P3432Coronary artery calcium score is of limited sensitivity in detecting subclinical atherosclerosis in young individuals with family history of coronary artery disease

Introduction

Family history of premature coronary artery disease (CAD) is known to predispose individuals to adverse CAD events, often at a younger age. Current risk stratification strategy is suboptimal, as up to 50% of individuals were considered “low-risk” prior to their first presentation of myocardial infarction. Coronary artery calcium score (CACS) is a marker of atherosclerosis and provides incremental value in risk stratification. However, the utility of CACS may be limited in younger patients as they often have non-calcified atherosclerotic plaques. In this study, we evaluate the sensitivity of CACS in detecting subclinical atherosclerosis in different age groups.

Method

From 310 referrals to a specialized unit in the management of early atherosclerosis, 222 individuals with a family history of premature CAD (defined as CAD events in first-degree family members, male<55 and female<65) and aged between 35 and 55 were enrolled for assessment of their CAD risks. Individuals with possible, probably or definite familial hypercholesterolemia were excluded. In addition to clinical and risk factor evaluation, cardiac CT and CACS were performed in select individuals, at the discretion of the treating physician.

Results

Of the 141 (59% male, mean age 45.9±6.0 year) individuals that completed clinical evaluation, 65 (73% male, mean age 47.4±6.9 years) have subclinical atherosclerosis (defined by the presence of atherosclerotic plaques in any of the coronary artery segments in cardiac CT). Of them, 52 have CACS>0, giving an overall sensitivity of 80%. The breakdown by age group is shown in table 1. The sensitivity of CACS in detecting subclinical atherosclerosis is quite modest in younger individuals (60% in individuals <45 year-old) but improves with patient age (>85% in >45 years).

Table 1. Sensitivity of CACS in different age groups Age group True Positive Fast Negative Sensitivity N (CAC+ CTCA+) (CAC+ CTCA−) (%) <40 6 4 60 10 41–45 7 4 55 11 46–50 19 3 86 22 51–55 20 1 95 21

Conclusion

In younger individuals (<45 years) with family history of premature CAD, CACS is of limited sensitivity in detecting subclinical atherosclerosis, and should not be used to rule out CAD. Further studies are warranted.

Reduced Translocation of Glyphosate and Dicamba in Combination Contributes to Poor Control of Kochia scoparia: Evidence of Herbicide Antagonism

Kochia scoparia is a troublesome weed across the Great Plains of North America. Glyphosate and dicamba have been used for decades to control K. scoparia. Due to extensive selection, glyphosate- and dicamba-resistant (GDR) K. scoparia have evolved in the USA. Herbicide mixtures are routinely used to improve weed control. Herbicide interactions if result in an antagonistic effect can significantly affect the management of weeds, such as K. scoparia. To uncover the interaction of glyphosate and dicamba when applied in combination in K. scoparia management the efficacies of different doses of glyphosate plus dicamba were evaluated under greenhouse and field conditions using GDR and a known glyphosate- and dicamba-susceptible (GDS) K. scoparia. The results of greenhouse and field studies suggest that the combination of glyphosate and dicamba application controlled GDS, but glyphosate alone provided a better control of GDR K. scoparia compared to glyphosate plus dicamba combinations. Furthermore, investigation of the basis of this response suggested glyphosate and dicamba interact antagonistically and consequently, the translocation of both herbicides was significantly reduced resulting in poor control of K. scoparia. Therefore, a combination of glyphosate plus dicamba may not be a viable option to control GDR K. scoparia.

Rapid detoxification via glutathione S-transferase (GST) conjugation confers a high level of atrazine resistance in Palmer amaranth (Amaranthus palmeri)

BACKGROUND

Palmer amaranth (Amaranthus palmeri) is an economically troublesome, aggressive and damaging weed that has evolved resistance to six herbicide modes of action including photosystem II (PS II) inhibitors such as atrazine. The objective of this study was to investigate the mechanism and inheritance of atrazine resistance in Palmer amaranth.

RESULTS

A population of Palmer amaranth from Kansas (KSR) had a high level (160 - 198-fold more; SE ±21 - 26) of resistance to atrazine compared to the two known susceptible populations MSS and KSS, from Mississippi and Kansas, respectively. Sequence analysis of the chloroplastic psbA gene did not reveal any known mutations conferring resistance to PS II inhibitors, including the most common Ser264Gly substitution for triazine resistance. However, the KSR plants rapidly conjugated atrazine at least 24 times faster than MSS via glutathione S-transferase (GST) activity. Furthermore, genetic analyses of progeny generated from reciprocal crosses of KSR and MSS demonstrate that atrazine resistance in Palmer amaranth is a nuclear trait.

CONCLUSION

Although triazine resistance in Palmer amaranth was reported more than 20 years ago in the USA, this is the first report elucidating the underlying mechanism of resistance to atrazine. The non-target-site based metabolic resistance to atrazine mediated by GST activity may predispose the Palmer amaranth populations to have resistance to other herbicide families, and the nuclear inheritance of the trait in this dioecious species further exacerbates the propensity for its rapid spread. © 2017 Society of Chemical Industry.

Physiological and Molecular Characterization of Hydroxyphenylpyruvate Dioxygenase (HPPD)-inhibitor Resistance in Palmer Amaranth (Amaranthus palmeri S.Wats.)

Herbicides that inhibit hydroxyphenylpyruvate dioxygenase (HPPD) such as mesotrione are widely used to control a broad spectrum of weeds in agriculture. Amaranthus palmeri is an economically troublesome weed throughout the United States. The first case of evolution of resistance to HPPD-inhibiting herbicides in A. palmeri was documented in Kansas (KS) and later in Nebraska (NE). The objective of this study was to investigate the mechansim of HPPD-inhibitor (mesotrione) resistance in A. palmeri. Dose response analysis revealed that this population (KSR) was 10-18 times more resistant than their sensitive counterparts (MSS or KSS). Absorbtion and translocation analysis of [¹⁴C] mesotrione suggested that these mechanisms were not involved in the resistance in A. palmeri. Importantly, mesotrione (>90%) was detoxified markedly faster in the resistant populations (KSR and NER), within 24 hours after treatment (HAT) compared to sensitive plants (MSS, KSS, or NER). However, at 48 HAT all populations metabolized the mesotrione, suggesting additional factors may contribute to this resistance. Further evaluation of mesotrione-resistant A. palmeri did not reveal any specific resistance-conferring mutations nor amplification of HPPD gene, the molecular target of mesotrione. However, the resistant populations showed 4- to 12-fold increase in HPPD gene expression. This increase in HPPD transcript levels was accompanied by increased HPPD protein expression. The significant aspects of this research include: the mesotrione resistance in A. palmeri is conferred primarily by rapid detoxification (non-target-site based) of mesotrione; additionally, increased HPPD gene expression (target-site based) also contributes to the resistance mechanism in the evolution of herbicide resistance in this naturally occurring weed species.

Micropost arrays for measuring stem cell-derived cardiomyocyte contractility

Stem cell-derived cardiomyocytes have the potential to be used to study heart disease and maturation, screen drug treatments, and restore heart function. Here, we discuss the procedures involved in using micropost arrays to measure the contractile forces generated by stem cell-derived cardiomyocytes. Cardiomyocyte contractility is needed for the heart to pump blood, so measuring the contractile forces of cardiomyocytes is a straightforward way to assess their function. Microfabrication and soft lithography techniques are utilized to create identical arrays of flexible, silicone microposts from a common master. Micropost arrays are functionalized with extracellular matrix protein to allow cardiomyocytes to adhere to the tips of the microposts. Live imaging is used to capture videos of the deflection of microposts caused by the contraction of the cardiomyocytes. Image analysis code provides an accurate means to quantify these deflections. The contractile forces produced by a beating cardiomyocyte are calculated by modeling the microposts as cantilever beams. We have used this assay to assess techniques for improving the maturation and contractile function of stem cell-derived cardiomyocytes.

Field-evolved resistance to four modes of action of herbicides in a single kochia (Kochia scoparia L. Schrad.) population

BACKGROUND

Evolution of multiple herbicide resistance in weeds is a serious threat to weed management in crop production. Kochia is an economically important broadleaf weed in the U.S. Great Plains. This study aimed to confirm resistance to four sites of action of herbicides in a single kochia (Kochia scoparia L. Schrad.) population from a crop field near Garden City (GC), Kansas, and further determine the underlying mechanisms of resistance.

RESULTS

One-fourth of the GC plants survived the labeled rate or higher of atrazine [photosystem II (PSII) inhibitor], and the surviving plants had the Ser-264 to Gly mutation in the psbA gene, the target site of atrazine. Results showed that 90% of GC plants survived the labeled rate of dicamba, a synthetic auxin. At least 87% of the plants survived up to 72 g a.i. ha(-1) of chlorsulfuron [acetolactate synthase (ALS) inhibitor], and analysis of the ALS gene revealed the presence of Pro-197 to Thr and/or Trp-574 to Lue mutation(s). Most GC plants also survived the labeled rate of glyphosate [5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor), and the resistant plants had 5-9 EPSPS gene copies (relative to the ALS gene).

CONCLUSION

We confirm the first case of evolution of resistance to four herbicide sites of action (PSII, ALS and EPSPS inhibitors and synthetic auxins) in a single kochia population, and target-site-based mechanisms confer resistance to atrazine, glyphosate and chlorsulfuron.

Physiological and Molecular Mechanisms of Differential Sensitivity of Palmer Amaranth (Amaranthus palmeri) to Mesotrione at Varying Growth Temperatures

Herbicide efficacy is known to be influenced by temperature, however, underlying mechanism(s) are poorly understood. A marked alteration in mesotrione [a 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor] efficacy on Palmer amaranth (Amaranthus palmeri S. Watson) was observed when grown under low- (LT, 25/15 °C, day/night temperatures) and high (HT, 40/30° C) temperature compared to optimum (OT, 32.5/22.5 °C) temperature. Based on plant height, injury, and mortality, Palmer amaranth was more sensitive to mesotrione at LT and less sensitive at HT compared to OT (ED50 for mortality; 18.5, 52.3, and 63.7 g ai ha-1, respectively). Similar responses were observed for leaf chlorophyll index and photochemical efficiency of PSII (Fv/Fm). Furthermore, mesotrione translocation and metabolism, and HPPD expression data strongly supported such variation. Relatively more mesotrione was translocated to meristematic regions at LT or OT than at HT. Based on T50 values (time required to metabolize 50% of the 14C mesotrione), plants at HT metabolized mesotrione faster than those at LT or OT (T50; 13, 21, and 16.5 h, respectively). The relative HPPD:CPS (carbamoyl phosphate synthetase) or HPPD:β-tubulin expression in mesotrione-treated plants increased over time in all temperature regimes; however, at 48 HAT, the HPPD:β-tubulin expression was exceedingly higher at HT compared to LT or OT (18.4-, 3.1-, and 3.5-fold relative to untreated plants, respectively). These findings together with an integrated understanding of other interacting key environmental factors will have important implications for a predictable approach for effective weed management.

Highly elevated atmospheric levels of volatile organic compounds in the Uintah Basin, Utah

Oil and natural gas production in the Western United States has grown rapidly in recent years, and with this industrial expansion, growing environmental concerns have arisen regarding impacts on water supplies and air quality. Recent studies have revealed highly enhanced atmospheric levels of volatile organic compounds (VOCs) from primary emissions in regions of heavy oil and gas development and associated rapid photochemical production of ozone during winter. Here, we present surface and vertical profile observations of VOC from the Uintah Basin Winter Ozone Studies conducted in January-February of 2012 and 2013. These measurements identify highly elevated levels of atmospheric alkane hydrocarbons with enhanced rates of C2-C5 nonmethane hydrocarbon (NMHC) mean mole fractions during temperature inversion events in 2013 at 200-300 times above the regional and seasonal background. Elevated atmospheric NMHC mole fractions coincided with build-up of ambient 1-h ozone to levels exceeding 150 ppbv (parts per billion by volume). The total annual mass flux of C2-C7 VOC was estimated at 194 ± 56 × 10(6) kg yr(-1), equivalent to the annual VOC emissions of a fleet of ∼100 million automobiles. Total annual fugitive emission of the aromatic compounds benzene and toluene, considered air toxics, were estimated at 1.6 ± 0.4 × 10(6) and 2.0 ± 0.5 × 10(6) kg yr(-1), respectively. These observations reveal a strong causal link between oil and gas emissions, accumulation of air toxics, and significant production of ozone in the atmospheric surface layer.

Transcatheter aortic valve implantation: durability of clinical and hemodynamic outcomes beyond 3 years in a large patient cohort

BACKGROUND

Although short- and medium-term outcomes after transcatheter aortic valve implantation are encouraging, long-term data on valve function and clinical outcomes are limited.

METHODS AND RESULTS

Consecutive high-risk patients who had been declined as surgical candidates because of comorbidities but who underwent successful transcatheter aortic valve implantation with a balloon-expandable valve between January 2005 and December 2006 and survived past 30 days were assessed. Clinical, echocardiographic, and computed tomographic follow-up examinations were performed. Seventy patients who underwent successful procedures and survived longer than 30 days were evaluated at a minimum follow-up of 3 years. At a median follow-up of 3.7 years (interquartile range 3.4 to 4.3 years), survival was 57%. Survival at 1, 2, and 3 years was 81%, 74%, and 61%, respectively. Freedom from reoperation was 98.5% (1 patient with endocarditis). During this early procedural experience, 11 patients died within 30 days, and 8 procedures were unsuccessful. When these patients were included, overall survival was 51%. Transaortic pressure gradients increased from 10.0 mm Hg (interquartile range 8.0 to 12.0 mm Hg) immediately after the procedure to 12.1 mm Hg (interquartile range 8.6 to 16.0 mm Hg) after 3 years (P=0.03). Bioprosthetic valve area decreased from a mean of 1.7±0.4 cm(2) after the procedure to 1.4±0.3 cm(2) after 3 years (P<0.01). Aortic incompetence after implantation was trivial or mild in 84% of cases and remained unchanged or improved over time. There were no cases of structural valvular deterioration, stent fracture, deformation, or valve migration.

CONCLUSIONS

Transcatheter aortic valve implantation demonstrates good medium- to long-term durability and preserved hemodynamic function, with no evidence of structural failure. The procedure appears to offer an adequate and lasting resolution of aortic stenosis in selected patients.

Deceleration time of systolic pulmonary venous flow: a new clinical marker of left atrial pressure and compliance

The curvilinearity of the atrial pressure-volume curve implies that atrial compliance decreases progressively with increasing left atrial (LA) pressure (LAP). We predicted that reduced LA compliance leads to more rapid deceleration of systolic pulmonary venous (PV) flow. With this rationale, we investigated whether the deceleration time ( tdec) of PV systolic flow velocity reflects mean LAP. In eight patients during coronary surgery, before extracorporeal circulation, PV flow by ultrasonic transit time and invasive LAP were recorded during stepwise volume loading. The tdec was calculated using two methods: by drawing a tangent through peak deceleration and by drawing a line from peak systolic flow through the nadir between the systolic and early diastolic flow waves. LA compliance was calculated as the systolic PV flow integral divided by LAP increment. Volume loading increased mean LAP from 11 ± 3 to 20 ± 5 mmHg ( P < 0.001) ( n = 40), reduced LA compliance from 1.16 ± 0.42 to 0.72 ± 0.40 ml/mmHg ( P < 0.004) ( n = 40), and reduced tdec from 320 ± 50 to 170 ± 40 ms ( P < 0.0005) ( n = 40). Mean LAP correlated well with tdec ( r = 0.84, P < 0.0005) ( n = 40) and LA compliance ( r = 0.79, P < 0.0005) ( n = 40). Elevated LAP caused a decrease in LA compliance and therefore more rapid deceleration of systolic PV flow. The tdec has potential to become a semiquantitative marker of LAP and an index of LA passive elastic properties.

Cross-induction of cell types in Dictyostelium: evidence that DIF-1 is made by prespore cells

To investigate how cell type proportions are regulated during Dictyostelium development, we have attempted to find out which cell type produces DIF-1, a diffusible signal molecule inducing the differentiation of prestalk-O cells. DIF-1 is a chlorinated alkyl phenone that is synthesized from a C12 polyketide precursor by chlorination and methylation, with the final step catalysed by the dmtA methyltransferase. All our evidence points to the prespore cells as the major source of DIF-1. (1) dmtA mRNA and enzyme activity are greatly enriched in prespore compared with prestalk cells. The chlorinating activity is also somewhat prespore-enriched. (2) Expression of dmtA is induced by cyclic-AMP and this induction is inhibited by DIF-1. This regulatory behaviour is characteristic of prespore products. (3) Short-term labelling experiments, using the polyketide precursor, show that purified prespore cells produce DIF-1 at more than 20 times the rate of prestalk cells. (4) Although DIF-1 has little effect on its own synthesis in short-term labelling experiments, in long-term experiments, using 36Cl– as label, it is strongly inhibitory (IC50 about 5 nM), presumably because it represses expression of dmtA; this is again consistent with DIF-1 production by prespore cells. Inhibition takes about 1 hour to become effective.

We propose that prespore cells cross-induce the differentiation of prestalk-O cells by making DIF-1, and that this is one of the regulatory loops that sets the proportion of prespore-to-prestalk cells in the aggregate.

The deceleration [correction of declaration] time of pulmonary venous diastolic flow is more accurate than the pulmonary artery occlusion pressure in predicting left atrial pressure

OBJECTIVES

This study compared a prediction of mean left atrial pressure (P(LA)) ascertained by Doppler echocardiography of pulmonary venous flow (PVF), with predicted P(LA) using the pulmonary artery occlusion pressure (P(PAO)).

BACKGROUND

In select patient groups, PVF variables correlate with P(PAO)) an indirect measure of P(LA).

METHODS

In 93 patients undergoing cardiac surgery, we recorded with transesophageal echocardiography mitral valve early (E) and late (A) wave velocities, deceleration time (DT) of E (DT(E)), and pulmonary vein systolic (S) and diastolic (D) wave velocities, DT of D (DT(D)) and systolic fraction. The P(PAO) was measured using a pulmonary artery catheter zeroed to midaxillary level. A further catheter was held at midatrial level to zero a transducer and was then inserted into the left atrium. A prediction rule for P(LA) from DT(D) was developed in 50 patients and applied prospectively to estimate P(LA) in 43 patients.

RESULTS

A close correlation (r = -0.92) was found between P(LA) and DT(D). Systolic fraction (r = -0.63), DT(E) (r = -0.61), D wave (r = 0.57), E wave (r = 0.52), and E/A ratio (r = 0.13) correlated less closely with P(LA). The mean difference between predicted and measured P(LA) was 0.58 mm Hg for DT(D) method and 1.72 mm Hg for P(PAO), with limits of agreement (mean +/- 2 SE) of -2.94 to 4.10 mm Hg and -2.48 to 5.92 mm Hg, respectively. A DT(D)) of <175 ms had 100% sensitivity and 94% specificity for a P(LA) of >17 mm Hg.

CONCLUSIONS

Deceleration time of pulmonary vein diastolic wave is more accurate than P(PAO) in estimating left atrial pressure in cardiac surgical patients.

Monocular elevator paresis in neurofibromatosis type 2

A retrospective review of 29 consecutive unselected patients referred for neuro-ophthalmic evaluation after the diagnosis of neurofibromatosis type 2 (NF2) showed that four of them had a monocular elevator paresis. In two of the four MRI demonstrated lesions, presumed to be schwannomas, of the third nerve. These findings indicate that monocular elevator paresis is a common neuro-ophthalmic finding in NF2, which the authors suspect is probably a sign of third nerve infiltration or compression by a schwannoma.

Conflict of interest: organizational vs. executive ethics in health care

This survey of 207 senior- and mid-level administrators from across the U.S. details the surprising level and type of ethical conflicts and unethical practices they face on the job and how their organizations create and respond to these challenges. The findings suggest widespread ethical conflict caused by situational and environmental factors, financial incentives, boards of directors, and stakeholder pressure. Particularly poignant is the apparent inability of executives to alter the ethical environment. Substantial differences were found between nonprofit and proprietary sector administrators as well as gender and age groups.

Thermostability and thermoactivity of citrate synthases from the thermophilic and hyperthermophilic archaea, Thermoplasma acidophilum and Pyrococcus furiosus

Citrate synthases from Thermoplasma acidophilum (optimal growth at 55 degrees C) and Pyrococcus furiosus (100 degrees C) are homo-dimeric enzymes that show a high degree of structural homology with each other, and thermostabilities commensurate with the environmental temperatures in which their host cells are found. A comparison of their atomic structures with citrate synthases from mesophilic and psychrophilic organisms has indicated the potential importance of inter-subunit contacts for thermostability, and here we report the construction and analysis of site-directed mutants of the two citrate synthases to investigate the contribution of these interactions. Three sets of mutants were made: (a) chimeric mutants where the large (inter-subunit contact) and small (catalytic) domains of the T. acidophilum and P. furiosus enzymes were swapped; (b) mutants of the P. furiosus citrate synthase where the inter-subunit ionic network is disrupted; and (c) P. furiosus citrate synthase mutants in which the C-terminal arms that wrap around their partner subunits have been deleted. All three sets of mutant enzymes were expressed as recombinant proteins in Escherichia coli and were found to be catalytically active. Kinetic parameters and the dependence of catalytic activity on temperature were determined, and the stability of each enzyme was analysed by irreversible thermal inactivation experiments. The chimeric mutants indicate that the thermostability of the whole enzyme is largely determined by the origin of the large, inter-subunit domain, whereas the dependence of catalytic activity on temperature is a function of the small domain. Disruption of the inter-subunit ionic network and prevention of the C-terminal interactions both generated enzymes that were substantially less thermostable. Taken together, these data demonstrate the crucial importance of the subunit contacts to the stability of these oligomeric enzymes. Additionally, they also provide a clear distinction between thermostability and thermoactivity, showing that stability is necessary for, but does not guarantee, catalytic activity at elevated temperatures.

Atrioventricular filling dynamics, diastolic function and dysfunction

Left ventricular diastolic dysfunction is associated with slowing of LV relaxation and a decrease in LV chamber compliance. This impairment of function leads to changes in filling velocities as measured by pulsed wave Doppler echocardiography in the pulmonary veins and across the mitral valve, and in intraventricular flow propagation velocity as measured by color M-mode Doppler. This paper explores some of the physiology of LV filling in a clinical context.

The role of DIF-1 signaling in Dictyostelium development

We have constructed a mutant blocked in the biosynthesis of DIF-1, a chlorinated signal molecule proposed to induce differentiation of both major prestalk cell types formed during Dictyostelium development. Surprisingly, the mutant still forms slugs retaining one prestalk cell type, the pstA cells, and can form mature stalk cells. However, the other major prestalk cell type, the pstO cells, is missing. Normal pstO cell differentiation and their patterning in the slug are restored by development on a uniform concentration of DIF-1. We conclude that pstO and pstA cells are in fact induced by separate signals and that DIF-1 is the pstO inducer. Positional information, in the form of DIF-1 gradients, is evidently not required for pstO cell induction.

Cell-fate choice in Dictyostelium: intrinsic biases modulate sensitivity to DIF signaling

Cell fate in Dictyostelium development depends on intrinsic differences between cells, dating from their growth period, and on cell interactions occurring during development. We have sought for a mechanism linking these two influences on cell fate. First, we confirmed earlier work showing that the vegetative differences are biases, not commitments, since cells that are stalky-biased when developed with one partner are sporey with another. Then we tested the idea that these biases operate by modulating the sensitivity of cells to the signals controlling cell fate during development. Cells grown without glucose are stalky-biased when developed with cells grown with glucose. We find, using monolayer culture conditions, that they are more sensitive to each of the stalk-inducing signals, DIFs 1-3. Mixing experiments show that this bias is a cell-intrinsic property. Cells initiating development early in the cell cycle are stalky compared to those initiating development later in the cycle. Likewise, they are more sensitive to DIF-1. Assays of standard markers for prestalk and prespore cell differentiation reveal similar differences in DIF-1 sensitivity between biased cells; DIF-1 dechlorinase (an early prestalk cell marker enzyme) behaves in a consistent manner. We propose that cell-fate biases are manifest as differences in sensitivity to DIF.

Cardiogenic shock due to acute severe mitral regurgitation complicating acute myocardial infarction: a report from the SHOCK Trial Registry. SHould we use emergently revascularize Occluded Coronaries in cardiogenic shocK?

OBJECTIVES

Our objective was to define the outcomes of patients with cardiogenic shock (CS) due to severe mitral regurgitation (MR) complicating acute myocardial infarction (AMI).

BACKGROUND

Methods for early identification and optimal treatment of such patients have not been defined.

METHODS

The SHOCK Trial Registry enrolled 1,190 patients with CS complicating AMI. We compared 1) the cohort with severe mitral regurgitation (MR, n = 98) to the cohort with predominant left ventricular failure (LVF, n = 879), and 2) the MR patients who underwent valve surgery (n = 43) to those who did not (n = 51).

RESULTS

Shock developed early after MI in both the MR (median 12.8 h) and LVF (median 6.2 h) cohorts. The MR patients were more often female (52% vs. 37%, p = 0.004) and less likely to have ST elevation at shock diagnosis (41% vs. 63%, p < 0.001). The MR index MI was more frequently inferior (55% vs. 44%, p = 0.039) or posterior (32% vs. 17%, p = 0.002) than that of LVF and much less frequently anterior (34% vs. 59%, p < 0.001). Despite having higher mean LVEF (0.37 vs. 0.30, p = 0.001) the MR cohort had similar in-hospital mortality (55% vs. 61%, p = 0.277). The majority of MR patients did not undergo mitral valve surgery. Those undergoing surgery exhibited higher mean LVEF than those not undergoing surgery; nevertheless, 39% died in hospital.

CONCLUSIONS

The data highlight opportunities for early identification and intervention to potentially decrease the devastating mortality and morbidity of severe post-myocardial infarction MR.

Collaborative angiographic patency trial of recombinant staphylokinase (CAPTORS)

BACKGROUND

We undertook an angiographic, dose-finding study of staphylokinase (SAK42D variant) to evaluate its efficacy and safety in patients with acute ST-segment myocardial infarction.

METHODS AND RESULTS

Patients were studied within 6 hours of symptom onset and received SAK42D as a 30-minute infusion with 20% of the total dose given as a bolus. Eighty-two patients with a median age of 60 years (interquartile range 52 to 69 years), 84% male and 43% with an anterior myocardial infarction, were studied at a median time from symptom onset of 2.7 hours. There was a high degree of Thrombolysis in Myocardial Infarction (TIMI) 3 flow achieved with 15 mg of SAK42D, that is, 62%. Therefore after 21 patients had been studied at this dose the next dose of 30 mg was used and 65% TIMI 3 patency was achieved. At the peak dose of 45 mg, TIMI 3 90-minute patency was 63%. There were no allergic reactions, and no patient had intracranial hemorrhage. Four patients had major and 9 moderate bleeding during the study; 2 of the major and 5 of the moderate bleeding events occurred within 48 hours of commencement of treatment. The majority (62%) of these were related to vascular instrumentation, and there was no relation between the extent of bleeding and dose of SAK42D used. Forty-five minutes after cessation of SAK42D, there were small percent decrements in plasma fibrinogen and plasminogen levels that did not reach statistical significance. However, there were dose-related changes in alpha(2) anti-plasmin that revealed a borderline significant reduction that was dose related (P =.053).

CONCLUSION

These data revealed similar fibrinolytic efficacy across a 3-fold increment in dose, indicating that this study operated on a flat portion of the dose-response curve. The favorable efficacy/safety profile achieved with staphylokinase is encouraging, and further investigation is warranted.

Left ventricular morphology in junior and master resistance trained athletes

PURPOSE

The objective of this cross-sectional investigation was to assess the effects of short (< 5 yr) versus long-term (> or = 18 yr) resistance training (RT) on left ventricular (LV) dimensions and mass.

METHODS

The subjects for this study were 20 elite male powerlifters (8 junior athletes [JA], mean +/- SD, age: 21.1 +/- 1.2 yr and 12 master athletes [MA], age: 46.0 +/- 5.5 yr) and 19 age-matched male controls (8 young controls [YC], age: 21.8 +/- 2.8 yr and 11 middle-aged controls [MAC], age: 46.8 +/- 4.4 yr). Two-dimensionally guided transthoracic M-mode echocardiograms were performed at rest to quantify LV systolic and diastolic cavity dimension (LVIDs and LVIDd, respectively), ventricular septal wall thickness (VST), posterior wall thickness (PWT), LV mass (LVM), and LV systolic function as measured as fractional shortening (FS).

RESULTS

Short- or long-term RT was not associated with a significant alteration in LVIDd (JA: 53.2 +/- 4.5 mm, YC: 52.1 +/- 3.7 mm, MA: 53.0 +/- 5.1 mm, MAC: 51.8 +/- 4.4 mm), LVIDs (JA: 33.5 +/- 4.8 mm, YC: 32.9 +/- 3.4 mm, MA: 33.0 +/- 4.4 mm, MAC: 31.4 +/- 3.7 mm), VST (JA: 9.4 +/- 0.9 mm, YC: 9.4 +/- 0.9 mm, MA: 9.4 +/- 1.6 mm, MAC: 9.7 +/- 0.9 mm), PWT (JA: 9.2 +/- 0.9 mm, YC: 9.4 +/- 0.9 mm, MA: 9.0 +/- 1.1 mm, MAC: 9.5 +/- 1.0 mm), LVM (JA: 184.6 +/- 36.1 g, YC: 179.0 +/- 26.5 g, MA, 183.3 +/- 58.1 g, MAC: 184.1 +/- 38.1 g), or FS (JA: 0.37 +/- 0.1%, YC: 0.37 +/- 0.05%, MA: 0.38 +/- 0.1%, MAC: 0.40 +/- 0.04%).

CONCLUSIONS

These findings suggest that short or long-term RT as performed by elite junior and master powerlifters does not alter LV morphology or systolic function.

Mechanism of pulmonary venous pressure and flow waves

The pulmonary venous systolic flow wave has been attributed both to left heart phenomena, such as left atrial relaxation and descent of the mitral annulus, and to propagation of the pulmonary artery pressure pulse through the pulmonary bed from the right ventricle. In this study we hypothesized that all waves in the pulmonary veins originate in the left heart, and that the gross wave features observed in measurements can be explained simply by wave propagation and reflection. A mathematical model of the pulmonary vein was developed; the pulmonary vein was modeled as a lossless transmission line and the pulmonary bed by a three-element lumped parameter model accounting for viscous losses, compliance, and inertia. We assumed that all pulsations originate in the left atrium (LA), the pressure in the pulmonary bed being constant. The model was validated using pulmonary vein pressure and flow recorded 1 cm proximal to the junction of the vein with the left atrium during aortocoronary bypass surgery. For a pressure drop of 6 mmHg across the pulmonary bed, we found a transit time from the left atrium to the pulmonary bed of tau approximately 150ms, a compliance of the pulmonary bed of C approximately 0.4 ml/mmHg, and an inertance of the pulmonary bed of 1.1 mmHgs2/ml. The pulse wave velocity of the pulmonary vein was estimated to be c approximately 1m/s. Waves, however, travel both towards the left atrium and towards the pulmonary bed. Waves traveling towards the left atrium are attributed to the reflections caused by the mismatch of impedance of line (pulmonary vein) and load (pulmonary bed). Wave intensity analysis was used to identify a period in systole of net wave propagation towards the left atrium for both measurements and model. The linear separation technique was used to split the pressure into one component traveling from the left atrium to the pulmonary bed and a reflected component propagating from the pulmonary bed to the left atrium. The peak of the reflected pressure wave corresponded well with the positive peak in wave intensity in systole. We conclude that the gross features of the pressure and flow waves in the pulmonary vein can be explained in the following manner: the waves originate in the LA and travel towards the pulmonary bed, where reflections give rise to waves traveling back to the LA. Although the gross features of the measured pressure were captured well by the model predicted pressure, there was still some discrepancy between the two. Thus, other factors initiating or influencing waves traveling towards the LA cannot be excluded.

DIF signalling and cell fate

The DIFs are a family of secreted chlorinated molecules that control cell fate during development of Dictyostelium cells in culture and probably during normal development too. They induce stalk cell differentiation and suppress spore cell formation. The biosynthetic and inactivation pathways of DIF-1 (the major bioactivity) have been worked out. DIF-1 is probably synthesised in prespore cells and inactivated in prestalk cells, by dechlorination. Thus, each cell type tends to alter DIF-1 level so as to favour differentiation of the other cell type. This relationship leads to a model for cell-type proportioning during normal development.

An operational model for patient-centered informatics

There are no multidisciplinary operational models to guide nursing informaticists and clinical system users in the design and implementation of computer-supported multidisciplinary care. The Patient-Centered Informatics Model is offered as just such a pragmatic guide. It fuses earlier work with new concepts and allows a visual depiction of crucial elements-influencing factors such as regulations and healthcare delivery models, system attributes such as healthcare delivery methods, knowledge base and supporting technology and categories of results of application processing. The model can help users and executives organize their thinking about the design, implementation, and evaluation of clinical systems in complex settings.

Carvedilol improves functional class in patients with severe left ventricular dysfunction referred for heart transplantation

PURPOSE

Limited options are available to improve the functional class of patients awaiting cardiac transplantation. We assessed the effect of carvedilol on New York Heart Association (NYHA) class, heart rate (HR), blood pressure (BP), jugular venous pressure (JVP), electrolytes and renal function in patients with markedly decreased left ventricular (LV) function referred for cardiac transplantation assessment.

METHODS

Sixty-one patients (age = 52 +/- 12 yr, EF = 23 +/- 7%, VO2 max = 16 +/- 5 mL/kg/min) referred to the cardiac transplant clinic were reviewed before and after the addition of carvedilol (starting dose 3.125 mg twice daily to target dose of 25 mg twice daily) to usual heart-failure therapy. Over a 1-yr period, at each visit prior to initiation, at baseline initiation visit and at each follow-up visit, NYHA class, BP, HR, JVP, electrolytes, and renal function were obtained. Statistical analysis was performed using random effects regression approach. A multiple logistic regression analysis was performed on 52/61 patients to determine possible associations between NYHA improvement and the following patient characteristics: sex, etiology of cardiomyopathy, initial NYHA class, and dose of carvedilol.

RESULTS

Three patients died (2 after stopping carvedilol) and 3 were transplanted. Median follow-up was 100 d. Sixteen patients reached the target dose after a mean of 137 d (2.75 visits). Estimated time-to-target dose is 8 months (5.6 visits). BP tended to increase (p = 0.07 for change in trend) with no change in JVP, electrolytes or renal function. HR decreased 6 +/- 3 b.p.m. (p = 0.03). Of 14 patients NYHA class I/II at baseline, none were class III/IV at last follow-up visit. Of 47 patients NYHA class III/IV at baseline, 25 were class I/II, and 22 were class III/IV at last follow-up (p < 0.001). Multiple logistic regression analysis did not demonstrate any factor predictive of subsequent NYHA class improvement.

CONCLUSIONS

Despite less than target doses in most patients, a favorable effect of carvedilol on functional class in patients with severe congestive heart failure (CHF) referred for transplant was observed. Those with good functional status remained stable and those with poor functional status improved or remained stable. No baseline patient characteristic predicted improvement. The shortage of donor organ requires optimal use of medical regimens which may improve functional class while awaiting transplantation and which may delay the necessity for heart transplantation. Therefore, addition of carvedilol to usual medical therapy may be beneficial even in patients with severe LV dysfunction and poor NYHA classification.

New method for detection of heart allograft rejection: validation of sensitivity and reliability in a rat heterotopic allograft model

BACKGROUND

Patients with inflammatory heart muscle diseases would benefit from a safe, convenient, rapidly performed diagnostic technique with real-time results not involving tissue removal. We have performed a detailed evaluation of detection of heart allograft rejection by autofluorescence in a heterotopic abdominal rat heart allograft model ex vivo.

METHODS AND RESULTS

Recipient rats with allograft (Lewis to Fisher 344; n=71) and isograft (Lewis to Lewis; n=33) hearts, treated with cyclosporine or untreated, were killed at days 2, 4, 7, 14, 21, 28, and 56 after transplant. Nontransplant controls with (n=24) or without (n=24) immunosuppressive therapy were also studied. When the rats were killed, autofluorescence spectra were acquired under blue-light excitation from midtransverse ventricular sections of native and transplanted hearts. Corresponding sections were then evaluated pathologically by a modified International Society for Heart and Lung Transplantation (ISHLT) grading schema. The spectral differences between rejecting and nonrejecting hearts were quantified by linear discriminant functions, producing scores that decreased progressively with increasing severity of tissue rejection. Mean+/-SD discriminant function scores were 2.9+/-1.6, 1.8+/-2.2, -0.1+/-2.8, -1.2+/-2.3, and -2.3+/-3.0 for isografts and allograft ISHLT grades 0, I, II, and III, respectively (Spearman rank-order correlation -0.6; P<0.001, test for trend). Cyclosporine had no detectable effect on the spectra.

CONCLUSIONS

The correlation between changes in autofluorescence spectra and ISHLT rejection grade strongly supports the possibility of catheter-based, fluorescence-guided surveillance of rejection.

The pulmonary venous systolic flow pulse--its origin and relationship to left atrial pressure

OBJECTIVES

The purpose of this study was to determine the origin of the pulmonary venous systolic flow pulse using wave-intensity analysis to separate forward- and backward-going waves.

BACKGROUND

The mechanism of the pulmonary venous systolic flow pulse is unclear and could be a "suction effect" due to a fall in atrial pressure (backward-going wave) or a "pushing effect" due to forward-propagation of right ventricular (RV) pressure (forward-going wave).

METHODS

In eight patients during coronary surgery, pulmonary venous flow (flow probe), velocity (microsensor) and pressure (micromanometer) were recorded. We calculated wave intensity (dP x dU) as change in pulmonary venous pressure (dP) times change in velocity (dU) at 5 ms intervals. When dP x dU > 0 there is a net forward-going wave and when dP x dU < 0 there is a net backward-going wave.

RESULTS

Systolic pulmonary venous flow was biphasic. When flow accelerated in early systole (S1), pulmonary venous pressure was falling, and, therefore, dP x dU was negative, -0.6 +/- 0.2 (x +/- SE) W/m2, indicating a net backward-going wave. When flow accelerated in late systole (S2), pressure was rising, and, therefore, dP x dU was positive, 0.3 +/- 0.1 W/m2, indicating a net forward-going wave.

CONCLUSIONS

Pulmonary venous flow acceleration in S1 was attributed to a net backward-going wave secondary to a fall in atrial pressure. However, flow acceleration in S2 was attributed to a net forward-going wave, consistent with propagation of the RV systolic pressure pulse across the lungs. Pulmonary vein systolic flow pattern, therefore, appears to be determined by right- as well as left-sided cardiac events.

Left ventricular mass index increase in early renal disease: impact of decline in hemoglobin

Cardiovascular disease occurs in patients with progressive renal disease both before and after the initiation of dialysis. Left ventricular hypertrophy (LVH) is an independent predictor of morbidity and mortality in dialysis populations and is common in the renal insufficiency population. LVH is associated with numerous modifiable risk factors, but little is known about LV growth (LVG) in mild-to-moderate renal insufficiency. This prospective multicenter Canadian cohort study identifies factors associated with LVG, measured using two-dimensional-targeted M-mode echocardiography. Eight centers enrolled 446 patients, 318 of whom had protocol-mandated clinical, laboratory, and echocardiographic measurements recorded. We report 246 patients with assessable echocardiograms at both baseline and 12 months with an overall prevalence of LVH of 36%. LV mass index (LVMI) increased significantly (>20% of baseline or >20 g/m2) from baseline to 12 months in 25% of the population. Other than baseline LVMI, no differences in baseline variables were noted between patients with and without LVG. However, there were significant differences in decline of Hgb level (-0.854 v -0.108 g/dL; P = 0.0001) and change in systolic blood pressure (+6.50 v -1.09 mm Hg; P = 0.03) between the groups with and without LVG. Multivariate analysis showed the independent contribution of decrease in Hgb level (odds ratio [OR], 1.32 for each 0.5-g/dL decrease; P = 0.004), increase in systolic blood pressure (OR, 1.11 for each 5-mm Hg increase; P = 0.01), and lower baseline LVMI (OR, 0.85 for each 10-g/m2; P = 0.011) in predicting LVG. Thus, after adjusting for baseline LVMI, Hgb level and systolic blood pressure remain independently important predictors of LVG. We defined the important modifiable risk factors. There remains a critical need to establish optimal therapeutic strategies and targets to improve clinical outcomes.

Significance of serum antibodies reactive with flavoprotein subunit of succinate dehydrogenase in thyroid associated orbitopathy

AIMS

Thyroid associated orbitopathy (TAO) is an autoimmune disorder of extraocular muscles and orbital connective tissue. Identification of the principal target antigens would help the understanding of the pathogenesis of the disease and possibly lead to the development of specific therapies in the future. The purpose of this study was to measure serum antibodies against the flavoprotein subunit of succinate dehydrogenase in patients with TAO and correlate their presence with factors of TAO.

METHODS

Sera of patients with active TAO of 6 months' duration or less were tested for antibodies against the flavoprotein subunit of succinate dehydrogenase. Clinical data were obtained by retrospective review of patients' charts. Enzyme linked immunosorbent assay was used to test sera for serum antibodies against purified succinate dehydrogenase.

RESULTS

38 patients with TAO and 32 healthy age and sex matched controls were included in the study. Anti-flavoprotein antibodies were detected in 24 out of 38 patients with TAO (63.16%) and in five out of 32 healthy controls (15.63%) (p<0.01). Neither age, sex, duration of thyroid disease, thyroid status, treatment of thyroid disease, smoking history, duration of orbitopathy, activity of orbitopathy, nor the presence of lid retraction were significantly associated with the presence of serum anti-flavoprotein antibodies (p>0.05). However, the total number of rectus muscles affected in both eyes of the patients was significantly correlated with the finding of a positive antibody test (p<0.05).

CONCLUSIONS

Serum antibodies reactive with the flavoprotein subunit of succinate dehydrogenase are associated with extraocular muscle involvement in active TAO of recent onset.

Left ventricular morphology in elite female resistance-trained athletes

Long-term resistance training as performed by elite female resistance-trained athletes appears to be an insufficient stimulus to alter left ventricular cavity size, wall thickness, or estimated mass.

Rebuilding the healthcare system in Mostar: challenge and opportunity

A basic premise of this article is that the political and ethnic division of the city of Mostar imperils community health planning efforts beyond those normally encountered in the aftermath of war. Bosnia and Herzegovina is divided among ethnic groups, and the city of Mostar is further subdivided between the Croatian and Muslim interest groups. In that respect, Mostar presents a very special challenge to those planning the reconstruction of the health care delivery infrastructure. A new healthcare delivery plan was organized by the Federation of Bosnia and Herzegovina in 1996. This paper examines obstacles involved in implementing that plan in light of some epidemiological indicators of current health conditions.

Arterial embolism complicating implantable cardioverter defibrillator shocks with normal ventricular function

A 69-year-old man developed an embolus to his right femoral artery 24 h following the insertion of an implantable cardioverter defibrillator (ICD), with multiple shocks administered in the early postoperative period. He had nonobstructive hypertrophic cardiomyopathy with normal left ventricular function and no evidence of left atrial or ventricular thrombus seen on pre- or postoperative transthoracic echocardiography. There was no evidence of atrial fibrillation documented before or after implantation of the device. He had no other known risk factors for thromboembolic disease. Thromboembolic phenomena as a complication of ICD use have been described but arterial emboli believed related to ICD shocks have not been reported in patients without impaired systolic function.

Ventricular rupture during coronary angioplasty for acute reinfarction

Ventricular rupture following acute myocardial infarction usually leads to hemopericardium and death from cardiac tamponade. We describe a patient who had cardiac rupture during direct angioplasty for reinfarction 3 days following an acute anterior myocardial infarction. In this instance, ventricular rupture presented as a severe form of reperfusion injury. The current literature on reperfusion injury and risk factors for cardiac rupture are discussed.

Anterior visual pathway gliomas

The benign anterior visual pathway glioma undoubtedly is the most controversial subject in neuro-ophthalmology. Although we are persuaded by the evidence that they are true neoplasms rather than hamartomas, the controversy over their biological nature seems moot, as they have a low growth potential. That is not to say that serious visual loss is not common or that, in some cases (especially among those lesions arising in the chiasmalhypothalamic region), tumor-related death and disability cannot occur. These posteriorly located lesions may cause hydrocephalus, and shunting is required if that occurs. The need for shunting in such cases may be the only point on which experts agree. What has yet to be established is whether any of the forms of therapy now available for anterior visual pathway gliomas without hydrocephalus is better than no treatment. Surgery, radiation, and chemotherapy all carry risks. A randomized, controlled study, if feasible, would be apt to settle the issue. The low incidence of these tumors might frustrate attempts to complete such an investigation in a reasonable period. A team of physicians should manage patients with benign anterior visual pathway gliomas. Radiologists, neurologists, neurosurgeons, radiation oncologists, pediatricians, endocrinologists, and oncologists all have a role, but the neuro-ophthalmologist should be the leader. Neuro-ophthalmologists are in the unique position of being able to recognize and document changes in the patient's visual function. Furthermore, neuro-ophthalmologists, being disinterested, are free to choose without bias from among the various management options. The malignant anterior visual pathway glioma is not a subject of controversy. The clinical features at presentation are apt to be misinterpreted as evidence of an inflammatory or ischemic neuropathy rather than the announcement of a fatal brain tumor. Though these patients receive radiotherapy and chemotherapy, these measures have not improved survival significantly, and the outcome is uniformly fatal. The only positive thing that can be said about the malignant gliomas of the anterior visual pathway is that they are so rare.

Small hemodynamic effect of typical rapid volume infusions in critically ill patients

OBJECTIVES

To determine what volumes are commonly used for rapid volume infusions in critically ill patients admitted to the intensive care unit (ICU) for > 12 hrs; and to determine the effectiveness of a typical rapid volume infusion in producing hemodynamic change and increasing left ventricular end-diastolic volume.

DESIGN

A prospective survey of clinical practice (part 1) and a prospective clinical investigation (part 2).

SETTING

Two hospital ICUs (11 and six beds) of which one is university affiliated.

PATIENTS

Critically ill patients admitted to the ICU for > 12 hrs.

INTERVENTIONS

Infusion of 500 mL of normal saline over 5 to 10 mins.

MEASUREMENTS AND MAIN RESULTS

For 1 month, we recorded the volume and composition of all volume infusions given as a rapid bolus in patients admitted to the ICU for > 12 hrs. We then measured the effected the median rapid volume infusion in a subset of 13 patients by measuring hemodynamics (using arterial and pulmonary artery flotation catheters) and left ventricular end-diastolic area (using transgastric short-axis views from transesophageal echocardiograms). During 470 patient days, 159 rapid volume infusions were administered. The average rapid volume infusion administered was 390 +/- 160 mL (median 500; interquartile range 250 to 500). Crystalloid solutions were used for two thirds of the rapid volume infusions and colloid solutions were used for one third of the rapid volume infusions. The rapid volume infusion of 500 mL of saline did not significantly increase mean arterial pressure (78.0 +/- 11.9 to 79.3 +/- 14.6 mm Hg), cardiac index (4.3 +/- 1.7 to 4.6 +/- 1.8 L/min/m2), right atrial pressure (11.1 +/- 3.8 to 12.4 +/- 3.3 mm Hg), left ventricular end-diastolic area (8.6 +/- 1.7 to 9.1 +/- 1.8 cm2/m2), or left ventricular end-systolic area (3.5 +/- 1.5 to 3.6 +/- 1.5 cm2/m2). Pulmonary artery occlusion pressure increased slightly but significantly from 12.9 +/- 3.4 to 14.7 +/- 3.3 mm Hg (p < .05).

CONCLUSIONS

After patients are admitted to the ICU for > 12 hrs, rapid volume infusions are common therapeutic interventions but the rapid volume infusions are typically small. The effect of a typical rapid volume infusion on hemodynamics and left ventricular areas in these patients is surprisingly small.

Population-based study of risk of venous thromboembolism associated with various oral contraceptives

BACKGROUND

Four studies published since December, 1995, reported that the incidence of venous thromboembolism (VTE) was higher in women who used oral contraceptives (OCs) containing the third-generation progestagens gestodene or desogestrel than in users of OCs containing second-generation progestagens. However, confounding and bias in the design of these studies may have affected the findings. The aim of our study was to re-examine the association between risk of VTE and OC use with a different study design and analysis to avoid some of the bias and confounding of the earlier studies.

METHODS

We used computer records of patients from 143 general practices in the UK. The study was based on the medical records of about 540,000 women born between 1941 and 1981. All women who had a recorded diagnosis of deep-vein thrombosis, venous thrombosis not otherwise specified, or pulmonary embolus during the study period, and who had been treated with an anticoagulant were identified as potential cases of VTE. We did a cohort analysis to estimate and compare incidence of VTE in users of the main OC preparations, and a nested case-control study to calculate the odds ratios of VTE associated with use of different types of OC, after adjustment for potential confounding factors. In the case-control study, we matched cases to controls by exact year of birth, practice, and current use of OCs. We used a multiple logistic regression model that included body-mass index, number of cycles, change in type of OC prescribed within 3 months of the event, previous pregnancy, and concurrent disease.

FINDINGS

85 women met the inclusion criteria for VTE, two of whom were users of progestagen-only OCs. Of the 83 cases of VTE associated with use of combined OCs, 43 were recorded as deep-vein thrombosis, 35 as pulmonary thrombosis, and five as venous thrombosis not otherwise specified. The crude rate of VTE per 10,000 woman-years was 4.10 in current users of any OC, 3.10 in users of second-generation OCs, and 4.96 in users of third-generation preparations. After adjustment for age, the rate ratio of VTE in users of third-generation relative to second-generation OCs was 1.68 (95% CI 1.04-2.75). Logistic regression showed no significant difference in the risk of VTE between users of third-generation and second-generation OCs. Among users of third-generation progestagens, the risk of VTE was higher in users of desogestrel with 20 g ethinyloestradiol than in users of gestodene or desogestrel with 30 g ethinyloestradiol. With all second-generation OCs as the reference, the odds ratios for VTE were 3.49 (1.21-10.12) for desogestrel plus 20 g ethinyloestradiol and 1.18 (0.66-2.17) for the other third-generation progestagens.

INTERPRETATION

The previously reported increase in odds ratio associated with third-generation OCs when compared with second-generation products is likely to have been the result of residual confounding by age. The increased odds ratio associated with products containing 20 micrograms ethinyloestradiol and desogestrel compared with the 30 micrograms product is biologically implausible, and is likely to be the result of preferential prescribing and, thus, confounding.

Serum from patients with chronic renal insufficiency alters growth characteristics and ANP mRNA expression of adult rat cardiac myocytes

Left ventricular hypertrophy is very prevalent among patients with renal insufficiency. Known hypertrophic factors, such as systemic hypertension, do not adequately account for the prevalence of left ventricular hypertrophy in these patients. Circulating growth factors may stimulate cardiomyocyte growth and contribute to the development of left ventricular hypertrophy. The effects of sera from patients with (n = 30) and without (n = 5) chronic renal insufficiency on the growth of cultured adult cardiomyocytes were compared. An adult rat cardiomyocyte primary culture system was established with a high purity of cardiomyocyte population as confirmed by immunocytochemical staining of cardiac contractile proteins. Myocytes responded with increased [3H]thymidine incorporation when treated with angiotensin II, epidermal growth factor, hydrocortisone and insulin, and with increased [3H]phenylalanine incorporation when treated with parathormone, isoproterenol, phenylephrine and insulin. Renal insufficiency serum stimulated [3H]thymidine incorporation was 1.5 times that of the control (P < 0.02) and also tended to increase incorporation of [3H]phenylalanine compared to the control (P = N.S.). Increased [3H]thymidine incorporation by renal insufficiency serum did not correlate with serum insulin, parathormone or glucose in the renal insufficiency patients. A quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method was used to measure renal insufficiency serum-induced atrial natriuretic peptide mRNA expression in cultured cardiomyocytes. Atrial natriuretic peptide (ANP) mRNA was increased 1-3-fold in cardiomyocytes treated with renal insufficiency sera in comparison to control sera. These data suggest that circulating growth factor(s) may contribute to the development of cardiac hypertrophy in patients with renal insufficiency.

Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients

PURPOSE

Recent observations have highlighted errors in the thermodilution technique of measuring cardiac output. Thus, cardiac output measurements using transesophageal echocardiography and the Fick method were compared with simultaneous thermodilution measurements.

METHODS

In 13 mechanically ventilated critically ill patients, cardiac output was determined simultaneously using (1) transesophageal echocardiography (COTEE, (2) the Fick method (COFICK, and (3) thermodilution (COTD immediately before and after a rapid infusion of 500 mL of saline. Left ventricular end-diastolic and end-systolic areas were measured using the transesophageal echocardiographic transgastric short axis view, and COTEE was calculated from the corresponding volumes. Absolute cardiac output values and the changes from before to after saline infusion (delta CO) were compared using analysis of variance, linear regression, and the Bland and Altman method.

RESULTS

There were no significant differences between COTEE (8.0 +/- 3.4), COFICK (8.4 +/- 3.3), and COTD (8.3 +/- 3.0) or between delta COTEE, delta COFICK, and delta COTD using analysis of variance. However, correlations between COTEE and COTD (r2 = 0.46; P < .00001), COFICK and COTD (r2 = 0.46; P < .0001), and COTEE and COFICK (r2 = 0.42; P < .0001) were only moderately good. Using the method of Bland and Altman, the mean difference (+/-2 standard deviations) between COTEE and COTD was 0.3 +/- 4.3 L/min, between COFICK and COTD was -1.0 +/- 3.8 L/min, and between COTEE and COFICK was 0.6 +/- 5.6 L/min, whereas the difference between delta COTEE and delta COTD was 0% +/- 26%, between delta COFICK and delta COTD was 9% +/- 46%, and between delta COTEE and delta COFICK was 8% +/- 39%.

CONCLUSIONS

There are substantial differences in cardiac output as measured by these three methods, best demonstrated using the method of Bland and Altman. The variability of cardiac output and its derivatives (eg, oxygen delivery) should be borne in mind when making clinical decisions on individual patients.

Melanin granule model for laser-induced thermal damage in the retina

An analytical model for thermal damage of retinal tissue due to absorption of laser energy by finite-sized melanin granules is developed. Since melanin is the primary absorber of visible and near-IR light in the skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are modeled as absorbing spheres surrounded by an infinite medium of water. Analytical solutions to the heat equation result in computations that are quick and accurate. Moreover, the model does not rely on symmetric beam profiles, and so arbitrary images can be studied. The important contribution of this model is to provide a more accurate biological description of sub-millisecond pulse exposures than previous retinal models, while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vaporization as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.

Prevalent left ventricular hypertrophy in the predialysis population: identifying opportunities for intervention

Left ventricular hypertrophy (LVH) is present in over 70% of patients commencing dialysis. It is an independent risk factor for cardiac death, which is the cause of death in approximately 45% of patients in dialysis. The prevalence of LVH in patients earlier in the course of renal insufficiency is unknown. As part of a prospective longitudinal study evaluating the progression of comorbid diseases in patients with progressive renal disease, we evaluated LVH. In 175 consecutive patients attending a renal insufficiency clinic we obtained technically adequate echocardiograms and estimated left ventricular mass index (LVMI) using two-dimensional targeted M-mode echocardiography. We calculated LVMI using the American Society of Echocardiography cube formula method regressed to anatomic validation. The population consisted of 115 men and 60 women ranging in age from 20 to 82 years (mean age, 51.5 years). The mean creatinine was 403 +/- 207 micro mol/L (+/-SD), representing a creatinine clearance (Ccr) of 25.5 +/- 17 mL/min. Left ventricular hypertrophy was defined as LVMI greater than 131 g/m(2) in men and greater than 100 g/m(2) in women, and was present in 38.9% of the population studied. We demonstrate that the prevalence of LVH increased with progressive renal decline: 26.7% of patients with Ccr greater than 50 mL/min had LVH, 30.8% of those with Ccr between 25 and 49 mL/min had LVH, and 45.2% of patients with severe renal impairment (Ccr <25 L/min) had LVH (P = 0.05). The mean LVMI was significantly different among the three groups (97.5 g/m(2) v 114.4 g/m(2), respectively; P < 0.001). Univariate analyses revealed that age, hemoglobin, systolic blood pressure and Ccr were significantly different between the groups with and without LVH. The logistic regression model confirmed the findings of the univariate analysis: an increase in age of 5 years was associated with an increase of 3% in risk of LVH (P = 0.0094), as was an increase in systolic blood pressure of 5 mm Hg (P = 0.0018). For each 10 g/L decrease in hemoglobin, the risk of LVH increased by 6% (P = 0.0062), and for each 5 mL/min decline in Ccr the risk increased by 3% (P = 0.0168). We demonstrate the high prevalence of LVH in patients with renal insufficiency prior to the need for dialysis, which is associated with severity of renal impairment, and identify two modifiable factors (systolic blood pressure and anemia) as important predictors of LVH. We suggest that future studies should focus on interventions aimed at attenuating the impact of these factors.

Laser induced bubble formation in the retina

BACKGROUND AND OBJECTIVE

The immediate thermodynamic effects of absorption of a laser pulse in the retina are theoretically studied to understand underlying physical damage mechanisms at threshold fluences. Damage is most likely to occur at threshold levels in the retinal pigment epithelium due to the strong absorption by the melanosomes.

METHODS

The retinal pigment epithelium is modeled as an aqueous environment with absorption occurring at small spherical sites with absorption coefficients representative of melanosomes. For laser pulse durations of less than 10(-6) seconds, heat conduction is negligible during energy deposition and the resulting large energy density in the melanosomes will cause vaporization of the medium immediately surrounding a melanosome.

RESULTS

We developed expressions for calculating the size of bubbles produced as a function of pulse characteristics and melanosome properties. We show that for pulse durations between 10(-6) and 10(-9) seconds, bubble formation will occur for laser fluences that are smaller than those required to cause Arrhenius-type thermal damage.

CONCLUSION

Bubble formation is likely to be the mechanism of threshold damage to the retina for laser pulses durations in the time regime between 10(-6) and 10(-9) seconds.

A potential clinical method for calculating transmural left ventricular filling pressure during positive end-expiratory pressure ventilation: an intraoperative study in humans

OBJECTIVES

This study sought to investigate whether right atrial pressure could be used to estimate pericardial pressure during positive end-expiratory pressure (PEEP).

BACKGROUND

Because of elevated intrathoracic pressure during PEEP, pulmonary capillary wedge pressure may not accurately reflect left ventricular preload. An estimate of pericardial pressure during PEEP would allow assessment of transmural filling pressure.

METHODS

In eight patients, at the start of cardiac surgery, pericardial and pleural pressures were recorded by balloon transducers placed over the anterolateral left ventricular wall. We also recorded intravascular pressures and left ventricular short-axis area by transesophageal echocardiography.

RESULTS

A stepwise increase in PEEP from 0 to 15 cm H2O caused a linear increase in pleural pressure from 0.3 +/- 0.6 (mean +/- SEM) to 6.1 +/- 0.8 mm Hg (p < 0.01). Pericardial pressure increased from 2.3 +/- 0.5 to 5.9 +/- 0.6 mm Hg (p < 0.01). The correlation between right atrial (Pra) and pericardial pressure (Pperic) was good: Pra = 0.85 x Pperic + 1.8, r = 0.77. The correlation between changes in right atrial pressure and in pericardial pressure was better: delta Pra = 0.96 x delta Pperic -0.2, r = 0.97. Pulmonary capillary wedge pressure increased with PEEP (p < 0.05), whereas left ventricular area decreased (p < 0.05). However, there was a progressive reduction in transmural pressure, calculated as wedge pressure minus pericardial pressure (p < 0.05), and in transmural pressure, estimated as wedge pressure minus right atrial pressure (p < 0.05). The estimated transmural filling pressure correlated (r = 0.86) with end-diastolic area.

CONCLUSIONS

The present observations suggest that right atrial pressure may be used to estimate changes in pericardial pressure with PEEP and that pulmonary capillary wedge pressure minus right atrial pressure is a potentially clinically useful approximation of transmural filling pressure.

Effect of lung inflation and sternotomy direction on pleural space violation

Patients often are disconnected temporarily from the ventilator before sternotomy to avoid entering the pleural space with the sternal saw. Although this practice is widespread, it is based on questionable physiologic principles. To evaluate the efficacy of this maneuver in reducing the incidence of pleural space violation with first-time sternotomy, 126 cardiac patients were randomized prospectively to either lungs inflated or deflated during sternotomy with the surgeon blinded to the particular assignment. The incidence of pleural space violation overall was 12%, occurring in 15% of patients with deflated lungs and in 9% of those with inflated lungs (p = 0.455 by chi 2 test). Examining the effect of the direction of sternotomy on pleural space entry revealed a 4% incidence with sternotomy starting at the xiphoid versus a 21% incidence with sternotomy starting at the sternal notch (p = 0.009 by chi 2 test). Preexisting hyperinflation of the lungs as evaluated by chest radiograms did not influence the incidence of pleural space violation. To reduce pleural space violation, sternotomy should be performed from the xiphoid to the sternal notch. More importantly, disconnecting the patient from the ventilator does not reduce pleural space violation with sternotomy and its further use is not indicated. These findings are discussed in the context of relevant heart-lung pathophysiology.

The Drosophila tissue-specific factor Grainyhead contains novel DNA-binding and dimerization domains which are conserved in the human protein CP2

We have mapped the regions in the Drosophila melanogaster tissue-specific transcription factor Grainyhead that are required for DNA binding and dimerization. These functional domains correspond to regions conserved between Grainyhead and the vertebrate transcription factor CP2, which we show has similar activities. The identified DNA-binding domain is large (263 amino acids) but contains a smaller core that is able to interact with DNA at approximately 400-fold lower affinity. The major dimerization domain is located in a separate region of the protein and is required to stabilize the interactions with DNA. Our data also suggest that Grainyhead activity can be modulated by an N-terminal inhibitory domain.

Mobile Minos elements from Drosophila hydei encode a two-exon transposase with similarity to the paired DNA-binding domain

Elements related to the Tc1-like Minos mobile element have been cloned from Drosophila hydei and sequenced. Southern blot and sequence analyses show that (i) the elements are actively transposing in the Drosophila hydei germ line, (ii) they are characterized by a striking degree of sequence and size homogeneity, and (iii) like Tc1, they insert at a TA dinucleotide that is probably duplicated during the process. The nucleotide sequences of two elements, Minos-2 and Minos-3, differ at only one position from each other and contain two nonoverlapping open reading frames that are separated by a putative 60-nucleotide intron. The amino-terminal part of the Minos putative transposase shows sequence similarity to the paired DNA-binding domain. Forced transcription of a modified Minos element that was introduced into the Drosophila melanogaster germ line by P element-mediated transformation resulted in the production of accurately spliced polyadenylylated RNA molecules. It is proposed that Minos-2 and/or Minos-3 may encode an active transposase containing an amino-terminal DNA-binding domain that is distantly related to the paired DNA-binding domain.