Characteristics of the immunosuppression induced by cutaneous photodynamic therapy: persistence, antigen specificity and cell type involved.

Relatively little is known about the immunosuppression induced in mice which have received cutaneous photodynamic therapy (PDT). Consequently, experiments were undertaken using mice which received dorsal PDT using Photofrin as the photosensitizer in an attempt to characterize the overall nature of the immunosuppression. Photoirradiation of mice at various times after injection indicated there was no correlation between photosensitivity and immunosuppression. The suppression was found to be adoptively transferable and antigen specific suggesting the generation of suppressor cells. Selective cell depletions prior to adoptive transfer indicated a CD4+ T cell to be responsible for the immunosuppression. Interestingly, using allogeneic spleen cells, no effect on the delayed type hypersensitivity (DTH) response was found. The results indicate that the suppression induced by cutaneous PDT, with the exception of the lack of DTH suppression, is similar to that induced by UVB irradiation but unlike that reported using laser PDT of the peritoneal cavity. This suggests that not only the type of photoirradiation but also the site of photoirradiation might determine the character of the induced immunosuppression.

IL-10 does not play a role in cutaneous Photofrin photodynamic therapy-induced suppression of the contact hypersensitivity response.

Photodynamic therapy (PDT) treatment of both malignant and benign skin diseases has proven to be effective, and its use is increasing worldwide. However, preclinical studies using murine models have shown that PDT of the skin inhibits cell-mediated immune reactions, as measured by the suppression of the contact hypersensitivity (CHS) reaction. We have previously demonstrated that PDT enhances IL-10 expression in treated skin, and that the kinetics of induction of IL-10 is similar to the kinetics of suppression of systemic CHS reactions by cutaneous PDT. In the following report we have expanded upon these studies to demonstrate that cutaneous PDT, using Photofrin, induces elevated levels of systemic IL-10 that persist for at least 28 days following treatment. The increase in systemic IL-10 correlates to a prolonged suppression of CHS of at least 28 days following cutaneous PDT. IL-10 has been implicated as the causative agent in the suppression of cell-mediated immune reactions by UVB and transdermal PDT. However, in the studies reported here we demonstrate that the suppression of CHS by cutaneous PDT occurs via an IL-10 independent mechanism, as administration of anti-IL-10 antibodies had no effect on the ability of PDT to induce CHS suppression. These results were further confirmed using IL-10 knockout (KO) mice. Cutaneous PDT of IL-10 KO mice resulted in CHS suppression that was not significantly different from suppression induced in wild-type mice. Thus, it appears as though IL-10 does not play a role in CHS suppression by cutaneous PDT. Suppression of cell-mediated immune reactions by UVB and transdermal PDT is reversible by IL-12, which is critical for the development of these reactions. We show that administration of exogenous IL-12 is also able to reverse CHS suppression induced by cutaneous PDT, suggesting that whereas suppression of cell-mediated immune reactions by UVB, transdermal PDT and cutaneous PDT occurs via different mechanisms, a common regulatory point exists.

The anatomic site of photodynamic therapy is a determinant for immunosuppression in a murine model.

The role of the irradiation site in the induction of suppression of the contact hypersensitivity (CHS) response following photodynamic therapy (PDT) was examined in a murine model. Laser irradiation on the flanks of nontumor-bearing Photofrin-injected mice caused suppression of the CHS response. If the irradiation was conducted on a subcutaneously implanted foil disc on the flank no immunosuppression occurred, indicating that no suppressive factor(s) of sufficient quantity to cause suppression was released from the skin, but rather irradiation of internal organs was the cause. Irradiation of tumors implanted on the flanks of mice reduced the suppression, suggesting an immunopotentiating effect of PDT. Irradiation on the thigh in the presence or absence of a tumor gave no immunosuppression. These results suggest that the anatomic site of irradiation is one determinant for the elicitation of suppression of the CHS response.

Altered expression of interleukin 6 and interleukin 10 as a result of photodynamic therapy in vivo.

Photodynamic therapy (PDT), which can effectively destroy malignant tissue, also induces a complex immune response that potentiates antitumor immunity but also inhibits skin contact hypersensitivity (CHS) and prolongs skin graft survival. The underlying mechanisms responsible for these effects are poorly understood but are likely to involve mediation by cytokines. We demonstrate in a BALB/c mouse model that PDT delivered to normal and tumor tissue in vivo causes marked changes in the expression of cytokines interleukin (IL)-6 and IL-10 but not tumor necrosis factor alpha. IL-6 mRNA and protein are strongly enhanced in the PDT-treated EMT6 tumor. PDT also increased IL-6 mRNA in exposed spleen and skin. These data suggest that the general inflammatory response to PDT may be mediated at least in part by IL-6. In addition, IL-6 may modulate the local antitumor immune response. In contrast, IL-10 mRNA in the tumor decreases following PDT. Most importantly, IL-10 is markedly induced in the skin of mice exposed to a PDT regime that strongly inhibits the CHS response, and the kinetics of IL-10 induction coincide with the known kinetics of CHS inhibition. We propose that the enhanced IL-10 expression plays a role in the observed suppression of cell-mediated responses seen following PDT.

Duplex ultrasonography to diagnose failing arterial prosthetic grafts.

BACKGROUND: Although several reports have documented the usefulness of a surveillance program with duplex ultrasonography (DU) to diagnose failing autologous vein bypasses, the effectiveness of DU to detect failing arterial prosthetic grafts has not been confirmed. We attempted to determine whether our program, which included DU and other noninvasive techniques (NonDU), was useful for this purpose. METHODS: Between July 1, 1991, and September 30, 1994, 85 prosthetic bypasses in 59 patients performed for lower extremity ischemia were entered into a graft surveillance protocol. There were 35 femoropopliteal, 16 femorotibial, 15 iliofemoral, 13 axillofemoral, and 6 femorofemoral bypasses. Both DU and NonDU were performed 1 week and every 3 months after the initial bypass or after graft revision. NonDU criteria of a failing graft included changes in symptoms or pulses, decreased ankle/brachial index greater than 0.15, or diminution of ankle pulse volume recordings greater than 50%. Normal grafts were bypasses that had less than 50% stenosis documented by arteriography or remained patent. Problem grafts were those that required revision or thrombosed before intervention. Follow-up of patient grafts ranged between 3 and 36 months (mean, 11 months). RESULTS: DU predicted 17 (81%) of 21 problem grafts versus only 5 (24%) diagnosed by NonDU (p = 0.001). Lesions associated with these 21 grafts were perianastomotic in 10 cases, in adjacent inflow or outflow arteries in 8 cases, and intrinsic to the graft in 3 cases. The likelihood of a graft thrombosing in the presence of a normal test was 7% (4 of 58) for DU compared with 21% (16 of 76) for NonDU (p = 0.04). CONCLUSIONS: DU is more sensitive than NonDU in predicting failure of prosthetic grafts. This study suggests that DU should routinely be performed as part of a surveillance program for peripheral arterial prosthetic bypasses.

Safety and cost-efficiency of 24-hour hospitalization for carotid endarterectomy.

The safety and cost savings of carotid endarterectomy (CEA) were determined with guidelines developed after vascular "critical pathways" were implemented. Using these guidelines, our goal was to admit patients the day of surgery and to discharge them the next morning. Morbidity, mortality, readmission rates, same-day admissions, duration of stay, and hospital costs were compared between patients undergoing CEA who were electively admitted between September 1, 1992 and August 31, 1993 (group 1) and January 1, 1994 and March 31, 1995 (group 2). Between these two time periods, vascular critical pathways were instituted and all preoperative examinations were performed on an outpatient basis. The majority of CEAs were performed with the patient under general anesthesia. We found no significant differences between group 2 (n = 68) vs. group 1 (n = 40) in terms of mortality (1.5% [1 of 68] vs. 2.5% [1 of 40]), cardiac events (2.9% [2 of 68] vs. 2.5% [1 of 40]), neurologic events (2.9% [2 of 68] vs. 2.5% [1 of 40]), or readmission rate (1.5% [1 of 68] vs. 0% [0 of 40]). Same-day admissions were significantly higher (94% [64 of 68] vs. 5% [2 of 40]; p < 0.0001), and average duration of stay was significantly lower (1.3 vs. 5.1 days; p < 0.0001) in group 2 vs. group 1, respectively. Hospital charges were decreased by $5510 per patient in group 2. We conclude that hospital costs can be significantly reduced for most patients undergoing CEA when they are admitted on the day of surgery and discharged the following morning, with no negative impact on morbidity and mortality.

Impact of clinical pathways on hospital costs and early outcome after major vascular surgery.

PURPOSE: The purpose of this study was to determine whether major vascular surgery could be performed safely and with significant hospital cost savings by decreasing length of stay and implementation of vascular clinical pathways. METHODS: Morbidity, mortality, readmission rates, same-day admissions, length of stay, and hospital costs were compared between patients who were electively admitted between September 1, 1992, and August 30, 1993 (group 1), and January 1 to December 31, 1994 (group 2), for extracranial, infrarenal abdominal aortic, and lower extremity arterial surgery. For group 2 patients, vascular critical pathways were instituted, a dedicated vascular ward was established, and outpatient preoperative arteriography and anesthesiology-cardiology evaluations were performed. Length-of-stay goals were 1 day for extracranial, 5 days for aortic, and 2 to 5 days for lower extremity surgery. Emergency admissions, inpatients referred for vascular surgery, patients transferred from other hospitals, and patients who required prolonged preoperative treatment were excluded. RESULTS: With this strategy same-day admissions were significantly increased (80% [145/177] vs 6.2% [9/145]) (p < 0.0001), and average length of stay was significantly decreased (3.8 vs 8.8 days) (p < 0.0001) in group 2 versus group 1, respectively. There were no significant differences between group 1 and group 2 in terms of overall mortality rate (2.1% [3/145] vs 2.3% [4/177]), cardiac (3.4% [5/145] vs 4.0% [7/177]), pulmonary (4.1% [6/145] vs 1.7% [3/177]), or neurologic (1.4% [2/145] vs 0% [0/177]) complications, or readmission within 30 days (11.3% [16/142] vs 9.2% [16/173]) (p > 0.05). There were also no differences in morbidity or mortality rates when each type of surgery was compared. Annual hospital cost savings totalled $1,267,445. CONCLUSION: Same-day admission and early hospital discharge for patients undergoing elective major vascular surgery can result in significant hospital cost savings without apparent increase in morbidity or mortality rates.

The use of tetrazolium salts to determine sites of damage to the mitochondrial electron transport chain in intact cells following in vitro photodynamic therapy with Photofrin II.

A method is described utilizing the tetrazolium salts neotetrazolium chloride (NTC), triphenyltetrazolium chloride (TTC), C,N-diphenyl-N'-4,5-dimethylthiazol-2-yltetrazolium bromide (MTT) and various substrates to elucidate damage to the mitochondrial electron transport chain of intact cells following in vitro photodynamic therapy (PDT). Using this methodology, a portion of the dark toxicity manifested by Photofrin II (PII) was found to occur prior to entry of electrons into the transport chain through Complex I, as evidenced by the fact that the inhibition of MTT reduction was reversible by the addition of malic acid to the culture media. A second site of dark toxicity was found to be Complex IV (cytochrome oxidase). After photoirradiation of the cells, Complex I was found to be affected since malic acid could no longer reverse the inhibition of MTT reduction but it could be reversed by the addition of succinic acid, whose electrons enter the transport chain at Complex II. A second and more sensitive site of photoirradiation damage was found to be Complex IV. A region near cytochrome C was also affected by photoirradiation but appreciably less so than noted for Complexes I and IV. A kinetic analysis of MTT and TTC reduction following photoirradiation indicated that MTT reduction was sustained at a normal rate for 1 h after which it slowed down and eventually plateaued. In contrast, TTC reduction was found to be inhibited almost immediately indicating Complex IV is extremely susceptible to photoirradiation damage. Compared to other assays of mitochondrial function requiring subcellular fractionation, the use of tetrazolium salts is simpler to perform and can be done using physiologically relevant conditions.

Death and adverse cardiac events after carotid endarterectomy.

PURPOSE: This study evaluated operative mortality rate and adverse cardiac events after carotid endarterectomy. Efficacy of preoperative cardiac evaluation was studied and stroke mortality rate was determined. METHODS: This was a retrospective review of 562 patients undergoing carotid endarterectomy at a 740-bed community hospital. Data were analyzed with chi 2 analysis, logistic regression analysis, and Goldman criteria for cardiac risk. RESULTS: The mortality rate was 1.6% (nine patients). There were 10 myocardial infarctions (1.8%). Six of these (1.1%) were fatal. The Goldman Index allowed us to classify 530 patients in a low-risk group (Goldman classes I and II, operative mortality rate = 1.1%) and 32 patients in a high-risk group (Goldman classes III and IV, mortality rate = 9.4%). Independent risk variables were identified for myocardial infarction and overall operative death. These variables were then used to develop a probability model for prediction of operative death and adverse cardiac events. The stroke rate in the 562 patients was 0.7% (four patients). For the 345 patients with symptoms, the stroke rate was 0.6% (two patients); for the 217 symptom-free patients, it was 0.9% (two patients). The combined stroke mortality rate was 2.3%. For patients with symptoms, it was 2.9%; for symptom-free patients, it was 1.4%. CONCLUSIONS: Independent clinical variables can help determine patients at increased risk for perioperative myocardial infarction or operative death. Patients in Goldman classes III and IV are at increased risk for adverse events. Carotid surgery can be performed safely in our medical community.

Laparoscopic colectomy: at what cost?

The purpose of this study was to compare laparoscopic to open colectomy with respect to: 1) morbidity and mortality, 2) adequacy of resection for cancer (margins and number of nodes), 3) operative time, 4) postoperative time for tolerating diet and discharge, and 5) total hospital charges. A historical control group of open colon surgery patients was used. Laparoscopic colectomy was completed in 18/24 patients and 6 were converted to open colectomy. There were no operative or perioperative mortalities. In procedures for cancer, all margins were free of tumor. The average number of nodes in the laparoscopic group (LC) was higher than in open colectomy (OC) group. The average operative time was slightly longer in the LC group compared to the OC group. Postoperative length of stay was shorter in the LC group, and considerably shorter in the elective LC group. Corrected average total hospital cost was lower in the LC group than in the OC group. Laparoscopic colectomy has acceptable morbidity and mortality, is cost-efficient and seems to provide adequate resection for cancer, although long-term data will be crucial to this issue.

Nurse characteristics and professional autonomy.

Relationships between selected demographic characteristics and professional nursing autonomy were examined. Identification of such relationships can strengthen development of the professional nursing role. Usable responses were returned by 542 RNs in a random sample of 2,000 nurses from four states. The Personal Attributes Questionnaire (Spence, Helmreich, & Stapp, 1974) and Nursing Activity Scale (Schutzenhofer, 1987) were used. Significant relationships were noted among autonomy and the following: nursing education, practice setting, clinical specialty, functional role, membership in professional organizations, and gender stereotyped personality traits.

Cutaneous photosensitizing and immunosuppressive effects of a series of tumor localizing porphyrins.

A series of tumor localizing porphyrins was evaluated with respect to their ability to elicit cutaneous photosensitivity and systemic immunosuppression, two of the most common side effects associated with photodynamic therapy. Using the murine ear swelling response as an indicator, it was found that all the non-metalloporphyrins caused cutaneous photosensitization. Immunosuppressive effects were noted using hematoporphyrin derivative (HPD) and meso-tetra(4-sulfonatophenyl)porphine if sensitization occurred immediately after photoirradiation, but none were evident using Photofrin II (PII) or meso-tetra(4-carboxyphenyl)porphine (TCPP). Subsequent studies indicated that PII and TCPP manifested a delayed type immunosuppression similar to that found following UVB photoirradiation. Manganese (III) meso-tetra(4-sulfonatophenyl)porphine, a prototype magnetic resonance imaging contrast agent, was also evaluated because of its reported demetallation in vivo. It was found to cause neither cutaneous photosensitivity nor immunosuppression.

Bilateral femoral nerve neuropathy following blunt trauma. Case report.

A unique case of bilateral compressive injury of the femoral nerves is reported in a 19-year-old man. Traumatic femoral nerve neuropathy following operative injury, penetrating injury, anticoagulant therapy with hemorrhage, and stretch injury has been described previously, and the literature concerning this unusual clinical problem is reviewed. Bilateral traumatic femoral nerve neuropathy resulting from compressive injury has not been previously reported.

A comparative study of manganese meso-sulfonatophenyl porphyrins: contrast-enhancing agents for tumors.

Four manganese meso-sulfonatophenyl porphyrins were prepared, characterized and investigated for their potential as tumor-specific MRI contrast-enhancing agents in mice bearing subcutaneous implants of a mammary carcinoma (SMT-F). The trisulfonated tetraphenyl porphyrin, MnTPPS3 presented the most favorable profile: bio-distribution, tumor concentration and tumor relaxivity, when compared at 24 hr postinjection. Imaging experiments revealed that a time-dependent delineation of tumor morphology occurs in response to MnTPPS3 that appears to correlate with necrotic regions of the tumor.

The effect of photodynamic therapy (PDT) on glucose levels within the SMT-F mouse tumor.

Tumor glucose levels were assessed at various times following in vivo photodynamic therapy (PDT) and compared to levels following induction of anoxia in mice bearing the SMT-F tumor. Uptake of 2-deoxy-D glucose by isolated tumor cells was not altered following in vivo PDT. Tumor glucose levels following PDT were found to decline in a similar albeit slower manner to those found under anoxic conditions for 40 minutes and thereafter they declined at a greater rate. These results suggest an ischemic mechanism of tumor destruction characterized by the progressive development of stasis followed by hemorrhage resulting in the rapid depletion of extracellular glucose.

Mechanism of the localization of manganese (III) mesotetra(4-sulfonatophenyl)porphine in mice bearing L1210 tumors.

In accordance with earlier work the manganese (III) derivative of meso-tetra(4-sulfonatophenyl)porphine (TPPS4) is found to accumulate in the tumors of L1210-bearing mice. The tumor/liver ratio of porphyrin extends from 1.5 to 3.6 over a range of dose and time periods. The subcellular distribution of porphyrin in L1210 tumor and liver, and the tissue distribution (cellular, stroma, soluble) in L1210 tumor indicates that the porphyrin tends to be located predominantly in soluble and stromal fractions. These data are interpreted in terms of the physiology and composition of neoplastic tissue to formalize a mechanism for the localization of Mn(III)TPPS4 in L1210 tumor and a general working hypothesis for the localization of porphyrins in neoplastic tissue. The in vivo stability of Mn(III)TPPS4 is also addressed and is found to be demetallated to a degree of approximately 1% in liver and kidney.

Proton relaxation enhancement by manganese(III)TPPS4 in a model tumor system.

Managanese(III)tetraphenylporphine sulfonate [Mn(III)TPPS4] has been investigated as a tumor specific paramagnetic contrast agent for magnetic resonance imaging (MRI) of L1210 solid tumors in mice. Mn(III)TPPS4 was found to clear rapidly from the blood and concentrate in the kidneys, tumor and liver. Although relatively high ratios of tumor to normal tissues could be obtained (e.g., greater than 90 for tumor/muscle), the kidneys were found to have the highest concentration of the metalloporphyrin at all doses and time periods tested. A significant decrease in the longitudinal relaxation time was measured for excised tissues (kidney, tumor, liver, muscle) from mice that were treated with Mn(III)TPPS4. A linear correlation was observed between the longitudinal relaxation rate determined for L1210 tumor and the corresponding concentration of Mn(III)TPPS4 found at various injected doses and time intervals between the injection and analysis. A small animal radiofrequency receiver coil designed for use with a 0.15-T clinical imager was employed to evaluate the ability of Mn(III)TPPS4 to selectively increase the signal intensity of the implanted L1210 tumor. The images show a conspicuous enhancement in the contrast between the tumor and adjacent tissue upon treatment with this agent. The results indicate that Mn(III)TPPS4 is a useful prototype paramagnetic metalloporphyrin MRI contrast agent with a significant affinity for the L1210 tumor.