Skeletal fluorosis secondary to methoxyflurane use for chronic pain

Skeletal fluorosis is rare and occurs secondary to chronic high amounts of fluoride consumption, manifesting as diffuse osteosclerosis, skeletal pain, connective tissue calcification, and increased fracture risk. Methoxyflurane is a volatile, fluorinated hydrocarbon-inhaled analgesic, and the maximum recommended dose is 15 mL (99.9 % w/w) per wk. A rodent study found increased skeletal fluoride after methoxyflurane exposure. However, skeletal fluorosis secondary to methoxyflurane use in humans has rarely been reported. We present the case of a 47-yr-old female with diffuse osteosclerosis secondary to fluorosis from methoxyflurane use for chronic pain, presenting with 3 yr of generalized bony pain and multiple fragility fractures. Lumbar spine BMD was elevated. CT and radiographs demonstrated new-onset marked diffuse osteosclerosis, with calcification of interosseous membranes and ligaments, and a bone scan demonstrated a grossly increased uptake throughout the skeleton. Biochemistry revealed an elevated alkaline phosphatase and bone turnover markers, mild secondary hyperparathyroidism with vitamin D deficiency, and mild renal impairment. Zoledronic acid, prescribed for presumed Paget's disease, severely exacerbated bony pain. Urinary fluoride was elevated (7.3 mg/L; reference range < 3.0 mg/L) and the patient revealed using methoxyflurane 9 mL per wk for 8 yr for chronic pain. A decalcified bone biopsy revealed haphazardly arranged cement lines and osteocytes lacunae and canaliculi, which was consistent with an osteosclerotic process. Focal subtle basophilic stippling around osteocyte lacunae was suggestive of fluorosis. Although fluorosis is not a histological diagnosis, the presence of compatible histology features was supportive of the diagnosis in this case with clinical-radiological-pathological correlation. Skeletal fluorosis should be considered as a cause of acquired diffuse osteosclerosis. Methoxyflurane should not be recommended for chronic pain. The risk of repeated low-dose exposure to fluoride from methoxyflurane use as analgesia may be greater than expected, and the maximum recommended dose for methoxyflurane may require re-evaluation to minimize skeletal complications.

Abbreviated abstract

Skeletal fluorosis is rare and occurs secondary to chronic high amounts of fluoride consumption, manifesting as diffuse osteosclerosis, skeletal pain, connective tissue calcification, and increased fracture risk. We present the case of a 47-yr-old female with skeletal fluorosis secondary to long-term methoxyflurane for chronic pain. The risk of repeated low-dose exposure to fluoride from methoxyflurane use for analgesia may be greater than expected, and the maximum recommended dose for methoxyflurane may require re-evaluation to minimize skeletal complications.

Rapid assessment of forest canopy and light regime using smartphone hemispherical photography

Hemispherical photography (HP), implemented with cameras equipped with "fisheye" lenses, is a widely used method for describing forest canopies and light regimes. A promising technological advance is the availability of low-cost fisheye lenses for smartphone cameras. However, smartphone camera sensors cannot record a full hemisphere. We investigate whether smartphone HP is a cheaper and faster but still adequate operational alternative to traditional cameras for describing forest canopies and light regimes. We collected hemispherical pictures with both smartphone and traditional cameras in 223 forest sample points, across different overstory species and canopy densities. The smartphone image acquisition followed a faster and simpler protocol than that for the traditional camera. We automatically thresholded all images. We processed the traditional camera images for Canopy Openness (CO) and Site Factor estimation. For smartphone images, we took two pictures with different orientations per point and used two processing protocols: (i) we estimated and averaged total canopy gap from the two single pictures, and (ii) merging the two pictures together, we formed images closer to full hemispheres and estimated from them CO and Site Factors. We compared the same parameters obtained from different cameras and estimated generalized linear mixed models (GLMMs) between them. Total canopy gap estimated from the first processing protocol for smartphone pictures was on average significantly higher than CO estimated from traditional camera images, although with a consistent bias. Canopy Openness and Site Factors estimated from merged smartphone pictures of the second processing protocol were on average significantly higher than those from traditional cameras images, although with relatively little absolute differences and scatter. Smartphone HP is an acceptable alternative to HP using traditional cameras, providing similar results with a faster and cheaper methodology. Smartphone outputs can be directly used as they are for ecological studies, or converted with specific models for a better comparison to traditional cameras.

Perspectives of oncology nurses and oncologists regarding barriers to working with patients from a minority background: Systemic issues and working with interpreters

This study aimed to ascertain the systemic barriers encountered by oncology health professionals (HPs) working with patients from ethnic minorities to guide the development of a communication skills training programme. Twelve medical and five radiation oncologists and 21 oncology nurses were invited to participate in this qualitative study. Participants were interviewed individually or in a focus group about their experiences working with people from minority backgrounds. All interviews were transcribed verbatim and analysed thematically. HPs encountered language and communication barriers in their interactions with patients and their families, which were perceived to impact negatively on the quality and amount of information and support provided. There was a shortage of, and poor processes for engaging, interpreters and some HPs were concerned about the accuracy of interpretation. HPs expressed a need for training in cultural awareness and communication skills with a preference for face-to-face delivery. A lack of funding, a culture of "learning on the job", and time constraints were systemic barriers to training. Oncologists and oncology nurses encounter complex challenges in clinical interactions with minority patients and their families, including difficulties working with interpreters. Formal training programmes targeted to the development of culturally competent communication skills are required.

Changing Patterns of Pertussis in a Children's Hospital in the Polymerase Chain Reaction Diagnostic Era

OBJECTIVE

To assess changes in diagnostic practice and vaccine schedules for pertussis, we used culture-confirmation and clinical severity to compare pertussis cases at a single Australian tertiary pediatric hospital during relevant periods.

STUDY DESIGN

We replicated the case ascertainment methods of a study reporting a 2-year epidemic period 1997-1999 (whole cell pertussis vaccine with 18-month booster, only culture available) to conduct a retrospective cross-sectional observational study over a 6-year period 2007-2012 (acellular pertussis vaccine, no 18-month booster, polymerase chain reaction and culture available). Cases were compared from case note review 2007-2012 (including prevalence of comorbidities) and published data 1997-1999.

RESULTS

During 2007-2012, average annual hospitalizations in those aged < 6 months increased 2.3-fold (32.0 vs 14.0) and in those aged > 6 months by 5.1-fold (17.7 vs 3.5). Limited to culture-positive hospitalizations, there was no increase in those aged < 6 months (14.0 vs 14.5) contrasted with a 4.6-fold increase in those aged > 6 months (2.3 vs 0.5), despite increased annual culture requests (488 vs 188). In 2007-2012, significant comorbidities were documented in 41/72 (57%) hospitalized children aged ≥ 12 months vs 38/225 (17%) <12 months (OR 6.5, 95% CI 3.7-11.7).

CONCLUSIONS

Increased cases of culture-positive hospitalized pertussis were limited to fully immunized children > 6 months of age, consistent with schedule changes. Significant comorbidities were common, making a booster dose at 12-18 months of age especially important.

Choice in transition: A comparison of melioration and the kinetic model

Transition-state choice behavior of pigeons was examined in two experiments designed to test predictions of melioration and the kinetic model. Both experiments began with an initial training condition during which subjects were maintained on concurrent variable-interval schedules. In Experiment 1, subjects were then exposed to concurrent variable-ratio schedules, whereas in Experiment 2, subjects were then exposed to concurrent extinction. Contrary to the predictions of melioration, but consistent with the kinetic model, acquisition of preference on concurrent variable-ratio schedules followed a negatively accelerated logistic trajectory, and preference remained stable in concurrent extinction. Predictions made by the kinetic model concerning rates of switching between alternatives were also supported.

Practical implications of the matching law

Many problem situations in applied settings are best conceptualized as choice situations. In addition, applied behavior analysts create choice situations when they reinforce a competing response to decrease inappropriate behavior. When such situations are analyzed using the matching law, variable interval (VI) schedules of reinforcement prove to be a superior intervention strategy regardless of the nature of the schedule maintaining other, less appropriate behavior. This conclusion is robust in that VI schedule superiority is observed in situations in which choice behavior is highly biased or shows pronounced undermatching as well as those in which the matching law holds precisely. Our analysis demonstrates the potential practical value of mathematical descriptions of behavior.

Lactobacilli and tartrazine as causative agents of red-color spoilage in cucumber pickle products

The cucumber pickling industry has sporadically experienced spoilage outbreaks in pickled cucumber products characterized by development of red color on the surface of the fruits. Lactobacillus casei and Lactobacillus paracasei were isolated from 2 outbreaks of this spoilage that occurred about 15 y apart during the last 3 decades. Both organisms were shown to produce this spoilage when inoculated into pickled cucumbers while concomitantly degrading the azo dye tartrazine (FD&C yellow nr 5). This food dye is used as a yellow coloring in the brine cover solutions of commercial pickled cucumber products. The red color does not occur in the absence of tartrazine, nor when turmeric is used as a yellow coloring in the pickles. Addition of sodium benzoate to the brine cover solutions of a pickled cucumber product, more specifically hamburger dill pickles, prevented growth of these lactic acid bacteria and the development of the red spoilage.

Adenovirus hexon protein enhances nuclear delivery and increases transgene expression of polyethylenimine/plasmid DNA vectors

Inefficient nuclear delivery restricts transgene expression using polyelectrolyte DNA vectors. To increase transfer from the cytoplasm to the nucleus, we have covalently linked adenovirus hexon protein to polyethylenimine (PEI, 800 kDa). Activity of the conjugate was compared with PEI and PEI linked to albumin. Hexon-containing complexes gave 10-fold greater transgene expression in HepG2 cells than PEI/DNA or complexes containing albumin, without increasing cell uptake. Following cytoplasmic injection into Xenopus laevis oocytes, hexon-containing complexes showed reporter gene expression to be elevated by 10-fold compared with PEI/DNA. The ability of hexon to promote nuclear delivery of PEI/DNA nanoparticles was compared with that of classical nuclear localization sequences (NLS) by measuring transgene expression following intracytoplasmic microinjection of hexon-PEI/DNA complexes and NLS-albumin-PEI/DNA complexes in rat-1 fibroblasts. The resulting nuclear transfer efficiency was in the following order: hexon-PEI/DNA>NLS-albumin-PEI/DNA>PEI/DNA>DNA alone>albumin-PEI/DNA. The activities of both NLS-albumin-PEI and hexon-PEI were abolished by co-injection of wheat germ agglutinin, suggesting that both act by means of the nuclear pore complex (NPC); in contrast, excess free NLS-albumin abolished transgene expression with NLS-albumin-PEI/DNA, but only partially inhibited hexon-PEI/DNA. Nuclear transfer efficiency following cytoplasmic injection was dependent on DNA concentration for all materials, although hexon conjugates showed much better activity than NLS-albumin at low DNA doses (500-1000 plasmids/cell). Our data are consistent with hexon mediating nuclear delivery of plasmid complexes by means of the NPC, using mechanisms that are only partially dependent on the classical NLS import pathway. The hexon-mediated mechanism of nuclear import enables substantially better transgene expression, particularly when DNA concentrations in the cytoplasm are limiting.

Percutaneous intervention in saphenous venous grafts: in-stent restenosis lesions are safer than de novo lesions

BACKGROUND

The histological appearance of stenosis in de novo saphenous venous grafts (DNSVG) consists of diffuse atherosclerosis that contains blood elements, necrotic debris and limited fibrocollagenous tissue. The friable nature of these lesions complicates percutaneous intervention (PCI) procedures. On the other hand, in-stent restenosis (ISR) of SVG is due primarily to atherosclerotic plaque or fibromuscular hyperplasia, with thrombus formation playing a secondary role. The purpose of this study is to compare the results of PCI in these two types of SVG lesions.

METHODS

We reviewed our institutional interventional database from March 1996 through February 2000 and identified all consecutive patients who underwent PCI of at least one SVG. One hundred and ten patients were identified: 89 undergoing DNSVG intervention and 21 patients with ISR lesions.

RESULTS

Acute coronary syndromes, degenerated and thrombus-containing lesions were more common in the DNSVG group. "Slow-, no-reflow" complicated 20% of the DNSVG lesions compared to none of the ISR lesions (p = 0.02). Post-procedural myocardial infarction was higher in the DNSVG group (13.5% versus 0%; p = 0.1) and correlated significantly with the occurrence of "slow-, no-reflow" (r = 0.43; p = 0.0001). Utilizing statistical modeling to adjust for baseline differences between the groups, ISR lesions were associated with a low risk of procedural complications (r = 0.22; p = 0.03).

CONCLUSION

This study demonstrates that in this relatively high-risk population, PCI is safer in ISR lesions than in de novo SVG lesions.

Relationships among processing speed, working memory, and fluid intelligence in children

The present review focuses on three issues, (a) the time course of developmental increases in cognitive abilities; (b) the impact of age on individual differences in these abilities, and (c) the mechanisms by which developmental increases in different aspects of cognition affect each other. We conclude from our review of the literature that the development of processing speed, working memory, and fluid intelligence, all follow a similar time course, suggesting that all three abilities develop in concert. Furthermore, the strength of the correlation between speed and intelligence does not appear to change with age, and most of the effect of the age-related increase in speed on intelligence appears to be mediated through the effect of speed on working memory. Finally, most of the effect of the age-related improvement in working memory on intelligence is itself attributable to the effect of the increase in speed on working memory, providing evidence of a cognitive developmental cascade.

Behavioral evidence for brain-based ability factors in visuospatial information processing

The present study examined possible parallels between the structure of human visuospatial abilities and the organization of the neural systems. Forty-eight participants were tested on seven speeded visuospatial tasks. Three of these tasks were constructed so as to rely primarily on known ventral stream functions and four were constructed so as to rely primarily on known dorsal stream functions. Both sets of tasks spanned approximately the same range of difficulty as indexed by both the speed and accuracy of decision making. Factor analysis of response times on the seven tasks revealed only two significant factors. The putative ventral stream tasks all loaded heavily on one factor (mean loading=0.843) but only weakly on the other factor (mean loading=0.222); the putative dorsal stream tasks showed the opposite pattern in that they all loaded heavily on the second factor (mean loading=0.828) but only weakly on the first factor (mean loading=0.229). These findings are consistent with the hypothesis that human visuospatial abilities can be classified using categories based on the specializations of underlying neural structures and systems.

Converging evidence that visuospatial cognition is more age-sensitive than verbal cognition

In 3 separate experiments, the same samples of young and older adults were tested on verbal and visuospatial processing speed tasks, verbal and visuospatial working memory tasks, and verbal and visuospatial paired-associates learning tasks. In Experiment 1, older adults were generally slower than young adults on all speeded tasks, but age-related slowing was much more pronounced on visuospatial tasks than on verbal tasks. In Experiment 2, older adults showed smaller memory spans than young adults in general, but memory for locations showed a greater age difference than memory for letters. In Experiment 3, older adults had greater difficulty learning novel information than young adults overall, but older adults showed greater deficits learning visuospatial than verbal information. Taken together, the differential deficits observed on both speeded and unspeeded tasks strongly suggest that visuospatial cognition is generally more affected by aging than verbal cognition.

Converging evidence that visuospatial cognition is more age-sensitive than verbal cognition

In 3 separate experiments, the same samples of young and older adults were tested on verbal and visuospatial processing speed tasks, verbal and visuospatial working memory tasks, and verbal and visuospatial paired-associates learning tasks. In Experiment 1, older adults were generally slower than young adults on all speeded tasks, but age-related slowing was much more pronounced on visuospatial tasks than on verbal tasks. In Experiment 2, older adults showed smaller memory spans than young adults in general, but memory for locations showed a greater age difference than memory for letters. In Experiment 3, older adults had greater difficulty learning novel information than young adults overall, but older adults showed greater deficits learning visuospatial than verbal information. Taken together, the differential deficits observed on both speeded and unspeeded tasks strongly suggest that visuospatial cognition is generally more affected by aging than verbal cognition.

Age and individual differences in visuospatial processing speed: testing the magnification hypothesis

Forty young adults and 40 older adults performed seven visuospatial information processing tasks. Factor analyses of the response times (RTs) yielded a single principal component with a similar composition in both age samples. For both samples, regressing the mean RTs of fast and slow subgroups for the seven tasks (18 conditions) on the corresponding mean RTs for their age group accounted for 99% of the variance. Taken together, these findings suggest that individual differences in processing time were largely task independent. The magnification hypothesis, a simple mathematical model of the interaction between age and ability, is presented. This model correctly predicts the finding that in both the young and the older adult groups, individual differences increased systematically with task difficulty. The magnification hypothesis also explains the regression parameters describing individual differences among young adults and predicts correctly that equivalent parameters describe individual differences among older adults. According to the magnification hypothesis, the RTs of slower individuals are more affected by aging than those of faster individuals, and slower individuals may be more at risk with respect to other biological insults (e.g., changes in health status) as well.

Selective interference with verbal and spatial working memory in young and older adults

Young and older adults were administered digit and location memory span tasks with and without verbal and spatial secondary tasks. Age differences were greater in location span than in digit span; however, there were no age differences in either the magnitude or pattern of effects of secondary tasks. There were also no age differences in the effects of secondary tasks on a combined (digit and location) task. On the digit and location span tasks, both young and older adults showed only domain-specific interference: naming colors selectively interfered with memory for digits, leaving memory for locations unaffected; pointing to matching colors selectively interfered with memory for locations, leaving memory for digits unimpaired. The results of the present study suggest a greater age deficit in spatial working memory than in verbal working memory, but provide no evidence of an age deficit in susceptibility to interference by secondary tasks in either domain.

Individual and developmental differences in working memory across the life span

The effects of secondary tasks on verbal and spatial working memory were examined in multiple child, young adult, and older adult samples. Although memory span increased with age in the child samples and decreased with age in the adult samples, there was little evidence of systematic change in the magnitude of interference effects. Surprisingly, individuals who had larger memory spans when there was no secondary task showed greater interference effects than their age-mates. These findings are inconsistent with the hypothesis that age and individual differences in working memory are due to differences in the ability to inhibit irrelevant information, at least as this hypothesis is currently formulated. Moreover, our results suggest that different mechanisms underlie developmental and individual differences in susceptibility to interference across the life span. A model is proposed in which memory span and processing speed both increase with development but are relatively independent abilities within age groups.

Cerebellar contribution to linguistic processing efficiency revealed by focal damage

The cerebellum's role in cognitive skills was examined in a child (L.C.) with focal injury to the left cerebellum. Initial symptoms included aphasia and dysarthria. At 3 and 9 months post-injury, clinical neuropsychological tests revealed persistent psychomotor slowing as well as deficits in executive functions. Further cognitive testing at 13 and 16 months post-injury demonstrated that L.C. processed information from both the linguistic and nonlinguistic domains more slowly than age-, grade- and sex-matched controls. Notably, her linguistic processing was more than twice as slow as that of her peers, whereas her nonlinguistic processing was only approximately 20% slower. Within each domain the degree of cognitive slowing was approximately the same across diverse tasks. These results are consistent with the hypothesis of a cerebellar contribution to cognitive processing, particularly the processing of linguistic information.

Short-term and long-term memory in early temporal lobe dysfunction

Following medial temporal damage, mature humans are impaired in retaining new information over long delays but not short delays. The question of whether a similar dissociation occurs in children was addressed by testing children (ages 7-16) with unilateral temporal lobe epilepsy (TLE) and controls on short- and long-term memory tasks, including a spatial delayed response task (SDR). Early-onset TLE did not affect performance on short delays on SDR, but it did impair performance at the longest delay (60 s), similar to adults with unilateral medial temporal damage. In addition, early-onset TLE affected performance on pattern recall, spatial span, and verbal span with rehearsal interference. No differences were found on story recall or on a response inhibition task.

General lexical slowing and the semantic priming effect: the roles of age and ability

Older adults performed three lexical information-processing tasks approximately 1.3 times slower than young adults. Consistent with general lexical slowing, slopes of regressions based on individual subjects' RTs on two of the tasks (single lexical decision and category judgment) did not differ from slopes based on the third (double lexical decision) task. Moreover, slopes based on the single lexical decision and category judgment tasks accurately predicted the size of semantic priming effects on the third (double lexical decision) task. This was true for the older group as a whole, and also for subgroups of fast, medium and slow older adults, as well as for young adult subgroups. The size of the semantic priming effects for the fast old and slow young subgroups (who differed in age but not in processing speed) were approximately equal, consistent with the idea that the effect of age on priming is entirely attributable to slowing. Across all tasks, each old subgroup (fast, medium, or slow) showed the same degree of slowing relative to the corresponding young subgroup, so that the differences in RTs observed between subgroups in the young sample were magnified in the old sample. Taken together, the present findings suggest that ability-related differences in lexical processing speed may be functionally equivalent to age-related differences and that both factors interact to determine performance on speeded lexical tasks.

Verbal and spatial working memory in school-age children: developmental differences in susceptibility to interference

The development of verbal and spatial working memory was investigated with an interference paradigm. Memory spans were obtained from 3 groups (8-, 10-, and 19-year-olds) under 6 different conditions: Two primary memory tasks (1 verbal, 1 spatial) were administered in isolation and in conjunction with 2 versions of a secondary task. The primary tasks required recalling a series of visually presented digits and recalling the locations of Xs in a series of visually presented grids. The secondary tasks required reporting the color of the stimuli as they were presented using either a verbal or a spatial response. Analyses revealed that all age groups showed domain-specific interference (i.e., interference by a secondary task from the same domain as the primary task), but only the 8-year-olds also showed nonspecific interference (i.e., interference by a secondary task from a domain different than the primary memory task), suggesting that at least some executive functions do not reach adult levels of efficiency until approximately age 10.

Verbal and spatial working memory in school-age children: developmental differences in susceptibility to interference

The development of verbal and spatial working memory was investigated with an interference paradigm. Memory spans were obtained from 3 groups (8-, 10-, and 19-year-olds) under 6 different conditions: Two primary memory tasks (1 verbal, 1 spatial) were administered in isolation and in conjunction with 2 versions of a secondary task. The primary tasks required recalling a series of visually presented digits and recalling the locations of Xs in a series of visually presented grids. The secondary tasks required reporting the color of the stimuli as they were presented using either a verbal or a spatial response. Analyses revealed that all age groups showed domain-specific interference (i.e., interference by a secondary task from the same domain as the primary task), but only the 8-year-olds also showed nonspecific interference (i.e., interference by a secondary task from a domain different than the primary memory task), suggesting that at least some executive functions do not reach adult levels of efficiency until approximately age 10.

A novel biologic function of serum amyloid A. Induction of T lymphocyte migration and adhesion

In the course of an inflammatory response, the concentration of serum amyloid A (SAA), a hepatocyte-derived acute phase protein, increases up to 1000-fold above the normal level. Although SAA was previously thought to be immunosuppressive, we recently reported that SAA is a potent chemoattractant for monocytes and neutrophils. The present study shows that recombinant human (rh) SAA also induces directional migration of T cells in vitro. Phenotypic analyses revealed that CD4+ and CD8+ T cell subsets were equally responsive to rhSAA, whereas CD45RA cells were also not selectively attracted by rhSAA. The T cell chemotaxis induced by rhSAA was inhibited by pretreatment of cells with pertussis toxin, suggesting the interaction of rhSAA with a G-protein-coupled receptor species. T cells pretreated with an optimal concentration of SAA exhibited enhanced adherence to human umbilical cord endothelial cell monolayers. Subcutaneous administration of rhSAA into huPBL-SCID mice caused the infiltration of human T lymphocytes at the injection sites by 4 h. These results suggest that SAA may play an important role in recruiting T lymphocytes, as well as neutrophils and monocytes into inflammatory lesions.

A novel biologic function of serum amyloid A. Induction of T lymphocyte migration and adhesion

In the course of an inflammatory response, the concentration of serum amyloid A (SAA), a hepatocyte-derived acute phase protein, increases up to 1000-fold above the normal level. Although SAA was previously thought to be immunosuppressive, we recently reported that SAA is a potent chemoattractant for monocytes and neutrophils. The present study shows that recombinant human (rh) SAA also induces directional migration of T cells in vitro. Phenotypic analyses revealed that CD4+ and CD8+ T cell subsets were equally responsive to rhSAA, whereas CD45RA cells were also not selectively attracted by rhSAA. The T cell chemotaxis induced by rhSAA was inhibited by pretreatment of cells with pertussis toxin, suggesting the interaction of rhSAA with a G-protein-coupled receptor species. T cells pretreated with an optimal concentration of SAA exhibited enhanced adherence to human umbilical cord endothelial cell monolayers. Subcutaneous administration of rhSAA into huPBL-SCID mice caused the infiltration of human T lymphocytes at the injection sites by 4 h. These results suggest that SAA may play an important role in recruiting T lymphocytes, as well as neutrophils and monocytes into inflammatory lesions.

Converging evidence for domain-specific slowing from multiple nonlexical tasks and multiple analytic methods

Older and young adults were tested on eight nonlexical tasks that overlapped extensively in complexity: disjunctive choice reaction time, line-length discrimination, letter classification, shape classification, mental rotation, visual search, abstract matching, and mental paper-folding. Performance on the first seven tasks was associated with equivalently low error rates in both groups, making it possible to directly compare their response times (RTs) on these tasks. Consistent with domain-specific slowing, the relationship between the RTs of the older adults and the RTs of the young adults was well described by a task-independent mathematical (Brinley) function. Evidence from this analysis and from analyses based on task-specific information-processing models leads to similar conclusions and provides converging support for general cognitive slowing in the nonlexical domain.

Preconditioning stimuli and inadvertent preconditioning

There are several factors besides brief episodes of total coronary occlusion which can provide sufficient stress to result in a preconditioning-like effect on the size of a myocardial infarction. Partial coronary artery stenosis, hypoxia, stretch, catecholamines, rapid pacing, and certain pharmacologic therapies may provide preconditioning stimuli. These same factors as well as mechanical complications in which a coronary artery is briefly occluded or stenosed prior to a subsequent coronary occlusion may lead to inadvertent preconditioning and confound the results of experimental cardiology studies.

Working memory following improvements in articulation rate in children with cerebral palsy

It has been postulated that rehearsal rate is the primary determinant of working memory capacity for verbal material (Baddeley et al., 1975). A previous study of normal control children and children with spastic diplegic cerebral palsy (SDCP) suggested that covert rather than overt rehearsal rate determines working memory capacity (White et al., 1994). In the current study, a subset of SDCP children who received a surgical treatment to relieve spasticity were retested on measures of articulation rate and memory span. A subset of control children from the original study were also retested. The SDCP group showed improvements in articulation rate at follow-up, though memory span did not change and was again equivalent to that of controls. These findings indicate that increases in articulation rate are not necessarily accompanied by improvements in memory span, and provide additional evidence that working memory capacity may be determined by covert rather than overt articulatory rehearsal.

The rise and fall in information-processing rates over the life span

We surveyed studies that measured information-processing durations in groups of experimental subjects (children or elderly adults) and a group of college-aged control subjects. Some studies varied the type of processing while keeping the age of a subject group fixed. Process-durations in experimental subjects could be described by a multiplicative function of the control durations, regardless of the type of processing. Other studies varied the age of the subject groups while keeping the type of processing fixed. Process-durations declined during childhood, in a manner that could be described by a negative exponential function of age. Process-durations increased throughout middle- and old-age, in a manner that could be described by a positive exponential function of age. The sum of the two exponentials defined a U-shaped function that described process-durations over the life span. The most important studies varied both the type of processing and the age of the subject groups. An array of measurements of this kind could be described by a two-dimensional function that combined the multiplicative effect of process-duration and the exponential effects of age. The multiplicative effect of process-duration suggested that the execution of a processing sequence was conditioned by a single developmental parameter in both the experimental subject and the control subject. The exponential components determined the magnitude of the developmental parameter as the age of the subject changed. Given the global character of these effects, it seemed to us that the developmental mechanism may operate at a more elementary level than the information-processing stages conceived by cognitive theories. In a developmental framework, information processing may be reducible to a large number of small steps of a homogeneous duration or reliability, such as might be realized on a neural network. The exponential rate constants may be related to constant-probability hazards that act on one or another population of neural elements to create minute defects or incremental improvements. Their cumulative effects alter the functioning of the network over its lifetime, in a way that parallels the observed changes in process-durations.

Brinley plots, explained variance, and the analysis of age differences in response latencies

Critics of Brinley plot analyses (e.g., Fisk, Fisher, & Rogers, 1992; Perfect, 1994) claim: (a) that lack of overlap between latencies on different tasks inflates r2 values; (b) that Brinley plots mask task-specific age differences; and (c) that measurement error in young adults' latencies precludes the use of regression techniques with Brinley plot data. We dispute these claims. We show that lack of overlap does not inflate r2 and that the possible presence of task-specific effects in Brinley plot data may be evaluated using standard regression techniques. These techniques are illustrated using data from the Fisk and Rogers (1991) study of visual and memory search. Analysis of their data reveals significant differences between the lexical and nonlexical domains, but not between types of search. Finally, the effect of measurement error on Brinley plot analyses is shown to be small and, if taken into account, leads to increased support for general cognitive slowing.

Cardiovascular applications of fluorocarbons in regional ischemia/reperfusion

Potential cardiovascular therapeutic uses for perfluorochemicals include oxygen delivery distal to an occluding balloon during high risk coronary angioplasties, treatment for acute myocardial infarction with or without concomitant reperfusion, cardioplegia, and preservation of donor hearts for transplant. Infusions of oxygenated perfluorochemicals during brief coronary occlusions, as occurs with angioplasties, preserves cardiac ultrastructure and cardiac function. Fluosol is currently approved in the U.S. for angioplasty procedures. Experimental studies have suggested that perfluorochemicals reduce myocardial infarct size during permanent coronary occlusion or temporary coronary occlusion. One school of thought suggests that these agents work by reducing reperfusion injury. By inhibiting neutrophil function, including adherence to endothelial cells and release of toxic substances, perfluorochemicals may preserve the endothelium and prevent no-reflow. However, one might argue that any agent which reduces infarct size by any mechanism would result in less neutrophil infiltration and smaller no-reflow areas. One pilot study suggested that intracoronary Fluosol administered at the time of reperfusion, reduced infarct size and improved regional ventricular function in patients. However, preliminary results of a large multicenter study in which this agent was given along with thrombolysis, were largely negative. Whether perfluorochemicals will become an important adjunctive agent along with reperfusion for acute myocardial infarction remains to be determined.

Purification and immunological characterization of acid beta-galactosidase from dog liver

1. Dog liver acid beta-galactosidase was isolated in high yield and purified to homogeneity using a series of chromatographies on Con A-Sepharose, decyl-agarose, anion-exchange HPLC and gel-filtration HPLC. 2. Non-denaturing gel filtration by HPLC gave a single homogeneous peak corresponding to molecular mass of 180-190 kDa. During SDS-PAGE analysis, the single peak dissociated into a major band corresponding to molecular mass of 32 kDa with minor bands at 18 and 13 kDa. 3. Polyclonal antibodies raised against the purified enzyme immunoprecipitated beta-galactosidase activity specifically from dog liver extracts and recognized a single 32 kDa band in Western blot analysis of dog tissue homogenates. This antibody did not crossreact with any protein band in tissue homogenates from other species examined except cat. 4. Western blot analysis of tissue extracts from dogs affected with GM1-gangliosidosis showed the presence of a 32 kDa band similar to that of controls.

The results of efforts to improve compliance with supportive periodontal treatment in a private practice

Patients who receive routine supportive periodontal treatment (SPT) tend to keep their teeth longer and enjoy greater periodontal health than those individual who do not receive this therapy. Previous studies have found less than optimal compliance to suggested SPT. The study reported in this paper covered 5 years of patient data and measured the effects of efforts to improve compliance in a private periodontal practice. These efforts included attempts at simplifying compliance, maintaining records of compliance, informing patients of the consequences of noncompliance, and attempting to identify noncompliers before active periodontal therapy was initiated. The results were measured against a similar group studied in previous work within the same office published in 1984. The main finding of the present study was an increase in complete compliance from 16% in 1984 to 32% in 1991. This increase came largely at the expense of the noncompliant group. The reason for the increase in compliance is likely due to efforts to increase compliance carried out in the office. However, other factors such as change in the hygiene practice law, increased public awareness of dental needs, and economic depression may also have affected compliance. This information suggests that noncompliance can be reduced if the problem is recognized and efforts are made to increase compliance.

Flow-function dissociation following an acute dose of cocaine: effect of captopril on coronary flow

BACKGROUND

Acute administration of cocaine leads to left ventricular dysfunction and a decrease in coronary blood flow. This experiment studied the relationship between function and flow over time in cocaine heart disease and examined the effects of captopril on this relationship.

METHODS

Dogs anesthetized with pentobarbital (n = 13) were given a 3 mg/kg body weight intravenous bolus of cocaine followed by a 7 mg/kg infusion over 10 minutes. Animals were then randomly assigned to receive either captopril (0.5 mg/kg infused over 5 minutes, followed by 0.5 mg/kg/h) or an equivalent volume of saline beginning 15 minutes after cocaine administration. Coronary blood flow (radioactive microspheres and Doppler flow probes) and left ventricular function (two-dimensional echocardiogram and dP/dt) were monitored for 2 hours.

RESULTS

Within 15 minutes, cocaine caused a drop in dP/dt by 39% to 42% and in coronary blood flow by 35%. Cocaine also caused an increase in left ventricular end-diastolic pressures in both groups. Cocaine resulted in prolongation of an index of end-diastolic isovolumic relaxation time (tau) from a baseline of 34 milliseconds to 56 milliseconds at 15 minutes after cocaine administration in the control group and from a baseline of 35 milliseconds to 49 milliseconds in the captopril group (P < 0.05). By 2 hours after therapy, the tau in the control group remained elevated, whereas in the captopril group it returned toward baseline. At 2 hours of observation, systolic function recovered while coronary flow remained depressed. There was no difference between the captopril and control groups in coronary blood flow or systolic cardiac function at any time during the study.

CONCLUSIONS

Cocaine caused left ventricular systolic and diastolic dysfunction as well as reduced coronary blood flow. At 2 hours there is a dissociation of systolic function, which recovers, and of coronary blood flow, which does not. Captopril had no effect on coronary blood flow or systolic left ventricular function following cocaine administration.

The effects of acute and chronic cocaine use on the heart

It is clear that cocaine has cardiotoxic effects. Acute doses of cocaine suppress myocardial contractility, reduce coronary caliber and coronary blood flow, induce electrical abnormalities in the heart, and in conscious preparations increase heart rate and blood pressure. These effects will decrease myocardial oxygen supply and may increase demand (if heart rate and blood pressure rise). Thus, myocardial ischemia and/or infarction may occur, the latter leading to large areas of confluent necrosis. Increased platelet aggregability may contribute to ischemia and/or infarction. Young patients who present with acute myocardial infarction, especially without other risk factors, should be questioned regarding use of cocaine. As recently pointed out by Cregler, cocaine is a new and sometimes unrecognized risk factor for heart disease. Acute depression of LV function by cocaine may lead to the presence of a transient cardiomyopathic presentation. Chronic cocaine use can lead to the above problems as well as to acceleration of atherosclerosis. Direct toxic effects on the myocardium have been suggested, including scattered foci of myocyte necrosis (and in some but not all studies, contraction band necrosis), myocarditis, and foci of myocyte fibrosis. These abnormalities may lead to cases of cardiomyopathy. Left ventricular hypertrophy associated with chronic cocaine recently has been described. Arrhythmias and sudden death may be observed in acute or chronic use of cocaine. Miscellaneous cardiovascular abnormalities include ruptured aorta and endocarditis. Most of the cardiac toxicity with cocaine can be traced to two basic mechanisms: one is its ability to block sodium channels, leading to a local anesthetic or membrane-stabilizing effect; the second is its ability to block reuptake of catecholamines in the presynaptic neurons in the central and peripheral nervous system, resulting in increased sympathetic output and increased catecholamines. Other potential mechanisms of cocaine cardiotoxicity include a possible direct calcium effect leading to contraction of vessels and contraction bands in myocytes, hypersensitivity, and increased platelet aggregation (which may be related to increased catecholamine). The correct therapy for cocaine cardiotoxicity is not known. Calcium blockers, alpha-blockers, nitrates, and thrombolytic therapy show some promise for acute toxicity. Beta-Blockade is controversial and may worsen coronary blood flow. In patients who develop cardiomyopathy, the usual therapy for this entity is appropriate.

General slowing in semantic priming and word recognition

Analyses of lexical decision studies revealed that (a) older (O) adults' mean semantic priming effect was 1.44 times that of younger (Y) adults, (b) regression lines describing the relations between older and younger adults' latencies in related (O = 1.54 Y-112 and unrelated conditions (O = 1.50 Y-93) were not significantly different, and (c) that there was a proportional relation between older and younger adults' priming effects (O = 1.48 Y-2). Analyses of word-naming studies yielded similar results. Analyses of delayed pronunciation data (Balota & Duchek, 1988) revealed that word recognition was 1.47 times slower in older adults, whereas older adults' output processes were only 1.26 times slower. Overall, analyses of whole latencies and durations of component processes provide converging evidence for a general slowing factor of approximately 1.5 for lexical information processing.