Tachykinins in propranolol-augmented, hyperpnoea-induced bronchoconstriction in Taida guinea-pigs: effects of dimethylthiourea

1. The present authors recently found that a marked hyperpnoea-induced bronchoconstriction (HIB) only occurred in guinea-pigs after treatment with propranolol, a non-selective beta-adrenoceptor antagonist. This study investigated tachykinin-dependent and antioxidant-modulated mechanisms for this propranolol-augmented HIB. 2. Guinea-pigs were pre-treated with an antioxidant, dimethylthiourea (DMTU), or saline for 3 days. On the day of study, each animal was given a dose of propranolol (0.5 mg kg(-1)), then the airway function was examined in the anaesthetized-paralysed animal before, during and after hyperpnoea with a dry 95% O2:5% CO2 gas mixture. Tracheal neutral endopeptidase (NEP) activity and plasma substance P (SP) level were measured after functional study. 3. In the presence of propranolol, HIB was augmented, and was found to be associated with decreased NEP activity and an increased plasma SP level. The augmented HIB was attenuated by DMTU. 4. Therefore, the present results suggest that propranolol-augmented HIB is tachykinin-dependent and is modulated by DMTU.

Standards of birth weight in twin gestations stratified by placental chorionicity

OBJECTIVE

To establish fetal growth nomograms for twin gestations, categorized by placental chorionicity, and to compare them with those of published singleton and twin nomograms.

METHODS

Computerized data files of live births of all twins delivered between January 1990 and October 1996 at Saint Peter's Medical Center were used. Birth weight curves corresponding to the fifth, tenth, 50th, 90th, and 95th percentiles were derived separately for twins with monochorionic and dichorionic placentation. We generated the curves by applying the method of generalized estimating equations, after adjusting for the potential intracluster correlation due to twinning. The curves were then smoothed on the basis of nonparametric restricted cubic splines to derive (smoothed) birth weight percentiles. We then compared our twin birth weight nomogram to six previously published singleton and two twin nomograms published previously for predicting small for gestational age infants (defined as birth weight below the tenth percentile).

RESULTS

Among 1302 twin fetuses, 272 (21%) were monochorionic. Twins from monochorionic gestations weighed, on average, 66.1 g (standard deviation 28.4 g, P = .02) less than twins from dichorionic gestations after correcting for gestational age. Twin curves based on parity (nulliparity versus multiparity) were not different from each other. Analyses indicate that all previously published singleton nomograms approximate twin growth reasonably well between 32 and 34 weeks, but they underestimate twin growth at earlier gestational ages (between 25 and 32 weeks) and overestimate twin growth beyond 34 weeks' gestation. Similarly, a comparison of previously published twin nomograms with those of ours indicates that the growth standards in our population were similar to those in other published twin nomograms.

CONCLUSION

We recommend that future epidemiologic and clinical studies use twin nomograms to identify growth-restricted twin fetuses. Moreover, because fetal growth is influenced by placental chorionicity, we recommend that fetal growth assessment in twin gestations consider placental chorionicity, whenever the information is available.

Attenuation of isocapnic hyperpnoea-induced guinea-pig bronchoconstriction by chronic hypoxia

Chronic hypoxia has been shown to augment the production of antioxidants in rat lungs and to reduce airway hyperreactivity in patients with asthma. This study investigated indirectly whether this increase in antioxidants occurs in guinea-pig lungs and whether the increased antioxidants affect hyperpnoea-induced bronchoconstriction (HIB). Guinea-pigs were divided into four groups: control (n=8); chronic hypoxia (n=7); capsaicin pretreatment (n=7); and capsaicin pretreatment plus chronic hypoxia (n=8). Control animals were not treated. Animals in the hypoxia group were intermittently exposed to an ambient pressure of 380 mmHg for 7 days. A five day pretreatment of capsaicin was used to deplete tachykinins. In the last group, animals were pretreated with capsaicin, followed by a seven day hypoxic exposure. On the day of the study, airway function was examined in the anaesthetized and paralysed animal. Fifteen minutes of hyperpnoea caused marked decreases in the maximal expiratory flow rate at 15% vital capacity, forced expiratory volume in one second, and dynamic respiratory compliance, indicating HIB. This HIB and plasma substance P levels were significantly attenuated by chronic hypoxia, capsaicin pretreatment, and capsaicin pretreatment plus chronic hypoxia. Furthermore, chronic hypoxia attenuated airway constriction induced by xanthine-xanthine oxidase. The results suggest that chronic hypoxia attenuates hyperpnoea-induced bronchoconstriction via a decrease in the oxygen radical-mediated release of tachykinins.

Effects of an abdominal binder and electrical stimulation on cough in patients with spinal cord injury

We explored the effect of an abdominal binder, with or without electrical stimulation, on peak expiratory flow rate (PEFR) in 12 paraplegics with complete thoracic cord (T2-T12) injury (mean age 36.0 +/- 1.5 yr) and 12 quadriplegics with complete cervical cord (C4-C8) injury (mean age 36.2 +/- 1.9 yr). The cough was assessed by measuring the PEFR during forceful expiration in a sitting position. The subjects underwent the following experimental maneuvers in a random order with a 10-minute interval between any two maneuvers: 1) voluntary coughing, 2) voluntary coughing with an abdominal binder, and 3) voluntary coughing with an abdominal binder and electrical stimulation. The electrical stimulator (50 Hz with 300 microseconds pulse width) was applied to the abdominal wall. Data were analyzed using multivariate analysis of variance for repeated measures. The abdominal binder did not significantly increase PEFR in either paraplegics or quadriplegics; the abdominal binder combined with electrical stimulation significantly increased PEFR by 15% in the paraplegics and 18% in the quadriplegics. These results indicate that electrical stimulation combined with an abdominal binder improves the cough ability in patients with cervical or thoracic spinal cord injury.

Photodynamic therapy for facial squamous cell carcinoma in cats using Photofrin

BACKGROUND

Photodynamic therapy (PDT) has been shown to be an effective treatment modality for surface-oriented neoplasms of the skin, respiratory, gastrointestinal, and urogenital systems. The purpose of our study was to assess the safety and efficacy of PDT using Photofrin in the treatment of squamous cell carcinomas of feline facial skin.

MATERIALS AND METHODS

Cats with naturally occurring squamous cell carcinomas of the skin were entered into the study. PDT was delivered to the tumors using an argon-pumped dye laser 48 hours after the administration of the photosensitizer porfimer sodium (Photofrin). Following treatment, the tumors were evaluated for complete response rates and local control durations.

RESULTS

Eight tumors were staged T1a, 9 staged T1b, and 14 staged T2b. Complete response rates as well as local control durations were significantly related to stage (p < 0.0001). Complete response was achieved in 100% of the T1a tumors and 53% of the T1b tumors; the overall 1-year local control rate for all treated tumors was 62%. Clinical, hematological, and biochemical evidence of toxicity was not seen in any cat following drug administration.

CONCLUSION

PDT with the photosensitizer Photofrin was safe and effective in treating early stage squamous cell carcinomas of the feline skin.

Induction of apoptosis in human leukemic U937 cells by tetrandrine

Tetrandrine, a calcium channel antagonist, is a plant alkaloid possessing various pharmacological activities including anti-tumor activity. We studied tetrandrine to determine whether or not this anti-tumor effect occurs through induction of apoptosis. Tetrandrine inhibited both proliferation and clonogenicity of human leukemic U937 cells at an optimal concentration of 2.5 microg/ml. This growth inhibition was dose and time dependent, and accompanied with evidence of apoptotic changes. The characteristic morphological changes of apoptosis were observed in U937 cells under light microscopy and DNA fragmentation was noted by gel electrophoresis. Moreover, flow cytometric detection of surface phosphatidyl serine expression of U937 cells after treatment with tetrandrine confirmed the induction of apoptosis in these cells. The induction of apoptosis by tetrandrine would appear to proceed via non-Ca2+-dependent pathways.

Antenatal prediction of fetal pH in growth restricted fetuses using computer analysis of the fetal heart rate

We tested the accuracy of a mathematical model based on computer analysis of the fetal heart rate tracing in predicting umbilical artery pH at birth. In a previous report based on data on 38 growth-restricted fetuses, the second-order polynomial regression equation, umbilical artery pH = 7.28 + 0.002 (duration of episodes of low variation in minutes) + 0.00009 (duration of episodes of low variation in minutes), was retrospectively found to be the best model for the prediction of umbilical artery pH at birth. In the present study, this formula was prospectively tested in 29 growth restricted fetuses between 26 and 37 weeks of gestation from pregnancies with abnormal uterine and/or umbilical artery Doppler velocimetry. Computer analysis of the fetal heart rate tracing of 1 hour duration was performed within 1.5-6 hours of cesarean birth prior to the onset of labor. Umbilical artery cord blood was collected at birth with pH determined within 5 minutes of collection. Acidemia was defined as umbilical artery pH < 7.20, preacidemia pH 7.20-7.25 and nonacidemia pH > 7.25. Then, the data on all 67 growth-restricted fetuses were pooled to generate a new formula that was retrospectively assessed against the entire group. Values are reported as median (range). In the 29 prospectively evaluated cases, there was no statistical difference between the predicted and actual umbilical artery pH at birth [7.28 (7.1-7.29) vs. 7.28 (7.18-7.37), P = 0.57]. The median difference between the paired predicted and actual umbilical artery pH values was -0.001 (-0.10-0.08). The difference between the predicted and actual umbilical artery pH was zero and within +/- 0.04 in 17% (5/29) and 76% (22/29) of the cases, respectively. When the data on the 67 growth-restricted fetuses were pooled together the formula did not change. There was no difference between the predicted and actual umbilical artery pH at birth when the formula was applied to all 67 growth-restricted fetuses [7.28 (7.08-7.29) vs. 7.27 (6.97-7.37), P = 0.41]. The median difference between the paired predicted and actual pH values was -0.001 (-0.12-0.12). The difference between the predicted and actual umbilical artery pH was zero and within +/- 0.04 in 15% (10/67) and 74% (49/67) of the cases, respectively. The accuracy of the formula in correctly categorizing the umbilical artery pH at birth was: acidemia 67% (8/12), preacidemia 28% (8/29) and nonacidemia 80% (37/46), P < 0.0001. A mathematical formula using the computer analysis index of duration of episodes of low variation reliably predicted umbilical artery pH at birth. This type of noninvasive monitoring may allow for the antepartum estimation and continuous tracking of fetal pH.

Protective effect of tetrandrine on normal human mononuclear cells against ionizing irradiation

Tetrandrine, an alkaloid isolated from the plant Stephania tetrandra, at low concentration (2 micrograms/ml) was shown to protect normal human mononuclear cells in vitro against damage due to a single high-dose of ionizing irradiation (10 Gy). The cell survival rate increased from 58.3 +/- 2.2% in the irradiated group to 78.0 +/- 2.6% in the tetrandrine-pretreated group, and similarly, the percentage of necrotic cells declined from 20.7 +/- 2.5% to 10.7 +/- 1.9%, respectively. This protective effect of tetrandrine for cell surviving fraction increased in a dose-dependent manner. Tetrandrine was also found to inhibit inflammatory responses induced by irradiation including the release of superoxide (NBT [nitroblue tetrazolium] reduction decreased from 21.3 +/- 2.3% to 10.2 +/- 2.5%) and phagocytic activity (decreased from 80.7 +/- 3.8% to 50.7 +/- 2.3%, the same range level as that of the control group). However, the alkaloid demonstrated no effect on the production of nitric oxide. In terms of cell morphology, only two types were observed-normal or necrotic cells, and there were no characteristics of programmed cell death. These results indicate that tetrandrine possesses radioprotective activity against 10 Gy of ionizing irradiation and could suppress irradiation-induced inflammatory processes.

Lung tissue resistance measured in saline-filled guinea pig lungs by micropuncture

Lung tissue resistance (Rti) measured in air-filled guinea pig lungs by the alveolar capsule technique was a large part of total lung resistance (Rl), and we wondered whether similar results applied to saline-filled lungs. We used the micropuncture method to measure alveolar pressure (Palv) in saline-filled lungs of 21 guinea pigs. Palv and airway opening pressure (Pao) were measured before and after a sudden interruption of flow during an inflation or deflation maneuver. On stopping flow, there was an immediate large change in Pao followed by a smaller slower change in Pao. Palv was nearly constant immediately after flow interruption but followed the slower change in Pao. The initial change in Pao on flow interruption was interpreted as the resistive pressure loss in the airways. The small change in Pao and Palv was interpreted as the pressure loss caused by tissue stress adaptation. Airway resistance (R(aw)) and Rti were obtained by dividing the pressure losses by the flow before the interruption. Rl was the sum of R(aw) and Rti. The calcium blocker nifedipine reduced both R(aw) and Rti and abolished the difference in Rti between inflation and deflation. Values of Rti were 10-29% of Rl. However, with correction for viscosity, Rti predicted in air-filled lungs would dominate Rl.

Palliative medicine and the hospice movement in Taiwan

Taiwan is an island country, with a small area and a dense population. Cancer has been the leading cause of death for over 15 years, and the number of cancer deaths is increasing year by year. The hospice movement started in 1983, and the first hospice was set up in 1990. There are more than ten hospices at present. Three foundations and one other organization have joined in with the hospice movement. The capacity of the hospice service cannot meet the needs for care. Education together with training is becoming necessary. Research is highlighted with an indigenous model. The curriculum for palliative medicine has recently been confirmed for education in the future. The Government has been a great help in the development of palliative care, and more service needs are identified. The situation with the hospice movement in Taiwan is positive and promising.

Water-soluble fullerene derivatives attenuate exsanguination-induced bronchoconstriction of guinea-pigs

1. This study investigated the effects of increased antioxidants (administration of water-soluble fullerenol-1 and pre-exposure to chronic hypoxia) as well as an iron-chelating agent (deferoxamine) on exsanguination-induced noncholinergic airway constriction in guinea-pigs. 2. Fullerenol-1 usually did not cause significant alteration in respiratory function (lung volumes, dynamic respiratory compliance, maximal expiratory flow at 50% total lung capacity (Vmax50), and forced expiratory flow at 0.1 s (FEV 0.1) at low (200 micrograms kg-1) or at high doses (2 mg kg-1), except that it produced a slight bronchial constricting action (decreases in both Vmax 50 and FEV 0.1) at high doses (2 mg kg-1) via intratracheal instillation. 3. Beginning 15 min after exsanguination, there was a marked temporal decrease in FEV 0.1, indicating a gradual increase in airway constriction with time. 4. Administration of either fullerenol-1 or deferoxamine, or pre-exposure to chronic hypoxia significantly ameliorated the exsanguination-induced bronchoconstriction. The results provide evidence that oxygen radicals play an important role in exsanguination-induced airway constriction. 5. The significant effects of the increased antioxidants and deferoxamine,however, cannot be explained by the alteration in either tracheal neutral endopeptidase activity or lung tissue substance P level.

Relationship of insulin resistance and hyperinsulinemia to blood pressure during pregnancy

The purpose of our study was to examine the relationship between insulin resistance and blood pressure during pregnancy and to determine to what extent insulin resistance is related to the subsequent development of pregnancy-induced hypertension. The study population consisted of 292 women who had serum insulin, glucose and insulin-glucose ratios determined at 26-28 weeks gestation in a fasting state and 1 hr after a 50-g oral glucose challenge. These were compared with blood pressures at 26-28 weeks gestation and in the late third trimester. A statistically significant correlation exists overall between (1) blood pressure at 26-28 weeks gestation and both fasting insulin and insulin-glucose ratios, as well as (2) systolic blood pressure at term and fasting insulin levels. However, when controlled for confounding variables including body mass index, race and age, no statistically significant relationship remained. The metabolic variables in patients with pregnancy-induced hypertension were not statistically different from the normotensive patients. In conclusion, this study demonstrates that insulin resistance and hyperinsulinemia are not major determinants of blood pressure during pregnancy.

Pulmonary mechanical and immunologic dysfunction in a murine model of AIDS

Human immunodeficiency virus-infected patients occasionally exhibit alveolar septal wall thickening and decreases in gas diffusion capacity, but the mechanism underlying these abnormalities is unknown. The present study evaluated septal wall thickness and gas exchange properties in a murine model of the acquired immunodeficiency syndrome and determined whether there were alterations in lung lymphocyte deposition and activation that could contribute to changes in respiratory structure and function. Although alveolar septal wall thickness did not differ from control at 1, 2, and 4 wk postimmunosuppressive virus infection, at 8 wk after infection, septal wall thickness was substantially increased. Immunohistochemical evaluation at this time revealed marked increases in the septal wall deposition of fibronectin and collagen type IV. Pulmonary function tests on anesthetized mice with virus-induced septal wall thickening demonstrated that, although total lung capacity, compliance, and functional residual capacity were unaltered, diffusion capacity for carbon monoxide was significantly impaired. A diffuse nonspecific interstitial pneumonitis was present in lungs of immunodeficient mice, and flow cytometry indicated that both lymphocytes and macrophages were activated. Reverse transcriptase-polymerase chain reaction analysis of lung lymphocytes demonstrated enhanced mRNA expression for several cytokines known to affect lung structure. These results show that impaired gas exchange occurs in a murine model of acquired immunodeficiency syndrome and suggest that such alterations may be mediated by elaboration of cytokines from activated lung lymphocytes and macrophages.

Comparison of five measures derived from in vivo pulmonary vascular pressure-flow curves

In order to facilitate evaluation of acute changes in lung vascular characteristics in vivo, pressure-flow (delta P-Q) curves of the pulmonary circulation were obtained by step-wise flow reduction. A balloon-tipped Swan-Ganz catheter was inserted via the jugular vein into the inferior vena cava of anesthetized, open chest, ventilated rabbits. Pulmonary arterial (Ppa) and left atrial (Pla) pressures were measured via catheters, and cardiac output Q by an electromagnetic flow probe on the aorta. Inflation of the balloon for 10 s reduced Q by 30-70%. delta P-Q curves were constructed by plotting a series of values of Q against corresponding delta P (= Ppa-Pla). To evaluate the feasibility and sensitivity of the method, these curves were compared under three conditions each paired with control (normoxia): hypoxia (8% O2), isoproterenol infusion, and serotonin infusion. Within our measured flow ranges, most delta P-Q plots were fairly linear, and extrapolated to a positive delta P intercept. Comparing slope, intercept, resistance, delta P at fixed Q, and Q at fixed delta P, we found that the latter two provided the more sensitive index to differentiate vasomotor changes. Since delta P-Q curves generally miss the origin, calculated pulmonary vascular resistance must depend on Q. Therefore, using the shifts in entire delta P-Q curves to select common range of Q and/or delta P is in general more quantitatively reliable for defining altered vascular characteristics.

Eglin-c prevents monocrotaline-induced ventilatory dysfunction

The present study was carried out to investigate the relationship between elastase and monocrotaline (MCT)-induced ventilatory dysfunction in rats. To accomplish this, we used an elastase inhibitor eglin-c to suppress the activity of endogenous elastase. Thirty-five young Sprague-Dawley rats were randomly divided into six groups: control, MCT, eglin-c(1), eglin-c(2), eglin-c(1) + MCT, and eglin-c(2) + MCT. Rats in the control group received no treatment. Each MCT rat received a single subcutaneous injection of MCT (60 mg/kg) 1 wk before the functional test. Each eglin-c(1) rat was intratracheally instilled with eglin-c (9 mg/rat) twice in 1 wk. Each eglin-c(2) rat was intratracheally instilled with eglin-c (9 mg/rat) five times in 1 wk. Both eglin-c + MCT groups were treated with the combination of eglin-c(1) or eglin-c(2) and MCT. In the MCT group, there were significant decreases in dynamic respiratory compliance, maximal expiratory flow rate at 50% total lung capacity, and the slopes of the maximal expiratory flow-%total lung capacity curve and the maximal expiratory flow-static recoil pressure curve. However, in the eglin-c(1) + MCT and eglin-c(2) + MCT groups, all of the above-mentioned MCT-induced changes were prevented. All ventilatory values of the eglin-c(1) and eglin-c(2) groups were not significantly different from those of the control group. These results demonstrate that eglin-c treatment prevents MCT-induced ventilatory dysfunction and suggest that endogenous elastase may play an important role in MCT-induced inflammation-mediated ventilatory abnormality.

Experimental asthma developed by room air contamination with cockroach allergen

To study the asthmatogenic effect of certain airborne elements of the home environment, we studied a group of guinea pigs exposed to aerosolized cockroach allergen (CRa) and side-stream cigarette (S-SC) smoke. Four groups of guinea pigs were exposed to aerosols, either saline or CRa, for 4 weeks, after a sham or S-SC smoke pretreatment. Anaphylactic antibodies were measured by passive cutaneous anaphylaxis (PCA) assay and by skin test. Animals were challenged with aerosol CRa on day 35, and lung function and leukotrienes (LTB4 and LTC4/D4) were measured. Skin tests were positive on days 21 and 29. The antibodies were heat-stable, IgG1a-like antibodies (PCA titers 1:2-18). The CRa challenge caused an immediate reduction in both the maximal expiratory flow rate at 50% of the lung capacity and respiratory compliance. The decreased lung function continued for up to 6 h (p < 0.0001). LTB4 and LTC4/D4 were elevated (p < 0.0001) in the sensitized animals at the corresponding times of reduced lung function. S-SC smoke did not affect the CRa sensitization; instead, a protective effect on the CRa-induced bronchospasms was noted. Thus, the study indicates that a simple airborne CRa exposure without an adjuvant sensitizes guinea pigs, and that the animals respond to antigen challenge with CRa-specific airway obstructions.

Efficacy of tracheal gas insufflation in acute respiratory distress syndrome with permissive hypercapnia

This study was conducted to assess the CO2-elimination efficiency of tracheal gas insufflation (TGI) in 20 patients with acute respiratory distress syndrome and to compare its efficacy during volume-controlled (VCV) and pressure-controlled ventilation (PCV). TGI was initially applied as an adjunct to VCV, with continuous flows (Vcath) of 4 and 6 L/min delivered through a catheter positioned 2 cm above the carina. Total effective tidal volume (VTeff) was held constant. The percent reductions in PaCO2 (% delta PaCO2) were 13.3 +/- 2.1 and 16.7 +/- 2.7% at Vcath 4 and 6 L/min, respectively, which correlated well with the percent reduction in the end-tidal PCO2 from baseline (% delta PETCO2) (r = 0.75, p < 0.001). An inverse relationship (r = -0.65, p < 0.001 and r = -0.59, p < 0.01 at Vcath 4 and 6 L/min, respectively) was found between the % delta PaCO2 and the baseline ratio of artery to PETCO2 difference to PaCO2, which was determined as the fraction of alveolar dead space (VDalv) relative to total alveolar ventilation. Twelve patients were subsequently switched to PCV combined with Vcath 6 L/min, which provided a % delta PaCO2 of 16.1 +/- 3.0% (p = NS versus 17.1 +/- 2.6% during VCV). These data suggest that in patients with ARDS the change in PETCO2 may be helpful in predicting the decrement in PaCO2 during TGI, and the existence of a high VDalv tends to limit its effectiveness. Further, the efficacy of TGI with VCV is equivalent to that with PCV.

Nipple reduction with a modified circumcision technique

Several methods of reduction of the hypertrophic nipple have been reported. All of them have some drawbacks. We propose a technique that can be easily performed and can produce excellent aesthetic as well as good functional results.

Oxygen radicals in the nonvagal component of noncholinergic airway constriction

To test the hypothesis that oxygen radicals play an important role in the nonvagal component of the noncholinergic bronchoconstriction in vivo, 37 guinea pigs weighing 329 +/- 8 g were randomly divided into five groups: group 1, vagotomy; group 2, vagotomy + CAT (catalase); group 3, vagotomy + SOD (superoxide dismutase); group 4, vagotomy + PBN (alpha-phenyl-N-tert-butyl nitrone); and group 5, capsaicin pretreatment. CAT, SOD, and PBN are antioxidants. Each animal was anesthetized, paralyzed, artificially ventilated, and pretreated with atropine and phenoxybenzamine. Immediately after acute capsaicin challenge, animals in group 1 exhibited decreases in maximal expiratory flow, dynamic respiratory compliance, and total lung capacity, as well as an increase in functional residual capacity, indicating noncholinergic airway constriction. The bronchoconstriction was significantly ameliorated by SOD and PBN, and it was almost abolished by capsaicin pretreatment. Thirty minutes after acute capsaicin challenge, there was a significant decrease in airway NEP activity and an increase in lung substance P level in group 1 but not in other groups. These results indicate that nonvagal component of noncholinergic bronchoconstriction is partially modulated by oxygen radicals.

Amiodarone-induced pulmonary fibrosis in Fischer 344 rats

Amiodarone is a potent antiarrhythmic agent with a number of side-effects, the most serious being the development of pulmonary toxicity. The purpose of the study was to determine if a single intratracheal instillation of amiodarone would induce pulmonary fibrosis and associated functional changes in rats. Female Fischer 344 rats were given a single intratracheal instillation of 200 microliters containing 1.25 mg amiodarone (n = 9) while the control group received an equivalent volume of sterile water (n = 8). After 6 weeks, pulmonary function tests, lung hydroxyproline measurements and lung histology were performed. The amiodarone-treated animals showed a significant reduction in the coefficient of diffusion (kCO) and a significant increase in lung hydroxyproline levels as compared to the control group. The treated group had abnormal histology including areas of septal thickening with cellular infiltration of the interstitial and alveolar spaces, whereas the control group had normal histology. These observations suggest that the intratracheal instillation route of amiodarone treatment produces a fibrotic response in rats that can be measured physiologically, biochemically and histologically. This model may aid in the elucidation of the mechanism of amiodarone-induced pulmonary toxicity (AIPT)./ABS.

Immunoprophylaxis of allergen-induced immunoglobulin E synthesis and airway hyperresponsiveness in vivo by genetic immunization

The efficacy of an "allergen-gene immunization" protocol in altering allergic response was examined. Intramuscular injection of rats with a plasmid DNA encoding a house dust mite allergen into the muscle results in its long-term expression and the induction of specific immune responses. Significantly, this approach prevents the induction of immunoglobulin E synthesis, histamine release in bronchoalveolar fluids, and airway hyperresponsiveness in rats challenged with aerosolized allergen. Furthermore, this suppression is persistent and can be transferred into naive rats by CD8+ T cells from gene-immunized rats. These findings suggest that allergen-gene immunization is effective in modulating allergic responses, and may provide a novel therapeutic approach for allergic diseases.

Renal neural response to ischemic renal failure in chronic hypoxic rats

This report was designed to assess response of the renal nerve activity (RNA) during and after renal ischemia in chronic hypoxic rats. Hypoxia was induced by placing the female Wistar rats in an altitude chamber set at 5500 m for 4 weeks. Simultaneous recordings of left renal efferent (RENA) and afferent (RANA) nerve activity were performed in each pentobarbital-anesthetized rat throughout the experiment. Ischemic renal failure was induced by complete occlusion of the left renal artery for 45 min. During renal arterial occlusion (RAO), RENA gradually decreased while RANA enhanced initially and then this decreased gradually in both sea level (SL) controls and chronic hypoxic (high-altitude; HA) rats. During 45 min of reperfusion, RENA depressed more in comparison with RANA in both groups of animals. In addition, RANA returned to baseline level in SL rats, while it remained elevated in HA rats. In the second experiment, six groups of renal ischemic rats were challenged by rapid intravenous infusion of 10 ml of saline, and urine was collected for 90 min from the left ureter. Baseline RENA was low in rats 4 h after RAO of SL (4SL) and of HA (4HA) groups. The effects of saline loading on RENA and RANA were different in HA and SL rats. Saline loading significantly decreased RENA but increased RANA more in SL rats. Following saline loading, RENA in 4SL and 4HA rats, as well as animals 24 h after RAO of SL (24SL) and HA (24HA) were comparable to their respective SL or HA animals. In 4SL rats, RANA was significantly enhanced, and remained elevated during saline loading and the recovery period. In 4HA, 24HA and 24SL rats, RANA reduced significantly during saline loading, then its activity returned to the baseline value. The insulted kidneys showed increased renal excretion of water and sodium in 4SL and 4HA rats. Urinary excretion reduced significantly in 24SL rats but was almost normal in 24HA rats. These results indicate that a decrease in RENA may play a protective role in response to renal ischemia in both SL and HA rats. In response to renal ischemia and saline loading, different alterations of RANA in SL and HA rats may reflect a beneficial mechanism located in the hypoxia-pretreated kidney.

Diminished Tc-99m HMPAO pulmonary uptake in ex-smokers

Normally, there is no localization of Tc-99m HMPAO in the lungs. Tc-99m uptake in smokers' lungs has been reportedly higher than in nonsmokers. Thus, the lung uptake may be used as a barometer of cigarette smoking. To assess whether there is a decrease in pulmonary uptake of Tc-99m HMPAO after cessation of smoking, the authors investigated the lung uptake of 31 male ex-smokers in comparison to smokers and nonsmokers. Anterior and posterior images were taken 10 minutes after intravenous injection of 20-25 mCi of Tc-99m HMPAO. Regions-of-interest over the liver and lungs in the anterior view were calculated. Duration of abstinence from smoking ranged from 5 months to 50 years. The mean lung/liver uptake in ex-smokers was 0.489 +/- 0.019 (sem). In a previous report, the mean lung/liver ratio for smokers (N = 30) was 0.805 +/- 0.040 (sem) and 0.408 +/- 0.019 (sem) for nonsmokers (N = 25). Compared with smokers, the lung/liver uptake ratio of ex-smokers was significantly lower (P < 7 x 10(-9)). The lung/liver uptake ratio of ex-smokers was significantly higher than that of nonsmokers (P < 0.005). The authors conclude that pulmonary Tc-99m HMPAO uptake of smokers is significantly diminished after quitting smoking. However, the lung uptake of ex-smokers is higher than that of non-smokers. The uptake in the lung induced by smoking appears to be partially reversible after the cessation of smoking.