On the sins of short-form development

The empirical short-form literature has been characterized by overly optimistic views of the transfer of validity from parent form to short form and by the weak application of psychometric principles in validating short forms. Reviewers have thus opposed constructing short forms altogether, implying researchers are succumbing to an inappropriate temptation by trying to abbreviate measures. The authors disagree. The authors do not oppose the development of short forms, but they do assert that the validity standards for short forms should be quite high. The authors identify 2 general and 9 specific methodological sins characterizing short-form construction and offer methodological suggestions for the sound development of short forms. They recommend a set of 6 a priori steps researchers should consider and 9 methodological procedures researchers can use to develop valid abbreviated forms of clinical-assessment procedures.

Formulating clinical research hypotheses as structural equation models: a conceptual overview

Structural equation modeling is a comprehensive, flexible approach to research design and data analysis. Although in recent years there has been phenomenal growth in the literature on technical aspects of structural equation modeling, relatively little attention has been devoted to conceiving research hypotheses as structural equation models. The aim of this article is to provide a conceptual overview of clinical research hypotheses that invite evaluation as structural equation models. Particular attention is devoted to hypotheses that are not adequately evaluated using traditional statistical models.

Using alcohol expectancies to predict adolescent drinking behavior after one year

An accumulating literature has shown the influence of childhood experiences associated with alcohol use on later drinking practices. Recent studies have suggested that alcohol-related expectancy may serve as an intervening variable to connect these early experiences with the later, proximal decision to drink when opportunities for actual alcohol consumption arise. Those studies, however, have collected expectancy and drinking data concurrently, whereas the present study for the first time reports on the power of expectancies measured in early adolescents (seventh and eighth grades) to predict self-reported drinking onset and drinking behavior measured a full year later. Results show that five of seven expectancy scores readily discriminated between nonproblem drinkers and those subsequently beginning problem drinking and accounted for a large portion of the variance in a continuous quantity/frequency index and a problem drinking index. The strength of these timelagged relations strengthens the case for inferring that expectancies have causal power on drinking behavior and suggests prevention strategies.

Expectancy for social facilitation from drinking: the divergent paths of high-expectancy and low-expectancy adolescents

Using a 3-wave longitudinal design, adolescents were studied over a 2-year period during which many first began to drink. Covariance structure modeling showed that teens' expectancy for social facilitation from alcohol and their drinking experience influenced each other in a reciprocal, positive feedback fashion: the greater the expectancy endorsement, the higher subsequent drinking levels, and the higher the drinking levels, the greater the subsequent expectancy endorsement. This model fit the data quite well; comparison models, in which expectancy (or drinking) had no independent influence on future drinking (or expectancy), showed significantly poorer fit than the present model. Initial nondrinkers' social expectancy predicted individual differences in the rate of drinking increase over the 2 years. Results bolster the hypothesis that expectancy actively influences drinking and point to the importance of expectancy-based intervention efforts.

Alcoholism and memory: broadening the scope of alcohol-expectancy research

Current biopsychosocial research on the etiology of alcoholism has begun to focus on memory processes as a possible common pathway for drinking decisions. The alcohol-expectancy construct is rooted both in cognitive psychology and alcohol research and can serve as a vehicle for this study. Reexamination of one recent review of issues in alcohol-expectancy research provides an opportunity to broaden the scope of this research with theoretical and methodological alternatives to those suggested in that review. Most importantly, this article shows that expectancy findings, discussed by Leigh (1989a) as reflecting "psychometric" limitations, are instead quite consistent with recent network models of memory structure. Such models can provide an informative guide to future research activities. It is also recommended that alcohol-expectancy research remain open to inputs from expectancy theories already developed in several psychological domains, as well as to theories of social cognition and attitude structure in addition to those advanced by Leigh.

Self-reported drinking and alcohol-related problems among early adolescents: dimensionality and validity over 24 months

OBJECTIVE

Researchers rely on adolescents' self-reports of alcohol consumption and alcohol-related problems, despite little evidence concerning their validity. We assessed the reliability and validity of adolescents' self-reports, employing collateral validation and focusing on the understudied transitional years of early adolescence.

METHOD

Subjects were 214 boys and 247 girls who participated in school-wide surveys that assessed drinking, drunkenness and alcohol-related problems each year for 3 years. These measures were validated by collateral (peer) reports and by separate, 7-day drinking calenders. Internal consistency and test-retest reliability were also assessed.

RESULTS

Results replicated findings with older adolescents that drinking/drunkenness and alcohol-related problems fall on two partially overlapping dimensions. Scales assessing each dimension had moderate to high internal consistency and high test-retest stability. Correlations with collateral reports were relatively strong for the drinking/drunkenness scale, moderate for a dichotomous variable reflecting the presence or absence of alcohol-related problems, and more modest for the alcohol-related problems scale. Correlations with diary reports of drinking behavior were strong for drinking/drunkenness. Results generally replicated across gender and over time.

CONCLUSIONS

Researchers can have some confidence in the reliability and validity of early adolescents' survey self-reports, particularly of alcohol consumption (alcohol-related problems occurred with low base rates, perhaps limiting validity coefficients). Because drinking/drunkenness and alcohol-related problems shared 30% of their variance, factors other than consumption (e.g., personality factors) apparently influenced the experience of alcohol-related problems.

Emergence of alcohol expectancies in childhood: a possible critical period

Previous investigations with adolescents (aged 12-19) have shown alcohol-related expectancies to develop in childhood prior to significant drinking experience and to covary directly with drinking behavior. To chart the development of alcohol expectancies in children as young as age 6, a procedure was developed to be as independent as possible of age-related variation in reading and language development. This instrument was administered to 114 elementary school children of both genders, distributed across grades 1 to 5. Psychometric analysis provided evidence of the test's reliability and validity. Evaluation of the developmental pattern produced two primary findings: (1) there was an overall trend of increasingly positive expectancies with age; and (2) strikingly, the bulk of the increase was observed in the third and fourth grades. Children's expectancies may be less differentiated than adolescent or adult expectancies. These findings suggest that the precursors for later alcohol use and abuse are formed in childhood and that prevention efforts may need to begin as early as third grade.

On the sins of short-form development

The empirical short-form literature has been characterized by overly optimistic views of the transfer of validity from parent form to short form and by the weak application of psychometric principles in validating short forms. Reviewers have thus opposed constructing short forms altogether, implying researchers are succumbing to an inappropriate temptation by trying to abbreviate measures. The authors disagree. The authors do not oppose the development of short forms, but they do assert that the validity standards for short forms should be quite high. The authors identify 2 general and 9 specific methodological sins characterizing short-form construction and offer methodological suggestions for the sound development of short forms. They recommend a set of 6 a priori steps researchers should consider and 9 methodological procedures researchers can use to develop valid abbreviated forms of clinical-assessment procedures.

13N ammonia myocardial imaging at rest and with exercise in normal volunteers. Quantification of absolute myocardial perfusion with dynamic positron emission tomography

Positron emission tomography (PET) was applied to the measurement of myocardial perfusion using the perfusion tracer 13N-labeled ammonia. 13N ammonia was delivered intravenously to 13 healthy volunteers both at rest and during supine bicycle exercise. Dynamic PET imaging was obtained in three cross-sectional planes for 10 minutes commencing with each injection. The left ventricle was divided into eight sectors, and a small region of interest was assigned to the left ventricular blood pool to obtain the arterial input function. The net extraction of 13N ammonia was obtained for each sector by dividing the tissue 13N concentration at 10 minutes by the integral of the input function from the time of injection to 10 minutes. With this approach for calculating net extractions, rest and exercise net extractions were not significantly different from each other. To obviate possible overestimation of the true 13N ammonia input function by contamination by 13N-labeled compounds other than 13N ammonia or by spillover from myocardium into blood pool, the net extractions were calculated using only the first 90 seconds of the blood and tissue time-activity curves. This approach for calculating net extractions yielded significant differences between rest and exercise, with an average ratio of exercise to rest of 1.38 +/- 0.34. Nonetheless, the increase was less than predicted from the average 2.7-2.8-fold increase in double product at peak exercise or the 1.7-fold increase in double product at 1 minute after exercise. However, when the first 90 seconds of dynamic data were fit with a two compartment tracer kinetic model, average perfusion rates of 0.75 +/- 0.43 ml/min/g at rest and 1.50 +/- 0.74 ml/min/g with exercise were obtained. This average increase in perfusion of 2.2-fold corresponded to similar average increases in double product. Thus, the noninvasive technique of PET imaging with 13N ammonia shows promise for future applications in determining absolute flows in patients with coronary artery disease.

Seasonal changes in song nuclei and song behavior in Gambel's white-crowned sparrows

In males of several songbird species, the morphology of forebrain nuclei that control song changes seasonally. The only seasonally breeding songbird in which seasonal changes in the structure of song control nuclei have been reported not to occur is the nonmigratory Nuttall's subspecies of white-crowned sparrow. In the present study, we manipulated photoperiod and plasma testosterone concentrations in captive male white-crowned sparrows of the migratory Gambel's subspecies. Males exposed to photoperiods and plasma testosterone concentrations typical of those experienced by wild breeding males had larger song control nuclei than males held on a winter photoperiod. We also found seasonal changes in stereotype of spectral and temporal parameters of song in wild Gambel's white-crowned sparrows. We hypothesize that seasonal changes in the song control nuclei may correlate with seasonal changes in song stereotypy.

The availability and dimensions of tree hollows that provide nest sites for cockatoos (Psittaciformes) in Western Australia

A 15-ha plot of salmon gum woodland contained 241 hollows with an entrance diameter and depth exceeding 90 mm, in 173 trees, the majority (95%) in salmon gums. Occupancy of these hollows during the spring of 1978 was 47%; eight species of bird (six Psittaciformes, one Anseriformes and one Falconiformes) were involved. Galahs, corellas, red-tailed black cockatoos and Port Lincoln parrots were the most numerous hollow-nesting birds in the area; there were differences in the sizes of hollows they used, which were separable on entrance size and on inside diameter of the hollow 0.5 m below the entrance. There was a trend for hollow size to decrease in the order: red-tailed black cockatoos, corellas, galahs and Port Lincoln parrots. Red-tailed black cockatoos nested in more dead trees, or trees which were lower and had smaller canopies, than did the other three species. The woodland contained few young trees, trees were dying rapidly and there was no regeneration. This situation is typical for woodland throughout the agricultural area, and future prospects are discussed.

Roles of photoperiod and testosterone in seasonal plasticity of the avian song control system

The song control nuclei of songbirds undergo pronounced seasonal changes in size and neuronal attributes. The mechanisms by which seasonal changes in environmental variables such as photoperiod mediate seasonal changes in these brain regions are not known. Manipulations of photoperiod and/or testosterone in captive songbirds induce seasonal changes in the size of song nuclei comparable to those observed in wild songbirds. It is unclear, however, whether the effects of photoperiod on the song nuclei are mediated by testosterone or by steroid-independent mechanisms. We independently manipulated photoperiod and testosterone in castrated male Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) to determine the contributions of steroid-dependent and -independent actions of photoperiod to seasonal changes in the size and neuronal attributes of song nuclei. Testosterone implants increased the size of several song nuclei, regardless of photoperiod. Photoperiod exerted small but significant steroid-independent effects on the volume of the higher vocal center and the size of neurons in the robust nucleus of the archistriatum. Photoperiod also modulated the effect of testosterone on the size of area X; testosterone treatment had a more pronounced effect on the size of area X on short days than on long days. These results suggest that although testosterone is the primary factor mediating seasonal changes in neural attributes of the song nuclei, photoperiod may act via mechanisms that are independent of steroid levels to supplement or modulate the actions of testosterone.

Evidence that nitric oxide enhances cadmium toxicity by displacing the metal from metallothionein

Cadmium is carcinogenic in humans and rodents. Although extensive evidence indicates that the toxicity and genotoxicity of Cd is ameliorated by binding to cysteine clusters in metallothionein (MT), the factors governing Cd release at intracellular target sites remain unknown. Nitric oxide is a pollutant gas and an important intercellular messenger in the inflammatory immune response. When growing Chinese hamster ovary cells were treated for 24 h with 0.5, 0.75, or 1.0 mM CdCl2 followed by a 1-h exposure to 1.0, 1.5, or 2.0 mM 1,1-diethyl-2-hydroxy-2-nitrosohydrazine (DEA/NO), an NO-generating sodium salt, NO enhanced Cd-induced inhibition of colony forming ability without affecting Cd-induced cytolethality. In experiments designed to determine whether NO acts by displacing Cd from cellular MT, cells treated with 2.0 mM CdCl2 followed by 1.5 or 3.0 mM DEA/NO exhibited 29 and 38% reductions, respectively, in the amount of Cd bound to MT. When purified rat liver MT was used to further characterize NO-induced release of Cd from MT, dose-related increases in Cd displacement were observed at DEA/NO concentrations between 0.1 and 0.5 mM, and a plateau was reached at 3 mol of Cd displaced/mol of MT at higher DEA/NO concentrations. Compared to cells exposed to Cd or DEA/NO alone, cells treated with Cd followed by DEA/NO also exhibited a transient 2-3-fold decrease in c-myc proto-oncogene expression. Taken together, our results support the hypothesis that NO mediates Cd release from MT in vivo and suggest that intracellular generation of free Cd may induce DNA damage and force cells into a period of growth arrest. Such findings may have particular relevance with regard to the etiology of Cd-induced carcinogenesis in human populations.

Using alcohol expectancies to predict adolescent drinking behavior after one year

An accumulating literature has shown the influence of childhood experiences associated with alcohol use on later drinking practices. Recent studies have suggested that alcohol-related expectancy may serve as an intervening variable to connect these early experiences with the later, proximal decision to drink when opportunities for actual alcohol consumption arise. Those studies, however, have collected expectancy and drinking data concurrently, whereas the present study for the first time reports on the power of expectancies measured in early adolescents (seventh and eighth grades) to predict self-reported drinking onset and drinking behavior measured a full year later. Results show that five of seven expectancy scores readily discriminated between nonproblem drinkers and those subsequently beginning problem drinking and accounted for a large portion of the variance in a continuous quantity/frequency index and a problem drinking index. The strength of these timelagged relations strengthens the case for inferring that expectancies have causal power on drinking behavior and suggests prevention strategies.

Seasonal plasticity and sexual dimorphism in the avian song control system: stereological measurement of neuron density and number

Differences in neuron density and number are associated with seasonal plasticity and sexual dimorphism in the avian song control system. In previous studies, neuron density and number in this system have been quantified primarily through nonstereological approaches in thick tissue sections by using the nucleolus as the unit of count. The reported differences between seasons and sexes may be inaccurate due to biases introduced by neuron splitting during sectioning. We used the unbiased optical disector technique on tissue from three previous studies (two investigations of seasonal plasticity and one investigation of sexual dimorphism in avian song nuclei) to assess seasonal and sex differences in neuron density and number. In two song nuclei, HVc and the robust nucleus of the archistriatum (RA), the optical disector yielded intergroup differences in neuron density and number that coincided well with the three previous reports. We also estimated neuron number and density with a random, systematic, nonstereological counting protocol that used the neuronal nucleolus as the unit of count. We compared this method directly to the optical disector. In all cases, the two neuron-counting methods produced similar estimates of neuron number and density; the differences between treatment groups were equally discernible regardless of the counting method used. This study confirms previously reported seasonal and sex differences in the HVc and the RA by use of stereology and indicates that a random, systematic, nonstereological neuron-counting protocol is accurate and is well suited to the study of these phenomena in the avian song control system.

Assessment of primary and metastatic ovarian cancer by positron emission tomography (PET) using 2-[18F]deoxyglucose (2-[18F]FDG)

The potential of positron emission tomography (PET) to distinguish benign from malignant ovarian tissue was evaluated by comparing the results of F-18 fluoro-2-D-deoxyglucose (F-18-FDG) PET scans with computed tomography and surgical findings. If sufficiently sensitive, this method might play a role in localizing metabolically active tumor sites for diagnosis, staging, and follow-up of ovarian cancer. Fifty-one patients had imaging studies prior to laparotomy for suspected ovarian cancer. PET scans were done with an ECAT 931-08-12 or ECAT EXACT (Model 921, Siemens/CTI, Knoxville, TN) after iv injection of 185-370 MBq of F-18-FDG. (ECAT is a trade name for "emission computerized axial tomograph.") Data were acquired in dynamic scanning mode and time activity curves (TACs) were evaluated in multiple regions of interest identified by visual interpretation of the PET scans. Scan interpretation, standardized uptake values, and TAC profiles were related to surgical and histological findings. The results of this pilot study show good correlation between PET and histological findings. The positive predictive value of PET for ovarian cancer was 86% and, perhaps more important, the negative predictive value was 76%. This early work indicates that PET may be useful in the management of patients with ovarian neoplasms by identifying occult foci of metabolically active tumor that do not appear on morphological studies.

Human in vivo comparative study of zinc and copper transmetallation after administration of magnetic resonance imaging contrast agents

RATIONALE AND OBJECTIVES

The authors compare in vivo transmetallation of three magnetic resonance contrast agents in humans in terms of their kinetic stability.

METHODS

Blood and urine samples were taken before and after the intravenous injection of gadolinium (Gd)-HP-DO3A, Gd-DTPA, or Gd-DTPA-BMA at 0.1 mmol/kg to healthy volunteers. Serum and urine were assayed for zinc, copper, and Gd, using inductively coupled plasma atomic emission spectrometer.

RESULTS

Gadolinium-DTPA-BMA caused the highest increase in zinc excretion among the three agents. Gadolinium-HP-DO3A did not cause a significant increase in zinc excretion. In serum, although Gd-DTPA-BMA exhibited a decrease in zinc concentration, the difference between the drugs was not statistically significant.

CONCLUSIONS

The difference in observed zinc excretion among the chelates studied reflects in vivo transmetallation of the magnetic resonance contrast media and correlates with the respective kinetic inertia for transmetallation, rather than thermodynamic stability constants. Gadolinium-HP-DO3A was found to be the most kinetically inert among the three drugs tested.

Effects of eicosapentaenoic and gamma-linolenic acid on lung permeability and alveolar macrophage eicosanoid synthesis in endotoxic rats

OBJECTIVES

Proinflammatory eicosanoids (cyclooxgenase and lipoxygenase metabolites of arachidonic acid) released by alveolar macrophages play an important role in endotoxin-induced acute lung injury. We investigated the effect of prefeeding rats for 21 days with enteral diets that provided the anti-inflammatory fatty acids, eicosapentaenoic acid and gamma-linolenic acid (derived from fish oil and borage oil, respectively), as compared with an n-6 fatty acid-enriched diet (corn oil) on the following: a) lung microvascular protein permeability, arterial blood pressure, and platelet and white blood cells in a model of endotoxin-induced acute lung injury; b) alveolar macrophage prostaglandin and leukotriene synthesis; and c) liver and alveolar macrophage phospholipid fatty acid composition.

DESIGN

Prospective, randomized, controlled, double-blind study.

SETTING

Research laboratory at a university medical center.

SUBJECTS

Male Long-Evans rats, weighing 250 g.

INTERVENTIONS

Rats were randomized into four dietary treatment groups and fed nutritionally complete diets (300 kcal/kg/day), containing 55.2% of the total calories from fat with either 97% corn oil, 20% fish oil, 20% fish and 5% borage oil, or 20% fish and 20% borage oil for 21 days. On day 22, lung microvascular protein permeability, mean arterial pressure, and platelet and white blood cell counts were determined for 2 hrs after an intravenous injection of Salmonella enteritidis endotoxin (10 mg/kg). In a second group of prefed rats, the phospholipid fatty acid composition was determined in liver and alveolar macrophages. Alveolar macrophages were harvested by bronchoalveolar lavage and stimulated in vitro with a calcium ionophore (A23187), and the concentrations of leukotrienes B4 and B5, thromboxane A2, prostaglandin E2, and 6-keto-prostaglandin F1 alpha were measured in a third group of prefed rats.

MEASUREMENT AND MAIN RESULTS

Lung permeability was greatest with corn oil and was significantly attenuated with 20% fish oil and 20% fish and 5% borage oil, and this effect approached significance with 20% fish and 20% borage oil (p = .06). The early and late hypotensive effects of endotoxin were attenuated with 20% fish oil, 20% fish and 5% borage oil, and 20% fish and 20% borage oil, as compared with corn oil. Concentrations of leukotriene B4, prostaglandin E2, and thromboxane B2 released from A23187-stimulated alveolar macrophages were significantly lower with 20% fish oil and 20% fish and 20% borage oil, as compared with corn oil. The increase in lung microvascular protein permeability with 20% fish and 20% borage oil was not significantly different than the lung microvascular protein permeability that was found in animals receiving 20% fish oil (p = .20) and 20% fish and 5% borage oil (p = .31). Alveolar macrophage and liver phospholipid concentrations of arachidonic acid were lower, and the concentrations of eicosapentaenoic acid and docosahexaenic acid were higher, with 20% fish oil, and 5% borage oil, and 20% fish and 20% borage oil, as compared with corn oil. Dihomo-gamma-linolenic acid, the desaturated and elongated intermediate of gamma-linolenic acid, was increased with 20% fish and 20% borage oil, as compared with 20% fish oil and 20% fish and 5% borage oil.

CONCLUSIONS

The severity of pulmonary microvascular protein permeability and the degree of hypotension were reduced with fish or fish and borage oil diets, as compared with corn oil, in endotoxic rats. The reduced synthesis of the proinflammatory arachidonic acid-derived mediators, leukotriene B4, thromboxane B2, and prostaglandin E2 from stimulated alveolar macrophages was indicative of a decrease in arachidonic acid and an increase in eicosapentaenoic acid and docosahexaenoic acid in cell membrane phospholipids.

Differentiating benign from malignant lung lesions using "quantitative" parameters of FDG PET images

Fluorine-18 labeled deoxyglucose positron-emission tomography (FDG-PET) applications in oncology include the differential diagnosis of chest masses and single pulmonary nodules. However, FDG is not tumor-specific; rather, it also accumulates in inflammatory processes. This study was performed to identify image parameters that would improve the specificity of PET.

METHODS

Twenty-six patients who had benign and malignant lung lesions were examined retrospectively. Positron-emission tomography data were acquired in dynamic scanning mode after intravenous bolus of 250-402 MBq of FDG. Standardized uptake values (SUVs) were calculated and Patlak analyses were performed in selected regions of interest in the PET images. Positron-emission tomography results were related to histological diagnosis (N = 49) or clinical follow-up (N = 3).

RESULTS

The specificity and sensitivity of the original PET scan reports, which was based on visual image interpretation and loosely applied SUVs, was 100% and 73%, respectively. Using the SUVs with a cut-off value of 3.8 and Kpat value with a cut-off at 0.025 min-1 improved the specificity to 81% and 85%.

CONCLUSION

FDG-PET image interpretation can be facilitated by using SUV information or the accumulation rate of the radiotracer (Patlak). With additional validation, this method could have a significant cost-effective impact on the medical/surgical management of chest masses.

Evaluation of the direct genotoxic potential of cadmium in four different rodent cell lines

Cadmium is a toxic environmental contaminant that is carcinogenic in humans and laboratory animals. Although the mechanism underlying cadmium carcinogenesis has not yet been determined experimental evidence suggests that the stress-inducible, metal-binding proteins, metallothioneins, may mediate organ specificity. In the present study, four different rodent cell lines (Chinese hamster ovary cells, rat L6 myoblast cells, rat Clone 9 liver cells, and rat TRL 1215 liver cells) were exposed to 0, 1, 5, 10, 50, or 100 microM CdCl2 and monitored for evidence of direct DNA damage. A microfiltration assay was used to measure DNA strand breaks and a filter-binding assay was used to measure DNA-protein crosslinks, two lesions that have been associated with cadmium exposure and may mediate genotoxicity of the metal. Although variability in sensitivity to DNA damage was evident between the different cell lines, in all of the cell lines tested, increases in DNA damage were observed only at cadmium doses that completely arrested cell growth. In addition, in three of the four cell lines tested, induction of metallothionein had no substantial protective effect against cadmium-induced cytotoxicity or genotoxicty. While protection against cadmium-induced DNA strand breakage with metallothionein preinduction was observed in the TRL 1215 rat liver cells, metallothionein preinduction did not protect against cadmium-induced DNA-protein crosslinking in that cell line. Taken together, our results support the hypothesis that cadmium is not directly genotoxic.

Analysis of genetic and phenotypic heterogeneity in juvenile polyposis

BACKGROUND

Juvenile polyposis syndrome (JPS) is characterised by gastrointestinal (GI) hamartomatous polyposis and an increased risk of GI malignancy. Juvenile polyps also occur in the Cowden (CS), Bannayan-Ruvalcaba-Riley (BRRS) and Gorlin (GS) syndromes. Diagnosing JPS can be problematic because it relies on exclusion of CS, BRRS, and GS. Germline mutations in the PTCH, PTEN and DPC4 (SMAD4) genes can cause GS, CS/BRRS, and JPS, respectively.

AIMS

To examine the contribution of mutations in PTCH, PTEN, and DPC4 (SMAD4) to JPS.

METHODS

Forty seven individuals from 15 families and nine apparently sporadic cases with JPS were screened for germline mutations in DPC4, PTEN, and PTCH.

RESULTS

No patient had a mutation in PTEN or PTCH. Five different germline mutations were detected in DPC4; three of these were deletions, one a single base substitution creating a stop codon, and one a missense change. None of these patients had distinguishing clinical features.

CONCLUSIONS

Mutations in PTEN and PTCH are unlikely to cause juvenile polyposis in the absence of clinical features indicative of CS, BRRS, or GS. A proportion of JPS patients harbour DPC4 mutations (21% in this study) but there remains uncharacterized genetic heterogeneity in JPS.

Influence of Pitfall and Drift Fence Design on Capture Rates of Small Vertebrates in Semi-Arid Habitats of Western-Australia

The influence of several attributes of pitfall and drift fence design on capture rates of small vertebrates was examined over 12 months in semi-arid habitats of Western Australia. Large 28 cm diameter pits (20 L buckets), captured significantly more animals than smaller pits made of 16 cm diameter PVC piping. Amongst taxonomic groups, large lizards and geckos showed highly significant biases for large pits, frogs, small lizards, and snakes and legless lizards less so, while small mammals were caught equally often in both sizes. All faunal groups except geckos showed an overall significant increase in capture rates with increasing fence length, but the optimal length per pit cannot be accurately determined from our data. Faunal groups showed a dichotomy in responses to temporary verus permanent drift fences. Independent fenced pits produced significantly higher capture rates than those in a conventional driftline. Variations in species responses to different design attributes probably reflect differing modes of behaviour and activity. We conclude that for our study areas, many large pits installed as a grid at 10-20 m spacing, each with a permanently erected short drift fence (e.g. 7-10 m), should produce excellent results for both autecological and synecological studies.

Coronary reperfusion in primates. Serial electrocardiographic and histologic assessment

After acute coronary occlusion in primates, the time period during which reperfusion results in significant salvage of reversibly injured myocardium was investigated. In 23 monkeys, the left anterior descending coronary artery was occluded from 1 to 6 h; and in 5 others, occlusion was maintained for the 1-wk study. Unipolar epicardial electrocardiograms were monitored from mapping points on the anterior and lateral left venticle. S-T segment elevation (S-T upward arrow) and R + S wave amplitude (RS) were measured before occlusion and at regular intervals during occlusion and reperfusion. Summated S-T upward arrow (SigmaS-T upward arrow) and summated RS (SigmaRS), computed for mapping points demonstrating greater than 2 mV S-T upward arrow, were used as serial measures of electrical injury. SigmaS-T upward arrow peaked within 2-h postocclusion and then gradually declined throughout the period of occlusion suggesting the progress of infarction within the area of injury. After reperfusion SigmaS-T upward arrow rapidly declined to near cnotrol values indicating the extent of reversible injury. During the period of occlusion, the magnitude of voltage loss in SigmaS-T upward arrow as a percent of maximum SigmaS-T upward arrow was proportional to the duration of occlusion, though the rate of loss decreased with increasing time of occlusion. Reperfusion after 6 h of occlusion resulted in reversal of only a small remaining component of the maximum current of injury. The voltage decrease in SigmaRS (from control values) was proportional to the duration of occlusion, though the decrease was accelerated during the first 2-h postocclusion. Whereas reperfusion interrupted the decline in SigmaRS, a consistent increase in SigmaRS postreperfusion was observed only after occlusion of 1 h. With respect to reperfusion groups, significance in SigmaS-T upward arrow voltage loss as a percent of maximum SigmaS-T upward arrow was demonstrated between 2-h and 4-h, 4- and 6-h, and 6-h and chronically ligated animals. Significance in SigmaRS voltage loss as a percent of control SigmaRS was demonstrated between 2- and 4-h, and 4- and 6-h reperfusion groups. Hearts were excised at 7 days for histological assessment of infarct size. Planimetric determination of left ventricular areas and areas of necrosis using slides made from 10 serial cross sections were used in estimating the percent of left ventricle infarcted. A significant reduction in infarct size was demonstrated between reperfused animals at 2 h and the 4- and 6-h reperfusion groups. A trend was noted suggesting increasing infarct size up to 6 h after experimental occlusion.