Mutation inhibition by beta-estradiol after low doses of gamma-irradiation of mammalian cells

The methodology previously described for measuring mutagenesis has been applied to the study of mutation prevention in immortalized G2 phase human lymphocytes exposed to 25 and 50 cGy of gamma-radiation. Caffeine prevents repair of mutations. Two times 10(-4) M beta-estradiol applied for 2.5 h markedly decreases induced mutations and affects male and female cells similarly. Quantitative measurement of mutagenesis in cells of different individuals and the effect of various agents on mutation yield should be important in prevention of cancer and other mutational disease.

Inadequate control of lipid levels in patients with a previous myocardial infarction

AIM

To access the current lipid management of late survivors of acute myocardial infarction.

METHODS

A systematic follow-up of all survivors who had previously been screened for enrolment into one of three randomised clinical trials in Auckland was undertaken from December 1995 to January 1997. All contacted survivors were asked to answer a questionnaire regarding their current therapy and were invited to undergo venepuncture for a lipid assay.

RESULTS

Of the 1036 patients with acute myocardial infarction screened for enrolment in the three trials there were 984 (95%) who survived 30 days. At a median of 5.5 years (interquartile range 3.2-8.5) follow-up, 641 (86%) survivors agreed to have a fasting lipid test. The mean total cholesterol level was 5.7 +/- 1.1 mmol/L high density lipoprotein cholesterol 1.1 +/- 0.3 mmol/L, low density lipoprotein cholesterol 3.8 +/- 0.9 mmol/L and triglyceride level 1.9 +/- 1.1 mmol/L. Two hundred and seven (32%) patients were treated with a lipid-modifying agent. Four hundred and forty-five (69%) patients had a cholesterol level > or = 5.2 mmol/L 381 (59%) patients had a level > or = 5.5 mmol/L and 72 (11%) patients had a level > or = 7.0 mmol/L of whom 62 patients were not being treated with a lipid-modifying agent. For the 107 patients with coronary artery bypass grafts, the mean cholesterol level was 5.4 mmol/L and the mean low density lipoprotein cholesterol level was 3.7 +/- 0.9 mmol/L, with 57 (53%) patients not being treated with a "statin" or "fibrate".

CONCLUSION

Lipid management is suboptimal in this high risk population of patients post-infarction and greater efforts need to be made to achieve better control. Diet is frequently inadequate in these patients at high risk and statin therapy is indicated.

Visualization and quantification of myocardial mass at risk using three-dimensional contrast echocardiography

OBJECTIVE

Three-dimensional echocardiographic assessment of myocardial ischemia using contrast echocardiography has been hampered by limitations of available contrast agents and analytic software. In the study presented, a three-dimensional perfusion imaging method was evaluated in the porcine model of myocardial ischemia using a novel contrast agent.

METHODS

Three-dimensional echocardiography was performed in eight open-chested pigs before, during and after left anterior descending (six animals) or circumflex (two animals) coronary artery occlusion. The intramyocardial contrast effect was obtained by left atrial injection of Myomap, a deposit contrast agent.

RESULTS

Myocardial opacification was visible in all studies and retained in all three-dimensional datasets. Three-dimensional intensity analysis demonstrated a significant difference, exceeding 20 intensity units in every animal (in 127-level scale), between perfused and non-perfused myocardium. Reperfusion followed by contrast reinjection resulted in homogenous myocardial enhancement. Myocardial mass at risk was clearly delineated in all studies and measured with a mean error of -0.1 +/- 2.0 g against real mass (p = non-significant). Spatial extent of ischemia could be displayed in volume-rendered reconstruction of separate perfusion territories.

CONCLUSIONS

Quantitative analysis of myocardial contrast enhancement from three-dimensional datasets is feasible and allows accurate measurement of myocardial mass at risk.

Comparative study to determine the optimal melatonin dosage form for the alleviation of jet lag

To compare the impact of various dosage forms of melatonin and placebo on jet lag symptoms, 320 volunteers who had flights over 6 to 8 time zones were recruited for a double-blind, randomized, placebo-controlled study. The volunteers received either melatonin 0.5-mg fast-release (FR) formulation, melatonin 5-mg FR formulation, melatonin 2-mg controlled-release (CR) formulation, or placebo. The study medication was taken once daily at bedtime during 4 days after an eastward flight. The volunteers completed the Profile of Mood States (POMS), sleep log, and symptoms questionnaires once daily and the Karolinska Sleepiness Scale (KSS) three times daily prior to departure and during the 4 days of medication intake postflight. A total of 234 (73.1%) participants were compliant and completed the study. The FR melatonin formulations were more effective than the slow-release formulation. The 5-mg FR formulation significantly improved the self-rated sleep quality (p < .05), shortened sleep latency (p < .05), and reduced fatigue and daytime sleepiness (p < .05) after intercontinental flight. The lower physiological dose of 0.5 mg was almost as effective as the pharmacological dose of 5.0 mg. Only the hypnotic properties of melatonin, sleep quality and sleep latency, were significantly greater with the 5.0-mg dose.

Association of enterohemorrhagic Escherichia coli hemolysin with serotypes of shiga-like-toxin-producing Escherichia coli of human and bovine origins

In this study we investigated whether the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene ehxA could be used as an indicator of pathogenicity in Shiga-like-toxin-producing Escherichia coli (SLTEC) isolates. The isolates in a collection of 770 SLTEC strains of human and bovine origins were assigned to group 1 (230 human and 138 bovine SLTEC isolates belonging to serotypes frequently implicated in human disease), group 2 (85 human and 183 bovine isolates belonging to serotypes less frequently implicated in disease), and group 3 (134 bovine isolates belonging to serotypes not implicated in disease). PCR amplification was used to examine all of the SLTEC isolates for the presence of ehxA and the virulence-associated genes eae, slt-I, and slt-II. The percentages of human isolates in groups 1 and 2 that were positive for ehxA were 89 and 46%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive for ehxA were 89, 51, and 52%, respectively. The percentages of human isolates in groups 1 and 2 that were positive for eae were 92 and 27%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive for eae were 78, 15, and 19%, respectively. The frequencies of both ehxA and eae were significantly higher for group 1 isolates than for group 2 isolates. The presence of the ehxA gene was associated with serotype, as was the presence of the eae gene. Some serotypes, such as O117:H4, lacked both eae and ehxA and have been associated with severe disease, but only infrequently. The slt-I genes were more frequent in group 1 isolates than in group 2 isolates, and the slt-II genes were more frequent in group 2 isolates than in group 1 isolates. In a second experiment we determined the occurrence of the ehxA and slt genes in E. coli isolated from bovine feces. Fecal samples from 175 animals were streaked onto washed sheep erythrocyte agar plates. Eight E. coli-like colonies representing all of the morphological types were transferred to MacConkey agar. A total of 1, 080 E. coli isolates were examined, and the ehxA gene was detected in 12 independent strains, only 3 of which were positive for slt. We concluded that the ehxA gene was less correlated with virulence than the eae gene was and that EHEC hemolysin alone has limited value for screening bovine feces for pathogenic SLTEC because of presence of the ehxA gene in bovine isolates that are not SLTEC.

Treponemal specific tests for the serodiagnosis of syphilis. Syphilis and HIV Study Group

OBJECTIVES

To determine the rate of concordance of the Microhemagglutination Assay for Antibodies to T. pallidum (MHA-TP) and the Fluorescent Treponemal Antibody-Absorption test (FTA-ABS) prior to therapy in patients with early stage syphilis and to assess the incidence of and associated risk factors for seroreversion of these treponemal specific tests during the first year after therapy for early syphilis.

DESIGN

Multicenter, prospective, cohort treatment study of patients with early syphilis.

METHODS

Five hundred twenty-five patients were enrolled in a study to evaluate the response of early syphilis to either benzathine penicillin 2.4 million units intramuscularly once or this therapy plus amoxicillin 2 g and probenecid 500 mg orally both three times daily for 10 days. Serologic and clinical follow-up was conducted at intervals over 1 year. MHA-TP and FTA-ABS tests were performed on serologic specimens from each patient visit.

RESULTS

Enrollment specimens showed 5% discordant MHA-TP and FTA-ABS results with 85% of these demonstrating a nonreactive MHA-TP. This occurred most commonly in primary syphilis. In patients who had a 1-year serologic follow-up with FTA-ABS or MHA-TP, seroreversion occurred in 9% and 5% of cases, respectively. No association between HIV-seropositivity and TST seroreversion was demonstrated.

CONCLUSION

The MHA-TP may be less sensitive than the FTA-ABS for identifying patients with primary syphilis. Treponemal specific tests may become nonreactive during the first year after therapy for early syphilis.

A spatio-temporal comparison of semantic and episodic cued recall and recognition using event-related brain potentials

The event-related brain potential (ERP) was used to spatially and temporally map the brain areas active as a function of type of recall (semantic vs. episodic) and episodic retrieval mode (recall vs. recognition) while difficulty of episodic recall was manipulated. ERPs were recorded from 32 scalp sites in 12 subjects, along with behavioral accuracy and recall speed. The results revealed that different but overlapping patterns of ERP activity were elicited during semantic and episodic recall. Recall of both types of information was characterized by ERP activity over left inferior frontal, central, bilateral temporal and posterior inferior brain areas. Compared to semantic recall, episodic recall elicited more activity over the frontal poles and right frontal scalp. Different but overlapping patterns of ERP activity were also found as a function of episodic retrieval mode. While episodic recall and recognition showed similar activity over the frontal poles and central scalp, there was no left inferior frontal activity elicited during recognition and no large, topographically widespread, late positive component (LPC) elicited when the same words were recalled. Manipulation of episodic recall difficulty and analysis of trials when recall failed indicated that these task (i.e., episodic vs. semantic) and retrieval mode (recall vs. recognition) differences in ERP activity were not likely to be due to differences in task difficulty. The results are discussed in terms of processes that the ERP activity may reflect and their similarity to results of PET studies of semantic and episodic retrieval.

Acute inhalation toxicity of neutralized chemical agent identification sets (CAIS) containing agent in chloroform

An acute head-only inhalation study was conducted in rats exposed for 1 h to product solution (wastestream) resultant from the chemical neutralization of Chemical Agent Identification Sets (CAIS) containing agent (sulfur mustard (HD), nitrogen mustard (HN-1) or lewisite (L)) in chloroform. Groups of Sprague-Dawley rats were exposed to varying concentrations (24000, 18000, 12000 or 6000 ppm) of CAIS wastestream. An additional group was exposed to the vehicle (chloroform/t-butanol) only, at a concentration equivalent to the concentration of vehicle at the highest exposure level. Animals were evaluated for toxic effects, including assessment of toxicant-induced alterations to the ocular and respiratory systems. Mortality on exposure to 24000 ppm of test article or to vehicle alone was high. Mortality in the other exposure groups was roughly proportional to the concentration of test article (wastestream). Toxic signs were consistent with exposure to solvent system components (chloroform/t-butanol) and to agent decomposition products/by-products. Incidence and severity of ocular effects were similar in vehicle control and treatment groups. The salient respiratory effect observed was a decreased minute volume, which was also noted in vehicle and treatment groups.

Reducing patient restraint use

Here's an assessment tool to help nurses identify the reasons a patient may require restraint, and find alternative or less-restrictive measures. After using it for 13 months, the staff from one hospital reduced restraint use by 95%-less than 1% of total patient days.

Quality of life and pain in patients with recurrent breast and gynecologic cancer

Pain is a central factor affecting quality of life for the cancer patient. This descriptive study was designed to explore the relationship between pain and several factors affecting quality of life. The factors explored included physical and social functioning, emotional health, and spiritual commitment in women with recurrent breast or gynecologic cancer. Pain frequency, amount, and interference with activities were found to correlate more strongly with objective measures of quality of life (i.e., physical and social functioning) than subjective measures (i.e., psychological or spiritual dimensions).

Genome exposure and regulation in mammalian cells

A method of measurement of exposed DNA (i.e. hypersensitive to DNase I hydrolysis) as opposed to sequestered (hydrolysis resistant) DNA in isolated nuclei of mammalian cells is described. While cell cultures exhibit some differences in behavior from day to day, the general pattern of exposed and sequestered DNA is satisfactorily reproducible and agrees with results previously obtained by other methods. The general pattern of DNA hydrolysis exhibited by all cells tested consists of a curve which at first rises sharply with increasing DNase I, and then becomes almost horizontal, indicating that roughly about half of the nuclear DNA is highly sequestered. In 4 cases where transformed cells (Raszip6, CHO, HL60 and PC12) were compared, each with its more normal homolog (3T3, and the reverse transformed versions of CHO, HL60 and PC12, achieved by dibutyryl cyclic AMP [DBcAMP], retinoic acid, and nerve growth factor [NGF] respectively), the transformed form displayed less genome exposure than the nontransformed form at every DNase I dose tested. When Ca++ was excluded from the hydrolysis medium in both the Raszip6-3T3 and the CHO-DBcAMP systems, the normal cell forms lost their increased exposure reverting to that of the transformed forms. Therefore Ca++ appears necessary for maintenance of the DNA in the more highly exposed state characteristic of the nontransformed phenotype. LiCl increases the DNA exposure of all transformed cells tested. Dextran sulfate and heparin each can increase the DNA exposure of several different cancers. Colcemid prevents the increase of exposure of CHO by DBcAMP but it must be administered before or simultaneously with the latter compound. Measurements on mouse biopsies reveal large differences in exposure in different normal tissues. Thus, the exposure from adult liver cells was greater than that of adult brain, but both fetal liver and fetal brain had significantly greater exposure than their adult counterparts. Exposure in normal human fibroblasts as revealed by in situ nick translation reveals a nuclear distribution pattern around the periphery, around the nucleoli and in punctate positions in the nuclear interior in parts of both S and G1 phases of the cell cycle. The same exposure pattern is duplicated by the pattern of DNA synthesis in S cells. It would appear that these nuclear regions represent positions of special activity. The previously proposed theory of genome regulation in mammalian cells is supported by these findings. The theory proposes that: a) gene activity requires exposure of the given locus followed by action of transcription factors on the exposed genes; b) the fiber system of the cell (cytoskeleton, nuclear fibers, and extracellular fibers) are required for normal exposure; c) active sites for gene expression and replication consist of the nuclear periphery where differentiation genes particularly are exposed; the nucleoli where at least some housekeeping genes are exposed; and possibly also punctate regions in the interior; d) noncoding sequences play a critical role in genome regulation, possibly including the transport of loci to be activated to appropriate exposure transcriptional and replicating locations. Cancer cells have lost specific differentiation gene activities, at least sometimes because of mutation of appropriate exposure genes; at least some protooncogenes and tumor suppressor genes are responsible for exposure and transport of specific differentiation gene loci to their appropriate exposure sites in the nucleus and for inducing exposure.

Influence of sex, seasonality, ethnicity, and geographic location on the components of total energy expenditure in young children: implications for energy requirements

BACKGROUND

There are limited data on the influence of body composition, sex, seasonality, ethnicity, and geographic location on the components of energy expenditure in children.

OBJECTIVE

The objective was to examine the determinants of total energy expenditure (TEE), resting energy expenditure (REE), and activity-related energy expenditure (AEE) in children.

DESIGN

Cross-sectional data from 232 children (4-10 y of age) from 4 ethnic groups (white American, African American, Guatemalan Mestizo, and Native American Mohawk) were examined.

RESULTS

In 104 white children studied in Vermont and Alabama, TEE was significantly higher in spring than in fall, higher in boys than in girls, and higher in children in Vermont (all effects: approximately 0.42 MJ/d, P < 0.05). The significant effect of sex was explained through REE; the influences of season and location were explained through AEE. In all children, there was no effect of sex but a significant effect of ethnicity (P < 0.01) on TEE: a significant effect of sex (P < 0.01) and no effect of ethnicity (P = 0.16) on REE; and no effect of sex and a significant effect of ethnicity on AEE. The significant effects of ethnicity were due to lower values in Guatemalan children. TEE correlated most strongly with weight (r = 0.81) and fat-free mass (r = 0.79-0.81); REE with weight (r = 0.85) and fat-free mass (r = 0.80-0.87); and AEE with maximal oxygen consumption (r = 0.54), fat-free mass (r = 0.50), and fat mass (r = 0.49).

CONCLUSIONS

1) Season and location influenced TEE in children through their effects on AEE, 2) a higher REE in boys was consistent across all groups examined, 3) Guatemalan children had lower TEE due to a lower AEE, 4) body weight may be the best predictor of TEE, and 5) maximal oxygen consumption was the strongest marker of AEE.

Accuracy of three automated compounding systems determined by end-product laboratory testing and comparison with manual preparation

The accuracy of three parenteral nutrient (PN) automated compounding systems and the usefulness of end-product laboratory testing of PN solutions were evaluated. Ten identical PN solutions were prepared by the Nutrimix (Abbott), MicroMacro 23 (Baxa), and Automix-Micromix (Clintec) compounders and manually. Three samples were removed from each of the 40 solutions. Dextrose was measured by high-performance liquid chromatography using a modified sorbitol assay; sodium, potassium, calcium, and magnesium were measured by atomic absorption spectroscopy. Theoretical concentrations of ingredients in the PN solution were adjusted by the actual concentrations in the source containers. The solutions differed significantly in their concentrations of glucose, calcium, and magnesium but not in their concentrations of sodium and potassium. The mean glucose concentrations produced by the manual method and Nutrimix system matched the adjusted theoretical values and by the MicroMacro and Automix-Micromix compounders were within the manufactures' accuracy specifications. The sodium concentrations of all solutions were higher than the adjusted theoretical concentration but within the manufacturers' specifications. Potassium and magnesium concentrations were lower in all solutions than the adjusted theoretical concentrations. Calcium concentrations were above the adjusted theoretical value in all solutions. Differences in compounder accuracy, even when significant, were not consistent and not appreciable. Multiple samples of the same solution should be tested if laboratory analysis is part of quality control.

Interdisciplinary collaboration

This quasiexperimental study investigated interdisciplinary collaboration over a 16-month period on units using different collaborative practice strategies. Measures of collaboration and perceived physician involvement in collaborative practice were completed by 335 licensed staff members working on seven general adult units in an acute care hospital located in an academic medical center. Data were collected at two time points: in 1993 and 1995. A small but statistically significant decline in collaboration was found (p = 0.01) over the 16-month period. Analysis of variance revealed a significant difference (p = 0.03) in collaboration related to the method used to develop collaborative paths. Post hoc Tukey's test indicated that the presence of a case manager without collaborative paths did show higher levels of collaboration (p = 0.05). Regardless of the strategy used, perceived high physician involvement was related to greater collaboration than perceived low involvement with differences increasing over time (p = 0.02). These findings suggest the importance of perceived physician involvement in collaborative practice to interdisciplinary collaboration.

Interaction of cationic diamidines with Leishmania infantum DNA

The interaction of a series of potent leishmanicidal aromatic diamidines resembling pentamidine, was studied with Leishmania infantum DNA and polynucleotides. The diamidines viz., CGP040215A, CGP033829A and CGP039937A, interacted with leishmania DNA as well as with the polynucleotides poly(dA)-poly(dT), poly(dA-dT) and poly(dG-dC). The thermodynamic analysis to determine the association constants and the binding enthalpy pointed toward binding of the diamidines at AT regions of the DNA. The results also indicate that the diamidines bind at the outside of the DNA double helix, probably to the minor groove regions, with hydrogen bonds connecting the amide nitrogen of the diamidine to carbonyl oxygen atoms of thymidine or adenosine bases. However, CGP040215A and CGP033829A, the bisaryl diamidines, showed higher affinity than CGP039937A, the monoaryl diamidine. The spectrophotometric analysis of the interaction of these diamidines to test their effects on the melting temperature of leishmanial DNA suggests non-intercalating binding. The diamidines also showed potent inhibition of DNA polymerase activity of L. infantum extracts in vitro.

Improved quantification of myocardial mass by three-dimensional echocardiography using a deposit contrast agent

The aim of the study was to assess the usefulness of a novel contrast agent in combination with three-dimensional echocardiography for improved mass quantification. Three-dimensional reconstruction of left ventricular myocardium was performed from images obtained with rotational epicardial acquisition in eight open-chested pigs, before and after injection of a deposit contrast agent, Quantison Depot. Three-dimensional echocardiographic myocardial mass values were in excellent agreement with weighted mass (differences -1.6 +/- 5.0 g for end-diastolic frame, -2.8 +/- 4.5 g for end-systolic, 1.0 +/- 1.0 g for end-diastolic with contrast and 0.6 +/- 2.0 g for end-systolic with contrast, p = NS). Left ventricular mass measurements after contrast injection were more accurate and had less measurement variability. In conclusion, myocardial contrast enhancement improves left ventricular mass calculation with three-dimensional echocardiography.

Early noninvasive identification of failed reperfusion after intravenous thrombolytic therapy in acute myocardial infarction

OBJECTIVES

This study sought to evaluate a biochemical approach to the early noninvasive assessment of reperfusion.

BACKGROUND

In patients with an acute myocardial infarction, a rapid noninvasive method of detecting failure of intravenous thrombolytic therapy to restore early Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow in the infarct-related artery (IRA) is needed.

METHODS

Serial blood samples were collected to assay creatine kinase-MB fraction (CKMB mass), cardiac troponin T and myoglobin concentrations in 105 patients with a myocardial infarction who underwent early angiography after intravenous streptokinase. The ratios of the 60- and 90-min concentrations to prethrombolytic values were used to determine an index that could identify failure to achieve TIMI grade 3 flow in the IRA at 90 min.

RESULTS

Significant increases in serum concentrations of markers at 60 min were more likely with TIMI grade 3 flow (59 patients) than with TIMI grade 0 to 2 flow (46 patients). Ratios < or = 5 at 60 min after thrombolysis detected failure to achieve 90-min TIMI grade 3 flow with 92% to 97% sensitivity, 43% to 60% specificity and 63% to 76% positive and 86% to 94% negative predictive values. Ratios < or = 10 at 90 min showed 88% to 95% sensitivity, 49% to 65% specificity and 61% to 69% positive and 86% to 94% negative predictive values for TIMI flow grade < 3. The overall predictive values were thus similar for all three markers.

CONCLUSIONS

In acute myocardial infarction treated with intravenous streptokinase, a simple measurement of increased serum concentrations of CKMB mass, cardiac troponin T or myoglobin at 60 and 90 min can accurately predict failure to achieve TIMI grade 3 flow in the IRA at 90 min.

Evolution of enterohemorrhagic Escherichia coli hemolysin plasmids and the locus for enterocyte effacement in shiga toxin-producing E. coli

This study assessed the diversity of the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene (ehxA) in a variety of Shiga toxin-producing E. coli (STEC) serotypes and the relationship between ehxA types and virulence markers on the locus for enterocyte effacement (LEE). Restriction fragment length polymorphism of the ehxA gene and flanking sequences and of the E. coli attaching and effacing (eae) gene was determined for 79 EHEC hemolysin-positive STEC isolates of 37 serotypes. Two main groups of EHEC hemolysin sequences and associated plasmids, which corresponded to the eae-positive and the eae-negative isolates, were delineated. Comparisons of the ehxA gene sequences of representative isolates of each group showed that this gene and the rest of the EHEC hemolysin operon are highly conserved. Digestion of an ehxA PCR product with the restriction endonuclease TaqI showed a unique restriction pattern for eae-negative isolates and another one for isolates of serotypes O157:H7 and O157:NM. A conserved fragment of 5.6 kb with four potential open reading frames was identified on the EHEC hemolysin plasmid of eae-positive STEC. Phylogenetic analysis of a subset of 27 STEC isolates, one enteropathogenic E. coli isolate, and a K-12 reference isolate showed that eae-positive STEC isolates all belong to a single evolutionary lineage and that the EHEC hemolysin plasmid and the ehxA gene evolved within this lineage without recent horizontal transfer. However, the eae gene and the LEE appear to have been transferred horizontally within this STEC lineage on several occasions. The reasons for the lack of transfer or maintenance of the LEE in other STEC lineages are not clear and require further study.