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Biomedical subjects

N E Marcon

Publications and source records attributed to N E Marcon.

At least 19 recordsLinked to original sources
PubMed2005

Autofluorescence characterisation of isolated whole crypts and primary cultured human epithelial cells from normal, hyperplastic, and adenomatous colonic mucosa.

BACKGROUND/AIMS: In vivo autofluorescence endoscopic imaging and spectroscopy have been used to detect and differentiate benign (hyperplastic) and preneoplastic (adenomatous) colonic lesions. This fluorescence is composed of contributions from the epithelium, lamina propria, and submucosa. Because epithelial autofluorescence in normal and diseased tissues is poorly understood, this was the focus of the present study. METHODS: Whole colonic crypts were isolated, and short term primary cultures of epithelial cells were established from biopsies of normal, hyperplastic, and adenomatous colon. Autofluorescence (488 nm excitation) was examined by confocal fluorescence microscopy. Fluorescently labelled organelle probes and transmission electron microscopy were used to identify subcellular sources of fluorescence. RESULTS: Mitochondria and lysosomes were identified as the main intracellular fluorescent components in all cell types. Normal and hyperplastic epithelial cells were weakly autofluorescent and had similar numbers of mitochondria and lysosomes, whereas adenomatous (dysplastic) epithelial cells showed much higher autofluorescence, and numerous highly autofluorescent lysosomal (lipofuscin) granules. CONCLUSIONS: Short term primary cell cultures from endoscopic biopsies provide a novel model to understand differences in colonic tissue autofluorescence at the glandular (crypt) and cellular levels. The differences between normal, hyperplastic, and adenomatous epithelial cells are attributed in part to differences in the intrinsic numbers of mitochondria and lysosomes. This suggests that the detection of colonic epithelial fluorescence alone, if possible, may be sufficient to differentiate benign (hyperplastic) from preneoplastic and neoplastic (adenomatous) colonic intramucosal lesions during in vivo fluorescence endoscopy. Furthermore, highly orange/red autofluorescent intracellular granules found only in dysplastic epithelial cells may serve as a potential biomarker.

Adenomatous Polyps↗
PubMed2001

Endoscopy in the elderly patient.

In the elderly who require endoscopy for diagnosis and /or intervention, the endoscopist should be aware of the special risks related to the presence of concomitant systemic diseases. This is especially pertinent in the use of sedatives and analgesics due to the altered physiological functions related to ageing. This can be further complicated by the fact that elderly patients are often prescribed multiple drugs, which makes for the possibility of serious drug interactions. Endoscopy is a minimally invasive technique that is safer than conventional surgery in many conditions. The endoscopist must take into consideration the important factors related to quality of life, as well as the wishes of the patients and their families. The endoscopist must be sympathetic to their wishes and realize when investigation and treatment are not appropriate.

Aged↗
PubMed2000

A randomized, double-blind study of the use of droperidol for conscious sedation during therapeutic endoscopy in difficult to sedate patients.

BACKGROUND: Droperidol has been used in combination with narcotics and benzodiazepines to achieve conscious sedation. We performed a randomized, double-blind, study of droperidol in patients at risk for difficult sedation scheduled for therapeutic endoscopy. METHODS: Patients with regular ethanol, narcotic, or benzodiazepine usage, suspected sphincter of Oddi dysfunction, or a history of difficult sedation were eligible for the study. Patients were randomized to receive either droperidol or placebo along with midazolam and meperidine as preprocedure sedation. Time to achieve sedation, interruptions due to undersedation, medication dosages, recovery time, and subjective assessments of sedation were recorded. RESULTS: One hundred one patients were randomized. The droperidol group had significantly fewer procedure interruptions and observer ratings of difficulty with sedation and required significantly less midazolam (23%) and meperidine (16%) than the placebo group. There were no significant differences in time to achieve sedation, incomplete procedures, procedure length, recovery room time, or complications. There were significantly higher observer ratings of the quality of sedation for patients who received droperidol. CONCLUSIONS: Droperidol is a useful adjunct to conscious sedation in patients who are difficult to sedate. Its use results in significantly fewer interruptions due to poor sedation and improved sedation ratings compared with sedation using midazolam and meperidine alone.

Adjuvants, Anesthesia↗
PubMed2000

In vivo near-infrared Raman spectroscopy: demonstration of feasibility during clinical gastrointestinal endoscopy.

Raman spectroscopy (RS) has potential for disease classification within the gastrointestinal tract (GI). A near-infrared (NIR) fiber-optic RS system has been developed previously. This study reports the first in vivo Raman spectra of human gastrointestinal tissues measured during routine clinical endoscopy. This was achieved by using this system with a fiber-optic probe that was passed through the endoscope instrument channel and placed in contact with the tissue surface. Spectra could be obtained with good signal-to-noise ratio in 5 s. The effects on the spectra of varying the pressure of the probe tip on the tissue and of the probe-tissue angle were determined and shown to be insignificant. The limited set of spectra from normal and diseased tissues revealed only subtle differences. Therefore, powerful spectral-sorting algorithms, successfully implemented in prior ex vivo studies, are required to realize the full diagnostic potential of RS for tissue classification in the GI.

Colon↗
PubMed2000

Light-induced fluorescence endoscopy of the gastrointestinal tract.

The early detection of dysplasia and superficial malignant lesions of the gastrointestinal tract is of significant clinical importance. Recent advances in fluorescence-based endoscopic imaging and spectroscopy of the gastrointestinal tract may offer alternative means of detecting and identifying premalignant and malignant lesions that were otherwise occult or nonspecific on conventional white-light endoscopy. The purpose of this article is to present a general overview of the current developments and possible clinical roles of light-induced fluorescence endoscopy as an adjunct to routine diagnostic endoscopy to enhance screening and surveillance for premalignant and malignant gastrointestinal lesions.

Endoscopy, Gastrointestinal↗
PubMed1999

Is light-induced fluorescence better than the endoscopist's eye?

While recognizing advanced tumours with endoscopy does not generally pose a challenge, cure rates are relatively low, depending on the size and stage of the tumour. Screening tests for cancer are advantageous for diagnosing cancers before the date after which a cure is no longer an option. Many gastrointestinal cancers are diagnosed after the date on which a cure is possible. The present article discusses some of the limitations of conventional white light endoscopy in screening and presents some of the fluorescent-based diagnostics that are being investigated as complements to white light endoscopy. Autofluorescence and fluorescence due to exogenous photosensitizers or precursors are two sources of fluorescence that are being studied. Preliminary results of current investigations are presented, and future research directions are described.

Endoscopy, Gastrointestinal↗
PubMed1999

Expandable metal stents for benign esophageal obstruction.

Extensive experience with expandable metal stents for benign esophageal obstruction is limited. A review of the literature demonstrates a high incidence of complications varying from stent migration to stent-induced trauma leading to fistulization. The most common complication (41%) is that of stent-induced stenosis caused by granulation tissue and fibrosis. Currently, the authors do not recommend the routine use of expandable metal stents for benign obstruction. Each case must be assessed on its own merits and risks. The solution in the future may well have to be new stent configuration and esophagus-friendly materials.

Biocompatible Materials↗
PubMed1997

Photodynamic therapy for the treatment of tumor ingrowth in expandable esophageal stents.

BACKGROUND AND STUDY AIMS: Tumor ingrowth through self-expanding metal stents presents a difficult problem for management. The techniques for treating tumor ingrowth have not yet been well described, and the optimal endoscopic approach is not clear. We have recently used photodynamic therapy (PDT) to treat tumor ingrowth through uncovered nitinol mesh stents. PATIENTS AND METHODS: Four patients (mean age 73) with obstructive adenocarcinomas of the distal esophagus had received self-expanding stents for palliation of their dysphagia. After stent placement, tumor ingrowth had caused progressive dysphagia in all of the patients; the dysphagia was graded on a scale from 0 (normal) to 4 (inability to swallow liquids). All of the patients received PDT treatment. RESULTS: After PDT, excellent palliation of the dysphagia was seen in all of the patients, with a mean improvement in the dysphagia score of 2.25 and a mean dysphagia-free interval of 92 days. There were no major complications. CONCLUSION: The use of PDT to treat tumor ingrowth through self-expanding metal esophageal stents is effective and safe.

Adenocarcinoma↗
PubMed1997

Idiopathic colonic inflammation in AIDS: an open trial of prednisone.

OBJECTIVES: Idiopathic colonic inflammation and ulceration have been described in HIV infection, but only as isolated case reports. We have been treating this condition with a uniform corticosteroid protocol and now report our results. METHODS: We describe the cases of eight patients with HIV infection who had diarrhea for more than 4 wk and inflammation and/or ulceration in the colon at endoscopy, confirmed by biopsy, without any invasive pathogens despite extensive evaluation. Each patient was treated with prednisone, starting at 40 mg/day, then tapered according to a standardized protocol. RESULTS: The diarrhea completely resolved in three patients and partially improved in five. One patient had some improvement but was unable to tolerate the prednisone because of a severe exacerbation of anal warts. He responded to subtotal colectomy. After a minimum follow-up of 8 months (mean, 17 months), only one patient (complete response to prednisone) was found to have an enteric pathogen. In this patient, cytomegalovirus colitis was diagnosed 15 months after prednisone was started. CONCLUSION: Idiopathic colonic inflammation or ulceration in HIV infection (1) may respond to corticosteroid therapy without life-threatening side effects and (2) is only rarely followed by the detection of a recognized pathogen. These observations suggest that enteric pathogens are not missed by standard techniques.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Photodynamic therapy with porfimer sodium versus thermal ablation therapy with Nd:YAG laser for palliation of esophageal cancer: a multicenter randomized trial.

BACKGROUND: Photodynamic therapy (PDT) is a different type of laser treatment from Nd:YAG thermal ablation for palliation of dysphagia from esophageal cancer. METHODS: In this prospective, multicenter study, patients with advanced esophageal cancer were randomized to receive PDT with porfimer sodium and argon-pumped dye laser or Nd:YAG laser therapy. RESULTS: Two hundred thirty-six patients were randomized and 218 treated (PDT 110, Nd:YAG 108) at 24 centers. Improvement in dysphagia was equivalent between the two treatment groups. Objective tumor response was also equivalent at week 1, but at month 1 was 32% after PDT and 20% after Nd:YAG (p < 0.05). Nine complete tumor responses occurred after PDT and two after Nd:YAG. Trends for improved responses for PDT were seen in tumors located in the upper and lower third of the esophagus, in long tumors, and in patients who had prior therapy. More mild to moderate complications followed PDT, including sunburn in 19% of patients. Perforations from laser treatments or associated dilations occurred after PDT in 1%, Nd:YAG 7% (p < 0.05). Termination of laser sessions due to adverse events occurred in 3% with PDT and in 19% with Nd:YAG (p < 0.05). CONCLUSIONS: Photodynamic therapy with porfimer sodium has overall equal efficacy to Nd:YAG laser thermal ablation for palliation of dysphagia in esophageal cancer, and equal or better objective tumor response rate. Temporary photosensitivity is a limitation, but PDT is carried out with greater ease and is associated with fewer acute perforations than Nd:YAG laser therapy.

Adenocarcinoma↗
PubMed1994

Mucinous ductal ectasia: cholangiopancreatographic and endoscopic findings.

Mucinous ductal ectasia (MDE) is an uncommon disease characterized by a patulous duodenal papilla extruding mucus, and a pancreatogram showing dilation with amorphous filling defects, communication of the mass with the pancreatic duct, the mass usually being located in the head of the pancreas. We have recently treated three men and three women, mean age 66 years, with MDE. All had abdominal pain, while 33% had the clinical picture of pancreatic insufficiency. Three patients had recurrent pancreatitis, and three had biliary obstruction. Endoscopic retrograde cholangiopancreatography and imaging studies showed a patulous papilla draining mucus in six, pancreatic duct dilation in six, filling defects in six, and communication between the cystic mass and the pancreatic duct in five. A distinct finding not previously reported was a separate pancreatic and biliary orifice in two. Three patients had cancer, two cases being metastatic and one being found at surgery (not suspected preoperatively). Therapy included endoscopic biliary drainage in two, surgery in three, while one refused surgery. Of the operated patients, two underwent resection, one of whom had benign disease and the other cancer; both patients are doing well 14 and 32 months after surgery, respectively. One patient underwent pancreatojejunostomy without symptomatic relief, and developed cholangitis 18 months after surgery that was successfully treated with endoscopic drainage. The other two patients treated with biliary drainage died one and 13 months later, respectively. We conclude that MDE has characteristic pancreatographic and endoscopic findings, and that it is commonly associated with malignant degeneration. Surgical resection is the treatment of choice, since MDE is premalignant, and surgery may be curative when the malignancy is resectable.

Adenocarcinoma, Mucinous↗
PubMed1994

Appendiceal mucocele: endoscopic appearance.

Appendiceal mucocele is a rare disorder of the vermiform appendix, occurring predominantly in the sixth or seventh decades, and has a distinct female predominance. Very few cases have been reported in the endoscopic literature. We report two patients with appendiceal mucocele, describe and show the colonoscopic appearance of these tumors, and review the literature.

Adult↗
PubMed1994

Photodynamic therapy and cancer of the esophagus.

Esophageal carcinoma usually is diagnosed at an advanced, incurable stage. In patients with good operative risk, surgery is still considered the ideal treatment. Patients with coexisting major medical conditions in whom resective surgery is precluded may benefit from several therapeutic options, including photodynamic therapy (PDT) with porfimer sodium (Photofrin; manufactured by Lederle Parenterals, Carolina, Puerto Rico, under license from Quadra Logic Technologies, Inc, Vancouver, British Columbia, Canada), dilation, thermal destruction, Nd:YAG laser ablation, injection therapy, and placement of prosthetic tubes. Photodynamic therapy with porfimer sodium is thought to have a direct toxic effect on malignant cells via the production of singlet oxygen, which damages the microvasculature of the tumor and renders it ischemic. The 630 nm wavelength used for clinical PDT exhibits the greatest relative degree of light penetration into tissue, with corresponding activation of retained photosensitizer. The efficacy of PDT with porfimer sodium is closely related to stage of disease. It should be emphasized that PDT has been shown to be potentially curative in patients with early, noninvasive tumors of both squamous and glandular (adenocarcinoma) histologies. Eighty-three patients with esophageal carcinoma were treated using PDT. At presentation, 60% of patients had recurrence following previous radiotherapy or chemotherapy. Patients with less advanced disease had a better response to PDT with regard to relief of dysphagia and prolongation of survival. Photodynamic therapy was found to be more useful than Nd:YAG laser therapy for high, upper third lesions, especially circumferential ones. For tumors larger than 8 cm, PDT was twice as effective as Nd:YAG laser therapy in establishing prolonged lumen patency, especially for adenocarcinomas. Photodynamic therapy appears to have the added advantages of fewer treatments and less pain. The role of PDT in gastrointestinal malignancies continues to evolve.

Adenocarcinoma↗