Highly Atherogenic Lipid Particles are Associated with Preeclampsia After Successful Fertility Treatment for Obese Women who have Unexplained Infertility

Atherogenic dyslipidemia-before or during pregnancy-may contribute to preeclampsia and subsequent cardiovascular disease risk. We performed a nested case-control study to further understand dyslipidemia associated with preeclampsia. The cohort consisted of participants in the randomized clinical trial "Improving Reproductive Fitness Through Pretreatment with Lifestyle Modification in Obese Women with Unexplained Infertility" (FIT-PLESE). FIT-PLESE was designed to study the effect of a pre-fertility treatment 16-week randomized lifestyle intervention program (Nutrisystem diet + exercise + orlistat vs. training alone) on improvement in live birth rate among obese women with unexplained infertility. Of the 279 patients in FIT-PLESE, 80 delivered a viable infant. Maternal serum was analyzed across five visits: before and after lifestyle interventions and also at three pregnancy visits (16, 24, and 32 weeks gestation). Apolipoprotein lipids were measured in a blinded fashion using ion mobility. Cases were those who developed preeclampsia. Controls also had a live birth but did not develop preeclampsia. Generalized linear and mixed models with repeated measures were used to compare the mean lipoprotein lipid levels of the two groups across all visits. Complete data were available for 75 pregnancies, and preeclampsia developed in 14.5% of the pregnancies. Cholesterol/high-density lipoprotein (HDL) ratios (p < 0.003), triglycerides (p = 0.012), and triglyceride/HDL ratios, all adjusted for BMI, were worse in patients with preeclampsia (p < 0.001). Subclasses a, b, and c of highly atherogenic, very small, low-density lipoprotein (LDL) particles were higher during pregnancy for the preeclamptic women (p < 0.05). Very small LDL particle subclass d levels were significantly greater only at 24 weeks (p = 0.012). The role of highly atherogenic, very small LDL particle excess in the pathophysiology of preeclampsia awaits further investigation.

First record of Trichophyton benhamiae isolated from domestic cats in Russia

We report a first case of Trichophyton benhamiae isolation from domestic cats in Russia. Genetically affiliated to European strains T. benhamiae were deposited in NCBI. T. benhamiae strains formed zonal cream-colored colonies, with reversum pigmentation ranging from intensive yellow to orange-brown in one and orange-brown to chocolate in the second strain. Mycelium is colorless, hyphae are septated, rapidly aging with the formation of arthrospores and microconidia. The formation of macroconidia was recorded after 48 hours. A favorable outcome of treatment was recorded after two weeks.

Spatiotemporal image quality of virtual reality head mounted displays

Virtual reality (VR) head mounted displays (HMDs) require both high spatial resolution and fast temporal response. However, methods to quantify the VR image quality in the spatiotemporal domain when motion exists are not yet standardized. In this study, we characterize the spatiotemporal capabilities of three VR devices: the HTC VIVE, VIVE Pro, and VIVE Pro 2 during smooth pursuit. A spatiotemporal model for VR HMDs is presented using measured spatial and temporal characteristics. Among the three evaluated headsets, the VIVE Pro 2 improves the display temporal performance using a fast 120 Hz refresh rate and pulsed emission with a small duty cycle of 5%. In combination with a high pixel resolution beyond 2 k [Formula: see text] 2 k per eye, the VIVE Pro 2 achieves an improved spatiotemporal performance compared to the VIVE and VIVE Pro in the high spatial frequency range above 8 cycles per degree during smooth pursuit. The result demonstrates that reducing the display emission duty cycle to less than 20% is beneficial to mitigate motion blur in VR HMDs. Frame rate reduction (e.g., to below 60 Hz) of the input signal compared to the display refresh rate of 120 Hz yields replicated shadow images that can affect the image quality under motion. This work supports the regulatory science research efforts in development of testing methods to characterize the spatiotemporal performance of VR devices for medical use.

Evaluation Challenges for the Application of Extended Reality Devices in Medicine

Augmented and virtual reality devices are being actively investigated and implemented for a wide range of medical uses. However, significant gaps in the evaluation of these medical devices and applications hinder their regulatory evaluation. Addressing these gaps is critical to demonstrating the devices' safety and effectiveness. We outline the key technical and clinical evaluation challenges discussed during the US Food and Drug Administration's public workshop, "Medical Extended Reality: Toward Best Evaluation Practices for Virtual and Augmented Reality in Medicine" and future directions for evaluation method development. Evaluation challenges were categorized into several key technical and clinical areas. Finally, we highlight current efforts in the standards communities and illustrate connections between the evaluation challenges and the intended uses of the medical extended reality (MXR) devices. Participants concluded that additional research is needed to assess the safety and effectiveness of MXR devices across the use cases.

[Small salivary glands in the paratonsillar space in children]

Was to study the changes in the small salivary glands in chronic tonsillitis and paratonsillar abscess in children. A histological examination of the palatine tonsils of 22 children aged 5 to 14 years old who had a paratonsillar abscess and 18 children suffering from chronic tonsillitis was carried out. Fragments of small salivary glands, located both superficially, in the mucous membrane between the stratified squamous non-keratinizing epithelium and the lymphoid tissue of the palatine tonsils, and between the muscles of the amygdala were found in 42 of the 80 (52.5%) tonsils studied. Along with the unchanged glandular structure, 26 (61.9%) samples revealed areas of destruction foci in small salivary glands with signs of inflammatory and compensatory regenerative activity. The presence of separate interlobular ducts of the salivary glands with pronounced periductal lymph - macrophage infiltration was noted. The subepithelial lymph-macrophage infiltrates found in the lamina propria are associated with the exit of the excretory ducts of the salivary glands to the surface of the mucous membrane. Many thin-walled veins are surrounded by perivascular lymphocellular infiltrates. The inflammatory and post-inflammatory changes in the small salivary glands revealed by us in children with chronic tonsillitis do not exclude their participation in the pathogenesis of paratonsillitis. At the same time, inflammation in the salivary gland can be both primary, as a result of its infection with live microorganisms from the tissues of the tonsil, and secondary, due to the compression of the excretory ducts by the edematous tissue of the tonsil in acute tonsillitis.

Transverse chromatic aberration in virtual reality head-mounted displays

We demonstrate a method for measuring the transverse chromatic aberration (TCA) in a virtual reality head-mounted display. The method relies on acquiring images of a digital bar pattern and measuring the displacement of different color bars. This procedure was used to characterize the TCAs in the Oculus Go, Oculus Rift, Samsung Gear, and HTC Vive. The results show noticeable TCAs for the Oculus devices for angles larger than 5° from the center of the field of view. TCA is less noticeable in the Vive in part due to off-axis monochromatic aberrations. Finally, user measurements were conducted, which were in excellent agreement with the laboratory results.

A Systematic Review of Exposure to Bisphenol A from Dental Treatment

INTRODUCTION

Dental composite restorations and dental sealants containing bisphenol A glycidyl methacrylate (BisGMA) are commonly used materials in dentistry. Bisphenol A (BPA) is used to manufacture BisGMA and can be a by-product in BisGMA-based dental materials. BPA is an endocrine-disrupting chemical that may affect reproductive, psychological, cognitive, and endocrine-related health. We conducted a systematic review of clinical studies that measured urinary BPA (uBPA) concentrations before and after dental treatment to evaluate the extent to which individuals are exposed to BPA from dental treatment.

METHODS

Eligibility included studies that measured uBPA concentrations before and after dental treatment with any type of resin-based dental material. We searched PubMed, Cochrane, Web of Science, Virtual Health Library, Science Direct, ProQuest, and Clinical Trials with no date or language restrictions to identify published studies. We summarized eligible studies across participant characteristics, amount of treatment, and time of follow-up measures. Because methods of measuring uBPA varied, our primary outcome was the direction and percentage change between baseline and 24 h posttreatment and at later time points as available.

RESULTS

We identified 1,190 abstracts and 7 eligible studies: 4 in children and 3 in adults. In all studies, BPA concentrations increased 24 h after treatment. The 2 studies with the largest sample sizes found statistically significant increases >40% in uBPA concentrations at 24 h posttreatment (both P values <0.01). The 1 study to examine uBPA concentrations beyond 1 mo posttreatment found that concentrations returned to baseline by 14 d after treatment and remained at baseline 6 mo after treatment.

CONCLUSIONS

Our findings suggest that uBPA concentrations increase 24 h after dental treatment. One study showed that uBPA concentrations return to baseline by 14 d. Additional research is needed to determine the magnitude of change from pre- to post-dental treatment and the trajectory of uBPA concentrations posttreatment.

KNOWLEDGE TRANSFER STATEMENT

BPA is an endocrine-disrupting chemical that may have negative human health effects. Our findings suggest that urinary BPA concentrations increase in the short term after dental treatment. The extent to which such an increase may affect the health of patients remains an open question, particularly since there are no established thresholds for safety or harm related to BPA exposure.

[The significance of antistreptolysin O characteristics for the determination of indications for tonsillectomy in the children]

The objective of the present work was to evaluate the diagnostic significance of the measurement of the antistreptolysin O (ASLO) titers in the children presenting with chronic tonsillitis for determining the indications for tonsillectomy. The study included 54 patients at the age varying from 4 to 17 years who had undergone bilateral tonsillectomy for the treatment of chronic tonsillitis. The diagnosis was confirmed by the results of the histological study of the removed amygdalae. Prior to surgery, all the patients had been subjected to the bacteriological investigation of the smears taken from the surface of the palatal tonsils. The titers of antistreptolysin O in the serum were determined with the use of the kinetic nephelometric technique before, 6 and 12 months after the surgical intervention. The results of the measurements were treated using the Statzilla software package (version 3.2, R Foundation for Statistical Computing, Vienna, Austria). Streptococcus pyogenes (group A) was identified only in 7 (13%) patients. The initially enhanced content of ASLO ranging from 273 to 1880 IU/ml was documented in 42 (77.7%) of the 54 patients. Twelve patients had the ASLO titers within the normal limits (from 13 to 124 IU/ml). The removal of palatal tonsils resulted in a significant decrease of the ASLO titers in the patients who had presented with the initially enhanced content of antistreptolysin O (p < 0.05); nevertheless, their ASLO titers remained higher than the normal values in 69% and 82% of the patients examined within 6 and 12 months after the surgical intervention, respectively. The patients who had exhibited the high levels of antistreptolysin O during the preoperative period did not experience normalization of this parameter after surgery. It is concluded, taking into account the absence of correlation between the enhancement of serum antistreptolysin O titers and the presence of group A beta-chemolytic Streptococci (BCSA), that the result of the measurement of ASLO titers can not be considered as a valid indication for tonsillectomy in the children.

[Proinflammatory cytokine content in the saliva of children suffering from chronic tonsillitis]

INTRODUCTION

We have examined 92 children aged between 6 and 15, suffering from chronic tonsillitis (CT). Tumor necrosis factor (TNF-α) and interleukin 1β and 6 (IL-1β and IL-6) contents have been defined in saliva. The control set comprised 17 healthy children. Cytokine content was defined with the enzyme multiplied immunoassay sets (Vektor Best Ltd., Russia) by enzyme-linked immunosorbent assay. The statistic analysis and data processing were carried out with statistic analysis programs (version 3.2, R Foundation for Statistical Computing, Vienna, Austria).

RESULTS

The content of cytokines TNF-α, IL-1, IL-6 in CT children's saliva was high against the healthy children, yet the statistically significant differences were only noted for IL-6. In the CT group the median value of this factor (12.5) was significantly higher than in the control set (6.72) (p=0.01 in Mann-Whitney assessment). IL-6 was chosen as the basic factor for the mathematic model; its combinations in the form of a multi-factor logistic regression were given consideration. From out of the three possible models there was just one that had all the coefficients statistically significantly different from zero (TNF-α - IL-6). It was chosen as the basic diagnostic model for chronic tonsillitis. The created model's sensitivity is 80.4%, while its specificity is 82.4%.

DISCUSSION

The revealed IL-6 dominance in saliva at CT can be is attributable to permanent antigenic challenge characteristic of the toxic allergic CT since, as previously shown, there are living proliferating microorganisms in the palatal tonsil tissues and their blood- and lymph vessels at CT.

CONCLUSION

The conducted ROC-analysis has demonstrated high sensitivity and specificity of the mathematical model, which enabled us to recommend determination of IL-6 in the saliva of the children suffering from CT as an additional diagnostic criterion.

Dental Pathology of the California Bobcat (Lynx rufus californicus)

Skulls from 277 California bobcats (Lynx rufus californicus) were examined macroscopically and by radiography. The majority of the skulls were from adult animals (79.8%). The skulls were from 128 male (46.2%) and 114 female (41.2%) animals and gender was unknown for the remainder. The majority (95.6%) of teeth were present for examination. Only 16 teeth were identified as absent congenitally and 15 of these were incisor teeth. Teeth with abnormal morphology were rare (0.5%). The two most common abnormalities were unusually large crowns of the maxillary first molar teeth and bigemination of the mandibular incisor teeth. Teeth with an abnormal number of roots were uncommon (n = 68). Sixty-three teeth had abnormal roots, mostly the presence of two roots instead of one for the maxillary first molar tooth. The most prevalent dental lesions found in the California bobcat were attrition/abrasion (85.2%), periodontitis (56.0%) and tooth fractures (50.9%). Less common dental lesions were endodontal disease (n = 114 teeth) and tooth resorption (n = 73 teeth).

Mapping of Mcs30, a new mammary carcinoma susceptibility quantitative trait locus (QTL30) on rat chromosome 12: identification of fry as a candidate Mcs gene

Rat strains differ dramatically in their susceptibility to mammary carcinogenesis. On the assumption that susceptibility genes are conserved across mammalian species and hence inform human carcinogenesis, numerous investigators have used genetic linkage studies in rats to identify genes responsible for differential susceptibility to carcinogenesis. Using a genetic backcross between the resistant Copenhagen (Cop) and susceptible Fischer 344 (F344) strains, we mapped a novel mammary carcinoma susceptibility (Mcs30) locus to the centromeric region on chromosome 12 (LOD score of ∼8.6 at the D12Rat59 marker). The Mcs30 locus comprises approximately 12 Mbp on the long arm of rat RNO12 whose synteny is conserved on human chromosome 13q12 to 13q13. After analyzing numerous genes comprising this locus, we identified Fry, the rat ortholog of the furry gene of Drosophila melanogaster, as a candidate Mcs gene. We cloned and determined the complete nucleotide sequence of the 13 kbp Fry mRNA. Sequence analysis indicated that the Fry gene was highly conserved across evolution, with 90% similarity of the predicted amino acid sequence among eutherian mammals. Comparison of the Fry sequence in the Cop and F344 strains identified two non-synonymous single nucleotide polymorphisms (SNPs), one of which creates a putative, de novo phosphorylation site. Further analysis showed that the expression of the Fry gene is reduced in a majority of rat mammary tumors. Our results also suggested that FRY activity was reduced in human breast carcinoma cell lines as a result of reduced levels or mutation. This study is the first to identify the Fry gene as a candidate Mcs gene. Our data suggest that the SNPs within the Fry gene contribute to the genetic susceptibility of the F344 rat strain to mammary carcinogenesis. These results provide the foundation for analyzing the role of the human FRY gene in cancer susceptibility and progression.

Early stroke risk and ABCD2 score performance in tissue- vs time-defined TIA: a multicenter study

OBJECTIVES

Stroke risk immediately after TIA defined by time-based criteria is high, and prognostic scores (ABCD2 and ABCD3-I) have been developed to assist management. The American Stroke Association has proposed changing the criteria for the distinction between TIA and stroke from time-based to tissue-based. Research using these definitions is lacking. In a multicenter observational cohort study, we have investigated prognosis and performance of the ABCD2 score in TIA, subcategorized as tissue-positive or tissue-negative on diffusion-weighted imaging (DWI) or CT imaging according to the newly proposed criteria.

METHODS

Twelve centers provided data on ABCD2 scores, DWI or CT brain imaging, and follow-up in cohorts of patients with TIA diagnosed by time-based criteria. Stroke rates at 7 and 90 days were studied in relation to tissue-positive or tissue-negative subcategorization, according to the presence or absence of brain infarction. The predictive power of the ABCD2 score was determined using area under receiver operator characteristic curve (AUC) analyses.

RESULTS

A total of 4,574 patients were included. Among DWI patients (n = 3,206), recurrent stroke rates at 7 days were 7.1%(95% confidence interval 5.5-9.1) after tissue-positive and 0.4% (0.2-0.7) after tissue-negative events (p diff < 0.0001). Corresponding rates in CT-imaged patients were 12.8% (9.3-17.4) and 3.0% (2.0-4.2), respectively (p diff < 0.0001). The ABCD2 score had predictive value in tissue-positive and tissue-negative events (AUC = 0.68 [95% confidence interval 0.63-0.73] and 0.73 [0.67-0.80], respectively; p sig < 0.0001 for both results, p diff = 0.17). Tissue-positive events with low ABCD2 scores and tissue-negative events with high ABCD2 scores had similar stroke risks, especially after a 90-day follow-up.

CONCLUSIONS

Our findings support the concept of a tissue-based definition of TIA and stroke, at least on prognostic grounds.

Use of genomic data in risk assessment case study: II. Evaluation of the dibutyl phthalate toxicogenomic data set

An evaluation of the toxicogenomic data set for dibutyl phthalate (DBP) and male reproductive developmental effects was performed as part of a larger case study to test an approach for incorporating genomic data in risk assessment. The DBP toxicogenomic data set is composed of nine in vivo studies from the published literature that exposed rats to DBP during gestation and evaluated gene expression changes in testes or Wolffian ducts of male fetuses. The exercise focused on qualitative evaluation, based on a lack of available dose-response data, of the DBP toxicogenomic data set to postulate modes and mechanisms of action for the male reproductive developmental outcomes, which occur in the lower dose range. A weight-of-evidence evaluation was performed on the eight DBP toxicogenomic studies of the rat testis at the gene and pathway levels. The results showed relatively strong evidence of DBP-induced downregulation of genes in the steroidogenesis pathway and lipid/sterol/cholesterol transport pathway as well as effects on immediate early gene/growth/differentiation, transcription, peroxisome proliferator-activated receptor signaling and apoptosis pathways in the testis. Since two established modes of action (MOAs), reduced fetal testicular testosterone production and Insl3 gene expression, explain some but not all of the testis effects observed in rats after in utero DBP exposure, other MOAs are likely to be operative. A reanalysis of one DBP microarray study identified additional pathways within cell signaling, metabolism, hormone, disease, and cell adhesion biological processes. These putative new pathways may be associated with DBP effects on the testes that are currently unexplained. This case study on DBP identified data gaps and research needs for the use of toxicogenomic data in risk assessment. Furthermore, this study demonstrated an approach for evaluating toxicogenomic data in human health risk assessment that could be applied to future chemicals.

Prospective follow-up oral food challenge in food protein-induced enterocolitis syndrome

OBJECTIVES

To determine tolerance rates to cow's milk and soy and to suggest guidelines for follow-up oral food challenges (FU-OFCs) in infantile food protein-induced enterocolitis syndrome (FPIES).

METHODS

The authors analysed the data of 23 patients with infantile FPIES who underwent two or more FU-OFCs and were followed up until over 2 years of age. The first FU-OFCs were performed at 6 months of age, and patients were randomly allocated to cow's milk (n = 11) or soy (n = 12) challenge starting groups. Second and third FU-OFCs were performed at 2-month intervals in a crossed and switched-over manner.

RESULTS

Tolerance rates to cow's milk and soy were 27.3% and 75.0% at 6 months of age, 41.7% and 90.9% at 8 months and 63.6% and 91.7% at 10 months, respectively. Patients outgrew cow's milk and soy intolerance at age 20 and 14 months.

CONCLUSIONS

In infantile FPIES, the first FU-OFC should be performed with soy at 6-8 months of age and cow's milk FU-OFC should be conducted at over 12 months of age. Infants with FPIES were observed to outgrow food sensitivities during the first 2 years of life.

AMP-activated protein kinase: a core signalling pathway in the heart

Over the past decade, AMP-activated protein kinase (AMPK) has emerged as an important intracellular signalling pathway in the heart. Activated AMPK stimulates the production of ATP by regulating key steps in both glucose and fatty acid metabolism. It has an inhibitory effect on cardiac protein synthesis. AMPK also interacts with additional intracellular signalling pathways in a coordinated network that modulates essential cellular processes in the heart. Evidence is accumulating that AMPK may protect the heart from ischaemic injury and limit the development of cardiac myocyte hypertrophy to various stimuli. Heart AMPK is activated by hormones, cytokines and oral hypoglycaemic drugs that are used in the treatment of type 2 diabetes. The tumour suppressor LKB1 is the major regulator of AMPK activity, but additional upstream kinases and protein phosphatases also contribute. Mutations in the regulatory gamma2 subunit of AMPK lead to an inherited syndrome of hypertrophic cardiomyopathy and ventricular pre-excitation, which appears to be due to intracellular glycogen accumulation. Future research promises to elucidate the molecular mechanisms responsible for AMPK activation, novel downstream AMPK targets, and the therapeutic potential of targeting AMPK for the prevention and treatment of myocardial ischaemia or cardiac hypertrophy.

Permeate flux inflection due to concentration polarization in crossflow membrane filtration: A novel analytic approach

A convection-diffusion equation for membrane filtration is analytically solved assuming fast crossflow velocity of a simple shear flow tangential to the membrane surface. In the direction normal to the membrane surface, solute concentration varies in a partially exponential and partially power-wise manner. The permeate flux in an asymptotic limit is proportional to the inverse square root of the distance from the inlet of the membrane channel. Osmotic pressure due to retained solutes on the membrane surface controls the profile of the permeate flux, which undergoes an inflection along the tangential direction if applied pressure is more than four times the feed osmotic pressure.

Comparative genomics of susceptibility to mammary carcinogenesis among inbred rat strains: role of reduced prolactin signaling in resistance of the Copenhagen strain

To elucidate the molecular basis for differential susceptibilities to mammary carcinogenesis, we compared the transcriptomes of normal mammary glands from pubescent female rats of the resistant Copenhagen (Cop) strain with those of the susceptible Fischer 344 (F344), August x Copenhagen Irish (ACI), Buffalo/N (Buf/N), Wistar-Furth (WF) strains and F1 (Cop x F344) progeny (F1). Gene expression profiles in mammary tissue within each rat strain were remarkably similar, indicating that gene expression was determined by genetic background. We next identified the subset of genes that were differentially expressed in all susceptible strains relative to the resistant Cop strain. Among these, the messenger RNAs encoding prolactin (Prl) and its cell surface receptor were significantly elevated in all susceptible strains. The expression levels of several Prl-regulated genes were also significantly elevated, indicating the presence of increased Prl signaling in mammary glands of all susceptible strains. Pathway analysis of gene expression profiles further identified the Prl-activated Jak/STAT-signaling pathway among the pathways that most distinguished sensitive rat strains from the resistant Cop rat. To test the hypothesis that reduced levels of the Prl signaling in mammary tissue partially contributed to the genetic resistance to mammary carcinogenesis, we used the neuroleptic drug, perphenazine, to transiently elevate serum Prl levels in the Cop strain. Whereas Cop rats are resistant to N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis, approximately 5% of pubescent Cop females treated with perphenazine and NMU exposure developed mammary adenocarcinomas with latencies comparable with those of sensitive strains. Together, these finding indicated that in the rat, the molecular mechanisms underlying genetic susceptibility to mammary carcinogenesis include de-regulation of Prl signaling.

Childhood acute lymphocytic leukemia and perspectives on risk assessment of early-life stage exposures

Recognition that children are a potentially susceptible subpopulation has led to the development of child-specific sensitivity factors. Establishing reliable sensitivity factors in support of risk assessment of early-life stage exposures can be aided by evaluating studies that enhance our understanding both of the biological basis of disease processes and the potential role of environmental exposures in disease etiology. For these reasons, we evaluated childhood acute lymphocytic leukemia (ALL) studies from the point of view of mechanism and etiology. ALL is the most common form of childhood cancer proposed to result from a prenatal primary event and a postnatal second event. This multi-stage model is supported by the observation that chromosomal translocations/fusion genes (e.g., TEL-AML1) involved in producing ALL are detected at birth (prenatal event), and a postnatal event (e.g., TEL deletion) is required for disease manifestation. It appears that a proportion of ALL cases are the result of environmental exposures, in which case preconceptional, prenatal, and postnatal stages are likely to be critical exposure windows. To this end, we recognized postnatal infection-related risk factors as potential candidates associated with the ALL second event. Additionally, we discuss use of ALL-associated fusion genes and genetic polymorphisms, together or separately, as indicators of ALL susceptibility and increased risk. The possibility of using fusion genes alone as biomarkers of response is also discussed because they can serve as predictors of key events in the development of a mode of action (a sequence of key events, starting with interaction of an agent with a cell, ultimately resulting in cancer formation) for particular environmental exposures. Furthermore, we discuss use of an initiated animal model for ALL, namely transgenic mice with TEL-AML1 expression, for exploring mechanisms by which different classes of environmental exposures could be involved in inducing the postnatal step in ALL formation.

Evaluation of the Corneal Effects of Topical Ophthalmic Fluoroquinolones Using In Vivo Confocal Microscopy

PURPOSE

To compare the effects of several fluoroquinolone antibiotics on the corneal epithelium and stroma using in vivo confocal microscopy.

METHODS

Five antibiotic solutions were evaluated: 1) 0.3% ofloxacin (Oflox) solution with 0.005% benzalkonium chloride (BAC); 2) 0.3% gatifloxacin (Gati) solution with 0.005% BAC; 3) 0.3% ciprofloxacin (Cipro) solution with 0.006% BAC; 4) 0.5% levofloxacin (Levo) with 0.005% BAC; and 5) 0.5% moxifloxacin (Moxi) solution with no BAC. Preservative-free artificial tears (Tears) were used as a control. New Zealand white rabbits were used for this study (six per solution group). Ten days prior to exposure to any solution, central corneal epithelial thickness and stromal thickness were measured using in vivo confocal microscopy through focusing. Images of the superficial epithelium were also acquired. Both eyes of each rabbit then received one drop of the assigned solution six times the first day and then four times per day for 6 days. On day 7, in vivo confocal microscopy was repeated.

RESULTS

A significant decrease in epithelial thickness was induced by 7 days of exposure to Levo, Gati, Oflox, and Cipro (P < 0.05, two-way repeated-measures ANOVA, Tukey test). Tears and Moxi, which do not contain BAC, did not induce significant changes in epithelial thickness. No significant changes in stromal thickness were detected (P = 0.266), and no keratocyte activation was observed for any of the solutions evaluated.

CONCLUSION

We have previously used confocal microscopy to establish a correlation between epithelial thinning (due to superficial cell loss) and slight ocular irritation. The results of this study suggest that Moxi induces less damage to the corneal epithelium than other antibiotic solutions, perhaps because it does not contain BAC.

Ligation of high-melting-temperature 'clamp' sequence extends the scanning range of rare point-mutational analysis by constant denaturant capillary electrophoresis (CDCE) to most of the human genome

Mutations cause or influence the prevalence of many diseases. In human tissues, somatic point mutations have been observed at fractions at or below 4/10,000 and 5/100,000 in mitochondrial and nuclear DNA, respectively. In human populations, fractions for the multiple alleles that code for recessive deleterious syndromes are not expected to exceed 5 x 10(-4). Both nuclear and mitochondrial point mutations have been measured in human cells and tissues at fractions approaching 10(-6) using constant denaturant capillary electrophoresis (CDCE) coupled with high-fidelity PCR (hifiPCR). However, this approach is only applicable to those target sequences (approximately 100 bp) juxtaposed with a 'clamp', a higher-melting-temperature sequence, in genomic DNA; such naturally clamped targets represent approximately 9% of the human genome. To open up most of the human genome to rare point-mutational analysis, a high-efficiency DNA ligation procedure was recently developed so that a clamp could be attached to any target of interest. We coupled this ligation procedure with prior CDCE/hifiPCR and achieved a sensitivity of 2 x 10(-5) in human cells for the first time using an externally attached clamp. At this sensitivity, somatic mutations, each representing an anatomically distinct cluster of cells (turnover unit) derived from a mutant stem cell, may be detected in a series of tissue samples, each containing as many as 5 x 10(4) turnover units. Additionally, rare inherited mutations may be scanned in pooled DNA samples, each derived from as many as 10(5) persons.

High-efficiency DNA ligation for clamp attachment without polymerase chain reaction

We coupled ligation with mass action to achieve high-efficiency clamp attachment without polymerase chain reaction (PCR). Using a 10-fold molar excess of a GC-rich clamp of synthesized and hybridized oligonucleotides, we achieved the maximum clamp-ligation efficiency in which the clamp was ligated to >95% of 10(10)-10(12) restriction ends of a PCR-amplified fragment. The maximum efficiency was confirmed by ligating the clamp to 10(11)-10(12) restriction ends of human genomic DNA. Our approach can be added to a constant denaturant capillary electrophoresis (CDCE)-based method of analyzing rare point mutants at fractions as low as 10(-6); such mutants appear as small copy numbers in the initial samples. This CDCE-based method alone is applicable to only those DNA sequences juxtaposed with an internally occurring clamp of a higher melting temperature in genomic DNA. Since such sequences represent 9% of the human genome, the addition of clamp ligation significantly increases the scanning range for the human genome without reducing the initial mutant copy numbers. Furthermore, clamp ligation/attachment without PCR prevents PCR-created mutants from interfering with rare mutational analysis. In addition to those applications seeking high-efficiency DNA ligation, our approach can be generally applied to ligation of restriction ends.

Liver and circulating NK1.1(+)CD3(-) cells are increased in infection with attenuated Salmonella typhimurium and are associated with reduced tumor in murine liver cancer

An attenuated (DeltacyA, Deltacrp) strain of Salmonella typhimurium (chi4550) containing a gene for human IL-2 (chi4550pIL2) reduces hepatic tumor burden when orally inoculated into mice with liver cancer; however, wild-type S. typhimurium is also associated with cancer regression. Therefore, experiments were designed to clarify the invasiveness and the anti-tumor properties of three strains of S. typhimurium. S. typhimurium chi4550pIL2, chi4550, or wild type (WT) was incubated with mature Caco-2 and HT-29 enterocytes, and S. typhimurium internalization was assessed. For infectivity experiments, mice were orally inoculated with saline or 10(9)S. typhimurium chi4550pIL2, chi4550, or WT; 48 h later mice were sacrificed for analysis of cecal bacteria and S. typhimurium translocation to mesenteric lymph nodes. For experiments involving tumor implantation, four groups were studied: saline control, tumor alone, chi4550pIL2+tumor, and chi4550+tumor. Mice were orally inoculated with saline or S. typhimurium and underwent laparotomy 24 h later with 5 x 10(4) MCA38 murine adenocarcinoma cells injected into the spleen. On day 14, liver tumors were counted and peripheral blood and hepatic lymphocyte populations were analyzed by FACScan. Attenuated S. typhimurium exhibited decreased internalization by cultured enterocytes and decreased infectivity after oral inoculation. Mice treated with chi4550pIL2 or chi4550 had fewer liver tumors and increased populations of hepatic and circulating NK1.1(+)CD3(-) lymphocytes compared to mice treated with saline (P < 0.01). These data suggest that attenuated S. typhimurium may have an application as an anti-tumor agent.

A slow wave investigation of working memory biases in mood disorders

Mood-congruent working memory biases were examined in a delayed matching to sample paradigm using the slow wave (SW) event-related brain potential (ERP) component. Mood-congruent working memory biases, indexed by SW amplitudes, were demonstrated among individuals experiencing a major depressive episode (MDE) and nondepressed controls but not individuals with dysthymia. However, analyses of symptom severity demonstrated that those with dysthymia exhibited significantly less negative SW amplitudes with increasing depressive mood severity, whereas individuals with major depression demonstrated more negative SW amplitudes with increasing depressive mood severity. These results are discussed in the context of diagnostic specificity for cognitive biases associated with working memory of mood-disordered individuals.

Wnt receptors and Wnt inhibitors are expressed in gradients in the developing telencephalon

The caudomedial margin of the medial pallium, known as the cortical hem, expresses several Wnt genes that have been shown to be crucial for cortical development. We examined the expression of members of the Frizzled (mFz) family of Wnt receptors and the Secreted Frizzled Related Protein (SFRP) family of Wnt inhibitors during telencephalic development. We found that mFz-5 and mFz-8 are specifically expressed in the neocortical neuroepithelium and excluded from the hippocampal neuroepithelium in early telencephalic development, whereas mFz-9 and mFz-10 have expression domains confined to the medial pallium. In addition, SFRP-1 and SFRP-3 are expressed in opposing anterolateral to caudomedial gradients within the telencephalic ventricular zone throughout corticogenesis.

Pax-6 regulates expression of SFRP-2 and Wnt-7b in the developing CNS

Wnt signaling regulates a wide range of developmental processes such as proliferation, cell migration, axon guidance, and cell fate determination. In this report, we studied the expression of secreted frizzled related protein-2 (SFRP-2), which codes for a putative Wnt inhibitor, in the developing nervous system. SFRP-2 is expressed in several discrete neuroepithelial domains, including the diencephalon, the insertion of the eminentia thalami into the caudal telencephalon, and the pallial-subpallial boundary (PSB). We also noted that Wnt-7b expression was similar to SFRP-2 expression. Because many of these structures are disrupted in Pax-6 mutant mice, we examined SFRP-2 and Wnt-7b expression in the forebrains of Pax-6 Sey/Sey mice. We found that Pax-6 mutants lack SFRP-2 expression in the PSB and diencephalon. Interestingly, Pax-6 mutants also lack Wnt-7b expression in the PSB, but Wnt-7b expression in the diencephalon is preserved. Furthermore, in the spinal cord of Pax-6 mutants, SFRP-2 and Wnt-7b expression was greatly reduced. Our results suggest that by virtue of its apposition to Wnt-7b expression, SFRP-2 may modulate its function, particularly at boundaries such as the PSB, and that changes in Wnt signaling contribute to the phenotype of Pax-6 mutants.

Constitutively activating mutation in WASP causes X-linked severe congenital neutropenia

The Wiskott-Aldrich syndrome protein (WASP; encoded by the gene WAS) and its homologs are important regulators of the actin cytoskeleton, mediating communication between Rho-family GTPases and the actin nucleation/crosslinking factor, the Arp2/3 complex. Many WAS mutations impair cytoskeletal control in hematopoietic tissues, resulting in functional and developmental defects that define the X-linked Wiskott-Aldrich syndrome (WAS) and the related X-linked thrombocytopenia (XLT). These diseases seem to result from reduced WASP signaling, often through decreased transcription or translation of the gene. Here we describe a new disease, X-linked severe congenital neutropenia (XLN), caused by a novel L270P mutation in the region of WAS encoding the conserved GTPase binding domain (GBD). In vitro, the mutant protein is constitutively activated through disruption of an autoinhibitory domain in the wild-type protein, indicating that loss of WASP autoinhibition is a key event in XLN. Our findings highlight the importance of precise regulation of WASP in hematopoietic development and function, as impairment versus enhancement of its activity give rise to distinct spectra of cellular defects and clinical phenotypes.

A slow wave investigation of working memory biases in mood disorders

Mood-congruent working memory biases were examined in a delayed matching to sample paradigm using the slow wave (SW) event-related brain potential (ERP) component. Mood-congruent working memory biases, indexed by SW amplitudes, were demonstrated among individuals experiencing a major depressive episode (MDE) and nondepressed controls but not individuals with dysthymia. However, analyses of symptom severity demonstrated that those with dysthymia exhibited significantly less negative SW amplitudes with increasing depressive mood severity, whereas individuals with major depression demonstrated more negative SW amplitudes with increasing depressive mood severity. These results are discussed in the context of diagnostic specificity for cognitive biases associated with working memory of mood-disordered individuals.

Clostridium difficile toxins A and B can alter epithelial permeability and promote bacterial paracellular migration through HT-29 enterocytes

Clostridium difficile toxins A and B are the widely recognized etiologic agents of antibiotic-associated diseases ranging from diarrhea to pseudomembranous colitis. We hypothesized that C. difficile toxins may alter intestinal epithelial permeability and facilitate bacterial penetration of the intestinal epithelial barrier. Experiments were designed to clarify the effects of C. difficile toxins A and B on the flux of inert particles across HT-29 enterocyte monolayers, and to correlate these results with bacteria-enterocyte interactions. In all experiments, mature, confluent HT-29 cultures were preincubated 16 h with toxin A or B (1-100 ng/mL). To study alterations in epithelial permeability, toxin-treated enterocytes were incubated with 5 pM solutions of 10- and 40-kD inert dextran particles. Toxin A, but not toxin B, was associated with increased dextran flux through enterocyte monolayers. To study bacteria-enterocyte interactions, toxin-treated enterocytes were incubated with 10(8) Salmonella typhimurium, Proteus mirabilis, or Escherichia coli. Although numbers of internalized bacteria were generally unaffected, both toxins were associated with increased bacterial adherence, as well as increased bacterial transmigration through enterocyte monolayers. Bacterial transmigration was significantly greater using toxin A- compared to toxin B-treated enterocytes, consistent with the observation that dextran flux was significantly greater using toxin A- compared to toxin B-treated enterocytes. Thus intestinal colonization with toxigenic C. difficile may facilitate bacterial penetration of the intestinal epithelium by a mechanism involving increased permeability of the intestinal epithelial barrier.

Autoinhibition and activation mechanisms of the Wiskott-Aldrich syndrome protein

The Rho-family GTPase, Cdc42, can regulate the actin cytoskeleton through activation of Wiskott-Aldrich syndrome protein (WASP) family members. Activation relieves an autoinhibitory contact between the GTPase-binding domain and the carboxy-terminal region of WASP proteins. Here we report the autoinhibited structure of the GTPase-binding domain of WASP, which can be induced by the C-terminal region or by organic co-solvents. In the autoinhibited complex, intramolecular interactions with the GTPase-binding domain occlude residues of the C terminus that regulate the Arp2/3 actin-nucleating complex. Binding of Cdc42 to the GTPase-binding domain causes a dramatic conformational change, resulting in disruption of the hydrophobic core and release of the C terminus, enabling its interaction with the actin regulatory machinery. These data show that 'intrinsically unstructured' peptides such as the GTPase-binding domain of WASP can be induced into distinct structural and functional states depending on context.

Clostridium difficile toxins may augment bacterial penetration of intestinal epithelium

BACKGROUND

Clostridium difficile can be recovered from many high-risk hospitalized patients receiving broad-spectrum antibiotic therapy. Clostridium difficile toxins A and B have been associated with increased intestinal permeability in vitro and there is growing evidence that increased intestinal permeability may be a common mechanism whereby enteric bacteria penetrate the intestinal epithelium.

HYPOTHESIS

Clostridium difficile-induced alterations in the intestinal barrier facilitate microbial penetration of the intestinal epithelium, which in turn facilitates the translocation of intestinal bacteria.

DESIGN

Mature Caco-2 enterocytes were pretreated with varying concentrations of toxin A or toxin B followed by 1 hour of incubation with pure cultures of either Salmonella typhimurium, Escherichia coli, or Proteus mirabilis. The effects of toxins A and B on enterocyte viability, cytoskeletal actin, and ultrastructural topography were assessed using vital dyes, fluorescein-labeled phalloidin, and scanning electron microscopy, respectively. The toxins' effects on bacterial adherence and bacterial internalization by cultured enterocytes were assessed using enzyme-linked immunosorbent assay and quantitative culture, respectively. Epithelial permeability was assessed by changes in transepithelial electrical resistance and by quantifying paracellular bacterial movement through Caco-2 enterocytes cultivated on permeable supports.

RESULTS

Neither toxin A nor toxin B had a measurable effect on the numbers of enteric bacteria internalized by Caco-2 enterocytes; however, both toxins were associated with alterations in enterocyte actin, decreased transepithelial electrical resistance, and increased bacterial adherence and paracellular transmigration.

CONCLUSION

Clostridium difficile toxins A or B may facilitate bacterial adherence and penetration of the intestinal epithelial barrier.

Concentration Polarization of Interacting Solute Particles in Cross-Flow Membrane Filtration

A theoretical approach for predicting the influence of interparticle interactions on concentration polarization and the ensuing permeate flux decline during cross-flow membrane filtration of charged solute particles is presented. The Ornstein-Zernike integral equation is solved using appropriate closures corresponding to hard-spherical and long-range solute-solute interactions to predict the radial distribution function of the solute particles in a concentrated solution (dispersion). Two properties of the solution, namely the osmotic pressure and the diffusion coefficient, are determined on the basis of the radial distribution function at different solute concentrations. Incorporation of the concentration dependence of these two properties in the concentration polarization model comprising the convective-diffusion equation and the osmotic-pressure governed permeate flux equation leads to the coupled prediction of the solute concentration profile and the local permeate flux. The approach leads to a direct quantitative incorporation of solute-solute interactions in the framework of a standard theory of concentration polarization. The developed model is used to study the effects of ionic strength and electrostatic potential on the variations of solute diffusivity and osmotic pressure. Finally, the combined influence of these two properties on the permeate flux decline behavior during cross-flow membrane filtration of charged solute particles is predicted. Copyright 1999 Academic Press.

Cementless implant composition and femoral stress. A finite element analysis

Proximal atrophy and thigh pain are recognized problems with some cementless femoral stems in total hip arthroplasty. It is thought that reduced femoral stress from alterations in load transfer caused by an intramedullary stem contributes to proximal femoral atrophy. An increase in flexural rigidity and bone stress near the stem tip is thought to contribute to thigh pain. A three-dimensional finite element analysis study was performed to calculate stresses in the proximal femur and bone near the stem tip before and after implantation of a collared, proximally coated, cementless femoral prosthesis. The influence of prosthetic material was examined by changing implant composition from cobalt chrome to titanium alloy and leaving all other parameters constant. Femoral stress was increased twofold immediately below the collar with the titanium implant compared with the cobalt chrome. However, the proximal femoral stress in the titanium implanted model was still 1/10 that in the corresponding region of the unimplanted femur model. At the stem tip, as much as a 30% reduction in femoral stress was seen with the titanium stem compared with the cobalt chrome. These findings suggest biomechanical evidence of an advantage for titanium as an implant material compared with cobalt chrome for cementless femoral stems.

Multiple regions of ligand discrimination revealed by analysis of chimeric parathyroid hormone 2 (PTH2) and PTH/PTH-related peptide (PTHrP) receptors

PTH and PTH-related peptide (PTHrP) bind to the PTH/PTHrP receptor and stimulate cAMP accumulation with similar efficacy. Only PTH activates the PTH2 receptor. To examine the structural basis for this selectivity, we analyzed receptor chimeras in which the amino terminus and third extracellular domains of the two receptors were interchanged. All chimeric receptors bound radiolabeled PTH with high affinity. Transfer of the PTH2 receptor amino terminus to the PTH/PTHrP receptor eliminated high-affinity PTHrP binding and significantly decreased activation by PTHrP. A PTH/PTHrP receptor N terminus modified by deletion of the nonhomologous E2 domain transferred weak PTHrP interaction to the PTH2 receptor. Introduction of the PTH2 receptor third extracellular loop into the PTH/PTHrP receptor increased the EC50 for PTH and PTHrP, while preserving high-affinity PTH binding and eliminating high-affinity PTHrP binding. Similarly, transfer of the PTH/PTHrP receptor third extracellular loop preserved high-affinity PTH binding by the PTH2 receptor but decreased its activation. Return of Gln440 and Arg394, corresponding residues in the PTH/PTHrP and PTH2 receptor third extracellular loops, to the parent residue restored function of these receptors. Simultaneous interchange of wild-type amino termini and third extracellular loops eliminated agonist activation but not binding for both receptors. Function was restored by elimination of the E2 domain in the receptor with a PTH/PTHrP receptor N terminus and return of Gln440/Arg394 to the parent sequence in both receptors. These data suggest that the amino terminus and third extracellular loop of the PTH2 and PTH/PTHrP receptors interact similarly with PTH, and that both domains contribute to differential interaction with PTHrP.

An unusual over-gravid female of Enterobius vermicularis recovered from a child

An unusual over-gravid female of Enterobius vermicularis was recovered from a 15-month old child by cello-tape anal swab. The patient resided in Inchon and complained of severe anal itching. The worm measured 7.8 mm in length and 0.5 mm in width, and retained typical morphologic features of E. vermicularis such as cephalic alae and a sharply pointed posterior end. In this gravid female, peculiarly, the uterus was tremendously distended, and about 99% of the whole body length was completely packed with a great number of eggs. Other internal organs were difficult to observe. This paper describes a peculiar over-gravid female of E. vermicularis.

Compartment model for measuring myocardial oxygen consumption using [1-11C]acetate

Although [1-11C]acetate has been validated as a PET tracer for myocardial oxygen consumption (MVO2) in animals and humans, mono- and biexponential fitting of the tissue time-activity curve yields only estimates of MVO2. This study attempts to develop and validate a simple tracer kinetic model in vivo for estimation of regional MVO2.

METHODS

Twenty-seven experiments were performed in 12 anesthetized dogs with [1-11C]acetate and serial PET images under different MBF and MVO2 (baseline, ischemia, xylazine, dobutamine and dipyridamole). Estimates of MVO2 were obtained from dynamic [1-11C]acetate PET and model fitting. MBF was measured by radiolabeled microspheres, and MVO2 was calculated by the Fick method using arterial and coronary blood samples.

RESULTS

The proposed model fitted equally well for all study conditions with a multiple correlation coefficient of 0.985 +/- 0.026. Estimated MVO2 correlated linearly with measured MVO2 (y = 0.033 + 0.690x, r = 0.92, s.e. of estimates = 0.020).

CONCLUSION

This study indicates that MVO2 can be assessed with PET and [1-11C]acetate over a wide range with a simple tracer kinetic model.

Reproducibility of measurements of regional resting and hyperemic myocardial blood flow assessed with PET

PET with 13N-ammonia permits the noninvasive quantification of myocardial blood flow (MBF) in humans. The present study was done to assess the reproducibility of quantitative blood flow measurements at rest and during pharmacologically induced hyperemia in healthy individuals.

METHODS

Thirty healthy volunteers (26 men, 4 women) were studied. Paired measurements of MBF at rest (n = 21), during adenosine (n = 15) and during dipyridamole (n = 7) were performed using a two-compartment model for 13N-ammonia PET. The mean difference between baseline and follow-up blood flow (% difference) was calculated to assess reproducibility.

RESULTS

No significant difference was observed between resting blood flow at baseline or follow-up (15.8% +/- 15.8%; p = ns). Baseline and follow-up resting blood flow were linearly correlated (r = 0.63, p < 0.005). Normalization of resting blood flow to the rate pressure product improved the reproducibility significantly (15.8% +/- 15.8% versus 10.1% +/- 10.5%, p < 0.05). Baseline and follow-up hyperemic myocardial blood flow did not differ (11.8% +/- 9.4%; p = ns) and were linearly correlated (r = 0.69, p < 0.0005).

CONCLUSION

MBF at rest can be measured reproducibly with 13N-ammonia PET. The individual response to pharmacologic stress appears to be relatively consistent. Thus, serial blood flow measurements with 13N-ammonia PET can be used to quantify the effect of various interventions on MBF and vasodilatory reserve.

Two human cases of Thelazia callipaeda infection in Korea

Thelazia callipaeda were observed from a 7-month old baby who lived in Uijongbu in 1989 and from a 42-year old man who lived in Anyang in 1994. These are the 23rd and 24th records of human thelaziasis in Korea as the literature are concerned.

Correlation of computed finite element stresses to bone density after remodeling around cementless femoral implants

Fundamental to the development of a durable, uncemented femoral component is an understanding of the remodeling process that goes on after implantation. Predicting the bone remodeling that results from the use of a given hip implant would facilitate the design of a prosthesis that would optimize bone adaptation. This report combines the results of finite element stress analysis of the AML prosthesis implanted in vitro into a proximal femur with quantitative bone mineral density measured in vivo in the medial and lateral aspects of human femora at periods after implantation. Unimplanted femora were also analyzed for comparison purposes. Bone density measurements were obtained using dual energy x-ray absorptiometry. Absolute values of the maximum principal stress and maximum shear stress calculated in the femur at the time of implantation accurately predict bone density resulting from remodeling caused by the prosthesis. The calculated initial strain was not found to correlate with resultant bone density. These findings suggest that the results of stress analyses using three dimensional models of femora implanted in vitro can predict bone remodeling around prostheses and may be used to quantitate appropriate design criteria for total hip replacements.

Femoral prosthesis implantation induces changes in bone stress that depend on the extent of porous coating

The objective of this study was to evaluate the effect of implantation of porous-coated anatomic medullary fitting prostheses on stress in the proximal femur. Three-dimensional finite element models of a cadaveric femur before and after implantation were used to evaluate the resulting changes in stress in the bone. Models of the femur were generated automatically from computed tomographic scan data with use of an innovative mesh-generation technique. The models were analyzed for three levels of porous coating (proximal, 5/8, and full), with the assumption of ideal ingrowth (perfect bonding) over porous areas and a frictionless, tension-free surface on smooth areas. All models were loaded and restrained to represent conditions of normal gait. The stresses predicted in the implanted femur are consistent with clinical observations of proximal cortical atrophy (normal stress reduced to 6-9% of normal at the calcar and 50-55% at mid-prosthesis) and of hypertrophy at the porous coating junctions (normal stress at the 5/8-coating junction, 123% of stress proximal to the junction) and hypertrophy near the distal tip of the prosthesis (anterior and posterior normal stresses 200-800% of normal). The fully coated prosthesis induced stresses in the bone near the tip of the prosthesis that were most like stresses in the normal femur (medial and lateral normal stress 105 and 102% of the stress in the normal femur). Below the collar, the normal stress associated with the proximally coated prosthesis was 6% greater than that produced with the other two levels of coating but still was only 2% of normal. The 5/8-coated prosthesis appeared to combine the worst features of the fully coated and proximally coated prostheses--greater stress-shielding at the calcar and higher stress near the tip of the prosthesis.

Are contraction and relaxation coupled in patients with and without congestive heart failure?

BACKGROUND

Although changes in contractility are often accompanied by changes in relaxation, a mathematical model of ventricular coupling has not been described. A model we examined suggests a hyperbolic relation between measurements of contraction and relaxation. We thus tested the hypothesis that relatively load-independent measurements of contractility (end-systolic elastance [Ees]) and relaxation (the slope of the tau-to-end-systolic pressure relation [R]) were coupled.

METHODS AND RESULTS

To establish the validity of the model, an assessment of Ees and R was made in 30 subjects who underwent sequential digital ventriculography and micromanometer pressure measurements during atrial pacing (93 +/- 10 min-1) before and after graded doses of nitroprusside. To establish if a cyclic AMP (cAMP)-mediated intervention alters coupling, seven of the 30 subjects were studied before and after 3 months of beta-blockade. To determine if a non-cAMP-mediated intervention alters coupling, 12 other patients were studied before and after deslanoside. Nonlinear regression analysis for the initial 30 patients suggested a hyperbolic relation: (Ees) (R) = 1.05 (r = 0.79, p less than 0.001) with an inflection point near Ees = 1.02 mm Hg/ml. Thus, with normal or near-normal contractility, relaxation is normal and not load dependent (R is close to 0). With systolic dysfunction, relaxation becomes very afterload dependent and so must be normalized for load. After long-term beta-blockade in patients with severe left ventricular dysfunction, small improvements in contractility (elastance) occurred with larger changes in relaxation, but the curve describing the relation was not displaced. Acute administration of deslanoside resulted in a large increase in elastance and a smaller change in relaxation but did not alter coupling. However, the magnitude of the change in R was dependent on the predrug R value.

CONCLUSIONS

These data suggest contraction and relaxation may be physiologically coupled with relaxation relatively preserved in early heart failure and more rapid deterioration in relaxation as elastance falls under 1.02 mm Hg/ml. Both beta-blockers (which may act through cAMP) and digitalis (which is cAMP independent) improve contraction and relaxation, but both mechanisms appear to maintain coupling. The hyperbolic relation between contraction and relaxation may have important implications regarding therapeutic response and selection of patients for clinical trials in heart failure.

Alleviation of cocaine-induced coronary vasoconstriction by nitroglycerin

Cocaine induces vasoconstriction of epicardial coronary arteries in patients with and without coronary artery disease, and this vasoconstriction is particularly marked in segments narrowed by atherosclerosis. To assess the effect of nitroglycerin on cocaine-induced coronary vasoconstriction, computer-assisted quantitative analysis was performed on non-diseased and diseased coronary artery segments in 23 patients (18 men, 5 women, aged 43 to 65 years) 1) at baseline, 2) after administration of intranasal saline solution (in 8 patients) or 2 mg/kg of cocaine (in 15 patients), and then 3) after administration of sublingual placebo (in 6 patients) or 0.4 or 0.8 mg of nitroglycerin (in 9 patients) in the 15 patients given cocaine. In response to cocaine administration, coronary artery cross-sectional area decreased 22 +/- 7% (mean +/- SD) in non-diseased segments (p less than 0.05) and 45 +/- 18% in diseased segments (p less than 0.02). The magnitude of vasoconstriction was greater (p = 0.01) in the diseased segments. Sublingual nitroglycerin abolished the vasoconstriction in both non-diseased and diseased segments. Thus, nitroglycerin alleviates cocaine-induced vasoconstriction in patients with coronary artery disease.

Potentiation of cocaine-induced coronary vasoconstriction by beta-adrenergic blockade

STUDY OBJECTIVE

To determine whether beta-adrenergic blockade augments cocaine-induced coronary artery vasoconstriction.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

A cardiac catheterization laboratory in an urban teaching hospital.

PATIENTS

Thirty clinically stable patient volunteers referred for catheterization for evaluation of chest pain.

INTERVENTIONS

Heart rate, arterial pressure, coronary sinus blood flow (by thermodilution), and epicardial left coronary arterial dimensions were measured before and 15 minutes after intranasal saline or cocaine administration (2 mg/kg body weight) and again after intracoronary propranolol administration (2 mg in 5 minutes).

MEASUREMENTS AND MAIN RESULTS

No variables changed after saline administration. After cocaine administration, arterial pressure and rate-pressure product increased; coronary sinus blood flow fell (139 +/- 28 [mean +/- SE] to 120 +/- 20 mL/min); coronary vascular resistance (mean arterial pressure divided by coronary sinus blood flow) rose (0.87 +/- 0.10 to 1.05 +/- 0.10 mm Hg/mL.min); and coronary arterial diameters decreased by between 6% and 9% (P less than 0.05 for all variables). Subsequently, intracoronary propranolol administration caused no change in arterial pressure or rate-pressure product but further decreased coronary sinus blood flow (to 100 +/- 14 mL/min) and increased coronary vascular resistance (to 1.20 +/- 0.12 mm Hg/mL.min) (P less than 0.05 for both).

CONCLUSIONS

Cocaine-induced coronary vasoconstriction is potentiated by beta-adrenergic blockade. Beta-adrenergic blocking agents probably should be avoided in patients with cocaine-associated myocardial ischemia or infarction.

Cocaine-induced coronary-artery vasoconstriction

Intranasal cocaine is used frequently as a local anesthetic during many rhinolaryngologic procedures. Although its "recreational" use in high doses has been associated with chest pain and myocardial infarction, this association has not been established when cocaine is used in low doses as a topical anesthetic, and its effect on the coronary vasculature of humans is unknown. We studied the effects of intranasal cocaine (10 percent cocaine hydrochloride; 2 mg per kilogram of body weight) on the blood flow in and dimensions of the coronary arteries and on myocardial oxygen demand in 45 patients (34 men and 11 women, 36 to 67 years of age) who were undergoing cardiac catheterization for the evaluation of chest pain. Heart rate, arterial pressure, blood flow in the coronary sinus (measured by thermodilution), and the dimensions of the epicardial left coronary artery (measured by quantitative arteriography) were measured before and 15 minutes after the intranasal administration of saline (in 16 patients) or cocaine (in 29). No variables changed after the administration of saline. After cocaine was administered, the heart rate and arterial pressure rose, the coronary-sinus blood flow fell (from a mean [+/- SD] of 149 +/- 59 ml per minute to 124 +/- 53 ml per minute), and the diameter of the left coronary artery decreased by 8 to 12 percent (P less than 0.01 for all comparisons). No patient had chest pain or electrocardiographic evidence of myocardial ischemia after the administration of cocaine. Subsequently, the administration of the alpha-adrenergic blocking agent phentolamine caused all these values to return to base-line levels. There was no difference in response between the patients found to have disease of the left coronary artery (n = 28) and those without such disease (n = 17). We conclude that the intranasal administration of cocaine near the dose used for topical anesthesia causes vasoconstriction of the coronary arteries, with a decrease in the coronary blood flow, despite an increase in myocardial oxygen demand, and that these effects are mediated by alpha-adrenergic stimulation. It is reasonable to assume that these effects would be more pronounced at the much higher doses associated with the recreational use of cocaine.