The Artificial Sweetener, Erythritol, Has Insecticidal Properties Against Pear Psylla (Hemiptera: Psyllidae)

Erythritol is a dietary sweetener that is used for low-calorie or diabetic diets. Although safe for human consumption, erythritol is lethal to certain Dipteran pests, but insecticidal effects of erythritol on phloem-feeding insects have yet to be examined. Our goal was to determine whether erythritol has insecticidal activity against pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae). We first demonstrated that ingestion of erythritol solutions compared with water by pear psylla caused reduced feeding, impaired motor functions, and reduced survival time of adults. We then tested whether foliar treatment of pear leaves with erythritol was also lethal to pear psylla. Foliar treatment of erythritol led to reduced 3-d survival of pear psylla nymphs and adults, and reduced rates of oviposition by pear psylla adults. Psylla adults also preferred to settle on untreated leaves than on erythritol-treated leaves in preference assays. Finally, we conducted field experiments to test whether applications of erythritol provided pear trees with protection against pear psylla under natural field conditions. Those experiments showed a reduction in pear psylla nymphs on erythritol-treated trees compared with untreated trees, but only if the erythritol was completely dissolved into solution by heating. Laboratory trials confirmed the importance of heating. Results of our experiments demonstrate that erythritol is insecticidal to pear psylla nymphs and adults and provide the first report that erythritol is lethal to a phloem-feeding insect. These findings suggest that erythritol may provide a new safe and effective tool for the management of pear psylla.

Inter-blocking: Integrating a Process of Inquiry Mindset into Medical Education

This article was migrated. The article was not marked as recommended. Integrating basic science knowledge with clinical skills is essential for undergraduate medical training. While there are new medical curricula aimed to seamlessly meld these two aspects of medical education, it is unclear how recent developments in cognitive psychology education, such as interleaving, may inform a process of inquiry based curriculum during the early phases of medical education. Here, I offer a hybrid combination of interleaving and blocking theories, or inter-blocking, into an innovative early medical education curriculum centered on investigation by synthesizing strands of basic sciences and clinical skills. This conceptual framework lays the platform for future evidence-based medical and science education research into how modulating different degrees of interleaving and blocking may promote self-motivation, life-long learning, and inclusive communities of learners during the early phases of undergraduate medical education.

The healthcare workers' clinical skill set requirements for a uniformed international response to the Ebola virus disease outbreak in West Africa: the Canadian perspective

Since December 2013, the Zaire Ebola virus disease (EVD) epidemic has ravaged West Africa. In collaboration with the Public Health Agency of Canada, healthcare workers (HCWs) and support staff from the Royal Canadian Medical Services (RCMS) of the Canadian Armed Forces (CAF) were deployed to Kerry Town, Sierra Leone. A total of 79 RCMS personnel deployed over the course of the 6-month mission in collaboration with the British Armed Forces to support efforts in West Africa. The treatment centre was mandated to treat international and local HCWs exposed to the infection. The goal of the Ebola virus disease treatment unit (EVDTU) was to provide care to affected HCWs and a beacon to attract and engage foreign HCWs to work in one of the international non-governmental organisation Ebola treatment centres in Sierra Leone. We focus on the CAF experience at the Kerry Town Ebola treatment unit in Sierra Leone in particular on the various clinical skill sets demonstrated in physicians, nurses and medical technicians deployed to the EVDTU. We outline some of the staffing challenges that arose and suggest that the necessary clinical skills needed to effectively manage patients with EVD in an austere environment can be shared across a small and diverse team of healthcare providers.

Impact of personal protective equipment on clinical output and perceived exertion

BACKGROUND AND AIM

Safe clinical care within Ebola Virus Disease Treatment Units (EVDTUs) mandate the use of personal protective equipment (PPE), comprising a fluid impermeable hooded suit, visor, gloves and rubber boots. The aim of this study was to assess the impact of this PPE on clinical personnel's performance in the EVDTU, Kerry Town, Sierra Leone.

METHODS

An anonymous questionnaire was administered to healthcare professionals (HCPs) entering the EVDTU ward area (Red Zone (RZ)), during a 2-week period to assess perceived exertion using the Borg Rating of Perceived Exertion Scale.

RESULTS

A total of 62 clinical episodes undertaken by 20 HCPs were analysed. There were no episodes of heat illness during the study. HCPs spent a median of 74 (IQR 55-95) minutes within the RZ. Median durations of RZ activity were similar throughout the 24 h period (p=0.22), but Borg scores were significantly higher between 11:00 and 14:59 compared with RZ entry between 15:00 and 10:59, respectively (12 (6-15), n=13; 8 (6-9), n=48; p=0.022). Rates of weight loss per minute spent within the RZ were significantly greater between 11:00 and 14:59 compared with 15:00-10:59, respectively (0.014 (0.009-0.023) kg/min, n=6; 0.007 (0.004-0.013) kg/min, n=37; p=0.037).

CONCLUSIONS

Despite acclimatisation and proactive clinical tasking, HCPs in the EVDTU experienced significantly greater rates of weight loss and perceived exertion scores during the hottest times of the day. These findings should be considered by those planning healthcare facilities for future humanitarian missions where HCPs will provide clinical care in full PPE.

Does concomitant use of paracetamol potentiate the gastroduodenal mucosal injury associated with aspirin? A prospective, randomised, pilot study

BACKGROUND

Paracetamol is commonly prescribed for first-line symptomatic treatment in patients with osteoarthritis and aspirin is often co-administered for cardiovascular prophylaxis. It is not known if an interaction exists between aspirin and paracetamol in regards to gastroduodenal mucosal injury.

AIM

To investigate whether or not co-administered aspirin with paracetamol results in an increased rate of endoscopic gastroduodenal mucosal injury as compared to either agent alone.

METHODS

In this prospective, double-blind, randomised, three-arm, placebo- and active-controlled, parallel-group pilot study healthy adult subjects (18-75 years old) with a normal baseline trans-nasal oesophagogastroduodenoscopy (TN-EGD), received oral paracetamol 4000 mg q.d.s. (n = 21), aspirin 325 mg q.d.s. (n = 19) or paracetamol 4000 mg q.d.s. and aspirin 325 mg q.d.s. (n = 20). Upper gastrointestinal mucosal injury was evaluated after 7 days of treatment with TN-EGD.

RESULTS

The rate of gastric ulcers in subjects receiving paracetamol (0/21, 0%) alone or aspirin (3/19, 16%) or both (2/20, 10%) was not different. There were, however, significantly more subjects with one or more lesions (erosion or ulcer) per subject in the paracetamol and aspirin (16/20, 80%) treated subjects as compared to the aspirin (8/19, 42%, P < 0.001) or the paracetamol (3/21, 14%, P < 0.01) exposed subjects. The mean number of lesions per subject was also greater (7.9 vs. 0.7, P < 0.01) in those treated with aspirin and paracetamol compared to paracetamol alone.

CONCLUSIONS

Co-administration of paracetamol and aspirin was not associated with a significant difference in endoscopic ulcer rates compared to either drug alone. There was a strong signal for increased endoscopic erosions and ulcers in the combined group compared to either aspirin or paracetamol alone.

Clinical trial: maintenance intermittent therapy with rabeprazole 20 mg in patients with symptomatic gastro-oesophageal reflux disease - a double-blind, placebo-controlled, randomized study

BACKGROUND

Optimal long-term management of symptomatic gastro-oesophageal reflux disease (sGERD) patients has not been established.

AIM

To determine the clinical value of maintenance intermittent treatment with rabeprazole 20 mg vs. placebo in patients with sGERD.

METHODS

This multicentre, US study enrolled patients with sGERD (>or=3-month history of GERD symptoms and >or=4 days/week of heartburn during a 2-week placebo run-in) without oesophageal erosions. Patients with complete heartburn control after 4 weeks of open-label rabeprazole 20 mg daily treatment were randomized to 6-month, double-blind, maintenance intermittent treatment (7- to 14-day courses when heartburn recurred) with rabeprazole 20 mg or placebo.

RESULTS

The primary efficacy end point, mean percentage of heartburn-free days, was significantly greater with rabeprazole vs. placebo: 82.58% and 62.17% (ITT; P < 0.0001) [per protocol 86.74% rabeprazole vs. 74.93% placebo (P < 0.0254)]. Compared with placebo group, the rabeprazole group also experienced a significantly higher percentage of heartburn-free daytime (84.06% vs. 63.39%; P < 0.0001) and nighttime (95.41% vs. 90.25%; P = 0.0021) periods, had significantly fewer discontinuations because of insufficient heartburn control (6.3% vs. 36.3%; P < 0.0001) and took fewer antacid tablets daily (0.58 vs. 1.16; P = 0.0021).

CONCLUSION

Intermittent use of rabeprazole may be an effective maintenance treatment strategy for patients with sGERD and warrants further investigation. This trial was registered with http://clinicaltrials.gov under the number NCT00165841.

A comparison between treatment outcomes of stage III and stage IV esophageal squamous cell carcinoma without visceral or bone metastases

e15659

Background: Although classified as end-stage, patients of stage IV esophageal squamous cell carcinoma (SCC) without visceral or bone metastases (nodal stage IV) often have good performance status and are medically fit for curative treatment. The objective of this study was to compare the prognosis of patients of stage III and nodal stage IV. Methods: The retrospective study included patients who were diagnosed esophageal squamous cell carcinoma at Tzu Chi General Hospital from Jan, 2005 to Aug, 2008. Eligible patients must meet the following criteria: (1) stage III or nodal stage IV; (2) underwent esophagectomy or chemoradiation with curative intent; (3) Eastern Cooperative Oncology Group performance status ≤2. The standard order-set of chemotherapy was two monthly cycles of fluorouracil (1,000 mg/m2/24 hours for 4 days) and cisplatin (75 mg/m2 bolus day 1). Radiotherapy dose was 59.4 Gy for concurrent chemoradiation (CCRT) or 54 Gy for adjuvant setting after esophagectomy. Results: Patients characteristics were listed in Table . The median follow-up was 8 months (range: 1∼42 months). In 38 patients underwent definitive CCRT, ten achieved complete response (CR) and 13 achieved partial response. Two-year disease-free survival rate in 28 patients who achieved CR or underwent esophagectomy was 29.9%. Median survival of stage III and nodal IV were 11.5 and 8 months. Two-year overall survival (OS) rate of stage III and nodal IV were 23.9% and 33% (p=0.814). The only significant poor prognostic factor in both univariate and multivariate analyses was tumor length longer than 5 cm. Conclusions: In our study, medically fit patients of nodal stage IV esophageal SCC could achieve OS similar to those of stage III after intensive treatment. The result may indicate the necessity of developing a selection criterion in deciding which nodal stage IV patient should undergo curative treatment. [Table: see text]

No significant financial relationships to disclose.

Cognition following bilateral implants of embryonic dopamine neurons in PD: a double blind study

OBJECTIVES

To determine if bilateral transplantation of embryonic mesencephalic dopamine cells into the putamen of patients with PD significantly affected their cognitive functioning when compared with patients receiving sham surgery and to examine the effect of age on cognitive performance after implantation.

METHODS

Forty patients (19 women, 21 men; age 34 to 75 years) with idiopathic PD of at least 7 years' duration (mean 14 years) who had disabling motor signs despite optimal drug management were randomly assigned to tissue implants or sham craniotomies in a double-blind design. Neuropsychological tests assessing orientation, attention, language, verbal and visual memory, abstract reasoning, executive function, and visuospatial and construction abilities were administered before and 1 year after surgery. Treatment groups did not differ at baseline in demographic, neuropsychological, motor, depression, or levodopa equivalent measures.

RESULTS

Postsurgical change in cognitive performance was not significantly different for real or sham surgery groups. Performance in both groups remained unchanged at follow-up for most measures.

CONCLUSIONS

Embryonic dopamine producing neurons can be implanted safely into the putamen bilaterally without impairing cognition in patients with PD, but within the first year, improved cognition should not be expected.

Involvement of the amino-terminal beta-hairpin of the Aspergillus ribotoxins on the interaction with membranes and nonspecific ribonuclease activity

Ribotoxins are a family of potent cytotoxic proteins from Aspergillus whose members display a high sequence identity (85% for about 150 amino acid residues). The three-dimensional structures of two of these proteins, alpha-sarcin and restrictocin, are known. They interact with phospholipid bilayers, according to their ability to enter cells, and cleave a specific phosphodiester bond in the large subunit of ribosome thus inhibiting protein biosynthesis. Two nonconservative sequence changes between these proteins are located at the amino-terminal beta-hairpin of alpha-sarcin, a characteristic structure that is absent in other nontoxic structurally related microbial RNases. These two residues of alpha-sarcin, Lys 11 and Thr 20, have been substituted with the equivalent amino acids in restrictocin. The single mutants (K11L and T20D) and the corresponding K11L/T20D double mutant have been produced in Escherichia coli and purified to homogeneity. The spectroscopic characterization of the purified proteins reveals that the overall native structure is preserved. The ribonuclease and lipid-perturbing activities of the three mutants and restrictocin have been evaluated and compared with those of alpha-sarcin. These proteins exhibit the same ability to specifically inactivate ribosomes, although they show different activity against nonspecific substrate analogs such as poly(A). The mutant variant K11L and restrictocin display a lower phospholipid-interacting ability correlated with a decreased cytotoxicity. The results obtained are interpreted in terms of the involvement of the amino-terminal beta-hairpin in the interaction with both membranes and polyadenylic acid.

Transplantation of embryonic dopamine neurons for severe Parkinson's disease

BACKGROUND

Transplantation of human embryonic dopamine neurons into the brains of patients with Parkinson's disease has proved beneficial in open clinical trials. However, whether this intervention would be more effective than sham surgery in a controlled trial is not known.

METHODS

We randomly assigned 40 patients who were 34 to 75 years of age and had severe Parkinson's disease (mean duration, 14 years) to receive a transplant of nerve cells or sham surgery; all were to be followed in a double-blind manner for one year. In the transplant recipients, cultured mesencephalic tissue from four embryos was implanted into the putamen bilaterally. In the patients who received sham surgery, holes were drilled in the skull but the dura was not penetrated. The primary outcome was a subjective global rating of the change in the severity of disease, scored on a scale of -3.0 to 3.0 at one year, with negative scores indicating a worsening of symptoms and positive scores an improvement.

RESULTS

The mean (+/-SD) scores on the global rating scale for improvement or deterioration at one year were 0.0+/-2.1 in the transplantation group and -0.4+/-1.7 in the sham-surgery group. Among younger patients (60 years old or younger), standardized tests of Parkinson's disease revealed significant improvement in the transplantation group as compared with the sham-surgery group when patients were tested in the morning before receiving medication (P=0.01 for scores on the Unified Parkinson's Disease Rating Scale; P=0.006 for the Schwab and England score). There was no significant improvement in older patients in the transplantation group. Fiber outgrowth from the transplanted neurons was detected in 17 of the 20 patients in the transplantation group, as indicated by an increase in 18F-fluorodopa uptake on positron-emission tomography or postmortem examination. After improvement in the first year, dystonia and dyskinesias recurred in 15 percent of the patients who received transplants, even after reduction or discontinuation of the dose of levodopa.

CONCLUSIONS

Human embryonic dopamine-neuron transplants survive in patients with severe Parkinson's disease and result in some clinical benefit in younger but not in older patients.

Ribonuclease U2: cloning, production in Pichia pastoris and affinity chromatography purification of the active recombinant protein

RNase U2 is an endoribonuclease secreted by the fungus Ustilago sphaerogena. Its genomic DNA (rnu2), containing an intron of 116 bp, has been isolated and cloned. The corresponding cDNA has also been synthesized. The recombinant RNase U2 was successfully produced in Pichia pastoris, fused to the yeast alkaline phosphatase signal peptide. The recombinant RNase U2, purified by affinity chromatography, contains three extra amino acids at its amino-terminal end and retains the enzymatic and spectroscopic properties of the natural fungal protein.

Hormonal regulation of radioiodide uptake activity and Na+/I- symporter expression in mammary glands

The observation that radioiodide uptake (RAIU) activity, mediated by the Na+/I- symporter (NIS), is significantly increased in lactating breast suggests that RAIU and NIS expression in mammary gland are modulated by hormones involved in active lactation. We showed that both the NIS expression level and RAIU in rat mammary gland are maximal during active lactation compared to those in the mammary glands of virgin and pregnant rats as well as the involuting mammary gland. In the lactating mammary gland, NIS is clustered on the basolateral membrane of alveolar cells as a lesser glycosylated form than NIS in thyroid. The RAIU of lactating mammary gland was partially inhibited by treatment with a selective oxytocin antagonist or bromocriptine, an inhibitor of PRL release. These findings suggest that RAIU and NIS expression in mammary gland are at least in part modulated by oxytocin and PRL. Indeed, we showed that NIS messenger ribonucleic acid level was increased in a dose-dependent manner by oxytocin and PRL in histocultured human breast tumors.

Single amino acid substitutions affecting the specificity of the fungal ribotoxin mitogillin

Mitogillin and related fungal ribotoxins are small basic ribonucleolytic proteins that inhibit protein synthesis by specifically hydrolyzing a single phosphodiester bond in the universally conserved alpha-sarcin/ricin loop (SRL) of large subunit ribosomal RNAs. It was previously shown that mitogillin is a natural derivative of a T1/U2-like ribonuclease with inserted domains that are involved in target selection and specificity. Site-directed mutagenesis was used to substitute single amino acids in the previously identified functional domains Ala1-Tyr24 (B1-L1-B2 domain) and Lys106-Lys113 (L4 region). Examination of the activities of the mutants in the digestion of polyinosinic acid (a ribonuclease substrate) and specific cleavage of the SRL shows that Asn7Ala and Lys111Gln substitutions lead to altered ribonuclease activity and diminished substrate specificity consistent with the proposed functions of these domains.

Ribotoxins are a more widespread group of proteins within the filamentous fungi than previously believed

Alpha-sarcin, restrictocin and mitogillin are the best known members of the family of fungal ribotoxins. In recent years, new members of this family have been discovered and characterised. In this work, we study the occurrence of ribotoxins among different species of fungi. The presence of ribotoxins has been identified in some new species by means of genetic studies, as well as expression and activity assays. The ribotoxin genes have been partially sequenced, and demonstrate a high degree of similarity. These studies demonstrate that these toxins are more widespread than previously considered. This is surprising, considering the ribotoxins are such specific and potent toxins, of unknown biological function. These studies confirm the hypothesis that these proteins are naturally engineered toxins derived from ribonucleases of broad substrate specificity.

Molecular dissection of mitogillin reveals that the fungal ribotoxins are a family of natural genetically engineered ribonucleases

Mitogillin and the related fungal ribotoxins are highly specific ribonucleases which inactivate the ribosome enzymatically by cleaving the 23-28 S RNA of the large ribosomal subunit at a single phosphodiester bond. The site of cleavage occurs between G4325 and A4326 (rat ribosome numbering) which are present in one of the most conserved sequences (the alpha-sarcin loop) among the large subunit ribosomal RNAs of all living species. Amino acid sequence comparison of ribotoxins and guanyl/purine ribonucleases have identified domains or residues likely involved in ribonucleolytic activity or cleavage specificity. Fifteen deletion mutants (each 4 to 8 amino acid deletions) in motifs of mitogillin showing little amino acid sequence homology with guanyl/purine ribonucleases were constructed by site-directed mutagenesis. Analyses of the purified mutant proteins identified those regions in fungal ribotoxins contributing to ribosome targeting and modulating the catalytic activity of the toxin; some of the identified motifs are homologous to sequences in ribosomal proteins and elongation factors. This mutational study of mitogillin together with the recently published x-ray structure of restrictocin (a close relative of mitogillin) supports the hypothesis that the specific cleavage properties of ribotoxins are the result of natural genetic engineering in which the ribosomal targeting elements of ribosome-associated proteins were inserted into nonessential regions of T1-like ribonucleases.

Probing the active site of mitogillin, a fungal ribotoxin

Fungal ribotoxins, such as mitogillin and the related Aspergillus toxins restrictocin and alpha-sarcin, are highly specific ribonucleases, which inactivate the ribosome enzymatically by cleaving the eukaryotic 28S RNA of the large ribosomal subunit at a single phosphodiester bond. The site of cleavage occurs between G4325 and A4326, which are present in a 14-base sequence (the alpha-sarcin loop) conserved among the large subunit rRNAs of all living species. The amino acid residues involved in the cytotoxic activities of mitogillin were investigated by introducing point mutations using hydroxylamine into a recombinant Met-mature mitogillin (mitogillin with a Met codon at the N-terminus and no leader sequence) gene constructed from an Aspergillus fumigatus cDNA clone. These constructs were cloned into a yeast expression vector under the control of the GAL1 promoter and transformed into Saccharomyces cerevisiae. Upon induction of mitogillin expression, surviving transformants revealed that substitutions of certain amino acid residues on mitogillin abolished its cytotoxicity. Non-toxic mutant genes were cloned into an Escherichia coli expression vector, the proteins overexpressed and purified to homogeneity and their activities examined by in vitro ribonucleolytic assays. These studies identified the His-49Tyr, Glu-95Lys, Arg-120Lys and His-136Tyr mutations to have a profound impact on the ribonucleolytic activities of mitogillin. We conclude that these residues are key components of the active site contributing to the catalytic activities of mitogillin.

Comparison of in vitro preconditioning responses of isolated pig and rabbit cardiomyocytes: effects of a protein phosphatase inhibitor, fostriecin

Calcium tolerant pig and rabbit cardiomyocytes were isolated using retrograde aortic perfusion of nominally calcium-free collagenase. Preconditioning protocols used 1 or 3x10-min episodes of ischemic pelleting or pre-incubation with 100 micro M adenosine, followed by a 15-min post-incubation and 180-240-min ischemic pelleting. Control cells were incubated and washed in parallel with the experimental groups. Injury was assessed by determination of cell morphology, trypan blue permeability following osmotic swelling, lactate and HPLC analysis of adenine nucleotides. Preconditioned pig cardiomyocytes had a reduced rate of ischemic contracture, but protection occurred without conservation of ATP. Preconditioned rabbit cardiomyocytes were protected without significant changes in rates of ischemic contracture or ATP depletion. Incubation of ischemic cells with the protein phosphatase inhibitor, fostriecin, at PP2A-selective concentrations (0.1-10 micro M), mimicked preconditioning in both rabbit and pig cardiomyocytes. In rabbits, the KATP channel blocker, 5-hydroxydecanoate (5-HD), did not block preconditioning or fostriecin protection. In the pig, 5-HD blocked both preconditioning and fostriecin protection, with return of the rates of ischemic contracture to control. However, 5-HD was an effective blocker of protection only in early ischemia. Fostriecin mimicked preconditioning in the rabbit and the early responses of the preconditioned pig. Preconditioning appears associated with protein phosphorylation in both the rabbit and the pig, but major pathways leading to protection may differ in the two species.

Crevicular fluid analysis around two failing dental implants: a clinical report

The criteria for monitoring tissue health around endosseous implants remain subjective. Disagreement about which clinical measures of peri-implant health are of diagnostic value continues because of the complexity of the disease process and lack of validated measures of peri-implant health. Crevicular fluid analysis of various inflammatory mediators has been investigated as a means of providing objective criteria of tissue health. In this clinical report, the crevicular fluid levels of interleukin-1 beta (IL-1 beta), an inflammatory cytokine, were used to provide an objective measure of the peri-implant health and the effectiveness of treatment for a patient with two failing implants. The measurement of IL-1 beta may be an important supplement to clinical findings in establishing a diagnosis of peri-implantitis.

Freezing phenomenon in patients with parkinsonian syndromes

Freezing is a common symptom in parkinsonian syndromes, but its association with different causes of parkinsonism as well as with other symptoms has never been investigated. We conducted a database survey of the occurrence of freezing in parkinsonism. Of 347 patients with a clinical diagnosis of parkinsonism other than idiopathic Parkinson's disease and with specific data regarding freezing, 158 patients had freezing (46%). Freezing was significantly associated with progression of the disease as rated on the Hoehn & Yahr scale [odds ratio (OR), 1.69; p < 0.004]. Gender was not a risk factor for the development of freezing. Patients with drug-induced parkinsonism were at a very low risk for developing freezing (p < 0.00001; OR, 0.1). Freezing was found in a high frequency in patients with vascular parkinsonism (57%), normal-pressure hydrocephalus (56%), and generally in the group of patients who had parkinsonism resulting from neurodegenerative diseases (progressive supranuclear palsy, multiple system atrophy, and corticobasal ganglionic degeneration; 45%). Freezing was significantly associated with the presence of dementia, incontinence, and tachyphemia (OR, 2.01, 1.7, and 5.09, respectively).

Load-Insensitive Measurements from an Isolated Perfused Biventricular Working Rat Heart

To determine whether a rat heart model can provide load-insensitive measurements of cardiac function, a recently developed biventricular perfused preparation was tested. Using 29 Sprague-Dawley rat hearts perfused with modified Krebs-Henseleit buffer, ventricles functioned simultaneously with adjustable independent preload (venous reservoirs) and afterload (compliance chambers). Ultrasonic crystal pairs provided continuous left (LV) and right ventricular (RV) short-axis dimensions. LV and RV pressure-length loops (loop area = work) were generated from paired intraventricular pressure and short-axis dimensions. Load-insensitive measurements were obtained from the slopes (elastance) and x-intercepts (L(0)) of regression lines generated from the end-systolic coordinates of these pressure-length loops over ranges of RV and LV preloads. Measurements were made after 15 min of stable function and after 20 min of warm (37 degrees C) ischemia. During perturbations in LV afterload, there were linear changes in dP/dt, but loop work remained relatively unchanged. RV dP/dt and work varied little with physiologic ranges of afterload. Increased RV afterload had little effect on LV function. Ischemia affected LV function more than RV function using these measurements. Elastance, however, increased after ischemia with diastolic 'creep' (increased L(0)) for both ventricles. Load-insensitive and other sophisticated hemodynamic measurements are possible with this new preparation. Copyright 1997 S. Karger AG, Basel

The late-stage diagnosis of colorectal cancer: demographic and socioeconomic factors

OBJECTIVES

This study described factors related to colorectal cancer stage at diagnosis.

METHODS

Logistic regression analyses were used on data from the New York State Tumor Registry and US Census area-level social class indicators.

RESULTS

After the effects of other predictors were controlled for, the odds of late-stage cancer increased as age decreased; women and African Americans were significantly more likely to have late stage than men and Whites; and individuals living in areas of low socioeconomic status (SES) were significantly more likely to be diagnosed at late stage than those living in higher SES areas. Stratified analyses showed that living in a low SES area was the most important determinant of stage for all age, race, gender and source-of-care groups.

CONCLUSIONS

While all populations would benefit from the systematic use of screening socioeconomically disadvantaged groups may also benefit from targeted screening.

Fungal ribotoxins: a family of naturally engineered targeted toxins?

alpha-Sarcin, mitogillin, and restrictocin are small (approximately 17 kDa) basic robosome-inactivating proteins (RIPs) produced by the Aspergilli that catalytically inactivate the large ribosomal subunits of all organisms tested to date. These three fungal ribotoxins act as specific ribonucleases by hydrolyzing one single phosphodiester bond in the universally conserved alpha-sarcin domain of 23-28S rRNAs and are among the most potent inhibitors of protein synthesis known. Previous molecular studies of ribotoxins indicated that they belong to the superfamily of ribonucleases and analysis of the mitogillin gene employing PCR-mediated site-specific mutagenesis suggests that certain domains in ribotoxins, which share homologies with motifs in ribosome-related proteins, may be responsible for the targeting of ribotoxins to the ribosome. The applications of the ribotoxins as tools in research and their uses as therapeutic and diagnostic agents are also reviewed in this paper.

Impact of access and social context on breast cancer stage at diagnosis

This study examined the impact of individual demographic characteristics (age, race/ethnicity, and type of reporting hospital), together with measures of social context, including area of residence socioeconomic status (SES), change in SES, and access to screening (area mammography capacity), on breast cancer stage at diagnosis among New York City residents diagnosed between 1980 and 1985. Three logistic regression models evaluated the impact of individual variables, social context variables, and both classes of variables combined on the outcome of having late-stage (regional or distant) compared to early-stage (local) cancer. The logistic regression models indicated that women aged 50 to 64 years were independently more likely to have late-stage cancer than those younger or older. Controlling for individual and social context variables, African American women were 25 percent more likely than White women to have late-stage breast cancer (p < 0.0001); higher odds seen in the individual model for Hispanic women disappeared after controlling for area SES. In the combined model, women diagnosed from public hospitals were 44 percent more likely to have late-stage disease than those diagnosed in nonpublic settings (p < 0.0001). In both the social context and combined models, area mammography capacity was a significant independent predictor of stage (p = 0.016); area-level SES, but not change in SES, was independently related to late-stage disease (p = 0.002). These data suggest that breast cancer control activities should more actively ensure adequate access to screening, particularly for minorities, populations living in socioeconomically disadvantaged areas, and those cared for in the public sector.

Delayed implantation of demineralized bone powder after local irradiation in rats

Previous studies have shown that osteoinduction is inhibited when demineralized bone powder (DBP) is implanted within 48 hours of local irradiation (i.e., when the acute effects of radiation injury are present). This study sought to determine whether normal osteoinduction can proceed if the implantation of DBP is delayed until 21 days postirradiation. At 21 days, the acute effects of radiation injury are likely to have subsided, but the long-term effects have not yet appeared. Twenty-eight-day-old rats were administered a radiation dose of either 7 or 20 Gy over a localized area of one thigh. The contralateral, nonirradiated thigh served as a control. Demineralized bone powder was subcutaneously implanted 21 days later. Subcutaneous pellets were retrieved at various intervals thereafter (up to Day 45) and were histologically graded for evidence of osteoinduction. No difference in osteoinduction was detected at any time interval in pellets from the 7-Gy-treated sites, compared with controls. Pellets from the 20-Gy-treated sites, however, demonstrated significantly a lower osteoinductive response at each interval. These latter pellets showed small scattered areas of osteoinduction and reduced formation of marrow elements. Thus, although osteoinduction proceeds normally when the implantation of DBP is delayed for 21 days after irradiation with 7 Gy, this is not the case when 20 Gy are administered. Given the absence of gross impairment of tissue vascularity in irradiated sites, it is possible that inhibition of osteoinduction after higher doses of radiation results from permanent damage to mesenchymal precursor cells.

Targeting breast and cervical cancer screening to elderly poor black women: who will participate? The Harlem Study Team

BACKGROUND

Factors associated with participation in breast and cervix cancer screening among elderly black women of low socioeconomic status were determined.

METHODS

Data from a baseline cross-sectional random survey were used together with data on whether screening was subsequently completed or refused. The subjects were a random sample of women attending an urban public hospital primary care clinic for routine medical care with a birth year of 1924 or earlier.

RESULTS

Among the 271 women in the study group, 70% completed screening. Stated intent was the strongest predictor of participation; women who intended to have both mammography and Pap testing were 2.7 times more likely to participate than those who intended to have neither test (95% confidence interval 1.4, 4.9; P < 0.01), controlling for age, insurance status, and level of chronic illness. Women who had more than three chronic illnesses were twice as likely to participate than those with three or fewer illnesses (95% confidence interval 1.1, 3.4 P < 0.02), controlling for the remaining variables. Other variables, including age, history of a recent screening examination, attitudes, or knowledge, were not related to participation. Stated intent was the only variable that predicted compliance with both mammography and Pap smear completion in separate regression models for the individual tests.

CONCLUSION

A high proportion of elderly, socioeconomically disadvantaged black women will participate in cancer screening when it is offered in a primary care setting. Further research on behavioral intentions should be conducted to refine interventions designed to enhance the use of early cancer detection among vulnerable population groups.

Mammography and Papanicolaou smear use by elderly poor black women. The Harlem Study Team

OBJECTIVE

To describe factors related to the use of mammography and Papanicolaou smears in low-income women aged 65 or more years to guide development of future interventions.

DESIGN

A cross-sectional survey.

SETTING AND PATIENTS

Elderly Black women attending a public hospital medical clinic.

MEASUREMENTS

Information obtained in a face-to-face interview of a random sample of patients.

RESULTS

Four-hundred and forty-five women (94%) consented to be interviewed; 74% reported a mammogram, and 85% reported a Papanicolaou smear in the past, although these early-detection tests were not obtained with any regularity after age 65. Concordance between self-reported screening use and blind chart review was more than 90%. The major reasons for non-use of both screening tests were that a physician hadn't recommended them or that the women didn't know they needed them. Levels of knowledge about breast and cervix cancer were low; 68% believed bumping or bruising the breast caused cancer, and only 25% knew that cancer risk increased with advancing age. In logistic regression models, health status, provider type, perceived benefit, life satisfaction, and knowledge of test intervals were each significantly associated with mammogram use. Age, health status, education, perceived susceptibility and benefit, life satisfaction, and knowledge of test intervals were independently related to Pap use (P < .05).

CONCLUSION

This study illustrates that elderly, poor, minority women who are regular health-care users do use mammography and Pap smear screening services. Incorporating screening into routine primary care and physician and patient education could enhance the use of early cancer detection procedures in this age group.

Mathematical analysis of perifusion data: models predicting elution concentration

System models are constructed and analyzed for combined convective flow and for dispersion in distorting concentrations of a chemical signal as it passes through a packed column. We derive general analytical solutions for these models. The results have applications to analyses such as in biological experiments involving hormonal stimulation of perifused cells, elution chromatography, adsorption columns, and studies of groundwater flow. The models reveal that the column distorts an incoming signal (such as a change in solute concentration in the flowing liquid) at the inlet. This distortion is greatest at low values of the Peclet number of the flow and is small at larger values. We explore the effects of the approximations inherent in the mathematical models of the system. Specification of the boundary conditions of the problem are shown to be particularly important. With the use of incorrect models, it is possible to obtain accurate interpolations to data obtained from perfusion experiments. However, the parameters derived (in particular the dispersion constant and the peak concentration of a solute concentration pulse) may be considerably in error. This may lead to errors when these parameter estimates are used to predict results in other experimental situations.

Left ventricular ejection fraction: single-plane and multiplanar transesophageal echocardiography versus equilibrium gated-pool scintigraphy

The relative accuracy and precision of estimating left ventricular ejection fraction (EF) in dogs were assessed by two-dimensional transesophageal echocardiography (2D-TEE) and by three-dimensional transesophageal echocardiographic (3D-TEE) imaging and reconstruction. This assessment was accomplished by comparing each echocardiographic method to a gated equilibrium blood pool radionuclide (RN) standard. By using both correlation and regression analysis, 2D-TEE performed reasonably well in estimating RNEF (correlation coefficient [r] = 0.80, slope = 1.01, intercept = 6.37, standard error of the estimate [SEE], 8.98), but not as well as 3D-TEE (r = 0.86, slope = 0.83, intercept = 3.38, SEE, 5.74). Using Altman and Bland's methods of comparison analysis, it was found that 2D-TEE overestimated RNEF by 7% (standard deviation [SD], 8.8). This degree of overestimation was not consistent across the range of measurement. In contrast, 3D-TEE slightly underestimated RNEF by less than 3% and showed less variability (SD, 6.0). The accuracy of the 3D-TEE determinations was not dependent on the magnitude of EF. Additionally, a significantly higher proportion of the 2D-TEE measurements (0.30) compared with the 3D-TEE measurements (0.10) differed from RN values by more than 10% (P = 0.009, McNemar's test). At the clinically important low end of the EF range (RNEF less than or equal to 35%), 2D-TEE may be expected (with 95% confidence) to be within -15% to +28% EF of reference values, whereas 3D-TEE can be expected to be within -8% to +5% EF relative to RN.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascorbic acid stimulates production of glycosaminoglycans in cultured fibroblasts

The effect of ascorbic acid on collagen synthesis is well characterized. Proteoglycans and their attached glycosaminoglycans are components of the extracellular matrix closely associated with collagen fibers. We examined whether ascorbic acid also plays a role in glycosaminoglycan production. Synthesis and deposition of glycosaminoglycans into the extracellular matrix and secretion into the media were followed in human skin fibroblasts cultured in the presence and absence of ascorbic acid. Specific glycosaminoglycans were identified and quantitated by differential enzyme digestion, ion-exchange column chromatography, and cellulose-acetate electrophoresis. No major qualitative changes in glycosaminoglycans were observed. However, quantitatively, synthesis of glycosaminoglycans increased 30 to 90%, and deposition into the extracellular matrix increased 80% in the presence of ascorbic acid. This effect was only in part secondary to decreased levels of collagen, and the diminished capacity of underhydroxylated collagen to bind proteoglycans. The effect of ascorbic acid on extracellular macromolecules is thus more pervasive than previously assumed.

Measurement of left ventricular ejection fraction and volumes with three-dimensional reconstructed transesophageal ultrasound scans: comparison to radionuclide and thermal dilution measurements

A transesophageal, ultrasonic cardiac imaging probe was built that incorporated a mechanism for changing the angle of the imaging plane of a conventional phased array in a precise and known manner. This probe was used to acquire an angular spatial sequence of two-dimensional images of the left ventricular cavity over a series of cardiac cycles by sweeping the imaging plane through it stepwise. The endocardial borders of these images were manually outlined off-line and the application of a three-dimensional reconstruction algorithm was then used to compute the left ventricular end-diastolic and end-systolic volumes and ejection fraction. A study was conducted with seven anesthesized dogs to compare ultrasonic determinations by this method with determinations and measurements made using radionuclide and thermal dilution methods. Comparison of 33 ejection fractions, measured by the ultrasonic volume method and by the gated blood pool radionuclide approach, yielded a correlation coefficient of 0.87 and a standard error of the estimate of 5.7% measured over a range of 10% to 58% (average, 40%). Comparison of the ultrasonically measured volumes with those calculated from stroke volume (derived from thermal dilution cardiac output measurement) and ejection fraction (measured by radionuclide technique) produced a correlation coefficient of 0.92 and a standard error of the estimate of 10.3 mL over a range of 18 to 130 mL (average, 56 mL). The accuracy of volume and ejection fraction measurements with this new ultrasonic method seems comparable to that of other currently used clinical approaches such as radionuclide and angiography.

Beneficial effects of cocarboxylase in the treatment of experimental myocardial infarction in dogs

Cocarboxylase, or thiamine pyrophosphate, is an essential coenzyme in the catabolism of pyruvate. The authors evaluated the effects of a stable cocarboxylase solution in the treatment of an experimentally created acute myocardial infarction in 14 healthy mongrel dogs. The left anterior descending artery was ligated for 60 minutes and data were collected at the following points: A) prior to ligation, B) 15 minutes after ligation, C) 30 minutes after ligation, and D) 60 minutes after ligation. In one group (Group II), cocarboxylase (150 mgm/kg) was given systematically via a central line 15 minutes and 45 minutes after ligation, while in Group I an equal amount of D5W was given. Hemodynamic data include heart rate, systolic and mean arterial pressure, pulmonary wedge pressure, right arterial pressure, and cardiac output. Myocardial O2 consumption was determined by the method of Rooke and Feigl. Electrocardiographic data were also monitored throughout the experiment. In both groups, preligation (point A) hemodynamic data were similar. In Group II, there were beneficial hemodynamic changes versus Group I (expressed as percentage recovery of hemodynamic performance from preligation) at points C and D, with significant (P less than 0.05) decreases in heart rate, increased stroke volume, decreased systemic vascular resistance, and decreased myocardial O2 consumption. EKG criteria also showed improvement in Group II versus Group I. In conclusion, this experiment suggests that cocarboxylase may be beneficial to ischemic canine myocardium by virtue of its favorable systemic hemodynamic effects.

A quantitative in vitro assay of polymorphonuclear leukocyte migration through human amnion membrane utilizing 111in-oxine

A modified amnion chemotaxis assay is described for measurement of polymorphonuclear leukocyte(s) (PMNL) migration (random and directed) into a viable membrane. The primary modifications are the use of 111In-oxine-labelled PMNL and replacement of the nitrocellulose 'trap' filter with a type I collagen sponge. The modifications resulted in four important benefits: the quantification of PMNL migration was simplified; reader subjectivity was eliminated; the information gained of the migration process was enhanced; and the assay time was decreased. The amnion chemotaxis assay with the modifications reported should provide the means of evaluating several aspects of the inflammatory response of PMNL.

Effects of anoxia and ischemia on protein synthesis in perfused rat hearts

The effect of ischemia on synthesis of myocardial proteins was investigated using a model of perfusion in which low levels of coronary flow were provided to paced hearts worked against a closed aortic outflow tract. These conditions rapidly produced ischemia and ventricular failure, as evidence by reduced coronary flow, increased left atrial pressure, and decreased pressure development. Protein synthesis was inhibited in a subsequent 1-hour period, during which a minimal coronary flow was maintained by retrograde perfusion. ATP, GTP, and creatinine phosphate were depleted in ischemic hearts and AMP accumulated. Production and accumulation of lactate within the tissue increased, whereas palmitate uptake was inhibited. The inhibition of protein synthesis was not associated with reduced levels of intracellular amino acids. During ischemia, decreased levels of ribosomal subunits as compared to paced or unpaced aerobic hearts suggested that peptide chain elongation was slow relative to initiation. Provision of insulin further reduced subunit levels but did not increase protein synthesis, suggesting that the hormone did not prevent inhibition of peptide chain elongation in energy-poor hearts.

Effects of hypophysectomy, growth hormone, and thyroxine on protein turnover in heart

Cardiac atrophy following hypophysectomy was accompanied by decreased heart content of RNA and polysomes and increased levels of ribosomal subunits, suggesting that protein synthesis was restricted by a reduced supply of ribosomes and an imbalance between rates of peptide-chain initiation and elongation. During perfusion in vitro, provision of palmitate restored the normal balance between rates of initiation and elongation but protein synthesis was lower in hearts of hypophysectomized than normal rats, reflecting the lower RNA content of hearts from hormone-deficient animals. After the period of atrophy had passed, or after treatment with growth hormone and thyroxine, heart RNA content and rates of protein synthesis were equal to or greater than those found in normal hearts. When plasma levels of amino acids, glucose, fatty acids, and insulin, and rates of beating and ventricular pressure development observed in normal and hypophysectomized rats were simulated during in vitro perfusion, hearts from hormone-deficient rats had reduced rates of protein synthesis but unaltered rates of degradation. Cathepsin D activity in heart homogenates (+ Triton X-100) was elevated during cardiac atrophy when expressed per g of tissue but not when expressed per heart.

Effect of insulin on protein turnover in heart muscle

The effect of insulin on turnover of protein was investigated in isolated perfused rat hearts. The hormone lowered intracellular levels of nine amino acids and reduced or abolished net release of 10 amino acids and ammonia. The extent of the insulin effect on protein degradation was investigated by estimating the rate of dilution of the specific radioactivity of the free phenylalanine pool. Insulin concentrations greater than 200 microunits per ml reduced protein degradation and net phenlylalanine release. Protein degradation was estimated more directly by inhibiting reincorporation of nonradioactive phenylalanine from protein with cycloheximide. Addition of the inhibitor increased the estimated rates about 50%, but the magnitude of the hormone effect was similar. The latency of lysosomal enzymes in control and insulin-treated hearts was assessed by measuring activities of beta-acetylglucosaminidase and cathepsin D in heart homogenates in the presence and absence of Triton X-100. Perfusion with insulin-free buffer increased the activities assayable without detergent, but did not change total activities of these enzymes. Insulin decreased activities assayable without detergent and increased activities sedimenting in the 10-5 times g pellet. These studies showed that insulin restricted the rate of protein degradation in the isolated perfused rat heart. Concomitantly, the latency of lysosomal enzymes was increased when the hormone was provided.