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S J Stern

Publications and source records attributed to S J Stern.

31 records · Page 2Linked to original sources
PubMed1991

An implantable tumor-window chamber model for the study of photodynamic therapy.

In order to study both the anti-tumor effects and early vascular events in photodynamic therapy, a useful animal model has been developed. A window chamber is surgically placed on the dorsum of the Fischer-344 rat, and 500-microns fragments of the rat mammary adenocarcinoma 13672 are placed under direct vision into the subcutaneous tissue. Implantation of the chamber has been successfully completed in more than 50 rats. The operative procedure is straightforward and is accomplished in less than 1 hour. Using tumor fragments, tumor viability has been 60%. We have demonstrated obvious and reproducible neovascularization occurring as soon as 1 day after implantation. The application of this system to an experimental protocol comparing the photosensitizers dihematoporphyrin ether (DHE) and chloraluminum sulfonated phthalocyanine (CASP) has yielded important information on early vascular events resulting from photodynamic therapy.

Adenocarcinoma↗
PubMed1991

Chloroaluminum sulfonated phthalocyanine versus dihematoporphyrin ether: early vascular events in the rat window chamber.

The development of a simple and well-tolerated rat window chamber has allowed direct comparison of the vascular effects of two photosensitizers, chloroaluminum sulfonated phthalocyanine (CASP) and dihematoporphyrin ether (DHE). CASP and DHE were given 4 days after the implantation of the window chamber. Photodynamic therapy (PDT) with CASP was performed 24 hours after intravenous injection (10 mg/kg) with light at 675 nm (power density 200 mW/cm2, incident energy 100 J). DHE was given in a similar fashion (5 mg/kg intraperitoneally; light at 630 nm with matching power density and energy settings 24 hours after injection). Using videomicroscopic and integrating sphere measurements, marked differences were noted in the vascular effects of these photosensitizers. DHE caused immediate hemorrhage and disruption of the postcapillary venules, while CASP induced vascular spasm starting 4 hours after the completion of PDT. Forty-eight hours after PDT, both systems demonstrated a loss of chamber-induced neovascularization.

Animals↗
PubMed1990

Photodynamic therapy with chloroaluminum-sulfonated phthalocyanine.

To study the vascular effects of a new photosensitizing agent independent of the influence of tumor growth, a cutaneous wound model was used. Six-week-old Harlan-Sprague-Dawley "Fuzzy" rats were surgically wounded in a standard fashion. The animals were then divided into three groups: the first group received chloroaluminum-sulfonated phthalocyanine only, the second group was treated with light only, and a third group was treated with both chloroaluminum-sulfonated phthalocyanine and light. Photodynamic therapy with chloroaluminum-sulfonated phthalocyanine had a direct effect on the neovasculature of a healing wound. The vasodilatation that was seen in the wound neovasculature that occurred 12 hours after the completion of chloroaluminum-sulfonated phthalocyanine-photodynamic therapy may have indicated a therapeutic "window" at which other therapies can be employed to improve clinical efficacy.

Animals↗
PubMed1990

Photodynamic therapy with chloroaluminum sulfonated phthalocyanine in the rat window chamber.

The efficacy of photodynamic therapy tumor destruction is dependent upon both the interruption of the tumor vasculature and the resultant production of unstable oxygen species causing cellular oxidation and death. Chloroaluminum sulfonated phthalocyanine (CASP) is a recently developed photosensitizer. In order to study the direct vascular effects of CASP on a non-tumor system, a rat window chamber was utilized. Twelve rats were implanted with the window chamber, and were divided into two groups of six. Three rats served as controls for each group (receiving light alone, CASP alone, or no treatment). The remaining 6 rats received 10 mg/kg CASP intravenously 4 days after chamber placement. Photoactivation with light was performed 24 hours after injection (power density 200 mW/cm2, irradiance 100 J/cm2, lambda = 675 nm). Utilizing integrating sphere measurements and image analysis, marked vascular changes in the form of initial vasospasm followed by vaso-constriction and loss of chamber neovascularization were noted in the CASP-PDT group. The control groups exhibited no significant changes. Manipulation of the chamber vasculature at strategic time-points may translate into improved response rates for photodynamic therapy in a tumor model.

Animals↗
PubMedDate not supplied

Histologic effect of doxycycline sclerotherapy on rat femoral nerve.

BACKGROUND: This study stems from an encounter with a phrenic nerve paralysis in a patient following doxycycline sclerotherapy for treatment of chylous fistula. The purpose of this study is to identify possible histologic evidence of doxycycline-induced nerve injury. METHODS: The femoral nerves of CD rats were used as the in vivo animal model. The nerves were exposed to varying concentrations doxycycline and normal saline was the control. The nerves were studied at several time intervals using two different staining techniques. RESULTS: The results suggest that topical doxycycline induces tissue reactions which are different from normal saline. These reactions include stimulation of a local giant cell inflammatory reaction and disruption of the myelin sheath. CONCLUSIONS: Despite the fact that this study does not give physiologic evidence of neurotoxicity, the histologic results suggest that topical doxycycline may cause nerve damage directly or indirectly. We conclude that doxycycline should not be used for sclerotherapy where unprotected nerves are exposed to the agent until further physiologic tests are performed to prove its safety.

Administration, Topical↗
PubMedDate not supplied

Mucosal melanoma of the head and neck.

Forty-two patients with mucosal melanoma of the head and neck were treated at the M. D. Anderson Cancer Center from 1944-1989. Their records were evaluated regarding: location of the primary, stage of the disease at presentation, type of treatment, location of recurrences, and overall survival. These patients received the majority of their therapy at M. D. Anderson Cancer Center. The treatment consisted of surgery, radiotherapy, chemotherapy, immunotherapy, or a combination of these. The 5-year survival rate was 40%. Twenty-four of 27 patients who died with metastatic melanoma had local or regional disease concomitantly. Forty percent of patients were free of disease at 5 years; however, only 26% had long-term survival. Although the majority of patients eventually succumbed to their disease, local and regional control was obtained initially in 92% of the group. These data indicate that prolonged survival is possible with mucosal melanoma of the head and neck; however, recurrence or metastasis remain possible many years after the initial diagnosis.

Adult↗
PubMedDate not supplied

Anatomy of the lateral pharyngotomy approach.

The pace of progress in head and neck surgery is rapid and can be bewildering to practitioners and students alike. As education is one of the major missions of Head & Neck, this new series is devoted to a comprehensive discussion of basic anatomical concepts manifested in the diagnosis, treatment, and care of patients with diseases of the head and neck. Although the anatomy of the head and neck region as related to surgical procedures will certainly be discussed, this will by no means be the only subject addressed. Other topics include the anatomic basis for specific pain syndromes encountered in patients with cancer of the head and neck, structural and lymphatic anatomy demonstrating patterns of disease spread, and constraints to standard surgical procedures because of anatomic "barriers." As medical illustration is an extremely important aspect of anatomy education, a concerted effort will be made to present material with illustrations that are understandable, clear, and concise. It is hoped that these subjects will not only educate but will also engender other topics of interest to readers. I welcome your suggestions for appropriate topics, as well as original contributions in keeping with the series guidelines.

Humans↗
PubMedDate not supplied

Low genetic variation among killer whales (Orcinus orca) in the eastern north Pacific and genetic differentiation between foraging specialists.

Killer whales from the coastal waters off California through Alaska were compared for genetic variation at three nuclear DNA markers and sequenced for a total of 520 bp from the mitochondrial control region. Two putative sympatric populations that range throughout this region were compared. They can be distinguished by social and foraging behavior and are known as "residents" and "transients". We found low levels of variation within populations compared to other cetacean species. Comparisons between fish (resident) versus marine mammal (transient) foraging specialists indicated highly significant genetic differentiation at both nuclear and mitochondrial loci. This differentiation is at a level consistent with intraspecific variation. A comparison between two parapatric resident populations showed a small but fixed mtDNA haplotype difference. Together these data suggest low levels of genetic dispersal between foraging specialists and a pattern of genetic differentiation consistent with matrifocal population structure and small effective population size.

Alleles↗