The pulsed-dye laser for treatment of cutaneous conditions.

The concept of selective photothermolysis simply states that if one heats target tissue with a laser that is selectively absorbed by that tissue, heat should last sufficiently enough to cause damage to the target tissue, but not so long for the heat to spread to the surrounding tissue. The pulsed-dye laser (PDL) was the first laser to utilize the concept of selective photothermolysis to treat dermatologic conditions. The first application of this concept was directed at treating port-wine stain birthmarks (PWSs). A myriad of conditions that were previously only marginally treated by earlier-generation PDLs could be addressed, increasing by a factor of many thousand the number of potential patients for PDL treatment. Rosacea, scars, red striae, some lower-extremity spider veins, and photodamage could now be easily treated in addition to PWSs, nevus araneuses, cherry hemangioma, and verrucae. Finally, the latest advances in PDL technology have maximized the ability to treat linear vessels such as lower-extremity spider veins, and linear facial vessels associated with rosacea, photodamage or simply heredity, as well as improving the ability to treat diffuse erythema such as the facial redness of rosacea, PWSs, scars and striae with less risk of epidermal damage and hyperpigmentation. Final advances aim to reduce side-effects of both types of vascular lasers while potentially increasing benefits by allowing the delivery of higher fluencies. Cooling the surface of the skin protects melanin pigment while allowing the delivery of light to the dermis to remove unwanted blood vessels and potentially stimulate dermal remodeling.

Expression of fibrinolytic genes in atherosclerotic abdominal aortic aneurysm wall. A possible mechanism for aneurysm expansion.

Expansion of atherosclerotic abdominal aortic aneurysm (AAA) has been attributed to remodeling of the extracellular matrix by active proteolysis. We used in situ hybridization to analyze the expression of fibrinolytic genes in aneurysm wall from eight AAA patients. All specimens exhibited specific areas of inflammatory infiltrates with macrophage-like cells expressing urokinase-type plasminogen activator (u-PA) and tissue-type PA (t-PA) mRNA. Type 1 PA inhibitor (PAI-1) mRNA was expressed at the base of the necrotic atheroma of all specimens and also within some of the inflammatory infiltrates where it frequently colocalized in regions containing u-PA and t-PA mRNA expressing cells. However, in these areas, the cellular distribution of the transcripts for t-PA and u-PA extended far beyond the areas of PAI-1 expression. These observations suggest a local ongoing proteolytic process, one which is only partially counteracted by the more restricted expression of PAI-1 mRNA. An abundance of capillaries was also obvious in all inflammatory infiltrates and may reflect local angiogenesis in response to active pericellular fibrinolysis. The increased fibrinolytic capacity in AAA wall may promote angiogenesis and contribute to local proteolytic degradation of the aortic wall leading to physical weakening and active expansion of the aneurysm.

A novel in vivo model for evaluating agents that protect against ultraviolet A-induced photoaging.

Increasing evidence demonstrates that ultraviolet A radiation (UVA) contributes to photoaging, which results in the accumulation of massive amounts of abnormal elastic material in the dermis of photoaged skin. To study UVA-induced photoaging in an in vivo system, we utilized a line of transgenic mice containing the human elastin promoter linked to a chloramphenicol acetyl transferase reporter gene. Our prior work demonstrates promoter activation in response to ultraviolet B radiation (UVB), UVA, and psoralen plus ultraviolet A radiation in the skin of these mice. The addition of psoralen (8-MOP) prior to administration of UVA results in substantial increases in promoter activation, as compared with UVA alone. To demonstrate the utility of these mice as a model of UVA-induced photodamage, we administered four lotions to the skin of our transgenic mice that included: a sunscreen containing octyl methoxycinnamate and benzophenone-3 with a sun protection factor (SPF) of 15, the UVA filter butyl methoxydibenzoylmethane, the SPF 15 sunscreen and the UVA filter together, and the lotion vehicle alone. Following sunscreen administration, mice received a single psoralen plus ultraviolet A radiation treatment. All sunscreens decreased chloramphenicol acetyl transferase activity with the SPF 15 sunscreen, the UVA filter, and the combination SPF 15 sunscreen and UVA filter, resulting in increasing degrees of protection against psoralen plus ultraviolet A radiation. These results demonstrate that this model functions as a rapid and sensitive model of UVA photodamage for the identification and comparison of compounds that protect against UVA-induced photoaging.

Transforming growth factor-beta improves healing of radiation-impaired wounds.

Exogenously applied TGF-beta 1 has been shown to increase wound strength in incisional wounds early in the healing process. An impaired wound healing model was first established in guinea pigs by isolating flaps of skin and irradiating the flaps to 15 Gray in one fraction using a 4-MeV linear accelerator. Incisions made 2 d after irradiation were excised 7 d later, and showed decreased linear wound bursting strength (WBS) as compared to non-irradiated control wounds on the contralateral side of each animal (p = 0.001). The effect of TGF-beta on healing of radiation-impaired wounds was studied using this model. Skin on both left and right sides of guinea pigs was irradiated as above. A linear incision was made in each side. Collagen with either 1, 5, or 20 micrograms of TGF-beta was applied to one side prior to closure with staples, whereas the contralateral side received saline in collagen. Wounds given either 1 or 5 micrograms of TGF-beta were found to be stronger than controls at 7 d (p less than 0.05), whereas those receiving the higher 20-micrograms dose were weaker than controls (p less than 0.05). Thus, TGF-beta in lower doses improved healing at 7 d but very large amounts of the growth factor actually impaired healing. In situ hybridization done on wound samples showed increased type I collagen gene expression by fibroblasts in wounds treated with 1 micrograms TGF-beta over control wounds. These results indicate that TGF-beta improved wound healing as demonstrated by increased WBS. This improvement is accompanied by an up-regulation of collagen gene expression by resident fibroblasts.

Ultraviolet radiation activates the human elastin promoter in transgenic mice: a novel in vivo and in vitro model of cutaneous photoaging.

The major alteration in photoaged skin is the deposition of massive amounts of abnormal elastic material, termed solar elastosis. In previous work, it has been shown that solar elastosis is accompanied by increased abundance of elastin and fibrillin mRNAs and upregulation of elastin promoter activity. Using a transgenic mouse line, which expresses the human elastin promoter, linked to a chloramphenicol acetyltransferase reporter gene, in a tissue-specific and developmentally regulated manner, we investigated the effects of ultraviolet A radiation and ultraviolet B radiation on human elastin promoter activity in vivo and in vitro. Irradiation of mice with a single dose of ultraviolet B radiation (491.4 mJ/cm2) resulted in an increase up to 8.5-fold in promoter activity, whereas a more modest increase of 1.8-fold was measured with ultraviolet A radiation (38.2 J/cm2). In addition, in vitro studies revealed over a thirtyfold increase in elastin promoter activity in response to ultraviolet B radiation (5.5 mJ/cm2), whereas no change was measured in response to ultraviolet A radiation (2.2 J/cm2). These results confirm the role of ultraviolet B radiation in elastin promoter activation in photoaging, and identify ultraviolet A radiation as a contributing factor. This system should serve as a useful in vivo and in vitro model to study cutaneous photoaging, and for testing compounds that may protect against cutaneous photodamage.

Enhanced elastin and fibrillin gene expression in chronically photodamaged skin.

Cutaneous aging consists of chronologic aging as well as actinic damage, referred to as photoaging. Most of the morphologic changes associated with an aged appearance result from actinic damage to the skin. The morphologic changes in sun-damaged skin are associated with accumulation of material having the staining characteristics of elastin, known as solar elastosis, in the superficial dermis. Previous studies have demonstrated the presence of elastin within areas of solar elastosis; however, little is known about the mechanisms leading to elastin accumulation in photoaged skin. In addition, fibrillin, the fibrillar component of elastic fibers, has been found in small amounts in solar elastosis. In this study we demonstrate increased elastin mRNA levels in photoaged skin, as well as increased elastin and fibrillin mRNAs in skin explant-derived fibroblasts using Northern hybridizations, compared with controls from sun-protected sites of the same individual. Increased elastin mRNA levels result from transcriptional upregulation of the gene, as demonstrated by transient transfections with a human elastin promoter/chloramphenicol acetyltransferase construct. Elevated mRNA levels were also correlated with increased elastin and fibrillin deposition in paired biopsy specimens from photodamaged and non-sun-exposed skin, as demonstrated by immunohistochemical staining. Thus, approaches to counteract transcriptional activation of elastin gene expression may be useful in preventing the changes associated with cutaneous photoaging.

A diffusing sphere which delivers homogeneous laser light for use in photodynamic therapy.

Photodynamic therapy (PDT) exploits the selective uptake of a photosensitizer in tumors and other hyperproliferative target tissues, as well as the ability to direct the treatment light beam to a specific region. Since the photodynamic effect depends on light dose, tissue optical properties and photosensitizer concentration, uniform delivery of light is crucial to attain optimal photodynamic effect. Many commonly used methods for delivering laser light during photodynamic therapy, such as a free fiber or microlens, require fiber and laser adjustments to obtain a highly uniform beam. In this study, we test the ability of a diffusing sphere to improve the uniformity of a light field coming from an argon laser coupled to a free fiber, in which no attempt has been made to optimize beam characteristics. Light fields from the free fiber, a microlens and the diffusing sphere are compared for uniformity via light intensity readings. An in vivo comparison between the sphere and the free fiber is also made in guinea pigs given Photofrin-II. The diffusing sphere decreases problems with shielding, allows quick and easy application of light by simply applying the device over the desired treatment area, and optimizes the desired photodynamic effect by producing ad highly uniform beam of light with no necessity to optimize light delivery by vibrating, looping or re-cleaving fibers.

The importance of combined multisegmental pressure and Doppler flow velocity studies in the diagnosis of peripheral arterial occlusive disease.

The value of combined multisegmental pressures and quantitative Doppler flow velocity determinations in the preoperative vascular laboratory evaluation was analyzed in 100 consecutive patients with angiographically documented peripheral arterial occlusive disease. Several new observations were made: (1) erroneously normal or even high segmental pressure readings appear to be caused by increased arterial wall stiffness and may produce falsely elevated or erroneously normal pressure, suggesting less disease than exists, especially when only ankle pressure screening is used. (2) The addition of quantitative flow velocity determinations significantly improved the reliability of diagnostic decision making. The diagnosis of proximal arterial occlusive disease based on combined pressure-velocity measurements was confirmed angiographically in 143 of 148 limb studies (96.6%), including several with normal pressures and reduced velocity values--a pressure-velocity dissociation. (3) A decrease of the leg segment:arm pressure ratio combined with only a slight reduction of velocity indices suggests a stenosis with good local collateral flow and vessel patency at the site of measurement--a reversed pressure-velocity dissociation. (4) A decreased lower limb segment/arm pressure ratio combined with a significant reduction of velocity indices is evidence of arterial stenosis with poor local collateral flow. The combined multisegmental pressure and velocity evaluation of patients suspected of arterial occlusive disease substantially increases the reliability of noninvasive diagnosis and offers a new level of differential diagnostic interpretation.

The pulse-reappearance time: an index of over-all blood flow impairment in the ischemic extremity.

A simple test is described to evaluate limb blood supply. The technique utilizes the delayed reappearance of the volume pulse after transient arterial occlusion. As monitored from the toe by a mercury-in rubber gauge, pulse reappearance (PRT) was instantaneous (less than one second) and the 50 percent of control amplitude reappearance time (PRT/2) was 3.4 +/- 0.8 seconds in 22 control subjects. A significant delay of the PRT and especially of PRT/2 was found in 60 patients with angiographically documented ischemic disease of the lower extremities. The delay was correlated closely with the severity of the disease: the mean PRT/2 for single level arterial disease (aortoiliac, femoropopliteal, posterior tibial, or anterior tibial artery obstruction) was approximately 25 seconds, and the mean PRT/2 associated with multilevel occlusion was 71 seconds. Since the technique is very simple, it may be used as a quick screening and follow-up procedure to detect the presence and over-all severity of peripheral arterial occlusive disease.

Thigh pressure artifacts with noninvasive techniques in an experimental model.

In an experimental canine model of isolated and tandem arterial stenoses, noninvasive thigh and calf pressure measurements were evaluated against direct intra-arterial pressures. Under control circumstances, proximal iliac arterial stenosis, and high superficial femoral artery stenosis, the noninvasive measurements were highly accurate. However, when stenoses were created distal to the high pressure cuff, a significant error in the thigh pressure measurement was observed, with an underestimation of thigh pressure and subsequent false implication of a proximal lesion. Two tandem distal lesions produced a significantly more severe thigh measurement artifact. Further, the noninvasive system was incapable of detecting a moderately severe profunda stenosis, although stenoses of the iliac and femoral system were detected in a routine, accurate, and sensitive fashion.

The effects of pulseless perfusion on the distribution of renal cortical blood flow and on renin release.

The effects of pulseless perfusion on the distribution of renal blood flow and on release of renin were studied in anesthetized dogs. The distribution of renal blood flow to four cortical layers was determined with the radioactive microsphere technique during pulsatile control conditions and after one and 2 hours of pulseless perfusion, without significant changes in mean arterial pressure and mean total renal blood flow. Simultaneously, renal vein blood samples were analyzed for renin (radioimmunoassay technique). During pulseless perfusion there was a consistent and progressive redistribution of blood flow toward deeper cortical layers with the outer cortical layer falling from 36.9 to 25.3% p less than 0.001) and the juxtamedullary cortex increasing from 14.5 to 25.4% (p less than 0.001) after 2 hours. In addition, there was a progressive increase in renal venous concentration of renin, which was 20.91 +/- 6.6 ng. per millimeter per hour after 2 hours of pulseless flow compared to 5.06 +/- 1.16 ng. per millimeter per hour during control conditions (p less than 0.05). These changes in cortical blood flow and in release of renin were not observed in sham-operated controls. The results indicate that pulseless flow alone produced both a significant increase in renal production of renin and a significant redistribution of renal cortical blood flow, due to the greater vasoconstriction in the outer cortex when compared to the juxtamedullary cortex.

Axillary, subclavian, and brachiocephalic vein obstruction.

The consequences of occlusion of a major upper extremity vein were evaluated in eight patients with effort thrombosis, ten with thrombosis secondary to intimal injury, six with extrinsic compression, and one hypercoagulable patient, all of whom were followed for an average of 4 years. Twenty-two patients had venography, which confirmed the diagnosis but often failed to define the proximal extent of obstruction. Thirteen patients had noninvasive hemodynamic studies which did not corroborate chronic morbidity, but which were valuable in assessing the effect os specific therapy. Twelve patients were treated with anticoagulants, and six had operative removal or bypass of the obstruction. Three patients had pulmonary emboli; two embolized while on anticoagulants and both died. Swelling, pain, prominent veins, and easy fatigability of the affected extremity were the late sequelae of occlusion. Chronic morbidity was more dependent on etiology than on initial treatment. Thrombosis secondary to intimal injury caused no persistent symptoms, whether treated with anticoagulants or not. Effort thrombosis was intermediate: three fourths complained that their affected arm tired easily and half had prominent veins or persistent swelling. All of those with obstruction secondary to extrinsic compression had easy fatigability. The majority also had concomitant swelling, pain, and prominent collaterals. Operative treatment produced objective improvement in venous outflow but often was unsuccessful in relieving symptoms, particularly in patients with obstruction from extrinsic compression.

Growth rates of small abdominal aortic aneurysms.

A policy of utilizing B-mode ultrasound scan measurements of abdominal aortic aneurysms to help determine operability in poor-risk patients with small asymptomatic aneurysms has been pursued for the past 6 years. Indications for surgery in such patients have included enlargement to 6 cm. in any transverse diameter, the development of symptoms, or evidence of leak or rupture. In addition, patients treated nonoperatively have been followed by serial B-mode echo scans, permitting the accumulation of aneurysm growth rate data. Such data indicate that small aneurysms grow an average of 0.4 cm. per year, but that dramatic increases in aneurysm size may occur unexpectedly in asymptomatic patients. These data appear to have value in both individual decision making and as a baseline for weighting the various risk factors in the poor-risk patient with a small asymptomatic abdominal aortic aneurysm.

Acute physiologic effects of arteriovenous anastomosis and fistula in revascularizing the ischemic canine hind limb.

In a severe, diffuse arterial occlusion model of canine hind-limb ischemia, both distal arteriovenous fistula (AVF) and arteriovenous end-to-side anastomosis (AVA) were evaluated as potential methods of revascularization. AVA reversed or minimized both hemodynamic and metabolic indices of ischemia; AVF did not. After AVA segmental blood pressures at the thigh returned to normal, and those at the calf returned to 0.8 from an ischemic level of 0. Both postocclusion toe pulse reappearance times and the toe pulse volumes partially returned toward normal. IN addition, gastrocnemium intramuscular Po2 returned from an ischemic level of 5.3 to 45.5 mm Hg, compared to a control normal of 47.6 mm Hg. Muscle surface pH returned to 7.40 from the ischemic level of 7.06. AVA appears to offer an approach to the treatment of severe, diffuse arterial disease that would utilize the distal venous tree to transport blood to the capillaries for the support of adequate tissue nutrition.

Transcutaneous PO2 measurements in health and peripheral arterial occlusive disease.

Transcutaneous oxygen tensions (tcPO2) of the lower extremity were investigated in 24 control subjects and in 69 patients with various degrees of peripheral arterial occlusive disease. With a modified Clark-type oxygen electrode, tcPO2 was monitored from the right subclavicular region (position 1), upper calf (position 2), and dorsum of the foot (position 3). The tcPO2 was significantly lower in patients when compared to control subjects. The reproducibility of the method was determined from double determinations of the tcPO2 (position 2) in control subjects. The comparison of tcPO2 value between the right and left lower extremity showed no significant differences. The tcPO2 of the foot or leg showed an increase, when positioning the limb below the phlebostatic level. The response of the tcPO2 after transient arterial occlusion (4 minutes) was significantly delayed in patients compared to control subjects. Finally, preliminary results of 35 patients in whom amputations had been performed suggest that tcPO2 measurement may become a useful prognosticator for the determination of the optimal amputation level.

Valve competence following experimental venous valve autotransplantation.

In canine experiments, venous patency and valvular competence were evaluated following transposition of a valve-containing vein segment, with an without a distal arteriovenous (AV) fistula. The effects of distal fistula size on valvular function were also examined. Autogenous valve-containing venous segment grafts were placed in the femoral position. With no adjuncts, 90% of the grafts showed either occlusion, severe extrinsic narrowing, or intraluminal filling defects on early venograms, although 75% of valves were eventually competent at death. Veins that had undergone thrombosis and recanalization were routinely incompetent. With a distal AV fistula, all veins remained patent and 86% demonstrated valve competence. With both an AV fistula and dextran 40, all veins remained patent and all valves were component. Separately, graded size of AV fistulas did not result in loss of valve competence. Following venous segment transposition, continuous venous patency appears necessary for eventual valvular function, and this is enhanced by both a distal AV fistula and dextran.

Quantitative transcutaneous arterial velocity measurements with Doppler flowmeters.

A controlled in vitro and in vivo comparative evaluation of four Doppler ultrasonic blood velocimeters was performed to evaluate their ability to measure fluid velocity throughout a wide range of flow rates and velocity profiles, during both steady and pulsatile flow. The instruments tested were the Versatone Bidirectional Doppler M-9, the Sonicaid BV380, the Parks 806 B, and the Delalande DUD 400. All instruments responded linearly to velocities of from 5 to 70 cm/s, and were accurate to within 5% through a wide range of in vitro changes in velocity, pulse frequency, and cross-sectional velocity profile. Quantitative velocity measurements and their derivatives are an inexpensive, simple, and useful tool in the evaluation conditions of patients with peripheral vascular disease, and widespread clinical trials of their value are appropriate at this time.

The effect of sensing site on the limb segmental blood pressure determination.

The effect of the sensing site on upper-thigh blood pressure readings was studied. We used a multisensing mercury strain gauge (MSG) plethysmographic method and Doppler ultrasound to monitor the upper-thigh blood pressure from the posterior tibial artery and compared the results with those from the popliteal artery. Upper-thigh pressures were measured in 30 limbs of 15 normal subjects and in 60 limbs of 35 patients with multilevel peripheral arterial occlusive disease. Upper-thigh pressures sensed from a thigh MSG placed just distally to the pressure cuff and monitored by the popliteal artery Doppler probe were significantly higher than the upper-thigh pressure readings obtained from an MSG placed on the calf or toe and monitored by a posterior tibial artery Doppler probe in patients with multilevel arterial lesions. In the control group, no significant pressure differences were found. The importance of placing the sensor (MSG or Doppler probe) close to the pressure cuff is critical to obtain accurate thigh pressures in patients with multilevel arterial occlusive disease. Otherwise, erroneous diagnoses, such as nonexistent aortiliac or common femoral artery stenosis, may be made.

Utility of computed tomography for surveillance of small abdominal aortic aneurysms. Preliminary report.

To assess the ability of computed tomography to predict the potential for expansion of small abdominal aortic aneurysms, we analyzed the computed tomographic scans of 30 patients who had two or more abdominal computed tomographic scans at least 6 months apart between 1979 and 1989. Clinical variables and 10 defined objective characteristics of computed tomography were evaluated. Twenty-five men and five women with abdominal aortic aneurysms ranging from 30 to 64 mm (mean, 45 mm) were followed up with serial computed tomographic scans for a mean (+/- SE) of 26 +/- 3 months. In 19 patients, enlargement of aneurysm diameter of 3 mm or more on serial computed tomographic scans was noted, whereas in 11, there was little or no expansion. Of the clinical variables studied, only serum cholesterol correlated with an increased risk of expansion. Thrombus area, measured by computed tomography, was 7.3 +/- 0.9 cm2 in enlarging aneurysms vs 4.3 +/- 0.9 cm2 in stable aneurysms. Based on these preliminary data, we conclude that computed tomography may provide valuable information about the likelihood of future expansion of small abdominal aortic aneurysms.

Prognosis of asymptomatic ulcerating carotid lesions.

To determine the proper approach to asymptomatic carotid bifurcation ulcerated plaque (UP), 79 patients with 91 asymptomatic UPs were identified angiographically, and a 96% follow-up was obtained with a mean duration of three years. The cumulative stroke rate by life-table analysis was 1% at seven years. Sixty-three UPs in 55 patients were classified as small, and of these patients, transient ischemic attacks (TIAs) that were appropriate to the lesion developed in three and stroke in one (7% cumulative symptom rate). Twenty-four UPs in 21 patients were classified as large, and a TIA developed in one patient (9%), but no strokes were observed in this group. The cumulative mortality was 17% at three years and 52% at seven years. Life-table curves of several subgroups were compared and showed no significant differences in either stroke rate or mortality between any of these groups. On the basis of these data, and particularly the seven-year stroke rate of 1%, prophylactic carotid endarterectomy is not justified for asymptomatic carotid bifurcation ulcerations.