Sampling variability of the Kunst-Mackenbach relative index of inequality.

STUDY OBJECTIVE: To derive methods of calculating confidence limits for the relative index of inequality, defined by Kunst and Mackenbach as a measure of the influence of socioeconomic status on an adverse health index, such as mortality rate. The methods may be used for a health outcome recorded on a continuous scale, as a Poisson count or as a binomial variable. RESULTS AND CONCLUSION: The confidence limits depend on the sampling variability of both the mean mortality rate and the slope of the regression line of mortality on the socioeconomic status scale variable. The best method for a continuous health outcome is based on Fieller's theorem but a good approximation is obtained by substituting the confidence limits for the slope of the regression line into the formula for the calculation of the index, or by using the variance of the logarithmic transform of the index. The last method is the most appropriate for the construction of significance tests comparing indices. The mortality rates may show statistically significant departure from linearity, while not suggesting that a linear relation is inappropriate, and the main decision is whether to base the confidence limits on the conventional standard error of the slope derived from the regression analysis or whether to use the standard deviation of the estimates of mortality rates.

A computerized slot machine simulation to investigate the variables involved in gambling behavior.

The present paper describes a computerized slot machine simulation designed to examine many of the potential variables involved in gambling behavior. This program was created in Visual Basic Version 6.0 and is designed to run on any Windows 95 or higher equipped computer. The program allows for experimenter manipulation of probabilities of payoffs, visual display of potential winning symbols, exact sequences of wins and losses, as well as pose run time questions to the subject on prespecified trials. The program records data on a trial-by-trial basis to a text file for easy importation into many data analysis and statistical programs. Conceptual and experimental questions that may be addressed with the described program are also discussed.

Dextran-70 inhibits equine platelet aggregation induced by PAF but not by other agonists.

Dextrans of mean molecular weight 70 kDa (dextran-70) have had clinical use as anti-thrombotics in man. A major part of the anti-thrombotic action is mediated via inhibition of platelet function. Greatorex (1975, 1977) treated thromboembolic colic in horses with infusions of dextran-70 and reported a 90% recovery rate, but this treatment is nonetheless rarely used. We have used an in vitro method to examine the effect of dextran-70 on equine platelet suspensions, in the hope that understanding the mechanism of action of dextran-70 might lead to the development of alternative therapeutic agents. The effects of dextran-70 on equine platelets occurred immediately in vitro with an initial activation and shape change. Subsequent assessment of aggregation revealed a dose-dependent specific inhibition of platelet-activating factor (PAF)-induced aggregation, significant in rate of aggregation at dextran-70 concentrations >40 g/l (P<0.05) and in extent of aggregation at dextran-70 concentrations >50 g/l (P<0.05). Pre-incubation with 60 g/l dextran-70 significantly inhibited the rate and extent of aggregation in response to PAF (1 nmol/l) (P<0.001 and P = 0.003, respectively) but this was not dependent on the duration of pre-incubation (from 0 to 150 min). No effects were seen when the agonist was adenosine 5'-diphosphate (200 nmol/l), collagen (10 mg/l), 5-hydroxytryptamine (100 micromol/l) or U44069 (600 nmol/l) (all P>0.1). Analysis of PAF concentration-aggregation curves after pre-incubation with 60 g/l dextran-70 indicated significant noncompetitive inhibition by dextran-70 (P<0.001 for rate and extent of aggregation). The ability of dextran-70 to inhibit responses of equine platelets to PAF is probably an important component of its beneficial effect as an anti-thrombotic in colic cases.

Using a self-control training procedure to increase appropriate behavior.

The present study evaluated a technique for teaching self-control and increasing desirable behaviors among adults with developmental disabilities. Results showed that when participants were initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants repeatedly chose the smaller reinforcer. Concurrent fixed-duration/progressive-duration reinforcement schedules then were introduced in which initially both the smaller and larger reinforcers were available immediately. Thereafter, progressively increasing delays were introduced for the schedule associated with the larger reinforcer only. When initial short-duration requirements for access to the larger reinforcer were gradually increased, participants repeatedly selected the larger reinforcer, thereby demonstrating increased self-control.

Engaging in "illusory control" during repeated risk-taking.

Risk-taking behavior occurs when an individual chooses to engage in a game of chance. Although the outcomes of these games are completely random, many individuals believe that they can exercise some control over the outcomes. The present study examined the extent to which five undergraduate roulette players would pay additional money for opportunities to engage in an illusory activity that had no influence on the game's outcome, i.e., choosing random numbers rather than having the experimenter choose them. All five subjects engaged in this type of activity and the extent to which they did was linearly related to the player's winnings. These findings may suggest why people continue to gamble when the odds of winning are against them.

The inhibition of adenylate cyclase in equine platelets by collagen and by platelet-activating factor.

Equine platelet aggregation was stimulated by collagen fibres or platelet-activating factor. The action of both ligands was blocked by forskolin or prostaglandin E(1) agents which are known to activate adenylate cyclase. Equine platelet membranes were found to contain adenylate cyclase activity which was inhibited in dose-dependent fashion by both collagen and platelet-activating factor. Platelet-activating factor-induced inhibition was antagonised by WEB2086.

Extent and kinetics of genetic change in the omp1 gene of Chlamydia trachomatis in two villages with endemic trachoma.

Variants of Chlamydia trachomatis in two Gambian villages with hyperendemic trachoma were analyzed by omp1-based polymerase chain reaction and sequencing from conjunctival swabs. Samples collected over a 22-month period included a complete cross-sectional study of each village. Overall, 4 genovar A and 4 B variants were characterized by point mutations in the omp1 gene, resulting in changes in the inferred amino acid sequence. Two genovar A and 2 B variants accounted for 87% of the total ocular chlamydial infection in both villages. Although some flux in the prevalence of individual variants was observed overtime, their overall distribution remained remarkably stable. There was no evidence of major antigenic shift arising from recombination events at the omp1 locus as described for genital tract infection. These results indicate that omp1 variation in these two trachoma-hyperendemic communities is limited and unlikely to hamper development of trachoma vaccines based on the major outer membrane protein.

A self-capitalization model for building behavior analysis graduate programs.

The development of the Behavior Analysis Program at the University of Nevada through self-capitalization is described. With this model, both doctoral and master's degree programs were established at almost no cost to the university. Some of the problems encountered along the way, including gaining support for the original proposal, attracting and retaining high-quality faculty, engendering support from the Department of Psychology and the university, developing resources, and balancing academic with entrepreneurial demands are discussed, as are the solutions we have found for those problems.

Evidence for naturally occurring recombination in the gene encoding the major outer membrane protein of lymphogranuloma venereum isolates of Chlamydia trachomatis.

The nucleotide sequence of the major outer membrane protein gene (omp1) was determined for three geographically distinct lymphogranuloma venereum isolates which were serologically untypeable. The three omp1 sequences were hybrids of serovars L1 and L2, containing a putative DNA recombination site in variable segment 2. Efforts to manipulate the chlamydial genome in vitro by recombination should be intensified.

The effects of aspirin and paracetamol on the aggregation of equine blood platelets.

The responses of equine blood platelets in citrated platelet-rich plasma to arachidonic acid, U44069 (prostaglandin endoperoxide analogue), adenosine 5'-diphosphate, platelet-activating factor or collagen were investigated by turbidimetric aggregometry. Pre-treatment of the platelets with aspirin (1 mmol/l) or paracetamol (1.3 mmol/l) abolished shape change and aggregation in response to arachidonic acid; decreased the rate of aggregation in response to collagen, with no separate effect on shape change; had no marked effect on aggregation caused by the other agonists; but in no case transformed irreversible aggregation to reversible aggregation. We conclude that thromboxane A2 generation is of minor importance in the aggregation of equine platelets, and in particular that thromboxane A2 is not a significant mediator of irreversible aggregation.

Polymerase chain reaction for the detection of ocular chlamydial infection in trachoma-endemic communities.

Polymerase chain reaction (PCR) with primers derived from the sequence of the cryptic chlamydial plasmid was evaluated for the detection of ocular chlamydial infection in trachoma-endemic populations and was used to explore further the relationship between ocular chlamydial infection and clinical signs of trachoma. It was more sensitive than other laboratory techniques, especially for mild cases of trachoma, in detecting infection in 144 (72%) of 200 who fulfilled the World Health Organization case definition. Of 1132 subjects who did not fulfill these criteria, 85 (7.5%) were PCR-positive, but about one-third of these 85 subjects had minor signs of trachoma. Clinically negative subjects who were PCR-positive were more likely than PCR-negative subjects to have acquired signs of disease at 1 and 6 months of follow-up. Clinical signs were twice as likely to have resolved after 1 month in PCR-negative subjects with disease than in those who were PCR-positive.

Conjunctival scarring in trachoma is associated with depressed cell-mediated immune responses to chlamydial antigens.

In vitro responses of peripheral blood mononuclear cells (PBMC) were measured to antigens of Chlamydia trachomatis in 29 subjects with severe conjunctival scarring and compared with responses from 29 age-, sex-, and location-matched controls from a trachoma-endemic area in The Gambia. Proliferative and interferon-gamma responses were measured against chlamydial elementary bodies, recombinant major outer membrane protein, and affinity-purified recombinant chlamydial heat shock protein 60. Serum antibody levels in response to these antigens were also compared between the two groups, and the presence of ocular chlamydial antigen and DNA was assessed. PBMC from donors with conjunctival scarring had reduced proliferative responses to chlamydial antigens but not control antigens or mitogens compared with matched controls. By contrast, subjects with scarring had significantly higher levels of anti-chlamydial IgG antibody compared with matched controls and were more likely to be harboring ocular chlamydial antigen or DNA (or both).

Longitudinal study of the development of derived relations in an infant.

A normally developing child, Charlie (16 months old at the beginning and 27 months old at the end of this study), was tested several times for the derivation of relations over a period of 8 months. In a series of studies Charlie was: (1) taught to match names to pictures or pictures to names and was tested for derived relations of mutual entailment, (2) tested for retention of trained and derived relations after a 2 week delay and for the derivation of mutual entailment relations after a 1 week delay from training, (3) taught to match sounds to pictures and names to pictures and tested for mutual entailment relations and name-sound and sound-name combinatorial entailment relations, and (4) tested for the matching of a novel picture to a novel name ("nonverbal" exclusion) and for subsequent naming of the novel excluded picture ("verbal" exclusion). The results show that Charlie derived mutual entailment relations and showed nonverbal exclusion as early as 17 months. Combinatorial entailment relations and verbal exclusion emerged later. These findings lend support to the view that derivation of relations is not dependent upon sophisticated verbal abilities, and that such performances can be viewed as historically and contextually situated actions that develop over time.

Genotyping of Chlamydia trachomatis from a trachoma-endemic village in the Gambia by a nested polymerase chain reaction: identification of strain variants.

Direct amplification of the major outer membrane protein (MOMP) gene by polymerase chain reaction (PCR) was used to identify Chlamydia trachomatis in eye swabs from clinically active cases of endemic trachoma in a Gambian village. Chlamydial DNA was detected in 51% of 96 subjects with clinically active disease and in 5% of 37 clinically negative individuals. The PCR detection was combined with typing, using nested primers to variable sequences (VS) 1, 2, and 4 of the MOMP genes to distinguish between trachoma genotypes A, B, and C, respectively. Genotypes A and B were detected in the village, with some individuals harboring both genotypes within the same eye. DNA sequencing revealed strain variants of both genotypes. Typing of genotype and strain variants is now in progress to study trachoma transmission within the village.

The psychological present.

The present paper compares behavior-analytic and cognitive treatments of the concept of psychological history with regard to its role in current action. Both treatments take the position that the past bears some responsibility for the present, and are thereby obligated to find a means of actualizing the past in the present. Both do so by arguing that the past is brought to bear in the present via the organism. Although the arguments of the two positions differ on this issue, neither provides a complete account. An unconventional treatment of psychological history is proposed, the logic of which is exemplified in anthropological, biological, and psychological perspectives. The unconventional treatment in psychological perspective holds that (a) the organism's interaction with its environment, not the organism itself, changes with experience; and (b) the past interactions of an organism exist as, and only as, the present interactions of that organism. This solution to the problem of psychological history provides obligations and opportunities for analysis that are not available when the more conventional positions of cognitivism and behavior analysis are adopted.

The transfer of contextual control over equivalence classes through equivalence classes: a possible model of social stereotyping.

In Experiment 1, subjects acquired conditional equivalence classes controlled by three male and three female names as contextual stimuli. When equivalence relations were tested using new names not used in training (three male and three female), contextual control remained intact. Thus, generalized control of the composition of conditional equivalence classes by characteristically gender-identified names was shown. A basic analysis of this finding was tested in Experiment 2. Contextual equivalence classes were established using as contextual stimuli nonrepresentational visual figures that were members of additional pretrained three-member equivalence classes. When other stimuli in the pretrained equivalence classes were used as contextual stimuli, the conditional equivalence classes remained intact. Control subjects showed that this effect depended on the equivalence relations established in pretraining. The results show that contextual control over equivalence classes can transfer through equivalence classes. The implications of this phenomenon for social stereotyping are discussed.

Chlamydia trachomatis major outer membrane protein epitopes expressed as fusions with LamB in an attenuated aro A strain of Salmonella typhimurium; their application as potential immunogens.

The major outer-membrane protein (MOMP) of Chlamydia trachomatis is the focus of attention for chlamydial vaccine design, particularly those serovar- and subspecies-specific epitopes which provoke neutralizing immune responses. Selected surface-exposed B-cell epitopes of MOMP, incorporating B-subspecies specificities, were expressed as fusions with LamB, an inducible outer-membrane transport protein of Escherichia coli. These recombinant chlamydial-LamB proteins were correctly transported to the outer membrane of both E. coli and an aro A mutant of Salmonella typhimurium. The immunogenicity of the constructs was investigated in a mouse model of chlamydial salpingitis. After oral immunization, recombinant S. typhimurium were recovered from the livers of mice for up to two weeks, and a serum IgG response was induced both to the Salmonella and to the inserted chlamydial epitopes. By contrast, intravenous inoculation was ineffective. Although these LamB fusions proved only weakly immunogenic, this approach should be useful for investigating the ability of attenuated S. typhimurium vaccines incorporating chlamydial epitopes to stimulate protective mucosal immunity in the mouse model of chlamydial salpingitis.

The transfer of specific and general consequential functions through simple and conditional equivalence relations.

The purpose of this study was to examine the transfer of consequential (reinforcement and punishment) functions through equivalence relations. In Experiment 1, 9 subjects acquired three three-member equivalence classes through matching-to-sample training using arbitrary visual forms. Comparison stimuli were then given conditioned reinforcement or punishment functions by pairing them with verbal feedback during a sorting task. For 8 of the 9 subjects, trained consequential functions transferred through their respective equivalence classes without additional training. In Experiment 2, transfer of function was initially tested before equivalence testing per se. Three of 4 subjects showed the transfer without a formal equivalence test. In Experiment 3, 3 subjects were given training that gave rise to six new three-member conditional equivalence classes. For 2 of the subjects, the same stimulus could have either a reinforcement or punishment function on the basis of contextual cues that defined its class membership. Experiment 4 assessed whether equivalence training had established general or specific consequential functions primarily by adding novel stimuli in the transfer test. Subjects treated even novel feedback stimuli in the transfer test as consequences, but the direction of consequential effects depended upon the transfer of specific consequential functions through equivalence relations.