Thermal imaging of the temporal bone in CO2 laser surgery: an experimental model

The unique properties of lasers create an enormous potential for specific treatment of chronic ear disease. Despite the widespread acceptance and use of the laser, however, a complete understanding of the time- and space-dependent temperature distribution in otic capsule bone immediately after pulsed laser exposure has not been elucidated. Using a liquid nitrogen-cooled mercury-cadmium telluride infrared detector, the temperature distribution in human cadaveric otic capsule bone was determined immediately after pulsed (100 msec) carbon dioxide laser exposure (0.3 to 4.0 W; 200 microm spot diameter). The time- and space-dependent temperature increases and thermal diffusion were determined as a function of the laser power density and were found to vary linearly.     

Transcatheter liver lobar ablation: an experimental trial in an animal model

Complete embolization of tumor tissue together with surrounding liver sufficiently prevents collateral blood supply to the tumor, offering curative treatment for hepatic malignancies. The present experiment was designed to test the feasibility of hepatic lobar ablation by means of the transcatheter chemoembolization technique. Five groups of rats (n = 6) were treated with a mixture of iodized oil/ethanol in ratios of 5:1, 4:1, 3:1, 1:1, and 1:0, which was injected selectively into the right-lobe artery until saturation during open surgery. Another group (n = 6) was studied using in vivo microscopy to observe the distribution of the mixture in the liver and changes in hepatic microcirculation. Ethiodol/ethanol mixture entered the portal vein after injection into the hepatic artery creating dual, complete arterial and portal venous embolization. Lobar ablation effects were achieved in 2 weeks in the 5:1, 4:1, and 3:1 ratio groups, indicated by the lobe/liver weight measurements (p < 0.001 vs normal liver). Hepatic arterial administration of the Ethiodol/ethanol mixture creates dual hepatic arterial and portal venous embolization, achieving a lobar ablation effect.     

Change in temperature of subjacent bone during soft tissue laser ablation

In tissues that closely approximate bone, sufficient heat may be transferred to the bone during laser surgery to cause damage and/or necrosis. To date, there have been few studies examining the temperatures elicited at the bone surface as a result of laser application to the overlying soft tissues. The purpose of this investigation was to determine, under in vitro conditions, temperature changes at the bone/soft tissue interface during laser ablation with CO2 and Nd:YAG lasers used with and without (w/wo) air/water coolant. Experimental specimens consisted of 5 mandibles from freshly sacrificed hogs; laser treatment sites were the buccal and lingual attached gingiva of the molars and the lingual keratinized mucosa of the incisor region. CO2 and Nd:YAG lasers were used w/wo coolant at power settings of 4 to 8 W and 5 to 9 W, respectively. Temperature changes were measured with a copper constant thermocouple contained within a 21 gauge hypodermic needle. In comparing the lasers at comparable energy densities w/wo coolant, temperature increases at the bone/soft tissue interface ranged from 8.0 to 11.1 degrees C with the Nd:YAG and 1.4 to 2.1 degrees C with the CO2. Similarly, in comparing the times required for the interface to return to baseline temperature following removal of the laser, values ranged from approximately 143 to 205 and approximately 119 to 139 seconds for the Nd:YAG and CO2, respectively. Results from this study suggest that, at energy densities equal or above those reported here, the increase in temperature at the bone surface as a result of periodontal soft tissue surgery with the Nd:YAG laser could be damaging, especially if the exposure is prolonged.     

脉冲激光轰击法连续制备纳米金掺杂YBCO

利用超声法获得钇钡铜氧(YBCO)和乙醇混合溶液,采用聚焦脉冲激光轰击浸于流动无水乙醇中的金靶,连续制备得到纳米金和乙醇混合溶胶.将纳米金和乙醇混合溶胶直接滴入接收器中的YBCO和乙醇混合溶液中,经干燥获得纳米金掺杂的YBCO材料.结果发现,纳米金未明显改变YBCO的吸放热现象,对样品的组成影响不大;掺杂0.01%、0.05%重量比例的纳米金后YBCO的结晶度和超导转变温度Tc均有所提高.     

A two-year review of pain control during laser therapy using the flashlamp pulsed dye laser

Laser therapy is now accepted as the treatment of choice for port wine stains. Patient reaction to laser light exposure and methods used to control pain during 1357 treatment sessions for 350 medium to large port wine stains using the SPTL-1 laser (Candela Laser Corporation) are reported. In the majority of cases (86%) it was necessary to use either general anaesthesia or some other form of local pain control.     

Thermal side effects after use of the pulsed IR laser on meniscus and bone tissue

Stress proteins (sps) 27, 34, 70 and 90 (Mr x 10(3)) were induced in the hypothalamus of caloric restricted (CR) rats by feeding stress. A definite time pattern for sps synthesis was observed when their induction was examined at several time points after the rats were fed, and the level of sps expression was found to vary significantly at different times of the day. The same group of proteins was induced in ad libitum fed rats when they were subjected to food deprivation for 48 h. Stress protein 34 expression in the hypothalamus of old caloric restricted rats was found to be dependent on blood glucose levels, and was substantially reduced when insulin was added to the glucose infusion. The expression of sps 27, 70 and 90, however, was little changed with glucose and/or insulin infusion.     

Effects of rapid pulsed CO2 laser beam on cortical bone in vivo

Twenty rabbit femurs were used to study the effect of CO2 laser on cortical bone. Sixteen femurs were treated with 20 watts, 3 mm defocused beam, 2 KHZ spike pulse mode CO2 laser for 10 seconds through a circular window in the metaphysis. In four control femurs, the inner cortex was exposed without laser treatment. The animals were killed at 4 and 6 weeks and the specimens studied histologically. All laser-treated specimens showed thermal changes. Three histological zones were observed. A superficial zone of inner cortex close to the beam consisted mainly of carbonization or carbon ash during resorption. An intermediate zone consisted of bone necrosis and healing with associated areas of new bone formation. The deep zone of outer cortex had normal bone with no cellular damage. No such changes were observed in the control specimens. The CO2 laser can be used to generate a controlled zone of tissue ablation, which may make it a potentially useful tool for tumor margin cauterization.     

Meningiomas of the temporal bone

Meningiomas should be considered in the differential diagnosis of otologic tumors arising from the middle ear and mastoid. It is generally recognized that meningiomas may invade the temporal bone via direct extension from the intracranial space (secondary). It is not generally recognized that meningiomas can develop initially in the middle ear cleft (primary). Representative cases of primary and secondary meningiomas of the temporal bone are described and clinical aspects of diagnosis surgical management are discussed. In order to assess the pathogenesis of meningiomas of the temporal bone, histological studies were done on 200 temporal bone specimens. In certain specimens, ectopic arachnoid granulations, from which primary meningiomas may originate, were identified and described, according to location. One specimen was most unusual in that it contained ectopic glial as well as arachnoidal tissue.     

Anatomy of the temporal bone

High resolution computed tomography has proved to be invaluable in the evaluation of the temporal bone, and demonstrates its bony anatomy in exquisite detail. Furthermore, the role of magnetic resonance imaging, especially with improving high resolution techniques, has continued to expand in the past decade. A thorough understanding of normal temporal bone anatomy is a requisite for accurate radiologic evaluation. The ensuing discussion is an attempt to summarize the normal temporal bone anatomy with emphasis on clinically relevant structures, temporal bone pneumatization, and common anatomic variants.     

Various types of suprameatal spines and depressions in the human temporal bone

Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep.     

Maternal hyperphenylalaninemia: an experimental model in rats

Experimental maternal hyperphenylalaninemia produced in pregnant F344 rats by the combined use of p-Chloro-DL-phenylalanine and L-phenylalanine reduced fetal birth weight in comparison to saline-injected controls. Offspring who experiences hyperphenylalaninemia in utero died within 5 days after birth. Fetal plasma phenylalanine levels were several times higher than maternal plasma phenylalanine levels, indicating that the placenta actively concentrates maternal phenylalanine. Fetal brain phenylalanine levels rose in direct proportion to elevations in fetal plasma phenylanaline, whereas maternal brain phenylalanine levels remained low during maternal plasma phenylalanine elevation; the contrast suggests that the maternal brain is better able than the fetal brain to screen itself against high circulating plasma phenylalanine levels.     

Use of a press as support of the temporal bone in experimental otologic surgery]

Sixty-seven cases of neck exploration for suspected hyperparathyroidism were reviewed. Thirty-nine patients underwent removal of an adenoma with biopsy of one or more other parathyroid glands. In another group, nine patients underwent removal of the adenoma only. Both groups have had no recurrences of hyperparathyroidism in follow-up periods of two months to twelve years. The data presented indicate that removal of a parathyroid adenoma alone, without biopsy of other tissue, represents satisfactory treatment. Experience with hyperplastic glands is also reviewed. Subtotal parathyroidectomy was effective treatment in all patients, but a 30 per cent incidence of hypocalcemia was noted after this operation.     

Adjusting the geometry of implantable hearing aid components to human temporal bone. II: Microphone

Prerequisite to implantation of a piezoelectrical transducer of an implantable hearing aid is a shape allowing its implantation into human mastoid and middle ear. To approach this problem, a consecutive series of six transducer prototypes was created in an iterative process. Their functional geometry was evaluated in 50 human temporal bones. A shape for a functioning transducer was found which will enable implantation in 78% of the cases examined (confidence interval: 61.5%-89.2%). It will allow simultaneous implantation of the transducer into the mastoid and microphone, which is situated transmastoidal in the posterior wall of the ear canal. Furthermore, the transducer may be coupled to the ossicular chain or the perilymph.     

Glomus tumor of the temporal bone

A case story describing the typical symptoms and course of a glomus tumour of the temporal bone is presented. The most frequent symptoms are pulsatile tinnitus, unilateral hearing loss, aural fullness and paresis of the vagal nerve or other lower cranial nerves. The tumour is frequently visible by otoscopy. Despite being histologically benign, the tumour is infiltrative and may affect the surrounding cranial nerves or spread into the cranial cavity. The early signs and findings are vague. Since the sequelae are fewer when the tumour is treated while it is small, an increased awareness will be of benefit to the patients.     

Desmoplastic fibroma of the temporal bone

BACKGROUND: Desmoplastic fibroma is a benign, locally aggressive, intraosseous neoplasm with a propensity for local recurrence. Desmoplastic fibroma most commonly originates within the mandible (70% of cases), and long bones with rare lesions reported in the maxillary, frontal, and parietal bones. We report two patients with desmoplastic fibroma arising within the temporal bone. STUDY DESIGN: Case report and literature review. PATIENTS: Two patients with desmoplastic fibroma with intracranial and extra cranial growth patterns are presented. Both were young females with aural fullness and decreased hearing. INTERVENTIONS: Diagnostic and therapeutic. RESULTS: Both tumors were surgically extirpated and the patients have remained disease free for 18-48 months. Neither tumor expressed estrogen or progesterone receptors. CONCLUSION: Desmoplastic fibroma is a highly invasive local destructive lesion which is best treated by nondestructive surgical intervention. Immunohistochemical analysis may demonstrate hormonal receptors, in which case Tamoxifen may reduce recurrence.     

Right ventricular blood flow during left ventricular support in an experimental porcine model

BACKGROUND: Right ventricular blood flow may be adversely affected during left ventricular assist device (LVAD) use leading to right ventricular (RV) ischemia and RV dysfunction. This study characterized normal RV blood flow responses to LVAD operation. METHODS: Seven Yorkshire pigs weighing 74.4 +/- 3.4 kg underwent right coronary artery blood flow measurements with an ultrasonic flow probe and injection of radiolabeled microspheres. A Thoratec LVAD was used in either synchronous or asynchronous modes and RV loading was increased using a pulmonary artery snare. RESULTS: The RV blood flow was compared between three regions that differed in proximity to the right coronary artery: proximal segment, mid-RV, and distal. The right ventricular distal flow was 0.93 +/- 0.07 mL x min-1 x g-1 compared with 0.74 +/- 0.06 mL x min-1 x g-1 at right ventricular proximal flow during control measurements (p = 0.0001). This difference was maintained during LVAD operation in either synchronous or asynchronous modes and also during pulmonary artery constriction. CONCLUSIONS: Global RV flow is not adversely affected by LVAD use. A flow gradient occurs along the right coronary artery with the distal vascular bed having relatively less reserve, which may be more susceptible to ischemia in patients with preexisting coronary disease or RV distention during LVAD use.     

Treatment of photoaged neck skin with the pulsed Erbium:YAG laser

Fludarabine has been associated with an increased risk of opportunistic infections, possibly related to the induction of profound CD4+ lymphopenia. We observed two cases of cytomegalovirus pneumonia (CMV-IP) in a total of nine patients over a 5-year period who had previously received fludarabine and who proceeded to autografting. Both patients also received steroids post-transplant. CMV-IP was observed in one of 104 other autograft recipients over this time who had not received prior fludarabine. This observation suggests that the combination of fludarabine pre-transplant and steroids post-transplant may increase the risk of invasive CMV disease in autograft recipients.     

Sequential bilateral isolated lung perfusion in the rat: an experimental model

BACKGROUND: A model of isolated single-lung perfusion in the rat has been established in our laboratory to study the chemotherapeutic treatment of pulmonary metastases. A sequential bilateral isolated lung perfusion model was designed to investigate the feasibility of staged perfusions in the rat. METHODS: Twenty-four Fischer rats were randomized into three experimental groups of 8 rats each. All rats underwent left isolated lung perfusion. One, 2, or 3 weeks later, the rats in groups I, II, and III, respectively, underwent contralateral (right) perfusion. Five control animals (group IV) underwent sequential bilateral sham thoracotomies 1 week apart. Arterial blood gas analysis was performed 1 week after the second operation in the rats in groups I and IV. RESULTS: All animals survived the first operation, with 100% (8/8), 75% (6/8), and 100% (8/8) of the animals in perfusion groups I, II, and III, respectively, surviving the second operation. All control animals (group IV) survived the second sham thoracotomy. Arterial blood gas analysis did not show a significant difference in the oxygen or carbon dioxide partial pressure or the pH between group I and IV (p = 0.32, 0.96, and 0.76, respectively). CONCLUSIONS: Our experiments demonstrate that sequential bilateral isolated lung perfusion is safe in and well tolerated by the rat. This model can be used to investigate the safety and efficacy of staged perfusions with chemotherapeutic agents in the treatment of bilateral pulmonary metastases in the rat.