Combined surgery and irradiation for treatment of hypertrophic scars and keloids

This is a study of 11 patients who received combined surgery and irradiation for intractable hypertrophic scars and keloids. All of the patients received early post-operative (within 24 hours) irradiation with a 6-MeV electron beam and a total dose ranging from 1500-2100 rads in five to nine fractions after surgical excision of the lesions. The subjects were followed-up for over six months and the results are as follows: seven had a good response; three had a partial response; and one experienced a recurrence. The overall response rate was 90%, and no radiation injuries to the skin or delayed healing of the wound were noted. These preliminary outcomes are encouraging, especially for those patients who can not tolerate or have not responded well to other treatment programs.

Ventilatory dysfunction precedes pulmonary vascular changes in monocrotaline-treated rats

Rats with established monocrotaline (MCT)-induced pulmonary hypertension also exhibit a profound increase in lung resistance (RL) and a decrease in lung compliance. Because airway/lung dysfunction could precede and influence the evolution of MCT-induced pulmonary vascular disease, it is important to establish the temporal relationship between development of pulmonary hypertension and altered ventilatory function in MCT-treated rats. To resolve this issue, we segregated 47 young Sprague-Dawley rats into four groups: control (n = 13), MCT1 (n = 9), MCT2 (n = 11), and MCT3 (n = 14). Each MCT rat received a single subcutaneous injection of MCT (60 mg/kg) 1 MCT1), 2 (MCT2), or 3 (MCT3) wk before the functional study. At 1 wk after MCT, significant increases in RL and alveolar wall thickness were observed, as was a significant decrease in carbon monoxide diffusing capacity (DLCO). Medial thickness of pulmonary arteries (50-100 microns OD) and right ventricular hypertrophy were not observed until 2 and 3 wk post-MCT, respectively. Coincident with the right ventricular hypertrophy at 3 wk post-MCT were decreased DLCO and increased alveolar wall thickness and lung dry weight. Pressure-volume curves of air-filled and saline-filled lungs showed marked rightward shifts during the 1st and 2nd wk after MCT administration and then decreased at the 3rd wk. These data suggest that MCT-induced alterations in airway/lung function preceded those of pulmonary vasculature and, therefore, implicate airway/lung dysfunctions as potentially contributing to the later development of pulmonary vascular abnormalities.

Role of the axon reflex in capsaicin-induced bronchoconstriction in guinea pigs

To study the axon reflex as a contributing factor to capsaicin-induced bronchoconstriction in vivo, 30 guinea pigs weighing 325 +/- 7 g were randomly divided into four groups: Group 1, control (n = 6); Group 2, bupivacaine (n = 11); Group 3, tetrodotoxin (TTX, n = 10); and Group 4, tachykinin depletion (n = 3). Each animal was anesthetized with pentobarbital sodium, cannulated with a tracheal cannula and venous catheter, paralyzed with gallamine triethiodide, and artificially ventilated. All animals were treated with atropine and phenoxybenzamine, and a ganglionic blocking agent (chlorisondamine) was given to about half of the animals. Capsaicin (16 micrograms/kg) was intravenously injected to induce bronchoconstriction. Immediately upon the capsaicin being induced each animal exhibited a decrease in vital capacity, maximal expiratory flow and respiratory compliance, as well as a more than six-fold increase in residual volume, indicating severe bronchoconstriction. Then, the airway spasm decreased gradually toward the baseline values. The animals in Group 4 indicated a complete abolishment of the capsaicin-induced bronchoconstriction, whereas Group 2 and Group 3 displayed a significantly attenuated constriction at 15 to 20 min after capsaicin injection. Administration of chlorisondamine did not alter the capsaicin-induced bronchospasm. Since it is known that bupivacaine and TTX block nerve conduction, the data suggest that the axon reflex plays a significant role in the late phase of bronchoconstriction, which is apparently mediated via tachykinins.

Radiotherapy for postoperative recurrent uterine cervical carcinoma

From January 1980 to December 1985, a total of 110 patients with postoperative recurrent uterine cervical carcinoma were treated with radiotherapy. The mean age was 53 years. Ten patients were excluded due to incomplete treatment. The population was grouped according to the classification by Ciatto et al. into patients with central recurrence (n = 48), with peripheral limited recurrence (n = 43), and with peripheral massive recurrence (n = 9). The midpelvic dose given to patients with central recurrence was 40 to 45 Gy, followed by a boost given either by perineal teletherapy with 30 Gy or brachytherapy with 30 Gy at 0.5 cm. beneath the vaginal mucosa. For the peripheral group, the midpelvic dose was 50 Gy followed by a boost of 10 Gy through reduced portals. Further boost to the vaginal mucosa was given by either of the two methods mentioned above. The overall 5-year survival rate was 28%. In the group with central recurrence, it was 42% and in the group with peripheral recurrence 15%. Sixteen patients had persistent local tumor and 15 patients developed distant metastasis. Complications noted were proctitis (5%), cystitis (2%), vesicovaginal fistula (2%) and rectovaginal fistula (2%). Our data clearly indicate that radiotherapy was effective in controlling central recurrence, but for peripheral recurrence, control rate and prognosis were less favorable.

Inhibition of porcine pancreatic elastase-induced emphysema by eglin-c

Eglin-c, a compound that inhibits rat elastase but has little effect on porcine pancreatic elastase (PPE), was employed to examine the role of endogenous elastase in PPE-induced emphysema. Twenty-four female Long-Evans rats were divided into three groups: control (n = 8), PPE (n = 9), and PPE + eglin-c (n = 7). Eglin-c (9 mg/rat) was intratracheally instilled 3 days after PPE treatment, twice weekly, until 3 days before pulmonary function testing. Function tests and lung fixation for morphometric analysis were carried out 15-34 days after PPE treatment. Intratracheal instillation of PPE (400 IU/kg) produced significant increases in functional residual capacity, dynamic and quasi-static compliances, total lung capacity (TLC), and mean linear intercept (MLI), as well as a significant decrease in carbon monoxide diffusion coefficient. However, no significant alterations in quasi-static compliance, TLC, or MLI were found in animals treated with PPE and eglin-c. Three additional groups were used to examine the effects of intratracheal instillation of saline or eglin-c: control (n = 9), saline (n = 8), and eglin-c (n = 10). No significant change in any respiratory parameter was found in either the saline or the eglin-c group, indicating no detectable alteration in pulmonary function caused by either the intratracheal procedure or eglin-c. These data suggest that endogenous elastase is an important contributing factor in the development of PPE-induced emphysema in the rat.

Oxygen radicals in capsaicin-induced bronchoconstriction

The role of oxygen radicals in capsaicin-induced bronchoconstriction was investigated using scavengers of the radicals. A total of 48 guinea pigs weighing 293 +/- 7 g were employed in this study, which consisted of two phases. In phase 1, 35 anesthetized paralyzed animals were divided into five groups: group 1A, control (n = 6); group 1B, chronic dimethylthiourea (DMTU, n = 12); group 1C, acute DMTU (n = 6); group 1D, superoxide dismutase (n = 4); and group 1E, catalase (n = 7). All animals were injected with capsaicin (16 micrograms/kg iv), and changes in respiratory compliance and maximal expiratory flow rate were used as indicators of bronchoconstriction. The capsaicin injection caused a marked airway spasm that was significantly ameliorated by chronic DMTU pretreatment, but no amelioration was noted with the other treatments. An additional study for group 1C was performed using a double dose of DMTU. Again no amelioration was found. In phase 2, 13 animals were divided into two groups: group 2A, substance P (SP, n = 7) and group 2B, chronic DMTU + SP (n = 6). There was no significant difference in SP-induced bronchoconstriction between animals in these two groups. These data suggest that capsaicin-induced airway constriction is modulated by oxygen radicals which may augment mainly on the biosynthesis and/or axonal transport of tachykinins.

Cigarette smoke stimulates cathepsin B activity in alveolar macrophages of rats

Cathepsin B activity was determined in alveolar macrophages and cell-free bronchoalveolar lavage fluid from Sprague-Dawley rats exposed only through the nose to fresh mainstream smoke from University of Kentucky high-tar, high-nicotine reference cigarettes, and in cells and fluid from room control and sham control animals. Increased levels of blood carboxyhemoglobin and pulmonary aryl hydrocarbon hydroxylase activity in smoke-exposed animals indicated effective exposure of animals to cigarette smoke. Cathepsin B activity was quantitated with alpha-N-benzyloxycarbonyl-leucine-leucine-arginine-2-naphthylamide as substrate. Specific activity (nanomoles of substrate cleaved per milligram of protein per hour) in alveolar macrophages was increased by 43% at both 4- and 10-week exposure points in animals exposed twice daily to 10 puffs of cigarette smoke. These data indicate that maximal stimulation of the enzyme occurs within 4 weeks of the initiation of smoke exposure. When the activity was expressed on a per-cell basis, cathepsin B activity was also increased in the smoke-exposed group at both exposure points. Activity in bronchoalveolar lavage fluid of smoke-exposed animals was increased by approximately 50% at 4 and 10 weeks, but the differences were not statistically significant. These findings demonstrate that cigarette smoke is a potent inducer of cathepsin B activity in alveolar macrophages of rats.

Maximal expiratory flow in the guinea pig

Using the whole body plethysmograph, the maximal expiratory flow-volume (MEFV) curve was performed in anesthetized-paralyzed guinea pigs with intact chest (n = 7) and in anesthetized, chest-open animals following exsanguination (n = 13). The pressure-volume (PV) curve was also measured. Before and after the MEFV and PV maneuvers, lung volume was determined with a neon dilution method. Peak maximal expiratory flow (Vmax) of 178 +/- 7 ml/sec occurring at 83% TLC. After the peak flow, Vmax decreased gradually with reducing lung volume. The Vmax-static recoil pressure curve was relatively linear up to PL = 5 cmH2O. Density-dependence of Vmax (helium-Vmax was significantly higher than air-Vmax) was found at or above 60% TLC but not at lung volume below 60% TLC. For the chest-open postmortem guinea pig, Vmax and TLC decreased while trapped gas volume increased gradually with time after exsanguination, indicating that bronchoconstriction gradually became more severe. The magnitude of this postmortem airway spasm was related to age and anesthetic used.

Airway resistance measured in liquid-trapped guinea pig lungs by micropuncture

We studied the relationship between bronchoconstriction and the degree of trapping in saline-filled lungs isolated from guinea pigs postmortem after rapid exsanguination. Airway resistance was measured in nine lungs, and in five lungs the site of airway narrowing was located radiographically. Animals were anesthetized with pentobarbital sodium, degassed by O2 absorption, then rapidly exsanguinated when O2 absorption was almost complete. Liquid trapping was assessed from the pressure-volume behaviour measured in saline-filled lungs. During a slow deflation from maximum volume, alveolar liquid pressure (Palv) was measured by the micropipette-servonulling method, airway opening pressure (Pao) by a strain gauge, and flow rate (Q) by weighing a reservoir connected to the airway. Airway resistance (Raw) was calculated at different lung volumes from the relationship: Raw = (Palv-Pao)/Q. In untreated lungs, Raw and fluid trapping were relatively high, and severe bronchoconstriction occurred at the level of the main stem and lobar bronchi. Nifedipine infusion reduced Raw 40-fold and decreased trapping. Raw was further reduced 10-fold and fluid trapping was minimal in lungs pretreated with nifedipine before exsanguination. Results suggest a close association between bronchoconstriction and fluid trapping in guinea pig lungs.

The tracheal nonadrenergic noncholinergic inhibitory system during antigen challenge

This study was undertaken to test the hypothesis that malfunction of the nonadrenergic noncholinergic inhibitory system (NANCIS) induces hyperreactive airways. Antigen sensitized guinea pigs were divided into four groups: (1) antigen challenge (n = 6), (2) 2 min oxyhemoglobin (HbO2) + antigen challenge (n = 5), (3) 27 min HbO2 + antigen challenge (n = 4), and (4) 2 min HbO2 + transmural stimulation (TS) + antigen challenge (n = 6). These animals were sensitized with ovalbumin 10 days before the study. In addition, 12 normal control animals without antigen sensitization were used for comparison. Under artificial ventilation, the anesthetized-paralyzed animals were hourly injected with atropine (0.2 mg/kg) and propranolol (1 mg/kg). Cervical segment of the trachea was converted to a closed tracheal pouch filled with Krebs solution containing also atropine (1 microM) and propranolol (3.5 microM). A change in the pouch pressure (Pp) reflected NANCIS TS- or antigen (5 micrograms) challenge-induced relaxation and/or constriction. HbO2 was used to inhibit NANCIS transmitter. There was no significant difference between normal and sensitized animals in the NANCIS TS-induced relaxation. Antigen challenge resulted in biphasic alteration in Pp, an initial increase and then a decrease after about 7 min. HbO2 pretreatment alone did not potentiate antigen-induced increase in Pp. HbO2 + TS, however, significantly abolished the late relaxation phase after antigen challenge.

Augmentation of elastase-induced emphysema by cigarette smoke. Effects of reduced nicotine content

To examine the role of nicotine in the augmentation of elastase-induced emphysema by cigarette smoke, animals that had been pretreated with porcine pancreatic elastase (PPE) were exposed to cigarette smokes that had a five-fold difference in their nicotine concentrations. Young adult female Long-Evans rats were divided into seven groups: (1) untreated controls; (2) low nicotine cigarette smoke exposure (Kentucky 2A1 reference cigarettes; 35.0 mg total particulate matter, 0.42 mg nicotine, and 0.38 mg nitrogen oxides per cigarette); (3) high nicotine cigarette smoke exposure (Kentucky 2R1 reference cigarettes; 38.8 mg total particulate matter, 2.2 mg nicotine, and 0.34 mg nitrogen oxides per cigarette; (4) PPE alone; (5) PPE + sham smoke exposure; (6) PPE + 2A1 smoke exposure; and (7) PPE + 2R1 smoke exposure. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 10 puffs of cigarette smoke daily, 7 days/wk for 14 wk. Sham-treated animals received room air in place of cigarette smoke. After the exposures, pulmonary function tests were performed under general anesthesia. Whole lungs were examined for gross pathologic changes, and samples of lung tissue were harvested for quantitative morphometry. Cigarette smoke exposure alone did not produce significant changes in pulmonary function or structure. On the other hand, treatment with elastase alone produced a constellation of pulmonary functional and structural changes that were pathognomonic of emphysema. Exposure to 2R1 but not 2A1 cigarette smoke significantly augmented the emphysematous changes produced by PPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic GMP affecting the tracheal nonadrenergic noncholinergic inhibitory system

An association between guanosine 3',5'-monophosphate (cyclic GMP) and the nonadrenergic noncholinergic inhibitory system (NANCIS) has been demonstrated in the isolated bovine tissue (Bowman and Drummond, 1984). In order to investigate this association in the guinea pig trachea, we used cyclic GMP derivatives, guanylate cyclase activators (N-methylhydroxylamine (NMH) and nitroglycerin (NG)] and inhibitors [oxyhemoglobin (HbO2) and methylene blue (MB)]. Under general anesthesia paralysis, the animals were ventilated and hourly injected with atropine (0.2 mg/kg) and propranolol (1 mg/kg). Cervical segment of the trachea was converted to a closed tracheal pouch and then filled with Kreb's solution augmented with atropine (1 microM) and propranolol (3.5 microM). A decrease in the pouch pressure (Pp) reflected NANCIS nerve transmural stimulation (TS)--or drug-induced relaxation. Pharmacological agents were applied intravenously. At 2-11 min after injection, NMH and NG decreased baseline Pp and reduced TS-induced relaxation. NMH, which is more potent than NG in activating particulate guanylate cyclase activity, potentiated the TS-induced relaxation at high frequencies, but NG did not. HBO2 inhibited the TS-induced relaxation at high but not at low frequencies. In contrast, MB inhibited the relaxation at low but not high frequencies. The results suggest that activation of particulate or membrane bound guanylate cyclase potentiates NANCIS-induced decrease in Pp. Therefore, there is a possible association between cyclic GMP and the NANCIS in the guinea pig trachea.

Fluid trapping in postmortem guinea pig lungs

To examine severe bronchoconstriction obstructing airways in the fluid-filled postmortem guinea pig lung, lungs were infused and deflated with isotonic solution following exsanguination. Guinea pigs were classified into 2 groups: young and mature, and each group was further classified into 2 subgroups: those receiving saline (Ca2+-free) and Tyrode's (Ca2+-containing) solutions. Each subgroup consisted of 7-8 animals. No significant change in total lung capacity from the baseline (prior to exsanguination) air value was observed in any subgroup within the experimental period of 60 min. However, both deflation volume (DV) and inflation volume (IV) decreased gradually with time; these decreases were larger in the saline-filled lungs than those of lungs infused with Tyrode's solution at 20-30 min. In the Tyrode's solution-filled lungs, larger decreases in DV and IV were found in the mature animals than in the young animals at 15-20 min. Trapped fluid volume (VT) increased gradually with time and reached mean values ranging from 9.1 to 11.5 times the baseline value at 60 min. No significant difference in VT between subgroups was observed. At any given time in all animals, the increase in VT was always equal to or larger than the decrease in DV or IV. Fluid cuffing around vessels and airways was demonstrated in the saline, but not in the air-filled lung. The data suggest that severe bronchoconstriction obstructing airways did not occur in postmortem fluid-filled guinea pig lungs. Dilution of mediators may be responsible for eliminating postmortem severe airway spasm and swelling of interstitium may induce the temporal increase in trapped volume in the fluid-filled lung.

Calcium dependency of massive postmortem bronchoconstriction in guinea pig lungs

Calcium antagonists were employed to examine whether or not guinea pig's postmortem bronchoconstriction is calcium dependent. First, a group of 17 young (3-4-week-old) animals were divided in three subgroups: control, nifedipine, and 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8, an intracellular calcium antagonist). A second group of 12 mature (5-7-week-old) animals were divided into two subgroups: control and nifedipine. Baseline pressure-volume (P-V) curves were performed prior to cannulation of the pulmonary artery in the anesthetized, opened chested animal. The lungs of the animal were then perfused and P-V curves were obtained again at intervals for up to 60 min. Nifedipine (10(-6) M) or TMB-8 (5 X 10(-4) M) was added to the perfusate in experimental groups. A temporal decrease in inflation volume (IV, the lung volume between transpulmonary pressure of 0 and 30 cm H2O during inflation) was used as an indicator of bronchoconstriction. In control subgroups, the decrease in IV was significantly greater (P less than 0.05) in the young (29.5 +/- 12.9% baseline at 20 min) than in the mature animals (75.0 +/- 7.0% baseline at 20 min). Nifedipine significantly alleviated (P less than 0.05) the decrease in IV in young animals at 15-30 min (58.6 +/- 8.4% baseline at 20 min) while TMB-8 (90.6 +/- 2.1% baseline at 20 min) prevented the decrease even further. Nifedipine did not have a significant effect on IV in mature animals. These data suggest that the postmortem bronchospasm is much more severe in young animals and that this severe constriction is calcium dependent.

Substance P-inducing massive postmortem bronchoconstriction in guinea pig lungs

To further examine the role that substance P plays in initiating the observed massive postmortem bronchoconstriction in guinea pig lungs and to explore the role of neural reflex in this airway spasm, six groups of animals were employed: control (n = 6), morphine (n = 6), substance P (n = 5), chronic capsaicin pretreatment + substance P (n = 5), tetrodotoxin (TTX) + acute capsaicin (n = 4), and chlorisondamine + acute capsaicin (n = 5). Pressure-volume curves were performed prior to and following the initiation of artificial pulmonary perfusion with 1% bovine serum albumin and 5% dextran in Tyrode's solution. A decrease in inflation volume (the lung volume between transpulmonary pressure of 0 and 30 cmH2O during inflation) was used as an index of bronchoconstriction. In control animals, inflation volume decreased to 20-30% of the base-line value at 15-30 min of perfusion, indicating massive bronchial constriction during this time period. Morphine (an agent inhibiting substance P release) significantly attenuated the spasm, whereas the presence of substance P in the perfusate markedly enhanced the constriction. Depletion of endogenous substance P by chronic capsaicin pretreatment did not affect exogenous substance P-induced spasm. Acute capsaicin-induced bronchoconstriction was significantly attenuated by TTX but was not affected by the ganglionic blocking agent, chlorisondamine. These data suggest that substance P initiates the massive postmortem bronchoconstriction in guinea pig lungs and that substance P is released by local stimulation of sensory nerve endings via axonal reflex.

Augmentation of elastase-induced emphysema by cigarette smoke: effects of reducing tar and nicotine content

The effects of reducing the tar and nicotine concentration of cigarette smoke were examined in a rat model of smoke-augmented, porcine pancreatic elastase- (PPE-) induced, pulmonary emphysema. Sixty-eight female Long-Evans rats were divided approximately evenly into seven groups: control, PPE, PPE plus sham smoke, high-tar/nicotine cigarette smoke (2R1; 38.8 mg total particulate matter and 2.2 mg nicotine per cigarette), low-tar/nicotine cigarette smoke (1R4F; 10.8 mg total particulate matter and 0.8 mg nicotine per cigarette), PPE + 2R1, and PPE + 1R4F. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 8-10 puffs of cigarette smoke daily, 7 d/wk for 12 wk. Sham-treated animals received room air in place of cigarette smoke. At the conclusion of the exposures, pulmonary function tests were performed under general anesthesia. Cigarette-smoke exposure alone did not produce significant changes in pulmonary function. Elastase-treated groups demonstrated significant increases in total lung capacity, functional residual capacity, and dynamic and static compliance, as well as significant decreases in carbon monoxide (CO) diffusing capacity and CO diffusion coefficient. Morphometric measurements of mean linear intercept demonstrated a loss of alveolar fine structure with enlargement of distal airspaces in PPE-treated rats. Exposure to either 2R1 or 1R4F cigarette smoke significantly enhanced many of the emphysematous changes produced by PPE, but there were no significant differences between the effects of the two smokes. These data indicate that reducing the tar and nicotine concentration of cigarette smoke does not lessen its ability to augment PPE-induced pulmonary emphysema in the rat.

Distribution of ascorbate in the retina, subretinal fluid and pigment epithelium

The posterior segment of the eye was divided into four compartments: retinal cytosol (R), subretinal fluid on the retinal surface (S/R), retinal pigment epithelial (RPE) cytosol, and subretinal fluid on the RPE surface (S/RPE). The volume of each compartment was estimated from the dilution of creatinine (in the extraction buffer) by the endogenous tissue fluid. The ascorbate concentrations in R, S/R, S/RPE, and RPE were 20.6, 12.3, 3.7, and 5.8 mg/dl respectively. Dehydroascorbate was observed only in the RPE and S/RPE. The decreasing ascorbate concentration from the retina to RPE, and the distribution of dehydroascorbate suggest a movement of ascorbate from the vitreous cavity into the subretinal space. The permeability of retinal cell layers to ascorbate was confirmed by the high radioactivity observed in the subretinal space after an intravitreal injection of C14-ascorbate. The occurrence of dehydroascorbate in the RPE and the S/RPE indicates the presence of oxidative reaction of ascorbate in these compartments, where light induced free radicals are located.

Comparison of five methods of analyzing respiratory pressure-volume curves

Five methods of analyzing the deflation limb of respiratory pressure-volume (PV) curves obtained from seven groups of rats that had undergone various treatments were compared. The five methods utilized measurements of: y intercept and slope with simple exponential curve fitting; area under the curve; volumes at fixed pressures; shape constant, k, of the sigmoid curve described by Paiva et al. (Respir. Physiol. 23:317, 1975); and quasi-static compliance. The seven groups of rats were treated as follows: control (n = 10); high tar/nicotine cigarette smoke exposure (n = 10); low tar/nicotine cigarette smoke exposure (n = 9); intratracheal elastase (n = 10); intratracheal elastase plus sham smoke exposure (n = 10); intratracheal elastase plus high tar/nicotine cigarette smoke exposure (n = 9); and intratracheal elastase plus low tar/nicotine cigarette smoke exposure (n = 10). Elastase treatment caused a leftward and upward shift of the PV curve and this shift was augmented by exposure to either high tar/nicotine or low tar/nicotine cigarette smoke. Using Duncan's multiple range test, we found that the y-intercept measurement of method 1, the area under the curve, volumes at fixed pressures, and quasi-static compliance methods were better able to differentiate PV curves between groups than were the slope measurement of method 1 and the shape constant measurement of method 4.

A study of photoreceptor-retinal pigment epithelium complex: age-related changes in monkeys

Retinas of 4-, 10-, and 20-year-old monkeys were studied by light microscopy, electron microscopy, and scanning electron microscopy. Sections from the midperipheral region of every retina were selected for comparison. Although no significant differences were found between 4- and 10-year-old retinas, four major changes were found in 20-year-old monkey retinas: (i) increased number of displaced photoreceptor cells (DPC), (ii) increased number of macrophages of different morphology in subretinal space, (iii) increase in pigment granules in retinal pigment epithelium (RPE) cells, and (iv) altered morphology of Muller cells. DPC included both rods and cones. Their location and morphology depended on the stage of their displacement. These cells were usually oval or rounded in shape and were found either among the outer segments of other photoreceptor cells, having stalks extending into the outer nuclear layer, or were located in the subretinal space and had no stalk. A narrow space around the DPC stalks, indicating a change in the intercellular connection between photoreceptor cells and Muller cells, was observed. Furthermore, the Muller cells related to DPC had shortened and markedly reduced microvilli. Two types of macrophages were found in the subretinal space of aged monkey retinas. One type was similar in morphology to RPE cells. Some of these cells were noticed detaching from RPE. Other types of macrophages were nonpigmented. The modifications in RPE were closely related to the changes in the associated neuroretina. The RPE cells in aged retina were devoid of microvilli or had a few thin microvilli. The pleomorphic pigment granules were dispersed throughout the cytoplasm. These cells varied in their size, shape, and surface features. These changes could significantly alter the retinal metabolic equilibrium and may be indicative of age related degenerative processes.

Distribution of retinoids in different compartments of the posterior segment of the rabbit eye

Using high-performance liquid chromatography, the amounts of all-trans retinol, retinal and retinyl palmitate were measured in the following ocular tissues and fluid of the light (LA) and dark adapted (DA) rabbit: cytosol and membrane fractions of the retina (R/C and R/M), cytosol and membrane fractions of the retinal pigment epithelium (RPE/C and RPE/M), subretinal fluid collected from the inter-photoreceptor matrix (S/R) and the matrix between apical microvilli of the RPE (S/RPE). The total amount of all-trans retinol extracted from LA eyes, 2.74 nmol per eye, was ten times greater than the amount extracted from DA eyes. In the LA eye, most of the all-trans retinol was extracted from the membrane fraction of the retina (67%); in the DA eye, most of the retinol was extracted from the cytosol fraction of the retina (58%). In contrast, the DA eye yielded more all-trans retinal (9.84 nmol) than the LA eye (5.80 nmol) and most of this retinoid was recovered from the cytosol and membrane fractions of the retina. A higher amount of all-trans retinyl palmitate was recovered from the LA eye (5.88 nmol) than the DA eye (2.02 nmol). Although most of this retinyl palmitate was extracted from the cytosol fraction of the RPE (45%, LA eye), appreciable amounts were found in all other ocular compartments. The amount of retinyl palmitate in the LA eye exceeded that of the DA eye in every compartment examined in the present study, suggesting a possible important role of retinyl esters in the visual cycle.

Factors affecting massive postmortem bronchoconstriction in guinea pig lungs

To examine endogenous factors affecting the development of the massive bronchoconstriction in the postmortem guinea pig lung, 58 anesthetized open-chest animals were divided into three groups: 1) exsanguination only (n = 13), 2) pulmonary perfusion with 5% dextran and 1% bovine serum albumin (BSA) in Tyrode's solution (Ca2+ perfusate) (n = 21), and 3) pulmonary perfusion with 5% dextran and 1% BSA in saline (Ca2+-free perfusate) (n = 24). These groups were further divided into several subgroups according to treatments: 1) substance P depletion by chronic administration of capsaicin, 2) acute capsaicin treatment to release substance P, 3) dazoxiben treatment to block endogenous synthesis of thromboxane A2, 4) diethylcarbamazine treatment to eliminate leukotriene (LT) synthesis, and 5) FPL 55712 treatment to antagonize actions of LT. Vital capacity from the deflation pressure-volume (PV) curve of the lung was used as the indicator of bronchoconstriction. Most PV curves were performed for 30 min following exsanguination or artificial perfusion. Ca2+-free perfusate enhanced the airway spasm at 5-10 min, but the spasm disappeared gradually after 10 min. Substance P depletion significantly decreased (P less than 0.01) the bronchial constriction at 20-30 min, whereas substance P release induced severe airway spasm (P less than 0.01) during the entire study. In addition, FPL 55712 reduced the bronchospasm (P less than 0.05) in Ca2+ perfusate at 30 min. Thus Ca2+ and several endogenous mediators may be involved with the airway spasm of the postmortem guinea pig lung.

Histamine and leukotrienes mediate pulmonary hypersensitivity to antigen in guinea pigs

To study roles of histamine and slow-reacting substance of anaphylasis (SRS-A) in mediating airway responses following antigen challenge, mediator antagonists were administered to guinea pigs sensitized with ovalbumin 10 days before the study. Twenty-three animals were divided into the following five treatment groups: 1) saline only (control 1, n = 5); 2) antigen challenged (n = 5); 3) antigen + methapyrilene (antihistamine, n = 5); 4) FPL 55712 only (SRS-A antagonist, control 2; n = 4), and 5) antigen + FPL 55712 (n = 4). Control groups were not sensitized. Experimental values were compared with those of control 1 at equal times after injections. Pulmonary resistance (RL), dynamic compliance (Cdyn), breathing frequency (f), tidal volume, minute ventilation (VE) and systemic arterial pressure were measured for 15-20 min just before (base line) and for up to 30 min after saline or antigen administration. Antigen challenge alone induced maximal respiratory changes at 5 min. RL increased 131 +/- 28% above base line (P less than 0.05), whereas Cdyn decreased slightly (28 +/- 10%, P less than 0.05). Antihistamine almost eliminated all changes in RL but did not affect decreased Cdyn. On the other hand, FPL 55712 eliminated changes in both RL and Cdyn. Both antagonists blocked the transient increase in VE, but neither blocked the rise in f at 5 min. We conclude that antigen-induced bronchoconstriction (RL) may be primarily mediated by histamine, whereas simultaneous alterations in Cdyn may depend mainly on leukotrienes and those in f depend on neither.

Massive postmortem bronchoconstriction in guinea pig lungs

A special phenomenon (difficult to inflate and deflate) occurring in the postmortem guinea pig lungs was studied in 40 animals. Thirty minutes after excision of the lungs or exsanguination, less than 50% of the lungs could be inflated even at high inflation pressure (34 cmH2O), and most gas was trapped during deflation. The amount of trapped gas volume at 30 min was related to the degree of lung inflation maintained during the 5- to 30-min period after exsanguination. Since stiffness of the lung tissue was unlikely to explain the phenomenon, we speculated airway obstruction as the major factor. No foam or bubbles were found in larger airways and we thus hypothesized that the obstruction was due to bronchoconstriction. This was confirmed histologically in that the lumina of both bronchi and bronchioles were constricted. The latent period to the onset of this constriction was short (approximately 5 min). It was not associated with O2 availability but was delayed an additional 15 min by a thromboxane inhibitor (dazoxiben). Neither maintaining lung temperature at 37 degrees C nor vagotomy and/or cervical transection prevented the constriction. Without exsanguination, onset of bronchoconstriction was delayed by about 1 h. We conclude that postmortem bronchoconstriction may be caused by release of an endogenous constrictor agent.

Sampling and analysis of cerebrospinal fluid for chronic studies in awake rats

A method is described whereby cerebrospinal fluid (CSF) may be sampled repeatedly from awake rats over a period of 1 to 10 wk. Stainless steel or Teflon catheters (22-gauge) were implanted in the cisterna magna of anesthetized rats (n = 19) via a midline hole immediately rostral to the interparietal-occipital suture. Several days later almost simultaneous CSF and blood samples from the same air-breathing animals were slowly drawn into glass capillary tubes. pH was determined immediately by electrode and total CO2 by microgasometer. Because sampling via Tygon microbore tubing attached to the implanted catheters allowed part of CSF CO2 content to be lost through the tube wall, stainless steel tube is preferred to make this connection. For mock CSF, total CO2 calculated from pH and PCO2 values was closely comparable to that directly measured by microgasometer. CSF pH, PCO2, and [HCO-3] in five awake rats were found to be similar to those reported in the literature for the briefly anesthetized rat. The sampling procedure did not of itself significantly alter breathing patterns (n = 14). Thus, chronic CSF sampling is feasible in awake rats for purposes of studies of ventilatory control.

In vitro buffer value of brain tissue during prolonged hypercapnia

Ventilatory adaptation to CO2 has been related to a return toward normal pH via an increase in CSF and arterial [HCO3(-)]. To examine whether the overall brain tissue can contribute HCO3(-) to surrounding fluids, we measured the in vitro CO2 buffer value (beta CO2) of control and hypercapnic rat brain homogenates and compared values with reported in vivo data. Hypercapnic rats were exposed to 7% CO2 for 3 days or 1 week. Brain homogenate was continuously tonometered for 3 h at 37 degrees C with 2%, 5% and 15% CO2 in O2. In addition, we used KOH to determine the brain buffering in the pH range 6.8-10.25. During CO2 titration, [HCO3(-)] increased gradually with time up to 90 min by about 10-15%, but the increase was blocked by a metabolic inhibitor, NaF, beta CO2, estimated per kg brain tissue from the dilute homogenate, ranged between 23.4 +/- 2.7 (SD) in controls and 26.0 +/- 1.3 meq/pH in the 7 day group, which were not significantly different. Over the same 7 days, CO2 dissociation curves were shifted upwards with similar slopes by about 6 ml/100 g tissue in association with a rise in pH of about 0.06, consistent with an accumulation of HCO3(-) without any change in buffers. No significant differences between groups were found from KOH titration curves, either in slope or position, consistent with lack of alteration in buffers as well. In vitro brain tissue beta CO2 (about 25) was less than reported in vivo values in the literature (around 40), possibly because H+ adjustments by whole body occur so rapidly in vivo. In addition, other investigators demonstrated that a major part of the increased brain cell [HCO3(-)] in prolonged hypercapnia could not be accounted for by the fixed acid production (Acta Physiol. Scand. 83: 344, 1971). By assuming the in vitro beta CO2 measures the available non-carbonic buffers, the data may be interpreted as showing that the overall brain tissue accumulates HCO3(-) from surrounding fluid during hypercapnia.

End-expiratory volume in the rat: effects of consciousness and body position

Functional residual capacity (FRC), tidal volume (VT), and frequency (f) were compared in 23 rats while either awake and unrestrained or anesthetized. FRC was determined from gas compression with closed airway inside a cone-shaped body plethysmograph. In the awake state (mean +/- SD), FRC was 1.02 +/- 0.22 ml/100 g, VT was 0.38 +/- 0.06 ml/100 g, and f was 142 +/- 22 breaths/min. During anesthesia, FRC decreased (P less than 0.01) to 52.9% of awake values, VT increased (P less than 0.01) to 147.4%, and f decreased (P less than 0.01) to 71.8%, leaving minute ventilation almost unchanged. An additional seven rats were used to examine postural effects on FRC during anesthesia, and in another seven animals pleural pressure changes were monitored. Dynamic lung compliance (0.80 ml . kg-1 X cmH2O-1) was not altered by anesthesia, but the pressure-volume curve was shifted 6 cmH2O higher. Thoracic compression, followed by a time-dependent effect of volume history, may account for the major change in FRC. The remainder of the decrease in FRC may be due to lower breathing frequency, loss of inspiratory muscle activity, and/or less airway resistance after anesthesia. Peak diaphragmatic electromyogram per unit VT was shown to increase almost linearly with FRC, indicating that diaphragmatic efficiency was decreased as lung volume was elevated.

Interphotoreceptor retinol-binding proteins: possible transport vehicles between compartments of the retina

In the eye, vitamin A (retinol) is mainly stored in the retinal pigment epithelium(RPE) although its primary function is in the visual process in the photoreceptor organelles of the neural retina (NR). It is well established that during light adaptation, the amount of retinol drops in the NR but rises in the RPE. During dark adaptation, the converse occurs. This indicates a migration of retinoid between the two tissues, the direction of which is dictated by the state of light or dark adaptation of the photoreceptors. The mechanism by which this migration is effected is unknown. We now present evidence that at least one protein exists in the subretinal space or on the cell surfaces which demonstrates many of the unique characteristics one would expect of an interphotoreceptor retinol-binding protein and could function as a vitamin A transport vehicle between NR and RPE.

Retinal gangliosides in RCS mutant rats

The distribution of retinal gangliosides was studied in normal and mutant rats with retinal dystrophy at 30 and 180 days of age. The loss of photoreceptor cells in the retinal dystrophic RCS rats was not associated with a significant reduction in the relative distribution of any of the major retinal gangliosides. The loss of photoreceptors, however, caused a marked increase in total retinal ganglioside concentration. These findings suggest that photoreceptor cells contain a low concentration of gangliosides and that no major retinal ganglioside is localized or concentrated in these cells. The cellular localization and function of the most abundant retinal ganglioside, GD3, is discussed.

Mechanical properties of rat lung during prolonged hypercapnia

Young adult rats were exposed to short-term (2 or 4 h) and prolonged (1 day to 3 wk) 5% CO2 to determine whether changes in lung mechanical properties might contribute to ventilatory adaptation. Anaesthetized rats were tracheotomized for measurement of functional residual capacity (FRC) and respiratory rates (chest intact), and for pressure-volume (PV) curves (chest open). Total lung capacity, minimal volume, lung compliance, and lung wet weight-to-dry weight ratio did not change significantly (P greater than 0.05) from air control values with CO2 exposure. From 4 h to 3 wk of hypercapnia, FRC was increased significantly (P less than 0.01) by about 25%; some of this rise could be associated with dynamic factors such as increased breathing frequency. Lung PV curves showed a small (0.5 cmH2O) left shift early in the short exposure period; this reversed into a slight (0.5 cmH2O) right shift after prolonged CO2. It is unlikely that these relatively small changes in FRC and lung recoil could contribute significantly to the previously reported long-term ventilatory adaptation to CO2.

Ventilation during prolonged hypercapnia in the rat

Awake rats, with chronically implanted arterial catheters and abdominal thermistors, were continuously exposed to 5 or 7% CO2 in air in an environmental chamber for up to 3 wk. To obtain measurements, rats were transferred to a body plethysmograph flushed with the same CO2 mixture, and, after stabilization, O2 consumption (Vo2), ventilation (VE), and arterial blood gases (ABG) were determined. After 2-h exposure, VE, tidal volume/inspiratory time (VT/TI), and VO2 were significantly increased. Thereafter, VE and VT/TI fell gradually with time, the largest decrease occurring within the 1st day of exposure. The increase in VO2 was maintained up to 3 days and then declined. ABG revealed extensive metabolic compensation for respiratory acidosis within 3-7 days. delta(VT/TI) correlated well with delta VE and delta [HCO3]a (P less than 0.05). It is likely that the gradual return toward normal pHa reduces ventilatory drive (VT/TI), which in turn lowers VE. Estimated alveolar ventilation did not decrease consistently with time in parallel with VE, suggesting that the early ventilatory overshoot might also be due to an increase in dead space.

Retinitis pigmentosa. Animal model: hereditary retinal degeneration in Wag/Rij rats

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Studies of the pathogenic mechanisms of light on rat retina

The effects of low-intensity light on the rat retina was investigated by light, transmission and scanning electron microscopy. The earliest signs of light damage were observed in the retinal pigment epithelium (RPE) of albino rats after 24 h of exposure to 35 footcandles of fluorescent light at room temparature (24 °C). These changes included an increase in the electron density of the cytoplasmic matrix, modifications of the endoplasmic reticulum, changes in the number and distribution of lysosomes and changes in the number and size of apical processes and their population of inclusions. Newly phagocytized outer segments were not seen in the RPE whereas large numbers of condensed lamellated inclusions had accumulated. This suggested that damaged RPE is unable to phagocytize outer segments and to digest previously phagocytized outer segments as a result of changes in the endoplasmic reticulum and the phagolysosomal system. Pigmented rats were more resistant to light damage than albino rats; when exposed to the same continuous low-intensity light of 35 footcandles for 4 weeks, pigmented rats developed remarkable alterations in the RPE without any morphological changes in the photoreceptor cells or their outer segments. The initial site of light damage was apparently in the RPE. The early extensive changes in RPE indicated the disruption of normal metabolic activities in the RPE; the subsequent alterations of the RPE-photoreceptor metabolic equilibrium is probably the initial step of photic retinal damage induced by low-intensity light.

Animal model: peripheral retinal degeneration in rats

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Lung volume and pleural pressure in the anesthetized hamster

Lung volumes and respiratory pressures were measured in anesthetized male hamsters weighing an average 117 g. In 16 supine animals functional residual capacity (FRC) determined by body plethysmograph was 1.12 +/- 0.23 (SD) ml (about 20% total lung capacity, TLC) slightly and significantly larger than the FRC measured by saline displacement, 1.01 +/- 0.15 ml. Similar results were found in six prone animals. Paralysis did not significantly alter supine FRC. Contrary to published reports, pleural pressure (Ppl) estimated from esophageal pressure was negative at FRC. The fact that lung volume decreased by 0.2 ml (about 4% TLC) when the chest was opened at FRC provided additional evidence of negative Ppl at FRC. No consistent changes in the lung pressure-volume curve were found after the chest was opened. Deflation chest wall compliance just above FRC was about twice lung compliance. The vital capacity and reserve volumes in this study agreed with values reported in the literature. However, absolute lung volumes (TLC, FRC, and residual volume) were lower by about 1.4 ml, possibly because of earlier overestimates of box FRC.

Respiratory mechanics in recumbent dogs anesthetized with thiopental sodium

Pressure-volume (PV) and conductance-volume (GV) curves were obtained in trained dogs awake and then anesthetized with thiopental sodium, in the prone left lateral decubitus, and supine positions. By paired analyses, induction of anesthesia had no significant effect on lung volumes, static PV curves of the lung or chest wall, or static compliance of the lung or chest wall. In addition, change of posture had little effect on these variables in either the awake or the anesthetized state. Frequently, however, individual dogs showed changes in lung PV curves after induction of anesthesia or change of posture. These PV curve shifts were not accompanied by predictable changes in GV relations. Therefore, we concluded that such changes in the lung PV curve reflect either local artifacts or local deformation of the respiratory system.

Respiratory mechanics in the anesthetized rat

Functional residual capacity (FRC) and pressure-volume (PV) curves of the lung, chest wall, and total respiratory system were studied in 15 anesthetized rats, weighing 307 +/- 10 (SE) g. Pleural pressure was estimated from the esophageal pressure measured with a water-filled catheter. The FRC determined by body plethysmograph was slightly and significantly larger than FRC determined from saline displacement of excised lungs. The difference may be accounted for by O2 uptake by lung tissue, escape of CO2 through the pleura, and abdominal gas. Paralysis in the prone position did not affect FRC, and abdominal gas content contributed only slightly to the FRC measured by body plethysmograph. Values of various pulmonary parameters (mean +/- SE) were as follows: residual volume, 1.26 +/- 0.13 ml; FRC, 2.51 +/- 0.20 ml; total lung capacity, 12.23 +/- 0.55 ml; compliance of the lung, 0.90 +/- 0.06 ml/cmH2O; chest wall compliance, 1.50 +/- 0.11 ml/cmH2O; and respiratory system compliance, 0.57 +/- 0.03 ml/cmH2O. The lung PV curve did not show a consistent change after the chest was opened.

Age-related and light-associated retinal changes in Fischer rats

Morphological changes in retinas of aging Fischer 344 rats were characterized. The numbers of photoreceptor cells gradually decreased as rats aged. The outer nuclear layer was 12 cells thick at 3 months, but was reduced to less than 8 cells by 18 months. The decrease of photoreceptor cells was more pronounced in rats housed under a light intensity of 32-ft-c than in rats housed under a light intensity of 1 ft-c. Inner and outer segments of surviving photoreceptor cells were morphologically normal. A new form of retinal degeneration was discovered in aged Fischer rats characterized by selective degeneration of peripheral retina. Degeneration was characterized by severe loss of photoreceptor cells in the far peripheral retina. Microcystoids were found in about 25% ofthe affected retinas, and the loss of photoreceptor cells was followed by proliferation and vascularization of the retinal pigment epithelium and disorganization of retinal structures. The incidence and severity of peripheral retinal degeneration increased with aged and prolonged exposure to comparatively high-intensity light. All Fischer rats ((5/5) housed under light intensity of 32 ft-c developed severe peripheral retinal degeneration by 24 months. Peripheral retinal degeneration was an age-related change but appeared to be exaggerated by ambient light.

Rat model for hereditary retinal degeneration

The disorder in Wag/Rij rats is a spontaneous, bilateral retinal deneration. It is characterized by an early onset, slowly progressive degeneration of the photoreceptor cells leading to destruction of the retina. Degeneration affects both rod cells and cone cells, and to a lesser degree the cells in the inner nuclear layer. The remarkable alterations in the retinal pigment epithelium during the course of the disease suggest a profound change in metabolism and function of the pigment epithelium and implicate a possibility of interaction between the pigment epithelium and the photoreceptors. Since degenerated cells have also been observed in the inner nuclear layers, there is a possibility that Muller's cells are involved in the retinal degeneration. Controlled experiments have demonstrated that the disease is not induced by light damaging effects of the retina, and initial breeding experiments suggest that the disease is inheritable, probably as an autosomal dominant trait. The retinal degeneration in Wag/Rij rats is a new, unique system and it is a potentially very useful animal model of retinitis pigmentosa.

Esophageal elastance in awake and anesthetized recumbent dogs

Esophageal elastance was measured in trained dogs placed in the prone, supine, and left lateral postures before and during sodium thiopental anesthesia. Esophageal elastance was measured from static pressure-volume curves and during spontaneous breathing at functional residual capacity. There was a significant decrease in esophageal elastance, estimated from the pressure-volume curves, during anesthesia in both prone and lateral positions but not in the supine posture. Changes in vagal tone produced by stimulation of the vagal nerves did not alter esophageal elastance. Therefore, underlying mechanisms for these changes in esophageal elastance are not fully understood. There was an increase in esophageal elastance when lung volumes increased from 55 to 80% total lung capacity. However, we did not find a significant change in esophageal elastance between awake and anesthetized conditions or between positions during spontaneous breathing at functional residual capacity.

Keratoconjunctivitis associated with sialodacryoadenitis in rats

A high incidence of keratoconjunctivitis was observed in a closed colony of inbred Lewis/Wistar rats. Clinical signs including blinking, ocular discharge, circumcorneal flush, corneal opacity, ulceration, pannus, hypopyon, and hyphema were observed at about three weeks of age. Acute disease subsided by six weeks of age, but some lesions progressed to low-grade chronic keratitis. Six per cent of affected rats developed megaloglobus, which usually appeared by three weeks of age. Lesions included focal or diffuse interstitial keratitis, corneal ulceration, anterior synechia, and inflammatory exudate in the anterior chamber. A high incidence of lenticular and retinal degeneration was associated with megaloglobus. Most affected rats also had harderian dacryoadenitis. Sialodacryoadenitis virus (SDA) was recovered from nasal washes, but not from affected eyes. Serological evidence indicated that SDA virus infection was widespread in the colony.

A new form of hereditary retinal degeneration in Wag/Rij rats

A spontaneous, hereditable, bilateral retinal degeneration affecting all adult animals in a closed, imbred colony of Wag/Rij rats has been discovered. The disorder is characterized by early onset and a slow progressive course. Early lesions are detected by one month in retinas which are otherwise fully developed. Destruction of the photoreceptor layer proceeds as more and more cells degenerate. Degeneration appears to begin in the photoreceptor cell body and only secondarily affects the outer segment. Futhermore, phagocytic activity of pigment epithelium remains intact until late in the disease. Endstage lesions include retinal disorganization, proliferation and vascularization of pigment epithelium, and migration of pigment epithilial cells into the retina. The temporal and structural characteristics of this retinopathy indicate it may serve as a useful model for study of retinitis pigmentosa in man.