ABSTRACT
We studied the effects of angiotensin II receptor blockade with losartan on thirst and sodium appetite in pregnant Wistar rats and on their adult female offspring. During maternal adaptation to pregnancy, average daily total water intake increased by 63% (P<0.01); NaCl intake by 214% (P<0.001). These changes were not blocked by daily s.c. injections of losartan (50 mg/kg bw i.p.) from gestation day (GD) 2 until GD 19 which implied that maternal AT(1) receptors were not involved in the up regulation of thirst and sodium appetite during pregnancy. Losartan blockade during gestation led to a significant and continued increase in thirst and sodium appetite in the adult female offspring. Daily water intakes were greater in the losartan (LO) group than in the vehicle-injected control group (CO), leading to a total water intake of 1114 +/- 80.6 ml/kg bw compared with 738 +/- 56.7 ml/kg bw (P<0.05) during the 8-day period of observation. Daily sodium intakes were usually 2-3 times greater in the LO group compared with the CO group, amounting to a final cumulative intake of 232 +/- 33 mmol/kg bw compared with 93.8 +/- 16.5 mmol/kg bw (P<0.05) in 8 days. These elevated sodium and water intakes were nearly counterbalanced by the increased renal excretion of water and sodium by fully functional kidneys that were not injured by the drug. Body weights were 10% lower in the LO group at the start but remained unchanged relative to the CO group during the entire 8-day period of observation. Plasma electrolytes, blood hematocrit and carotid MABP in the LO group did not differ from the CO group.
Subject(s)
Aging/physiology , Angiotensin Receptor Antagonists , Appetite/drug effects , Losartan/pharmacology , Prenatal Exposure Delayed Effects , Sodium/administration & dosage , Thirst/drug effects , Animals , Blood Pressure/drug effects , Body Weight/drug effects , Carotid Arteries/physiology , Drinking/drug effects , Eating/drug effects , Electrolytes/blood , Female , Kidney/drug effects , Kidney/physiology , Losartan/administration & dosage , Male , Pregnancy , Rats , Rats, Wistar , Receptor, Angiotensin, Type 1 , Receptors, Angiotensin/metabolism , Sodium/urine , Time FactorsABSTRACT
BACKGROUND AND OBJECTIVE: Despite laser applications targetted toward tonsillar tissue, there has been no characterization of underlying optical and thermal events during laser irradiation of tonsillar tissue. STUDY DESIGN/MATERIALS AND METHODS: The optical properties of canine and human tonsils were determined at 805 nm (diode laser) and 1,064 nm (Nd:YAG laser). An optical-thermal simulation was developed to predict the temperature rise in irradiated human tonsils. RESULTS: The optical properties of human and canine tonsillar tissue are similar at both wavelengths. The optical-thermal simulation was validated and predicts that at 10 W and 1 minute of irradiation, the heat will be contained within the human tonsil. The diode laser causes more superficial heating than the Nd:YAG laser. CONCLUSIONS: The safety of irradiating human tonsils was shown. The diode laser is superior to the Nd:YAG laser because less heat affects collateral structures. The optical-thermal simulation detailed in this study can be used to predict the temperature rise in tissues undergoing irradiation.
Subject(s)
Lasers , Palatine Tonsil/radiation effects , Animals , Dogs , Hot Temperature , Humans , Optics and Photonics , SafetyABSTRACT
BACKGROUND AND OBJECTIVE: Mucosa intact laser tonsillar ablation is an alternative to conventional tonsillectomy. The efficacy of this procedure was demonstrated in canines, but establishing the safety of irradiating human tonsils is paramount. STUDY DESIGN/MATERIALS AND METHODS: An optical-thermal simulation of tonsillar tissue irradiation was previously developed, but the effect of varying parameters was not investigated. The tissue response to irradiation at 5-25 watts for 1 minute and 10 watts for 10 seconds to 162 seconds is simulated. RESULTS: At 15 watts and greater, the peak temperature is over 100 degrees C and the mucosal temperature is over 70 degrees C. At the depth of the tonsil, the temperature does not vary significantly. The peak temperature is at 1 mm. The radial temperature profile is not significantly altered by longer irradiation times. CONCLUSIONS: The optimal dosimetry parameters for irradiation of human tonsillar tissue at 805 nm with the MILTA technique is under 15 watts for approximately 1 minute.
Subject(s)
Computer Simulation , Laser Therapy , Palatine Tonsil/radiation effects , Dose-Response Relationship, Radiation , Humans , Mouth Mucosa/radiation effects , Optics and Photonics , ThermodynamicsABSTRACT
Transscleral cyclophotocoagulation (TSCPC) is currently performed clinically as an effective treatment for end-stage glaucoma. We develop a theoretical model for the analysis of optical attenuation phenomena during TSCPC as a basis for selection of an optimal wavelength. A multilayered Monte Carlo model was developed to calculate the fluence and the rate of heat generation in each tissue layer for the wavelengths of Nd:YAG, diode, ruby, krypton yellow, and argon lasers. Of the five wavelengths under study, our theoretical results suggest that the diode laser wavelength offers the best penetration through the conjunctiva, sclera, and ciliary muscle and highest absorption within the ciliary pigment epithelium.
ABSTRACT
Corrections are given to the reported [Appl. Opt. 35, 3321 (1996)] units of the absorption and scattering coefficients mu (a) and mu (s), respectively. The corrections pertain to two figures, several tables, and the text describing results.
ABSTRACT
A number of recent studies have demonstrated the success of Nd:YAG and diode laser transscleral cyclophotocoagulation in the treatment of advanced glaucoma. Wavelength selection, however, has seldom been based on a clear understanding of the optical properties of tissues involved. The optical properties of conjunctiva, sclera, and the ciliary body adjacent to the limbus were investigated to find an optimal wavelength range for transscleral cyclophotocoagulation. The absorption and scattering coefficients of these layers were determined in the 300-1200-nm wavelength range by the use of a one-dimensional inverse adding-doubling method. The measured optical properties of conjunctiva, sclera, and the ciliary body provide a basis for a comparative analysis of the laser wavelengths used clinically for transscleral cyclophotocoagulation.
