Associations of Abnormal Maternal Glucose Regulation in Pregnancy with Offspring Adiposity, Insulin Resistance, and Adipokine Markers During Childhood and Adolescence.

OBJECTIVE: To examine the associations of abnormal maternal glucose regulation in pregnancy with offspring adiposity, insulin resistance, adipokine, and inflammatory markers during childhood and adolescence. STUDY DESIGN: Project Viva is a prospective prebirth cohort (n = 2128 live births) initiated from 1999 through 2002 in Eastern Massachusetts, US. During the second trimester of pregnancy, clinicians used 2-step oral glucose challenge testing to screen for gestational diabetes mellitus. In the offspring, we measured anthropometry, insulin resistance, adipokines, lipids, and inflammatory markers in mid-childhood (n = 1107), early adolescence (n = 1027), and mid-adolescence (n = 693). We used multivariable linear regression models and generalized estimating equations adjusted for child age and sex, and for maternal age, race/ethnicity, education, parity, and smoking during pregnancy; we further adjusted for prepregnancy body mass index (BMI). RESULTS: In mid-adolescence (17.1 [0.8] years of age), offspring of mothers with gestational diabetes mellitus (n = 27) had a higher BMI z-score (ß; 95% Cl; 0.41 SD; 0.00, 0.82), sum of skinfolds (8.15 mm; 2.48, 13.82), homeostatic model assessment for insulin resistance (0.81 units; 0.13, 1.50), leptin z-score (0.40 SD; 0.01, 0.78), and leptin/adiponectin ratio z-score (0.51 SD; CI 0.09, 0.93) compared with offspring of mothers with normoglycemia (multivariable-adjusted models). The associations with BMI, homeostatic model assessment for insulin resistance, and adiponectin seemed stronger in mid-adolescence compared with earlier time points. The associations were attenuated toward the null after adjustment for maternal prepregnancy BMI. CONCLUSION: Exposure to gestational diabetes mellitus is associated with higher adiposity, insulin resistance, and altered adipokines in mid-adolescence. Our findings suggest that the peripubertal period could be a key time for the emergence of prenatally programmed metabolic abnormalities.

Evaluation of Lead-In Direct Oral Anticoagulant Prescribing Practices in Newly Diagnosed Venous Thromboembolism.

Various lead-in dosing strategies have been used in clinical practice for venous thromboembolism (VTE), and guidelines do not currently address if the full lead-in dosing duration is necessary after receiving parenteral anticoagulation. This study aims to identify whether full lead-in dosing duration surrounding parenteral anticoagulation affects thrombotic and bleeding outcomes. A single-center, retrospective cohort study was conducted of hospitalized patients diagnosed with VTE and treated with apixaban or rivaroxaban. Patients were grouped depending on duration of lead-in dosing, with the full lead-in dosing group considered as the appropriate duration of the direct oral anticoagulant. The primary outcome was the recurrence of VTE within the index admission to 6 months. Secondary outcomes included major bleeding, clinically relevant minor bleeding, and mortality. Ninety-three patients were prescribed full lead-in dosing, while 99 patients received reduced lead-in dosing. The primary outcome of recurrent VTE was similar between the reduced lead-in group compared to the full lead-in group (3% vs 2%; P = 1.0). Major bleeding within the index admission was significantly higher in the reduced lead-in group: 11 versus 2 (P = .02). There were no significant differences in other secondary outcomes. Full lead-in dosing compared to reduced lead-in dosing duration for VTE had similar rates of thrombotic and mortality events. The higher rate of major bleeding in the reduced lead-in dosing group likely reflects the prescribing practices in less stable patients. This study provides evidence to support reduced lead-in dosing duration in high-risk patients without compromising efficacy outcomes.

Benzylic Trifluoromethyl Accelerates 1,6-Elimination Toward Rapid Probe Activation.

Activity-based detection of hydrogen sulfide in live cells can expand our understanding of its reactivity and complex physiological effects. We have discovered a highly efficient method for fluorescent probe activation, which is driven by H2S-triggered 1,6-elimination of an α-CF3-benzyl to release resorufin. In detecting intracellular H2S, 4-azido-(α-CF3)-benzyl resorufin offers significantly faster signal generation and improved sensitivity compared to 4-azidobenzyl resorufin. Computed free energy profiles for the 1,6-elimination process support the hypothesis that a benzylic CF3 group can reduce the activation energy barrier toward probe activation. This novel probe design allows for near-real-time detection of H2S in HeLa cells under stimulation conditions.

Determinants of Clinical Decision Making under Uncertainty in Dentistry: A Scoping Review.

Clinical decision-making for diagnosing and treating oral and dental diseases consolidates multiple sources of complex information, yet individual clinical judgements are often made intuitively on limited heuristics to simplify decision making, which may lead to errors harmful to patients. This study aimed at systematically evaluating dental practitioners' clinical decision-making processes during diagnosis and treatment planning under uncertainty. A scoping review was chosen as the optimal study design due to the heterogeneity and complexity of the topic. Key terms and a search strategy were defined, and the articles published in the repository of the National Library of Medicine (MEDLINE/PubMed) were searched, selected, and analysed in accordance with PRISMA-ScR guidelines. Of the 478 studies returned, 64 relevant articles were included in the qualitative synthesis. Studies that were included were based in 27 countries, with the majority from the UK and USA. Articles were dated from 1991 to 2022, with all being observational studies except four, which were experimental studies. Six major recurring themes were identified: clinical factors, clinical experience, patient preferences and perceptions, heuristics and biases, artificial intelligence and informatics, and existing guidelines. These results suggest that inconsistency in treatment recommendations is a real possibility and despite great advancements in dental science, evidence-based practice is but one of a multitude of complex determinants driving clinical decision making in dentistry. In conclusion, clinical decisions, particularly those made individually by a dental practitioner, are potentially prone to sub-optimal treatment and poorer patient outcomes.

Investigating the Roles of Active Site Residues in Mycobacterium tuberculosis Indole-3-glycerol Phosphate Synthase, a Potential Target for Antitubercular Agents.

Mycobacterium tuberculosis drug resistance is emerging and new drug targets are needed. Tryptophan biosynthesis is necessary for M. tuberculosis replication and virulence. Indole-3-glycerol phosphate synthase (IGPS) catalyzes a step in M. tuberculosis tryptophan biosynthesis and has been suggested as a potential anti-infective target, but our understanding of this enzyme is limited. To aid in inhibitor design and gain a greater mechanistic picture of this enzyme, there is a need to understand the roles of active site amino acids in ligand binding and catalysis. In this work, we explored the roles of conserved active site amino acids Glu57, Lys59, Lys119, Glu168, and Glu219. Mutation of each to Ala results in loss of all detectable activity. The Glu57Gln, Lys59Arg, Lys119Arg, Glu168Gln, and Glu219Asp mutations result in large activity losses, while Glu219Gln has enhanced activity. Analysis of the enzymatic data yields the following main conclusions: (A) Lys119 is the likely catalytic acid in the CdRP ring closure step. (B) Glu168 stabilizes a charged reaction intermediate and may also be the catalytic base. (C) Glu57, Glu219, and Lys119 form a closely arranged triad in which Glu57 and Glu219 modulate the pKa of Lys119, and thus overall activity. This increased understanding of inter- and intramolecular interactions and demonstration of the highly coordinated nature of the M. tuberculosis IGPS active site provide new mechanistic information and guidance for future work with this potential new drug target.

A prospective multicenter evaluation of a new side-port endoscopic ultrasound-fine-needle aspiration in solid upper gastrointestinal lesions.

BACKGROUND AND STUDY AIMS: Diagnostic yield of endoscopic ultrasound (EUS)-fine-needle aspiration (FNA) varies depending on the equipment used and the site targeted. Multiple needle passes are usually required to obtain a diagnosis. A new needle incorporating a side-port carries a theoretical advantage regarding acquisition of cytological material. The aim of the study was to demonstrate the safety and efficacy of the Olympus side-port needle in solid upper gastrointestinal indications. PATIENTS AND METHODS: A prospective multicenter evaluation of patients referred for EUS-FNA for solid lesions was performed across six tertiary gastroenterology referral centers in four capital cities in Australia. The main outcome measures include cytological diagnosis, number of needle passes required for diagnosis and complication rates. RESULTS: Thirty patients (17 men; 13 women) with a mean age of 67.5 years were studied. Indications included pancreatic or biliary mass in 24 patients, retroperitoneal or periduodenal mass in 2, enlarged lymph node in 2, a gastric submucosal tumor in 1 and a subcarinal mass in 1. The mean size of the lesions was 3.47 cm (range, 0.5-8 cm). All but one case had a diagnosis made (96.7%). The mean number of passes required to reach a diagnosis was 1.7. In neoplastic lesions the diagnosis was made with a mean of 1.6 passes. No complications were encountered. CONCLUSIONS: The new EUS-FNA needle with side port appears effective and safe in solid upper gastrointestinal EUS-FNA indications.

'Short' double-balloon enteroscope endoscopic retrograde cholangiopancreatography in patients with a surgically altered upper gastrointestinal tract.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) remains a challenge for endoscopists in patients with surgically altered anatomy of the upper gastrointestinal tract. Double-balloon enteroscopes (DBEs) have revolutionized the ability to access the small bowel. The indication for its therapeutic use is expanding to include ERCP for patients who have undergone small bowel reconstruction. Most of the published experiences in DBE-assisted ERCP have used conventional double-balloon enteroscopes that are 200 cm in length, which do not permit use of the standard ERCP accessories. The authors report their experience with DBE-assisted ERCP using a 'short' DBE in patients with surgically altered anatomy. METHODS: A retrospective review of patients with previous small bowel reconstruction who underwent ERCP with a 'short' DBE at the Centre for Therapeutic Endoscopy and Endoscopic Oncology (Toronto, Ontario) between February 2007 and November 2008 was performed. RESULTS: A total of 20 patients (10 men) with a mean age of 57.9 years (range 26 to 85 years) underwent 29 sessions of ERCP with a DBE. Six patients underwent Billroth II gastroenterostomy, seven patients Roux-en-Y hepaticojejunostomy, five patients Roux-en-Y gastrojejunostomy, one patient Roux-en-Y esophagojejunostomy and one patient a Whipple's operation with choledochojejunostomy. Some patients (n=12 [60%]) underwent previous attempts at ERCP in which the papilla of Vater or bilioenteric anastomosis could not be reached with either a duodenoscope or pediatric colonoscope. All procedures were performed with a commercially available DBE (working length 152 cm, distal end diameter 9.4 mm, channel diameter 2.8 mm). The procedures were performed under conscious sedation with intravenous midazolam, fentanyl and diazepam, except in one patient in whom general anesthesia was administered. Either the papilla of Vater or bilioenteric anastomosis was reached in 25 of 29 cases (86.2%) in a mean duration of 20.8 min (range 5 min to 82 min). Bile duct cannulation was successful in 24 of 25 cases in which the papilla or bilioenteric anastomosis was reached. Therapeutic interventions were successful in 15 patients (24 procedures) including sphincterotomy (n=7), stone extraction (n=9), biliary dilation (n=8), stent placement (n=9) and stent removal (n=8). The mean total duration of the procedures was 70.7 min (range 30 min to 117 min). There were no procedure-related complications. CONCLUSION: DBEs enable successful diagnostic and therapeutic ERCP in patients with a surgically altered anatomy of the upper gastrointestinal tract. It is a safe, feasible and less invasive therapeutic option in this group of patients. Standard 'long' DBEs have limitations of long working length and the need for modified ERCP accessories. 'Short' DBEs are equally as effective in reaching the target limb as standard 'long' DBEs, and overcomes some limitations of long DBEs to result in high success rates for endoscopic therapy.

One hundred and seventy-eight consecutive pancreatoduodenectomies without mortality: role of the multidisciplinary approach.

BACKGROUND: Pancreatoduodenectomy offers the only chance of cure for patients with periampullary cancers. This, however, is a major undertaking in most patients and is associated with a significant morbidity and mortality. A multidisciplinary approach to the workup and follow-up of patients undergoing pancreatoduodenectomy was initiated at our institution to improve the diagnosis, resection rate, mortality and morbidity. We undertook the study to assess the effect of this approach on diagnosis, resection rates and short-term outcomes such as morbidity and mortality. METHODS: A prospective database of patients presenting with periampullary cancers to a single surgeon between April 2004 and April 2010 was reviewed. All cases were discussed at a multidisciplinary meeting comprising surgeons, gastroenterologists, radiologists, oncologists, radiation oncologists, pathologists and nursing staff. A standardized investigation and management algorithm was followed. Complications were graded according to the Clavien-Dindo classification. RESULTS: A total of 295 patients with a periampullary lesion were discussed and 178 underwent pancreatoduodenectomy (resection rate 60%). Sixty-one patients (34%) required either a vascular or an additional organ resection. Eighty-nine patients experienced complications, of which the commonest was blood transfusion (12%). Thirty-four patients (19%) had major complications, i.e. grade 3 or above. There was no in-hospital, 30-day or 60-day mortality. CONCLUSIONS: Pancreatoduodenectomy can safely be performed in high-volume centers with very low mortality. The surgeon's role should be careful patient selection, intensive preoperative investigations, use of a team approach, and an unbiased discussion at a multidisciplinary meeting to optimize the outcome in these patients.

Regional variations in public opinion on the affordable care act.

One year after passage, the Patient Protection and Affordable Care Act (ACA) remains a divisive topic. Most publicly released polls on the law have focused on the views of Americans as a whole. But with much of the responsibility of implementation lying with the states, this essay explores whether opinion differs geographically. The analysis finds that views on the health reform law do differ by region, and these differences are most likely driven by the political leanings of a given area. While opinion nationally differs by age and race, this pattern does not hold when looking by region. Areas that have a larger share of uninsured and are slated to receive greater federal funding under the ACA also do not differ in their opinions. These data suggest that regional variations in attitudes about the ACA are based less on the demographic structure of a region and more on the political ideologies of residents in a given region. As implementation of the law continues, this analysis shows that national opinion data mask important regional variations in views of the ACA.

Endoscopic cryotherapy for the management of gastric antral vascular ectasia.

BACKGROUND: Gastric antral vascular ectasia (GAVE) is an uncommon but clinically significant cause of chronic GI bleeding. OBJECTIVE: To assess the efficacy and safety of cryotherapy for endoscopic treatment of GAVE. DESIGN: Patients received 3 sessions of endoscopic cryotherapy at 3-week to 6-week intervals and had a follow-up endoscopy 4 weeks thereafter. They were followed prospectively in terms of clinical and endoscopic response. SETTING: Tertiary-care center, between October 2004 and April 2006. PATIENTS: The patients were 43 to 89 years of age, with a diagnosis of GAVE and documented iron deficiency anemia. Eight patients had a history of overt GI bleeding. Eight patients (67%) had previously been treated with argon plasma coagulation (APC) (median 6 sessions, range 1-10 sessions) and failed to respond or had a recurrence. RESULTS: Twelve patients were enrolled. Six patients (50%) had a complete response, and 6 patients had a partial response. The mean number of units of blood transfused in the period of 3 months before cryotherapy and during the period of follow-up of 3 months was 4.6 and 1.7 units, respectively. An increased mean Hb level, from 9.9 to 11.3 g/dL, was noted. The average duration of the cryotherapy was 5 minutes (range 1-15 minutes). In 32 of 36 cryotherapy treatment sessions performed (89%), it was technically possible to treat more than 90% of GAVE lesions. There were no immediate cryotherapy-related complications, and none of the patients required admission after the procedure. LIMITATIONS: A pilot study from a single center. CONCLUSIONS: Endoscopic cryotherapy is a safe and effective treatment for GAVE. It appears to be effective, even for GAVE refractory to APC therapy. Optimal cryogen, delivery device, and treatment protocols are yet to be determined.

Double-balloon enteroscopy following capsule endoscopy in the management of obscure gastrointestinal bleeding: outcome of a combined approach.

BACKGROUND: There is no consensus on the relative accuracy of capsule endoscopy (CE) versus double-balloon enteroscopy (DBE) to investigate obscure gastrointestinal bleeding (GIB). CE is less invasive, but DBE more directly examines the small bowel, and allows tissue sampling plus therapeutic intervention. OBJECTIVES: To evaluate the yield and outcome of DBE following CE in patients with obscure GIB. METHODS: After DBE became readily available at the Centre for Therapeutic Endoscopy and Endoscopic Oncology (St Michael's Hospital, Toronto, Ontario), all patients with obscure GIB seen from December 2002 to June 2007 were evaluated identically, first with CE, then with DBE (some with further interventions). Findings, adverse outcomes and interventions are reported. RESULTS: Fifty-one patients (25 women) with a mean (range) age of 64.1 years (34 to 83 years) are reported. Eight patients underwent DBE twice, for a total of 59 DBEs. Fourteen patients had overt GIB and the median (range) number of red blood cell unit transfusions was 10 (0 to 100). The positive findings for each type of lesion were compared in these 51 patients: angiodysplasia (CE 64.7% and DBE 61%, P=0.3), ulcers (CE 19.6% and DBE 18.6%, P=0.5), bleeding lesions (CE 43.1% and DBE 15.3%, P=0.0004) and mass (CE 10.2% and DBE 8.5%, P=0.5). DBE provided the advantage of therapeutic intervention: argon plasma coagulation (33 of 59 DBEs), clipping (two of 59), both argon plasma coagulation and clipping (three of 59), polypectomy (two of 59), tattooing (52 of 59) and biopsies (11 of 59). DBE detected lesions not seen by CE in 21 patients; lesions were treated in 18 patients. However, CE detected 31 lesions not seen by DBE. No major complications occurred with either examination. CONCLUSION: Overall detection rates for both techniques are similar. Each technique detected lesions not seen by the other. These data suggest that CE and DBE are complementary and that both evaluate obscure GIB more fully than either modality alone.

Assessment of plasma DNA levels, allelic imbalance, and CA 125 as diagnostic tests for cancer.

BACKGROUND: Allelic imbalance (AI), the loss or gain of chromosomal regions, is found in many cancers. AI can be detected in genomic tumor DNA released into the blood after necrosis or apoptosis. We evaluated plasma DNA concentration, allelic status in plasma DNA, and serum CA 125 level as screening tests for ovarian and other cancers. METHODS: Plasma samples were obtained from 330 women (44 normal healthy control individuals, 122 patients with various cancers, and 164 control patients with non-neoplastic diseases). Plasma DNA concentration was determined in all samples. Allelic status was determined by digital single nucleotide polymorphism (SNP) analysis with eight SNP markers in plasma DNA from 54 patients with ovarian cancer and 31 control patients. CA 125 was determined in 63 samples. Receiver-operating characteristic (ROC) curves were plotted, and the areas under the ROC curves--a measure of the overall ability of a diagnostic test with multiple cutoffs to distinguish between diseased and nondiseased individuals--were determined. RESULTS: The area under the ROC curve for plasma DNA concentration was 0.90 for patients with neoplastic disease versus healthy control individuals and 0.74 for patients with neoplastic diseases versus control patients with non-neoplastic diseases. For control subjects given a specificity of 100% (95% confidence interval [CI] = 92% to 100%), the highest sensitivity achieved was 57% (95% CI = 49% to 67%). AI in at least one SNP was found in 87% (95% CI = 60% to 98%) of patients with stage I/II ovarian cancer and 95% (95% CI = 83% to 99%) of patients with stage III/IV ovarian cancer, but AI was not found in 31 patients with non-neoplastic diseases (specificity = 100%, 95% CI = 89% to 100%). The area under the ROC curve assessing AI was 0.95. Combining the serum CA 125 level with the plasma DNA concentration increased the area under the ROC curve from 0.78 (CA 125 alone) to 0.84. CONCLUSION: Plasma DNA concentration may not be sensitive or specific enough for cancer screening or diagnosis, even when combined with CA 125. AI was detected with high specificity in plasma DNA from patients with ovarian cancer and should be studied further as a screening tool.

In vitro generation of lymphocytes from embryonic stem cells.

Lymphocytes arise during ontogeny via a series of increasingly restricted intermediates. Initially, the mesoderm gives rise to hemangioblasts, which can differentiate into endothelial precursors, or hematopoietic stem cells (HSCs). HSCs can either self-renew or differentiate into lineage-restricted progenitors and, ultimately, to mature effector cells. This complex process is only beginning to be understood, and the ability to generate lymphocytes from embryonic stem (ES) cells in vitro will facilitate further study by providing a model system in which the effects of genetic and environmental manipulations of ES-cell-derived progenitors can be examined. In this protocol, we describe procedures for generating either B- and NK- or T-lymphocytes from mouse ES cells in vitro.

Detection of allelic imbalance in ascitic supernatant by digital single nucleotide polymorphism analysis.

PURPOSE: Cytological examination of ascitic fluid is critical for clinical management of patients with peritoneal or pelvic diseases. Such morphological examination can only achieve a sensitivity of <62%, and thus a molecular test that is able to distinguish benign versus malignant ascites could be clinically useful. In this study we determined the presence of allelic imbalance (AI) in tumor-released DNA in ascitic supernatant by directly counting the alleles using a newly developed technology, digital single nucleotide polymorphism (SNP) analysis. EXPERIMENTAL DESIGN: Allelic status was assessed using a total of seven SNP markers that commonly demonstrated AI in ovarian, colorectal, and pancreatic cancers. RESULTS: With digital SNP analysis, AI in at least one SNP marker was found in 19 of 20 (95%) ascitic fluid DNA samples obtained from patients with cytologically proven carcinomas in ascitic fluid. In contrast, AI was detected in only 1 of 20 patients with negative cytology. This latter patient with AI in her ascites had known stage III ovarian carcinoma at the time of cytology sampling. The ascitic specimen of this patient demonstrated the presence of carcinoma cells in culture with an identical AI pattern found in the ascitic supernatant and surgical specimen. CONCLUSIONS: These findings suggest that detection of AI using digital SNP analysis can be a useful adjunct for the detection of ovarian and other types of cancer in ascitic fluid.

Development of lymphoid lineages from embryonic stem cells in vitro.

Lymphocyte development proceeds through highly ordered and regulated stages, as multipotent hematopoietic progenitors differentiate into lineage-defined progenitors, and ultimately into mature effector cells. The ability to generate lymphocytes from embryonic stem (ES) cells in vitro should facilitate the study of these complex differentiation steps by providing a model system in which the effects of genetic and nongenetic manipulations can be examined in a controlled setting. These advances may also contribute to future therapeutic approaches. In this article, we describe the procedure for generating functional lymphocytes from mouse ES cells.

Diffuse reflectance spectroscopy in Barrett's esophagus: developing a large field-of-view screening method discriminating dysplasia from metaplasia.

We evaluated diffuse reflectance spectroscopy implemented as a small field-of-view technique for discrimination of dysplasia from metaplasia in Barrett's esophagus as an adjuvant to autofluorescence endoscopy. Using linear discriminant analysis on 2579 spectra measured in 54 patients identified an optimum a 4-wavelength classifier (at 485, 513, 598 and 629 nm). Sensitivity and specificity for a test data set were 0.67 and 0.85, respectively. Spectroscopic results show that this technique could be implemented in wide-field imaging mode to improve the accuracy of existing endoscopy techniques for finding early pre-malignant lesions in Barrett's esophagus. Results show that the discrimination occurs likely due to redistribution of blood content in the tissue sensed by the optical probing with the wavelength-dependent sampling depth.

Describing intimate partner stalking over time: an effort to inform victim-centered service provision.

Stalking has increasingly been the subject of legislation and research in the past 20 years. Within intimate partner violence, the context where it is most likely to occur, stalking predicts both greater danger and greater distress for the victim. However, research shows that practitioners are often unsure how to address stalking, and that the remedies available may not be effective. This longitudinal exploration of stalking focused on the experience of victims of intimate partner stalking and was conducted by Safe Horizon, an organization providing assistance to victims of violence and abuse in New York City. The sample of 82 women was interviewed monthly over 7 months, and the data were analyzed using growth curve models. We found that stalking decreased over time at a marginally significant level, and that change in stalking varied among participants. Perceived safety followed a similar pattern, increasing but not significantly, while stalking-related distress decreased significantly. The slopes of these variables were correlated, such that as stalking frequency decreased, perceived safety increased and distress decreased. Help-seeking was greater from court sources than victim services over the course of the study, but neither help source was related to a significant decrease in the stalking trajectory. According to victim report, orders of protection (OP) were helpful at some points and not at others. Implications of these results for offering victim-centered services are discussed.

In vitro generation of T lymphocytes from embryonic stem cell-derived prehematopoietic progenitors.

Embryonic stem (ES) cells can differentiate into most blood cells in vitro, providing a powerful model system to study hematopoiesis. However, ES cell-derived T lymphocytes have not been generated in vitro, and it was unresolved whether such potential is absent or merely difficult to isolate. Because the latter case might result from rapid commitment to non-T-cell fates, we isolated ES cell-derived prehematopoietic precursors for reconstitution of fetal thymic organ cultures. We found a transient Flk1+CD45- subset of these precursors generated T lymphocytes in vitro, and the use of reaggregate thymic organ cultures greatly enhanced reconstitution frequency. These findings reveal that ES cells can exhibit in vitro T-cell potential, but this is restricted to early stages of ES cell differentiation. Moreover, the results support the notion that the thymic microenvironment can induce T-cell differentiation from a subset of prehematopoietic progenitors and suggest deficient migration into intact thymi hindered previous attempts to generate T cells in vitro from ES cell-derived progenitors. These findings demonstrate that a defined subset of ES cells has the potential to generate T cells in vitro and could contribute to greater understanding of the molecular events of hematopoietic induction and T-cell lineage commitment.

Diverse tumorigenic pathways in ovarian serous carcinoma.

This study was undertaken to analyze genetic alterations in 108 sporadic serous ovarian neoplasms to elucidate ovarian serous carcinogenesis. Our results demonstrate that K-ras mutations occur in approximately 50% of serous borderline tumors (SBTs), non-invasive micropapillary serous carcinomas (MPSCs), and invasive micropapillary serous carcinomas, which represent a morphological continuum of tumor progression. Moreover, progressive increase in the degree of allelic imbalance of chromosomes 1p, 5q, 8p, 18q, 22q, and Xp was observed comparing serous borderline tumors to noninvasive and invasive micropapillary serous carcinomas. In contrast, high-grade (conventional serous carcinoma) tumors contained wild-type K-ras in all 23 cases studied and a high frequency of allelic imbalance even in small (early) primary tumors similar to that found in advanced stage tumors. Based on these findings, we propose a dualistic model for ovarian serous carcinogenesis. One pathway involves a stepwise progression from SBT to noninvasive and then invasive MPSC. The other pathway is characterized by rapid progression from the ovarian surface epithelium or inclusion cysts to a conventional (high-grade) serous carcinoma.