying ACGs in settings where needs adjustment is a primary objective are discussed.

Diabetic retinopathy among self reported diabetics in southern India: a population based assessment

AIMS

To estimate the prevalence of diabetic retinopathy among self reported diabetics in a population of southern India.

METHODS

A cross sectional sample of subjects aged 50 years and older was selected using a cluster sampling technique from Palakkad district of Kerala state. Eligible subjects were identified through a door to door survey. Ocular examinations including visual acuity and anterior and posterior segment examinations were performed at preselected sites within clusters. History of diabetes was elicited, and height, weight, and blood pressure were measured for all subjects.

RESULTS

Among the 5212 examined people (92% response rate), 68 (26.2%) of 260 people with self reported history of diabetes had diabetic retinopathy. The age-sex adjusted prevalence of diabetes among people aged 50 years and older was 5.1% (95% CI 3.9, 6.3, deff 4.33) and of diabetic retinopathy among the diabetics was 26.8% (95% CI: 19.2, 34.4, deff 1.99). Non-proliferative diabetic retinopathy (94.1%) was the most common form of retinopathy seen. Two eyes were blind (presenting vision <6/60) as a result of retinopathy.

CONCLUSION

Preventive strategies have to be evolved to ensure that blindness due to diabetic retinopathy does not become a public health problem in India. Further studies are required to understand the risk factors for retinopathy and vision loss in this population.

Polymorphism of simple sequence repeats reveals gene flow within and between ectomycorrhizal Suillus grevillei populations

•  Gene flow within and between two populations of the ectomycorrhizal fungus Suillus grevillei is shown here using co-dominant simple sequence repeat (SSR) markers. •  Co-dominant SSR markers were developed for S. grevillei. Distribution and frequency of alleles at the three codominant SSR markers were analysed within two S. grevillei populations in two Larix Kaempteri stands located 700 m apart. •  Among eight SSR loci isolated from S. grevillei, five loci (designated SG1-5) were polymorphic and SG1-3 were co-dominant. Genets (73) previously identified by inter-simple sequence repeat markers at the Larix stands were divided by the combination of SG1-3 into 22 genotypes. Most of the SSR genotypes were spatially clustered, indicating that the dispersal distance of S. grevillei spores was relatively short. •  There was no conspicuous genetic differentiation within or between the two S. grevillei populations, indicating extensive gene flow. The spread of alleles within or between populations might be by repeats of short-distance spore dispersal rather than long-distance spore dispersal.

The current status of primary prevention in coronary heart disease

During the second part of the twentieth century, research advances caused a substantial decline in the rate of coronary heart disease. The decline lasted from the mid-1960s until the early 1990s and occurred primarily in Western countries. However, an unfavourable trend in coronary heart disease related mortality has gradually developed during the 1990s, with cardiovascular diseases anticipated to remain the main cause of overall mortality for the foreseeable future. The present paper aims at analyzing the current status of the main determinants of population-wide coronary heart disease prevention.

Diversity Among a Heterodera glycines Field Isolate and Derived Inbreds Based on RAPD Analysis and Reproduction on Soybean Genotypes

A field population of Heterodera glycines was inbred by a combination of controlled male-female matings and inoculation of soybean with second-stage juveniles (J2) from single cysts. The initial and four F inbred populations were subjected to random amplified polymorphic DNA analysis and were also tested for their ability to reproduce on race differentials. The RAPD patterns of the inbred populations had a lower number of total bands and a lower percentage of polymorphic bands among individual cysts than the initial population. The estimated number of polymorphic loci detected by RAPD analysis was about 25% for the initial population and 4% to 7% for the inbred lines. Reproduction of H. glycines decreased for 6 of 24 inbred-soybean combinations. In particular, reproduction of three inbred populations on PI 90763 was greatly reduced. Inbreeding did not decrease variance of cyst number on soybean genotypes. The inbreeding coefficient calculated from RAPD data was greater than that derived from the known inbreeding pedigree.

The major cell populations of the mouse retina

We report a quantitative analysis of the major populations of cells present in the retina of the C57 mouse. Rod and cone photoreceptors were counted using differential interference contrast microscopy in retinal whole mounts. Horizontal, bipolar, amacrine, and Müller cells were identified in serial section electron micrographs assembled into serial montages. Ganglion cells and displaced amacrine cells were counted by subtracting the number of axons in the optic nerve, learned from electron microscopy, from the total neurons of the ganglion cell layer. The results provide a base of reference for future work on genetically altered animals and put into perspective certain recent studies. Comparable data are now available for the retinas of the rabbit and the monkey. With the exception of the monkey fovea, the inner nuclear layers of the three species contain populations of cells that are, overall, quite similar. This contradicts the previous belief that the retinas of lower mammals are "amacrine-dominated", and therefore more complex, than those of higher mammals.

mtDNA recombination in a natural population

Variation in mtDNA has been used extensively to draw inferences in phylogenetics and population biology. In the majority of eukaryotes investigated, transmission of mtDNA is uniparental and clonal, with genotypic diversity arising from mutation alone. In other eukaryotes, the transmission of mtDNA is biparental or primarily uniparental with the possibility of "leakage" from the minority parent. In these cases, heteroplasmy carries the potential for recombination between mtDNAs of different descent. In fungi, such mtDNA recombination has long been documented but only in laboratory experiments and only under conditions in which heteroplasmy is ensured. Despite this experimental evidence, mtDNA recombination has not been to our knowledge documented in a natural population. Because evidence from natural populations is prerequisite to understanding the evolutionary impact of mtDNA recombination, we investigated the possibility of mtDNA recombination in an organism with the demonstrated potential for heteroplasmy in laboratory matings. Using nucleotide sequence data, we report here that the genotypic structure of mtDNA in a natural population of the basidiomycete fungus Armillaria gallica is inconsistent with purely clonal mtDNA evolution and is fully consistent with mtDNA recombination.

Rhizobium gone native: unexpected plasmid stability of indigenous Rhizobium leguminosarum

Lateral transfer of bacterial plasmids is thought to play an important role in microbial evolution and population dynamics. However, this assumption is based primarily on investigations of medically or agriculturally important bacterial species. To explore the role of lateral transfer in the evolution of bacterial systems not under intensive, human-mediated selection, we examined the association of genotypes at plasmid-encoded and chromosomal loci of native Rhizobium, the nitrogen-fixing symbiont of legumes. To this end, Rhizobium leguminosarum strains nodulating sympatric species of native Trifolium were characterized genetically at plasmid-encoded symbiotic (sym) regions (nodulation AB and nodulation CIJT loci) and a repeated chromosomal locus not involved in the symbiosis with legumes. Restriction fragment length polymorphism analysis was used to distinguish genetic groups at plasmid and chromosomal loci. The correlation between major sym and chromosomal genotypes and the distribution of genotypes across host plant species and sampling location were determined using chi2 analysis. In contrast to findings of previous studies, a strict association existed between major sym plasmid and chromosomal genetic groups, suggesting a lack of successful sym plasmid transfer between major Rhizobium chromosomal types. These data indicate that previous observations of sym plasmid transfer in agricultural settings may seriously overestimate the rates of successful conjugation in systems not impacted by human activities. In addition, a nonrandom distribution of Rhizobium genotypes across host plant species and sampling site demonstrates the importance of both factors in shaping Rhizobium population dynamics.

Population pharmacokinetics of lamotrigine monotherapy in patients with epilepsy: retrospective analysis of routine monitoring data

AIMS

To examine the population pharmacokinetics of lamotrigine in patients newly diagnosed with epilepsy and receiving oral lamotrigine monotherapy for up to 48 weeks.

METHODS

The population consisted of 158 Caucasians and 5 Asians of whom 81 were males and 82 females. Age and weight ranged between 14 and 76 years and 41-107 kg, respectively. A one-compartment compartment model with first-order absorption and elimination was fitted to plasma lamotrigine concentration-time profiles from retrospective drug monitoring, using non-linear mixed effect modelling (NONMEM), with first-order estimation. Oral clearance (CLo), apparent volume of distribution (V/F) and absorption rate constant (Ka) were the main pharmacokinetic parameters.

RESULTS

CLo was not significantly influenced by body weight, age, gender, oral contraceptives and dose. However, due to auto-induction CLo increased by 17.3% during the 48 weeks of therapy, from 1.94 to 2.28 l h(-1), and was 28.7% lower in Asians than Caucasian. The final magnitude in interpatient variability was 32%. The effect of the covariates weight, age, race and gender on V/F was examined and none was statistically significant. The final population estimate of V/F was 77.4 l with an interpatient variability of 34%.

CONCLUSIONS

In view of the wide therapeutic margin of lamotrigine and the 21% residual variability in plasma concentrations, the modest significant effects of race and auto-induction on clearance are unlikely to be clinically significant and, thus, no dosage adjustment is warranted for these effects.

Population Dynamics of Pratylenchus penetrans, Paratylenchus sp., and Criconemella xenoplax on Western Oregon Peppermint

Endoparasitic nematode populations are usually measured separately for soil and roots without a determination of the quantitative relation between soil and root population components. In this study, Pratylenchus penetrans populations in peppermint soil, roots, and rhizomes were expressed as the density within a standardized core consisting of 500 g dry soil plus the roots and rhizomes contained therein. Populations of Paratylenchus sp. and Criconemella xenoplax in 500 g dry soil were also determined, thus measuring the total plant-parasitic nematode population associated with the plant. Mean wet root weight per standard core peaked in spring and again in late summer and was lowest early in the growing season and in early fall. Pratylenchus penetrans populations peaked 4 to 6 weeks after root weight peaks. The percentage of the total population in roots reached 70% to 90% in early April, decreased to 20% to 40% in August, and returned to higher percentages during the winter. Rhizomes never contained more than a minor proportion of the population. Mean Paratylenchus sp. populations increased through spring and peaked in late August. Mean C. xenoplax populations fluctuated, peaking in August or September. Populations of all parasitic species were lowest during winter. Evaluation using the standard core method permits assessment of the total P. penetrans population associated with the plant and of changes in root weight as well as the seasonal distribution of P. penetrans.

Biological Relationship of Meloidogyne hapla Populations to Alfalfa Cultivars

Greenhouse and growth chamber studies were established to determine if there are pathological and physiological differences among Meloidogyne hapla populations from California (CA), Nevada (NV), Utah (UT), and Wyoming (WY) on alfalfa cultivars classified as resistant or susceptible to root-knot nematodes. In the greenhouse, plant survival was not consistent with resistance classifications. While all highly resistant Nevada Synthetic germplasm (Nev Syn XX) plants survived inoculation with all nematode populations, two cultivars classified as moderately resistant ('Chief' and 'Kingstar') survived (P </= 0.05) inoculation with M. hapla populations better than did 'Lobo' cultivar, which is classified as resistant. Plant growth of Nev Syn XX was suppressed by only the CA population, whereas growth of the other alfalfa cultivars classified as M. hapla resistant or moderately resistant was suppressed by all nematode populations. Excluding Nev Syn XX, all alfalfa cultivars were severely galled and susceptible to all nematode populations. Except for Nev Syn XX, reproduction did not differ among the nematode populations on alfalfa cultivars. Nev Syn XX was not as favorable a host to CA as were the other cultivars; but, it was a good host (reproductive factor [Rf] = 37). Temperature affected plant resistance; the UT and WY populations were more pathogenic at 15-25 C, and CA was more pathogenic at 30 C. Nev Syn XX was susceptible to all nematode populations, except for CA, at only 30 C, and all other alfalfa cultivars were susceptible to all nematode populations at all temperatures.

Response of Meloidogyne spp. to Pasteuria penetrans, Fungi, and Cultural Practices in Tobacco

The response of a mixed population of Meloidogyne incognita and M. javanica to three cultural practices, tobacco cultivars (two cultivars, differing in resistance to M. incognita), cover treatments (three treatments), and inorganic nitrogen fertilizer (two treatments), Pasteuria penetrans, and soil-borne fungi was investigated in a tobacco field in 1991. On all sampling dates, higher densities of root-knot nematodes were observed on tobacco cv. Coker 371 Gold than on K-326. Initially, forage sorghum decreased the number of Meloidogyne spp. on tobacco, compared with weeds and hairy indigo, but had little effect on the density of second-stage juveniles (J2) in soil at mid-season or final harvest. The density of P. penetrans endospores also decreased in soil in forage sorghum plots. On one of four sampling dates, high levels of inorganic nitrogen fertilizer increased the number of P. penetrans endospores produced per nematode female, and decreased the density of Meloidogyne spp. on tobacco. The density of P. penetrans endospores increased in these high-N plots after harvest, especially in the plots planted with K-326. The density of J2 in soil was negatively correlated with both the numbers of endospores attached per J2 and the proportion of J2 with attached endospores in midseason soil samples. No correlation was observed between the nematode density and frequency of fungi colonizing the egg masses of Meloidogyne spp.

Effects of Temperature on Pratylenchus neglectus and on Its Pathogenicity to Barley

In a petri-dish study, development of the nematode Pratylenchus neglectus was observed every 4 days, and stage-specific development times were estimated, using a parameter estimation algorithm for a distributed-delay population model. The lower threshold temperature for development of a population of P. neglectus was 7.75 C. Temperatures above 25 C were unfavorable for this population on barley. Total numbers of P. neglectus in barley roots and associated soil in pots were greatest at 25 C and lower at temperatures above and below that level. There was no change in nematode numbers per gram of root as temperature increased between 24 C and 32 C because root weights decreased at higher temperatures. Restricted root mass may contribute to the lower total nematode population levels at higher temperature. Maximum number of nematodes moved through a 2-cm layer of sand on a Baermann funnel at about 20 C; lowest number of nematodes moved at 10 C and 30 C.

Further Details and SEM Observations on Meloidogyne marylandi (Nematoda: Meloidogynidae)

Specimens of Meloidogyne marylandi from Bermuda grass and a population from Zoysia grass were examined and compared morphologically by light and electron microscopy. The populations probably are conspecific and the differences noted in the Zoysia population, mainly those of second-stage juveniles (J2) with shorter tails, are considered normal variations rather than representing another form. Scanning electron microscope observations provided additional details of the perineal pattern and head of females and head and lateral fields of second-stage juveniles. Relationship of M. marylandi to closely related species is given. This species is currently known to occur only in Maryland, and populations previously reported from this state as M. graminis are now considered to be M. marylandi. Other reports of M. graminis in the United States now need to be reconfirmed by examination of voucher or recollected specimens.

Effects of trapping on the vervet (Cercopithecus aethiops sabaeus) population in Barbados

The effects of a 7-year trapping program on a population of vervets, Cercopithecus aethiops sabaeus, in Barbados is described. The pretrapping population was estimated at between 6,000 and 12,000 monkeys. The number trapped annually has increased from less than 200 in 1980 to almost 1,000 in 1986. Despite this, annual catch per trapping effort indicates that population abundance has remained relatively constant. However, the proportion of juveniles to adults in the population has increased markedly, largely because of an increase in the proportion of juvenile females. The data, therefore, suggest that the number of adults in the feral population has been decreasing, while that of juveniles has been increasing. The observation that adults are more vulnerable to trapping than juveniles and the possibility that juvenile survivorship has increased since trapping began may explain these trends. The change in age structure of the population toward juveniles is one explanation for the claimed increase in crop damage in Barbados at constant population size.

Population growth patterns of four species of aphelenchoides on fungi

Qualitative and quantitative differences in population growth patterns of Aphelenchoides rutgersi from Florida, A. sacchari from Jamaica, A. dactylocercus from Great Britain, and A. cibolensis from New Mexico were assessed on 28 species of fungi. The patterns of population growth of A. rutgersi and A. sacchari were statistically similar although not identical, and they differed considerably from those of A. dactylocercus and A. cibolensis. It is suggested that A. rutgersi and A. sacchari, from Florida and Jamaica respectively, may be more closely related to each other than to either A. dactylocercus or A. cibolensis.

Metal substitutions incarbonic anhydrase: a halide ion probe study

Monitoring of the mental health status of the population and assessment of its determinants are 2 of the most relevant pillars of public mental health, and data from population health surveys could be instrumental to support them. Although these surveys could be an important and suitable resource for these purposes, due to different limitations and challenges, they are often relegated to the background behind other data sources, such as electronic health records. These limitations and challenges include those related to measurement properties and cross-cultural validity of the tools used for the assessment of mental disorders, their degree of representativeness, and possible difficulties in the linkage with other data sources. Successfully addressing these limitations could significantly increase the potential of health surveys in the monitoring of mental disorders and ultimately maximize the impact of the relevant policies to reduce their burden at the population level. The widespread use of data from population health surveys, ideally linked to electronic health records data, would enhance the quality of the information available for research, public mental health decision-making, and ultimately addressing the growing burden of mental disorders.

Interactions of Pratylenchus penetrans and Meloidogyne incognita as Coinhabitants in Tomato

Greenhouse experiments on the interactions of Pratylenchus penetrans and Meloidogyne incognita showed that the population densities of both nematode species were depressed whenthey coinhabited tomato roots. Fifty days after inoculation, the population level of a P. penetrans monoculture was about four times higher than when M. incognita was present. Conversely, M. incognita reproduced twice as fast alone as in combination. There were no significant differences in the numbers of P. penetrans when they were inoculated either 10 days prior to or after introduction of M. incognita. Root entry by P. penetrans was significantly inhibited by the presence of M. incognita. Split-root experiments showed that the inhibitory effects of M. incognita upon reproduction of P. penetrans involved factors other than the availability of feeding sites. On the other hand, the inhibitory effects of P. penetrans on M. incognita appeared to be primarily due to the quantity of available roots.