Are Different Modes of Weight Loss Associated with Survival in Oropharyngeal Cancer?

PURPOSE/OBJECTIVE(S)

Patients with oropharyngeal squamous cell carcinomas (OPSCC) often lose weight during radical radiotherapy (RT). Nutritional intervention is required in case of severe weight loss. However, weight loss does not provide full insight into body composition changes. Muscle mass is emerging as an important prognostic factor in cancer patients. We employed on-treatment cone-beam CT (CBCT) scans to monitor muscle mass and weight loss under the hypothesis that different modes of weight loss exist and may impact overall survival (OS).

MATERIALS/METHODS

A retrospective analysis of 197 OPSCC patients treated with definitive or adjuvant (chemo)RT. Weekly weight measurements & CBCTs were collected. Patients were included if at least two time-points were available and the interval between the first and last was between 15-50 days. CBCTs were normalized to account for calibration differences between treatment machines. An in-house deep-learning model automatically segmented the skeletal muscle compartment at C3 on all CBCTs. Segmentations were visually checked and failures removed. Skeletal muscle volume (SMV, in mm3) was extracted after thresholding for intra-muscular fat. Relative changes in weight & SMV were then calculated. Linear models were fitted to each trajectory for every patient and slopes were estimated. The following weight & SMV categories were defined to generate equal groups: lost (more than 0.4 standard deviations (SDs) below the mean (M)), maintained (within +/- 0.4 SDs of M) or gained (more than 0.4 SDs above the M). Table 1 highlights the nine modes of body composition change. The prognostic value of these was investigated in multivariable Cox models accounting for age, sex, disease stage, oropharynx subsite, smoking status, performance status (PS), tumor p16 status, baseline weight & SMV, and treatment prescribed. The primary endpoint was OS.

RESULTS

Mean weight & SMV changes during treatment were -0.047±0.001% & -0.044±0.019% per day. In multivariable analysis, gaining weight & losing SMV was identified as a significant risk factor for OS (p = 0.01, hazard ratio [95% CI]: 4.59 [1.40-15.10]). In this sub-group, mean weight & SMV change were +0.054±0.008% & -0.396±0.030% per day. PS>2 (p<0.001) & lower baseline weight (p = 0.02) were also significantly associated with OS.

CONCLUSION

Patients losing substantial SMV but mildly gaining weight have significantly worse OS than others. This suggests there exists a group of patients where nutritional support is needed, but not offered because they maintain weight during treatment. Although our results need validation, continual monitoring of muscle condition during RT would allow these patients to be identified and promptly targeted for nutritional support.

Translation norms for Malay and English words: The effects of word class, semantic variability, lexical characteristics, and language proficiency on translation

Translation equivalents are widely used in bilingual research concerning word processing (e.g., Eddington & Tokowicz, 2013; Jouravlev & Jared, 2020) and second-language vocabulary learning (e.g., Bracken et al., 2017; Degani et al., 2014). Although translation norms exist in several languages, to date there are no Malay-English translation norms. This study presents the first Malay-English translation norms collected with highly proficient Malay-English bilinguals. Furthermore, the study investigates the impact of lexical characteristics on translation ambiguity. The forward translation (FT) task (N = 30) collected English translations for 1004 Malay words selected from the Malay Lexicon Project (Yap et al., 2010), and subsequently the backward translation (BT) task (N = 30) gathered Malay translations for 845 English words obtained from the FT phase. The data revealed a high prevalence of translation ambiguity in both translation directions. Specifically, verbs, adjectives, and class-ambiguous words were more translation-ambiguous than nouns. Furthermore, within-language semantic variability and word length were positively correlated with translation ambiguity, whereas word frequency only correlated with translation ambiguity in FT. Word length and word frequency of the source words and their translations were positively correlated. Intriguingly, only in FT were bilinguals with higher Malay proficiency more likely to provide accurate and dominant translations for the Malay words. These findings contrast with those reported in translation norming studies involving other language pairs. The translation norms provide a useful resource for bilingual language studies involving Malay-English bilinguals.

Temporal Incidence and Patterns of Distant Failure for Human Papillomavirus (HPV) Related Oropharyngeal Cancer

PURPOSE/OBJECTIVE(S)

HPV related oropharyngeal cancer (HPV-OPC) enjoys improved treatment outcomes relative to non-HPV related disease but suffers from similar rates of distant metastases (DM) following treatment. Emerging data supports radical intent therapy for oligometastatic relapsed HPV-OPC, suggesting early diagnosis of DM may be beneficial to outcome. We assess temporal patterns in distance relapse to investigate rationalization of post treatment imaging.

MATERIALS/METHODS

A retrospective single center cohort study was carried out of consecutive HPV-OPC treated with radical intent (chemo)radiotherapy ((CT)RT) between 2011 and 2020. Electronic records were reviewed to identify location and timing of development of DM. Oligometastatic (OM) state was defined as

RESULTS

A total of 793 HPV-OPC patients were identified with median follow-up 3.15 years (range 0.2-8.9). The median time to recurrence was 15.1 months (range: 2.6-63 months). 87% of DM occurred in the first two years after treatment. Pattern of failure by stage are shown in table 1. Indications for scans performed identifying DM alone were symptoms (66%), follow-up imaging based on previous radiological findings (15%), disease response assessment imaging (15%), and incidental findings (4%). Sites of distant metastasis were lung (64%), thoracic nodes (36.5%), bone (27%), visceral (23%), brain (4%) and skin (2%). The sites of visceral metastasis involvement included liver (92%), Adrenal (18%), kidney (18%), and spleen (9%). Treatment offered to patients with OM alone was best supportive care (46%), palliative chemotherapy (15.4%), palliative RT (23%), immunotherapy (8%), and one patient lost to follow up (8%). SBRT was not available during time period. Median survival following diagnosis was 17.5 months (range 4.4-85.4 months).

CONCLUSION

Despite no routine imaging beyond initial treatment response assessment, we identify a small minority of HPV OPC patients with OM recurrence that is associated with better outcome and occasional long-term cure from aggressive therapy. The majority (69%) of DM occur in the thorax/upper abdomen of patients in the first two years post treatment. This finding supports the potential utility of regular imaging of thorax/upper abdomen during early follow.

Collapse

Key Words Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

J Gaffney The Christie NHS Foundation Trust, Manchester, United Kingdom
A Ramzan Department of Radiology, The Christie NHS Foundation Trust, Manchester, United Kingdom
T Dinizulu Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
D O Onamusi The University of Manchester, Manchester, United Kingdom
G Motamedi-Ghahfarokhi The University of Manchester, Manchester, United Kingdom
H Mistry The University of Manchester, Manchester, United Kingdom
G Price The Christie NHS Foundation Trust, Manchester, United Kingdom; The University of Manchester, Manchester, United Kingdom
K Garcez Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
C Hughes Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
D D Thomson The Christie NHS Foundation Trust, Manchester, United Kingdom
L W Lee Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
Y Jain Department of Radiology, The Christie NHS Foundation Trust, Manchester, United Kingdom
J M Price Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
A McPartlin Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada

Collapse

LexMAL: A quick and reliable lexical test for Malay speakers

Objective language proficiency measures have been found to provide better and more consistent estimates of bilinguals' language processing than self-rated proficiency (e.g., Tomoschuk et al., 2019; Wen & van Heuven, 2017a). However, objectively measuring language proficiency is often not possible because of a lack of quick and freely available language proficiency tests (Park et al., 2022). Therefore, quick valid vocabulary tests, such as LexTALE (Lemhöfer & Broersma, 2012) and its extensions (e.g., LexITA: Amenta et al., 2020; LEXTALE-FR: Brysbaert, 2013; LexPT: Zhou & Li, 2022) have been developed to reliably assess language proficiency of speakers of various languages. The present study introduces a Lexical Test for Malay Speakers (LexMAL), which estimates language proficiency for Malay first language (L1) and second language (L2) speakers. An initial 180-item LexMAL prototype was evaluated using 60 Malay L1 and 60 L2 speakers in Experiment 1. Sixty words and 30 nonwords with the highest discriminative power that span across the full difficulty range were selected for the final LexMAL based on point-biserial correlations and an item response theory analysis. The validity of LexMAL was demonstrated through a reliable discrimination between L1 and L2 speakers, significant correlations between LexMAL scores and performance on other Malay language tasks (i.e., translation accuracy and cloze test scores), and LexMAL outperforming self-rated proficiency. A validation study (Experiment 2) with the 90-item final LexMAL tested with a different group of Malay L1 (N = 61) and L2 speakers (N = 61) replicated the findings of Experiment 1. LexMAL is freely available for researchers at www.lexmal.org .

Similar long-term swallowing outcomes for accelerated, mildly-hypofractionated radiotherapy compared to conventional fractionation in oropharynx cancer: a multi-centre study

BACKGROUND AND PURPOSE

There is renewed interest in hypofractionated radiotherapy, but limited data and a lack of consensus to support use for head and neck cancer. In this multicentre analysis we compared outcomes for patients with oropharynx squamous cell carcinoma (OPSCC) treated with conventional and accelerated, mildly hypofractionated radiotherapy without chemotherapy.

MATERIALS AND METHODS

A multi-centre, observational study of consecutive OPSCCs treated between 2015 and 2018. Patients underwent curative-intent radiotherapy (oropharynx and bilateral neck) using conventionally fractionated (70 Gy in 35 fractions over 7 weeks, n = 97) or accelerated, mildly hypofractionated (65-66 Gy in 30 fractions over 6 weeks, n = 136) radiotherapy without chemotherapy. Locoregional control (LRC) and overall survival (OS) were compared. Patients alive and cancer-free at a minimum of 2 years post-radiotherapy (n = 151, 65%) were sent an MD Anderson Dysphagia Inventory (MDADI) questionnaire to assess swallow function.

RESULTS

LRC and OS were similar across schedules (p = 0.78 and 0.95 respectively, log-rank test). Enteral feeding rates during radiotherapy appeared higher in the 7-week group though this did not reach statistical significance (59% vs 48%, p = 0.08). Feeding rates were similar at 1 year post radiotherapy for both groups (10% vs 6%, p = 0.27). 107 patients returned MDADI questionnaires (71%); there were no differences between the 6- and 7-week groups for median global (60.0 vs 60.0, p = 0.99) and composite (65.8 vs 64.2, p = 0.44) MDADI scores.

CONCLUSION

Patients with OPSCC treated with radiotherapy alone have similar swallowing outcomes, LRC and OS following accelerated, mild hypofractionation and standard fractionation schedules, supporting its use as a standard-of-care option for patients unsuitable for concurrent chemotherapy.

High variability phonetic training in adaptive adverse conditions is rapid, effective, and sustained

This paper evaluates a novel high variability phonetic training paradigm that involves presenting spoken words in adverse conditions. The effectiveness, generalizability, and longevity of this high variability phonetic training in adverse conditions was evaluated using English phoneme contrasts in three experiments with Malaysian multilinguals. Adverse conditions were created by presenting spoken words against background multi-talker babble. In Experiment 1, the adverse condition level was set at a fixed level throughout the training and in Experiment 2 the adverse condition level was determined for each participant before training using an adaptive staircase procedure. To explore the effectiveness and sustainability of the training, phonemic discrimination ability was assessed before and immediately after training (Experiments 1 and 2) and 6 months after training (Experiment 3). Generalization of training was evaluated within and across phonemic contrasts using trained and untrained stimuli. Results revealed significant perceptual improvements after just three 20-minute training sessions and these improvements were maintained after 6 months. The training benefits also generalized from trained to untrained stimuli. Crucially, perceptual improvements were significantly larger when the adverse conditions were adapted before each training session than when it was set at a fixed level. As the training improvements observed here are markedly larger than those reported in the literature, this indicates that the individualized phonetic training regime in adaptive adverse conditions (HVPT-AAC) is highly effective at improving speech perception.

Randomized, Controlled, Crossover trial of Prevention of Clindamycin-Induced Gastrointestinal Signs Using a Synbiotic in Healthy Research Cats

Background

Synbiotics often are prescribed to limit antibiotic‐associated gastrointestinal signs (AAGS) in cats, but data to support this recommendation are lacking.

Objective

To determine whether synbiotic co‐administration mitigates AAGS in healthy research cats treated with clindamycin.

Animals

16 healthy research cats.

Methods

A randomized, double‐blinded, placebo‐controlled, 2‐way, 2‐period, crossover study with a 6‐week washout was performed. Each study period consisted of a 1‐week baseline and a 3‐week treatment period. Cats received 75 mg clindamycin with food once daily for 3 weeks, followed 1 hour later by either 2 capsules of a synbiotic or placebo. Food consumption, vomiting, fecal score, and completion of treatment were compared using repeated measures split plot or crossover designs with covariates, with P < 0.05 considered significant.

Results

Cats that received the synbiotic were more likely to complete treatment in period 1 (100% vs. 50%, P = 0.04). Cats vomited less when receiving the synbiotic but this was not significant, but there were significant period effects (F‐value = 11.4, P < 0.01). Cats had higher food intake while receiving the synbiotic (F‐value = 31.1, P < 0.01) despite period effects (F‐value = 8.6, P < 0.01). There was no significant effect of treatment on fecal scores, which significantly increased over time (F‐value = 17.9, P < 0.01).

Conclusions and Clinical Importance

Administration of a synbiotic 1 hour after clindamycin administration decreased hyporexia and vomiting in healthy cats. Additionally, significant period effects suggest that clinical benefits of synbiotic administration persist for at least 6 weeks after discontinuation, decreasing the severity of AAGS in cats that subsequently received clindamycin with placebo. Unlike in people, synbiotic administration did not decrease antibiotic‐associated diarrhea.

Imaging hypoxia in tumours with advanced MRI

Tumour hypoxia results in biological alterations that leads to a more aggressive disease phenotype and is associated with resistance to treatment. In this review, we discuss current magnetic resonance imaging techniques, which can be applied to evaluate tumour hypoxia, highlighting the principles of each technique, their pre-clinical and clinical deployment, as well as their strengths and limitations. The potential to combine these techniques, and also with other imaging modalities (e.g., PET imaging) using a multiparametric approach, may further improve our understanding of the complex interaction of vascular supply, oxygen diffusion and tissue metabolism in pathogenesis of tumour hypoxia; and its reversal with treatment.

Using chemistry and microfluidics to understand the spatial dynamics of complex biological networks

Understanding the spatial dynamics of biochemical networks is both fundamentally important for understanding life at the systems level and also has practical implications for medicine, engineering, biology, and chemistry. Studies at the level of individual reactions provide essential information about the function, interactions, and localization of individual molecular species and reactions in a network. However, analyzing the spatial dynamics of complex biochemical networks at this level is difficult. Biochemical networks are nonequilibrium systems containing dozens to hundreds of reactions with nonlinear and time-dependent interactions, and these interactions are influenced by diffusion, flow, and the relative values of state-dependent kinetic parameters. To achieve an overall understanding of the spatial dynamics of a network and the global mechanisms that drive its function, networks must be analyzed as a whole, where all of the components and influential parameters of a network are simultaneously considered. Here, we describe chemical concepts and microfluidic tools developed for network-level investigations of the spatial dynamics of these networks. Modular approaches can be used to simplify these networks by separating them into modules, and simple experimental or computational models can be created by replacing each module with a single reaction. Microfluidics can be used to implement these models as well as to analyze and perturb the complex network itself with spatial control on the micrometer scale. We also describe the application of these network-level approaches to elucidate the mechanisms governing the spatial dynamics of two networkshemostasis (blood clotting) and early patterning of the Drosophila embryo. To investigate the dynamics of the complex network of hemostasis, we simplified the network by using a modular mechanism and created a chemical model based on this mechanism by using microfluidics. Then, we used the mechanism and the model to predict the dynamics of initiation and propagation of blood clotting and tested these predictions with human blood plasma by using microfluidics. We discovered that both initiation and propagation of clotting are regulated by a threshold response to the concentration of activators of clotting, and that clotting is sensitive to the spatial localization of stimuli. To understand the dynamics of patterning of the Drosophila embryo, we used microfluidics to perturb the environment around a developing embryo and observe the effects of this perturbation on the expression of Hunchback, a protein whose localization is essential to proper development. We found that the mechanism that is responsible for Hunchback positioning is asymmetric, time-dependent, and more complex than previously proposed by studies of individual reactions. Overall, these approaches provide strategies for simplifying, modeling, and probing complex networks without sacrificing the functionality of the network. Such network-level strategies may be most useful for understanding systems with nonlinear interactions where spatial dynamics is essential for function. In addition, microfluidics provides an opportunity to investigate the mechanisms responsible for robust functioning of complex networks. By creating nonideal, stressful, and perturbed environments, microfluidic experiments could reveal the function of pathways thought to be nonessential under ideal conditions.

Physiological levels of beta-amyloid induce cerebral vessel dysfunction and reduce endothelial nitric oxide production

beta-amyloid (A beta), the major component of senile plaques in Alzheimer's disease (AD), normally circulates in the blood at nanomolar levels but is elevated in AD. Previous studies have found that high concentrations (10(-5)-10(-4) M) of A beta result in neuronal cell death. Here we show that physiological levels of soluble A beta can induce dysfunction in perfused rat cerebral vessels and in cultured endothelial cells. At concentrations of 10(-9)-10(-6) M, A beta induced a significant concentration-dependent reduction of NO production in endothelial cells. At 10(-8) M, A beta significantly decreased the sensitivity of cerebral vessels to acetylcholine (ACh), an endothelium dependent vasodilator. At 10(-7) M and higher concentrations, A beta significantly reduced the maximum response of vessels to ACh, and induced significant endothelial cell death. A beta (10(-9)-10(-5) M) did not cause any detectable change in nitric oxide synthase levels. The results suggest that a modest increase in the concentration of A beta above its normal physiological level in the circulation, as found in the early stages of AD, results in decreased NO production and vessel sensitivity to endothelium-dependent vasodilation that could lead to constricted blood vessels and ischemia in the surrounding tissue. Further increases in A beta concentration, which may occur in the later stages of AD, result in cell death and decreased maximum vasodilator response of cerebral vessels.

Polarity of the transition state controls the reactivity of related charged phenyl radicals toward atom and group donors

Polar effects are demonstrated to be a key factor in controlling the reactivities of related charged phenyl radicals in different exothermic atom and group abstraction reactions in the gas phase. The effects of various meta substituents on the phenyl radicals' reactivity were probed via the measurement of bimolecular reaction rate constants by using Fourier transform ion cyclotron resonance mass spectrometry. This approach requires an additional, charged substituent to be present in the phenyl radical to allow mass spectrometric manipulation. The m-pyridinium group was chosen for this purpose. The substrates studied were allyl iodide, dimethyl disulfide, and tert-butyl isocyanide. Two of the reactions of interest, *I and *SCH(3) transfer, are thought to occur by concerted bimolecular homolytic substitution (S(H)2), and the third one, *CN transfer, by an addition/elimination mechanism. For all three substrates, the reaction rate was found to increase in the following order for the differently substituted phenyl radicals: CH(3) approximately H < Br approximately Cl approximately COOH < NO(2) approximately CN. This trend does not arise from differences in reaction exothermicities or bond dissociation energies but via lowering the reaction barrier by electronic effects. The stabilization of the transition state is attributed to its increased polar character. A semiquantitative measure of the barrier lowering effect for each substituent is obtained from its influence on the electron affinity of the charged radical, as the calculated (B3LYP/6-31+G(d)) adiabatic electron affinities of the radical model systems (ammonium instead of pyridinium charge site) follow the same trend as the reactivities.

A global factor in the Hermann grid illusion or an artifact?

In the first of the present experiments, subjects were required to estimate the strength of the Hermann grid illusion in grids containing various numbers of intersections even though those grids were not actually presented. The positive relationship found by Wolfe (1984) for real grids was, nevertheless, replicated. It is argued that this suggests that a response bias might have been the source of his effect (although other possibilities are also noted). In addition, in a second experiment, subjects who were not aware of the fact that grid size was being manipulated (i.e., between subjects) showed no consistent effect of that factor, thus supporting the same suggestion.

An integrated confocal and magnetic resonance microscope for cellular research

Complementary data acquired with different microscopy techniques provide a basis for establishing a more comprehensive understanding of health and disease at a cellular level, particularly when data acquired with different methodologies can be correlated in both time and space. In this Communication, a brief description of a novel instrument capable of simultaneously performing confocal optical and magnetic resonance microscopy is presented, and the first combined images of live Xenopus laevis oocytes are shown. Also, the potential benefits of combined microscopy are discussed, and it is shown that the a priori knowledge of the high-resolution optical images can be used to enhance the boundary resolution and contrast of the MR images.

Potassium channel openers prevent beta-amyloid toxicity in bovine vascular endothelial cells

There is increasing evidence that the cerebrovasculture may be involved in the pathology of Alzheimer's disease. Here, we report that potassium channel openers (KCOs) inhibit dose and time dependent necrosis induced by beta-amyloid (Abeta) in cultured vascular endothelial cells. Cell proliferation rate was assayed by a colorimetric method. Abeta cytotoxicity and inhibition by the K(ATP) channel opener diazoxide and the K(Ca) channel opener NS1619 was correlated with changes in nitric oxide (NO) production. The protective effects were partly blocked by potassium channel blockers. Toxicity of Abeta and KCO protection was verified by histological examination of endothelial cells with scanning electron microscopy. eNOS levels in endothelial cells were not changed by any of the treatments. The results suggest that disruption of K(+) channels function may be a critical step in Abeta-induced cytotoxicity in endothelial cells by alteration of NO release.

The effect of insecticides on learning in the Africanized honey bee (Apis mellifera L.)

The present study was designed to examine the effects of endosulfan, decis, baytroid, and sevin on the learning ability of Africanized honey bees (Apis mellifera L.). Although these insecticides were recommended by the government of Brazil to control the cotton boll weevil, the effects on bees have been unknown. Results of the present research show that: (1) bees readily consume each of the pesticides when placed in a sucrose solution; (2) the odors of the pesticides are not repellent to bees, and such odors can serve as conditioned stimuli; (3) learning occurs to various degrees when the insecticides are combined with the sucrose solution and used as an unconditioned stimulus; and (4) feeding the insecticides to the bees 1 h prior to conditioning leads to differing mortality. Because of the importance of bees for honey production, as well as pollination of cotton and other crops, recommendations are made for the use of decis and other measures for boll weevil control.http://link. springer-ny.com/link/service/journals/00244/bibs/37n4p529.++ +html</HEA

Estrogen protects peripheral and cerebral blood vessels from toxicity of Alzheimer peptide amyloid-beta and inflammatory reaction

Due to increases in life expectancy, women are living 30 years or more beyond menopause. This has led to an increasing interest in the association between postmenopausal estrogen deficiency and degenerative diseases associated with aging such as cardiovascular disease, osteoporosis and dementia. Women are two times more likely to develop late-onset Alzheimer's disease (AD) than age-matched men. A large number of observational reports and a few randomized clinical trials have indicated that estrogen replacement therapy (ERT) may retard the development and severity of dementia in postmenopausal women. The mechanism underlying the protective action of estrogen in AD is under active investigation. A chronic inflammatory reaction mediated by abnormal deposition of proteins such as amyloid-beta (A beta) is central to the pathology of AD. We investigated the effect of low doses of conjugated estrogen (Premarin) in an animal model of A beta-induced vascular disruption and inflammatory reaction. This rodent model allows live videomicroscopic recording and electron microscopic analysis of peripheral vascular disruption and inflammatory reaction triggered by A beta. Estrogen prevented vascular deposition of A beta, endothelial and vessel wall disruption with plasma leakage, platelet and mast cell activation, and characteristic features of an inflammatory reaction: adhesion and transmigration of leukocytes. The beneficial effect was lost when estrogen treatment was discontinued. Estrogen also protected the cerebral blood vessels from endothelial dysfunction induced by A beta. This novel protective effect of estrogen against A beta cytotoxicity in peripheral and cerebral vasculature may contribute to the therapeutic efficacy of estrogen in AD and coronary vascular disease.

Internal representational models of peers: implications for the development of problematic behavior

The authors investigated the relation between children's knowledge structures for peers and externalizing behavior problems. Initial levels of aggression were evaluated in 135 boys and 124 girls (Grades 1-3; 40% African American, 60% Caucasian) in Year 1 and again in Years 6 and 9. In Year 6, 3 aspects of their social knowledge structures were assessed: quality, density, and appropriateness. Results indicate that knowledge structures are related to children's concurrent levels of externalizing behaviors and that knowledge structures are related to children's concurrent levels of externalizing behaviors and predict externalizing behaviors 3 years later even after controlling for current levels of behavior. In addition, knowledge structures in Year 6 mediate the relation between aggression in Year 1 and externalizing behaviors in Year 9. The role of knowledge structures in the maintenance and growth of children's antisocial behavior is discussed.

The protective effect of K+ channel openers on beta-amyloid induced cerebrovascular endothelial dysfunction

Amyloid angiopathy is characterized by amyloid beta-peptide (A beta) deposition and may contribute to the cerebrovascular abnormalities that precede the onset of Alzheimer's Disease (AD). That aberrant potassium (K+) channel function occurs in AD patients is supported by deleterious effects of A beta on normal fibroblast K+ channels and prevention of A beta-induced toxicity by potassium channel openers (KCOs) in neuronal cell culture. We report here that KCOs protect cerebral and peripheral vessels against the endothelial damage induced by A beta. Pressurized posterior cerebral artery and aortic ring segments from the rat were constricted and then relaxed with the endothelium-dependent vasodilator acetylcholine before and after incubation with A beta (10(-6) M), or pre-treatment with KCOs before the addition of beta-amyloid. Vessels treated with A beta exhibited features of endothelial dysfunction: enhanced vasoconstriction and diminished endothelium-dependent vasodilation. Pre-treatment with KCOs significantly antagonized the A beta effect in both cerebral and aortic vessel segments. This protection was provided by both KCa and KATP channel openers. Endothelial damage by A beta and protection by KCOs was verified by electron microscopy. The K+ channel blocker, TEA, reversed the protective effect of KCO. The results suggest that potassium channel openers protect against A beta induced endothelial dysfunction and that KCOs may have a role in the treatment of degenerative cerebrovascular disease as seen in stroke, AD and aging.

Internal representational models of peers: implications for the development of problematic behavior

The authors investigated the relation between children's knowledge structures for peers and externalizing behavior problems. Initial levels of aggression were evaluated in 135 boys and 124 girls (Grades 1-3; 40% African American, 60% Caucasian) in Year 1 and again in Years 6 and 9. In Year 6, 3 aspects of their social knowledge structures were assessed: quality, density, and appropriateness. Results indicate that knowledge structures are related to children's concurrent levels of externalizing behaviors and that knowledge structures are related to children's concurrent levels of externalizing behaviors and predict externalizing behaviors 3 years later even after controlling for current levels of behavior. In addition, knowledge structures in Year 6 mediate the relation between aggression in Year 1 and externalizing behaviors in Year 9. The role of knowledge structures in the maintenance and growth of children's antisocial behavior is discussed.

Social information-processing patterns as predictors of social adaptation and behavior problems among maltreated children in foster care

OBJECTIVE

The goal of this investigation was to determine if social information-processing patterns were predictive of later social adaptation and behavior problems within a group of maltreated children in foster care.

METHOD

A longitudinal design was used to address the study hypotheses. The sample consisted of 124 maltreated children ages 5 to 10 who had been placed into foster care. Twelve months following entrance into foster care, children were presented with age-relevant hypothetical vignettes to assess the quality of the way in which they process social information. Six to 8 months following this assessment, caregivers completed the Vineland Adaptive Scales and the Child Behavior Checklist.

RESULTS

Measures reflecting unbiased and competent processing were predictive of social adaptation, whereas measures reflecting biased and incompetent processing were predictive of behavior problems. In aggregate, processing measures accounted for a significant proportion of the variance in the outcome measures.

CONCLUSIONS

The findings suggest that the manner in which maltreated children process social information has a bearing on their later social adaptation and behavioral adjustment. Therefore, maltreated children in foster care may benefit from interventions that target the manner in which they process social information.

The war against junk science: the use of expert panels in complex medical-legal scientific litigation

In the legal context, junk science is defined as evidence that is outside of mainstream scientific or medical views. Junk science does not have indicia of reliability and is not generally accepted. Despite the lack of scientific reliability, US courts, expert witnesses and juries are increasingly reliant on junk science in making causation decisions in complex medical liability cases. Courts have accepted junk science even where reliable scientific evidence is available. The United States silicone gel breast implant litigation is a prime example of this phenomenon. The issue of whether silicone breast implants are associated with disease has been a controversial subject for scientists and physicians, an emotional issue for women who have breast implants, and a lucrative business for the lawyers and expert witnesses who are the proponents of junk science. Junk science has provided to juries a quick and convenient explanation for claimed diseases or syndromes which have required years for reliable scientists to conclude are not related to breast implants. The breast implant litigation highlights the often dramatic difference between decisions based upon junk science and decisions grounded in scientific method, fact and reality. Recently, judges involved in the breast implant litigation have become concerned about the use of junk science in light of the growing body of legitimate scientific evidence that breast implants do not cause disease. Several judges have been motivated to take the unique and novel approach of convening scientific panels of independent experts to study the scientific issues and make findings to the court. Through the use of independent scientific experts, several judges have meaningfully assessed the evidence that the litigants present and have prevented or strictly limited the use of junk science in the courtroom. Using this procedure, other judges are weighing the evidence for future cases. This paper will briefly explore the background of mass tort medical products litigation and the development of junk science. The paper will then focus on the history of the breast implant litigation and the steps that the courts have already taken to combat junk science, including the use of scientific panels.

Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program

OBJECTIVE

To study the effects of a 12-week weight loss strategy involving increased physical activity, self-selected hypocaloric diet, and group support on psychological well-being, quality of life, and health practices in moderately obese women.

METHODS

Eighty women aged 20-49 years weighing between 20-50% above 1983 Metropolitan Life Insurance Tables were randomly assigned to a weight loss intervention (6279 kJ/week of physical activity, 33,258-41,462 kJ/week diet and weekly meetings) or served as controls. Subjects were tested pre and post 12-weeks.

RESULTS

The intervention group lost significant (p<0.001) body weight (kg) and body fat (%) compared to controls (-6.07+/-4.01 kg vs. 1.31+/-1.28 kg; 36.8%-32.5% vs. 36.2%-36.0%). Intervention subjects vs. controls achieved significant improvements (p<0.001) in body cathexis (X Change 18.6+/-16.7 vs. 0.7+/-8.6) and estimation of ability to achieve physical fitness (X Change 8.1+/-7.1 vs. 0.9+/-5.9). Various quality of life indices also improved (p<0.01) in the intervention group compared to controls (physical function: X Change 13.5.2+/-16.7 vs. 1.4+/-9.5; vitality: X change 21.7+/-17.9 vs. 2.9+/-20.8; mental health: X change 10.4+/-16.0 vs. 2.3+/-10.1). Similarly, physical activity levels also improved significantly (p<0.0001) in the intervention group (4.4+/-2.3 vs. 0.6+/-1.3; on NASA 0-7 scale).

CONCLUSIONS

Practical weight loss practices such as increased activity, self-selected hypocaloric diet, and group support are effective for weight loss and yield significant health and psychological benefits in moderately obese females.

Some preliminary studies on the ability of Africanized honey bees (Apis mellifera L.) to tolerate cold temperatures when placed inside a refrigerator

Cold is often suggested as an ecological mechanism to prevent the migration of Africanized honey bees. The ability of Africanized honey bees to tolerate cold temperatures was investigated. In one study an observation hive was placed inside a refrigerator at 25 degrees C. The study was conceptualized as a choice experiment in which the colony could remain in a cold environment or leave for a warm environment. Analysis indicated that the bees remained at 9 +/- 1 degrees C for 14 days before leaving. In a second series of studies, testing the tolerance to 0 degree C, 280 bees were placed individually in small metal tubes. The data gathered included survival rate, time to regain consciousness, and ability to feed. Analysis indicated that Africanized bees can survive for up to 3 hr. at 0 degree C with few ill effects. At 4 hr., however, the survival rate is low. Limitations of the study, the use of cold as a possible deterrent to honey bee mites, and suggestions for additional research are discussed.

Inhibition of cGMP mediated relaxation in small rat coronary arteries by block of CA++ activated K+ channels

The functional importance of Ca++ activated K+ (K(Ca)) channels in cGMP mediated relaxation of pressurized septal arteries (internal basal diameter 213 +/- 4 microm) was investigated. Vascular tone was increased by the thromboxane A2 analogue, U-46619 and internal pressure was maintained at 60 mmHg. Vessels were tested with an endothelium independent agonist (nitroprusside) and endothelium dependent agonist (acetylcholine) of nitric oxide which activates soluble guanylate cyclase. Receptor activation of particulate guanylate cyclase was tested by atrial natriuretic peptide. Direct changes in intracellular cGMP concentration were done with the cell permeable analog, 8-Bromo-cGMP. Tetraethylammonium ion (TEA+), 1 mM, significantly inhibited relaxation to nitroprusside from 10(-7) to 10(-3) M with a maximal inhibition of 53 +/- 8% at 10(-3) M. Relaxation to acetylcholine from 10(-9) M to 10(-5) M was significantly inhibited by TEA+ with a maximal inhibition of 52 +/- 13% at 10(-7) M. TEA+ significantly inhibited relaxation to 8-Bromo-cGMP from 10(-6) M to 10(-3) M with a maximal inhibition of 59 +/- 14% at 10(-4) M. The relaxation response to atrial natriuretic peptide from 10(-12) M to 10(-7) M was significantly inhibited by TEA+ with a maximal inhibition of 84 +/- 5% at 10(-11) M. The large conductance K(Ca) channel blocker, iberiotoxin, eliminated the relaxation response to 8-Bromo-cGMP (10(-3) M). The results suggest that a large portion of the dilator action of cGMP is mediated by effects on K+ membrane channels.

beta-Amyloid induces cerebrovascular endothelial dysfunction in the rat brain

beta-Amyloid toxicity plays a central role in the pathology of Alzheimer's disease. Contraction and relaxation responses of pressurized rat posterior cerebral artery were studied before and after in vitro exposure to beta-amyloid. The peptide-induced characteristic features of endothelial dysfunction including enhanced vasoconstriction with serotonin and diminished relaxation to endothelium-dependent vasodilators acetylcholine and bradykinin. Response to the endothelium-independent vasodilator nitroprusside was not affected by beta-Amyloid. beta-amyloid inhibition of acetylcholine-induced vasodilation was prevented by the oxygen radical scavenging enzyme superoxide dismutase. Endothelial destruction and the protective effect of superoxide dismutase was verified by electron microscopy. The results suggest that beta-amyloid peptide produces endothelial dysfunction in cerebral microvessels through reactive oxygen species.

Beta-amyloid-induced coronary artery vasoactivity and endothelial damage

Amyloid beta-peptide (A beta) deposition has been associated with coronary heart disease and neurodegenerative diseases. A link between A beta and free radical generation has been explored in neuronal tissue. We report here on the effect of A beta on pressurized segments of coronary resistance arteries and the role of free radicals. A small oscillatory response to A beta (10[-6] M) that consisted of a relaxation followed by constriction and a return to the basal diameter was observed in all vessels. The thromboxane A2 analog U46619 produced a significantly greater constriction compared with the response before treatment with A beta. The presence of the antioxidant enzyme superoxide dismutase (SOD) reduced both the response to A beta alone and the enhanced response to U46619. Vasodilation responses to acetylcholine (10[-9]-10[-5] M) were virtually eliminated at all concentrations by A beta. We confirmed endothelial cell damage by A beta with electron microscopy. The results suggest that A beta deposition in coronary resistance arteries causes endothelial damage that is mediated through superoxide radicals.

Learning in the Africanized honey bee: Apis mellifera L

Several series of experiments are reported that investigate learning in the Africanized honey bee. In the first series, classical conditioning of proboscis extension was studied by confining bees to small metal tubes where they received pairings of an odor with a 3-s feeding of sucrose. After a number of odor-sucrose pairings, the bees began to extend their proboscis to the odor. Controls include Unpaired, Discrimination, and Pseudoconditioning Groups. This technique was used to look at conditioning to a light CS, and to the odors of beeswax, geraniol, citral, and hexanal. The results indicate that acquisition was best when sucrose was paired with the odor of beeswax. Conditioning to the remaining odors was roughly similar, but acquisition did not occur using a light. In a second series of experiments, odors were no longer followed by sucrose feedings and the conditioned response slowly disappeared. With the exception of geraniol as a CS, this extinction effect did not occur if the animals continued to be fed on an unpaired schedule. In a third series of experiments, conditioned inhibition was demonstrated when geraniol was used as conditioned stimuli, but no effect was found when the odors of hexanal, citral and wax were used. In a fourth series of experiments, unrestrained bees flew back and forth from the laboratory to the hive, where they were taught to distinguish targets based on color and odor. With this technique, color and odor discrimination in the Africanized bees was demonstrated. In addition, it was found that more intruder bees visited the experimental station when the stimuli used were olfactory rather than visual.

Calcium-activated potassium channel-mediated arteriolar relaxation during endotoxic shock

The role of calcium-activated potassium (KCa) channels in the in vivo relaxation of arterioles was investigated before endotoxin shock (Pre-ENDT) and during endotoxin shock at 180 min (Post-ENDT). Diameters of 2nd and 3rd order (A2 and A3) arterioles in the left cremaster muscle of male Sprague-Dawley rats anesthetized with pentobarbital sodium were measured using videomicroscopy. Adenosine (ADO) at 534 micrograms intraarterially, topical ADO at 10(-3) M, and the endothelium-dependent agonist topical acetylcholine (ACH) at 10(-4) M significantly dilated both A2 and A3 arterioles Pre-ENDT and Post-ENDT. Topical tetraethylammonium chloride (TEA) at 1 mM blocked ADO (intraarterially and topical)-induced A2 and A3 arteriolar dilations Pre-ENDT and Post-ENDT. Arteriolar dilation to ACH was maintained Pre-ENDT, but was blocked by TEA in A2 and A3 arterioles Post-ENDT. The endothelium-independent agonist sodium nitroprusside (10(-5) M), when topically applied, caused maximal arteriolar dilation Pre-ENDT and Post-ENDT in the presence of TEA. The data show that vascular smooth muscle KCa channels are a significant factor in ADO-induced relaxation of cremaster microvessels and are not significantly affected by ENDT. The results also suggest that the mechanism for endothelium-dependent ACH vasodilation changes from a non-KCa channel-mediated mechanism Pre-ENDT to a KCa-mediated mechanism Post-ENDT.

Inhibition of cAMP mediated relaxation in rat coronary vessels by block of Ca++ activated K+ channels

The hypothesis for this study is that block of calcium activated potassium (KCa) channels inhibits cAMP induced relaxation in pressurized rat coronary resistance arteries. Pressure-diameter experiments with septal arteries (200-270 microns internal diameter at 60 mmHg and maximum dilation) showed significant basal tone over a range of pressure from 40-120 mmHg. The level of tone was increased with the thromboxane A2 analogue 9,11-dideoxy-11 alpha, 9 alpha-epoxy-methanoprostaglandin F2 alpha (U46619) in all experiments. Receptor activation of the cAMP pathway was done with adenosine (ADO) and isoproterenol (ISO). Tetraethylammonium ion (TEA+), 1mM, significantly inhibited relaxation to ADO (10(-6)-10(-3)M) with a maximal inhibition of 75 +/- 7% (as a % of maximum diameter change with the vasodilator alone) at 10(-3)M ADO. TEA+ inhibited ISO (10(-6)M) relaxation by 63 +/- 9%. Direct activation of the cAMP pathway was done with forskolin and 8-bromo-cAMP. TEA+ significantly inhibited forskolin (10(-6)-10(-4)M) induced relaxation with a maximal inhibition of 81.3 +/- 1.2% at 10(-4)M forskolin. TEA+ and iberiotoxin (10(-7)M) significantly inhibited 8- bromo-cAMP (10(-3)M) induced relaxation by 72 +/- 5% and 56 +/- 3% respectively. The effect of TEA+ on relaxation induced by nitroprusside (a cGMP dependent vasodilator) was not significant. The results show that rat coronary resistance arteries possess significant myogenic tone and modulation of Kca channels plays a major role in cAMP mediated relaxation.

Arteriolar reactivity of endotoxin-tolerant rats after hemorrhage and reinfusion

Adrenergic and endothelium-dependent arteriolar reactivity are greatly reduced in hemorrhagic shock. However, development of tolerance to endotoxin may prevent the decrease. The reactivity of cremaster muscle arterioles was tested in pentobarbital-anesthetized endotoxin-tolerant (ENDT-T) and nontolerant control rats. Tolerance was developed by sublethal intraperitoneal injections of Escherichia coli endotoxin for 4 days (n = 9). Controls received saline (n = 9). Mean arterial pressure (MAP), arteriolar diameter-response curves to topical norepinephrine (NE) (10-9M to 10-3M) and responses to 10-3M acetylcholine (ACh) were obtained as follows 1) at control, 2) following hemorrhage to 40 mmHg. 3) after uptake of 25% of bled volume with the remainder infused, and 4) at 240 min post-hemorrhage. The A1, A2, and A3 arterioles were constricted following hemorrhage in the ENDT-T group and in the saline group. After reinfusion and in late shock, vessel diameters remained constricted. MAP increased to control levels (106 +/- 5 and 101 +/- 4 mmHg, respectively) following re-infusion in both groups but in late shock it decreased until death in the nontolerant group and decreased only minimally (96 +/- 4 mmHg) in the ENDT-T group. The nontolerant group NE ED50 increased from pre-hemorrhage to late shock (p < .05). The ENDT-T group ED50 was unchanged. The bleeding volumes of the two groups were not different. The survival time of the nontolerant group was 234 +/- 36 min, whereas the ENDT-T group all survived and were sacrificed at 427 +/- 30 min. The response to endothelium-dependent ACH vasodilation in late shock was significantly reduced in the saline group but was unchanged in the ENDT-T group. Alpha 1 receptor activity was maintained in both groups. Alpha 2 receptor activity was attenuated pre-hemorrhage and at 240 min post-hemorrhage in ENDT-T rats. In late shock, alpha 2 receptor activity was attenuated in nontolerant rats. The development of endotoxin tolerance prevents the loss of arteriolar responsiveness to NE and ACh. ENDT-T rats have attenuated alpha 2 receptor activity but not alpha 1 receptor activity.

Characterization of npf mutants identifying developmental genes in Physarum

In Physarum polycephalum, uninucleate haploid amoebae develop into macroscopic multinucleate plasmodia. Wild-type, sexual development is triggered when two amoebae carrying different alleles of matA fuse to form a zygote which develops into a diploid plasmodium. Mutations in the matA genetic region give rise to apogamic strains in which a single haploid amoeba can develop into a haploid plasmodium. An essential stage in both sexual and apogamic plasmodium formation is an extended cell cycle in uninucleate cells, which ends with the formation of a binucleate cell by mitosis without cytokinesis. Using a 'brute force' screening method, we have isolated mutants blocked in apogamic plasmodium development. Genetic analysis showed that the mutations we have identified were unlinked to matA, unlike mutations previously identified following an enrichment step. Most of the loci revealed by our screen were represented by only one allele, indicating that further screening should lead to the identification of additional genes required for plasmodium development. Phenotypic analysis showed that different mutants were blocked at different stages of plasmodium formation. Some of the mutations blocking apogamic development at an early stage, close to the start of the long cell cycle, failed to block sexual development in zygotes homozygous for the mutation. Since the two modes of plasmodium formation differ only in the initiation of development, these mutations presumably interfere with the initiation process. In the remaining mutants, in which both sexual and apogamic development were blocked, development first became abnormal towards the end of the long cell cycle. This suggested that the wild-type gene products were required by this time and was consistent with previous evidence that many changes in cellular organization and gene expression occur during the long cell cycle. Each of these mutants showed a different terminal phenotype and some aspects of plasmodium development occurred normally although others were blocked, suggesting that development involves multiple pathways rather than a dependent sequence of events. Phenotypic analysis of double mutants supported this conclusion and also revealed epistatic interactions, presumably due to blocks in the same pathway. In several of the mutants, terminally differentiated cells died by an apoptosis-like mechanism; since this was never observed in vegetative cells, it was presumably triggered by the failure of development. Phenotypic analyses of additional mutants will extend our understanding of the pathways involved in plasmodium development.

Expression of c-kit receptor and its autophosphorylation in immature rat type A spermatogonia

The objective of this study was to examine the expression and activation of the c-kit receptor, a specific receptor for kit ligand (stem cell factor, steel factor), in rat type A spermatogonia. Testes were obtained from 9-day-old rats, decapsulated, and then subjected to sequential enzymatic digestion. The mixture of testicular cell types was then separated by sedimentation velocity at unit gravity. The isolated type A spermatogonia were characterized by light and electron microscopy. They exhibited spherical nuclei containing several nucleoli and associated chromatin clumps and organelles generally in a perinuclear location similar to that found in the in vivo 9-day-old testis. The synthesis of the c-kit receptor by the spermatogonia was established by hybridization of total RNA with a specific cDNA for mouse c-kit receptor. Two mRNA transcripts migrating at 4.8 kb and 12 kb were observed. Localization of the c-kit receptor in the isolated cells was determined by immunocytochemistry using an antibody to c-kit protein. Specific staining for c-kit receptor was observed in the cytoplasm of the isolated type A spermatogonia. Furthermore, the presence of the c-kit receptor protein in the spermatogonia was confirmed by Western blot analysis using the same antibody. The antibody recognized the c-kit receptor at approximately 160 kDa. In an attempt to determine whether this receptor has a functional significance, we examined the effect of kit ligand on the phosphorylation of the c-kit receptor. The c-kit receptor appeared to be constitutively autophosphorylated on tyrosine at low basal levels, and upon stimulation with kit ligand, the amount of phosphorylated protein increased significantly. These observations indicate that kit ligand induces autophosphorylation of the c-kit receptor, which may lead to the activation of other cellular target proteins responsible for spermatogonial proliferation and/or differentiation.

Attenuation of arteriolar alpha 2-adrenoceptor sensitivity during endotoxemia

It is well documented that adrenergic responses after endotoxin (ENDT) administration are greatly reduced. The hypothesis of this study is that either alpha 1- or alpha 2-receptor activity is attenuated and the other receptor type is minimally affected during ENDT shock. Reactivity of the arterioles of left cremaster muscles of male Wistar rats anesthetized with pentobarbital sodium was studied using videomicroscopy. Femoral mean arterial pressure and first-, second-, third-, and fourth-order arteriolar diameters were measured. In group I, the decreases in arteriolar diameter and half-maximal effective dose (ED50) values with increasing phenylephrine concentration (alpha 1-adrenergic receptor agonist) were similar in all four branching orders before and after ENDT. In group II, the decreases in arteriolar diameter with increasing clonidine concentrations (alpha 2-adrenergic receptor agonist) were effectively attenuated by ENDT, and ED50 values were increased above control in all four branching orders. In group III, idazoxan (alpha 2-receptor antagonist) effectively blocked the vasoconstrictor effects of clonidine but did not affect the responses to phenylephrine before or after ENDT in all four arteriolar orders. In group IV, prazosin (alpha 1-adrenergic receptor antagonist) blocked the vasoconstrictor effects of phenylephrine before and after the administration of ENDT. However, vasoconstriction due to clonidine post-ENDT even at maximal dosage (10(-3) M), was greatly attenuated in all four branching orders as in group II. It is concluded that during endotoxemia the reduced adrenergic vasoconstrictor response of cremaster muscle arterioles is the result of attenuated activity of alpha 2-adrenergic receptors with minimal if any effects on alpha 1-adrenergic receptor activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of adenosine-induced coronary vasodilation by block of large-conductance Ca(2+)-activated K+ channels

The aim of the present study was to investigate the contribution of large-conductance calcium-activated potassium (large-conductance KCa) channels to adenosine (Ado)- and nitroprusside-mediated relaxation in small coronary arteries. Canine subepicardial arteries (170 +/- 23 microns at 120 mmHg) were studied as in vitro pressurized vessels. Pressure-diameter experiments showed myogenic tone over a physiological range of pressures. Tone was increased with the thromboxane A2 analogue 9,11-dideoxy-11 alpha,9 alpha-epoxy-methanoprostaglandin F2 alpha (U-46619). Tetraethylammonium (TEA+; 1 mM) significantly inhibited Ado-induced [and by implication, adenosine 3',5'-cyclic monophosphate (cAMP)-induced] relaxations at Ado concentrations ranging from 0.1 to 10 microM with maximal inhibition (61 +/- 8%) at 1 microM Ado. The large-conductance KCa-channel blocker iberiotoxin (IbTX; 0.01-0.1 microM) inhibited Ado-mediated relaxation in a concentration-dependent manner. Inhibition by IbTX increased with increasing vessel pressure (i.e., 45 +/- 12% at 40 mmHg and 83 +/- 20% at 120 mmHg). TEA+ had a minimal effect (8 +/- 3%) on relaxation induced by nitroprusside. Similar results were found with acetylcholine and bradykinin. These results suggest that (in dog coronary arteries with diameter < 200 microns) large-conductance KCa-channel modulation may play a major role in cAMP-mediated relaxation but is not significant in guanosine 3',5'-cyclic monophosphate-mediated relaxation.

On the relation between social information processing and socially competent behavior in early school-aged children

This article tested the hypotheses that (1) children's behavioral competence is a function of patterns of social information processing; (2) processing correlates of behavior occur at each of 5 steps of processing within each of 3 social situations; (3) measures at each step uniquely increment each other in predicting behavior; (4) the relation between processing and behavior is stronger within than across domains; and (5) processing patterns are more sophisticated among older than younger children and the processing-behavior relation is stronger among older than younger children. Videorecorded stimuli were used to assess processing patterns (encoding, interpretational errors and bias, response generation, response evaluation, and enactment skill) in 3 domains (peer group entry, response to provocation, and response to authority directive) in 259 first-, second-, and third-grade boys and girls (ages 6-9 years). Ratings of behavioral competence in each domain were made by peers and teachers. Findings generally supported hypotheses, with the magnitude of relations being modest.

Amplitude enhancement is seen in the cochlear nerve but not at, or before, the afferent synapse

The amplitude of the cochlear nerve compound action potential (CAP) produced by a moderate intensity tonal stimulus (S2) can be enhanced when S2 is preceded by a low intensity S1 of the same frequency. The presence of S1 had no observable influence on the threshold of the CAP to S2. Enhancement was not observed in the cochlear microphonics or summating potentials. Deactivation of the contralateral olivocochlear bundle did not influence enhancement. Tetrodotoxin (TTX) was applied to the round window to block cochlear nerve spike activity, resulting in a residual EPSP-like potential, as described in the guinea pig by Dolan et al. (1989). Kainic acid, in turn, eliminated this EPSP-like response. Even though some differences were found in the responses of the gerbil and their guinea pig preparation to TTX and kainic acid, enhancement was not observed in this residual potential. When enhancement was observed at the level of the CAP, it was observed at brainstem levels. It is suggested that enhancement originates within the cochlear nerve axons.

In vitro reconstitution of a functional peripheral-type benzodiazepine receptor from mouse Leydig tumor cells

The peripheral-type benzodiazepine receptor (PBR) was identified and characterized by its high affinity for two distinct classes of compounds, the benzodiazepines (BZs) and the isoquinolines (IQs). An M(r) 18,000 IQ-binding protein has been identified as the PBR. In this report we isolated and sequenced a 626-base pair cDNA, specifying an open reading frame of 169 amino acid residues with a predicted molecular weight of 18,843, from MA-10 mouse tumor Leydig cells [i.e., mouse peripheral-type benzodiazepine receptor (mPBR)]. Expression of mPBR cDNA in simian virus 40-transformed 3T3 fibroblasts resulted in an increase in the density of both BZ and IQ binding sites. To examine whether the increased drug binding was due to the M(r) 18,000 PBR protein alone or to other constitutively expressed components of the receptor, an in vitro system was developed using recombinant mPBR protein. The mPBR cDNA was inserted in the pMAL-c2 vector downstream from the malE gene, which encodes maltose-binding protein (MBP). Transfection of the recombinant pMAL-c2 in Escherichia coli provided high levels of expression of the MBP-mPBR fusion protein. Purified MBP-mPBR recombinant fusion protein incorporated into liposomes, but not MBP alone, was able to bind IQs but not BZs. Addition of MA-10 mitochondrial extracts to the liposomes resulted in the restoration of BZ binding. The protein responsible for this effect was then purified and identified as the M(r) 34,000 voltage-dependent anion channel protein, which by itself does not express any BZ and IQ binding. These results provide strong evidence that PBR is not a single protein receptor but a multimeric complex in which the IQ binding site is on the M(r) 18,000 subunit and expression of the BZ binding site requires both the M(r) 18,000 and 34,000 voltage-dependent anion channel subunits.

In vitro femoral arterial responses to vasoconstrictor and vasodilator agents in endotoxin shock

The hypothesis for this study is that the decreased arterial response to catecholamines may be due to the effect of endotoxemia on vessel tone. One control ring was taken from one femoral artery of a Wistar rat and after endotoxin (ENDT) infusion (i.v. 6 mg/kg-1 hr.), one ring was removed from the contralateral artery. The post-ENDT rings were tested in four groups which were determined by the mean arterial pressure (MAP) levels at the time of dissection: 100 mmHg (120 min), 80 mmHg (270 min), 60 mmHg (300 min) or 40 mmHg (330 min). KCl, phenylephrine (PHE) and arginine-vasopressin (AVP) dose-response curves (DR) were obtained at a preload of 500 mg which allowed the maximum response in control rings. When compared at 500 mg preload the maximal active response to all agonists post-ENDT was decreased by about 50%. By increasing the preload on the ENDT rings to 800 mg, the active tension became 2.49 times the active tension of the control rings. Length-tension experiments also showed a greater response for post-ENDT rings and a greater preload at maximum response but the ring circumference was the same. In contrast the in vivo femoral artery diameters at 90 min post-ENDT (100 mmHg) were 82.6% of control. Endothelium-dependent relaxation by acetylcholine (ACh) was abolished by ENDT but endothelium-independent relaxation to nitroprusside (NP) was not affected. It is concluded that the resting tone and active tension of femoral artery smooth muscle is increased by ENDT and the decreased in vivo responsiveness to vasoconstrictor agonists may be the result of vessel constriction due to loss of endothelium. The results also suggest that in vitro comparison of vessels in studies of endotoxin shock be done at the same muscle length rather than at the same preload.