A review of chronic inhalation studies with mainstream cigarette smoke in rats and mice

In this paper, I review the results of a representative selection of chronic inhalation studies with rats and mice exposed to mainstream cigarette smoke and describe the inhalation exposures and the histopathological changes reported by various authors. Many of the studies used nose-only exposure systems, whereas others simply used large whole-body chambers. Smoke-induced epithelial hypertrophy, hyperplasia, and squamous metaplasia were reported in the conducting airways in most of the studies, along with increased numbers of intra-alveolar macrophages that were occasionally associated with alveolar metaplasia. Lung adenomas and adenocarcinomas were reported in only a few of the studies. No statistically significant increase in the incidence of malignant lung tumors was seen in either species as a result of smoke exposure, a finding that does not agree with the results of epidemiological studies in humans. Possible reasons for this lack of correlation are given.     

Pharmacokinetics of hydroxocobalamin in smoke inhalation victims

PURPOSE: This study was performed to describe the clinicopathologic features of a group of patients with posttraumatic unilateral focal choroidal granulomatous inflammation. METHODS: Enucleated eyes with focal choroidal granulomatous inflammation without clinical signs of contralateral ocular inflammation were identified. Clinical and pathologic features were recorded. RESULTS: Six enucleated eyes that had been injured by projectiles had focal uveal granulomatous inflammation of the posterior choroid. Four eyes had uvea attached to or incarcerated into the wound. Two eyes had foreign material associated with the granulomatous inflammation, and two eyes had a disrupted lens with lens-induced inflammation. Two eyes exhibited the focal granulomatous inflammation at the site of a choroidal rupture. None of the six enucleated eyes contained Dalen-Fuchs' nodules. CONCLUSIONS: Focal choroidal granulomatous inflammation may occur as a result of penetrating ocular trauma. The origin of this condition is unknown, although it likely represents a reaction to a foreign body.     

Heparin improves oxygenation and minimizes barotrauma after severe smoke inhalation in an ovine model

Inhalation injury is one of the main causes of mortality in burn victims. The tracheobronchial epithelium sloughs and combines with a protein rich exudate to form casts of the airways that can lead to obstruction. We studied the effects of a continuous infusion of heparin on the acute pulmonary injury that occurs after smoke inhalation injury in sheep. Twelve ewes with vascular catheters received a standardized smoke inhalation injury and mechanical ventilation according to protocol for 72 hours. The heparin group (n = 6) received a 400 unit per kilogram bolus of heparin followed by a continuous infusion to maintain the activated clotting time between 250 to 300 seconds. The control group (n = 6) received a saline solution vehicle. Hemodynamics, blood gases and plasma samples for conjugated dienes were taken every six hours. At necropsy, pulmonary tissue was collected for histologic findings, polymorphonuclear neutrophil leukosequestration, wet-to-dry weight ratios and conjugated dienes. PaO2 to FIO2 ratios were improved in the heparin group compared with the control group at 12 to 72 hours after injury, and peak airway pressures were higher in the control group compared with the heparin group. Positive end expiratory pressure requirements were higher in the control group compared with the heparin group. There were significantly fewer airway tracheobronchial casts as determined by our tracheobronchial casts scoring system (2.4 +/- 0.4 versus 0.67 +/- 0.21) and confirmed by histologic examination. Pulmonary blood-free wet-to-dry weight ratios were higher in the control group compared with the heparin group (6.4 +/- 0.5 versus 5.2 +/- 0.1; p < 0.05). There were no differences in pulmonary tissue or plasma conjugated dienes; likewise, pulmonary leukosequestration was unaffected by heparin. Heparin decreases tracheobronchial cast formation, improves oxygenation, minimizes barotrauma and reduces pulmonary edema in an ovine model of severe smoke inhalation injury. Heparin does not reduce oxygen free radical activity after smoke inhalation injury.     

Effect of reduced bronchial circulation on lung fluid flux after smoke inhalation in sheep

Murine monoclonal antibodies directed against proteins of Borrelia burgdorferi B31 (low passage) were generated by the administration of antigen via the bite of borrelia-infected ticks. This strategy was employed as a mechanism to create antibodies against antigens presented by the natural route of tick transmission versus those presented by inoculation with cultured borreliae. One of the resultant antibodies reacted with a 17-kDa antigen from cultured B. burgdorferi, as seen by immunoblot analysis. This antibody was used to screen a B. burgdorferi genomic DNA lambda vector expression library, and an immunoreactive clone was isolated. DNA sequence analysis of this clone, containing a 2.7-kb insert, revealed several open reading frames. These open reading frames were found to be homologs of genes discovered as a multicopy gene family in the 297 strain of B. burgdorferi by Porcella et al. (S. F. Porcella, T. G. Popova, D. R. Akins, M. Li, J. D. Radolf, and M. V. Norgard, J. Bacteriol. 178:3293-3307, 1996). By selectively subcloning genes found in this insert into an Escherichia coli plasmid expression vector, the observation was made that the rev gene product was the protein reactive with the 17-kDa-specific monoclonal antibody. The rev gene product was found to be expressed in low-passage, but not in high-passage, B. burgdorferi B31. Correspondingly, the rev gene was not present in strain B31 genomic DNA from cultures that had been passaged >50 times. Serum samples from Lyme disease patients demonstrated an antibody response against the Rev protein. The generation of an anti-Rev response in Lyme disease patients, and in mice by tick bite inoculation, provides evidence that the Rev protein is expressed and immunogenic during the course of natural transmission and infection.     

Effect of phenytoin on smoke inhalation injury in sheep

To determine whether the anti-inflammatory effects of phenytoin might reduce cardiopulmonary dysfunction we studied the effects of phenytoin treatment on acute lung injury induced by smoke inhalation. Twenty-one chronically instrumented sheep were observed for 24 h after smoke inhalation injury. Myocardial contractility was evaluated by left ventricular end-systolic pressure-diameter relationship (LVESPDR) with a pair of ultrasonic transducers and strain-gauge transducer. In the control group (n = 6), uninjured sheep were given a bolus of phenytoin (12.5 mg/kg). Smoke-insufflated sheep were divided into nontreatment (n = 7) and phenytoin (n = 8) groups. Phenytoin alone had no effects in uninjured sheep except an early rise in heart rate and LVESPDR. In the group given smoke without treatment, there was a significant increase in pulmonary artery pressure and pulmonary vascular resistance index and a decrease in cardiac index. Pulmonary vascular changes were attenuated by treatment with phenytoin. Pulmonary transvascular fluid flux was evaluated by using a lung lymph fistula. LVESPDR fell in the smoke group but not in the group given phenytoin. There was a marked increase in lung lymph flow with smoke inhalation but this phenomenon was not affected by phenytoin treatment. In conclusion, phenytoin treatment reduced early hemodynamic depression.     

Pulmonary cystic keratinizing squamous cell lesions of rats after inhalation/instillation of different particles

Cystic keratinizing squamous cell lesions from three inhalation studies (Study A, B, C) and one intratracheal instillation study (Study D) in rats were reclassified and a certain number of lesions examined immunohistochemically for PCNA (proliferating cell nuclear antigen) as a marker of cellular proliferation. The following classification was used: squamous cell metaplasia with marked keratinization, keratinizing cyst, cystic keratinizing epithelioma, cystic keratinizing squamous cell carcinoma, keratinizing squamous cell carcinoma and non-keratinizing squamous cell carcinoma. In study A (inhalation of coal oven exhaust and subcutaneous injection of a high dose of DB (ah)A) 49.3% of rats developed cystic keratinizing squamous cell carcinomas. Inhalation of coal oven exhaust gas together with intratracheal instillation of crocidolite or subcutaneous injection of a low dose DB(ah)A (dibenz(ah)anthracene) resulted in cystic keratinizing squamous cell carcinomas in 23% to 24% of the rats. High incidences of cystic squamous cell carcinomas in the range of 31.9% to 76.4% were observed in rats of Study B1 after a 10-months exposure to tar/pitch condensation aerosol (different B(a)P (benzo(a)pyrene) concentrations) with added carbon black in some groups. After a 20-months exposure period to the same inhalation atmospheres (Study B2) the incidence of squamous cell carcinomas was increased up to 95.8%. Exposure of rats to various concentrations of unfiltered diesel exhaust (Study C) resulted in incidences of cystic keratinizing epitheliomas ranging from 2.5% (2.5 mg/m3) to 10.7% (7.5 mg/m3). Epitheliomas were also observed in 16.2% of carbon black and 16.0% of titanium dioxide exposed rats. Only a few cystic keratinizing squamous cell carcinomas occurred. In the intratrachel instillation study (Study D) increased incidences of cystic keratinizing epitheliomas occurred in rats exposed to native diesel exhaust particles (16.7%), high dose of extracted diesel exhaust particles (14.6%), extracted printex 90-carbon black particles (18.8%), and extracted printex 90-carbon black particles + B(a)P (18.8%). High indicences of cystic keratinizing squamous cell carcinomas were noted in rats that received 15 mg B(a)P (14.6%) or 30 mg B(a)P (72.7%) intratracheally. Immunohistochemical labeling of nuclei with PCNA demonstrated proliferative activity in one or two (and focally more than two) peripheral cell layers of cystic keratinizing epitheliomas and in more than three peripheral cell layers of cystic keratinizing squamous cell carcinomas and keratinizing squamous cell carcinomas. The wall of keratinizing cysts showed no or a weak reaction.     

Relationship of burn-induced lung lipid peroxidation on the degree of injury after smoke inhalation and a body burn

OBJECTIVE: We compared the effect of a modest smoke inhalation injury, a burn injury alone, and a smoke inhalation injury plus a body burn, on the degree of lung oxidant-induced lipid peroxidation and lung injury. DESIGN: Prospective animal study with concurrent controls. SETTING: An animal laboratory. SUBJECTS: Forty-four adult yearling female sheep (weight range 45 to 50 kg). INTERVENTIONS: Forty-four sheep were prepared with lung and prefemoral (soft tissue) lymph fistulas. Twelve breaths of cooled smoke with tidal volume of 10 mL/kg body weight were given to 24 sheep, producing a peak blood carboxyhemoglobin of 25% to 30%. Twelve sheep also received a 15% total body surface third-degree burn. Sheep were killed at 4 or 24 hrs. MEASUREMENTS AND MAIN RESULTS: Circulating lipid peroxidation was monitored as conjugated dienes and tracheobronchial mucosal and lung parenchyma as malondialdehyde. Antioxidant defenses were monitored by catalase activity. Lung physiologic and histologic changes were compared. We noted intense airways inflammation in both smoke inhalation groups and lung parenchymal inflammation in all groups. Lung lymph flow was modestly increased (two-fold) in the smoke inhalation groups. Alveolar water content was not significantly increased after any injury. PaO2 was decreased at 24 hrs after the smoke insult alone. Parenchymal malondialdehyde content did not increase with the smoke insult alone, but did increase from a control value of 110 +/- 20 to 270 +/- 24 nmol/g tissue by 4 hrs in the combined burn and smoke injury group, while catalase activity decreased. Airway mucosal malondialdehyde did not increase in any group. CONCLUSIONS: We conclude that alveolar capillary permeability is not increased early after a moderate smoke injury or smoke injury with burn. Lipid peroxidation is not increased in large airway or lung parenchyma with early after-smoke exposure. The addition of a burn significantly increases lung parenchymal lipid peroxidation, but the oxidant changes do not correspond with the degree of early lung dysfunction.     

Are smokers' self-reports of inhalation a useful measure of smoke exposure

The relation between self-assessed and objective measures of inhalation was studied in 75 smokers who assigned themselves to one of four inhalation categories, and also estimated inhalation using a rating scale. The analysis of presmoking carbon monoxide concentration in expired air, and of the rise in carbon monoxide concentration over smoking, provided an objective measure of inhalation. These was a weak but significant correlation between self-rated inhalation and rise in carbon monoxide, but no correlation with the longer-term exposure measured by presmoking levels of carbon monoxide. Differences in exposure to carbon monoxide according to self-assessed inhalation category were non-significant. It is concluded that neither subjective measure of inhalation contributes usefully to the estimation of smoke exposure among smokers who inhale.     

Coagulation studies and platelet function after somatostatin infusion

The effect of short- and long-term somatostatin (GIF) administration on haemostatic function in man was investigated. The dosage programme applied in this study was 250 mug GIF as a bolus injection and 250 mug GIF/h by way of infusion. In five healthy volunteers a short-term (3h) treatment resulted in a statistically significant drop of platelet count and impairment of platelet aggregation at the end of infusion. However, these changes were within the physiologically normal range and disappeared after two hours on all subjects. Other parameters such as bleeding time, thromboplastin and partial thromboplastin time, fibrinogen, fibrin/fibrinogen split products, plasma factor XIII, ethanol gelation test were not affected. In two patients with gastric haemorrhage and persistent amylasaemia a 67 or 120-h treatment induced no remarkable haemostatic defect. By contrast, peptic ulcer bleeding in one patient stopped 60 min after starting the GIF infusion. These studies indicated that somatostatin administration in man at the dosage programme used neither results in clinical evidence indicating bleeding tendency nor does it influence laboratory parameters in an apparent way.     

Pulmonary function changes after nebulised and intravenous frusemide in ventilated premature infants

AIMS: To compare the effects of a single dose of frusemide administered either intravenously or by nebulisation on pulmonary mechanics in premature infants with evolving chronic lung disease. METHODS: The effect of frusemide on pulmonary mechanics was studied at a median postnatal age of 23 (range 14-52) days in 19 premature infants at 24 to 30 weeks gestational age, who had been dependent on mechanical ventilation since birth. Frusemide (1 mg/kg/body weight) was administered, in random order, intravenously and by nebulisation, on two separate occasions 24 hours apart. Pulmonary function studies were performed before and at 30, 60, and 120 minutes after administration of frusemide. Urine was collected for six hours immediately before and for six hours after administration of frusemide. RESULTS: Nebulised frusemide increased the tidal volume 31 (SE 11.5)% and compliance 34 (SE 12)% after two hours, whereas no change in either was noted for up to two hours after intravenous frusemide administration. Neither intravenous nor nebulised frusemide had any effect on airway resistance. Six hour urine output increased from a mean (SE) of 3.3 (0.4) ml/kg/hour to 5.9 (0.8) ml/kg/hour following intravenous frusemide administration while nebulised frusemide had no effect on urine output. Urinary sodium, potassium, and chloride losses were also significantly higher after intravenous frusemide, whereas nebulised frusemide did not increase urinary electrolyte losses. CONCLUSION: Single dose nebulised frusemide improves pulmonary function in premature infants with evolving chronic lung disease without adverse effects on fluid and electrolyte balance.     

Pulmonary complications and respiratory function changes after bone marrow transplantation in children

We prospectively assessed the frequency of pulmonary complications and the natural course of lung function after bone marrow transplantation (BMT), as well as the effect of several risk factors in a homogeneous group of 39 children who underwent allogeneic or autologous BMT for haematological malignancies between 1992 and 1995. Four patients developed pneumonia within the first 3 months and three 3-6 months after BMT. A considerable percentage of acute bronchitis was recorded throughout the follow-up. Three patients died after the 6 month visit because of pneumonia (two patients) and pulmonary aspergillosis (one patient). No patients had obstructive lung disease syndrome. At 3 months after BMT, forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and transfer factor of the lung for carbon monoxide (TL,CO) significantly decreased, but FEV1/FVC ratio and maximal expiratory flow at 25% of FVC remained unchanged, suggesting a restrictive defect with diffusion impairment. At 18 months, there was a progressive recovery in lung function, although only 11 patients had normalized. Seropositivity for cytomegalovirus had a significant effect on lung function whereas graft-versus-host disease also had an effect, although it was not statistically significant. Baseline respiratory function, type of transplant, type of conditioning regimen and respiratory infections did not significantly affect the outcome of BMT. The high frequency of severe lung function abnormalities found in this study, suggests a careful functional monitoring in all subjects undergoing bone marrow transplantation, even in the absence of respiratory symptoms.     

Pulmonary vascular responses to inhalation anaesthesia in isolated dog lungs

To study the mechanisms of action of four inhalation anaesthetics (diethyl ether, halothane, methoxyflurane, and nitrogen monoxide) upon the pulmonary circulation, the authors carried out 45 experiments in isolated, perfused and ventilated canine lungs. The effects of the anaesthetics were studied at 1) normotonic perfusion, 2) enhanced pulmonary blood flow, 3) microembolism-induced pulmonary hypertension. In the first two-experimental series, no effects of the test anaesthetics on the pulmonary vascular responses became manifest; at microembolism-induced pulmonary hypertension, halothane lowered the pulmonary vascular resistance, whereas diethyl ether stabilized the elevated vascular tone. Methoxyflurane and nitrogen monoxide had no marked effects on the pulmonary vascular responses. On the basis of their experiences and of data published in the literature the authors conclude that there exist regional mechanisms of action of anaesthetics on the lung vessels, activated by the release or action of mediators.     

Leukoencephalopathy after inhalation of heroin vapor

A 25-year-old man presented in March 1996 with progressive dysarthria, cerebellar ataxia, and dystonia, which began after he inhaled heroin vapor for a full day 2 months previously. The patient had a 2-year history of heroin inhalation. Magnetic brain stimulation showed waveform dysynchronization suggestive of motor pathway perturbation above the cervical spinal level. Brain computed tomography and magnetic resonance imaging revealed extensive symmetric white matter involvement of bilateral cerebral and cerebellar hemispheres and the brainstem, especially along the corticospinal tract. The clinical features, electrophysiologic manifestations, and imaging studies strongly indicated a lipophilic toxin-induced demyelinating process, mainly involving the central motor system, as the most likely cause of heroin leukoencephalopathy. This is the first reported case of heroin-related leukoencephalopathy in Taiwan.     

Sevoflurane inhalation reduced bronchospasm after extubation

A 73-year-old female was scheduled for left upper lobectomy. She had no history of asthma or chronic obstructive pulmonary disease. During the operation, respiratory sound was clear. As spontaneous breathing was regular and stable after the reversal of neuromuscular blockade, an endotracheal tube was extubated. But soon after the extubation, wheezing and gasping respiration occurred and she complained of dyspnea. Therefore, we administered aminophylline and steroid intravenously, and the patient's lungs were ventilated manually with 100% oxygen. But after 10 minutes, there was no improvement in symptoms, and sevoflurane inhalation was started immediately. Inspiratory sevoflurane concentration was 4% at first, and was decreased to 2%. About 20 minutes after starting sevoflurane inhalation, wheezing was reduced. Sevoflurane may be useful in the treatment of bronchospasm after extubation.     

Pulmonary hypertension after transjugular intrahepatic portosystemic shunt: effects on right ventricular function

The short- and mid-term hemodynamic effects of transjugular intrahepatic portosystemic shunt (TIPS) were studied in 16 sedated cirrhotic patients. Indications included relapsing variceal bleeding (n = 10) and refractory ascites (n = 6). The decrease of porto-atrial pressure gradient (from 20.4 +/- 4.2 mm Hg to 10.1 +/- 2.4 mmHg; P < .05) was associated with an increase of mean pulmonary artery pressure (MPAP) (from 12.3 +/- 3.0 mm Hg to 20.3 +/- 5.3 mm Hg; P < .05) and of right atrial pressure (RAP) from 3.4 +/- 2.6 mm Hg to 8.3 +/- 3.7 mm Hg; P < .05), whereas right ventricular end-diastolic volume (RVEDVI) remained unchanged. The significant increase of cardiac index (CI) (from 4.5 +/- 1.2 L/min/m2 to 5.0 +/- 1.1 L/min/m2; P < .05) was essentially attributable to an increase of heart rate (HR) (from 81 +/- 11 to 88 +/- 10 beats/min; P < .05). Systemic vascular resistance (SVR) decreased (from 812 +/- 281 to 666 +/- 191 dynes/sec/cm5; P < .05), whereas pulmonary vascular resistance (PVR) increased (from 60.6 +/- 29.6 to 82.0 +/- 34.6 dynes/sec/cm5; P < .05). After transient shunt occlusion with a balloon catheter, all of the hemodynamic parameters returned to baseline values, except pulmonary artery pressure, which also decreased but remained significantly increased. One month after TIPS, pulmonary pressure remained elevated, and CI further increased. It is concluded that increased PVR is the major hemodynamic alteration occurring after TIPS placement. It correlates with the decrease of porto-atrial gradient and is probably mediated by both mechanical and neurohumoral factors.     

Pulmonary function after one-lung ventilation in newborns: the basis for neonatal thoracoscopy

BACKGROUND: To maintain good exposure during major video-assisted thoracic surgery it is necessary to deflate completely the ipsilateral lung. However, little is known about the effects of one-lung ventilation (OLV) on pulmonary function in newborn patients. METHODS: Ten neonatal domestic pigs with a mean age of 6+/-0.6 days were intubated and ventilated in pressure-controlled mode (inspired oxygen fraction=1.0). One-lung ventilation was maintained for 120 minutes. Serial measurements of hemodynamics and gas exchange were done before, during, and until 90 minutes after OLV. Pulmonary function testing was performed before and after OLV for each lung separately. RESULTS: With the inspired oxygen fraction set at 1.0, arterial oxygen saturation remained stable at 100% during OLV. Venous admixture and alveolar-arterial oxygen tension gradient increased slightly from the baseline value of 2.6% +/-0.3% to 3.8%+/-0.3% during OLV (mean+/-standard error of the mean; p=0.02), and from 358+/-28 to 407+/-18 mm Hg (not significant), respectively. Both values returned to baseline during the subsequent ventilation of both lungs. Static compliance and resistance of the ventilated lung did not change. Compliance of the collapsed lung decreased after reexpansion from 0.42+/-0.07 to 0.29+/-0.06 mL x cm H2O(-1) x kg(-1), p=0.008). Resistance remained unchanged (0.22+/-0.02 versus 0.25+/-0.05 cm H2O x L(-1) x s(-1); not significant). CONCLUSIONS: There were only minor effects on pulmonary function during and after OLV in the neonatal piglet. Alterations in gas exchange during OLV were minimal. Prolonged collapse of the lung with subsequent reexpansion was associated with a slight decrease in compliance, indicating some mild lung injury.     

Pulmonary host defense responses to inhalation of sulfuric acid and ozone

The effects of simultaneous exposure to ozone (O3) and sulfuric acid [H2SO4, 0.23 microns volume median diameter (VMD)] and a single exposure to ultrafine (less than 0.1 micron VMD) H2SO4 under various conditions were studied using the infectivity/mortality and the ciliary beating frequency model systems. A 3-h exposure to a combined aerosol of 196 micrograms O3/m3 and 483 or 241 micrograms H2SO4/m3 significantly increased the susceptibility of mice to a laboratory-induced respiratory infection. However, exposure to 543 micrograms ultrafine H2SO4/m3 for 2 h or 365 micrograms/m3 2 h/d for 5 d did not significantly affect this parameter. Upper airway response, as measured by changes in hamster tracheal ciliary beating frequency, was not affected by either a 3-h combined exposure to 196 micrograms O3/m3 and 847 micrograms H2SO4/m3 or a 2-h exposure to 458 micrograms ultrafine H2SO4/m3.