Household income is associated with functional outcomes in a multi-institutional cohort of patients with ischemic stroke and COVID-19

OBJECTIVES

The COVID-19 pandemic has heightened awareness of health disparities associated with socioeconomic status (SES) across the United States. We examined whether household income is associated with functional outcomes after stroke and COVID-19.

MATERIALS AND METHODS

This was a multi-institutional, retrospective cohort study of consecutively hospitalized patients with SARS-CoV-2 and radiographically confirmed stroke presenting from March through November 2020 to any of five comprehensive stroke centers in metropolitan Chicago, Illinois, USA. Zip-code-derived household income was dichotomized at the Chicago median. Logistic regression was used to examine the relationship between household income and good functional outcome (modified Rankin Scale 0-3 at discharge, after ischemic stroke).

RESULTS

Across five hospitals, 159 patients were included. Black patients comprised 48.1%, White patients 38.6%, and Hispanic patients 27.7%. Median household income was $46,938 [IQR: $32,460-63,219]. Ischemic stroke occurred in 115 (72.3%) patients (median NIHSS 7, IQR: 0.5-18.5) and hemorrhagic stroke in 37 (23.7%). When controlling for age, sex, severe COVID-19, and NIHSS, patients with ischemic stroke and household income above the Chicago median were more likely to have a good functional outcome at discharge (OR 7.53, 95% CI 1.61 - 45.73; P=0.016). Race/ethnicity were not included in final adjusted models given collinearity with income.

CONCLUSIONS

In this multi-institutional study of hospitalized patients with stroke, those residing in higher SES zip codes were more likely to have better functional outcomes, despite controlling for stroke severity and COVID-19 severity. This suggests that area-based SES factors may play a role in outcomes from stroke and COVID-19.

Impact of COVID-19 on neurocritical care delivery and outcomes in patients with severe acute brain injury - Assessing the initial response in the first US epicenter

To investigate the pandemic’s impact on critically ill patients with neurological emergencies, we compared care metrics and outcomes of patients with severe acute brain injury (SABI) before and during the initial COVID-19 surge at our institution. We included adult patients with SABI during two separate three-month time periods: 'pre-COVID vs COVID'. We further stratified the COVID cohort to characterize outcomes in patients requiring COVID-19 precautions (Patient Under Investigation, ‘PUI’). The primary endpoint was in-hospital mortality; secondary endpoints included length of stay (LOS), diagnostic studies performed, time to emergent decompressive craniectomies (DCHC), ventilator management, and end-of-life care. We included 394 patients and found the overall number of admissions for SABI declined by 29 % during COVID (pre-COVID n = 231 vs COVID, n = 163). Our primary outcome of mortality and most secondary outcomes were similar between study periods. There were more frequent extubation attempts (72.1 % vs 76 %) and the mean time to extubation was shorter during COVID (55.5 h vs 38.2 h). The ICU LOS (6.10 days vs 4.69 days) and hospital LOS (15.32 days vs 11.74 days) was shorter during COVID. More PUIs died than non-PUIs (51.7 % vs 11.2 %), but when adjusted for markers of illness severity, this was not significant. We demonstrate the ability to maintain a consistent care delivery for patients with SABI during the pandemic at our institution. PUIs represent a population with higher illness severity at risk for delays in care. Multicenter, longitudinal studies are needed to explore the impact of the pandemic on patients with acute neurological emergencies.

Tunable light absorption of graphene using topological interface states

A tunable light absorption of graphene using topological interface states (TISs) is presented. The monolayer graphene is embedded in the interface of asymmetric topological photonic crystals (ATPCs). A strong absorption phenomenon occurs by the excitation of TISs. It is found that the absorption spectra are intensively dependent on the chemical potential of graphene and the periodic number of the ATPCs. Furthermore, the absorption can be rapidly switched in a slight variation of chemical potential, which is modulated by the applied gate voltage on graphene. This study not only opens up a new approach for enhancing light-monolayer graphene interactions, but also provides for practical applications in high absorption optoelectronic devices. This strong absorption phenomenon is different from those in Fabry-Perot resonators, nano-cavities photonic crystal, and traditional topological photonic crystals (TPCs).

Enrollment of research subjects through telemedicine networks in a multicenter acute intracerebral hemorrhage clinical trial: design and methods

BACKGROUND

Enrollment of subjects in acute stroke trials is often hindered by narrow timeframes, because a large proportion of patients arrive via transfers from outside facilities rather than primary arrival at the enrolling hospital.

RATIONALE

Telemedicine networks have been increasingly used for provision of care for acute stroke patients at facilities outside of major academic centers. Treatment decisions made through telemedicine networks in patients with acute ischemic stroke have been shown to be safe, reliable, and effective. With the expanding use of this technology and the impediments to enrolling subjects into clinical trials, this approach can be applied successfully to the field of clinical research.

METHODS AND CONCLUSIONS

The Antihypertensive Treatment of Acute Cerebral Hemorrhage II trial is a phase III randomized multicenter trial that has developed a protocol in collaboration with participating sites to implement the use of telemedicine networks for the enrollment of research subjects. The protocol describes the operating procedures and legal and Institutional Review Board perspectives for its implementation.

Abstract W MP28: Early Elevation of Plasma Soluble Fms-Like Tyrosine Kinase-1 is Associated With Poor Functional Outcome After Subarachnoid Hemorrhage

Background: Vasospasm (VSP) and brain injury following subarachnoid hemorrhage (SAH) are associated with tissue hypoxia and vascular endothelial growth factor (VEGF) release. Soluble Fms-like tyrosine kinase-1 (sFlt-1), a truncated soluble form of VEGF receptor-1, is an endogenous VEGF inhibitor released in response to hypoxia and nitric oxide deficiency. SFlt-1 is anti-angiogenic and mediates endothelial dysfunction. We hypothesize sFlt-1 elevation may be associated with VSP and poor SAH outcome.

Methods: We prospectively enrolled consecutive SAH subjects, banked serial blood samples, and evaluated their modified Rankin scores (mRS) at 3 month intervals. Poor functional outcome was defined as mRS>2. Angiographic VSP was defined as >50% reduction in caliber of any vessel on post-SAH day 7 cerebral angiogram. In 63 SAH subjects, we compared plasma sFlt-1 by ELISA on post-SAH days 3 and 5 by VSP and outcome status using Wilcoxon rank sum or Student’s t-test depending on data distribution. Bonferroni correction was used for multiple comparisons. Logistic regression was used to adjust for confounders. Associations were measured using Pearson’s or Spearman’s correlation depending on data distribution.

Results: Twenty-seven subjects (43%) had poor 3-month outcome and 31 (49%) developed VSP. Elevated sFlt-1 level on post-SAH day 3 was associated with poor 3-month outcome (p=0.02) while post-SAH day 5 sFlt-1 level showed no association. SFlt-1 levels were not associated with Hunt and Hess (HH) or Fisher grades or with VSP. SFlt-1 was inversely correlated to VEGF (p=0.04, r=0.26). Post-SAH day 3 sFlt-1 level was independently associated with poor SAH outcome after adjustment for HH grade, age, and VEGF level (p=0.03). VEGF was not associated with VSP or SAH outcome.

Conclusion: Early elevation of plasma sFlt-1 on post-SAH day 3 is independently associated with poor 3-month SAH outcome after adjustment for clinical predictors of SAH outcome and for VEGF. Inverse correlation suggests possible negative feedback control between sFlt-1 and VEGF in SAH. Future studies are necessary to determine the source of sFlt-1 in SAH and its role in SAH-associated brain injury. Replication in a larger cohort is necessary to validate sFlt-1 as a potential biomarker for SAH outcome.

Abstract W MP29: CSF MicroRNA-181b is Associated With Poor 6-Month Outcome Following Subarachnoid Hemorrhage

Background: Early brain injury and vasospasm (VSP) in subarachnoid hemorrhage (SAH) are associated with inflammation and release of TNFα, which correlates with poor SAH clinical outcome. TNFα regulates the expression of microRNA (miR) 181b, which mediates NF-κB signaling and is known to exacerbate ischemic stroke in animal models. MiRs have higher stability in biological fluids than peptides and may be candidate clinical biomarkers. We hypothesize that miR-181b is present in SAH CSF and may be associated with SAH outcome.

Methods: We prospectively enrolled consecutive SAH subjects, banked serial CSF samples, and evaluated their modified Rankin scores (mRS) via telephone follow-up every 3 months. Poor functional outcome was defined as mRS>2. Angiographic VSP was defined as >50% reduction in caliber of any vessel on post-SAH day 7 cerebral angiogram. In 54 SAH subjects, we compared CSF miR-181b and 26a (as control) by quantitative PCR on post-SAH day 3 with respect to VSP and outcome using Student’s t-test after log-transformation of data with non-normal distribution. Associations were measured using Pearson’s or Spearman’s correlation depending on data distribution.

Results: Twenty-seven subjects (50%) developed VSP and 21 (39%) had poor 6-month outcome. MiRs-181b and 26a were consistently measurable in SAH CSF, and miR levels were not associated with Hunt and Hess or Fisher grades. Elevation of CSF miR-181b was associated with poor 6-month outcome in SAH (p=0.04). CSF miR-181b inversely correlated with blood TNFα (r=0.74, p=0.0001). CSF miR-181b was not associated with VSP. CSF miR-26a was not associated with VSP or with clinical outcome in SAH.

Conclusion: MiR-181b is present in human CSF after SAH and early elevation of CSF miR-181b is associated with poor 6-month outcome but not with VSP after SAH. Lack of association between control miR-26a and outcome suggests that association between miR-181b and SAH outcome is not due to a non-specific miR surge in more severe cases. Inverse correlation between blood TNFα and CSF miR-181b suggests TNFα may mediate miR-181b release into CSF. Future mechanistic studies on the role of miR-181b in SAH-related brain injury and validation studies in larger cohorts are necessary to understand the role of miR-181b as a SAH biomarker.

Abstract TP426: Candidate CSF Cytokine and Chemokine Biomarkers for Vasospasm and Poor Outcome in Human Subarachnoid Hemorrhage

Introduction: Growing evidence suggest inflammation plays a key role in the pathogenesis of vasospasm (VSP) and secondary ischemic injury following subarachnoid hemorrhage (SAH). While elevations of select pro-inflammatory cytokines such interleukin (IL) 6 in cerebrospinal fluid (CSF) are linked to VSP in SAH, it is unclear which cytokines are measurable in SAH CSF. We explore a panel of cytokines and chemokines during peak VSP time window in human SAH in search for novel CSF biomarkers.

Methods: CSF samples were collected through external ventricular drain from a prospective SAH cohort. Clinical outcome was evaluated at 3- and 6-months using modified Rankin scores (mRS). Poor outcome was defined as mRS>2. Angiographic VSP was defined as >50% reduction in caliber of any vessel on post-SAH day 7 cerebral angiogram. In 29 SAH subjects, we compared post-SAH day 5 CSF biomarker profile with respect to outcome and VSP using Milliplex panel (EMD Millipore) with 42 biomarkers. Continuous variables were compared using Wilcoxon rank sum test. Benjamin-Hochberg correction was used for multiple comparisons.

Results: VSP occurred in 45% of the SAH cohort, and 52% of this cohort had good outcome at 3 month. Of the 42 biomarkers, 39 were measurable in SAH CSF. Elevated CSF IL-4 showed strongest trend towards association with good outcome at 3-month (p=0.0049) and at 6-months (p=0.02). Other CSF biomarkers showing trend toward association with outcome include epidermal growth factor (p=0.035), fractalkine (p=0.045), and platelet-derived growth factor AA (p=0.024). Elevation of a different cluster of biomarkers showed trend towards association with VSP: IL-5 (p=0.041), IL-17A (p=0.049), and IL-2 (p=0.047). No single marker reached significance at p<0.05 level after adjustment for multiple comparisons.

Conclusions: Differential expression of cytokine and chemokines are present in CSF post SAH. Results from this small pilot study suggest a possible association between elevation of CSF anti-inflammatory cytokine IL-4 and good SAH outcome. This is consistent with animal studies showing IL-4 attenuates ischemic injury and promotes neuroprotection. Larger targeted studies are necessary to investigate the role of cytokines and specifically CSF IL-4 in SAH outcome.

Abstract WP304: Prothrombin Complex Concentrate Rapidly Reverses Coagulopathy but does not Alter Mortality in Warfarin Intracerebral Hemorrhage

INTRODUCTION: Warfarin-associated intracerebral hemorrhage (wICH) remains the most lethal form of iatrogenic stroke. Conventional therapy with fresh frozen plasma (FFP) and intravenous vitamin K takes up to 30 hrs to normalize the international normalized ratio (INR). Prothrombin complex concentrate (PCC) does not require cross-match and is fast acting. We hypothesized that PCC can rapidly reverse coagulopathy and reduce mortality in wICH.

Methods: We identified 130 consecutive adult wICH patients over five years from a prospectively collected database. 33 patients were excluded for death or withdrawal of care within 48 hours of admission and 8 patients were excluded for antecedent head trauma, leaving 89 patients for analysis. Forty patients received FFP and vitamin K (conventional therapy) and 49 received PCC in addition to conventional therapy. We compared 6-month mortality, time to INR normalization, quantity of FFP transfused, and thromboembolic complication rates between the two groups. We used logistic regression to adjust for important confounders.

Results: PCC-treated and conventional therapy patients had similar distributions of age, sex, co-morbidities, ICH location, initial blood pressure and INR. PCC-treated patients had a higher incidence of intraventicular hemorrhage (IVH) (67% vs 33%). PCC-treated patients required less FFP (mean 6.8 units vs 3.3 units, p<0.0001) and had faster time to INR normalization (mean 3.8 hrs vs 9.8 hrs, p<0.0001). Incidence of ICH expansion was low in both groups. There was no difference in the incidence of deep venous thrombosis and pulmonary embolism (p=0.236) or troponin elevation (p=0.573). There was no significant difference in 6-month mortality (p=0.437) after adjusting for age, ICH location, ICH volume, and presence of IVH.

Conclusions: PCC use in wICH was associated with shorter time to INR normalization and reduced FFP transfusion but was not associated with 6-month mortality in this cohort. There was no difference in thromboembolic complication rates between PCC-treated and FFP and vitamin K treated patients. Prospective trials of PCC are necessary to determine if its use can improve morbidity and mortality in wICH and to identify potential subgroups of wICH patients who may benefit from PCC.

Abstract 52: Early Elevation of Plasma Plasminogen Activator Inhibitor-1 is Associated with Vasospasm following Subarachnoid Hemorrhage

Background: While the mechanism of early brain injury following subarachnoid hemorrhage (SAH) remains unclear, animal studies suggest that SAH is associated with significant changes in the fibrinolytic cascade. Human data shows that SAH-related brain ischemia is associated with the polymorphism in plasminogen activator inhibitor 1 (PAI-1) promotor linked to higher plasma PAI-1 levels. However, human plasma PAI-1 has not been previously studied in SAH. We hypothesize that elevated plasma PAI-1 is associated with VSP and poor outcome in SAH.

Methods: In a prospective cohort of 61 SAH subjects, we compared plasma PAI-1 levels by ELISA (R&D Systems) on post-SAH days 1, 5, 7 and 14 with respect to angiographic VSP and to functional outcome at 3- and 6-months. Angiographic VSP was defined as >50% reduction in vessel caliber on post-SAH day 6-8 angiography. Poor functional outcome was defined as a modified Rankin score >2. Biomarker levels were compared using Wilcoxon rank sum test. Bonferroni correction was applied for multiple comparisons.

Results: Subjects with (n=25) and without VSP (n=36) were comparable in gender, Fisher and Hunt and Hess (HH) grade distribution, aneurysm treatment modality, and incidence of hydrocephalus. Subjects with VSP had lower mean age (50 vs. 56). Elevated plasma PAI-1 on post-SAH day 1 was strongly association with VSP (3.28 vs. 1.82 ng/mL; p=.0058) and showed a trend towards association with VSP on post-SAH day 5 (2.65 vs 1.83 ng/mL, p=0.05). Plasma PAI-1 levels were not associated with functional outcome at 3 or 6 months. Elevated plasma PAI-1 on post-SAH day 1 remained significantly associated with VSP (p=0.0155) after adjustment for age and HH and Fisher grades by logistic regression.

Conclusion: Early elevation of plasma PAI-1 on post-SAH day 1 is strongly and independently associated with angiographic VSP in this small prospective SAH cohort and may be a candidate biomarker for VSP. Future mechanistic studies with simultaneous measurements of tissue plasminogen activator (tPA) and tPA-PAI complex and larger clinical studies are necessary to understand the utility of PAI-1 as potential biomarker in SAH.

Abstract WMP114: Increased Big Endothelin-1 in Human Cerebrospinal Fluid is Associated with Vasospasm and Poor 3-month Outcome Following Subarachnoid Hemorrhage

Background Big endothelin (ET) is the precursor to ET-1, a potent vasoconstrictive peptide associated with vasospasm (VSP) in SAH. However, ET-1’s very short half-life limits its utility as a clinical biomarker. Big ET mediates in vitro microvascular vasoconstriction and has slower clearance, therefore may be a better candidate biomarker. We hypothesize that elevated CSF Big ET-1 is associated with VSP and poor outcome in SAH.

Methods We prospectively enrolled consecutive SAH subjects, banked serial CSF samples, and evaluated their modified Rankin scores (mRS) via telephone follow-up every 3 months. Poor functional outcome was defined as mRS>2. Angiographic VSP was defined as >50% reduction in caliber of any vessel on post-SAH day 7 cerebral angiogram. In 49 SAH subjects, we compared CSF big ET by ELISA on post-SAH days 1, 3, 5, and 7 with respect to VSP and outcome using student’s t-test or Wilcoxon rank sum test depending on data normality. Logistic regression was used to adjust for important confounders.

Results CSF big ET elevation on post-SAH day 1 is associated with poor 3-month outcome (4.2 vs. 2.0 ng/mL, p=0.0048), and big ET elevation on post-SAH day 3 shows trend towards association with poor 3-month outcome (1.15 vs. 3.09 pg/mL, p=0.057). CSF big ET level on post-SAH day 1 is significantly associated with 3-month outcome (p<0.0001) after adjusting for age, Hunt and Hess (HH) and Fisher grades and aneurysm treatment modality by logistic regression. CSF big ET elevation on post-SAH day 7 is associated with VSP (5.2 vs. 3.9 pg/mL, p=0.045). Logistic regression shows CSF big ET level on post-SAH day 7 is significantly associated with VSP (p=0.02) after adjusting for age, HH and Fisher grades and aneurysm treatment modality.

Conclusion Early elevation of CSF big ET is strongly and independently associated with SAH 3-month outcome after adjustment for important clinical confounders. CSF big ET elevation on post-SAH day 7 is also independently associated with angiographic VSP. A larger study with a replication cohort is necessary to validate big ET as a biomarker for SAH outcome and VSP. Further studies with concomitant measurements of endothelin-converting enzyme and ET-1 are necessary to elucidate the role of CSF big ET in VSP and brain injury following SAH.

Abstract 2834: Elevated Blood and Cerebrospinal Fluid Matrix Metalloproteinase-9 is Associated with Poor 3-month Outcome Following Subarachnoid Hemorrhage

Background There is growing evidence supporting the role of inflammation in early brain injury (EBI) and cerebral vasospasm following subarachnoid hemorrhage (SAH). Matrix Metalloproteinases (MMP) are released by inflammatory cells and can mediate EBI via disruption of the extracellular matrix. MMPs also cleave endothelin-1 (ET-1) into strongly vasoactive fragments and may thereby mediate vasospasm, which can further worsen SAH outcome. We hypothesize that elevated MMP-9 in human cerebrospinal fluid (CSF) is associated with vasospasm and SAH outcome, and therefore a potential clinical biomarker.

Methods We prospectively enrolled consecutive SAH subjects, banked serial blood and CSF samples, and evaluated their 3- and 6-month modified Rankins scores (mRS) via telephone follow-up. Angiographic vasospasm was defined as >50% reduction in vessel caliber on angiography on post-SAH day 6-8. Poor outcome was defined as mRS>2. We compared blood and CSF MMP-9 by ELISA on post SAH days 0-1, 2-3, 4-5, 6-8, and 10-14 in a cohort of SAH subjects (N=35) with respect to vasospasm and to 3-month outcome. Continuous variables were compared using student t-test or Wilcoxan rank sum test depending on data normality. Repeated measurements were analyzed using longitudinal regression.

Results The study population had a mean age of 53 years and has 54% female. Sixty percent of subjects presented with Hunt and Hess grade of 3 and above. Fifty-four percent developed vasospasm and 32% achieved poor 3-month outcome. Elevation of CSF MMP-9 throughout post SAH days 0-14 was associated with poor 3-month outcome (p=0.008). Specifically, elevated CSF MMP-9 on post SAH day 2-3 (p=0.05) and blood MMP-9 on post SAH day 4-5 (p=0.045) were associated with poor 3-month outcome ( Figure 1 ). Blood MMP-9 correlated strongly with blood leukocyte count (r=0.56, p=0.007). Neither CSF nor blood MMP-9 correlated with vasospasm.

Conclusion Early elevation of CSF and blood MMP-9 are associated with poor 3-month outcome but not with vasospasm in SAH. Leukocytes are likely a significant source of blood but not CSF MMP-9. Blood and CSF MMP-9 may mediate neuronal death in SAH via mechanisms independent of angiographic vasospasm. Further studies are necessary to determine the source of CSF MMP-9 and the mechanism by which it mediates poor outcome in SAH. Larger prospective studies are necessary to validate CSF MMP-9 as a predictive biomarker for SAH outcome.

Lacosamide in the treatment of acute recurrent seizures and periodic epileptiform patterns in critically ill patients

We investigated the safety, tolerability, and effectiveness of lacosamide (LCM) in patients with acute recurrent seizures or with periodic epileptiform activity captured during continuous EEG monitoring. A total of 17 patients received LCM; 12 patients received LCM as a second or third antiepileptic drug (AED), one patient as a fourth AED, and one patient as a fifth AED. No additional AEDs were introduced after LCM in 15 patients. Twelve patients responded to LCM with improvement in the seizures or periodic epileptiform activity. Two patients required further AED management or burst suppression. No adverse effects, including symptomatic bradycardia and allergic reactions, were seen for intravenous infusion dosages up to 300 mg. Eleven patients were eventually discharged on LCM. LCM is an important new AED in the add-on treatment of acute recurrent seizures and periodic epileptiform activity in critically ill patients.

Effects of supplemental 25-hydroxycholecalciferol on growth performance, small intestinal morphology, and immune response of broiler chickens

Three experiments were conducted to evaluate the effects of 25-hydroxycholecalciferol (25-OH-D(3)) on the growth performance, small intestinal morphology, and immune response of broiler chickens. In experiment 1, 25-OH-D(3) neither increased nor decreased weight gain and feed efficiency compared with the controls during the 39-d feeding period. Birds fed 25-OH-D(3) exhibited numerically higher phagocytosis (45%) than the controls (35%). In experiment 2, chicks were fed diets similar to those used in experiment 1 and were killed at 7, 14, 21, 28, and 35 d of age to determine the relative weight and histology of the small intestine. The relative weight of the small intestine from birds fed 25-OH-D(3) was numerically lower (P < 0.1) at 7 d of age. It was found that 25-OH-D(3) consistently resulted in longer (P < 0.05) villus length of the duodenum in 21- and 28-d-old birds and of the jejunum in 14- and 28-d-old birds. Shorter (P < 0.05) crypt depth was observed in the duodenum at 14 d of age and in the jejunum at 21 and 28 d of age. A higher (P < 0.05) ratio of villus length to crypt depth was also observed in the duodenum and jejunum at 14, 21, and 28 d of age of birds fed 25-OH-D(3). The thickness of muscle layer increased in the duodenum at 14, 28, and 35 d of age in birds fed 25-OH-D(3). In experiment 3, birds were orally challenged with either Luria-Bertani broth or Salmonella Typhimurium E29 at 7 and 14 d of age. Uninfected birds fed 25-OH-D(3) had lower total serum IgA at 14 d of age and lower total serum IgG at 21 d of age. However, infected birds fed 25-OH-D(3) produced higher (P < 0.1) total serum IgG at 21 d of age. The results of this study suggest that supplemental 25-OH-D(3) improves small intestinal morphology and protective humoral immunity to infection.

Bilateral Video-Assisted Thoracoscopic Thymectomy vs. Extended Transsternal Thymectomy in Myasthenia Gravis: A Prospective Study

The optimal approach to thymectomy remains controversial. This study is designed to prospectively compare the results between bilateral video-assisted thoracoscopic thymectomy (BVTx) and extended transsternal thymectomy (ETTx) in patients with myasthenia gravis (MG) without thymoma. Fifteen patients who had undergone BVTx and 16 patients who had undergone ETTx were compared for age, gender, severity of disease, preoperative duration of disease, operative time, intraoperative blood loss, postoperative complications, hospital stay, duration of chest tube drainage, thymic histopathology, pain perception by visual analog scale (VAS), remission and improvement rate, period of follow-up, and activities of daily living (ADL). Fisher's exact test, t test and paired t test were used for statistical analysis. BVTx had longer operative time and less intraoperative blood loss than that of the ETTx. Their remission rates and their degree of postoperative ADL improvement were not significantly different. However, the lowering of VAS was significantly greater in the sternotomy group at 3 months. All other parameters were not significantly different. No mortality was noted in the series. We consider BVTx as an effective alternative procedure to the transsternal approach for patients with nonthymomatous MG. As more and more people care about cosmetics, BVTx could become the future trend.

Fiber-optic bronchoscopic classification of inhalation injury: prediction of acute lung injury

BACKGROUND

Fiber-optic bronchoscopy is widely used for the early diagnosis of inhalation injury. However, there is no current bronchoscopic classification of inhalation injury for the prediction of acute lung injury (ALI). Our goal was to devise such a classification.

METHODS

Between February 1993 and January 2002, 167 patients with highly suspicious inhalation injuries were collected. All patients received fiber-optic bronchoscopy within 24 h after their accident. In total, 108 patients were diagnosed as positive under direct inspection. The patients were divided into three groups (G(1), G(2), and G(3)) according to the depth of mucosal damage. Six patients were found to be positive by biopsy and were assigned to group Gb. Of these 114 positive cases, 27 developed ALI. Meanwhile, 53 patients were diagnosed as negative; these patients were assigned to group G(0).

RESULTS

After analysis, the following results were noted: G(0) (n = 53), two ALI (3.8%); G(1) (n = 49), two ALI (4%); G(2) (n = 46), 15 ALI (33%); G(3)(n = 13),10 ALI (77%); Gb (n = 6), no ALI. We discovered that the deeper the mucosal injuries, the higher the rate of ALI. There were no deaths related to the procedure.

CONCLUSIONS

Fiber-optic bronchoscopy is a safe and effective method for the early diagnosis of inhalation injuries. Also, it is a good predictor of ALL. We hope that in the near future, this classification will serve as a treatment guideline for the early prevention of ALI. The more severe the damage, the more alert clinicians need to be to improve the patient's chances for survival.

Increased engraftment and GVHD after in utero transplantation of MHC-mismatched bone marrow cells and CD80low, CD86(-) dendritic cells in a fetal mouse model

BACKGROUND

Bone marrow transplantation (BMT) is the only known cure for a variety of inherited diseases and requires the administration of high doses of immunosuppressive and myeloablative therapy. Because the fetus is immunoincompetent early in gestation, in utero stem cell transplantation (IUT) could avoid the need for this toxic conditioning. A major limitation to date of IUT is the low level of engraftment and failure to induce tolerance. Dendritic cells (DC) are considered very potent antigen-presenting cells, but DC progenitors (pDC) are strongly tolerogenic.

METHODS

We examined the effect of donor pDC on the degree of engraftment and tolerance induction after IUT. Bone marrow-derived pDC (CD80low, CD86-) from male C57BL/6 mice (H2b) were injected with and without donor bone marrow (BM) intraperitoneally into 13 to 15-day BALB/c (H2d) fetuses. Engraftment was determined by flow cytometry and quantitative polymerase chain reaction and tolerance by skin grafts and the mixed lymphocyte reaction.

RESULTS

At 1-month posttransplant, mice that received BM+pDC showed a higher degree of engraftment (29+/-46%) than mice that received pDC-enriched cells or BM cells alone (0.11+/-0.70% and 1.71+/-1.66%, respectively, P<0.001). However, 5/19 recipients of BM+pDC died within 6 weeks; 4/5 had significant donor cell engraftment in blood and/or tissues. Also, these mice had evidence of graft-versus-host disease (GVHD). Two mice out of 15 long-term survivors in the BM+pDC group had virtually complete replacement of host with donor hematopoietic cells. Skin grafts and mixed lymphocyte reaction studies showed no durable tolerance induction other than in the two fully engrafted recipients of BM+pDC.

CONCLUSIONS

These results suggest that donor pDC, along with donor BM, can have a significant impact on engraftment of MHC-mismatched donor cells associated with an increased incidence of GVHD. However, marrow-derived pDC do not result in an increase in tolerance induction in utero even when microchimerism is present.

Novel cross-strand three-purine stack of the highly conserved 5'-GA/AAG-5' internal loop at the 3'-end termini of Parvovirus genomes

We have used two-dimensional nuclear magnetic resonance (2D-NMR), distance geometry (DG) and molecular dynamics / energy minimization (MD/EM) methods to study a 2 x 3 asymmetric internal loop structure of the highly conserved 5'-(GA)/(AAG)-5' bubble' present at the 3'-end hairpin of the single-stranded DNA genome of parvoviruses. This motif contains an unpaired adenosine stacked between two bracketed sheared G.A pairs. However, the phenomenal cross-strand G-G and A-A stacking in the tandem sheared G.A pairs has undergone considerable change. A novel three-purine stacking pattern is observed instead; the inserted A18 base is completely un-stacked from its neighboring G 17 and A 19 bases, but well stacked with the cross-strand A4 and G3 bases to form a novel A4/A18/G3 stack that is different from the double G/G, A/A or quadruple G/G/G/G stack present in the 5'-(GA)/(AG)-5' or 5'-(GGA)/(AGG)-5' motifs. Unlike the bulged purine residue that usually causes about 20 degree kink in the helical axis of the parent helix when bracketed by canonical G.C or A.T base pairs, no significant kink is observed in the present helix containing a bulged-adenine that is bracketed by sheared G.A pairs. The phosphodiesters connecting G3-A4 and G17-A18 residues adopt unusual zeta torsional angles close to the trans domain, yet that connecting A18-A19 residues resumes the normal zeta(g-) value. The well structured '5'-(GAA)/(AG)-5" internal loop in the parvovirus genomes explains its resistance to single-strand specific endonuclease susceptibility.

Quadruple intercalated G-6 stack: a possible motif in the fold-back structure of the Drosophila centromeric dodeca-satellite?

The purine-rich strand d(GTACGGGACCGA)(n) of the Drosophila centromeric dodeca-satellite sequence is highly conserved and was found to form stable fold-back structures in which the homopurine 5'-GGGA-3' sequence was determined to play a crucial role. Here, we report the stable formation of the d(GGGA)(2) motif in the stem of a DNA hairpin closed by a single-residue d(ACC) loop. Similar to the zipper-like d(GGA)(2) motif observed in the human centromeric (TGGAA)(n) sequence, the central four guanosine bases in the d(GGGA)(2) motif do not pair, but interdigitate to form an elongated zipper-like quadruple-intercalated G-6 stack bracketed by sheared G.A base-pairs. Comparison between the current d(GGGA)(2) structure and the published crystal d(GAAA)(2) structure implies that the alignment of the unpaired purine bases plays an important role in determining the minor groove width of the purine-rich d(GPuPuA)(2) motif. Similarity between the zipper-like motifs possibly present in the Drosophila centromeric dodeca-satellite sequence and in the human centromeric (TGGAA)(n) sequence led us to propose that these special zipper-like motifs may constitute common cores in organizing eukaryotic centromeres.

The solution structure of [d(CGC)r(amamam)d(TTTGCG)]2

The solution structure and hydration of a DNA.RNA hybrid chimeric duplex [d(CGC)r(amamam)d(TTTGCG)]2 in which the RNA adenines were substituted by 2'-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2'-OMe-RNA.DNA junction adopted an O4'-endo sugar conformation, while the other DNA residues including 3C in the DNA.2'-OMe-RNA junction, adopted C1'-exo or C2'-endo conformations. The observed NOE intensity of 2'-O-methyl group to H1' proton of 4am at the DNA.2'-OMe-RNA junction is much weaker than those of 5am and 6am. The 2'-O-methyl group of 4am was found to orient towards the minor groove in the trans domain while the 2'-O-methyl groups of 5am and 6am were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1' protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]2, there were no long-lived water molecules found in [d(CGC)r(amamam)d(TTTGCG)]2. This is probably due to the hydrophobic enviroment created by the 2'-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2'-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5 degrees C to 51.9 degrees C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNA.RNA hybrid and chimeric duplexes with 2'-modified RNA residues.

Solution structure of a DNA double helix incorporating four consecutive non-Watson-Crick base-pairs

A series of DNA 21-mers containing a variety of the 4 x 4 internal loop sequence 5'-CAAG-3'/3'-ACGT-5' were studied using nuclear magnetic resonance (NMR) methodology and distance geometry (DG)/molecular dynamics (MD) approaches. Such oligomers exhibit excellent resolution in the NMR spectra and reveal many unusual NOEs (nuclear Overhauser effect) that allow for the detailed characterization of a DNA hairpin incorporating a track of four different non-Watson-Crick base-pairs in the stem. These include a wobble C.A base-pair, a sheared A.C base-pair, a sheared A.G base-pair, and a wobble G.T base-pair. Significantly different twisting angles were observed between the base-pairs in internal loop that results with excellent intra-strand and inter-strand base stacking within the four consecutive mismatches and the surrounding canonical base-pairs. This explains why it melts at 52 degrees C even though five out of ten base-pairs in the stem adopt non-Watson-Crick pairs. However, the 4 x 4 internal loop still fits into a B-DNA double helix very well without significant change in the backbone torsion angles; only zeta torsion angles between the tandem sheared base-pairs are changed to a great extent from the gauche(-) domain to the trans domain to accommodate the cross-strand base stacking in the internal loop. The observation that several consecutive non-canonical base-pairs can stably co-exist with Watson-Crick base-pairs greatly increases the limited repertoire of irregular DNA folds and reveals the possibility for unusual structural formation in the functionally important genomic regions that have potential to become single-stranded.

Zipper-like Watson-Crick base-pairs

A series of DNA heptadecamers containing the DNA analogues of RNA E-like 5'-d(GXA)/(AYG)-5' motifs (X/Y is complementary T/A, A/T, C/G, or G/C pair) were studied using nuclear magnetic resonance (NMR) methodology and distance geometry (DG)/molecular dynamics (MD) approaches. Such oligomers reveal excellent resolution in NMR spectra and exhibit many unusual nuclear Overhauser effects (NOEs) that allow for good characterization of an unusual zipper-like conformation with zipper-like Watson-Crick base-pairs; the potential canonical X.Y H-bonding is not present, and the central X/Y pairs are transformed instead into inter-strand stacks that are bracketed by sheared G.A base-pairs. Such phenomenal structural change is brought about mainly through two backbone torsional angle adjustments, i.e. delta from C2'-endo to C3'-endo for the sugar puckers of unpaired residues and gamma from gauche(+) to trans for the following 3'-adenosine residues. Such motifs are analogous to the previously studied (GGA)(2) motif presumably present in the human centromeric (TGGAA)(n) tandem repeat sequence. The novel zipper-like motifs are only 4-7 deg. C less stable than the (GGA)(2) motif, suggesting that inter-strand base stacking plays an important role in stabilizing unusual nucleic acid structures. The discovery that canonical Watson-Crick G.C or A.T hydrogen-bonded pairs can be transformed into stacking pairs greatly increases the repertoire for unusual nucleic acid structural motifs.

Tolerance induction post in utero stem cell transplantation

The potential advantage of in utero HSC transplantation over a postnatal BMT is that early curative therapy could be given to an affected fetus, thus eliminating standard intensive immunosuppressive, marrow-ablative conditioning. It is apparent from studies in animals and humans that MHC-mismatched donor HSC of either fetal or adult origin can engraft in fetal recipients if the transplants are done sufficiently early in gestation. However, except for SCID, the percentage of donor pluripotent HSC that engraft is unacceptably low. We had hoped that for diseases such as thalassemia there would be a selective survival advantage for committed donor progenitor cells resulting in a high percentage of donor cell engraftment. At least based upon the experience in human fetuses with alpha- or beta-thalassemia, this has not been the case. Furthermore, for the majority of potential recipients of in utero HSC transplants, the marrow is non-defective, and the small percentage of pluripotent donor HSC that engraft would not be expected to selectively expand post-transplant. Our own results suggest that the non-defective fetal mouse and rhesus monkey are excellent models in which to study both stem cell engraftment, rejection, and tolerance induction. In our studies in non-defective mice with normal hematopoiesis, while the percentage of donor cells that are present is quite low, in only a small number of these animals were we able to induce permanent skin graft tolerance. Thus, while we found microchimerism in approximately 75% of recipients, less than 10% became tolerant. Even when we co-injected a large number of DC precursors, similar to what has been shown to induce tolerance to allogeneic liver, most of the animals failed to become tolerant to donor skin grafts. Interestingly, donor c-kit+ cells can be recruited with cytokines into the peripheral blood in engrafted mice, although these cells do not seem to be sufficient to induce tolerance to donor skin grafts, suggesting that the type (and location) of the engrafted donor cell plays a key role in tolerance induction. Our results in the fetal monkey model parallel those in the mouse, i.e., only a small number of donor cells engraft with limited tolerance induction. Interestingly, we found in our study of DC that GVHD was induced in those murine recipients of both allogeneic marrow and DC. It is likely that there were a sufficient number of mature DC in the preparation to facilitate a donor cytotoxic response towards the host. As a consequence there was also a significant increase in the percentage of donor cells that engrafted in the survivors. Future studies will focus on ways of blocking the graft vs host reaction while still maintaining the graft-promoting role of the donor T cell.

Video-assisted thoracoscopic management of mediastinal tumors

BACKGROUND

Many successful attempts at removing benign mediastinal tumors with the video-assisted thoracoscopic technique have been reported, but no formal report has been published regarding malignant mediastinal tumors treated with this technique. We report our preliminary experience with video-assisted thoracoscopic removal of mediastinal tumors, benign or malignant.

METHODS

Seven patients with mediastinal tumors treated with video-assisted thoracoscopic surgery were reviewed from January 1999 to April 2000. Their tumor pathologies included benign or malignant thymoma, neurilemmoma, and teratoma.

RESULTS

The mean operation time was 240 minutes. The mean blood loss was 173 mL. The mean insertion time of chest tubes was 3 days. The mean admission time was 6 days. No deaths occurred during the study. Morbidity occurred in 2 patients. No tumor recurrence has been seen during the mean follow-up of 7 months.

CONCLUSIONS

The short-term results support the feasibility of VATS in managing technically resectable mediastinal tumors. Yet the long-term prognosis for the malignant lesions is deferred and needs further study.

Natural abundance heteronuclear NMR studies of the T3 mini-loop hairpin in the terminal repeat of the adenoassociated virus 2

A DNA hairpin containing a T3 loop, as occurs in the terminal repeat of a popular gene therapy vector (Adenoassociated Virus 2, AAV2), has been extensively studied using homo- and heteronuclear NMR experiments. Almost complete assignment of the proton and carbon resonances, including H5'(Pro-S) and H5'(Pro-R) protons, has been accomplished at natural abundance. NOESY spectra in H2O and D2O have revealed many unusual NOEs, which, when combined with the epsilon, beta, gamma, and chi torsion angles determined from heteronuclear 1H-13C, 1H-31P, and 13C-31P coupling constants, have allowed for a more detailed picture of the T3 mini-loop hairpin. The three loop thymidines are all unpaired, yet are highly structured when bracketed by a 5'-GC...GC-3' stem sequence. The structure determined in this manuscript is considerably different from several other structures reported so far. Contrary to an RNA oligomer with a central U3 sequence that has the tendency to form a duplex with three U*U mismatches, the d(GAAGC-TTT-GCTTC) sequence exists mostly as a hairpin under millimolar NMR conditions. Since T3 triloop was found to be an essential element for the site-specific non-homologous integration of the AAV2 virus, and modification of the T3 loop residue abolishes such capability, the structure we report here may be of biological significance.

Elucidation of the solution structure of cardiotoxin analogue V from the Taiwan cobra (Naja naja atra)--identification of structural features important for the lethal action of snake venom cardiotoxins

The aim of the present study is to understand the structural features responsible for the lethal activity of snake venom cardiotoxins. Comparison of the lethal potency of the five cardiotoxin isoforms isolated from the venom of Taiwan cobra (Naja naja atra) reveals that the lethal potency of CTX I and CTX V are about twice of that exhibited by CTX II, CTX III, and CTX IV. In the present study, the solution structure of CTX V has been determined at high resolution using multidimensional proton NMR spectroscopy and dynamical simulated annealing techniques. Comparison of the high resolution solution structures of CTX V with that of CTX IV reveals that the secondary structural elements in both the toxin isoforms consist of a triple and double-stranded antiparallel beta-sheet domains. Critical examination of the three-dimensional structure of CTX V shows that the residues at the tip of Loop III form a distinct "finger-shaped" projection comprising of nonpolar residues. The occurrence of the nonpolar "finger-shaped" projection leads to the formation of a prominent cleft between the residues located at the tip of Loops II and III. Interestingly, the occurrence of a backbone hydrogen bonding (Val27CO to Leu48NH) in CTX IV is found to distort the "finger-shaped" projection and consequently diminish the cleft formation at the tip of Loops II and III. Comparison of the solution structures and lethal potencies of other cardiotoxin isoforms isolated from the Taiwan cobra (Naja naja atra) venom shows that a strong correlation exists between the lethal potency and occurrence of the nonpolar "finger-shaped" projection at the tip of Loop III. Critical analysis of the structures of the various CTX isoforms from the Taiwan cobra suggest that the degree of exposure of the cationic charge (to the solvent) contributed by the invariant lysine residue at position 44 on the convex side of the CTX molecules could be another crucial factor governing their lethal potency.

Hydration of [d(CGC)r(aaa)d(TTTGCG)](2)

We have studied the hydration and dynamics of RNA C2'-OH in a DNA. RNA hybrid chimeric duplex [d(CGC)r(aaa)d(TTTGCG)](2). Long-lived water molecules with correlation time tau(c) larger than 0.3 ns were found close to the RNA adenine H2 and H1' protons in the hybrid segment. A possible long-lived water molecule was also detected close to the methyl group of 7T in the RNA-DNA junction but not to the other two thymine bases (8T and 9T). This result correlates with the structural studies that only DNA residue 7T in the RNA-DNA junction adopts an O4'-endo sugar conformation (intermediate between B-form and A-form), while the other DNA residues including 3C in the DNA-RNA junction, adopt C1'-exo or C2'-endo conformations (in the B-form domain). Based on the NOE cross-peak patterns, we have found that RNA C2'-OH tends to orient toward the O3' direction, forming a possible hydrogen bond with the 3'-phosphate group. The exchange rates for RNA C2'-OH were found to be around 5-20 s(-1), compared to 26.7(+/-13.8) s(-1) reported previously for the other DNA.RNA hybrid duplex. This slow exchange rate may be due to the narrow minor groove width of [d(CGC)r(aaa)d(TTTGCG)](2), which may trap the water molecules and restrict the dynamic motion of hydroxyl protons. The distinct hydration patterns of the RNA adenine H2 and H1' protons and the DNA 7T methyl group in the hybrid segment, as well as the orientation and dynamics of the RNA C2'-OH protons, may provide a molecular basis for further understanding the structure and recognition of DNA.RNA hybrid and chimeric duplexes.

Stable formation of a pyrimidine-rich loop hairpin in a cruciform promoter

We have determined the solution structure of a TCC-loop hairpin in the cruciform promoter for the bacteriophage N4 virion RNA polymerase (N4 vRNAP). This hairpin and its complementary GGA-loop hairpin are extruded at physiological superhelical density and are required for vRNAP recognition. Contrary to its complementary GGA-loop, the three pyrimidines in the TCC-loop are all unpaired. However, with the help of two juxtaposed stem Watson-Crick G.C base-pairs, each nucleotide in the loop employs a special method to stabilize the hairpin structure. The resulting structures display extensive loop base-stacking rearrangement yet minor backbone distortion, which is largely accomplished through some loop zeta and alpha torsional angle changes. Consistent with the structural studies, UV melting of the GAAGCTCCGCTTC hairpin revealed a higher melting temperature (66 degrees C) than that of the GAACGTCCCGTTC hairpin (58 degrees C) with reversed stem G.C base-pairs, indicating significant contribution from the extra three loop-stem H-bonds. Thermodynamic parameters DeltaG degrees 25of the GAAGCTCCGCTTC hairpin and its complementary GAAGCGGAGCTTC hairpin are -4.1 and -4. 3 kcal/mol respectively, indicating approximately equal contribution of each hairpin to the cruciform formation of the N4 virion RNA polymerase promoter. No significant loop dynamics in the microsecond to millisecond NMR time-scale was observed, and the abundant well-defined exchangeable and non-exchangeable proton NOEs allowed us to efficiently determine a well-converged family for the final structures of the TCC-loop hairpin.

Finite-volume lattice Boltzmann schemes in two and three dimensions

Simple and practical finite-volume schemes for the lattice Boltzmann equation are derived in two and three dimensions through the application of modern finite-volume methods. The schemes use a finite-volume vortex-type formulation based on quadrilateral elements in two dimensions and trilinear hexahedral elements in three dimensions. It is shown that the schemes are applicable to domains with irregular boundaries of arbitrary shape in two and three dimensions.

Structural studies of symmetric DNA undecamers containing non-symmetrical sheared (PuGAPu):(PyGAPy) motifs

Interstrand purine-purine stacks originate from tandem sheared purine.purine pairing and represent one of the most important motifs in both DNA and RNA structures. Several RNA and DNA structures, solved recently in both solution and the solid state, contain these special motifs, which greatly increase the structural diversity of nucleic acid molecules. The direct evidence for the sheared purine-purine pairing at neutral pH in solution remains, however, elusive. In this manuscript, we have used high resolution NMR methods to study a series of symmetrical DNA duplexes containing two non-symmetrical 5'-(PuGAPu)/(PyGAPy)-3' motifs. Many strong- and medium-strength NOEs across the G.A base pair were detected in the H2O-NOESY spectra collected at a relatively low temperature (-5 degrees C). These NOEs, especially those from A-6NH2 to G-H1', G-H4', and G-2NH2, clearly define the proposed side-by-side sheared G.A pairing nature. Another interesting feature is the strong NOEs exhibited by the unpaired G-imino proton in the G.A pair to its own G-2NH2, which implies that G-2NH2 is involved in H-bonding with a base in the minor groove edge. The finding that non-symmetrical (PuGAPu):(PyGAPy) motif also form similarly stable structures loosens the requirement for a more restricted (PyGAPu)2 motif in forming the interstrand purine-purine stacks.

Finite-volume lattice Boltzmann method

We present a finite-volume formulation for the lattice Boltzmann method (FVLBM) based on standard bilinear quadrilateral elements in two dimensions. The accuracy of this scheme is demonstrated by comparing the velocity field with the analytical solution of the Navier-Stokes equations for time dependent rotating Couette flow and Taylor vortex flow. To demonstrate the flexibility of the scheme, we have also simulated a modified rotating Couette flow, where the inner cylinder has an elliptical shape. The results agree with those obtained from the traditional marker-and-cell method. The FVLBM scheme is applicable to arbitrarily shaped two-dimensional regions, and thus the range of applicability of the lattice Boltzmann method has been significantly extended.

Stable sheared A.C pair in DNA hairpins

Single-residue d(Pu1NPu2) (Pu1.Pu2=G.A, G.G or A.A) hairpin loops can be stably closed by sheared purine.purine pairs. These special motifs have been found in several important biological systems. We now extend these loop-closing base-pairs to a sheared purine. pyrimidine (A.C) pair at a neutral pH condition. High-resolution NMR spectroscopy, distance geometry, and molecular dynamics methods were used to study d(GTACANCGTAC) oligomers. Numerous idiosyncratic nuclear Overhauser enhancements, especially those across the A.C base-pair between C4NH2left and right arrow AH1', C4NH2left and right arrow AH2, and CH5left and right arrow AH2 proton pairs, clearly define the novel sheared nature of the closing A.C base-pair. This novel base-pair is possibly present in several biological systems and in two single-stranded DNA aptamers selected from oligonucleotide libraries.

Cross-strand purine-pyrimidine stack and sheared purine.pyrimidine pairing in the human HIV-1 reverse transcriptase inhibitors

Cross-strand homo purine-purine (G-G or A-A) stacks and sheared purine.purine pairing have been found to be important motifs in nucleic acid duplex structures. We now report novel cross-strand purine-pyrimidine (A-C) and hetero purine-purine (G-A) stacks that are established from a sheared purine.pyrimidine (A.C) pair adjacent to a sheared G.A pair in the 5'-AA/GC-3' sequence. This "internal loop" sequence is conserved in two families of single-stranded DNA inhibitors of the reverse transcriptase of type 1 human immunodeficiency virus. The distorted backbone of these inhibitors, resulting from the unique helical twists and kinks in the 5'-AA/GC-3' sequence, may be responsible for the increased affinities of these single-stranded DNA inhibitors as compared with other regular B-form duplex substrates. Two simple rules have been generalized to account for all reported cross-strand stacks.

Centromeric pyrimidine strands fold into an intercalated motif by forming a double hairpin with a novel T:G:G:T tetrad: solution structure of the d(TCCCGTTTCCA) dimer

The solution structures of the oligodeoxynucleotides d(CCCGTTTCC) and d(TCCCGTTTCCA) have been determined by two-dimensional NMR spectroscopy. These oligomers are part of a DNA box in human centromeric alpha satellite targeted by the centromere protein B (CENP-B). Both CENP-B and its recognition box in alphoid DNA are conserved in mammals, suggesting an important biological role. At acidic pH, d(CCCGTTTCC), d(TCCCGTTTCCA) and the full d(TCCCGTTTCCAACGAAG) CENP-B box strand all fold and dimerize in solution forming a stable bimolecular structure containing two GTTT hairpin loops that interact through a novel T : G : G : T tetrad. The stem region of the dimer is a four-stranded intercalated motif in which the hairpin monomers are parallel and held together by C : C+ hydrogen-bonding and intercalation. The loops are at the same end of the dimer and lie across the narrow grooves of the tetraplex. They are remarkably structured and stabilized by base-base cross-stacking, sugar-base stacking, and parallel G:G and antiparallel G:T pairing. In the d(TCCCGTTTCCA)2 structure, the intercalated motif is continued at the other end of the dimer with unpaired but stacked adenine and thymine bases. The possible biological implications of these structures are discussed.

Evidence for the involvement of catecholamines in the 2-DG-induced immunomodulatory effects in spleen

The role of catecholamines in immune changes associated with the metabolic stress of 2-deoxy-D-glucose (2-DG) was examined in this study. Male Lewis rats were pretreated with the nonselective beta-adrenergic receptor antagonist nadolol (0-0.5 mg/kg) and then received either a saline or 2-DG (500 mg/kg) injection. Nadolol attenuated the 2-DG-induced suppression of splenic T-cell mitogenic response and interferon-gamma production and increased nitric oxide production by macrophages in a dose-dependent manner. Conversely, nadolol did not attenuate the 2-DG-induced changes in immune parameters in peripheral blood leukocytes. These results suggest that the peripheral release of catecholamines is responsible for 2-DG-induced splenic immune alterations, whereas the peripheral release of catecholamine is not responsible for 2-DG-induced blood immune alterations. Furthermore, the neuroendocrine mechanisms responsible for splenic immune changes induced by the metabolic stress of 2-DG administration were the same as those involved in immune changes induced by physical and psychological stress. Thus, this study suggests that common neuroendocrine pathways exist for several types of stress-induced immunomodulations.

Sheared purine x purine pairing in biology

The Watson-Crick G x C and A x T base-paired DNA duplex has been the single most important milestone in modem molecular biology. However, it is possible that other types of stable DNA structures besides the double helix might exist, since only about 5% of the human chromosome is transcribed and expressed. Stable, four-stranded G-tetraplex DNA structures occur in the extensive tandem repeated sequences at the telomeres of chromosome. Formation of stable triplexes of the Py x Pu x Py or Pu x Pu x Py type have been implicated at the control regions of certain human genes. We review and discuss the various types of DNA duplex structures containing stable sheared base-pairs and compare their structural characteristics with that of B-DNA. Pu x Pu structural motifs are found in the highly conserved sequences at the replication origins of several single-stranded DNA viruses and in the peri-centromeric regions of human chromosomes, and may be involved in important biological functions, such as viral DNA replication and centromere formation.

Hairpin loops consisting of single adenine residues closed by sheared A.A and G.G pairs formed by the DNA triplets AAA and GAG: solution structure of the d(GTACAAAGTAC) hairpin

The DNA undecamers GTACAAAGTAC (AAA 11-mer) and GTACGAGGTAC (GAG 11-mer) have been studied in solution by high-resolution NMR spectroscopy. Both duplexes form stable hairpins containing single deoxyadenosine loops and stems containing five base-pairs that are closed at the loop end by sheared AxA and GxC pairs, respectively. These molecules thus contain new AAA and GAG loop turn motifs. All protons, including the chiral H5'/H5" protons of the loop residues, were assigned using NOESY, DQF-COSY and heteronuclear 1H-31P COSY experiments. The backbone torsion angles were constrained using experimental data from NOE crosspeaks, three-bond 1H-1H coupling constants and four-bond 1H-31P coupling constants and four-bond 1H-31P coupling constants. The AAA and GAG 11-mers form similar structures in solution. The detailed structure of the AAA 11-mer was determined by the combined use of NMR, distance geometry and energy minimization methods. This structure exhibits good stacking of the loop adenosine base on the closing 5Ax7A sheared pair, with the 6A base stacking on the 5A base and the 6A deoxyribose stacking with the 7A base. All sugars in the AAA 11-mer hairpin adopt the typical DNA C2'-endo conformation and a sharp backbone turn occurs between residues 6A and 7A. This loop turn is brought about mainly by a change in the backbone phosphate torsion angles from zeta(g-) alpha(g-) to zeta(g+) alphat(g+) at the turn. The gamma torsion angle of residue 7A in the closing sheared pair also changes from gauche+ to trans. In Pu1NPu2 loop turns of the GCA, AAA and GAG types, the chemical shift of the H4' proton of the loop deoxyribose depends on the nature of Pu2; this reflects the stacking of the loop sugar on the Pu2 base and the different ring current effects of A or G in this position.

Characterization of the effect of 2-deoxy-D-glucose(2-DG) on the immune system

This study was designed to characterize the effects of the metabolic stress of administration of 2-deoxy-d-glucose (2-DG, 500 mg/kg) on immune function. Male Lewis rats were exposed to one or five injections (one every 48 h) of 2-DG. Control rats received saline injections. Administration of 2-DG induced a reduction of total leukocytes in the spleen, thymus, and blood. The reduction was most prominent in animals that received five injections of 2-DG. The ratio of CD4(+)/CD8(+) in the spleen was decreased due to a significant increase of CD8(+) T-cell subpopulation. Additionally, 2-DG induced a suppression of mitogenic responsiveness and IFN-gamma production in both whole blood and spleen lymphocytes. The production of IL-1 and IL-2 was significantly reduced in the blood, but not in the spleen. Conversely, there was a significant increase in nitric oxide production in cultures of Con A-, PHA-, and LPS-stimulated splenocytes from 2-DG-injected animals compared with saline-injected controls. In blood cultures stimulated with Con A and PHA, the nitric oxide production of the group that received five injections of 2-DG was significantly higher than in the group that received one injection of 2-DG or saline. These results demonstrated that the metabolic stress 2-DG induced a downregulation of Th 1 cellular immune function in a manner similar to physical and psychological stressors. Additionally, the use of 2-DG in rats provided an important model with which to study metabolic stress.

A single G-to-C change causes human centromere TGGAA repeats to fold back into hairpins

Recently, we established that satellite III (TGGAA)n tandem repeats, which occur at the centromeres of human chromosomes, pair with themselves to form an unusual "self-complementary" antiparallel duplex containing (GGA)2 motifs in which two unpaired guanines from opposite strands intercalate between sheared G.A base pairs. In separate studies, we have also established that the GCA triplet does not form bimolecular (GCA)2 motifs but instead promotes the formation of hairpins containing a GCA-turn motif in which the loop contains a single cytidine closed by a sheared G.A pair. Since TGCAA is the most frequent variant of TGGAA found in satellite III repeats, we reasoned that the potential of this variant to form GCA-turn miniloop fold-back structures might be an important factor in modulating the local structure in natural (TGGAA)n repeats. We report here the NMR-derived solution structure of the heptadecadeoxynucleotide (G)TGGAATGCAATGGAA(C) in which a central TGCAA pentamer is flanked by two TGGAA pentamers. This 17-mer forms a rather unusual and very stable hairpin structure containing eight base pairs in the stem, only four of which are Watson-Crick pairs, and a loop consisting of a single cytidine residue. The stem contains a (GGA)2 motif with intercalative 14G/4G stacking between two sheared G.A base pairs; the loop end of the stem consists of a sheared 8G.10A closing pair with the cytosine base of the 9C loop stacked on 8G. The remarkable stability of this unusual hairpin structure (Tm = 63 degrees C) suggests that it probably plays an important role in modulating the folding of satellite III (TGGAA)n repeats at the centromere.

On the relative ability of centromeric GNA triplets to form hairpins versus self-paired duplexes

While tandem repeats of the human centromere DNA pentamer sequence TGRAA form stable "self-complementary" [TGRAATGRAA]2 duplexes (R = G or A) containing the GA-bracketed unpaired purine stack motif, their phase-shifted variants NAATGNAATG (N = A, G, C, T) were found to exist in solution as an equilibrium mixture of a duplex containing the GA-bracketed unpaired stack motif and a hairpin containing a single-residue loop closed by a sheared G x A pair. The stability of the hairpin form relative to duplex form of GNA triplets was found to be GCA>GAA/GTA>>GGA, with the CAATGCAATG sequence mostly in the hairpin form and the GAATGGAATG sequence mostly in the [GAATGGAATG]2 duplex form. The chemical shifts of the H1' and H4' protons of the central N residue in GNA triplets were found to differ markedly in the duplex and hairpin forms and are diagnostic indicators of which conformation the oligonucleotide adopts. Comparison between the structures of the G x A-closed C loop motif and the G x A-bracketed unpaired G-stack [GGA]2 motif reveals remarkably similar stacking by the loop C residue and the intercalated G residue on the adjacent sheared G x A pair. The anomalous upfield chemical shifts of the H1' and H4' protons in [GGA]2 motifs and the H4' proton in GCA loops, and the different sugar conformations in these two motifs, can be explained by interstrand versus intrastrand stacking of the central (G or C) deoxyribose with the adenine base. Based on these studies, a DNA sequence GTGGAATGGAATGGAAC was designed and shown to form a duplex containing three [GGA]2 motifs, while its 9G-->9C analog GTGGAATGCAATGGAAC was found to adopt a stable hairpin containing a (GGA)2 motif in the stem and a G x A-closed single C-loop.

The structure of a novel DNA duplex formed by human centromere d(TGGAA) repeats with possible implications for chromosome attachment during mitosis

The solution structure of the DNA duplex [GTGGAATGGAAC]2 containing a tandem repeat of the human centromere (TGGAA)n unit has been determined by two-dimensional nuclear magnetic resonance (2D-NMR), distance geometry (DG) and molecular dynamics/energy minimization (MD/EM) methods. This remarkably stable "self-complementary" antiparallel duplex contains a tandem repeated motif in which unpaired guanine residues from opposite strands intercalate and costack between sheared G.A pairs. Twelve independent refined structures were determined from the NMR data and found to converge to a single family of closely related structures with pair-wise r.m.s.d. values of 0.55 +/- 0.25 Angstrum. All sugar residues are in the normal C2'-endo conformation except for the unpaired guanosines, which are in the unusual C3'-endo conformation. The guanosine residues of the bracketing G.A pairs have high-antiglycosidic torsion angles and zeta backbone torsion angles close to the trans domain. The structure exhibits many unusual interstrand interactions, including base-sugar stacking, base-phosphate hydrogen bonding and cross-strand base stacking. The [GGA]2 unit contains a stack of four contiguous guanine residues, all of which have their hydrogen-bonding surface (N2H-N1H-O6-N7) exposed to solvent and available for interaction with other bases or ligands. This unexpected property may explain the unique morphology and function of the human centromere in mitosis.

Structure of a single-cytidine hairpin loop formed by the DNA triplet GCA

In certain contexts the DNA triplet GGA, when juxtaposed on opposite strands of a DNA duplex, shows the unusual property of pairing with itself in an antiparallel orientation to form the (GGA)2 motif. In this motif the central guanines do not pair but intercalate and stack between sheared G.A pairs. Similar studies with GCA triplets reveal that they do not form analogous paired (GCA)2 motifs but instead strongly promote formation of a hairpin, the structure of which is now reported here. The GCA hairpin loop consists of a single cytidine residue closed by a sheared G.A pair and this structure is discussed in the context of triplet expansions in triplet-repeat diseases.

Conformation of the propeptide domain of factor IX

The propeptide domain in the precursor forms of blood clotting proteins contains the recognition sequences for gamma-carboxylase. In hemophilia B, several point mutations in this propeptide domain are responsible for the inherited disease. A peptide containing the propeptide sequence of factor IX was synthesized by solid phase methods. Two dimensional 1H-NMR and CD studies indicate that this peptide motif adopts an alpha-helical structure in a 40% trifluoroethanol-containing aqueous solution. The results suggest that the amphipathic alpha-helix within the propeptide domain of factor IX could create a recognition surface for gamma-carboxylase. The influences of mutations and their relationship with the alpha-helical structure are discussed.

Histopathologic studies of gastric mucosa following gastric substitution in benign and malignant esophageal disease

Gastric interposition was performed and prospectively studied in 9 patients with esophageal cancer, 1 patient with esophageal neurofibroma and 5 with corrosive esophageal stricture. The postoperative follow-up periods were between 6 to 68 months with a mean of 28.6 months. The subjects were then endoscopically reviewed. Twelve of them were macroscopically normal. The others exhibited signs of inflammation and hyperemia. Mucosal biopsies were obtained at the upper and lower third of the graft. The histologic findings were compared with those of the preoperative specimens. Among the 15 post-operative specimens, only minute histologic changes were seen. Three patients whose proximal grafts showed inflammatory signs revealed congestion. Another 2 patients exhibited granulocyte infiltration in the mucosa of the distal third. The mucosal structure of the remaining 10 patients was similar to that of the preoperative graft. In conclusion, the macroscopic and microscopic changes were few and minimal although there were alterations in function, physiology and location of the stomach.

The unusual structure of the human centromere (GGA)2 motif. Unpaired guanosine residues stacked between sheared G.A pairs

The centromere of human chromosomes contains multiple repeats of the DNA sequence d(TGGAA)n. This sequence has the interesting property of pairing with itself to form stable duplexes. We have determined the solution structure of the unusual DNA duplex 5'-TGGAATGGAA:TGGAATGGAA-3' at atomic resolution. The duplex contains unpaired staggered guanosine residues, which co-stack by intercalation between sheared G.A and A.G base-pairs to form an interesting new structural motif, the GA-bracketed G-stack. The TGGAA repeat unit contains six "steps", four of which are not Watson-Crick base-pairs.

Use of glutaraldehyde solution in the treatment of acute aortic dissections

We report on a promising method for toughening and strengthening the fragile aortic wall that involves the direct application of a 25% glutaraldehyde solution and that has proved to be both technically simple and safe. The operation was successfully employed in 5 patients with acute aortic dissections, 3 with a Stanford type A and 2 with a type B dissection. Histologic examination of the glutaraldehyde-treated portions of the aortic wall showed no detectable difference between them and the sections of untreated aortic wall. All patients survived the operation. The duration of follow-up ranged from 9 to 31 months (mean, 14.0 months). All 5 patients were in good condition at the time of the last follow-up. The preliminary results indicate that the use of a 25% glutaraldehyde solution to strengthen the aortic wall during operations for the repair of acute aortic dissections, regardless of whether they are type A or type B, may reduce the incidence of catastrophic perioperative bleeding and promote favorable results.

DNA sequence GCGAATGAGC containing the human centromere core sequence GAAT forms a self-complementary duplex with sheared G.A pairs in solution

The DNA sequence dGCGAATGAGC has a well-resolved, two-dimensional nuclear Overhauser (NOESY) spectrum that is suitable for high quality solution structure determination by NMR methods; in solution this sequence forms a stable self-complementary duplex containing sheared G.A base-pairs. A total of 220 distance constraints derived from time-dependent NOE measurements were collected and refined by repeated back-calculation of the NOESY spectra. Distance information from imino proton studies and from exclusive two-dimensional correlated spectroscopy (E. COSY) and/or linewidth analysis was included in the structure calculation using the program DSPACE 4.2, followed by restrained energy minimization with the program DISCOVER using the AMBER force field. The energies of the distance geometry (DG) structures decreased rapidly in the first few cycles and approached -510 +/- 3 kcal after 1000 cycles of conjugate gradient minimization (about 540 kcal lower than in the initial DG structures). All 15 final DG structures converged to a single family of closely related structures with pair-wise r.m.s.d. values of 0.96 +/- 0.34 A, which was further reduced by energy minimization to 0.70 +/- 0.35 A. Rather unusual structural features of the duplex are revealed in the final structures. The results indicate that, in addition to normal sequences with standard base-pairing, unusual nucleic acid structures can also be determined in solution with quite high precision by NMR/distance geometry methods.

Imaging diagnosis of cavernous hemangioma of the rib--one case report and review of the literature

Osseous hemangioma is a benign neoplasm, rarely located in the ribs. A 56-year-old female patient without specific complaint had a large extrapleural lesion on chest posteroanterior radiograph. Expansile destruction of left seventh rib and relatively fine trabeculation were noticed in the mass from plain roentgenogram and computed tomography (CT). Contrast enhancement in noncalcified component of the lesion was revealed. Pleural effusion, lung parenchymal or mediastinal abnormality were not identified. Resection of the lesion with part of the originating rib was carried out. The pathologic diagnosis was cavernous hemangioma. We present a case with a large rib hemangioma which often leads to difficulty in radiologically differential diagnosis with other common malignant rib tumors. We also review the literature about hemangioma and malignant neoplasms of the ribs.

[Variations in ATPase activities of erythrocytic membrane and endocytic ionic levels in cases with pregnancy induced hypertension]

The ATPase activities of erythrocytic membrane and endocytic ionic concentration were determined in 30 cases with pregnancy induced hypertension (PIH), 25 normal pregnancies and 20 non-pregnant controls. The activities of Na(+)-K(+)-ATPase and Ca(++)-ATPase were found significantly lower in PIH than those in the controls, but Mg(++)-ATPase activity revealed no Na+ and Ca++ values were significantly higher while Mg++ obviously lower in those with PIH than in the controls, and K+ was almost the same in the three groups. These findings suggested a close relationship between the pathogenesis of PIH and the abnormal ATPase activities and ionic levels.

Spontaneous haemothorax: an unusual presentation of primary lung cancer

An unusual case of spontaneous haemothorax caused by a subpleural primary lung cancer is reported. Tumour invasion of the pulmonary vessels and visceral pleura was the possible cause.

Hepsin, a putative cell-surface serine protease, is required for mammalian cell growth

Hepsin was previously identified as a putative cell-surface serine protease. When hepatoma cells were treated with anti-hepsin antibodies, their growth was substantially arrested, suggesting the requirement of hepsin molecules present at the cell surface for normal cell growth. This was further supported by a gross inhibition of cell growth with hepsin-specific antisense oligonucleotides. Upon treatment of cells with antisense oligonucleotides, rapid reduction in cellular hepsin was observed. This reduction in cellular hepsin levels was accompanied by drastic morphological changes. Various tissues in the developing mouse embryo showed greatly elevated hepsin levels in regions of active proliferation. These results indicate that hepsin plays an essential role in cell growth and maintenance of cell morphology.