A simple and inexpensive method for investigating microbiological, enzymatic, or inorganic catalysis using standard histology and microbiology laboratory equipment: assembly, mass transfer properties, hydrodynamic conditions and evaluation.

We introduce a generic, simple, and inexpensive method for performing microbiological, enzymatic, or inorganic catalysis with solids using standard histology and microbiology laboratory equipment. Histology cassettes were used to standardize hydrodynamic conditions and to protect the catalysts and their solid supports. Histology cassettes have the following advantages: they are readily available, inexpensive, solvent and acid resistant, automatable, and the slots in the cassette walls allow liquid to circulate freely. Standard Erlenmeyer flasks were used as reaction vessels. We developed a new camera to observe the movement and position of the histology cassettes as well as the liquid in the Erlenmeyer flasks. The camera produces a stable image of the rotating liquid in the Erlenmeyer flask. This visualization method revealed that in a 250 ml Erlenmeyer flask, stable operating conditions are achieved at a shaking frequency of 300 rpm and a fill volume of 30 ml. In vessels with vertical walls, such as beakers or laboratory bottles, the movement of the histology cassette is not reproducible. Mass transfer characterization using a biological model system and the chemical sulfite-oxidation method revealed that the histology cassette does not influence gas-liquid mass transfer.

The late effects of selected immunosuppressants on immunocompetence, disease incidence, and mean life-span. III. Disease incidence and life expectancy.

The effect of various immunosuppressive treatments on mean life-span and disease incidence have been studied. Significant life shortening was seen only in mice which recieved X-irradiation early in life and can be ascribed primarily to an increased incidence of certain malignancies. Marginal life shortening was seen in cyclophosphamide-treated animals, however, survival patterns between those and control animals did not differ until 30 months of age and the magnitude of life-shortening never approached that seen in X-irradiated animals. Thymectomy, splenectomy or cortisone treatment did not alter survival. All immunosuppressive treatments enhanced mortality due to non-neoplastic diseases, however, only a small percentage of animals die with these disease entities. With the exception of cortisone all immunosuppressive treatments increased the incidence of neoplastic disease. However, their effects on various neoplastic processes were variable and unpredictable. Four primary patterns in terms of relative immune competence, disease incidence and life expectancy were seen. Thus, immunodepression may of may not correlate with increased disease incidence, which in turn may or may not have a life-shortening effect. These findings are discussed in terms of the marked reduction of both humoral and cell-mediated immunity normally seen in aged mice and the significance of postulated immune surveillance mechanisms to survival.

Qualitative and quantitative evaluation of prostatic histomorphology in rats following chronic treatment with finasteride, a 5-alpha reductase inhibitor.

OBJECTIVE: To determine any potential direct and/or indirect effects of elevated intraprostatic T levels on the prostates of rats chronically (1-2 years) exposed to high doses (160 mg/kg/day) of finasteride, a selective inhibitor of 5-alpha reductase. METHODS: Sprague-Dawley male rats were administered daily finasteride by oral gavage. Prostates from all rats were weighed, fixed in 10% neutral buffered formalin, and processed for light microscopic examination. The volume fractions of the prostatic glandular and stromal compartments were quantitated by morphometric analysis. RESULTS: Administration of finasteride at doses of 20, 40, and 80 mg/kg/day for one year resulted in a significant (P < or = 0.05) decrease in prostatic weight; prostatic atrophy was evident by light microscopy. Morphometric analysis of the prostate showed that chronic finasteride administration resulted in a significant (P < or = 0.001) decrease in the absolute volume of both glandular (-65.2%) and stromal (-57.1%) compartments of the prostate. Furthermore, the total number of epithelial and stromal cells per gland were significantly (P < or = 0.002) decreased in finasteride-treated rats compared with vehicle controls; the magnitude of mean decrease was 69.8 percent and 50.6 percent of controls in epithelial and stromal cells, respectively. In addition, prostates from all two hundred fifty rats in a two-year study were qualitatively evaluated by light microscopy. Administration of finasteride at doses ranging from 2.5 mg/kg/day to 160 mg/kg/day for two years did not result in an increase over the background incidence of prostatic focal hyperplasia or adenoma. No malignant tumors of the prostate were seen in any of the groups. CONCLUSIONS: These studies have demonstrated that the expected pharmacologic effects of finasteride on the prostate are maintained following chronic treatment and that there was no evidence of a direct and/or an indirect effect of elevated intraprostatic T on prostatic morphology in rats.

Effect of alendronate on fracture healing and bone remodeling in dogs.

To examine the effect of alendronate (4-amino-1-hydroxybutylidene bisphosphonate) on fracture repair, the drug was given to mature beagle dogs orogastrically at 2 mg/kg/day for 9 weeks preceding fracture. 16 weeks after fracture, or both before and after fracture (25 weeks). A transverse mid-diaphyseal fracture of the right radius was surgically induced and was stabilized by external coaptation splinting. Fracture healing and bone remodeling were evaluated by radiography, gross and histological examination, and bone histomorphometry. The mechanical properties of the fracture callus were determined by a four-point bending test. Radiographs and gross and microscopic examination demonstrated normal bone healing at the fracture site in all dogs. In dogs that received alendronate during the fracture healing period, at 16 weeks the calluses were approximately 2-3 times larger than those in dogs that received a placebo during the healing period. This is consistent with slower callus bone remodeling, an expected pharmacological effect of the compound. Bone histomorphometry demonstrated that treatment with alendronate did not inhibit bone formation or mineralization. Mechanical testing showed that the ultimate load at failure and the flexural rigidity of both the fractured and contralateral intact bone were unaffected by treatment with alendronate. Therefore, in this study, treatment with alendronate before or during fracture healing, or both, resulted in no adverse effects on the union, strength, or mineralization of bone in mature beagle dogs.

Induction of reversible urothelial cell hyperplasia in rats by clorsulon, a flukicide with weak carbonic anhydrase inhibitory activity.

Clorsulon, a flukicide registered for use in treating Fasciola hepatica infections in cattle, has induced urinary bladder urothelial cell hyperplasia in rats at oral doses of 30 mg/kg/day or more. Despite previous testing at doses above this threshold, this lesion had not been found in subchronic or chronic toxicity studies in rats. After ruling out the presence of a contaminant as the causative factor in producing this lesion, a study was conducted in which clorsulon increased the pH and altered the electrolyte composition of urine, consistent with its weak carbonic anhydrase inhibitory activity. The acid/base balance of the diet markedly affected the threshold for induction of the urothelial cell hyperplasia: acidification by addition of 5% ammonium chloride to the diet reduced the incidence and severity. In additional studies it was found that the urothelial cell hyperplasia was most pronounced after 1 week of treatment compared with daily exposure for either 5 or 15 wk. The reversibility of the hyperplasia despite continued treatment confirms that the hyperplasia is not a preneoplastic lesion, a conclusion supported by negative studies of carcinogenicity in rodent bioassays of clorsulon and other drugs with carbonic anhydrase inhibitory activity.

Electrochemical threshold conditions during electro-optical switching of ionic electrophoretic optical devices.

Electro-optical modulation by electrophoresis of dye ions is a promising technique for applications such as electronic paper displays and nonmechanical beam steering devices. To achieve a sufficient response rate in these devices, the transition time between two different optical states can be decreased by increasing the magnitude of the voltage applied across the electrodes, but this also leads to irreversible and undesirable electrochemical reactions. An electron tunneling model has been developed to describe the electrochemical reaction and to better understand the conditions determining its onset. The model gives rise to three predictions that were subsequently confirmed experimentally: the magnitude of the applied surface charge density should determine the rate of electrochemical activity, the bulk concentration of ions in the solution should shift the threshold voltage at which electrochemical reactions occur, and the reaction rate should be substantially enhanced around nanometer-sized bumps on the electrode surface. Applying this new understanding, the transition time of a device incorporating porous zinc antimonate (ZnSb2O6) electrodes and a solution of Methylene Blue dye in methanol was reduced by a factor of approximately 20.

Photoluminescence emission profiles of Y(2)O(3) : Eu films composed of high-low density stacks produced by glancing angle deposition.

Periodic high-/low-index film stacks composed of Y(2)O(3) : Eu were grown by glancing angle deposition on silicon and fused silica substrates. Postdeposition annealing at temperatures from 600 to 1000 degrees C for 1 h in air was performed to activate photoluminescence. Absolute photoluminescence spectra were obtained as a function of observation angle. The angular emission distribution was non-Lambertian, with peak emission at angles of 50 to 60 degrees with respect to substrate normal. Spectroscopic transmittance and ellipsometry measurements were performed to characterize the films. Using this description, we were able to reproduce the angular photoluminescence patterns of the films.

Comparative study of potential for bisphosphonates to damage gastric mucosa of rats.

Bisphosphonates have generally few clinical adverse effects, the most common being gastrointestinal disturbances. It is generally believed that bisphosphonates with a primary amine are more irritating to the gastrointestinal tract than those without a primary amine. The objective of this study was to compare the gastric irritation potential of an amino bisphosphonate (alendronate) to that of two nonamino bisphosphonates (risedronate and etidronate) in a rat model at pharmacologically equivalent and clinically relevant doses. The doses used were 1, 5, 10, and 30 mg/kg/day for alendronate and risedronate and 40, 200, 400, and 1200 mg/kg/day for etidronate. These doses represent 5-150 times the recommended clinical dose. The drugs were given orally, daily by gavage for four weeks. The gastric irritation potential was assessed by gross and microscopic evaluation of multiple sections of the stomach. This study showed that, at pharmacologically equivalent doses, the gastric irritation potential for alendronate is no greater than that for etidronate or risedronate.

Esophageal irritation due to alendronate sodium tablets: possible mechanisms.

Animal studies were done using an in vivo dog model to examine the possible mechanism for the esophageal adverse events reported with alendronate sodium tablets. These studies showed that under low pH conditions alendronate sodium can cause esophageal irritation. No esophageal irritation occurred at pH 3.5 or higher where the drug exists primarily as the sodium salt. The animal studies also showed that alendronate sodium can exacerbate preexisting esophageal damage. Exposure of the esophageal mucosa for a prolonged period to alendronate sodium tablet can also cause mild esophageal irritation. These findings suggest that the esophageal irritation in patients taking Fosamax can be from prolonged contact with the tablet, reflux of acidic gastric contents with alendronate sodium, and exacerbation of preexisting esophageal damage. The findings also suggest that other bisphosphonates can cause esophageal injury under similar conditions.

Effects of the bisphosphonate, alendronate, on parturition in the rat.

Alendronate is a bisphosphonate which inhibits bone resorption. In female fertility studies in rats, dosages of 10 and 15 mg/kg/day produced physical signs of toxicity at parturition, including tremors, dystocia, and death in the dams and these were associated with neonatal deaths. These effects were associated with hypocalcemia in the dams but the fetuses were normocalcemic. There was no one critical period of treatment during gestation for these effects; they were instead proportional to length of treatment. Neonatal deaths were due to protracted deliveries rather than a direct effect of alendronate on the pups. Intravenous calcium supplementation (9.3 mg/dam) prevented the above-described adverse effects on dams and pups. In rats, fetal skeletal ossification is at its greatest rate in late gestation, and during this period free calcium is preferentially transported to the fetal compartment. The females meet this increased demand by calcium mobilization via increased bone resorption. We conclude that the maternotoxicity of alendronate in rats is due to the designed pharmacologic activity of this bisphosphonate; the drug prevents bone resorption and thereby denies the dam an important source of calcium at a time when fetal demand for this mineral is at its peak. The alendronate-induced hypocalcemia adversely affects parturition because uterine muscle contraction is a calcium-dependent process.

Rapid induction of hyperplasia in vitro in rat bladder explants by elevated sodium ion concentrations and alkaline pH.

The effects of alkaline pH and elevated sodium concentrations in culture medium on rat bladder explants for 1, 2, and 3 weeks were investigated by continuous BrdU labeling and histopathology. Increasing the sodium chloride concentration of normal medium by 50 or 100 mM caused slight urothelial hyperplasia with statistically significant increases in labeling in week 2 (50 mM) and at all time points with 100 mM NaCl. Cytotoxicity was seen in the high salt group. Increasing the pH from 7.2 to 7.8 and 8.2 also caused a slight hyperplastic response with significant increases in labeling and cytotoxicity at pH 8.2. However, bladder explants treated at pH 7.8 or 8.2 with excess sodium concentrations of 50 to 100 mM had a more marked hyperplastic response with evidence of cytotoxicity as well. There were significant increases in the labeling index (6.4- to 15.0-fold relative to control) after 1 week, with the maximum response at 100 mM sodium/pH 8.2. These results suggest that alkaline pH and elevated sodium concentration have a direct mitogenic effect on rat urothelial cells with some cytotoxicity-induced regenerative cell proliferation as well. These in vitro results in an organ culture system are in agreement with in vivo studies that have shown an important role for elevated urinary cation concentrations and pH in the stimulation of DNA synthesis, induction of hyperplasia, and tumor promotion in rat bladder epithelium.

Exposure of rats to lead nitrate in utero or postpartum; effects on morphology and behavior.

Female rats were administered lead (Pb), as the nitrate salt, on day 17 of pregnancy (5 or 25 mg/kg i.v.) or throughout lactation (5 or 25 mg/kg/day p.o.). There were adverse effects on weights of females receiving Pb on day 17. At 25 mg/kg i.v. gestation was significantly prolonged. In both groups treated intravenously, average pup weight on day 1 postpartum was significantly reduced and there was a significantly higher mortality than in controls, and hydrocephalus occurred. Survival rate and weight gain of pups from dams that received Pb throughout lactation was not different from controls. Brain weights and histomorphology of all groups was normal. Behavior in male offspring, as measured by open-field activity, rotorod or passive avoidance tests, was unaffected by exposure to Pb.

Spontaneous nephropathies in rats.

Spontaneously occurring diseases of the kidneys are very common in laboratory rats. These diseases include chronic progressive nephrosis, nephrocalcinosis, renal tubular epithelial hyaline droplets, renal tubular hypertrophy, and renal tubular basophilia. As increasing numbers of rats are used in long-term toxicity and carcinogenicity studies, recognizing spontaneously occurring renal lesions and understanding their etiology and pathogenesis are important in making an assessment of the safety of drugs and chemicals that are being tested. The purpose of this paper is to review the incidence, morphology, and pathogenesis of these spontaneous diseases. Some of the factors that alter the incidence and/or severity of these spontaneous diseases will also be discussed.

Continuous alendronate treatment throughout growth, maturation, and aging in the rat results in increases in bone mass and mechanical properties.

Alendronate (4-amino-1-hydroxybutylidene bisphosphonate) is a novel amino bisphosphonate that is being developed for the treatment of osteolytic bone disorders such as osteoporosis. As part of a 2-year carcinogenicity study, we investigated the morphologic and biomechanical effects of long-term alendronate (ALN) therapy, given throughout skeletal growth, maturation, and aging, on rat vertebrae and femora. Three treatment groups, receiving either deionized water, low- (1.00 mg/kg), or high-dose (3.75 mg/kg) ALN, were given daily oral treatment for 105 weeks. Results from mechanical tests indicate that ALN therapy (in males) increased the vertebral ultimate compressive load by 96% in the high- and 51% in the low-dose groups when compared with controls. ALN similarly increased the male ultimate femoral bending load by 59% in the high- and 31% in the low-dose groups. Vertebrae and femora from female rats treated with both high- and low-dose ALN also failed at significantly higher loads than controls, but no differences were seen between low- and high-dose groups. Morphologic analysis of both male and female vertebrae revealed a dose-dependent increase in area fraction of bone. Rats receiving high-dose ALN had a greater area fraction of bone than those receiving low doses. Both groups were greater than controls. Thus, the administration of ALN resulted in increased femoral cortical bending load when compared with control animals, as well as increased vertebral ultimate compressive load commensurate with a dose-related preservation of vertebral bone.(ABSTRACT TRUNCATED AT 250 WORDS)