Fine structure of highly charged excitons in semiconductor quantum dots

An exciton in a symmetric semiconductor quantum dot has two possible states, one dark and one bright, split in energy by the electron-hole exchange interaction. We demonstrate that for a doubly charged exciton, there are also two states split by the electron-hole exchange, but both states are now bright. We also uncover a fine structure in the emission from the triply charged exciton. By measuring these splittings, and also those from the singly charged and doubly charged biexcitons, all on the same quantum dot, we show how the various electron-hole exchange energies can be measured without having to break the symmetry of the dot.

Efficacy of linear and convex transducers for ultrasound-guided transvaginal follicle aspiration

A new device was developed to hold linear transducers for transvaginal follicle aspiration. Efficacy of follicle aspiration was compared using a linear 6 MHz and a convex 5 MHz transducer. Fifty-five cows were submitted to follicle aspiration at random days of the estrous cycle. Aspirations were conducted with linear (n=28) and convex (n=38) transducers with 18 G needles at a negative pressure corresponding to 13 ml H(2)O/min. A greater number of follicles were aspirated using convex than to linear probe (12.4 versus 7.8, respectively, P<0.05). Mean number of oocytes and recovery rates were similar for convex (5.4 and 48.6%) and linear (4.6 and 59.3%) transducers. Limited space between the linear transducer and needle guide restricted access to some portions of the ovary, reducing the number of follicles aspirated using a linear transducer. The newly developed adaptor allowed greater stability, holding the ovaries firmly against the linear transducer. This diminished mobility permitted a similar number of oocytes to be recovered with both transducers. In conclusion, this new adaptor provided a low cost alternative for routine follicle aspiration and oocyte recovery in cattle.

Detection of epithelial tumour RNA in the plasma of colon cancer patients is associated with advanced stages and circulating tumour cells

BACKGROUND

Although circulating tumour DNA has been detected in patients with different types of cancer, little is known of free RNA in cancer patients.

AIMS

We investigated the presence of RNA from epithelial tumours in plasma from patients with colorectal carcinomas, and its correlation with tumour characteristics and circulating tumour cells.

METHODS

beta-actin mRNA was analysed to assess the viability of plasma RNA in samples from 53 patients with colonic cancer and 25 controls. Subsequently, nested primers were used to detect the presence of cytokeratin 19 (CK19) and carcinoembryonic antigen (CEA) RNA in the same samples. Nine clinicopathological parameters were studied to correlate the molecular and clinical parameters. Additionally, we investigated for micrometastases in blood in 18 of these patients and in 10 of the controls samples.

RESULTS

All samples had detectable quantities of beta-actin RNA. In the controls, one case (4%) was positive for CEA and five (20%) for CK19 RNA; of the 53 patients, 17 cases (32%) were positive for CEA and 39 (73.6%) for CK19 RNA. This was statistically significant (p=0.000001). Advanced stages (p=0.03) and soluble CEA status (p=0.03) were associated with the presence of CEA, CK19, or both RNAs in plasma. Lymph node metastases (p=0.06) and vascular invasion (p=0.07) were almost significant. On the basis of these results, we examined the possible presence of micrometastases in blood in several of these patients. The presence of plasma tumour RNA was found to be associated with circulating tumour cells in blood (p=0.04).

CONCLUSIONS

Epithelial tumour RNA is detectable in plasma from colon cancer patients. This molecular event is associated with advanced stages and circulating tumour cells. Our results could offer new approaches in the diagnosis and monitoring of colon cancer.

Steroidogenesis in cumulus cells of bovine cumulus-oocyte-complexes matured in vitro with BSA and different concentrations of steroids

The present in vitro experiments were designed to evaluate the ability of bovine cumulus-oocyte-complexes (COCs) to produce steroids and also to evaluate the modulatory effects of added estradiol, progesterone and testosterone on the steroidogenic activity of COCs. Considerable estradiol accumulation was observed in the control maturation medium for in vitro maturation of bovine COCs during the 24h of maturation (P<0.05). When testosterone was added to the medium at various concentrations, a slight estradiol accumulation occurred, which, however, was lower (P<0.05) than that observed in the control medium. Slight estradiol accumulation was observed in maturation medium containing progesterone at concentrations of 2.5, 5.0 and 10.0 microg/ml, but these increases were less (P<0.05) than those observed in the control medium. However, in the presence of 1.0 microg/ml progesterone, estradiol accumulation was equal to that of the control medium (P>0.05). Progesterone accumulation (P<0.05) was observed in the control medium for in vitro maturation of bovine COCs. When estradiol was added to the maturation medium, progesterone accumulation was observed, but was significant (P<0.05) only when the medium was supplemented with the lesser concentrations of estradiol utilized in the experiment (1.0 microg/ml). The results demonstrated that (1) cumulus cells of bovine COCs are able to secrete estradiol and progesterone in culture systems for in vitro maturation, and this steroidogenesis is modulated by the steroids progesterone, testosterone and estradiol, and (2) the addition of estradiol to the in vitro maturation medium of bovine oocytes should be reviewed, since cumulus cells of COCs have been demonstrated to secrete estradiol in the maturation medium.

Perceptual ratings for pureed and molded peaches for individuals with and without impaired swallowing

Food molds have been created to alter the appearance of pureed foods by making the pureed consistencies look more like typically prepared foods. This study examined the perceptions of 15 adults with impaired swallowing and 15 adults with nonimpaired swallowing for three different types of pureed peach: a typically prepared pureed peach, a pureed peach with a thickening agent added, and a pureed peach with a thickening agent added and molded to look like peach slices. Results are presented for the attribute ratings of overall liking: liking of taste, texture, and appearance; and ease of chewing and swallowing. The results showed that the adults with impaired swallowing rated the attributes of chewing and swallowing significantly lower (i.e.. more difficult) for each type of puree. Significant differences within samples also were found for the attributes of overall liking and liking of taste. Overall, the pureed peach molds were not perceived favorably for any of the examined attributes. In addition, the molded peach was rated lower (more difficult) in its ease of chewing. The implications of these findings and ideas for further research are discussed.

An anisotropic internal-external bone adaptation model based on a combination of CAO and continuum damage mechanics technologies

In this work, a complete internal-external bone-remodelling scheme is presented and implemented into a finite element code. This model uses a combination of an anisotropic internal remodelling model based on a new Continuum "Damage-Repair" theory and an external adaptation approach that follows the idea, early introduced by Mattheck et al., to simulate the growth behaviour of biological systems, known as CAO method. This combined scheme qualitatively resembles most of the main features of the bone adaptive behaviour, like the bone mass distribution (heterogeneity and porosity), the directional internal structure (anisotropy), the alignment of the microstructure with the constitutive principal directions and these with those of the stress tensor when permanently loaded by a unique stress state (Wolff's law). It is also thermodynamically consistent, fulfilling a principle of minimum mechanical dissipation. Finally, the comparison between the predicted results and the ones obtained by different experimental tests allows us to conclude that this model is able of reproducing qualitatively the global behaviour of bone tissue when subjected to external mechanical loads.

Late outcome of reoperative coronary revascularization on the beating heart

BACKGROUND

Reoperative (redo) coronary artery bypass grafting (CABG) is associated with a higher morbidity and mortality than first-time CABG. An off-cardiopulmonary bypass (off-pump) approach to redo CABG, however, may potentially benefit redo patients. The aim of the present report is to describe the early and long-term clinical outcome of patients who underwent off-pump redo CABG between July 1985 and January 1999 in our institution.

METHODS

Redo patients (n = 138) represented 13% of patients who had off-pump CABG during the period of study (n = 1072). Mean patient age was 63 +/- 12 years, and 67% were men. Surgical approaches included median sternotomy (n = 93, 67%), anterior (n = 20, 15%) and lateral (n = 25, 18%) minimally invasive direct coronary artery bypass (MIDCAB).

RESULTS

Operative mortality was 2% (n = 3). Target lesion re-intervention was 6% (n = 9) Actuarial survival at a mean period of follow-up of 2.5 +/- 1 year (range: 1 month to 11 years) was 83%. Event-free survival (freedom from death, myocardial infarction, and repeat intervention) was 67%. Overall cardiac-related mortality was 10% (n = 14).

CONCLUSION

Off-pump redo CABG can be safely performed with a relatively low mortality rate and a low rate of target lesion revascularization.

Detection of epithelial messenger RNA in the plasma of breast cancer patients is associated with poor prognosis tumor characteristics

PURPOSE

Free plasma RNA has been scarcely studied in patients with cancer. Here we examine the presence of RNA from epithelial tumors in plasma from a series of breast cancer patients and its correlation with tumor characteristics and circulating tumor cells.

EXPERIMENTAL DESIGN

beta-actin mRNA was analyzed to check the viability of plasma RNA in samples from 45 patients with breast cancer and 25 controls. Nested primers were used to detect the presence of cytokeratin 19 (CK19) and Mammaglobin in the same samples. Eleven clinicopathological parameters were studied and correlated with molecular parameters. Additionally, we looked for circulating tumor cells in 16 of these patients and in 10 of the controls.

RESULTS

All samples showed detectable quantities of beta-actin RNA. In controls, 3 cases (12%) were positive for Mammaglobin, and 5 (20%) were positive for CK19 RNA; of the 45 patients, 27 cases (60%) were positive for Mammaglobin, and 22 (49%) were positive for CK19. These differences were statistically significant (P = 0.001). Tumor size (P = 0.01) and proliferative index (P = 0.02) were associated with the presence of Mammaglobin, CK19, or both RNAs in plasma. Pathological stage (P = 0.06) was close to significance. Although a statistical relationship was not demonstrated, 9 of the 10 patients with circulating tumor cells showed epithelial mRNAs in plasma.

CONCLUSIONS

We conclude that epithelial tumor RNA is detectable in plasma from breast cancer patients and that this finding is associated with a probable poor prognosis and circulating tumor cells.

Relationship between follicle size and ultrasound-guided transvaginal oocyte recovery

We evaluated the relationship between follicle size and oocyte recovery (OR) using ultrasound-guided follicle aspiration. Thirty Holstein cows were subjected to OR without gonadotrophic therapy. Oocytes were recovered two to four times from each cow in a total of 67 aspiration sessions. Ovarian follicles with diameters < or =4 mm and >4 mm were aspirated in separated groups. Recovered oocytes from each group were kept separate and submitted to in vitro maturation, fertilization, and culture to the blastocyst stage. A total of 430 follicles were aspirated, of which 154 (35.8%) were from follicles >4 mm and 276 (64.2%) were from follicles < or =4 mm. Seventy-seven oocytes (50%) were recovered from follicles >4 mm and 200 (72.2%) were from follicles < or =4 mm. Nineteen blastocysts were obtained from follicles >4 mm, whereas 45 blastocysts were obtained from follicles < or =4 mm. Recovery rate was greater (P<0.01) in follicles < or =4 mm. Oocyte quality, cleavage rate and blastocyst development did not differ between different follicle sizes. Routine aspiration of small follicles (< or =4 mm) could increase the number of oocytes available for in vitro development.

Influence of the nonionic surfactant Brij 35 on the bioavailability of solid and sorbed dibenzofuran

The effect of the nonionic surfactant Brij 35 on the bioavailability of solid and Teflon-sorbed dibenzofuran for Sphingomonas sp. strain HH19k was studied in simple model systems. Growth with dibenzofuran and dibenzofuran-specific oxygen uptake in surfactant-free media and with Brij 35 above the critical micelle concentration (cmc) were compared with dissolution and desorption in the absence of bacteria. Brij 35 accelerated dissolution and biodegradation of solid dibenzofuran by a factor of 2. It also enhanced the initial desorption rate of dibenzofuran from Teflon by this factor. Continuously decreasing desorption rates were attributed to slow diffusion of dibenzofuran inside Teflon, leading to depletion of dibenzofuran in the exterior of the Teflon particles. Surprisingly, Brij 35 slowed the initial biodegradation of desorbing dibenzofuran. We propose two processes that led to low bioavailability of sorbed dibenzofuran in the presence of surfactant. First, desorbing dibenzofuran rapidly accumulated in surfactant micelles, leading to reduced truly water-dissolved dibenzofuran concentration as the factor controlling the biodegradation rate. Second, Brij 35 suppressed the contact between bacteria and Teflon. This increased the average diffusion distance of dibenzofuran to the bacteria, which in turn flattened the gradient of the dissolved dibenzofuran concentration between the sorbent and the cells as the driving force for desorption.

Complete replacement of the mitochondrial genotype in a Bos indicus calf reconstructed by nuclear transfer to a Bos taurus oocyte

Due to the exclusively maternal inheritance of mitochondria, mitochondrial genotypes can be coupled to a particular nuclear genotype by continuous mating of founder females and their female offspring to males of the desired nuclear genotype. However, backcrossing is a gradual procedure that, apart from being lengthy, cannot ascertain that genetic and epigenetic changes will modify the original nuclear genotype. Animal cloning by nuclear transfer using host ooplasm carrying polymorphic mitochondrial genomes allows, among other biotechnology applications, the coupling of nuclear and mitochondrial genotypes of diverse origin within a single generation. Previous attempts to use Bos taurus oocytes as hosts to transfer nuclei from unrelated species led to the development to the blastocyst stage but none supported gestation to term. Our aim in this study was to determine whether B. taurus oocytes support development of nuclei from the closely related B. indicus cattle and to examine the fate of their mitochondrial genotypes throughout development. We show that indicus:taurus reconstructed oocytes develop to the blastocyst stage and produce live offspring after transfer to surrogate cows. We also demonstrate that, in reconstructed embryos, donor cell-derived mitochondria undergo a stringent genetic drift during early development leading, in most cases, to a reduction or complete elimination of B. indicus mtDNA. These results demonstrate that cross-subspecies animal cloning is a viable approach both for matching diverse nuclear and cytoplasmic genes to create novel breeds of cattle and for rescuing closely related endangered cattle.

Wild type p73 overexpression and high-grade malignancy in breast cancer

The overexpression of wild type p73 is the most frequent alteration of p73 in malignancies. We investigated, in 70 breast carcinomas, p73 mRNA expression and its relationship to p53 mutations, determined by an immunohistochemical method, and loss heterozygosity (LOH) status of the 1p36 region, together with its possible implication in the pathogenesis of breast carcinomas. LOH, amplifying DNA by PCR using 5 markers, of 1p36 region (one intragenic to p73 gene) was found in 17% of cases but no significant correlation was observed with p73 overexpression. p53 positive immunostaining was present in 33% of breast carcinomas, and these exhibited a statistically significant relation with p73 overexpressed tumors. Overexpression of p73 mRNA was observed in 19 tumors (27%). The analysis of cases with p73 overexpression and cases with normal mRNA expression, in terms of age and pathologic characteristics of the tumors showed a significant association of p73 overexpression and tumors with lymph node metastases, vascular invasion and higher pathologic stage. These results suggest that p73 overexpression is a molecular alteration that could be implicated in the tumorigenesis of breast carcinomas and, eventually, in a poor clinical behavior.

Minimally invasive coronary revascularization in women: A safe approach for a high-risk group

PURPOSE

Female gender has been shown to be an independent risk factor for mortality in coronary artery bypass graft (CABG) surgery. This report analyzes our early outcomes in 304 women who underwent off-pump coronary artery bypass (OPCAB) surgery at the Washington Hospital Center (Washington, DC) over the last 3 years to determine whether this is a safe approach for coronary bypass in women.

METHODS

A retrospective review of 5528 cases of CABG bypass (on-pump) and 840 cases of OPCAB surgery, from June 1996 to July 1999, was performed. Women accounted for 1527 (27.6%) of the on-pump bypass cases and 304 (36.2%) of the OPCABs. All cases without cardiopulmonary bypass were included, with the majority of the most recent cases being multivessel revascularization. The data for analysis were obtained from our cardiac surgery database and included cases from all surgeons operating at the Washington Hospital Center, although the majority of off-pump cases were performed by only a few of these surgeons.

RESULTS

The two groups were similar with respect to urgent cases, redos, and other comorbities including preoperative congestive heart failure, peripheral vascular disease, transient ischemic attack (TIA), cerebral vascular accident, and previous myocardial infarction. The mean age for the two groups was similar, 67 years for the off-pump group and 66 years for the on-pump group. The absolute number of all off-pump cases increased each year (from 175 to a total of 373), representing a corresponding increase in percentage of all coronary artery bypass procedures (from 9% to 16%). Of the total number of patients undergoing CABG, the percentage of women who underwent OPCAB doubled from 3% to 6% over the time period analyzed. The percentage of single-vessel cases in the off-pump group fell from 88% to 41% as multivessel bypasses became more routine However, the percentage of patients aged > 75 years was greater for the off-pump group (30%) than for the on-pump group (24%). Otherwise, the two groups differed only in diabetic disease (36% off-pump compared with 46% on-pump; p = 0.001) and previous transcatheter therapy (38% off-pump compared with 29% on-pump; p = 0.003). Patients who had OPCABs received fewer postoperative transfusions (40%) than the on-pump group (59%; p < 0.001). The off-pump group also had fewer neurological complications in the form of TIAs or strokes (0.3%) compared with the on-pump group (3.5%; p = 0.001). The mortality rate was 2.3% off -pump versus 4.1% on pump but did not reach statistical significance in this study (p =.12).

CONCLUSION

Myocardial revascularization in women can be performed safely without cardiopulmonary bypass. In our series, the mortality for women receiving off-pump revascularization was lower than the on-pump cohorts despite an older age and higher incidence of diabetes. Although the absolute mortality rates did not reach statistical significance, we were encouraged that the mortality rate for women operated on without CPB dropped to the mortality rate typically seen in men. We also observed a favorable tendency in the off-pump group for a shorter length of stay and a lower incidences of transient ischemic attacks, strokes, post-op bleeding, and blood transfusions. A larger series of patients with multivariate analysis and/or a prospective trial will need to be analyzed in order to confirm our findings.

DNA damage after chemotherapy correlates with tumor response and survival in small cell lung cancer patients

To explore the induction of chemotherapy (CT) DNA damage and its correlation with tumor response and patient survival, we undertook the present study in 20 small cell lung cancer (SCLC) patients. All patients underwent the same treatment based on CT courses of carboplatin and etoposide. Blood samples were taken before and immediately after CT and every 12 weeks during follow-up. Nuclear DNA damage was determined through the variations in three mitochondrial pseudogene mutations in DNA of peripheral blood mononuclear cells. They were detected by mutation-specific PCR and assessed by a semiquantitative method. The relative level of mutation rose after chemotherapy in all cases. Among the 11 patients (55%) with higher relative levels of mutations, 9 (82%) of them achieved a complete response. In contrast, of the 9 patients (45%) with lower relative levels of mutations, only 2 (18%) achieved a complete response, displaying a statistically significant difference (P=0.02). The overall survival for patients with marked genomic damage was 18 months (range 10-24), and for patients with low degree of DNA damage, it was 12 months (range 5-15) (P=0.002). Genomic damage detected after chemotherapy treatment correlates positively with tumor response and patient survival.

Determinants of in-hospital mortality in women with acute myocardial infarction who underwent primary coronary angioplasty

INTRODUCTION

According to recent data, women have a greater risk of dying from an acute coronary event. The determinants of this ominous prognosis are not completely understood. Preliminary analysis of our data suggested that this poorer prognosis is also observed in the subgroup of patients with acute myocardial infarction submitted to direct coronary angioplasty (PTCA). This finding prompted us to investigate gender differences and their determinants in this particular context.

OBJECTIVE

To identify risk factors associated with the greater in-hospital mortality of women with acute infarction who underwent PTCA.

METHODS

One hundred and forty-five consecutive patients with acute myocardial infarction who underwent direct PTCA in the same hospital were studied retrospectively. Data were collected from the database of the catheterisation laboratory and from clinical files. The following parameters were analysed: in-hospital mortality, age, prevalence of diabetes mellitus, history of coronary heart disease, time elapsed from beginning of symptoms to coronary intervention, peak values of CK and MB-CK, number of coronary arteries with significant disease at angiography, culprit lesion localisation, and prevalence of shock on admission. For statistical analysis, cross-tabulation (Pearson x2) and comparison of means (Student's t test) were employed when appropriate; an error of 5% was admitted for the rejection of the null hypothesis.

RESULTS

Women (n = 39) represented 26.9% of sample. In hospital mortality was 28.2% (n = 11) for women and 11.3% (n = 12) for men (p = 0.014). The prevalence of coronary heart disease before the current acute event, the time elapsed from beginning of symptoms to coronary intervention, and maximum values of CK and MB-CK were similar in both genders. Differences between women and men were found as regards the following variables (women vs men): age (61.7 +/- 10 vs 56.1 +/- 12.6 years), prevalence of left main disease (15.3 vs 1.9%) and prevalence of shock (41 vs 17%) and diabetes (38.7 vs 13.6%). Considering women and men who died, only disease severity as evaluated by the number of vessels involved distinguished both genders (p = 0.05).

CONCLUSIONS

In our experience, women admitted with acute myocardial infarction and treated by direct PTCA are, on average, older than men and have a greater prevalence of shock at admission, of left main disease and of diabetes, and more severe coronary artery disease. In the present series and as regard in-hospital mortality, disease severity as evaluated by the number of vessels involved is the only variable that discriminates women from men.

Coronary revascularization of the circumflex system: different approaches and long-term outcome

BACKGROUND

Minimally invasive direct coronary artery bypass, without cardiopulmonary bypass, through a left lateral thoracotomy approach (lateral MIDCAB), is a safe alternative to coronary artery bypass surgery using cardiopulmonary bypass (on-pump CABG) of the circumflex system via median sternotomy. However, it is unknown whether lateral MIDCAB may yield an improved long-term outcome over the conventional on-pump median sternotomy approach.

METHODS

We compared the perioperative outcomes of patients undergoing lateral MIDCAB (n = 34) versus conventional on-pump CABG of the circumflex system (n = 16) from June 1996 to July 1999. The two groups were similar with respect to baseline characteristics and risk stratification. Patients who required only one or two grafts for complete revascularization were included.

RESULTS

Lateral MIDCAB patients had a lower need than on-pump CABG patients for intraoperative (12% MIDCAB vs 43% on-pump CABG, p = 0.03) and postoperative transfusions (29% vs 69%, p = 0.01), had fewer neuropsychologic changes (0% vs 19%, p = 0.03), and had a lower rate of postoperative atrial fibrillation (12% vs 44%, p = 0.02). Lateral MIDCAB was also associated with a significantly lower postoperative length of stay (5 +/- 2 vs 7 +/- 3 days, p = 0.02). Actuarial survival at a mean period of follow-up of 19 +/- 11 months was 97% for the lateral MIDCAB versus 88% for the on-pump CABG group (p = 0.6). Event-free survival was 88% for lateral MIDCAB versus 81% for on-pump CABG (p = 0.1).

CONCLUSIONS

Lateral MIDCAB may safely be performed in patients with isolated coronary artery disease of the circumflex system with improved early morbidity and an abbreviated hospital stay compared with conventional median sternotomy on-pump CABG.

Clinicopathological characteristics of breast carcinomas with allelic loss in the p73 region

p73, a new member of the p53 family, has been mapped to chromosome 1p 36, a region where loss of heterozygosity (LOH) is frequently observed in primary human tumors. Allelic loss studies involving the 1p arm in breast carcinomas offer rates ranging from 13% to 75%, depending on the genetic interval being studied. We investigated LOH in an intragenic microsatellite marker, and those centromerically flanking the p73 gene, at 1p 36, and their correlations with patient age and 10 pathologic parameters in a series of 193 breast carcinomas. The LOH analysis was performed by amplifying DNA by PCR, using the five markers of the 1p 36 region (p73P1, D1S2694, D1S214, D1S2666 and D1S450). LOH was found in at least one of these markers in 27% of tumors. When we established the comparison between tumors with and without LOH and the distribution of the 10 pathologic parameters considered, we observed statistically significant differences in association with higher histologic grade (p = 0.02), more advanced pathological stage (p = 0.02), peritumoral vessel involvement (p = 0.04) and poorly differentiated carcinomas (p = 0.01), as well as in tumors that concomitantly exhibited lymph node metastases, peritumoral vessel involvement and absence of steroid receptors (p = 0.02). These data suggest that LOH in the p73 region could be pathogenically related to breast cancer and possibly to a poor tumor prognosis.

Microsatellite alterations and TP53 mutations in plasma DNA of small-cell lung cancer patients: follow-up study and prognostic significance

BACKGROUND

Small-cell lung cancer (SCLC), one of the major types of lung cancer, is associated with many different somatic molecular genetic changes. These alterations, observed in tumor DNA, have also been identified in the plasma DNA of patients. We undertook the present study to make a prospective investigation into the correlation between abnormal plasma DNA and patient survival.

PATIENTS AND METHODS

Thirty-five patients with SCLC were selected after histological diagnosis. Polymorphic markers (ACTBP2, UT762 and AR) were chosen for their reported high rate of alterations in SCLC and analyzed in tumor tissue, normal blood cells and plasma DNA. Furthermore, we looked for mutations of the TP53 gene in tumor and plasma DNA.

RESULTS

In 25 patients (71%) at least one molecular change precisely matching that of the primary tumor was detected in the plasma DNA. No difference in survival was observed between patients with aberrant plasma DNA and patients without plasma DNA alterations. However, patients with microsatellite modifications and TP53 mutations concomitantly, showed a significant difference (P = 0.02) in survival compared with patients bearing only one of these molecular changes. In 15 cases it was possible to find a correlation either between tumor response and disappearance of abnormal plasma DNA, or tumor progression and persistence of plasma DNA alterations.

CONCLUSIONS

Free plasma DNA with molecular alterations is present to a high degree in plasma DNA of SCLC patients and may have a role as a prognostic factor.

Nanometer-scale resolution of strain and interdiffusion in self-assembled InAs/GaAs quantum dots

Tomographic nanometer-scale images of self-assembled InAs/GaAs quantum dots have been obtained from surface-sensitive x-ray diffraction. Based on the three-dimensional intensity mapping of selected regions in reciprocal space, the method yields the shape of the dots along with the lattice parameter distribution and the vertical interdiffusion profile on a subnanometer scale. The material composition is found to vary continuously from GaAs at the base of the dot to InAs at the top.

An unusual form of persistent polyclonal B lymphocytosis in an infant

We report a case of persistent polyclonal lymphocytosis in an infant. The circulating lymphocytes were of a small to medium size and a small proportion were larger and had lymphoplasmacytoid features. The presence of either an infectious or mutagenic agent was excluded. The polyclonal B-cell nature of the lymphocyte was demonstrated by immunological markers and confirmed by Southern blot analysis and by polymerase chain reaction targeting immunoglobulin genes. In contrast to the common form of polyclonal lymphocytosis, this case was not associated with HLA-DR7 and/or abnormalities of chromosome 3, p53 or Bcl2/IgH. Whether this lymphocytosis represents a premalignant or a benign condition remains uncertain, although there has been no progression to date.

Atrial fibrillation after beating heart surgery

Postoperative atrial fibrillation (AF) is a frequent adverse event after coronary artery bypass grafting (CABG) and may negatively affect the early clinical outcome. We sought to investigate the risk factors, prevalence, and prognostic implications of postoperative AF in patients submitted to CABG without cardiopulmonary bypass (off-pump). The study population comprised 969 patients, 645 men (67%) and 324 women (33%) who had off-pump CABG at the Washington Hospital Center from January 1987 to May 1999. Preoperative AF patients were excluded (n = 15). Two hundred six patients (age 69 +/- 10 years, 137 men [66%]) developed AF, whereas 763 patients (age 61 +/- 12 years, 508 men [67%]) did not. Predictors of AF included age >75 years (odds ratio [OR] 3.0, 95% confidence interval [CI] 1.9 to 4.5; p <0.001), history of stroke (OR 2.1, CI 1.2 to 3.7; p = 0. 007), postoperative pleural effusion requiring thoracentesis (OR 3.2, CI 1.0 to 9.4; p = 0.03), and postoperative pulmonary edema (OR 5.1, CI 1.2 to 21; p = 0.02). Minimally invasive direct CABG was associated with a lower incidence of AF (OR 0.4, CI 0.3 to 0.7; p <0. 001). AF was associated with a prolonged postoperative hospital stay (9 +/- 6 days AF vs 6 +/- 5 days no AF, p <0.001). In-hospital mortality was significantly higher in AF patients (3% AF vs 1% no AF, p = 0.009). Patients with persistent AF had a higher postoperative in-hospital stroke rate than patients without persistent AF (9% vs 0. 6%, p <0.001). AF after beating heart surgery is associated with a higher in-hospital morbidity, mortality, and prolonged hospital stay. A minimally invasive surgical approach (minimally invasive direct CABG) is associated with a lower risk of AF.

Size-specific defensive structures in a horned weevil confirm a classic battle plan: avoid fights with larger opponents

A rigid sheath that extends deep into the prothorax of male Parisoschoenus expositus serves to receive the horns of opponents in battles over females. The male cannot use his own horn unless he receives his opponent's horn in his sheath. The length of a male's sheath is always approximately equal to the length of his own horns, so his body design is appropriate only for horn-locking battles with males whose horns are equal to or shorter than his own. Horn length and sheath length are dimorphic with respect to each other and to an indicator of body size. The switch points between morphs are very nearly the same for several relationships, so the different aspects of fighting morphology are tightly coordinated.

Beating heart versus conventional single-vessel reoperative coronary artery bypass

BACKGROUND

Reoperative (redo) coronary artery bypass grafting (CABG) with cardiopulmonary bypass (on-pump) is associated with a higher morbidity and mortality than first-time CABG. It is unknown, however, whether CABG without cardiopulmonary bypass (off-pump) may yield an improved clinical outcome over conventional on-pump redo CABG.

METHODS

We compared the perioperative outcomes of patients with single-vessel disease who underwent on-pump (n = 41) versus off-pump (n = 91) redo CABG between April 1992 and July 1999. The two groups were similar with respect to baseline characteristics and risk stratification: mean Parsonnet scores were 26 +/- 9 for on-pump versus 24 +/- 8 for off-pump patients (p = nonsignificant).

RESULTS

On-pump redo patients had a higher rate of postoperative transfusions (58% on-pump versus 27% off-pump, p = 0.001), prolonged ventilatory support (17% on-pump versus 4% off-pump, p = 0.03), and a higher rate of postoperative atrial fibrillation (29% on-pump versus 14% off-pump, p = 0.04). On-pump redo CABG was also associated with prolonged postoperative length of stay (8 +/- 4 days on-pump versus 5 +/- 2 days off-pump, p < 0.001). In-hospital mortality was significantly higher in on-pump than in off-pump patients (10% versus 1%, p = 0.03).

CONCLUSIONS

Single-vessel off-pump redo CABG can be performed safely with a lower operative morbidity and mortality than on-pump CABG and an abbreviated hospital stay compared with conventional on-pump redo CABG.