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Biomedical subjects

B F Overholt

Publications and source records attributed to B F Overholt.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

Laser and photodynamic therapy of esophageal cancer.

With proper selection of patients with non-operative esophageal cancer, palliative therapy with Nd:YAG laser enhances the quality of life by improving the patient's ability to swallow soft or solid food. Also, the use of non-thermal laser light to initiate the process of photodynamic therapy (PDT) is an additional laser technique that appears effective, not just in palliative treatment, but also in the cure of early esophageal cancer. For PDT, considerable work will be necessary to provide standard techniques in tumor staging, light and drug delivery and in light dosimetry. Ultimately, palliative and curative therapy of esophageal cancer will most likely incorporate multiple modalities, including surgery, radiation, chemotherapy, stents, laser and other thermal modalities, photodynamic therapy, and combinations of these methods.

Antineoplastic Agents↗
PubMedDate not supplied

Photodynamic therapy in Barrett's esophagus: reduction of specialized mucosa, ablation of dysplasia, and treatment of superficial esophageal cancer.

Twelve patients with Barrett's esophagus and dysplasia were treated with photodynamic therapy. Five patients also had early, superficial esophageal cancers and five had esophageal polyps. Light was delivered via a standard diffuser or a centering esophageal balloon. Patients were maintained on omeprazole and followed for 6-54 months. In patients with Barrett's esophagus, photodynamic therapy ablated dysplastic mucosa and malignant mucosa in patients with superficial cancer. Healing and partial replacement of Barrett's mucosa with normal squamous epithelium occurred in all patients and complete replacement with squamous epithelium was found in three patients. Side effects included photosensitivity and mild-moderate chest pain and dysphagia for 5-7 days. In four patients with extensive circumferential mucosal ablation in the mid or proximal esophagus, healing was associated with esophageal strictures which were treated successfully by esophageal dilation. Strictures were not found in the distal esophagus. Photodynamic therapy combined with long-term acid inhibition provides effective endoscopic therapy of Barrett's mucosal dysplasia and superficial (Tis-T1) esophageal cancer. The windowed centering balloon improves delivery of photodynamic therapy to diffusely abnormal esophageal mucosa.

Adenocarcinoma↗
PubMedDate not supplied

A centering balloon for photodynamic therapy of esophageal cancer tested in a canine model.

Delivery of uniform circumferential light is desirable during photodynamic therapy of early or advanced esophageal cancer in human beings. Studies were performed in the canine esophagus to investigate whether use of a centering balloon would improve circumferential illumination of esophageal mucosa for photodynamic therapy of esophageal cancer. When the centering balloon was used, photodynamic therapy produced uniform and circumferential injury. With the cylindrical diffuser used in human studies, non-uniform and focal esophageal injury occurred. Placement of isotropic probes on the balloon wall allowed measurement and verification of relatively uniform light doses delivered to esophageal mucosa during balloon photodynamic therapy. The centering balloon has a potential role in improving light dosimetry during esophageal photodynamic therapy.

Animals↗
PubMedDate not supplied

Acid suppression and reepithelialization after ablation of Barrett's esophagus.

The role of acid reflux in the development of esophageal columnar epithelium was first described in the early 1970s in the canine esophageal reflux model. In the presence of acid reflux, columnar epithelium developed at the site of induced esophageal mucosal injury. When reflux was suppressed, most epithelium reverted back to squamous mucosa. Similar findings in human patients with Barrett's esophagus (BE) who were treated with laser ablation were first described in 1993. While acid suppression with antireflux surgery or proton pump inhibitors (PPIs) has proven insufficient to completely reverse BE, ablation of the lesion followed by acid suppression may be a promising option. Although at least one report disputes the importance of complete acid suppression following mucosal ablation of BE, most investigators use full-dose PPI therapy following ablation, in the belief that full acid suppression provides an environment that allows the esophageal progenitor cell to develop squamous mucosa. This article provides a review of the literature to date regarding ablative therapies and acid suppression for patients with BE.

Animals↗