Biomedical subjects

Y Tadir

Publications and source records attributed to Y Tadir.

At least 19 recordsLinked to original sources

PubMed1998

Laser scissors and tweezers.

In summary, we described the use of laser scissors and tweezers from three perspectives: (a) the historical background from which these two techniques evolved, (b) an understanding and lack of understanding of the mechanisms of interaction with the biological systems, and (c) the applications of the scissors and tweezers alone and in combination. As the technology improves and we gain a better understanding of how these two tools operate they will become even more useful in probing cell structure and function, as well as practically manipulating cells in genetics, oncology, and developmental biology.

Animals↗

PubMed1998

In vivo detection of metastatic ovarian cancer by means of 5-aminolevulinic acid-induced fluorescence in a rat model.

STUDY OBJECTIVES: To determine the feasibility of macroscopic visualization of small ovarian cancer metastases in vivo by fluorescence after intravenous administration of 5-aminolevulinic acid (ALA); to assess the time after drug injection when fluorescence of small metastases is maximum; and to correlate macroscopic in vivo fluorescence with both microscopic ex vivo fluorescence and histologic findings. DESIGN: Controlled animal study (Canadian Task Force classification I). SETTING: University-based facility. SUBJECTS: Twenty-four healthy, female Fischer rats. INTERVENTION: Diffuse peritoneal metastatic cancer was induced in Fischer 344 rats by intraperitoneal injection of 1 million syngeneic ovarian cancer cells (NuTu-19). Four weeks after induction ALA100 mg/kg was injected intravenously, and diagnostic laparotomy was performed 1, 3, 6, or 9 hours thereafter. MEASUREMENTS AND MAIN RESULTS: The peritoneal cavity was illuminated with the Wood's lamp (ultraviolet light). Fluorescence was determined by direct visualization and compared with a calibrated fluorescent disk. Tissues were collected, sectioned, and examined by fluorescence and conventional light microscopy. Within 1 to 3 hours after intravenous injection of ALA, in vivo fluorescence of tumor nodules (diameter 0.4-5.0 mm) was macroscopically visible. Tumor-free peritoneum did not show fluorescence and was significantly distinguishable from cancer nodules. Fluorescence from intestinal tissues was comparable with tumor nodules. Microscopic fluorescence analysis showed similar values for tumor nodules and peritoneum. Stained histologic specimens of peritoneal surface revealed a superficial layer of cancer cells responsible for fluorescence. The time course of the fluorescence curve in the intestine peaked twice, at 1 and 6 hours after ALA injection. Macroscopically fluorescing nodules were histology confirmed as malignant. CONCLUSIONS: Fluorescence detection of small cancer nodules after intravenous injection of ALA is feasible for nodules smaller than 0.5 mm on the peritoneum. One to 3 hours after drug injection is optimal for diagnosis of metastases.

Aminolevulinic Acid↗

PubMed1997

Photodynamic therapy using topically applied dihematoporphyrin ether in the treatment of cervical intraepithelial neoplasia.

OBJECTIVE: To perform a phase I study of topically applied dihematoporphyrin ether (DHE) in the photodynamic treatment (PDT) of cervical intraepithelial neoplasia (CIN) using fixed DHE doses and application schedules, and a variable dose of 630 nm red light delivered by an argon-pumped dye laser. METHODS: Between February 1993 and April 1994, 24 nonpregnant women with a histologic diagnosis of CIN were enrolled. All patients had lesions involving at least 25% of the cervix that were colposcopically visible. Using a cervical cap, 2 ml of a 1% solution of DHE (Photofrin) in a 4% Azone and isopropyl alcohol vehicle were applied to the cervix 24 hr prior to PDT. An argon-pumped dye laser providing light at 630 nm was then used to perform PDT. Light was coupled into a 400-microm silica fiber optic terminating in a microlens which focused the laser radiation onto a circular field of uniform light intensity perpendicular to the tissue. The entire ectocervix was treated in a single field including a margin of 3-5 mm of normal cervix. Using a constant power density (150 mW/cm2) to avoid thermal injury, the PDT energy was increased every 4 patients in a phase I fashion (40, 60, 80, 100, 120, and 140 J/cm2). RESULTS: Thirteen patients with CIN I, 7 patients with CIN II, and 4 patients with CIN III were treated. The maximal energy density was well tolerated. Toxicity was minimal with no patients experiencing local necrosis, sloughing, or scarring; however, a mild vaginal discharge was noted in several patients. Systemic effects were absent. After 12 months of follow-up at 3-month intervals, 22 patients are evaluable of whom 15 (68%) are disease free. One patient was lost to follow-up and in another the cervical cap was dislodged. Four of the 7 failures or recurrences occurred at energy densities of 80 J/cm2 or less, while 8 of 11 (73%) patients were treated successfully with PDT at an energy density of 100 to 140 J/cm2. CONCLUSIONS: PDT with DHE and an argon-pumped dye laser at 630-nm wavelength delivering an energy density of 140 J/cm2 is safe and effective in treating CIN. Phase II studies using PDT at the prescribed application schedule and dose are indicated.

Administration, Topical↗

PubMed1997

In vivo fluorescence detection of ovarian cancer in the NuTu-19 epithelial ovarian cancer animal model using 5-aminolevulinic acid (ALA).

The purpose of this study was to determine whether in vivo fluorescence detection of protoporphyrin IX (PpIX) could be used to identify intraperitoneal micrometastases of epithelial ovarian carcinoma after application of 5-aminolevulinic acid (ALA). ALA was applied intraperitoneal at different concentrations (25, 50, and 100 mg/kg) and iv (100 mg/kg) to immunocompetent Fischer 344 rats bearing a syngeneic epithelial ovarian carcinoma. At different time intervals after ALA administration (1.5, 3, and 6 hr) the peritoneal cavity was illuminated with ultraviolet (uv) light. In vivo fluorescence of PpIX initially was determined by direct visualization. Subsequently ex vivo measurements were made with a slow-scan, thermoelectrically cooled CCD camera. Red in vivo fluorescence was observed in ovarian micrometastases smaller than 0.5 mm in 100% of the ALA-administered animals independent of time interval, drug concentration, or route of administration. The intensity of the fluorescence was concentration dependent as strong fluorescence was consistently found only above 25 mg/kg ALA. Ex vivo tumor to peritoneum fluorescence yield peaked 3 hr after administration of a 100 mg/kg intraperitoneal dose. Direct visualization of in vivo fluorescence after ALA application may improve the detection of intraperitoneal ovarian cancer micrometastases.

Aminolevulinic Acid↗

PubMed1997

Comparison of Ho:YAG versus Nd:YAG thoracoscopic laser treatment of pulmonary bullae in a rabbit model.

OBJECTIVE: To determine the relative efficacy and morbidity of Ho:YAG versus Nd:YAG laser treatment of bullous lung disease in an animal model. SUMMARY BACKGROUND DATA: Laser coagulation procedures for treatment of emphysematous pulmonary bullae and heterogeneous emphysema continue to evolve. The role of lasers in lung volume reduction surgery remains controversial due to issues of relative efficacy and morbidity. The Nd:YAG laser is most commonly used for these procedures. We hypothesized that the shallower penetration of the Ho:YAG laser may be better suited for laser bullae coagulation and emphysema lung volume reduction with increased efficacy and reduced lung injury. METHODS: Thirty New Zealand White rabbits (15 normal rabbits; 15 with bullous lung disease) were evaluated with Ho:YAG compared to Nd:YAG laser exposures. Bullae were coagulated by either Ho:YAG or Nd:YAG treatment. In all animals (bullous-induced and normals), unaffected lung tissue in the upper lobes and contralateral lungs were treated with 5 spot exposures of Nd:YAG and Ho:YAG, each to assess depth of lung injury. Animals were sacrificed at Days 0, 7, and 21 and their lungs were examined histologically. RESULTS: Ho:YAG and Nd:YAG exposures caused equivalent lung injury to normal lung tissue. In the acute phase, parenchymal necrosis depth was similar for both Ho:YAG and Nd:YAG (850 +/- 273 microns vs. 900 +/- 270 microns respectively, p = 0.7). By Day 7, lung necrosis depth was 925 +/- 133 microns Ho:YAG vs. 1225 +/- 235 microns Nd:YAG (p = 0.33), and lung fibrosis depth was 300 +/- 134 microns Ho:YAG vs. 558 +/- 127 microns Nd:YAG (p = 0.11). By Day 21, pulmonary parenchymal necrosis was not seen. Pleural fibrosis depth was maximal at Day 21, reaching 250 +/- 102 microns for Ho:YAG vs. 300 +/- 156 microns Nd:YAG (P = 0.88). Pleural necrosis depth was 67 +/- 42 microns Ho:YAG vs 48 +/- 34 microns Nd:YAG (p = 0.42) on Day 7 and resolved by Day 21. During surgical coagulation procedures, the Ho:YAG laser was dramatically more efficient in coagulating bullae. The Ho:YAG laser required less exposure at equivalent power and resulted in immediate desiccation of bullae, in sharp contrast to the Nd:YAG laser. CONCLUSIONS: Because the Ho:YAG was more effective and did not result in more acute lung injury than the standard Nd:YAG laser in this study, Ho:YAG lasers may have improved potential for laser treatment of bullae or lung volume reduction surgery (LVRS) compared to Nd:YAG lasers.

Animals↗

PubMed1996

Accumulation of 5-aminolevulinic acid-induced protoporphyrin IX in normal and neoplastic human endometrial epithelial cells.

The aim of this study was to evaluate 5-Aminolevulinic acid (ALA)-induced fluorescence of normal and neoplastic endometrial epithelial cells for diagnosis and photodynamic treatment. Fluorescence of ALA-induced PpIX in vitro was measured by flow cytometry in two different human endometrial adenocarcinoma cell lines and in normal cells cultivated from fresh endometrial tissue of three premenopausal patients. The cells were analysed after incubation with different concentrations of ALA during 3, 6, or 24 hours. Both tumor cell lines showed a statistically significant higher fluorescence of PpIX than normal epithelial cells after incubation with 1 mg ALA per ml medium during 24 hours. The well-differentiated cancer cells produced significantly more PpIX than the poorly differentiated cancer cells. Relative PpIX intensity of the two cancer cell lines correlated with cell proliferation rate as measured by the doubling times of the cells. Higher accumulation of Pp IX in neoplastic endometrium compared to normal endometrial epithelial cells may provide targeted biopsies and selective photodynamic destruction of neoplastic micro-lesions.

Adenocarcinoma↗

PubMed1996

Dosimetry model for photodynamic therapy with topically administered photosensitizers.

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) based on topical application of photosensitizers has been under development over the last years. Typical applications are treatment of basal cell carcinoma of the skin and photoablation of the endometrium. The dosimetry for topically administered photosensitizers must take a time-dependent inhomogenous drug distribution into account together with the conventional parameters such as optical scattering, absorption, and photobleaching. STUDY DESIGN/MATERIALS AND METHODS: This study presents a dosimetry model where the cytotoxic dose is calculated in a stepwise procedure. The first step calculates the time-dependent distribution of 5-aminolevulinic acid (5-ALA) from diffusion theory. In skin this distribution is dependent on drug permeability through the stratum corneum, on the diffusivity of dermis and epidermis, on the drug clearance time, and on the conversion rate from 5-ALA to protoporphyrin IX (PpIX). In the second step the distribution of PpIX is calculated from the 5-ALA distribution found in the first step taking the dynamics of the biosynthesis of 5-ALA to PpIX and the clearance time of PpIX into account. In the third step the generation of cytotoxic singlet oxygen is calculated from the optical distribution during irradiation, taking a photobleaching mechanism into account. RESULTS: The distribution of cytotoxic oxygen is predicted from the optical dose, the drug dose, and the time between the application of the drug and the irradiation. CONCLUSION: The presented dosimetry model is made as simple as possible, yet composite enough to enable all relevant parameters to be taken into account. The model that is based on a linear theory in a semi-infinite medium can, if required, be extended to take nonuniform and nonlinear phenomena into account.

Administration, Topical↗

PubMed1996

Animal model for thoracoscopic laser ablation of emphysematous pulmonary bullae.

BACKGROUND AND OBJECTIVE: Thoracoscopic laser techniques have been described for treatment of pulmonary bullae. Clinical application of this procedure has proliferated despite limited data regarding efficacy or optimal techniques. The objective of this study was to develop an animal model for investigating laser treatment of bullous lung disease. STUDY DESIGN/MATERIALS AND METHODS: Sixty-two New Zealand White rabbits (3-5 kg) were injected intravenously with 0.35 cc sterile-filtered Sephadex G-100 beads (1 g/100 cc suspension). Three hours later, rabbits were anesthetized, intubated, and 10 cc 0.7% heat-treated or 1% untreated carrageenan solution was instilled endotracheally into a catheter wedged in a mainstem bronchus. RESULTS: Bullae formed over 4-6 weeks in 33% of the animals treated with 0.7% heat-treated carrageenan, and 90% of animals receiving 1% untreated carrageenan (P < 0.005) as demonstrated by serial thoracoscopy. Thoracoscopy was performed at 6-8 weeks using 5 mm trocars under general anesthesia and mechanical ventilatory support. Animals developed pulmonary bullae ranging in size from 0.5 to 2 cm. Bullae were ablated under thoracoscopic visualization using a CO2 laser with a 4 mm OD rigid probe and short focal length in a defocused mode, or an Nd:YAG laser with a 0.4 mm diameter flexible fiberoptic probe. Animals recovered quickly following thoracoscopy. CONCLUSION: We have successfully developed an animal model for thoracoscopic laser ablation of emphysematous pulmonary bullae. This animal model should be useful in investigating treatment of bullous lung disease in humans.

Animals↗

PubMed1996

Photosensitization of the rat endometrium following 5-aminolevulinic acid induced photodynamic therapy.

BACKGROUND AND OBJECTIVE: The impact of photodynamic therapy (PDT) on the endometrium following topical application of 5-aminolevulinic acid (ALA) was studied in a rat model. Study Design/ MATERIALS AND METHODS: Fluorescence microscopy revealed peak ALA to protoporphyrin IX (Pp IX) conversion 3-6 hours after application. Significantly higher Pp IX levels were observed in the endometrial glands compared with endometrial stroma and myometrium. RESULTS: Histological studies showed PDT-induced endometrial destruction with atrophy 7-10 weeks after treatment. Reproductive performance studies demonstrated significant implantation failure in the treated uterine horns compared with controls. The number of implantation sacs in the treated and untreated horns was 0.4 +/- 0.3 and 8.9 +/- 1.0, respectively (P < 0.01). CONCLUSION: We conclude that the high rate of Pp IX conversion in the endometrial glands can be exploited to treat dysfunctional uterine bleeding with PDT. In addition, this concept may also be applied to study endometrial regeneration and embryo implantation mechanisms.

Administration, Topical↗

PubMed1996

Comparison of continuous versus pulsed CO2 and Nd:YAG laser-induced pulmonary parenchymal lung injury in a rabbit model.

BACKGROUND AND OBJECTIVE: Laser techniques have recently been described for treatment of patients with emphysema and bullous lung disease. Laser exposure of the pulmonary parenchyma during these procedures is complicated by laser-induced lung injury with substantial associated morbidity. Animal investigations are needed to develop methods that reduce lung injury. We hypothesized that the depth of injury could be reduced by pulsing laser exposures, with the goal of limiting thermal effects to more superficial tissue levels. In this study, we compared acute and chronic histologic injury resulting from pulsed- versus continuous-mode CO2 and Nd:YAG laser pulmonary parenchymal exposures in rabbits. STUDY DESIGN/MATERIALS AND METHODS: A total of 40 New Zealand White (NZW) rabbits underwent thoracotomy followed by exposure with CO2 laser (n = 10 continuous vs. n = 10 pulsed at 250 Hz with duty cycle 0.15 ms) or ND:YAG laser (n = 10 continuous vs. n = 10 pulsed at 10 Hz with duty cycle 0.10 sec) to the visceral pleural surface using 1 minute of laser exposure (5 watts, defocused to 70 W/cm2 power density) to the exposed lung surface. Rabbits were sacrificed at 4 and 21 days post-injury, and lungs were examined histologically. RESULTS: CO2 and Nd:YAG laser treatment resulted in substantial pulmonary parenchymal injury. While CO2 laser-induced damage was distinct from Nd:YAG histologically, pulsed-mode laser exposures did not reduce lung injury for either laser. Acute edema occurred to depths of 1180 +/- 338 microns for continuous-mode CO2 laser exposures compared to 1,340 +/- 430 microns in pulsed mode (p = .77). For Nd:YAG laser exposure, acute edema depth was 750 +/- 748 microns continuous versus 1120 +/- 367 microns pulsed mode (p = .65). Chronic lung fibrosis depth was 450 +/- 164 microns for CO2 continuous mode compared to 575 +/- 170 microns in pulsed mode (p = .61). Lung fibrosis depth for Nd:YAG was 550 +/- 96 microns, continuous versus 484 +/- 180 microns pulsed mode (p = .76). CONCLUSION: The similarity in injury between pulsed- and continuous-mode exposures suggests that thermal relaxation times are long relative to the selected pulse frequencies in intact living rabbit lungs. Alternatively, brief high-energy pulsations may increase focal temperatures with a tendency to increase injury depth relative to the penetration of the laser light. Thus, pulsed laser modes in these settings appear to be ineffective in reducing laser-induced lung injury in clinical settings.

Animals↗

PubMed1996

Viscosity and refractive index of follicular fluid in relation to in vitro fertilization.

PURPOSE: To set the standard values of follicular fluid viscosity and refractive index, and to investigate a possible relationship between these physiological parameters and the outcome of in vitro fertilization treatment. DESIGN AND RESULTS: 128 samples of follicular fluid were collected from 40 in vitro fertilization patients. Viscosity determinations (centipoise; mean +/- SD) for shear rates of 23, 46, 115, and 230 were 2.04 +/- 0.86, 1.84 +/- 0.49, 1.48 +/- 0.27, and 1.38 +/- 0.22, respectively. The average (+/- SD) refractive index was 1.030 +/- 0.002. There was no significant difference between the values of thawed frozen fluids and fresh samples of the same specimens. The data showed no correlation between follicular fluid viscosity or refractive index and the presence of oocytes, their maturation grade or their fertilizing capacity. CONCLUSIONS: For the first time, values of the viscosity and refractive index of follicular fluid obtained during in vitro fertilization have been determined. However, these preliminary results did not reveal any relationship between the physiological parameters examined and the outcome of in vitro fertilization treatment.

Female↗

PubMed1996

Selective photosensitizer localization in the human endometrium after intrauterine application of 5-aminolevulinic acid.

OBJECTIVE: Our purpose was twofold: to determine the distribution of the endogenous photosensitizer protoporphyrin IX in the uterus and to ascertain the time interval leading to maximal endometrial fluorescence after intrauterine instillation of 5-aminolevulinic acid. STUDY DESIGN: One milliliter of a 400 mg/ml 5-aminolevulinic acid-Hyskon solution was instilled into the uterine cavity of 27 women before hysterectomy. On frozen sections of uterine samples 5-aminolevulinic acid-induced fluorescence was measured with fluorescence microscopy. RESULTS: 5-Aminolevulinic acid-induced fluorescence could first be detected in the superficial endometrial glands 75 minutes after drug injection. In the endometrial gland stumps fluorescence intensity peaked 4 to 8 hours after 5-aminolevulinic acid instillation and was > 48 times higher than in the underlying myometrium. CONCLUSIONS: Fluorescence in the endometrial glands suggests that selective photodynamic destruction of the endometrium may be possible 4 to 8 hours after intrauterine 5-aminolevulinic acid instillation.

Aminolevulinic Acid↗

PubMed1996

Structural and functional effects of endometrial photodynamic therapy in a rat model.

OBJECTIVE: Our purpose was to determine the optical dose required for irreversible endometrial destruction and prevention of implantation by photodynamic therapy with topical 5-aminolevulinic acid. STUDY DESIGN: Three hours after drug application 74 female Sprague-Dawley rats received varying doses of 630 nm of light delivered by an intrauterine cylindric diffusing fiber. RESULTS: A 64 J/cm2 in situ optical dose resulted in long-term irreversible endometrial destruction; 43 J/cm2 damaged endometrial stroma and myometrium but not glandular epithelium 1 day after photodynamic therapy. At this lower light dose endometrium regenerated to full thickness within 3 weeks; however, implantation sacs were significantly reduced. CONCLUSIONS: Photodynamic destruction of glandular epithelium accompanies irreversible endometrial ablation, whereas isolated stromal damage leads to reproductive impairment only. The optical dose required for endometrial ablation is approximately 1.5-fold higher than for reproductive impairment (functional damage) because of differential cell photosensitivity.

Aminolevulinic Acid↗

PubMed1996

Selective photosensitizer distribution in vulvar condyloma acuminatum after topical application of 5-aminolevulinic acid.

OBJECTIVE: Our purpose was to determine the feasibility of selective photosensitization of vulvar condylomas by use of tropical application of 5-aminolevulinic acid. STUDY DESIGN: In vivo fluorescence was assessed and biopsy specimens of condylomas were taken for fluorescence microscopy in 24 patients at different times after application of 2.5% 5-aminolevulinic acid ointment or 20% 5-aminolevulinic acid cream. RESULTS: Both in vivo fluorescence imaging and fluorescence microscopy showed selective fluorescence of condylomas of the labia minora and vestibule only within short time intervals, because fluorescence of poorly keratinized normal epithelium was induced by both 5-aminolevulinic acid formulations. In non-hair-bearing skin, lesional fluorescence remained highly selective. Fluorescence microscopy showed that 90 minutes after drug application peak selectivity in epithelial lesional fluorescence was significantly higher with 2.5% 5-aminolevulinic acid ointment (4.5 +/- 0.9) than it was with 20% cream (2.1 +/- 0.2). CONCLUSION: Selective fluorescence of vulvar condyloma acuminatum can be induced by nonselective topical 5-aminolevulinic acid application. Studies evaluating selective photodynamic destruction of condylomas are justified.

Administration, Topical↗

PubMed1996

[Benzoporphyrin derivative mono acid for photodynamic therapy of the endometrium].

The aim was to study the impact of photodynamic therapy (PDT) on the endometrium after local intrauterine application of photosensitiser (Ps) and laser light without sensitising the skin. To our knowledge Benzoporphyrin Derivative Mono Acid (BPD) was used for the first time for this purpose in the rat model. The advantage of using BPD is the fact that light of 690 nm (maximum absorption) penetrates deeper into tissue and shows less absorption by haemoglobin. Low-light level tissue fluorescence imaging revealed a distinct positive endometrium-to-myometrium ratio within the first 12 hours. Relative fluorescence was highest in the endometrial glands and lowest in the myometrium. After 12 hours the intensity of fluorescence levelled off in all compartments and values of the glands approached close to those of the other layers. REPRODUCTIVE PERFORMANCE AFTER PDT: There was a significant difference in nidations (p < 0.03) in the treated left uterine horn as compared to the untreated right horn and the control animals (light/no drug and drug/no light). HISTOLOGICAL CHANGES: Following PDT a marked atrophy of the endometrial layer was observed in most animals leaving just a single cell epithelial layer covering the myometrium. SKIN PHOTOSENSITIVITY: None of the animals showed any alterations in the light treated skin area at any time. These promising results show that PDT of the endometrium is possible after topical application of the photosensitising drug and the laser light without provoking skin sensitivity.

Animals↗

PubMed1996

A mathematical model for light dosimetry in photodynamic destruction of human endometrium.

We are involved in the development of photodynamic therapy (PDT) as a minimally invasive method for treating dysfunctional uterine bleeding, one of the primary clinical indications for hysterectomy. In this paper, we analyse light propagation through the uterus in order to specify the requirements for a light delivery system capable of effectively performing endometrial PDT. Our approach involves developing an analytical model based on diffusion theory to predict optical fluence rate distributions when cylindrical and spherical optical applicators are placed in the uterine cavity. We apply the results of our model calculations to estimate the thermal effects of optical irradiation and the effective photodynamic optical dose. Theoretical fluence rate calculations are compared to fluence rate measurements made in fresh, surgically removed human uteri. Our results show that a trifurcated cylindrical optical applicator inserted into the human uterus can provide a light dose that is sufficient to cause photodynamic destruction of the entire endometrium. When the optical power per unit length of each cylindrical applicator is 100 mW cm-1 (at 630 nm), a fluence rate of 40 mW cm-2 is delivered to the boundary layer between the endometrium and the myometrium (a depth of about 4-6 mm). The optical fluence delivered to the boundary layer after 20 min of exposure is 50 J cm-2, a level that is generally accepted to cause tissue damage throughout the endometrium in most patients.

Dose-Response Relationship, Radiation↗

PubMed1996

Doppler grid surface scanning applications for pulmonary subsurface parenchymal perfusion assessment.

Subsurface perfusion to lung parenchyma underlying the pleura is difficult to assess in live ventilated animals. The purpose of this study was to assess applicability of a newly developed laser Doppler grid scanning imaging technology that measures perfusion of pleural subsurface lung regions in intact normal and abnormal animal lungs. Eighty-six Doppler grid perfusion measurements were performed in five New Zealand White Rabbits (3-5 kg); four with unilateral bullous lung disease, one normal control. Left upper lobe lung surface was exposed to 10 1-sec spot Nd:YAG exposures (70 W/cm2). One week following laser exposure, all rabbits underwent sequential bilateral open thoracotomy. Unaffected left lower lobes in these animals and all four lobes of a previously untreated rabbit were used as controls. Pleural subsurface perfusion measurements were recorded over a contiguous 900-pixel square surface grid using quantitative noncontact laser Doppler imaging during open thoracotomy procedures. Scans were obtained in a normal volume ventilation mode, at 30 cm of inspiratory hold airway pressure, and postinflation. A perfusion-pressure response curve was obtained in normal lung at 10-, 20-, and 30-cm static airway pressure. Post mortem measurements were used as 0 flow controls. Normal lung tissue was found to have relatively high pleural subsurface perfusion (1362 +/- 328 corrected units on a scale of 0-4095). Areas of atelectasis had decreased perfusion (659 +/- 512 U., 48.4 +/- 12.5% compared to normal lung, p < 0.02), but returned to normal levels after inflation of the lung (1253 +/- 363 U., p = 0.21 compared to normal). Pleural subsurface perfusion decreased uniformly and progressively as lung inflation pressure increased (p < 0.0001). Perfusion increased immediately to supranormal values following release of high inspiratory inflation pressure holds (1603 +/- 626 U., 117 +/- 18% compared to normal lung, p = 0.03). Bullae had markedly decreased perfusion (541 +/- 68 U.) that was not further reduced by increased inflation pressures. Noncontact laser Doppler grid perfusion imaging appears to provide a new tool for measuring pleural subsurface perfusion over a large area of lung surface in clinical experimental settings. Results are rapid, reproducible, and consistent. Sampling errors inherent in current point sampling Doppler flow techniques are reduced by the multiple contiguous measurements. We have used this technique to demonstrate inspiratory pressure-related reduction in pleural subsurface perfusion in normal lung, reversible decreased perfusion in atelectatic regions, and reduced perfusion in bullous and laser-treated lung regions.

Analysis of Variance↗

PubMed1996

Effects of ultraviolet exposure and near infrared laser tweezers on human spermatozoa.

Photostress has to be considered during optical micromanipulation of gametes. Ultraviolet light, including low-energy UVA (32-400 nm) radiation, as well as high-intensity near infrared (NIR) laser radiation may induce cell damage. A total number of 580 light-exposed sperm cells were studied in single-cell photostress experiments. Low-power (1.5 mW, 5.3 W/cm2) UVA exposure with 365 nm radiation of a standard mercury microscopy lamp to human spermatozoa resulted within 109 +/- 30 s in paralysis and within 310 +/- 110 s in cell death. Cytotoxic effects during cell manipulation with laser microbeams were found to be partly based on non-linear excitation phenomena, in particular two-photon absorption by endogenous cell chromophores. Two-photon absorption will be more intense in the case of pulsed laser microradiation, but occur also during micromanipulation with highly focused continuous wave (cw) microbeams used as laser tweezers ('optical traps'). In particular, short-wavelength NIR traps < 800 nm induce UVA-like biological effects (oxidative stress). For example, sperm trapping with 760 nm microbeams resulted in UVA-like autofluorescence modifications, paralysis within 35 +/- 20 s and cell death within 65 +/- 20 s. In contrast, laser microbeams at 800-1064 nm may act as relatively safe micromanipulation tools. In most optical traps multifrequency cw lasers are employed. Radiation of these lasers can magnify cytotoxic effects. Therefore, single-frequency laser operation should be preferred. In general, laser assisted cell micromanipulation requires a new understanding of microbeam-cell interaction, including aspects of non-linear optics.

Cell Survival↗