A Geometric Clustering Tool (AGCT) to robustly unravel the inner cluster structures of time-series gene expressions.

Systems biology aims at holistically understanding the complexity of biological systems. In particular, nowadays with the broad availability of gene expression measurements, systems biology challenges the deciphering of the genetic cell machinery from them. In order to help researchers, reverse engineer the genetic cell machinery from these noisy datasets, interactive exploratory clustering methods, pipelines and gene clustering tools have to be specifically developed. Prior methods/tools for time series data, however, do not have the following four major ingredients in analytic and methodological view point: (i) principled time-series feature extraction methods, (ii) variety of manifold learning methods for capturing high-level view of the dataset, (iii) high-end automatic structure extraction, and (iv) friendliness to the biological user community. With a view to meet the requirements, we present AGCT (A Geometric Clustering Tool), a software package used to unravel the complex architecture of large-scale, non-necessarily synchronized time-series gene expression data. AGCT capture signals on exhaustive wavelet expansions of the data, which are then embedded on a low-dimensional non-linear map using manifold learning algorithms, where geometric proximity captures potential interactions. Post-processing techniques, including hard and soft information geometric clustering algorithms, facilitate the summarizing of the complete map as a smaller number of principal factors which can then be formally identified using embedded statistical inference techniques. Three-dimension interactive visualization and scenario recording over the processing helps to reproduce data analysis results without additional time. Analysis of the whole-cell Yeast Metabolic Cycle (YMC) moreover, Yeast Cell Cycle (YCC) datasets demonstrate AGCT's ability to accurately dissect all stages of metabolism and the cell cycle progression, independently of the time course and the number of patterns related to the signal. Analysis of Pentachlorophenol iduced dataset demonstrat how AGCT dissects data to identify two networks: Interferon signaling and NRF2-signaling networks.

Increasing Fractional Doses Increases the Probability of Benign PSA Bounce in Patients Undergoing Definitive HDR Brachytherapy for Prostate Cancer.

PURPOSE: Prostate-specific antigen (PSA) bounce is a temporary elevation of the PSA level above a prior nadir. The purpose of this study was to determine whether the frequency of a PSA bounce following high-dose-rate (HDR) interstitial brachytherapy for the treatment of prostate cancer is associated with individual treatment fraction size. METHODS AND MATERIALS: Between 1999 and 2014, 554 patients underwent treatment of low- or intermediate-risk prostate cancer with definitive HDR brachytherapy as monotherapy and had ≥3 subsequent PSA measurements. Four different fraction sizes were used: 950 cGy × 4 fractions, 1200 cGy × 2 fractions, 1350 cGy × 2 fractions, 1900 cGy × 1 fraction. Four definitions of PSA bounce were applied: ≥0.2, ≥0.5, ≥1.0, and ≥2.0 ng/mL above the prior nadir with a subsequent return to the nadir. RESULTS: The median follow-up period was 3.7 years. The actuarial 3-year rate of PSA bounce for the entire cohort was 41.3%, 28.4%, 17.4%, and 6.8% for nadir +0.2, +0.5, +1.0, and +2.0 ng/mL, respectively. The 3-year rate of PSA bounce >0.2 ng/mL was 42.2%, 32.1%, 41.0%, and 59.1% for the 950-, 1200-, 1350-, and 1900-cGy/fraction levels, respectively (P=.002). The hazard ratio for bounce >0.2 ng/mL for patients receiving a single fraction of 1900 cGy compared with those receiving treatment in multiple fractions was 1.786 (P=.024). For patients treated with a single 1900-cGy fraction, the 1-, 2-, and 3-year rates of PSA bounce exceeding the Phoenix biochemical failure definition (nadir +2 ng/mL) were 4.5%, 18.7%, and 18.7%, respectively, higher than the rates for all other administered dose levels (P=.025). CONCLUSIONS: The incidence of PSA bounce increases with single-fraction HDR treatment. Knowledge of posttreatment PSA kinetics may aid in decision making regarding management of potential biochemical failures.

Robotic single site staging in endometrial cancer: A multi-institution study.

OBJECTIVE: To evaluate the feasibility and the safety of robotic single site hysterectomy (RSSH) plus or less pelvic lymphadenectomy in FIGO stage I-II endometrial cancer. MATERIALS AND METHODS: We prospectively collected patient demographics, operative times, complications, pathologic results, and length of stay on all patients who underwent RSSH plus or less pelvic lymphadenectomy for clinical FIGO stage I or occult stage II endometrial carcinoma. RESULTS: From January 2012 to February 2015, 125 patients were included in our study. The median age of the patients was 59 years (range, 35-84 years) and the median body mass index was 27 kg/m(2) (range, 19-52 kg/m(2)). One patient was converted to vaginal surgery due to problems of hypercapnia. The median docking time, console time, and total operative time was 11 min (range, 4-40 min), 80 min (range, 20-240 min) and 122 min (range, 35-282 min), respectively. The median blood loss was 50 ml (range, 10-250 ml). No laparoscopic/laparotomic conversion was registered. Twenty one patients underwent pelvic lymphadenectomy (16.8%) and the median pelvic lymph nodes was 13 (range, 3-32). The median time to discharge was 2 days (range, 1-3 days). No intra-operative complications occurred, while we observed 10 (8%) early post-operative complications. CONCLUSION: RSSH plus or less pelvic lymphadenectomy is technically feasible, safe and reproducible and could be the treatment of choice for patients affected by FIGO stage I-II endometrial cancer. However, randomized controlled trials are needed to confirm these results.

Phase 1 study of PTK787/ZK 222584, a small molecule tyrosine kinase receptor inhibitor, for the treatment of acute myeloid leukemia and myelodysplastic syndrome.

PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting vascular endothelial growth factor (VEGF) receptor tyrosine kinases, including VEGFR-1/Flt-1, VEGFR-2/KDR, VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase and the c-kit protein tyrosine kinase. The objective of this Phase I study was to evaluate the safety, tolerability, biologic activity and pharmacologic profile of PTK/ZK administered orally, twice daily, on a continuous dosing schedule in patients with primary refractory or relapsed acute myeloid leukemia (AML), secondary AML, poor-prognosis de novo AML or advanced myelodysplastic syndrome (MDS). Acute myeloid leukemia patients for whom PTK/ZK monotherapy was ineffective could receive PTK/ZK combined with standard induction chemotherapy. Sixty-three patients received PTK/ZK at doses of 500-1000 mg orally b.i.d. Safety and pharmacokinetic data were collected. Responses were evaluated according to standard bone marrow and peripheral blood criteria. At 1000 mg b.i.d., dose-limiting toxicities of lethargy, hypertension, nausea, emesis and anorexia were observed. Other adverse events related to PTK/ZK were dizziness, weakness, fatigue, diarrhea and pruritus; these were generally mild and reversible. Pharmacokinetic data showed that steady state was reached by day 14, there was no accumulation with repeat dosing and there was no significant increase in exposure at steady state beyond the maximum tolerated dose (MTD). Complete remission was observed in five of 17 AML patients treated with PTK/ZK combined with chemotherapy. In conclusion, the MTD of PTK/ZK is 750 mg orally b.i.d. The drug is generally well tolerated and can be given in combination with chemotherapy for patients with MDS and AML.

Neurotransmitter-stimulated ion transport by cultured porcine vas deferens epithelium.

A collagenase-based dissociation technique has been developed to routinely establish monolayer cultures of freshly isolated porcine vas deferens epithelium. Cells isolated from each tissue are transferred to 25-cm(2) tissue culture flasks and grown in a standard cell culture medium. Flasks reach confluency in 3-4 days, and cells are subsequently seeded onto permeable supports. Cultured cells display a monolayer cobblestone appearance and are immunoreactive to anti-ZO-1 and anti-cytokeratin antibodies. Electron microscopy is employed to demonstrate the presence of junctional complexes and microvilli. When evaluated in modified Ussing chambers, cultured monolayers exhibit a basal lumen negative potential difference, high electrical resistance (>1,000 Omega. cm(2)), and respond to norepinephrine, vasopressin, ATP, adenosine, and histamine, with changes in short-circuit current indicative of anion secretion. Responses are significantly attenuated in Cl(-)- and/or HCO-free solutions. Attempts to further optimize culture conditions have shown that chronic exposure to insulin increases proliferation rates. Thus the culture method described will reliably produce viable neurotransmitter-responsive cell monolayers that will allow for the characterization of vas deferens epithelial function and associated control mechanisms.

Distal thoracic aorta as inflow for the treatment of chronic mesenteric ischemia.

PURPOSE: Mesenteric revascularization for chronic mesenteric ischemia (CMI) traditionally involves antegrade or retrograde bypass graft originating from the supraceliac or infrarenal aorta. The distal thoracic aorta (DTA) may provide a better inflow source than the abdominal aorta. The purpose of this study was to evaluate the results with the DTA used as inflow for the surgical treatment of CMI. METHODS: All patients undergoing mesenteric revascularization for CMI with grafts originating from the DTA were identified from 1990 to 1999. A ninth interspace thoracoretroperitoneal incision was used for exposure, and distal aortic flow was maintained by use of a partial occlusion clamp. RESULTS: Eighteen consecutive patients with CMI underwent mesenteric bypass grafting with the DTA used as inflow. All patients were admitted with chronic abdominal pain or weight loss, with two (12%) requiring urgent revascularization because of acute exacerbation of chronic symptoms. Fourteen (78%) patients had both celiac and superior mesenteric artery bypass grafts placed, and three (17%) patients had superior mesenteric artery grafts alone. There was one (6%) perioperative death and three (17%) major complications. There was no kidney failure, mesenteric infarction, or spinal cord ischemia. The life-table survival rate was 89%, 89%, and 76% at 1, 3, and 5 years, respectively. All 18 patients remained symptom free and required no additional procedures to assist patency. There was no evidence of graft stenosis or occlusion (100% patency) for those grafts evaluated objectively during the mean follow-up of 34.8 months (range, 1-97 months). CONCLUSIONS: Antegrade mesenteric revascularization with the DTA used as inflow is associated with low morbidity and mortality rates. Furthermore, it provides excellent midterm patency and survival results and should be considered as a primary approach for reconstruction of patients with CMI.

Neuroglandular synapses in the pharynx of the sea anemone Aiptasia pallida (Cnidaria, Anthozoa).

Scanning and transmission electron microscopy of the pharynx of the sea anemone Aiptasia pallida revealed a heavily ciliated epidermis and two types of gland cells not known previously to be innervated. By tracing serial cross sections of the pharynx, we located and characterized two types of neuroglandular synapses (i.e., those having clear vesicles and those with dense-cored vesicles). The diameters of the vesicles at each synapse were averaged; clear vesicles ranged from 70 to 103 nm in diameter and were observed at synapses to both mucous and zymogenic gland cells. Dense-cored vesicles ranged from 53 to 85 nm in diameter and were observed at synapses to two mucous gland cells. One mucous gland cell had three neuroglandular synapses, one with clear vesicles and two with dense-cored vesicles. The occurrence of either clear or dense-cored vesicles at neuroglandular synapses suggests that at least two types of neurotransmitter substances control the secretion of mucus in the sea anemone pharynx. To date, only clear vesicles have been observed at a neurozymogenic gland cell synapse in the pharynx. No evidence of immunoreactivity to phenylethanolamine-N-methyl transferase was observed at neuroglandular synapses, suggesting that adrenaline is not a transmitter in the pharynx of A. pallida.

Sural artery pseudoaneurysms after knee arthroscopy: treatment with transcatheter embolization.

Vascular injury of the popliteal artery or its branches after knee arthroscopy is a rare but potentially devastating complication. We report two cases of sural artery branch pseudoaneurysms resulting from knee arthroscopy. Both patients were successfully treated with transcatheter embolization of the pseudoaneurysms. the diagnosis and treatment options of this unusual injury are discussed.

Neurotransmitter-stimulated ion transport across cultured bovine mammary epithelial cell monolayers.

Bovine mammary epithelial (BME-UV) and myoepithelial (BMM-UV) cell lines were acquired with the goal of developing an in vitro model of mammary epithelia for the study of ion transport. The bovine mammary cell lines were successfully cultured on commercially available permeable supports, and results suggest that mammary epithelial cells, but not myoepithelial cells, form tight junctions necessary to perform a barrier function. Electrogenic ion transport was not observed in basal conditions. Acute exposure to norepinephrine or forskolin caused prototypic increases in short circuit current accompanied by a reduction in transmural resistance indicative of anion secretion through a conductive pathway. Bumetanide and N-(4-methyphenylsulfonyl)-N'-(4-trifluoro-methylphenyl)urea, inhibitors of Na+/K+/Cl- cotransport and cystic fibrosis transmembrane conductance anion channels, respectively, reduced forskolin-stimulated ion transport. Amiloride, an inhibitor of epithelial sodium channels, had no effect on basal or forskolin-stimulated ion transport. However, naturally occurring and synthetic corticosteroids induced the expression of amiloride sensitive current indicative of sodium absorption. Chronic exposure to increased apical ionic strength and/or reduced carbohydrate concentration were associated with reduced transepithelial resistance although forskolin-stimulated ion transport was unaffected. These results demonstrate that neurotransmitters and steroid hormones act directly on bovine mammary epithelial cells to acutely and chronically modulate the volume and composition of their secretions. The in vitro system that we describe can be further exploited to characterize cellular and molecular mechanisms associated with mammary function in health and disease.

The value of air plethysmography in predicting clinical outcome after surgical treatment of chronic venous insufficiency.

PURPOSE: The role of air plethysmography (APG) as a predictor of clinical outcome after surgery in venous disease is yet to be defined. The purpose of this study was to investigate the value of APG in predicting clinical outcome after venous surgery for chronic venous insufficiency (CVI). METHODS: Seventy-three extremities in 71 patients with Class 3 through 6 CVI were assessed preoperatively with CEAP (c linical, e tiologic, a natomic, p athophysiologic) criteria, standing reflux duplex ultrasound scan, and APG with measurements of preoperative venous filling index (VFI), venous volumes, ejection fraction, and residual volume fraction. After surgical treatment of the affected limbs, repeat APG studies were obtained within 6 weeks. Established venous reporting standards were used for follow-up to calculate clinical symptom scores (CSSs) in each patient. RESULTS: Superficial venous reflux occurred alone in 24 limbs or in conjunction with perforator incompetence in 26 limbs. Deep and superficial reflux, with or without perforator incompetence, was found in 16 limbs, and seven limbs had isolated deep insufficiency. Follow-up was available in 60 of 71 patients (mean period, 44.3 months). Postoperative APG demonstrated significant hemodynamic changes after surgery as measured with VFI, venous volumes, ejection fraction, and residual volume fraction. Mean CSSs decreased from 7.35 +/- 0.56 preoperatively to 1.79 +/- 0.32 at late follow-up after surgery (P <.001). With the use of logistic regression, the parameter correlating most closely with clinical outcome was the VFI. A normal postoperative VFI (

Prospective screening for postoperative deep venous thrombosis in patients undergoing infrainguinal revascularization.

PURPOSE: The incidence of deep venous thrombosis (DVT) in patients undergoing infrainguinal bypass graft procedures has not been well documented, and the need for routine prophylaxis remains controversial. The purpose of this study was to prospectively evaluate the risk of postoperative DVT complicating infrainguinal revascularization. METHODS: Seventy-four patients undergoing infrainguinal bypass graft procedures during a 12-month period were prospectively screened for DVT. Bilateral lower extremity venous duplex scan imaging was performed preoperatively and within 1 week and 6 weeks, postoperatively. Routine DVT prophylaxis was not used, with anticoagulation reserved for specific indications. RESULTS: Of the 74 patients screened, three patients (4.1%) had DVT identified on preoperative venous duplex scan imaging and were excluded from the study. Of the remaining 71 patients enrolled, only two patients (2.8%) had postoperative DVT. Postoperative DVT was ipsilateral to the bypass graft extremity in both patients, with involvement of the peroneal vein in one patient and the femoral vein in the other. Although routine prophylaxis was not used, 18 of these patients (25%) were anticoagulated for other indications, with DVT occurring in one patient (5.6%). Of the remaining 53 patients who did not receive postoperative anticoagulation, only one patient (1.8%) had DVT. CONCLUSIONS: According to this prospective study, the risk of postoperative DVT in patients undergoing infrainguinal revascularization is low. Routine prophylaxis is not recommended, with postoperative anticoagulation reserved for specific indications.

Healing rates and cost efficacy of outpatient compression treatment for leg ulcers associated with venous insufficiency.

OBJECTIVE: Although newer techniques to promote the healing of leg ulcers associated with chronic venous insufficiency are promising, improved healing rates and cost effectiveness are unproven. We prospectively followed a series of patients who underwent treatment with outpatient compression for venous stasis ulcers without adjuvant techniques to determine healing rates and costs of treatment. METHODS: Two hundred fifty-two patients with clinical or duplex scan evidence of chronic venous insufficiency and active leg ulcers underwent treatment with ambulatory compression techniques. The patients were prospectively followed with wound measurements at 1-week to 2-week intervals, and the factors that were associated with delayed healing were determined. RESULTS: Of all the ulcers, 57% were healed at 10 weeks of treatment and 75% were healed at 16 weeks. Ultimately, 96% of the ulcers healed, and only 1 major amputation was necessitated (0.4%). Initial ulcer size and moderate arterial insufficiency (ankle brachial index, 0.5 to 0.8; n = 34) were factors that were independently associated with delayed healing (P <.01). Patient age, ulcer duration before treatment, and morbid obesity did not significantly affect healing times. The cost of 10 weeks of outpatient treatment with compression techniques ranged from $1444 to $2711. CONCLUSION: The treatment of venous stasis ulcers with compression techniques results in reliable, cost-effective healing in most patients. Current adjuvant techniques may prove to be useful but are likely to be cost effective only in a minority of cases, particularly in patients with large initial ulcer size or arterial insufficiency.

The use of near-infrared cerebral oximetry in awake carotid endarterectomy.

STUDY OBJECTIVE: To determine the utility of cerebral oximetry for monitoring the adequacy of cerebral blood flow (CBF) during carotid cross-clamp. DESIGN: Prospective study. SETTING: University hospital. PATIENTS: 16 consecutive ASA physical status III (or higher) patients for awake carotid endarterectomy (CEA). INTERVENTIONS: Regional cerebral oxygen saturation (SaO2) was monitored continuously during CEA, which was performed by the same surgeon, and with standard regional anesthetic, sedation, monitoring, and operative techniques. Data were recorded and analyzed using repeated measures analysis of variance (ANOVA). MEASUREMENTS AND MAIN RESULTS: 14 hemodynamically stable patients demonstrated significant decreases in cerebral SaO2 from baseline: 69 + 1.8% to 64 + 1.2% at carotid cross-clamp (p < 0.001). After 5, 10, and 15-minute cross-clamp time, cerebral SaO2 was 63 + 1.4%, 64 + 1.5%, and 63 + 1.4%, respectively (p < 0.001, vs. baseline). On cross-clamp removal, cerebral SaO2 rose significantly: 67 + 1.6% (p < 0.01 vs. 5, 10, and 15 min). Two hypotensive patients (mean arterial pressures of 40 and 43 mmHg) developed signs and symptoms of global cerebral ischemia, with a concomitant decrease in cerebral oximetry (40% and 48%, respectively). These changes resolved with correction of hypotension. CONCLUSION: Cerebral SaO2 decreased significantly on carotid cross-clamp in patients undergoing awake CEA. Hemodynamically stable patients demonstrated no evidence of regional brain failure when SaO2 decreased to 63% (mean decrease of 7.2%). Two hemodynamically unstable patients had evidence of global brain failure when SaO2 was less than 48% (mean decrease of 36%). Our findings suggest that cerebral oximetry reflects CBF, and it may be an effective, noninvasive method of monitoring regional cerebral oxygenation changes during CEA. Significant reductions in regional SaO2 may be tolerated without evidence of brain failure. Further studies are needed to define an SaO2 threshold that reflects regional brain failure.

Role of nitric oxide and tumor necrosis factor on lung injury caused by ischemia/reperfusion of the lower extremities.

PURPOSE: Acute aortic occlusion with subsequent ischemia/reperfusion (I/R) of the lower extremities is known to predispose to lung injury. The pathophysiologic mechanisms of this injury are not clear. In the present study, we studied the role of tumor necrosis factor (TNF) and nitric oxide (NO) in lung injury caused by lower extremity I/R. METHODS: A rat model in which the infrarenal aorta was cross-clamped for 3 hours followed by 1 hour of reperfusion was used. The rats were randomized into five groups: group 1, aorta exposed but not clamped; group 2, aorta clamped for 3 hours, followed by 1 hour of reperfusion; group 3, 1 mg/kg dexamethasone administered before the aorta was clamped; group 4, 25 mg aminoguanidine, a specific inducible NO synthase (iNOS) inhibitor, administered before the aorta was clamped; and group 5, 2 mg/kg TNFbp, a PEG-ylated dimeric form of the high-affinity p55 TNF receptor I (RI), administered before the aorta was clamped. NO concentration in the exhaled gas (ENO) was measured, as an index of NO production by the lung, in 30 minute intervals during I/R. Serial arterial blood samples for TNF assay were obtained during the course of the experiment. At the end of the experiment, the lungs were removed and histologically examined for evidence of injury. RESULTS: ENO in group 2 increased from 0.7 +/- 0.3 ppb at baseline to 54.3 +/- 7.5 ppb at the end of ischemia and remained stable during reperfusion (54.6 +/- 8.5 ppb at the end of reperfusion). ENO production was blocked by aminoguanidine, by dexamethasone, and by TNFbp given before aortic occlusion. Serum TNF in groups 2, 3 and 4 increased rapidly during early ischemia, reaching its peak value 60 minutes after occlusion of the aorta, then gradually declined to baseline levels at the end of ischemia, and remained low during reperfusion. TNFbp decreased serum TNF concentration significantly when it was given before aortic occlusion. Histologic examination of the lungs at the end of the experiment revealed that aminoguanidine, dexamethasone, and TNFbp had a protective effect on the lungs. CONCLUSIONS: Serum TNF increases rapidly during lower extremity ischemia and causes increased production of NO from the lung by upregulating iNOS. Increased NO is associated with more severe lung injury, and iNOS blockade has beneficial effects on the lung. TNF blockade before ischemia decreases NO production by the lung and attenuates lung injury. ENO can be used as an early marker of lung injury caused by lower extremity I/R.

Cardiac rupture due to blunt trauma.

Cardiac rupture due to blunt trauma has been recognized with increasing frequency over the past two decades. The mortality rate is high and the majority of patients die before they arrive at the emergency department. A high index of suspicion and prompt surgical intervention are crucial for survival. We report the management of two patients, one with a double right atrial tear and one with a single right atrial tear, after each was involved in a motor vehicle accident.

Increased nitric oxide in exhaled gas is an early marker of hypovolemic states.

Acute hemorrhage is associated with a variety of physiologic and metabolic alterations, including vascular hyporeactivity and endothelial cell dysfunction. The lung is a major target organ during hemorrhagic shock. The effect of acute hemorrhage on NO production in the lung is not well described. In the present study we examined the effect of acute hemorrhage on exhaled NO (NOe), and studied how changes in blood volume and flow affect NOe. Anesthetized and mechanically ventilated rabbits were used. The effect of acute hemorrhage by slow exsanguination on NOe was examined using chemiluminescence. Because hemorrhagic shock is associated with decreased pulmonary blood flow, we established an isolated lung preparation perfused with autologous blood (Hct = 17.4%) and studied the effect of pulmonary flow rate on NOe independent of metabolic changes. In order to separate the effect of flow from the effect of changes in blood volume, we examined the effect of flow in isolated lungs perfused with a blood-free albumin solution (PAS). In the isolated lung, ventilation was similar to that used in the intact animal, and temperature, pH, pCO2, and PO2 were kept normal. Prior to exsanguination, baseline NOe in the intact animal was 24 +/- 3 ppb. At 5, 10, 15, and 20 min after initiating the hemorrhage, NOe rose to 31 +/- 3, 51 +/- 7, 94 +/- 10, and 154 +/- 16 ppb, respectively (P < 0.05). During baseline conditions in the blood-perfused isolated lungs (200 ml/min), NOe was 35 +/- 3 ppb. When flow was decreased to 70 and 0 ml/min, NOe increased to 37 +/- 3 and 56 +/- 6 ppb, respectively (P < 0.001). During baseline conditions in the PAS-perfused lungs (70 ml/min), NOe was 94 +/- 13 ppb and was unaffected by changes in flow. The perfusion pressure in the isolated lungs was in the normal range. Reduction in blood flow rate in the isolated lung was associated with less than twofold increase in NOe. This was attributed to reduction in red blood cell volume and not due to changes in blood flow rate. Reduction in flow in the intact animal during hemorrhage generated more than threefold increase in NOe, suggesting that neurohumoral mediators, in addition to changes in flow, play an important role in determining. NOe in the intact condition. NOe began to rise immediately after exsanguination began, and therefore may be a useful early marker of acute hemorrhagic shock and hypovolemia. This information may be useful in the intensive care setting.

Objective tinnitus resulting from internal carotid artery stenosis.

Objective tinnitus represents sound wave energy that, by definition, may be heard or recorded by an examiner. It may occur as a result of either muscular contraction or turbulent blood flow. We report two cases of vascular objective tinnitus resulting from internal carotid artery stenosis. The first patient, a 74-year-old man, underwent ligation of the right internal carotid artery because of the distal extent of atherosclerosis. The second patient, a 75-year-old man, underwent a right carotid endarterectomy. Both patients noted complete relief of their tinnitus. The spectrum of vascular causes and treatment options are reviewed.

Determinants of nitric oxide in exhaled gas in the isolated rabbit lung.

Nitric oxide concentrations in the exhaled gas (NOe) increases during various inflammatory conditions in humans and animals. Little is known about the sources and factors that influence NOe. NOe at end expiration was measured by chemiluminescence in an isolated, blood-perfused rabbit lung. The average end-expiratory concentration over 10 breaths was used. The effect of positive end-expiratory pressure (PEEP), flow rate, pH, hypoxia, venous pressure, and flow pulsatility on NOe were determined. At constant blood flow, increasing PEEP from 1 to 5 cm H2O elicited a reproducible increase in NOe from 49 +/- 7 to 53 +/- 8 parts per billion (ppb) (p < 0.05). When blood pH was increased from 7.40 to 7.74 by breathing low CO2 gas, NOe rose from 45 +/- 7 to 55 +/- 7 ppb (p < 0.001). Hypoxia caused a dose-dependent decrease in NOe from 37 +/- 3 during baseline to 23 +/- 2 during ventilation with 0% O2 (p < 0.01). Venous pressure elevation from 0 to 5 and 10 mm Hg decreased NOe from 32 +/- 5, to 26 +/- 5 and 24 +/- 5 ppb, respectively (p < 0.05). Switching from steady to pulsatile flow (same man flow) resulted in a small, albeit significant reduction in NOe; 30 +/- 4 to 28 +/- 4 ppb (p < 0.05). Changes in flow rate between 200 and 20 ml/min were associated with small changes in NOe; however, when flow was stopped, NOe rose substantially to 56 +/- 6 ppb (p < 0.05). The changes in NOe were rapid (1 to 2 min) and reversible. The results suggest that NOe is influenced by ventilatory and hemodynamic variables, pH, and hypoxia. We suggest that caution must be taken when interpreting changes in exhaled NO in humans or experimental animals. Changes in total and regional blood flow, capillary blood volume, ventilation, hypoxia, and pH should not be overlooked.

Segmental pulmonary vascular responses to ATP in rat lungs: role of nitric oxide.

ATP exhibits vascular pressor and depressor responses in a dose- and tone-dependent manner. The vascular site of ATP-induced contraction or dilation has not previously been characterized. Using the vascular occlusion technique, we investigated the effects of ATP in isolated rat lungs perfused with autologous blood (hematocrit = 20%) and described its action during resting and elevated tone in terms of changes in resistances of the small and large arteries and veins. During resting tone, ATP (10(-5) M) caused contraction primarily in the small arteries and, to some extent, in the small veins, suggesting that P2x purinoceptors are present in these small vessels. During hypoxia, ATP caused dilation primarily in the small arteries, suggesting that P2y purinoceptors are predominant in small arteries. During U-46619-induced contraction, which occurred evenly throughout the four segments, ATP caused dilation in the large arteries and veins but not in the small arteries and veins. After treatment with N omega-nitro-L-arginine to inhibit nitric oxide synthesis, ATP-induced contraction was potentiated, and its dilatory effects during hypoxia were attenuated. The action of ATP was independent of prostanoids, because its constrictor and dilatory responses were not affected significantly by indomethacin. In conclusion, the results indicate that the effects of ATP on the pulmonary vasculature are primarily due to P2x and P2y purinoceptors in the small arteries. Contribution of these purinoceptors in other vessels to changes in total vascular resistance in rat lung was minor.

Characterization of monoclonal antibodies to aflatoxin M1 and molecular modeling studies of related aflatoxins.

Aflatoxin M1 (AFM1) and seven structural analogs were used to investigate the correlation between antibody binding and the conformational and electronic properties of these molecules. Mice were immunized with AFM1-BSA and hybridomas secreting anti-AFM1 antibodies were isolated and characterized. The cross-reactivities of seven structurally similar aflatoxins were determined by competition enzyme-linked immunosorbent assay (cELISA). In an effort to correlate antibody binding with three-dimensional properties of the analogs, all of the aflatoxins (and the immunogen) were modeled and global energy minima were determined using molecular, mechanical and quantum mechanical methods. The results demonstrate that, for these molecules, loss of optimum structure and introduction of steric hindrance in the portion of the molecule that would fit into the antibody binding site are more important to binding than simply loss of a determinant group. Molecular computational techniques can give reasons for the wide variation in IC50 values observed between structural analogs and can be used as a tool for determining which conformational and electronic properties of molecules are most important for antibody binding.