Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 1: Dental and skeletal effects.

This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant.     

Diagnosing menstrual disorders: a qualitative study of the approach of primary care professionals

BACKGROUND: Menstrual disorders are a common presentation in primary care. Wide variations in management as well as discordance between patient and practitioners in relation to presenting problems have been described. AIMS: To explore the model of menstrual disorders used by practitioners in practice. DESIGN OF STUDY: Semi-structured interviews with primary care practitioners. SETTING: One inner London health authority area. METHOD: Constant comparative analysis. RESULTS: Medical practitioners were critical of the guidance provided by gynaecological definitions and texts. Practitioners put more emphasis on defining normality than on defining disorder. Practitioners used a wide range of criteria to judge their patients' complaints and decide on a course of action. Female practitioners had access to personal and professional experience and used this to develop an understanding of women's complaints. Male practitioners in particular were limited by problems in discussing menstruation in detail. Because of the difficulties in assessing patient history, other non-gynaecological factors such as patient age and consulting behaviour informed practitioners' judgements. CONCLUSION: This study draws attention to practitioners' problems in using current definitions of menstrual disorders. The combination of unhelpful medical definitions, lack of standards of normality and difficulties in discussing menstruation resulted in individual practitioners making judgements in idiosyncratic ways. In the absence of a useful gynaecological model, practitioners develop individual, often subjective and gendered models to use in practice.     

In vitro activation of natural killer-like cytotoxicity by specifically in vivo primed T-helper lymphocytes in the rat.

The interaction between the rat non-cytotoxic T lymphocyte subset, which is marked by the W3/25 monoclonal antibody, and natural killer cells was investigated. Specifically in vivo primed lymph node cells were restimulated in vitro with the priming antigen and co-cultured with a source of natural killer cells and their precursors. Cytotoxic activity, generated during a 4 day incubation period, was assessed by lysis of a rat natural killer cell-sensitive tumour target cell line, y3Ag123. This cytotoxic activity was more fully described as natural killer cell cytotoxicity on the basis of target cell specificity, using a range of natural killer cell-susceptible and -resistant targets. The W3/25-positive T cell, separated from the in vivo primed lymph node cells by nylon wool column elution, antibody labelling and sorting on the fluorescence-activated cell sorter, was shown to be necessary to stimulate the generation of this activity. W3/25-negative cells were not active in this respect. The activation was shown to be mediated via lymphokine(s), probably interleukin-2, present in concanavalin A-induced lymphocyte culture supernatants. These supernatants could be used to substitute for in vivo primed, restimulated W3/25-positive lymph node cells in activating natural killer cell cytotoxicity from normal spleen cells. Nylon wool column-eluted spleen cells, activated in vitro with conditioned medium were separated into OX8-positive and OX8-negative subsets using the fluorescence-activated cell sorter. The distribution of cytotoxic activity related to that of freshly derived rat natural killer cells.     

Factors that influence the patient centredness of a consultation.

BACKGROUND. Research suggests that patients are more satisfied with patient-centred consultations than with doctor-centred consultations and that some health measures are positively influenced by this type of consultation. Research on the factors that influence the patient centredness of the consultation is sparse but suggests that women doctors are more patient centred than men doctors. AIM. A study was designed, first, to confirm or reject the suggestion that women general practitioners are more patient centred than men general practitioners and, secondly, to determine some of the factors that might influence the patient centredness of a general practitioner. METHOD. The audiotaped consultations of 41 general practitioners were analysed using an instrument designed to measure patient centredness. The general practitioners were selected from a group of volunteers to represent both sexes as well as a wide range of age and experience. RESULTS. The results of the analysis showed that women general practitioners, particularly trainers, had higher patient-centredness scores than men general practitioners. This behaviour is characterized by an increased frequency of open questions and greater attention to patient offers (anything of potential significance that a patient brings to the general practitioner consultation). Additionally, the combination of sexes in a consultation seemed to have an effect on the interaction, with woman general practitioner/female patient dyads (pairings) having the highest median patient-centredness score, woman general practitioner/male patient and man general practitioner/male patient dyads scoring the same as each other and man general practitioner/female patient dyads having the lowest median scores. CONCLUSION. The results suggest that women general practitioners, in this sample, were more patient centred than men general practitioners. The results also suggest that inherent inequalities exist, with female patients receiving a more patient-centred service from general practitioners of their own sex than from general practitioners of the opposite sex. Male patients, on the other hand, seemed to fare equally well, irrespective of the sex of their general practitioner. Training is required to address these inequalities and to improve the level of patient centredness in the consultation.     

Optic flow signals in extrastriate area MST: comparison of perceptual and neuronal sensitivity

The medial superior temporal area of extrastriate cortex (MST) contains signals selective for nonuniform patterns of motion often termed "optic flow." The presence of such tuning, however, does not necessarily imply involvement in perception. To quantify the relationship between these selective neuronal signals and the perception of optic flow, we designed a discrimination task that allowed us to simultaneously record neuronal and behavioral sensitivities to near-threshold optic flow stimuli tailored to MST cells' preferences. In this two-alternative forced-choice task, we controlled the salience of globally opposite patterns (e.g., expansion and contraction) by varying the coherence of the motion. Using these stimuli, we could both relate the sensitivity of neuronal signals in MST to the animal's behavioral sensitivity and also measure trial-by-trial correlation between neuronal signals and behavioral choices. Neurons in MST showed a wide range of sensitivities to these complex motion stimuli. Many neurons had sensitivities equal or superior to the monkey's threshold. On the other hand, trial-by-trial correlation between neuronal discharge and choice ("choice probability") was weak or nonexistent in our data. Together, these results lead us to conclude that MST contains sufficient information for threshold judgments of optic flow; however, the role of MST activity in optic flow discriminations may be less direct than in other visual motion tasks previously described by other laboratories.     

An improved colorimetric PCR-based method for detection and differentiation of Entamoeba histolytica and Entamoeba dispar in feces.

The epidemiological implications of the recent separation of "Entamoeba histolytica" into two separate species, pathogenic E. histolytica sensu stricto and commensal E. dispar, will not become apparent without methods of distinguishing between them which are applicable to large numbers of specimens. We have modified a PCR-based method to produce such a technique which may be completed in 1 day while still identifying 10(-1) E. histolytica and 1 to 10 E. dispar trophozoites per g of feces when present separately and 10 E. histolytica and 100 E. dispar trophozoites per g in the presence of 10(6) trophozoites per g of the other species. Applied to fecal specimens from 18 patients from which E. histolytica or E. dispar had been grown and identified to the species level by hexokinase isoenzyme analysis, the method in every case yielded the correct result. Positive and negative results are easily distinguished by eye, and we are now applying this technique to a large-scale epidemiological study of amebiasis in the eastern Mediterranean region.     

Estimation of markov chain transition probabilities and rates from fully and partially observed data: uncertainty propagation, evidence synthesis, and model calibration.

Markov transition models are frequently used to model disease progression. The authors show how the solution to Kolmogorov's forward equations can be exploited to map between transition rates and probabilities from probability data in multistate models. They provide a uniform, Bayesian treatment of estimation and propagation of uncertainty of transition rates and probabilities when 1) observations are available on all transitions and exact time at risk in each state (fully observed data) and 2) observations are on initial state and final state after a fixed interval of time but not on the sequence of transitions (partially observed data). The authors show how underlying transition rates can be recovered from partially observed data using Markov chain Monte Carlo methods in WinBUGS, and they suggest diagnostics to investigate inconsistencies between evidence from different starting states. An illustrative example for a 3-state model is given, which shows how the methods extend to more complex Markov models using the software WBDiff to compute solutions. Finally, the authors illustrate how to statistically combine data from multiple sources, including partially observed data at several follow-up times and also how to calibrate a Markov model to be consistent with data from one specific study.