Biomedical subjects
Publications and source records attributed to T J Flotte.
DNA ploidy of paraffin-embedded tissue from 11 patients with epithelioid sarcoma and 20 control specimens (granuloma annulare and sarcoid) was studied. DNA aneuploidy was found in 64% of the epithelioid sarcomas and in none of the control samples. Aneuploidy did not correlate with necrosis, vascular invasion, or mitotic rate. There was also no association of aneuploidy with adverse outcome.
Multiple short argon laser pulses can coagulate the retinal pigment epithelium selectively, while sparing the adjacent neural retina and choroid; in contrast, continuous-wave laser irradiation typically damages the neural retina and choroid. The healing response to selective photocoagulation of the retinal pigment epithelium was studied in rabbits during a period of 4 weeks. The lesions were never visible ophthalmoscopically. During the healing period, the epithelium was reformed by a single sheet of hypertrophic retinal pigment epithelial cells. In contrast to continuous-wave photocoagulation, only minimal inflammatory response was found. Retinal pigment epithelial cells showed clear signs of viability, eg, phagocytized outer segments. The local edema in the photoreceptor layer and subretinal space found in the early stage disappeared when the blood-retinal barrier was reestablished. The choriocapillaris remained unaffected. No subsequent damage to the photoreceptors was found. This type of photocoagulation may be useful for retinal pigment epithelium-related diseases, eg, diffuse diabetic macular edema.
Laser-induced fluorescence (LIF) of colonic tissue was examined both in vitro and in vivo to assess the ability of the technique to distinguish neoplastic from hyperplastic and normal tissue and to relate the LIF spectra to specific constituents of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, 49 adenomatous polyps, and 7 adenocarcinomas were recorded both in vivo and in vitro. With 337-nm excitation, the fluorescence spectra all had peaks at 390 and 460 nm, believed to arise from collagen and NADH, and a minimum at 425 nm, consistent with absorption attributable to hemoglobin. The spectra of colonic tissue recorded both in vivo and in vitro are different, primarily in the NADH fluorescence component, which decays exponentially with time after resection. When normal colonic tissue is compared to hyperplastic or adenomatous polyps, the predominant changes in the fluorescence spectra are a decrease in collagen fluorescence and a slight increase in hemoglobin reabsorption. A multivariate linear regression (MVLR) analysis was used to distinguish neoplastic tissue from non-neoplastic tissue with a sensitivity, specificity, predictive value positive, and predictive value negative toward neoplastic tissue of 80%, 92%, 82%, and 91%, respectively. When the MVLR technique was used to distinguish neoplastic polyps from non-neoplastic polyps, values of 86%, 77%, 86%, and 77% respectively, were obtained. The data suggest that the LIF measurements sense changes in polyp morphology, rather than changes in fluorophores specific to polyps, and it is this change in morphology that leads indirectly to discrimination of polyps.
The ablation thresholds and patterns of collateral damage in cornea produced by Er:YAG (2.94 microns) and Er:YSGG (2.79 microns) lasers were measured. Two different pulse durations, 200 microseconds (normal spiking mode) and 100 ns (Q-switched mode), were used at both wavelengths. In the normal spiking mode, damage zones of 16 +/- 2 microns and 39 +/- 7 microns and ablation thresholds of 250 +/- 20 mJ/cm2 and 420 +/- 35 mJ/cm2 were measured at 2.94 microns and 2.79 microns, respectively. In the Q-switched mode, damage zones of 4 +/- 2 microns and ablation thresholds of 150 +/- 10 mJ/cm2 were found irrespective of the laser used. The similarity between the results using the Er:YAG and Er:YSGG lasers in the Q-switched mode suggest that either laser can be used with equal effectiveness for corneal trephination.
Paraffin-embedded tissue from 38 patients with early- and advanced-stage juvenile granulosa cell tumor (JGCT) of the ovary was analyzed by flow cytometry to investigate whether the DNA content is related to the histologic features, stage, or clinical outcome. Thirty-three cases were suitable for analysis: twenty-seven Stage Ia, two Stage Ic, and four Stage III. Eighteen (55%) tumors were DNA diploid and fifteen (45%) tumors were DNA aneuploid with a mean S-phase fraction (SPF) of 13.6% and a range of DNA indices from 1.0 to 2.2. Neither the DNA ploidy nor the SPF was associated with the stage of the disease. An analysis of the relation between DNA content and histopathologic features revealed that aneuploidy was associated with high mitotic rates and to a lesser extent with high-grade nuclear atypia. DNA aneuploidy was not associated with aggressive behavior of Stage Ia JGCTs. However, among the four patients with Stage III tumors, the two with diploid, low-SPF tumors were alive and well, whereas the two with aneuploid, high-SPF tumors developed recurrences or died. These data suggest that further studies on the prognostic significance of flow cytometric analysis of DNA content in advanced-stage JGCTs are warranted.
Photodynamic therapy is an experimental treatment of superficial bladder tumors. Photofrin, a mixture of porphyrins, is the only photosensitizer in clinical use in the U.S.A. and its major side effect is prolonged cutaneous phototoxicity. In order to circumvent this problem of phototoxicity, new photosensitizers are being examined. Cutaneous phototoxicity may also be minimized by local administration of photosensitizer. Therefore, in this study, we investigated the photosensitizer chloro-aluminum sulfonated phthalocyanine (CASPc) in vivo in a rat bladder carcinoma model, and compared two different routes of CASPc administration. AY-27 rat bladder carcinoma cells were transplanted into rat bladders. Eight days after tumor transplantation the biodistribution of CASPc in bladder, skin, muscle and bladder tumor was determined by fluorescence measurements after dye extraction. Photosensitizer administered by intravenous injection and intravesical instillation, were compared. The concentration of CASPc in bladder and bladder tumor after intravenous injection and intravesical instillation was similar. The ratio of dye uptake between tumor and normal bladder after either administration was approximately two. Although no systemic absorption of the photosensitizer was observed after intravesical instillation, there was no reduction in tumor uptake or in the ratio between tumor to normal surrounding tissue. Therefore, no systemic side effects of skin phototoxicity are expected upon intravesical instillation. The microscopic biodistribution of CASPc after intravenous injection and intravesical instillation was also compared. After intravenous injection, the photosensitizer was distributed within the whole tumor with increased fluorescence around the microvasculature. In the normal bladder wall, weak fluorescence was seen in the area of the vasculature in the submucosa and the muscularis. After intravesical instillation, strong fluorescence was detected only at the tumor surface and in normal urothelium; no fluorescence was found in other areas of the tumor or in submucosa or muscularis. A comparison of the photodynamic treatment of model bladder tumors showed that tumor destruction after either method was similar but that there were less side effects to normal bladder wall after intravesical instillation of the CASPc. Intravesical administration of photosensitizers may, therefore, be a viable alternative to intravenous injection with potential for reduced systemic and normal tissue toxicity.
Ovarian small cell carcinoma of the hypercalcemic type is a rare cancer of young women of nuclear histogenesis. Although usually lethal, a subset of patients with stage I tumors have survived. Twenty-five cases of small cell carcinoma (17 stage I, 1 stage II, and 7 stage III) were evaluated by flow cytometric analysis performed on paraffin-embedded tissue. Forty classifiable histograms from 23 cases were DNA diploid; histograms from two cases could not be interpreted. The mean S-phase fraction was 10.5% (4.7% to 18.4%), and the mean G2/M fraction was 5% (1.5% to 19.5%) in 22 cases. Mean values of mitotic rate, S-phase fraction, G2/M fraction, and proliferation index (%S + %G2/M) were not associated with stage or outcome, nor did any proliferation variable correlate with interval to death. A comparative review of flow cytometric findings in other types of ovarian cancer that may be confused with small cell carcinoma indicates that flow cytometry is an objective diagnostic aid to distinguish small cell carcinoma of the hypercalcemic type from other forms of small cell carcinoma, malignant germ cell tumors, and sex-cord tumors, and that small cell carcinoma probably does not belong in either the surface epithelial or germ cell categories of ovarian cancer. Finally, the flow cytometric findings in this report exemplify the rare phenomenon of a diploid DNA content in a very lethal tumor and indicate that an accurate diagnosis of tumor type is essential before a prognosis on the basis of flow cytometric data can be made.
The purpose of this study was to determine whether quantification of DNA content would demonstrate conserved patterns in primary tumors and their metastases and to learn whether this technique would be useful in determining if a tumor was metastatic from a previous primary tumor or represented a new neoplasm. The study comprised of all cases nonmelanoma metastatic skin lesions in which the primary tumor was also resected at this hospital between the years 1984 and 1990 (22 cases). Both the primary and metastatic lesions were examined by the deparaffinized flow cytometric technique for DNA content. DNA-aneuploid tumors were considered to correlate if the DNA indices (ratio of aneuploid to diploid peak channels) were within 10%. Thirty-four tumors were DNA-aneuploid; eight tumors were DNA-diploid. We found agreement in 20 of 22 cases (agree--aneuploid: 16 cases; agree--diploid: four cases). In six of our cases the histograms of the primary and the metastatic lesions did not correlate when only one block was examined; however, when three blocks from each site were studied, we found concordance of DNA indices in four cases. There was disagreement in two of 22 cases (disagree--different DNA indices: two cases). In both of these cases, only one block of the primary tumor was available for examination, and the histograms were of marginal quality. This study demonstrates that the histogram pattern (aneuploid versus diploid) of DNA content is highly conserved between primary and metastatic tumors. There was 91% agreement between DNA indices of primary tumors and their metastases (20 of 22 cases) using a 10% correlation criterion.(ABSTRACT TRUNCATED AT 250 WORDS)
BACKGROUND: Photodynamic therapy (PDT) uses light activation of otherwise nontoxic dyes for the production of reactive oxygen species that cause cell injury and death. METHODS AND RESULTS: The inhibition of intimal hyperplasia (IH) by PDT was studied in the balloon injury model of the rat carotid artery. Chloroaluminum-sulfonated phthalocyanine (CASPc) was the drug chosen for PDT because it does not produce skin photosensitivity and has a high absorption peak of light at 675 nm, a wavelength with good tissue penetration. A pilot study indicated that CASPc administration with laser radiant exposure of 100 J/cm2 resulted in a homogeneous, circumferential effect on the whole artery. Male Sprague-Dawley rats received the balloon catheter injury to the left common carotid artery (day 0) and were equally divided into two groups. Nine rats received either CASPc (5 mg/kg i.v., n = 6) or saline (n = 3) at day 2, before IH was present, and nine rats received CASPc or saline in the same manner on day 7, when IH was already present. Twenty minutes after drug injection, the distal left common carotid artery was irradiated under saline with 675-nm laser light at 100 mW/cm2 for 10(3) seconds (100 J/cm2). At this low laser irradiance, there are no thermal effects, but photoactivation of CASPc occurs. The rats were killed at day 14 after balloon injury when IH reaches a maximum. The arteries were harvested after perfusion-fixation for light microscopy, histological and computerized morphometric evaluation, and transmission electron microscopy (TEM) analysis. The cross-sectional areas of the neointima were measured in the PDT-treated arteries and in the laser-only control arteries. There was a significant mean +/- SD decrease of IH in the PDT-irradiated segments of the arteries (0.06 +/- 0.05 mm2) versus the laser-only control ones (0.17 +/- 0.07 mm2) (t test, p less than 0.001), with no statistical difference between the day 2 and day 7 treated rats. Lack of IH was correlated in 90% of cases with histological absence of medial smooth muscle cells or inflammatory cells, but no other structural injury was identified. TEM analysis showed early evidence of PDT-mediated cytotoxic effects at 4 hours and the absence of collagen or elastic tissue structural alterations. CONCLUSIONS: These data demonstrated that PDT can effectively inhibit the IH response when it is used before or during induction of cellular proliferation in this acute model. Although the long-term implications of PDT in arteries need to be defined, this technique may offer a new method for understanding and treating IH.
OBJECTIVE: The purpose of this study was to investigate the feasibility of using a holmium:yttrium-aluminum-garnet laser to permanently occlude the cystic duct in order to isolate the gallbladder from the biliary-enteric circulation and prevent gallstone formation. MATERIALS AND METHODS: To determine the optimal laser parameters (power and pulsing rate) for cystic duct thermocoagulation, 20 freshly excised porcine gallbladders with intact cystic ducts underwent low-energy (0.075-0.085 J/pulse) or high-energy (0.20-0.25 J/pulse) thermocoagulation. Histopathologic examination was done to determine the extent of cystic duct injury. After in vitro experiments, percutaneous transcholecystic laser thermocoagulation of the cystic duct was performed on 23 anesthetized domestic pigs (four controls). Cholangiograms immediately after laser thermocoagulation were obtained to assess cystic duct occlusion. Animals were sacrificed for histopathologic correlation immediately after laser thermocoagulation (n = 4), 72 hr later (n = 4), and 6 weeks later (n = 15). RESULTS: In the in vitro studies, all 10 cystic ducts in the high-energy group were occluded, while only four in the low-energy group were occluded. At histology, all cases in both groups showed circumferential injury to the cystic duct wall without injury to the cystic artery or vein. In the in vitro experiments, the cystic duct was successfully cannulated in 21 (91%) of 23 animals. Cholangiography after thermocoagulation showed occlusion of the cystic duct in 16 (84%) of 19 cases. Immediately after laser thermocoagulation, the cystic duct mucosa was circumferentially destroyed, whereas after 72 hr necrosis of the cystic duct wall and periductal tissues had occurred. By 6 weeks, all pigs had complete cystic duct fibrosis without injury to the common bile duct. CONCLUSION: Holmium:yttrium-aluminum-garnet laser thermocoagulation of the cystic duct can be performed easily, results in immediate cystic duct occlusion, and leads to permanent fibrous ductal obliteration by 6 weeks.
OBJECTIVE: Chemical gallbladder sclerosis has been attempted as a way to defunctionalize the gallbladder in patients who have undergone nonsurgical removal of gallstones and who are unable to undergo surgical/laparoscopic cholecystectomy. The purpose of this investigation was threefold: to study an animal model for chemical sclerosis of the gallbladder with 95% ethanol and 3% sodium tetradecyl sulfate, to attempt chemical sclerosis immediately after percutaneous cystic duct obliteration by laser thermocoagulation, and to assess histopathologic changes in the gallbladder after sclerosis. MATERIALS AND METHODS: Percutaneous cholecystostomy and laser thermocoagulation of the cystic duct was performed in 13 pigs. Eight pigs underwent immediate gallbladder sclerosis with 95% ethanol and 3% sodium tetradecyl sulfate while two pigs received 95% ethanol only. The remaining three pigs served as controls. The cholecystostomy catheter was removed immediately after the procedure. All animals were sacrificed 6 weeks after laser thermocoagulation. Multiple sections through the gallbladder, which included the adjacent liver, the cystic duct, and the common bile duct, were obtained for histologic examination. RESULTS: At autopsy, the gallbladder in all 10 animals who underwent gallbladder sclerosis was reduced in size compared with controls. In all treated animals, the gallbladder mucosa was denuded; however, in nine of 10 cases reepithelialization had occurred. Complete sclerosis without reepithelialization was achieved in one pig who received both ethanol and sodium tetradecyl sulfate. In the two animals who received ethanol only, the depth of wall necrosis around the gallbladder lumen was less than in those pigs who received both ethanol and sodium tetradecyl sulfate. No pigs showed signs of hepatic necrosis or injury to the common bile duct. CONCLUSION: Cystic duct laser thermocoagulation allows immediate gallbladder sclerotherapy without injury to the common bile duct. Sclerosis with ethanol and sodium tetradecyl sulfate results in denudation of the gallbladder mucosa. However, a single therapeutic session with immediate removal of the cholecystostomy catheter was inadequate for gallbladder ablation in this model because of reepithelialization.
The purpose of this study was to establish a morphometric technique that would approximate the subjective histological criteria of asymmetry in the diagnosis of malignant melanoma. The dermal and epidermal outlines of 52 consecutive malignant melanomas and 56 consecutive melanocytic nevi were digitized and analyzed for morphometric parameters of size, coordinates, and shape. The two parameters that showed the most significant discriminatory functions were the differences in the center of masses of the epidermal and dermal components in the horizontal dimension and the length of the longest segment in the lesion.
Ultraviolet laser-induced fluorescence was examined in vivo to determine whether the technique can reliably distinguish between hyperplastic and adenomatous polyps of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, and 49 adenomatous polyps were recorded in vivo. Polyp type was independently determined by two senior pathologists who were unaware of the fluorescence measurement. A multivariate linear regression analysis was used to differentiate spectra from hyperplastic and adenomatous polyps and resulted in a sensitivity, specificity, predictive value positive, and predictive value negative for identifying adenomatous polyps of 86%, 80%, 86%, and 80%, respectively. These values were not significantly different from the accuracy of routine clinical pathology. Thus, ultraviolet laser-induced fluorescence appears to show promise as a means for distinguishing tissue types. However, further experience is needed before its routine clinical use can be recommended. Significant changes in the fluorescence spectra occurred postmortem, suggesting that future studies of laser-induced fluorescence of colonic tissue must use data acquired in vivo.
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Argon-fluoride (ArF) excimer laser-induced acoustic injury was confirmed by ablating the stratum corneum (s.c.) inertially confined by water in vivo. Hairless rats were irradiated through a quartz chamber with flowing distilled water or air and a 2.5 mm aperture. The laser was adjusted to deliver 150 mJ/cm2 at the skin surface for both conditions. Partial and complete ablation of the s.c. was achieved with 12 and 24 pulses, respectively. Immediate damage was assessed by the transmission electron microscopy. Partial ablation of the s.c. through air produced no damage, whereas partial ablation through water damaged skin to a mean depth of 114.5 +/- 8.8 microns (+/- SD). Full thickness ablation of the s.c. through air and water produced damage zones measuring 192.2 +/- 16.2 and 293.0 +/- 71.6 microns, respectively (P less than 0.05). The increased depth of damage in the presence of inertial confinement provided by the layer of water strongly supports a photoacoustic mechanism of damage. The damage induced by partial ablation of the s.c. provides evidence that photochemical injury is not a significant factor in the damage at a depth because the retained s.c. acts as a partial barrier to diffusion of photochemical products. Combined with our previous studies, these experiments demonstrate that pressure transients are responsible for the deep damage seen with 193 nm ablation and that photoacoustic effects must be considered when using short-pulse, high-peak power lasers.
The wavelength dependence of the ablation threshold of a variety of tissues has been studied by using a tunable pulsed Co:MgF2 laser to determine how closely it tracks the optical absorption length of water. The Co:MgF2 laser was tuned between 1.81 and 2.14 microns, a wavelength region in which the absorption length varies by a decade. For soft tissues the ablation threshold tracks the optical absorption length; for bone there is little wavelength dependence, consistent with the low water content of bone. Thermal damage vs. wavelength was also studied for cornea and bone. Thermal damage to cornea has a weak wavelength dependence, while that to bone shows little wavelength dependence. Framing-camera pictures of the ablation of both cornea and liver show explosive removal of material, but differ as to the nature of the explosion.
Short-pulse laser exposures can be used to alter pigmented structures in tissue by selective photothermolysis. Potential mechanisms of human tattoo pigment lightening with Q-switched ruby laser were explored by light and electron microscopy. Significant variation existed between and within tattoos. Electron microscopy of untreated tattoos revealed membrane-bound pigment granules, predominantly within fibroblasts and macrophages, and occasionally in mast cells. These granules contained pigment particles ranging from 2-in diameter. Immediately after exposure, dose-related injury was observed in cells containing pigment. Some pigment particles were smaller and lamellated. At fluences greater than or equal to 3 J/cm2, dermal vacuoles and homogenization of collagen bundles immediately adjacent to extracellular pigment were occasionally observed. A brisk neutrophilic infiltrate was apparent by 24 h. Eleven days later, the pigment was again intracellular. Half of the biopsies at 150 d revealed a mild persistent lymphocytic infiltrate. There was no fibrosis except for one case of clinical scarring. These findings confirm that short-pulse radiation can be used to selectively disrupt cells containing tattoo pigments. The physial alteration of pigment granules, redistribution, and elimination appear to account for clinical lightening of the tattoos.
The distinction of mycosis fungoides from benign inflammatory lesions is sometimes difficult by conventional histological techniques. Aneuploidy, a feature often associated with malignant tumors, can be assessed even in tissue routinely processed in paraffin using the flow cytometric technique of Hedley and associates. In many tumor systems, there are significant diploid clones. We have evaluated the flow cytometric DNA ploidy of paraffin-embedded tissue in the diagnosis and prognosis of mycosis fungoides (MF). We studied 22 cases of MF and 10 control cases of inflammatory skin lesions with epidermal involvement. Aneuploidy was found in 27% of the MF cases, but in none of the controls (ED). Aneuploid features were seen in 23% of tissues from early stage disease. Aneuploidy did not correlate with atypia, epidermotropism, or number of mitoses. There was a trend towards showing adverse outcome in those patients with aneuploid lesions. The detection of aneuploidy might be helpful for early diagnosis of MF.