The mycosins of Mycobacterium tuberculosis H37Rv: a family of subtilisin-like serine proteases

There is little information regarding the role of proteolysis in Mycobacterium tuberculosis and no studies on the potential involvement of proteases in the pathogenesis of tuberculosis. We identified five M. tuberculosis genes (mycP1-5) that encode a family of serine proteases (mycosins-1 to 5), ranging from 36 to 47% identity. Each protein contains a catalytic triad (Asp, His, Ser) within highly conserved sequences, typical of proteases of the subtilisin family. These genes are also present in M. bovis BCG and other virulent mycobacteria, but only one homologue (mycP3) was detected in M. smegmatis. The mycosins have N-terminal signal sequences and C-terminal transmembrane anchors, and the localisation of the mycosins to the membrane/cell wall was verified by Western blot analysis of heterologously expressed proteins in cellular fractions of M. smegmatis. In M. tuberculosis, all the mycosins were expressed constitutively during growth in broth. Mycosins-2 and 3 were also expressed constitutively in M. bovis BCG, but no expression of mycosin-1 was detected. Mycosin-2 was modified by cleavage in all three mycobacterial species. The multiplicity and constitutive expression of these proteins suggests that they have an important role in the biology of M. tuberculosis.

Children's serial recall errors: implications for theories of short-term memory development

Three experiments examined developmental changes in serial recall of lists of 6 letters, with errors classified as movements, omissions, intrusions, or repetitions. In Experiments 1 and 2, developmental differences between groups of children aged from 7 to 11 years and adults were found in the pattern of serial recall errors. The errors of older participants were more likely to be movements than were those of younger participants, who made more intrusions and omissions. The number of repetition errors did not change with age, and this finding is interpreted in terms of a developmentally invariant postoutput response inhibition process. This interpretation was supported by the findings of Experiment 3, which measured levels of response inhibition in 7-, 9-, and 11-year-olds by comparing recall of lists with and without repeated items. Response inhibition remained developmentally invariant, although older children showed greater response facilitation (improved correct recall of adjacent repeated items). Group differences in the patterns of other errors are accounted for in terms of developmental changes in levels of output forgetting and changes in the efficiency of temporal encoding processes.

Adult age differences in short-term memory for serial order: data and a model

Age-related deficits in short-term memory have been widely reported, but reduced overall scores could reflect increased order errors, increased omissions, or increased intrusions. Different explanations for reduced short-term memory with aging lead to different predictions. In this study, young (n = 68; M age = 20 years) and older (n = 99; M age = 65 years) adults were presented with lists of letters and were asked to recall each list immediately in the correct order. Age differences in error patterns were similar for auditory and visual presentation. For example, older adults made more errors of every type, and a greater proportion of the older adults' errors were omissions. An additional condition, in which older adults were encouraged to guess, ruled out an age increase in response threshold as a full explanation for the results. The data were modeled by an oscillator-based computational model of memory for serial order. A good fit to the aging data was achieved by simultaneously altering two parameters that were interpreted as corresponding to frontal decline and response slowing.

Improving preventive care by prompting physicians

OBJECTIVES

To assess the impact of prompting physicians on health maintenance, answer questions regarding the mode of delivery, and identify opportunities and limitations of this information intervention.

METHODS

Systematic electronic and manual searches (January 1, 1966, to December 31, 1996) were conducted to identify clinical trial reports on prompting clinicians. Three eligibility criteria were applied: (1) randomized controlled clinical trial, (2) clinician prompt, alert, or reminder in the study group and no similar intervention in the control group, and (3) measurement of the intervention effect on the frequency of preventive care procedures. Data were abstracted by independent reviewers using a standardized abstraction form, and quality of methodology was scored. A series of meta-analyses on triggering clinical actions was performed using the random-effects method. The statistical analyses included 33 eligible studies, which involved 1547 clinicians and 54 693 patients.

RESULTS

Overall, prompting can significantly increase preventive care performance by 13.1% (95% confidence interval [CI], 10.5%-15.6%). However, the effect ranges from 5.8% (95% CI, 1.5%-10.1%) for Papanicolaou smear to 18.3% (95% CI, 11.6%-25.1%) for influenza vaccination. The effect is not cumulative, and the length of intervention period did not show correlation with effect size (R = -0.015, P = .47). Academic affiliation, ratio of residents, and technique of delivery did not have a significant impact on the clinical effect of prompting.

CONCLUSIONS

Dependable performance improvement in preventive care can be accomplished through prompting physicians. Vigorous application of this simple and effective information intervention could save thousands of lives annually. Health care organizations could effectively use prompts, alerts, or reminders to provide information to clinicians when patient care decisions are made.

Oscillator-based memory for serial order

A computational model of human memory for serial order is described (OSCillator-based Associative Recall [OSCAR]). In the model, successive list items become associated to successive states of a dynamic learning-context signal. Retrieval involves reinstatement of the learning context, successive states of which cue successive recalls. The model provides an integrated account of both item memory and order memory and allows the hierarchical representation of temporal order information. The model accounts for a wide range of serial order memory data, including differential item and order memory, transposition gradients, item similarity effects, the effects of item lag and separation in judgments of relative and absolute recency, probed serial recall data, distinctiveness effects, grouping effects at various temporal resolutions, longer term memory for serial order, list length effects, and the effects of vocabulary size on serial recall.

Adult age differences in short-term memory for serial order: data and a model

Age-related deficits in short-term memory have been widely reported, but reduced overall scores could reflect increased order errors, increased omissions, or increased intrusions. Different explanations for reduced short-term memory with aging lead to different predictions. In this study, young (n = 68; M age = 20 years) and older (n = 99; M age = 65 years) adults were presented with lists of letters and were asked to recall each list immediately in the correct order. Age differences in error patterns were similar for auditory and visual presentation. For example, older adults made more errors of every type, and a greater proportion of the older adults' errors were omissions. An additional condition, in which older adults were encouraged to guess, ruled out an age increase in response threshold as a full explanation for the results. The data were modeled by an oscillator-based computational model of memory for serial order. A good fit to the aging data was achieved by simultaneously altering two parameters that were interpreted as corresponding to frontal decline and response slowing.

Community-based survey of maquiladora workers in Tijuana and Tecate, Mexico

Responses to a survey of 177 maquiladora workers by specially trained peers suggest that transnational corporations operating the plants are ignoring Mexican regulations regarding hazard communication, training, health and safety committees, and uncontrolled hazards in the workplace. The "global standard" for workplace health and safety, often claimed by transnationals, should be made a reality.

Developmental changes in time estimation: comparing childhood and old age

Participants from ages 5 to 99 years completed 2 time estimation tasks: a temporal generalization task and a temporal bisection task. Developmental differences in overall levels of performance were found at both ends of the life span and were more marked on the generalization task than the bisection task. Older adults and children performed at lower levels than young adults, but there were also qualitative differences in the patterns of errors made by the older adults and the children. To capture these findings, the authors propose a new developmental model of temporal generalization and bisection. The model assumes developmental changes across the life span in the noisiness of initial perceptual encoding and across childhood in the extent to which long-term memory of time intervals is distorted.

Developmental changes in time estimation: comparing childhood and old age

Participants from ages 5 to 99 years completed 2 time estimation tasks: a temporal generalization task and a temporal bisection task. Developmental differences in overall levels of performance were found at both ends of the life span and were more marked on the generalization task than the bisection task. Older adults and children performed at lower levels than young adults, but there were also qualitative differences in the patterns of errors made by the older adults and the children. To capture these findings, the authors propose a new developmental model of temporal generalization and bisection. The model assumes developmental changes across the life span in the noisiness of initial perceptual encoding and across childhood in the extent to which long-term memory of time intervals is distorted.

Units of analysis in nonword reading: evidence from children and adults

Four experiments examined variations in children's (chronological age range: 5 years 7 months to 9 years 10 months) and adults' reading strategy as a function of task demands. Experiment 1 found that less skilled readers (mean reading age: 8 years 8 months), though able to make use of rime-based spelling-to-sound correspondences (reading "by analogy"), predominantly used simple grapheme-phoneme-level correspondences in reading isolated unfamiliar items. Skilled children (mean reading age: 11 years 6 months) were more likely to adopt an analogy strategy. Experiments 2 and 3 adopted versions of the "clue word" technique used by U. Goswami (1986, Journal of Experimental Child Psychology, 42, 73-83; 1988, Quarterly Journal of Experimental Psychology, 40A, 239-268) and found a much higher incidence of analogical responding by children of all ages, suggesting that reading strategy is task-dependent. Experiment 4 showed that adults' nonword-reading strategy is determined by list composition, in that grapheme-phoneme correspondences are used more when the list context contains nonwords. It is concluded that both adults and young children exhibit considerable flexibility and task-dependence in the levels of spelling-to-sound correspondence (analogies vs decoding) that they use and that grapheme-phoneme correspondences are preferred when maximum generalization to unfamiliar items is required.

Accountability of certified long-term care administrators

To whom and in what ways are administrators and their facilities accountable? This profile of administrators who have completed ACHCA's Professional Certification Program explores how certification increases one's social accountability and improves facility performance.

Muurolane sesquiterpenes from illicium tsangii

A dichloromethane extract of Illicium tsangii has yielded five novel muurolane sesquiterpenes (1, 2, 6, 7, 9) and three new menthane monoterpenes (10-12) in addition to several known compounds. Biogenetic relationships among the sesquiterpenes are discussed.

Scale-invariance as a unifying psychological principle

How can the classical psychological laws be explained and unified? It is proposed here that scale-invariance is a unifying principle. Distributions of many environmental magnitudes are observed to be scale invariant; that is, the statistical structure of the world remains the same at different measurement scales [Mandelbrot, B., 1982. The Fractal Geometry of Nature (2nd Edn.). W.H. Freeman, San Francisco, CA; Bak, P., 1997. How Nature Works: The Science of Self-organized Criticality. Oxford University Press, Oxford, UK]. We hypothesise that the perceptual-motor system reflects and preserves these scale invariances. This allows derivation of several of the most widely applicable psychological laws governing perception and action across domains and species (Weber's, Stevens', Fitts' and Piéron's Laws). We suggest that these fundamental laws reflect accommodation of the perceptuo-motor system to the scale-invariant physical world and therefore have a common foundation.

Operational terminology for stimulus exposure (SE) conditioning

Nomenclature for simple types of learning is ambiguous and incomplete, as even commonly used terms such as 'habituation' and 'sensitization' are not applied consistently. One problem is a failure to distinguish between operational and theoretical constructs linguistically. Operational terminology for reporting behavioural results should be different from the language used in the discussion of learning theory. Thus, systematic operational terminology for simple types of conditioning is proposed. The most general category, stimulus exposure (SE) conditioning, is learning by exposure to a stimulus or to multiple stimuli where explicit inter-stimulus contingencies or instrumental reinforcers are not a part of training. Subtypes of SE conditioning are distinguished by the number of different stimuli used during training, by the method used to assess learning, and by the relationship between training stimuli and the assessment method. These categories include 'alteractive', 'iterative', 'heterostimic', and 'multistimic' conditioning. Learned responses are also categorized as reduction, enhancement, or transformation. SE conditioning categories combine with response terminology in phrases such as 'iterative reduction', which is a decrease in the response to a stimulus due to repeated presentation of that stimulus.

Nonassociative learning processes affecting swimming probability in the seaslug Tritonia diomedea: habituation, sensitization and inhibition

The role of nonassociative learning processes in determining whether or not a chemical stimulus will elicit the Tritonia diomedea swimming response was examined in a variety of conditioning experiments. Iterative presentation of a chemical stimulus resulted in a reduced swimming probability (SP). By the criteria of Thompson and Spencer (Thompson RF, Spencer WA. Psychol. Rev. 1966;73:16-43) and others, this iterative reduction of SP was concluded to be the result of habituation. Site-specificity and a below zero effect implicated sensory pathways in habituation memory storage. The iterative reduction in SP was reversible, confirming that a sensitization-like process can also influence SP. It was further concluded that a short-term decrement in swimming cycle number was most likely due to a constraint in the effector pathway. Experience with a tactile stimulus had a long-lasting decremental effect on SP. This heterostimic reduction of SP was amplified in a multistimic paradigm that included both chemical and tactile stimuli during training. The chemical stimuli alone did not alter SP in this experiment. Multistimic reduction lasted for a week and was reversed temporarily by an excitatory chemical stimulus. The long-lasting reduction of SP by tactile stimulation appears to be the result of a novel nonassociative inhibitory process, which was distinguished from other learning processes by its duration and specificity. A total of three distinct learning processes are postulated to account for the role of simple types of experience in determining SP in Tritonia: habituation, sensitization, and nonassociative inhibition.

Novel method for rapid measurement of growth of mycobacteria in detergent-free media

We describe a novel, rapid, and inexpensive method for the measurement of growth of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium smegmatis in the presence or absence of detergent. The method, which employs hot NaOH treatment of mycobacterial cells to release total cellular protein, compares favorably with other methods for monitoring mycobacterial growth but is particularly useful for heavily clumped cultures grown in defined minimal medium.

Novel phenylpropanoids and lignans from Illicium verum

Nine new phenylpropanoids (2-7, 10, 12, and 14) and two compounds representing novel structural classes of 7-O-8' and 7-O-8'.8-O-7' lignans (8 and 9, respectively) have been isolated from Illicium verum and their structures established by two-dimensional NMR. Most of these compounds appear to be biogenetically derived from threo-anethole glycol: relative stereochemistries for some members of this series were established by NOESY; absolute stereochemistries of others were determined by formation of Mosher esters.

Abietane diterpenes from Illicium angustisepalum

Twelve novel (1, 2, 4, 5, 7-14) and two known (3, 6) abietane diterpenes and have been isolated from the aerial parts of Illicium angustisepalum. These diterpenes are unusual in that they are oxygenated at the axial C-19 position of the gem-dimethyl group rather than the equatorial C-18 position.

The regulation of murine H-2Dd expression by activation transcription factor 1 and cAMP response element binding protein

Resistance to radiation leukemia virus (RadLV)-induced leukemia is correlated with an increase in H-2Dd expression on the thymocyte surface. It has been shown that elevated H-2Dd expression on infected thymocytes is a result of elevated mRNA transcription and that the transcriptional increase is correlated with elevated levels of a DNA binding activity, H-2 binding factor 1 (H-2 BF1), which recognizes the 5'-flanking sequence (5'-TGACGCG-3') of the H-2Dd gene. Recently, it has been shown that the activation transcription factor 1 (ATF-1) homodimer is one form of the H-2 BF1 complex. Here we demonstrate that the cAMP response element binding protein (CREB) homodimer and the heterodimer of CREB/ATF-1 also recognize the cis regulatory motif and are two additional forms of the H-2 BF1 complex. The levels of mRNA encoding ATF-1 and CREB were both increased in RadLV-infected thymocytes that showed increased levels of H-2 mRNA. Also, all three H-2 BF1 binding activities, ATF-1 homodimer, CREB homodimer, and ATF-1/CREB heterodimer, were increased in RadLV-infected thymocytes that expressed high levels of H-2Dd Ag on the cell surface. Transfection experiments demonstrated that ATF-1 and CREB activated a reporter plasmid containing the H-2 BF1 motif. These observations strongly suggest that both ATF-1 and CREB are involved in the regulation of H-2 gene expression following RadLV infection of mouse thymocytes.

Hydroxyapatite cement implant for regeneration of periodontal osseous defects in humans

A newly developed calcium phosphate cement used to promote bone regeneration in craniofacial defects was examined to determine its potential for treatment of periodontal osseous defects. Sixteen patients with moderate to severe periodontal disease and 2 bilaterally similar vertical bony defects received initial therapy including scaling and root planing followed by treatment with either calcium phosphate cement, flap curettage (F/C) or debridement plus demineralized freeze-dried bone allograft (DFDBA). Standardized radiographs were exposed at baseline and 12 months postsurgery for computer assisted densitometric image analysis (CADIA). The extent of the bony defect was determined during initial and 12 month re-entry surgery. Within 6 months of implant placement, 11 of 16 patients treated with calcium phosphate cement exfoliated all or most of the implant through the gingival sulcus. At all 16 test sites, a narrow radiolucent gap formed by 1 month postsurgery at the initially tight visual interface between the radiopaque calcium phosphate cement and the walls of the bony defect. Mean probing depth reduction and clinical attachment gain at sites treated with calcium phosphate cement were 1.6 mm and 1.3 mm, respectively at 1 year. Minimal bony defect fill was accompanied by mean crestal resorption of 1.4 mm. Alveolar crestal resorption at sites with calcium phosphate cement was statistically significant (P=0.001). These findings contrasted with the more favorable outcomes for controls treated with DFDBA or F/C. DFDBA sites exhibited probing depth reduction of 3.1 mm, clinical attachment gain of 2.9 mm, and defect fill of 2.4 mm. Respective clinical changes at F/C sites were 2.4 mm, 1.4 mm, and 1.1 mm. CADIA revealed clinically significant trends between the three treatment modalities at various areas-of-interest. Based on the findings of this study, there is no rationale available to support the use of hydroxyapatite cement implant in its current formulation for the treatment of vertical intrabony periodontal defects.

Tribenzylbutyrolactones and Dibenzyldiphenyl-4,5,6,7-tetrahydrobenzofuranones from Kyrtuthrix maculans

Ten novel compounds, maculalactones B-K (2-11), have been isolated from the marine cyanobacterium Kyrtuthrix maculans. Their structures, which involve either three benzyl groups substituted on a butyrolactone ring or two benzyl and two phenyl groups substituted on a 4,5,6,7-tetrahydrobenzofuranone nucleus, were determined by 2D NMR spectroscopy. Some speculation is made concerning the biogenesis of these two novel classes of natural products.

Isolation and characterisation of an aryl-beta-D-glucoside uptake and utilisation system (abg) from the gram-positive ruminal Clostridium species C. longisporum

A phosphotransferase-dependent aryl-beta-glucoside uptake and utilisation system (abg) was isolated from the ruminal Clostridium ("C. Longisporum"). The system is composed of three genes, abgG, abgF and abgA, and a number of regulatory regions, including terminator/antiterminator type stem-loop structures preceding the abgG and abgF genes. Similarity analysis of the proteins encoded by these genes indicated that they were responsible for the regulation of the abg system through antitermination (AbgG), the uptake and phosphorylation of aryl-beta-glucosides (AbgF) and the hydrolysis of the intracellular phosphorylated glycosides (AbgA). Experimental evidence for the functions of AbgF and AbgA was obtained. Although it was not possible to demonstrate any function for AbgG, a promoter 5' to the abgG gene was identified which was responsible for expression of the downstream genes. The abg system is remarkably similar to operons from the gram negative Enterobacteriaceae, both in the coding and non-coding regulatory regions.

Word-frequency effects on short-term memory tasks: evidence for a redintegration process in immediate serial recall

Four experiments investigated the mechanisms responsible for the advantage enjoyed by high-frequency words in short-term memory tasks. Experiment 1 demonstrated effects of word frequency on memory span that were independent of differences in speech rate. Experiments 2 and 3 showed that word frequency has an increasing effect on serial recall across serial positions, but Experiment 4 showed that this effect was abolished for backward recall. A model that includes a redintegration process that operates to "clean up" decayed short-term memory traces is proposed, and the multinomial processing tree model described by R. Schweickert (1993) is used to provide a quantitative fit to data from Experiments 2, 3, and 4.