Bisphosphonates therapy for osteoarthritis: a meta-analysis of randomized controlled trials

High-turnover type bone metabolism derangement has been considered to be one of the major causes of osteoarthritis (OA). Bisphosphonates can attach to hydroxyapatite binding sites on bony surfaces, particularly those which are undergoing active bone resorption. To evaluate the effectiveness of bisphosphonates in OA treatment, literature databases were searched from inception to February 28, 2016 for clinical studies of bisphosphonates for OA treatment. All randomized controlled trials in which bisphosphonates therapy was compared with a placebo or a conventional medication, were selected. 15/1145 studies were eligible for analysis, which included 3566 participants. Bisphosphonates therapy improved pain, stiffness and function significantly in OA assessed by the Western Ontario and McMaster Universities Arthritis Index scale (MD = 4.59; 95 % CI 2.83-6.34; P < 0.00001; MD = 1.43; 95 % CI 0.83-2.23; P = 0.0005; MD = 2.01; 95 % CI 1.27-2.75; P < 0.00001). Bisphosphonates also reduced osteophyte score significantly (MD = -0.51; 95 % CI -0.84 to -0.19; P = 0.002). However, no significant differences were found in subjective improvement, osteoarthritis progression, the number of required acetaminophen treatment or joint replacement. In conclusion, bisphosphonates therapy is effective in relieving pain,stiffness and accelerating functional recovery in OA. Limitations of the studies we analysed included the differences in duration of bisphosphonates use, the doses and types of bisphosphonates and the lack of long-term data on OA joint structure modification after bisphosphonates therapy. More targeted studies are required to evaluate on the effectiveness of bisphosphonates for OA treatment.

Mesenchymal stem cells ameliorate tissue damages triggered by renal ischemia and reperfusion injury

BACKGROUND

Ischemia and reperfusion injury (I/R) is the major cause of acute renal failure (ARF) with high mortality rates. Because alternative therapies are needed, we investigated the use of stem cell therapy to modulate inflammation in a renal I/R model.

METHODS

To study kidney I/R injury, we clamped bilateral pedicles for 60 minutes. Mesenchymal stem cells (MSC), which had been isolated and cultivated in plastic flasks, were administered to mice 6 hours after injury. Real-time polymerase chain reaction was used to quantify interleukin (IL)-4 and IL-1beta mRNAs. Proliferative nuclear cell antigen (PCNA) was used to calculate tubular regeneration.

RESULTS

Administration of MSC attenuated renal injury; serum creatinine and plasma urea levels were significantly reduced 24 hours after reperfusion. PCNA immunohistochemistry showed that regeneration occurred faster in renal tissues of animals that received MSC than in tissues of control animals. Analyses of cytokine expression in renal tissue demonstrated a greater level of anti-inflammatory cytokines in MSC-treated animals.

CONCLUSION

These results showed an antiinflammatory pattern in MSC-treated animals, demonstrating the potential of MSC to modulate I/R, leading to earlier regeneration of damaged renal tissue.

Vascular regulation of type II cell exocytosis

To determine whether lung capillary pressure regulates surfactant secretion, we viewed alveoli of the constantly inflated, isolated blood-perfused rat lung by fluorescence microscopy. By alveolar micropuncture we infused fura 2 and lamellar body (LB)-localizing dyes for fluorescence detection of, respectively, the alveolar cytosolic Ca(2+) concentration ([Ca(2+)](i)) and type II cell exocytosis. Increasing left atrial pressure (Pla) from 5 to 10 cmH(2)O increased septal capillary diameter by 26% and induced marked alveolar [Ca(2+)](i) oscillations that abated on relief of pressure elevation. The rate of loss of LB fluorescence that reflects the LB exocytosis rate increased fourfold after the pressure elevation and continued at the same rate even after pressure and [Ca(2+)](i) oscillations had returned to baseline. In alveoli pretreated with either 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, the intracellular Ca(2+) chelator, or heptanol, the gap junctional blocker, the pressure-induced exocytosis was completely inhibited. We conclude that capillary pressure and surfactant secretion are mechanically coupled. The secretion initiates in a Ca(2+)-dependent manner but is sustained by Ca(2+)-independent mechanisms.

Rapid alveolar liquid removal by a novel convective mechanism

Although alveoli clear liquid by active transport, the presence of surface-active material on the alveolar surface suggests that convective mechanisms for rapid liquid removal may exist. To determine such mechanisms, we held the isolated blood-perfused rat lung at a constant alveolar pressure (PA). Under videomicroscopy, we micropunctured a single alveolus to infuse saline or Ringer solution in approximately 10 adjacent alveoli. Infused alveoli were lost from view. However, as the infused liquid cleared, the alveoli reappeared and their diameters could be quantified. Hence the time-dependent determination of alveolar diameter provided a means for quantifying the time to complete liquid removal (C(t)) in single alveoli. All determinations were obtained at an PA of 5 cmH(2)O. C(t), which related inversely to alveolar diameter, averaged 4.5 s in alveoli with the fastest liquid removal. Injections of dye-stained liquid revealed that the liquid flowed from the injected alveoli to adjacent air-filled alveoli. Lung hyperinflations instituted by cycling PA between 5 and 15 cmH(2)O decreased C(t) by 50%. Chelation of intracellular Ca(2+) prolonged C(t) and abolished the inflation-induced enhancement of liquid removal. We conclude that when liquid is injected in a few alveoli, it rapidly flows to adjacent air-filled alveoli. The removal mechanisms are dependent on alveolar size, inflation, and intracellular Ca(2+). We speculate that removal of liquid from the alveolar surface is determined by the curvature and surface-active properties of the air-liquid interface.

Suspended rice particles for cultivation of Monascus purpureus in a tower-type bioreactor

Cultivation of Monascus purpureus (CCRC 31615) for the production of natural pigments was investigated. Traditionally, Monascus species were grown on rice by solid-state culture. For large-scale cultivation, solid-state cultures were associated with some problems such as contamination and scale-up. By using submerged cultures with rice particles, a stirred-tank fermentor was not suitable for submerged cultures as the impeller tended to break the particles into small pieces. A conventional bubble column was also unsuitable as its mixing capability was poor. In the present study, a modified bubble column with wire-mesh draft tubes was employed for the cultivation of M. purpureus. The proposed column had a shorter mixing time and a higher oxygen transfer rate relative to the conventional bubble column. The production of pigments using the proposed column was up to 80% higher than that achieved using the conventional bubble column.

Pleural tissue hyaluronan produced by postmortem ventilation in rabbits

We developed a method that used Alcian blue bound to hyaluronan to measure pleural hyaluronan in rabbits postmortem. Rabbits were killed, then ventilated with 21% O2--5% CO2--74% N2 for 3 h. The pleural liquid was removed by suction and 5 ml Alcian blue stock solution (0.33 mg/ml, 3.3 pH) was injected into each chest cavity. After 10 min, the Alcian blue solution was removed and the unbound Alcian blue solution (supernatant) separated by centrifugation and filtration. The supernatant transmissibility (T) was measured spectrophotometrically at 613 nm. Supernatant Alcian blue concentration (Cab) was obtained from a calibration curve of T versus dilutions of stock solution Cab. Alcian blue bound to pleural tissue hyaluronan was obtained by subtracting supernatant Cab from stock solution Cab. Pleural tissue hyaluronan was obtained from a calibration curve of hyaluronan versus Alcian blue bound to hyaluronan. Compared with control rabbits, pleural tissue hyaluronan (0.21 +/- 0.04 mg/kg) increased twofold, whereas pleural liquid volume decreased by 30% after 3 h of ventilation. Pleural effusions present 3 h postmortem without ventilation did not change pleural tissue hyaluronan from control values. Thus ventilation-induced pleural liquid shear stress, not increased filtration, was the stimulus for the increased hyaluronan produced from pleural mesothelial cells.

A novel signaling mechanism between gas and blood compartments of the lung

Propagation of inflammatory signals from the airspace to the vascular space is pivotal in lung inflammation, but mechanisms of intercompartmental signaling are not understood. To define signaling mechanisms, we microinfused single alveoli of blood-perfused rat lung with TNF-alpha, and determined in situ cytosolic Ca(2+) concentration ([Ca(2+)](i)) by the fura-2 ratio method, cytosolic phospholipase A(2) (cPLA(2)) activation and P-selectin expression by indirect immunofluorescence. Alveolar TNF-alpha increased [Ca(2+)](i) and activated cPLA(2) in alveolar epithelial cells, and increased both endothelial [Ca(2+)](i) and P-selectin expression in adjoining perialveolar capillaries. All responses were blocked by pretreating alveoli with a mAb against TNF receptor 1 (TNFR1). Crosslinking alveolar TNFR1 also increased endothelial [Ca(2+)](i). However, the endothelial responses to alveolar TNF-alpha were blocked by alveolar preinjection of the intracellular Ca(2+) chelator BAPTA-AM, or the cPLA(2) blockers AACOCF(3) and MAFP. The gap-junction uncoupler heptanol had no effect. We conclude that TNF-alpha induces signaling between the alveolar and vascular compartments of the lung. The signaling is attributable to ligation of alveolar TNFR1 followed by receptor-mediated [Ca(2+)](i) increases and cPLA(2) activation in alveolar epithelium. These novel mechanisms may be relevant in the alveolar recruitment of leukocytes.

Regional pleural filtration and absorption measured by fluorescent tracers in rabbits

In prone anesthetized rabbits, we used Evans blue-dyed albumin (EBA) to study regional pleural filtration and FITC dextran to study regional pleural absorption. Evans blue was injected intravenously, and the animals were ventilated for 6 h at either of two levels of ventilation. Postmortem the right rib cage was frozen and thawed before study. EBA fluorescence emitted from the rib cage surface was measured along the cranial-caudal axis near the mid chest with fluorescence videomicroscopy. Fluorescent light intensity increased from the third to the eighth rib in a cyclic fashion, with peaks at the ribs and troughs at the intercostal spaces. This increase was greater at the higher ventilation. Fluorescent images of cross sections of a frozen rib cage verified a cranial-caudal gradient in filtration. Fluorescent images of FITC dextran absorbed from the pleural space into the rib cage surface indicated major areas of absorption at the ventral, caudal, and cranial regions adjacent to the lung margins and areas of absorption scattered in the intercostal spaces. Simultaneous measurements of EBA filtration and FITC absorption showed sites of maximal filtration that were different from sites of maximal absorption. Pleural uptake of fluorescent microspheres (2-microm diameter) located lymphatic stomata distributed randomly within clusters in the intercostal spaces and channels of lymphatic lacunae parallel to blood vessels. Diaphragmatic uptake of microspheres was confined mainly to the ventral surface of the central tendon. Visceral pleural absorption was minimal.

Effects of ventilation on hyaluronan and protein concentration in pleural liquid of anesthetized and conscious rabbits

The hypothesis of this study is that pleural lubrication is enhanced by hyaluronan acting as a boundary lubricant in pleural liquid and by pleural filtration as reflected in changes in protein concentration with ventilation. Anesthetized rabbits were injected intravenously with Evans blue dye and ventilated with 100% O2 at either of two levels of ventilation for 6 h. Postmortem values of hyaluronan, total protein, and Evans blue-dyed albumin (EBA) concentrations in pleural liquid were greater at the higher ventilation, consistent with increases in boundary lubrication, pleural membrane permeability, and pleural filtration. To determine whether these effects were caused by hyperoxia or anesthesia, conscious rabbits were ventilated with either 3% CO2 or room air in a box for 6, 12, or 24 h. Similar to the anesthetized rabbits, pleural liquid hyaluronan concentration after 24 h was higher in the conscious rabbits with the hypercapnic-induced greater ventilation. By contrast, the time course of total protein and EBA in pleural liquid was similar in both groups of conscious rabbits, indicating no effect of ventilation on pleural permeability. The increase in pleural liquid hyaluronan concentration might be the result of mesothelial cell stimulation by a ventilation-induced increase in pleural liquid shear stress.

Effect of mechanical ventilation on regional variation of pleural liquid thickness in rabbits

We studied the effect of ventilation on the regional distribution of pleural liquid thickness in anesthetized rabbits. Three transparent pleural windows were made between the second and eight intercostal space along the midaxillary line of the right chest. Fluorescein isothiocyanate-labeled dextran (1 ml) was injected into the pleural space through a rib capsule and allowed to mix with the pleural liquid. The light emitted from the pleural space beneath the windows was measured by fluorescence videomicroscopy at a constant tidal volume (20 ml) and two ventilation frequencies (20 and 40 breaths/min). Pleural liquid thickness was determined from the light measurements after in vitro calibration of pleural liquid collected postmortem. At 20 breaths/min, pleural liquid thickness increased with a cranial-caudal distance from 5 microns at the second to third intercostal space to 30 microns at the sixth through eighth intercostal space. At 40 breaths/min, pleural space thickness was unchanged at the second to third intercostal space but increased to 46 microns at the sixth through eighth intercostal space. To determine this effect on pleural liquid shear stress, we measured relative lung velocity from videomicroscopic images of the lung surface through the windows. Lung velocity amplitude increased with cranial-caudal distance and with ventilation frequency. Calculated shear stress amplitude was constant with cranial-caudal distance but increased with ventilation frequency. Thus, pleural liquid thickness is matched to the relative lung motion so as to maintain a spatially uniform shear stress amplitude in pleural liquid during mechanical ventilation.

Effect of blood flow on capillary transit time and oxygenation in excised rabbit lung

We used an isolated perfused lung preparation of the rabbit to study the effect of increasing blood flow on pulmonary capillary transit time by two methods. In one method, capillary transit time was measured from fluorescent dye dilution curves from arterioles and venules of the subpleural microcirculation. Values of transit time were similar to those for the whole lung determined by dividing capillary blood volume by blood flow. Capillary transit times averaged 0.50-0.62 sec at a control blood flow of 80 ml min-1 kg-1 and decreased to 0.14-0.18 sec as blood flow increased to 6 times control. To determine whether the reduced transit time would limit O2 transport, we studied the effect of blood flow on oxygenation. Two isolated rabbit lungs were perfused in series. Blood from one lung deoxygenated by ventilation with a N2-CO2 mixture was oxygenated by the test lung ventilated with air. Ventilation was matched to blood flow. PO2 and PCO2 were measured in blood flowing into and out of the test lung. At all flows, no significant alveolar gas-to-end-capillary blood PO2 gradient (A-aDO2) was measured. The isolated perfused rabbit lung showed no transit time limitation to oxygenation for blood flows that are consistent with heavy exercise in vivo.

Chromosome aberrations induced in human lymphocytes after partial-body irradiation

Chromosomal aberrations in peripheral blood lymphocytes obtained from two patients before and after they received one fraction of partial-body irradiation for palliative treatment were analyzed. Blood samples were taken 30 min and 24 h after radiation treatment. The yield of dicentrics obtained from case A 30 min after a partial-body (about 21%) treatment with 8 Gy was 0.066/cell, while the yield obtained 24 h after radiation treatment was 0.071/cell. The fraction of irradiated lymphocytes that reached metaphase at 52 h was 0.08 as evaluated by mixing cultures of in vitro irradiated and unirradiated blood. The yield of dicentrics for blood from case B 30 min after 6 Gy partial-body (about 24%) irradiation was 0.655/cell, while the yield 24 h after irradiation was 0.605/cell. The fraction of irradiated cells was 0.29. Estimation of doses and irradiated fractions for the two cases using the method proposed by Dolphin and the Qdr method is discussed. Although there was no significant difference between the mean yields of dicentrics per cell obtained 30 min and 24 h after radiation treatment, the data obtained at 24 h seemed more useful for the purpose of dose estimation. When a higher dose (8 Gy) was delivered to a smaller percentage of the body, underestimation of the dose was encountered.

Arterial, capillary, and venous transit times and dispersion measured in isolated rabbit lungs

Transit time and relative dispersion of the arterial, capillary, and venous segments of the pulmonary circulation were measured in isolated perfused rabbit lungs. Fluorescence videomicroscopy was used to record the passage of dye through the main pulmonary artery, subpleural microcirculation, and venous outflow. Dye dilution curves were obtained at the main pulmonary artery, subpleural arterioles and venules, and pulmonary vein. Measurements were made at 5-cmH2O airway pressure, at blood flows of approximately 80, 50, and 25 ml.min-1.kg-1, and at left atrial pressures of approximately 0 cmH2O (zone 2) and approximately 12 cmH2O (zone 3). The dye dilution curves were modeled as lagged normal density curves that were used to calculate transit time and relative dispersion between the pulmonary artery and arteriole (artery), arteriole and venule (capillary), venule and pulmonary vein (vein), and pulmonary artery and pulmonary vein (whole lung). In open-chest anesthetized dogs, the passage of dye was recorded from the subpleural arterioles and venules between the seventh and eighth ribs in the left lateral position. At comparable blood flows, capillary transit time was larger in the dog than in the rabbit lung [3.4 +/- 2.4 (SD) vs. 0.87 +/- 0.47 s]. In the rabbit lung, relative dispersion was greater in pulmonary capillaries (average values 0.83-1.6) and veins (0.91-1.6) than in arteries (0.39-0.50), which was similar to the whole lung dispersion (0.47-0.52). A similarly high dispersion (0.93) was measured in the dog's pulmonary capillaries. Thus high dispersion in pulmonary capillaries and veins cannot be detected by whole lung dispersion measurements.

Model for a pump that drives circulation of pleural fluid

Physical and mathematical models were used to study a mechanism that could maintain the layer of pleural fluid that covers the surface of the lung. The pleural space was modeled as a thin layer of viscous fluid lying between a membrane carrying tension (T), representing the lung, and a rigid wall, representing the chest wall. Flow of the fluid was driven by sliding between the membrane and wall. The physical model consisted of a cylindrical balloon with strings stretched along its surface. When the balloon was inflated inside a vertical circular cylinder containing a viscous fluid, the strings formed narrow vertical channels between broad regions in which the balloon pressed against the outer cylinder. The channels simulated the pleural space in the regions of lobar margins. Oscillatory rotation of the outer cylinder maintained a lubricating layer of fluid between the balloon and the cylinder. The thickness of the fluid layer (h), measured by fluorescence videomicroscopy, was larger for larger fluid viscosity (mu), larger sliding velocity (U), and smaller pressure difference (delta P) between the layer and the channel. A mathematical model of the flow in a horizontal section was analyzed, and numerical solutions were obtained for parameter values of mu, U, delta P, and T that matched those of the physical model. The computed results agreed reasonably well with the experimental results. Scaling laws yield the prediction that h is approximately (T/delta P)(microU/T)2/3. For physiological values of the parameters, the predicted value of h is approximately 10(-3) cm, in good agreement with the observed thickness of the pleural space.

Effect of ventilation frequency and tidal volume on pleural space thickness in rabbits

The thickness of the pleural space was measured by fluorescence video-microscopy during mechanical ventilation in anesthetized paralyzed rabbits. A transparent parietal pleural window was made in the fourth or sixth intercostal space near midchest by dissection of intercostal muscle and endothoracic fascia. Fluorescence-labeled (fluorescein isothiocyanate) dextran solution (1 ml) was injected into the pleural space via a rib capsule and allowed to mix with the pleural liquid. With the rabbit in the left lateral decubitus position and the pleural window superior, the light emitted from the pleural liquid through the pleural window was measured through the videomicroscope. Both ventilation frequency and tidal volume were varied. Pleural space thickness was determined by in vitro calibration of the pleural liquid at the end of the experiment. At a frequency of 40 breaths/min and a tidal volume of 20 ml, pleural space thickness averaged 35 +/- 15 (SD) microns (n = 7). When frequency was reduced to 8 breaths/min, this value was reduced by 40% to 22 +/- 11 microns. A reduction in tidal volume from 20 to 6 ml at a frequency of 40 breaths/min produced a similar reduction in pleural space thickness. During apnea, pleural space thickness averaged 11 +/- 3 microns. Cardiogenic motion had no measurable effect on pleural space thickness. The increased pleural space thickness with ventilation might serve to reduce the power dissipated due to sliding of the lung relative to the chest wall. Results support the concept of lubrication as the primary function of the pleural space.

Upward flow of pleural liquid near lobar margins due to cardiogenic motion

In anesthetized, paralyzed, supine rabbits (3-4 kg) during apnea, we injected fluorescent dye or fluorescent microspheres (2 or 6 microns diam) into the dependent pleural space and observed the arrival and movement of the dye or microspheres at superior regions. Injection was through a rib capsule located in the dependent right chest. The dye or microspheres were observed through a pleural window overlying a lobar margin. The vertical distance between the capsule and window was 3-4 cm. The movement of the dye or microspheres was recorded via a fluorescence videomicroscope, and the signals were analyzed for dye transit time and microsphere velocity. The transit time of the dye to traverse the height of the pleural space was calculated from the light intensity vs. time curve. Transit time during apnea averaged 6.0 +/- 3.4 (SD) min (n = 4). Transit time measured after the onset of mechanical ventilation was < 1 min. The direction and speed of a microsphere moving in the relatively thick pleural space adjacent to the lobar margin depended on its distance from the lobar margin. Microspheres moved upward in the pleural space that was in proximity to the lobar margin but downward at farther distances from the lobar margin. Pleural liquid recirculation occurs via the pleural space adjacent to lobar margins.

Effects of lung inflation and blood flow on capillary transit time in isolated rabbit lungs

In a previous study, direct measurements of pulmonary capillary transit time by fluorescence video microscopy in anesthetized rabbits showed that chest inflation increased capillary transit time and decreased cardiac output. In isolated perfused rabbit lungs we measured the effect of lung volume, left atrial pressure (Pla), and blood flow on capillary transit time. At constant blood flow and constant transpulmonary pressure, a bolus of fluorescent dye was injected into the pulmonary artery and the passage of the dye through the subpleural microcirculation was recorded via the video microscope on videotape. During playback of the video signals, the light emitted from an arteriole and adjacent venule was measured using a video photoanalyzer. Capillary transit time was the difference between the mean time values of the arteriolar and venular dye dilution curves. We measured capillary transit time in three groups of lungs. In group 1, with airway pressure (Paw) at 5 cmH2O, transit time was measured at blood flow of approximately 80, approximately 40, and approximately 20 ml.min-1.kg-1. At each blood flow level, Pla was varied from 0 (Pla less than Paw, zone 2) to 11 cmH2O (Pla greater than Paw, zone 3). In group 2, at constant Paw of 15 cmH2O, Pla was varied from 0 (zone 2) to 22 cmH2O (zone 3) at the same three blood flow levels. In group 3, at each of the three blood flow levels, Paw was varied from 5 to 15 cmH2O while Pla was maintained at 0 cmH2O (zone 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of positive airway pressure on capillary transit time in rabbit lung

We used fluorescence videomicroscopy to measure the passage of fluorescent dye through the subpleural microcirculation of the lung. With the rabbit in the left lateral decubitus position, the subpleural microcirculation was viewed either through a transparent parietal pleural window located in the superior part of the chest or directly with the chest open. There was no physical contact with the chest or lung. The rabbit was anesthetized, paralyzed, and mechanically ventilated with 100% O2. The dye was injected into the right ventricle during a 2-min apneic period to eliminate lung movement due to ventilation. The video signal of the passage of the dye was analyzed frame by frame by use of digital image processing to compensate for cardiogenic oscillations of the lung surface. Gray scale levels of an arteriole and adjacent venule were measured every 1/30 s. Capillary transit time was determined from the difference between the concentration-weighted mean time values of the arteriolar and venular dye dilution curves. We studied the effect of airway pressure (0-20 cmH2O) on transit time. Cardiac output was measured at different airway pressures by the thermal dilution technique. Capillary transit time averaged 0.60 s at functional residual capacity. Right ventricular-to-arteriolar transit time was four times as large as the capillary transit time. An increase in airway pressure from 0-5 to 20 cmH2O resulted in a fourfold increase in both capillary and arterial transit times and a threefold decrease in cardiac output.

Airflow-generated sound in a hollow canine airway cast

We examined the distribution of airflow-generated sound within a flexible model of canine airways. Sounds were picked up by a microphone adapted to a glass conical probe which was introduced through puncture holes in the wall of the model. We acquired 341 measurements in 31 airways between 2.0 and 19.0 mm in diameter at airflow rates from 0 to 2.5 L/s in the inspiratory and expiratory directions. We found that in the expiratory direction, the sound amplitude was approximately linearly related to airway cross-sectional area, with the greatest amplitude occurring in the largest airway. In the inspiratory direction the greatest amplitude occurred in airways of 5 to 8 mm in diameter. At all levels within the model, sound amplitude was approximately linearly related to the square of the airflow. Our findings suggest that in canine airways, the predominant vesicular lung sound-producing locations are the large airways for the expiratory component and the medium-sized airways for the inspiratory component.

Construction of a flexible airway model for teaching

A method of producing flexible and strong models of canine airways is described. The animal's lungs are dried in inflation by using compressed air and then filled with silicone sealer. After this compound dries, the lung tissue is removed by corrosion by using NAOH. The result is a rugged, flexible, and anatomically faithful model of canine airways that is suitable for use in teaching.

The potential oncogenic activity of influenza A virus in lungs of mice

Adult male CD1 mice were inoculated with chicken egg-propagated influenza type A/PR8/34 virus. Fully developed pulmonary pneumonia was found 7 d after the infection. In addition to the pneumatic condition, pronounced thickening of the bronchiolar epithelium denoting hyperplastic and dysplastic transformation of the epithelial cells were also observed. By 11 d of the experiment, extensive papillomatous proliferation of the bronchiolar epithelial cells could be demonstrated. Furthermore, invasive growth of these epithelial cells through the basement membrane and muscularis layer into the alveolar tissues were evident. Such invasive transgression of transformed epithelial cells strongly suggested malignant growth of these cells. Detailed histopathological survey of all the virus-infected lungs revealed tumorous nodule formations in over 80% of the specimens examined. Our present investigation not only confirmed previous claims that cellular transformations (hyperplasia, metaplasia, dysplasia) can be induced with influenza type A virus but also for the first time successfully demonstrated invasive growth and tumorous formation in lungs of infected animals. Our study further reaffirms the oncogenic potential of influenza type A virus.

A morphologic classification and incidence of alveolar-bronchiolar neoplasms in BALB/c female mice

Lungs from 505 (21.1%) of 2,397 untreated control female BALB/c mice examined at various age intervals up to 1,001 days contained alveolar-bronchiolar neoplasms. Tumors were evaluated for histomorphological type, degree of differentiation, and size. Most of the tumors (286 of 505 or 56% of those examined) were of the papillary type and 450 of 505 (89.1%) were well differentiated. The incidence of the solid type and the well differentiated tumors was highest in the smallest size group (less than 0.5 mm) while that of the papillary and mixed types and the moderately and poorly differentiated tumors was highest in the larger size groupings. One hundred twenty-seven of 131 (97%) of all solid tumors were well differentiated while a lower percentage of papillary and mixed types (86.7% and 85.2%, respectively) were well differentiated. The mean age of mice with tumors from each histomorphological type, degree of differentiation, and size grouping also was determined.