Enhancement of gemcitabine cytotoxicity in pancreatic adenocarcinoma through controlled release of nitric oxide.

Gemcitabine (GEM) is the first-line treatment for pancreatic adenocarcinoma (PAC) yet chemoresistance is common. Nitric oxide (NO) is the predominant species responsible for the cytotoxic action of macrophages against cancer cells yet localized delivery is difficult given the short half-life. We sought to study the effect of locally delivered NO on GEM mediated PAC cytotoxicity and the potential role of SMAD4 in this effect. We hypothesized that NO would enhance the cytotoxicity of GEM in a SMAD4 dependent manner. NO-Silica nanoparticles (NO-Si) were synthesized via a co-condensation of tetraethoxysilane with aminoalkoxysilane under high-pressure nitrous oxide. NO release was measured using chemiluminescence. A SMAD4 negative PAC cell line (SMAD4-) was made using retroviral knockdown of Panc1 PAC cells. Panc1 and SMAD4- cells were treated with gemcitabine (100 nm (hi) to 30 µm (lo)), 30 mg NOSi particles, or both (NOSihi or NOSilo) and cell viability assessed. NoSi reduced cell viability by 25.99% in Panc1 and 24.38% in SMAD4-. When combined with gemcitabine, further reductions were seen in a dose dependent manner for both cell lines. We have demonstrated the in-vitro dose dependent cytotoxic effects of NOSi. When combined with GEM there is a synergistic effect resulting in improved cytotoxicity seen in both Panc1 and SMAD4- PAC cells with a differential pattern of cell death seen at high concentrations of NO. These findings suggest not only that NO is useful chemosensitizing agent but that SMAD4- may play a role in its synergism with GEM.

Mass release curves as the constitutive curves for modeling diffusive transport within biological tissue.

In diffusion governed by Fick's law, the diffusion coefficient represents the phenomenological material parameter and is, in general, a constant. In certain cases of diffusion through porous media, the diffusion coefficient can be variable (i.e. non-constant) due to the complex process of solute displacements within microstructure, since these displacements depend on porosity, internal microstructural geometry, size of the transported particles, chemical nature, and physical interactions between the diffusing substance and the microstructural surroundings. In order to provide a simple and general approach of determining the diffusion coefficient for diffusion through porous media, we have introduced mass release curves as the constitutive curves of diffusion. The mass release curve for a selected direction represents cumulative mass (per surface area) passed in that direction through a small reference volume, in terms of time. We have developed a methodology, based on numerical Finite Element (FE) and Molecular Dynamics (MD) methods, to determine simple mass release curves of solutes through complex media from which we calculate the diffusion coefficient. The diffusion models take into account interactions between solute particles and microstructural surfaces, as well as hydrophobicity (partitioning). We illustrate the effectiveness of our approach on several examples of complex composite media, including an imaging-based analysis of diffusion through pancreatic cancer tissue. The presented work offers an insight into the role of mass release curves in describing diffusion through porous media in general, and further in case of complex composite media such as biological tissue.

A composite smeared finite element for mass transport in capillary systems and biological tissue.

One of the key processes in living organisms is mass transport occurring from blood vessels to tissues for supplying tissues with oxygen, nutrients, drugs, immune cells, and - in the reverse direction - transport of waste products of cell metabolism to blood vessels. The mass exchange from blood vessels to tissue and vice versa occurs through blood vessel walls. This vital process has been investigated experimentally over centuries, and also in the last decades by the use of computational methods. Due to geometrical and functional complexity and heterogeneity of capillary systems, it is however not feasible to model in silico individual capillaries (including transport through the walls and coupling to tissue) within whole organ models. Hence, there is a need for simplified and robust computational models that address mass transport in capillary-tissue systems. We here introduce a smeared modeling concept for gradient-driven mass transport and formulate a new composite smeared finite element (CSFE). The transport from capillary system is first smeared to continuous mass sources within tissue, under the assumption of uniform concentration within capillaries. Here, the fundamental relation between capillary surface area and volumetric fraction is derived as the basis for modeling transport through capillary walls. Further, we formulate the CSFE which relies on the transformation of the one-dimensional (1D) constitutive relations (for transport within capillaries) into the continuum form expressed by Darcy's and diffusion tensors. The introduced CSFE is composed of two volumetric parts - capillary and tissue domains, and has four nodal degrees of freedom (DOF): pressure and concentration for each of the two domains. The domains are coupled by connectivity elements at each node. The fictitious connectivity elements take into account the surface area of capillary walls which belongs to each node, as well as the wall material properties (permeability and partitioning). The overall FE model contains geometrical and material characteristics of the entire capillary-tissue system, with physiologically measurable parameters assigned to each FE node within the model. The smeared concept is implemented into our implicit-iterative FE scheme and into FE package PAK. The first three examples illustrate accuracy of the CSFE element, while the liver and pancreas models demonstrate robustness of the introduced methodology and its applicability to real physiological conditions.

Prolonged exposure to extracellular lumican restrains pancreatic adenocarcinoma growth.

We previously demonstrated that pancreatic stellate cells within pancreatic ductal adenocarcinoma (PDAC) stroma secrete lumican and its presence is associated with prolonged survival of patients with localized PDAC. Here, we observed that extracellular lumican decreases PDAC tumour cell growth in xenograft and syngeneic orthotopic animal models, and induces growth inhibition of low-passage human PDAC cells in a species-specific manner. PDAC cells grown in variant culture conditions and exposed to extracellular lumican display typical characterizations of cancer cell in a quiescent state, such as growth inhibition, apoptosis, G0/G1 arrest and chemoresistance. Importantly, extracellular lumican is associated with diminished ERK1/2 phosphorylation and increased p38 phosphorylation within PDAC cells. We further demonstrated that extracellular lumican physically binds with EGFR to trigger EGFR internalization and downregulation of EGFR and its downstream signal molecule ERK. Lumican enhances casitas B-lineage lymphoma expression, which stabilized the TGFß Type II receptor sensitizing PDAC cells to TGFß-mediated activation of p38 and SMAD signals. These provide a mechanism for the shift in signalling and phenotypic changes we observed after prolonged exposure to lumican. Together, our findings demonstrate that stromal lumican restrains PDAC cell growth through mediating cell entry into a quiescent state.

Extracellular lumican augments cytotoxicity of chemotherapy in pancreatic ductal adenocarcinoma cells via autophagy inhibition.

Lumican, an extracellular matrix proteoglycan overexpressed by pancreatic stellate cells (PSCs) and pancreatic ductal adenocarcinoma cells (PDACs), drives the formation of a tumor-specific microenvironment. We recently showed that extracellular lumican inhibits pancreatic cancer cell growth and is associated with prolonged survival after surgery. Here we investigated the role of extracellular lumican in chemotherapy-mediated cancer therapy. Lumican secretion was increased by chemotherapeutic agents in PDAC, and especially in PSCs, and appeared to be linked to the extent of cells' response to chemotherapy-induced growth inhibition. In multiple PDAC models, including cell lines, patient-derived xenografts and lumican knockout mice, lumican significantly increased antitumor effect of chemotherapy. This effect was associated with DNA damage, apoptosis and inhibition of cell viability, glucose consumption, lactate production and vascular endothelial growth factor secretion. In PDAC cells, chemotherapeutic agents triggered autophagosome formation and increased LC3 expression through the reactive oxygen species-mediated AMP-activated kinase (AMPK) signaling pathway. Inhibition of gemcitabine-induced autophagy in cancer cells by treatment with AMPK inhibitor compound C, lysosomal inhibitor chloroquine or autophagy inhibitor 3MA enhanced gemcitabine-induced apoptosis, suggesting that autophagy is a protective cellular response to gemcitabine treatment. Importantly, lumican dramatically decreased AMPK activity, inhibiting chemotherapy-induced autophagy in both in vitro and in vivo PDAC models. Co-treatment of PDAC cells with lumican and gemcitabine increased mitochondrial damage, reactive oxygen species (ROS) production and cytochrome c release, indicating that lumican-induced disruption of mitochondrial function may be the mechanism of sensitization to gemcitabine. Together, our findings demonstrate that extracellular lumican augments cytotoxicity of chemotherapy in PDAC cells through inhibition of chemotherapeutic agent-induced autophagy.

Color-coding cancer and stromal cells with genetic reporters in a patient-derived orthotopic xenograft (PDOX) model of pancreatic cancer enhances fluorescence-guided surgery.

Precise fluorescence-guided surgery (FGS) for pancreatic cancer has the potential to greatly improve the outcome in this recalcitrant disease. To achieve this goal, we have used genetic reporters to color code cancer and stroma cells in a patient-derived orthotopic xenograft (PDOX) model. The telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 was used to label the cancer cells of a pancreatic cancer PDOX. The PDOX was previously grown in a red fluorescent protein (RFP) transgenic mouse that stably labeled the PDOX stroma cells bright red. The color-coded PDOX model enabled FGS to completely resect the pancreatic tumors including stroma. Dual-colored FGS significantly prevented local recurrence, which bright-light surgery or single-color FGS could not. FGS, with color-coded cancer and stroma cells has important potential for improving the outcome of recalcitrant-cancer surgery.

CT imaging features of acinar cell carcinoma and its hepatic metastases.

OBJECTIVE: To evaluate and describe the computed tomography features of pure acinar cell carcinoma (ACC) and its liver metastases. METHODS: Thirty patients were evaluated. Two radiologists evaluated imaging findings for each tumor for size, location, internal density, enhancement, tumor calcifications, pancreatic, and common biliary ductal obstructions and metastases. RESULTS: 70 % were male. Fourteen tumors were located in the pancreatic head, 14 in the tail, one in the neck, and one in the uncinate process. Abdominal pain was the most common presenting symptom (93 %), 20 % had pancreatitis and 17 % had obstructive jaundice. The average tumor size was 7 cm, 97 % of tumors were solid, well circumscribed (73 %); isodense to normal pancreatic parenchyma (40 %) on the non-contrast study, hypodense on the arterial (47 %), and hypodense on the portal venous (37 %) phase. 30 % patients had pancreatic ductal dilation, 10 % had pancreatic ductal ingrowth, 6 % had calcifications, and 20 % had central necrosis, and 31 % (5/16) showed biliary ductal dilation. At presentation, 50 % had metastatic adenopathy and 40 % patients had liver metastases, which typically were well circumscribed, hypoattenuating to the hepatic parenchyma on all the phases of contrast enhancement and had a lobulated margin. CONCLUSION: ACCs of the pancreas often present as large, well circumscribed, solid masses commonly in males. Despite their large size, they may not cause CBD obstruction.

The integration of chemoradiation in the care of patient with localized pancreatic cancer.

The use of chemoradiation for patients with localized pancreatic cancer is controversial. Although some randomized trials have indicated that chemoradiation improves the median survival of patients with locally advanced as well as resected pancreatic cancer, other more recent trials have called into question the role of chemoradiation and have supported the use of chemotherapy. In the adjuvant setting, the high local tumor recurrence/persistence rate in all trials probably reflects the inclusion of patients with incompletely resected tumors, whose prognosis is similar to the prognosis of patients with locally advanced who do not undergo resection, making these trials difficult to interpret. More precise clinical staging and selection of patients appropriate for surgical resection is an important goal. The keys to the successful integration of radiotherapy in the care of patients with localized pancreatic cancer are selection, sequencing and smaller treatment volumes. A strategy of initial chemotherapy followed by consolidation with a well-tolerated chemoradiation regimen both in the adjuvant and locally advanced settings maximizes benefits of both treatment options, which are in fact complementary. Herein, we discuss the rationale for this approach as well as the ongoing investigation of novel radiation approaches designed to enhance outcome through the molecular and physical targeting of disease as well as the investigation of neoadjuvant chemoradiation in radiographically resectable and borderline resectable pancreatic cancer.

Sentinel lymph node biopsy identifies occult nodal metastases in patients with Marjolin's ulcer.

Since Marjolin's description, the management of burn scar carcinoma has remained controversial. A multitude of options and recommendations exist for the management of both primary lesions and regional nodal metastasis. This work reviews six cases of Marjolin's ulcer staged using sentinel lymph node biopsy. All primary lesions were confirmed to be squamous cell carcinoma and occurred a median of 29.5 years after burn. No patient had clinically detectable lymphadenopathy. In all cases, preoperative lymphoscintigraphy successfully identified a single draining regional nodal basin. Subsequent intraoperative lymphatic mapping/sentinel lymph node (SLN) biopsy was successful in five of six cases (83%). A successful intraoperative lymphatic mapping/SLN biopsy was defined as the identification of blue (uptake of isosulfan blue dye) or "hot" (uptake of radiolabeled sulfur colloid as measured with a handheld gamma counter) node(s) and subsequent excision. Four of five SLN biopsies identified previously occult nodal metastasis. SLN biopsy represents a minimally invasive and accurate staging procedure for Marjolin's ulcer.

Laparoscopy alone is superior to peritoneal cytology in staging gastric and esophageal carcinoma.

BACKGROUND: Laparoscopy identifies metastatic disease in patients with upper gastrointestinal malignancies; however, it has been suggested that cytological examination of peritoneal washings may increase the diagnostic yield. We hypothesize that the addition of cytologic washings to a standardized staging laparoscopy is unnecessary for the identification of intraabdominal metastasis in patients with gastric/esophageal cancer. METHODS: Forty patients with gastric/esophageal cancer were prospectively evaluated. Patients successfully underwent a diagnostic laparoscopy protocol (with biopsies) during which peritoneal washings were obtained and processed for cytologic analysis. Laparoscopic versus cytologic identification of intraabdominal metastasis were compared. RESULTS: Forty patients successfully completed laparoscopy with collection of peritoneal washings. Laparoscopic examination of the peritoneal cavity upstaged 21 (52.5%) patients. Laparoscopic examination consistently identified a statistically significant higher number of positive patients than cytologic examination of peritoneal washings (p = 0.001) and examination of cytologic washings alone failed to identify 45% of patients with positive findings and laparoscopy. The addition of cytologic examination added no additional stage IV patients to the laparoscopy-negative group. CONCLUSION: A standardized laparoscopic examination alone is sufficient for the identification of intraabdominal metastatic disease in patients with gastric and esophageal cancer.

The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors.

BACKGROUND: The purpose of this study was to determine the effect of hepatic inflow occlusion (the Pringle maneuver) on laparoscopic radiofrequency (RF) ablation. METHODS: Using a previously validated agarose tissue-mimic model, 1-cm simulated hepatic tumors (three per animal) were laparoscopically ablated in five pigs with normal perfusion and then in five pigs with hepatic artery and portal vein occlusion. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for eight min. Specimens were examined immediately after treatment. RESULTS: Vascular occlusion was successful in all cases per color-flow Doppler ultrasound. Pringle time was 11.4 +/- 1.6 min. Warm-up time (2.7 +/- 1.4 vs 20.2 +/- 14.0 min) was significantly faster in the Pringle group. Ablation diameter (34.8 +/- 2.9 vs 24.7 +/- 3.1 mm), proportion of round/ovoid lesions (93% vs 20%), ablation symmetry (100% vs 40%), and margin distance (5.1 +/- 3.0 vs 1.1 +/- 1.2 mm) were significantly better for the Pringle group than the No Pringle group, respectively. CONCLUSION: Using a Pringle maneuver during laparoscopic RF ablation significantly enhances ablation geometry and results in larger margins.

Comparison of video trainer and virtual reality training systems on acquisition of laparoscopic skills.

Training on a video trainer or computer-based minimally invasive surgery trainer leads to improved benchtop laparoscopic skill. Recently, improved operative performance from practice on a video trainer was reported. The purpose of this study was three fold: (a) to compare psychomotor skill improvement after training on a virtual reality (VR) system with that after training on a video-trainer, (VT) (b) to evaluate whether skills learned on the one training system are transferable to the other, and (c) to evaluate whether VR or VT training improves operative performance. For the study, 50 junior surgery residents completed baseline skill testing on both the VR and VT systems. These subjects then were randomized to either a VR or VT structured training group. After practice, the subjects were tested again on their VR and VT skills. To assess the effect of practice on operative performance, all second-year residents (n = 19) were evaluated on their operative performance during a laparoscopic cholecystectomy before and after skill training. Data are expressed as percentage of improvement in mean score/time. Analysis was performed by Student's paired t-test. The VR training group showed improvement of 54% on the VR posttest, as compared with 55% improvement by the VT group. The VR training group improved more on the VT posttest tasks (36%) than the VT training group improved on the VR posttest tasks (17%) (p <0.05). Operative performance improved only in the VR training group (p <0.05). Psychomotor skills improve after training on both VR and VT, and skills may be transferable. Furthermore, training on a minimally invasive surgery trainer, virtual reality system may improve operative performance during laparoscopic cholecystectomy.

Utility of chest computed tomography for staging in patients with T1 extremity soft tissue sarcomas.

BACKGROUND: National Cancer Center Network (NCCN) and Society of Surgical Oncology (SSO) practice guidelines recommend chest computed tomography (CT) as part of the staging evaluation of patients with extremity soft tissue sarcoma (STS). In the current study, the authors evaluated the use and yield of chest roentgenography (CXR) and selective chest CT to screen for pulmonary metastases in patients with T1 STS. METHODS: The utility of these staging studies was evaluated retrospectively in a cohort of 125 consecutive patients who presented to a tertiary care cancer center with T1 primary (nonrecurrent) extremity STS. Two diagnostic strategies (CXR alone vs. CXR plus chest CT) were evaluated using an incremental cost-effectiveness ratio. RESULTS: The majority of tumors (70%) were high grade. The median sarcoma size was 3.0 cm; 64 of the tumors (51%) were located deep to the investing fascia of the extremity. All patients underwent staging CXR; 1 CXR (< 1%) was suspicious for metastatic disease. Fifty-one patients (41%) also underwent chest CT; 1 chest CT, performed in the patient with a suspicious CXR, revealed metastatic disease. With a median follow-up of 76 months, 19 patients (15%) developed metachronous pulmonary metastases. The relatively low yield resulted in an incremental cost-effectiveness ratio of $59,772 per case of synchronous pulmonary metastasis detected by CXR plus chest CT. CONCLUSIONS: Less than 1% of patients with T1 primary extremity STS were found to have pulmonary metastases that were detectable using a staging algorithm that employs routine CXR with the selective use of chest CT. The findings of the current study do not support current NCCN or SSO practice guidelines for patients with high-grade T1 STS.

Accuracy and effectiveness of laparoscopic vs open hepatic radiofrequency ablation.

BACKGROUND: The purpose of this study was to compare the accuracy (in terms of ultrasound-guided probe placement) and the effectiveness (in terms of pathologic tumor-free margin) of laparoscopic vs open radiofrequency (RF) ablation. METHODS: Using a previously validated tissue-mimic model, 1-cm simulated hepatic tumors were ablated in 10 pigs randomized to open or laparoscopic techniques. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for 8 min. A pathologist blinded to technique examined all specimens immediately after treatment. Analysis was by Fisher's exact test and the Mann-Whitney U test; p < 0.05 was considered significant. RESULTS: Off-center distance (3.5 +/- 1.6 vs 4.2 +/- 1.4 mm), size (24.7 +/- 3.1 vs 25.6 +/- 3.8 mm), symmetry (40% vs 73%), margin positivity (33% vs 9%), and margin distance (1.1 +/- 1.2 vs 2.2 +/- 1.6 mm) were not significantly different between laparoscopic (n = 15) and open (n = 11) ablations, respectively. The proportion of round/ovoid lesions (20% vs 64%) was lower (p = 0.043), and warm-up time (20.2 +/- 14.0 vs 10.7 +/- 7.5) was longer (p = 0.049) for the laparoscopic than for the open groups, respectively. CONCLUSION: Accurate probe placement can be achieved using laparoscopic and open RF ablation techniques. The physiologic effects of laparoscopy may alter ablation shape and warm-up time. Additional studies are needed to establish effective ways of achieving complete tumor destruction.

Endothelin-1 enhances eicosanoids-induced coronary smooth muscle contraction by activating specific protein kinase C isoforms.

Endothelin-1 (ET-1), a potent vasoconstrictor, has been implicated in the pathogenesis of coronary vasospasm by enhancing coronary vasoconstriction to vasoactive eicosanoids; however, the cellular mechanisms involved are unclear. We investigated whether physiological concentrations of ET-1 enhance coronary smooth muscle contraction to vasoactive eicosanoids by activating specific protein kinase C (PKC) isoforms. Cell contraction was measured in single smooth muscle cells isolated from porcine coronary arteries, intracellular free Ca(2+) ([Ca(2+)](i)) was measured in fura-2-loaded cells, and the cytosolic and particulate fractions were examined for PKC activity and reactivity with isoform-specific anti-PKC antibodies using Western blots. In Hanks' solution (1 mmol/L Ca(2+)), ET-1 (10 pmol/L) did not increase basal [Ca(2+)](i) (81+/-2 nmol/L), but it did cause cell contraction (9%) that was inhibited by GF109203X (10(-6) mol/L), an inhibitor of Ca(2+)-dependent and Ca(2+)-indpendent PKC isoforms. The vasoactive eicosanoid prostaglandin F(2alpha) (PGF(2alpha), 10(-7) mol/L) caused increases in cell contraction (11%) and [Ca(2+)](i) (108+/-7 nmol/L) that were inhibited by the Ca(2+) channel blocker diltiazem (10(-6) mol/L). Pretreatment with ET-1 (10 pmol/L) for 10 minutes enhanced cell contraction to PGF(2alpha) (35%) with no additional increase in [Ca(2+)](i) (112+/-8 nmol/L). Direct activation of PKC by phorbol 12,13-dibutyrate (PDBu, 10(-7) mol/L) caused cell contraction (10%) and enhanced PGF(2alpha) contraction (33%) with no additional increase in [Ca(2+)](i) (115+/-7 nmol/L). The ET-1-induced enhancement of PGF(2alpha) contraction was inhibited by Gö6976 (10(-6) mol/L), an inhibitor of Ca(2+)-dependent PKC isoforms. Both ET-1 and PDBu caused an increase in PKC activity in the particulate fraction and a decrease in the cytosolic fraction and increased the particulate/cytosolic PKC activity ratio. Western blots revealed the Ca(2+)-dependent alpha-PKC and the Ca(2+)-independent delta-, epsilon-, and zeta-PKC isoforms. In resting tissues, alpha- and epsilon-PKC were mainly cytosolic, delta-PKC was mainly in the particulate fraction, and zeta-PKC was equally distributed in the cytosolic and particulate fraction. ET-1 (10 pmol/L) alone or PDBu (10(-7) mol/L) alone caused translocation of epsilon-PKC from the cytosolic to the particulate fraction, localized delta-PKC more in the particulate fraction, but did not change the distribution of zeta-PKC. PGF(2alpha) (10(-7) mol/L) alone did not change PKC activity. In tissues pretreated with ET-1 or PDBu, PGF(2alpha) caused additional increases in alpha-PKC activity. Thus, the enhancement of PGF(2alpha)-induced coronary smooth muscle contraction by physiological concentrations of ET-1 involves activation and translocation of alpha-PKC in addition to delta- and epsilon-PKC isoforms, and this may represent one possible cellular mechanism by which ET-1 could enhance coronary vasoconstriction to vasoactive eicosanoids in coronary vasospasm.

[Ca(2+)](i) signaling in renal arterial smooth muscle cells of pregnant rat is enhanced during inhibition of NOS.

Vascular resistance and arterial pressure are reduced during normal pregnancy, but dangerously elevated during pregnancy-induced hypertension (PIH), and changes in nitric oxide (NO) synthesis have been hypothesized as one potential cause. In support of this hypothesis, chronic inhibition of NO synthesis in pregnant rats has been shown to cause significant increases in renal vascular resistance and hypertension; however, the cellular mechanisms involved are unclear. We tested the hypothesis that the pregnancy-associated changes in renal vascular resistance reflect changes in contractility and intracellular Ca(2+) concentration ([Ca(2+)](i)) of renal arterial smooth muscle. Smooth muscle cells were isolated from renal interlobular arteries of virgin and pregnant Sprague-Dawley rats untreated or treated with the NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME; 4 mg. kg(-1). day(-1) for 5 days), then loaded with fura 2. In cells of virgin rats incubated in Hanks' solution (1 mM Ca(2+)), the basal [Ca(2+)](i) was 86 +/- 6 nM. Phenylephrine (Phe, 10(-5) M) caused a transient increase in [Ca(2+)](i) to 417 +/- 11 nM and maintained an increase to 183 +/- 8 nM and 32 +/- 3% cell contraction. Membrane depolarization by 51 mM KCl, which stimulates Ca(2+) entry from the extracellular space, caused maintained increase in [Ca(2+)](i) to 292 +/- 12 nM and 31 +/- 2% contraction. The maintained Phe- and KCl-induced [Ca(2+)](i) and contractions were reduced in pregnant rats but significantly enhanced in pregnant rats treated with L-NAME. Phe- and KCl-induced contraction and [Ca(2+)](i) were not significantly different between untreated and L-NAME-treated virgin rats or between untreated and L-NAME + L-arginine treated pregnant rats. In Ca(2+)-free Hanks', application of Phe or caffeine (10 mM), to stimulate Ca(2+) release from the intracellular stores, caused a transient increase in [Ca(2+)](i) and a small cell contraction that were not significantly different among the different groups. Thus renal interlobular smooth muscle of normal pregnant rats exhibits reduction in [Ca(2+)](i) signaling that involves Ca(2+) entry from the extracellular space but not Ca(2+) release from the intracellular stores. The reduced renal smooth muscle cell contraction and [Ca(2+)](i) in pregnant rats may explain the decreased renal vascular resistance associated with normal pregnancy, whereas the enhanced cell contraction and [Ca(2+)](i) during inhibition of NO synthesis in pregnant rats may, in part, explain the increased renal vascular resistance associated with PIH.

Sentinel lymph node biopsy is accurate after neoadjuvant chemotherapy for breast cancer.

PURPOSE: Sentinel lymph node (SLN) biopsy has proved to be an accurate method for detecting nodal micrometastases in previously untreated patients with early-stage breast cancer. We investigated the accuracy of this technique for patients with more advanced breast cancer after neoadjuvant chemotherapy. PATIENTS AND METHODS: Patients with stage II or III breast cancer who had undergone doxorubicin-based neoadjuvant chemotherapy before breast surgery were eligible. Intraoperative lymphatic mapping was performed with peritumoral injections of blue dye alone or in combination with technetium-labeled sulfur colloid. All patients were offered axillary lymph node dissection. Negative sentinel and axillary nodes were subjected to additional processing with serial step sectioning and immunohistochemical staining with an anticytokeratin antibody to detect micrometastases. RESULTS: Fifty-one patients underwent SLN biopsy after neoadjuvant chemotherapy from 1994 to 1999. The SLN identification rate improved from 64.7% to 94.1%. Twenty-two (51.2%) of the 43 successfully mapped patients had positive SLNs, and in 10 of those 22 patients (45.5%), the SLN was the only positive node. Three patients had false-negative SLN biopsy; that is, the sentinel node was negative, but at least one nonsentinel node contained metastases. Additional processing revealed occult micrometastases in four patients (three in sentinel nodes and one in a nonsentinel node). CONCLUSION: SLN biopsy is accurate after neoadjuvant chemotherapy. The SLN identification improved with experience. False-negative findings occurred at a low rate throughout the series. This technique is a potential way to guide the axillary treatment of patients who are clinically node negative after neoadjuvant chemotherapy.

Development of an in vivo tumor-mimic model for learning radiofrequency ablation.

Radiofrequency ablation requires accurate probe placement using ultrasound guidance. The purpose of this study was to develop an in vivo tumor-mimic model for learning open and laparoscopic radiofrequency ablation. Tumor-mimics were created in ex vivo porcine livers by injecting a mixture of 3% agarose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, which formed 1 cm hyperechoic, discrete lesions on ultrasound. Open and laparoscopic (using a box-trainer) ablation techniques were practiced. In vivo experiments were then conducted in 10 pigs. Three tumor-mimics were created in each animal using a laparoscopic approach. Lesions were characterized sonographically, ablated using an open (n = 5) or laparoscopic (n = 5) approach, and examined pathologically. An ablation in normal liver tissue was performed as a control. Tissue impedance was recorded. Target creation took 81 minutes per animal and 96% of injections were successful. Tissue impedance (48.8 +/- 5.8 vs. 49.6 +/- 5.4) and ablation size (25.1 +/- 3.4 vs. 24.3 +/- 5.1) were not significantly different for controls (n = 8) and tumor-mimics (n = 26), respectively. One animal died of a pulmonary embolism following injection of agarose into a hepatic vein. The agarose-based tissue-mimic creates realistic sonographic targets for learning ultrasound-guided open and laparoscopic radiofrequency ablation in an in vivo model.

Clinical description and review of migraine aura without headache.

BACKGROUND: Migraine aura without headache (MAWOH) is a type of migraine that seems to be reported more frequently in ophthalmic than neurologic or general medical practice. The clinical characteristics of this condition are described relative to its relationship with other forms of migraine, patient age, gender distribution, laterality, personal or family history, visual aura, and precipitating factors. As a result of its prevalence, it is a condition with which every optometrist and ophthalmologist should be familiar. Since MAWOH is a common cause of photopsia and transient vision loss, it is also important to consider it in the differential diagnosis of these conditions-especially in older patients. METHODS: The clinical investigations of MAWOH by prospective and retrospective case series are reviewed. This review includes an analysis by study of the number of patients, migraine history, and type of visual symptom. Comparison of clinical characteristics is used to distinguish MAWOH from other types of migraine. CONCLUSION: Migraine aura without headache is a type of migraine that is reported frequently in ophthalmic practice. Because it is related to photopsia and/or transient vision loss, specific clinical procedures should be performed to assist in the differential diagnosis of these conditions.