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Biomedical subjects

S R Evans

Publications and source records attributed to S R Evans.

68 records · Page 4Linked to original sources
PubMed1992

Intraoperative bile duct sonography during laparoscopic cholecystectomy: experience with a 12.5-MHz catheter-based US probe.

During elective laparoscopic cholecystectomy, 20 patients underwent intraoperative evaluation of the biliary tract with a commercial 6.2-F, 12.5-MHz catheter-based ultrasound (US) probe. The study tested the feasibility of this technology for mapping the anatomy of the hepatoduodenal ligament and Calot triangle, assessing bile duct integrity, and detecting choledocholithiasis. The duct was studied with a transmural approach, the catheter being placed parallel to, but remaining outside, the bile duct. The common hepatic duct and common bile duct in the vicinity of the cystic duct were seen in all 20 patients; the junction of the cystic duct with the common hepatic duct was seen in nine patients (45%). After the cystic duct was clamped, no sonographic evidence to suggest bile duct injury was noted in any patient. The transmural imaging approach was tested in four pigs in whose common bile duct a single human calculus had been placed. In all instances the size and location of the calculus were accurately detected. Intraoperative US with a catheter-based system is a safe and effective means for interrogation of the extrahepatic biliary tree during laparoscopic cholecystectomy.

Adult↗
PubMed1992

An unusual case of intermittent venous obstruction of the upper extremity.

The axillary vein can be subject to intermittent obstruction from numerous anatomic structures such as the pectoralis minor and the scalenus anterior muscles. The diagnosis can be readily made on history and physical examination of the upper extremity, but it can be difficult to confirm by routine venogram done with the arm in the standard position at the side with full extension at the antecubital fossa. Positional venography with the arm fully abducted and flexion of that antecubital fossa allows for better definition of this extrinsic compression. In the case presented, a fascial band arising from the medial head of the biceps was compressing the axillary vein and was suspected on history and physical examination; it was confirmed with positional venography as noted. As in this case, it is important to make the diagnosis early, before thrombosis of the vein occurs, to minimize the associated morbidity. Transaxillary exploration was performed with excision of the band and complete resolution of the symptoms. Subsequent noninvasive studies were performed that showed complete resolution of the extrinsic axillary vein compression. Having a high suspicion of intermittent venous obstruction with early diagnosis and surgical correction of any extrinsic compression are the keys to a successful outcome in these patients.

Adult↗
PubMed1990

Comparative field evaluation of permethrin and deet-treated military uniforms for personal protection against ticks (Acari).

The effectiveness of permethrin-impregnated (PI) versus permethrin-sprayed (PS) military battle dress uniforms was evaluated in protecting soldiers from tick bite. At the same time, an extended-duration formulation of N,N-diethyl-m-toluamide (deet), when applied to clothing only, was evaluated and compared with the permethrin-treated uniforms. Testing consisted of exposing subjects, clothed in either untreated or the variously treated uniforms, to field populations of ticks during a series of 30-min field trials over a period of 21 d during July and August 1988. Permethrin, applied as either a spray (0.5% [AI]), or as an impregnant (0.125% [AI]/cm2), was more effective than deet (33.25% [AI]) applied to clothing only in protecting individuals from tick bite. The mean numbers of ticks on deet-treated, PI, and PS uniforms were 60, 97, and 98% lower, respectively, than on untreated uniforms against all encountered life stages of Amblyomma americanum (L), Dermacentor variabilis (Say), and Ixodes dammini Spielman, Clifford, Piesman and Corwin.

Animals↗
PubMed1989

Intraperitoneal chemotherapy complicated by erosion of a Tenckhoff catheter into the colon.

Insertion and maintenance of intraperitoneal catheters must be done with meticulous attention to detail. We recommend insertion under direct vision to minimize the incidence of intestinal perforation during catheter placement. Intraperitoneal catheters should not be placed in close proximity to a fresh intestinal anastomosis because this position may promote anastomotic dehiscence. Communication between the catheter and the intestinal lumen necessitates catheter removal.

Catheters, Indwelling↗
PubMedDate not supplied

Palliative superselective intra-arterial chemotherapy for advanced nonresectable gastric cancer.

From November 1988 to May 1996, a prospective randomized study was undertaken to assess the efficacy of superselective intra-arterial chemotherapy for surgically proved unresectable gastric carcinoma. Each patient had undergone endoscopy as well as abdominal and pelvic CT scanning for staging. Patients with evidence of liver metastasis, peritoneal carcinomatosis, enlarged retroperitoneal lymph nodes, or locally advanced disease beyond curative resection were excluded from the study. A total of 386 patients with potentially curable disease were randomized to one of three treatment groups: (1) control; (2) systemic intravenous chemotherapy; or (3) superselective intra-arterial chemotherapy. On completion of preoperative chemotherapy, all patients underwent operative exploration with curative intent. A total of 74 consecutive patients were found to be unresectable, as evidenced by the presence of liver metastasis, peritoneal carcinomatosis, enlarged retroperitoneal lymph nodes, or locally extensive disease not detected by preoperative CT scanning. The median survival time in the control group and after intravenous chemotherapy was only 91 and 96 days, respectively, as compared to 401 days in the patients receiving intra-arterial chemotherapy. The results confirmed that superselective intra-arterial chemotherapy conferred a highly significant survival advantage compared to control or systemic intravenous chemotherapy adjusted for all patient characteristics (P <0.0001).

Adult↗
PubMedDate not supplied

In vitro effect of 5-fluorouracil, verapamil and hyperthermia on the human pancreatic adenocarcinoma cell line ASPC-1.

The purpose of this study was to assess the efficacy of verapamil (20 microM) and hyperthermia (42 degrees C) as modifiers of 5-fluorouracil (5-FU) used at different concentrations, in inhibiting the growth of human pancreatic adenocarcinoma cells. Combined verapamil and hyperthermia treatment significantly decreased cell count by 63.8% when compared to the control. Verapamil drastically enhanced the growth inhibitory effect of 5-FU at all concentrations. At high-concentration 5-FU (50 micrograms/ml), verapamil and hyperthermia had a synergistic growth-inhibitory effect and caused a significant decrease in cell count by 81.4% in comparison to the control. The modalities analyzed in this study require further investigation and have potential for clinical applicability to pancreatic cancer therapy in the future.

Adenocarcinoma↗
PubMedDate not supplied

Apoptosis induced by hyperthermia and verapamil in vitro in a human colon cancer cell line.

The aim of this study was to determine the mechanisms responsible for the growth inhibitory effect of hyperthermia and verapamil in human colon cancer cell line HT-29. Apoptotic cell death was verified by flow cytometry analysis. The effect of treatment with hyperthermia and verapamil on the expression of apoptosis-associated proteins including Bcl-2, p53, bax, and c-Myc was studied by Western blot analysis. Changes in intracellular calcium homeostasis was analysed by fluorescence microscopy. The combination of 42 degrees C hyperthermia and verapamil caused a significant delay of human colon cancer cell proliferation as a result of apoptosis. Administration of these agents alone did not cause any cell inhibitory effect. Our experiments have shown that HT-29 cells constitutively express apoptosis-promoting proteins, such as Bax and c-Myc, while they fail to produce Bcl-2. Therefore, we hypothesize that HT-29 cells must have Bcl-2 independent pathways to protect cells against death-inducing signals. Also, apoptosis of HT-29 cells produced by hyperthermia in the presence of verapamil is a p53-independent process. Verapamil, when it did not act as a calcium channel blocker or inhibitor of release from intracellular storages under hyperthermic conditions, accelerated the increase of [Ca2+]i in HT-29 cells which resulted in programmed cell death (apoptosis).

Apoptosis↗
PubMedDate not supplied

Apoptosis of human primary and metastatic colon adenocarcinoma cell lines in vitro induced by 5-fluorouracil, verapamil, and hyperthermia.

Combined verapamil(V) and hyperthermia(HT) showed a significant decrease in HT29 and SW-620 cell counts by 61.5% and 77.6%, respectively, when compared to control. V in conjunction with 5-FU significantly reduced HT-29 count by 37% in comparison to 5-FU alone, and did not enhance the growth inhibitory effect of 5-FU on SW-620. HT did not enhance the growth inhibition seen with 5-FU treatment alone on HT-29, while this combination significantly decreased SW-620 cell count by 28.9% in comparison to administration of 5-FU alone. Joint administration of V and HT with 5-FU appeared to have a possible synergistic effect and reduced HT-29 count by 90% when compared to control. 5-FU alone or in different combinations with V and HT, as well as combination V+HT, results in apoptosis.

Adenocarcinoma↗
PubMedDate not supplied

Hyperthermia and verapamil inhibit the growth of human colon cancer xenografts in vivo through apoptosis.

BACKGROUND: The long-term goal of this work is to develop a new therapeutic regimen for the treatment of colon cancer in humans which will include hyperthermic intraperitoneal perfusion of verapamil as an alternative to administration of chemotherapy. METHODS AND RESULTS: Hyperthermia and verapamil caused a significant inhibition of the growth of human colon cancer (HT-29) xenografts. Both apoptosis detection assays, TUNEL and H and E staining, have shown that approximately 50% of human colon cancer cells underwent apoptosis after hyperthermia and verapamil administration. The TUNEL assay has demonstrated that DNA strand breaks appeared fairly rapidly and maximum breakage occurred at 2 hours after the treatment. Histopathological assay has showed maximum apoptotic morphological changes at 12 hours after treatment. CONCLUSION: Thus, the results of our in vivo experiments confirmed our previously obtained in vitro data concerning the significant ability of the combination of hyperthermia and verapamil to inhibit human colon cancer cell growth through programmed cell death.

Animals↗