PubMed HealthSearch

Biomedical subjects

R Read

Publications and source records attributed to R Read.

At least 19 recordsLinked to original sources

beta-Cyclodextrin: 52-week toxicity studies in the rat and dog.

A 52-wk toxicity study by dietary administration was performed in Sprague-Dawley rats and in pure-bred beagle dogs with beta-cyclodextrin, a starch derivative that acts as a molecular inclusion agent. Doses of 0 (control), 12,500, 25,000 and 50,000 ppm were selected for the rat study, and 0 (control), 6200, 12,500 and 50,000 ppm were selected for the dog study. The liver and kidney were identified at the histopathological examination as target organs for toxicity in the rat at doses of 50,000 and 25,000 ppm, with the hepatic changes associated with increased plasma liver enzyme and reduced plasma triglyceride concentrations. In the dog study, there was no pathological evidence of systemic toxicity, although there were minor changes in urinalysis and biochemical parameters and a slightly higher incidence of liquid faeces. These changes were considered to be of no toxicological importance. The results in these studies, therefore, indicate that the non-toxic effect level was 12,500 ppm in the rat (equivalent to 654 or 864 mg/kg/day for males or females, respectively) and 50,000 ppm in the dog (equivalent to 1831 or 1967 mg/kg/day for males or females, respectively).

Analysis of Variance

Hyaluronic acid (hyaluronan) in experimental osteoarthritis.

We studied the effects of intraarticular (ia) administration of hyaluronic acid (HA) (Mw approximately 9 x 10(5)) (Artz) on cartilage integrity and release into synovial fluid (SF) of keratan sulfate peptides (KS-pep) in an ovine model of early osteoarthritis (OA) induced by meniscectomy. Five consecutive weekly injections of HA (2 ml, 10 mg/ml) or saline (2 ml) were initiated 16 weeks after meniscectomy, and animals were sacrificed 5 weeks after the last injection. SF was sampled 8, 16, 23, and 26 weeks postoperation. In the saline injected animals KS-pep levels increased progressively in SF, relative to nonoperated controls (p < 0.05). KS-pep levels in SF of the HA treated group also increased, but were not statistically different from controls. Using a modified Mankin histological scoring system, cartilage at necropsy of HA injected joints showed less damage than similar regions of saline treated animals. A new mechanism for the protective effects of HA on cartilage is proposed.

Animals

The effects of intraarticular hyaluronan on cartilage and subchondral bone changes in an ovine model of early osteoarthritis.

OBJECTIVE: Intraarticular (ia) hyaluronan (HA) is reported to provide symptomatic relief in osteoarthritis (OA); however, there is limited information on the effects that this treatment may have on joint articular cartilage or subchondral bone. Our objective was to address this issue using an ovine model of early OA. METHODS: Unilateral medial meniscectomy was performed in 10 adult merino sheep, and 5 unoperated animals were used as controls (UOC). Sixteen weeks postmeniscectomy, joints of 5 operated animals were injected with 2 ml of HA (Artz, 10 mg/ml, M(r) = 0.9 x 10(6) Da) ia while the remaining 5 operated animals received 2 ml of sterile saline ia. This protocol was continued for a further 4 weeks. All animals were sacrificed 5 weeks after the last injection; however 3 weeks before sacrifice they were given tetracycline (20 mg/kg intravenously) weekly. Bone slabs, including articular cartilage, were cut from the medial tibial plateaux and femoral condyles, processed for histology, histomorphometry and fluorescence microscopy to assess articular cartilage and subchondral bone pathology. RESULTS: Meniscectomy and saline treatment increased osteoid volume and surfaces as well as increased the extent of tetracycline labelling of the subchondral bone relative to UOC. The articular cartilage also exhibited a significantly higher modified Mankin's score than UOC. In the HA injected group the aforementioned articular cartilage and subchondral bone changes were modified such that the observed variables were indistinguishable from UOC. CONCLUSION: Using this animal model intraarticular HA appeared to limit the development of articular cartilage and subchondral bone changes characteristic of early OA.

Animals

Animal models of early osteoarthritis: their use for the evaluation of potential chondroprotective agents.

Medial meniscectomy was undertaken in adult merino sheep and after 16 weeks exercise each group was administered five weekly intra-articular injections of saline, pentosan polysulphate (PPS), hyaluronic acid (HA) or a combination of PPS + HA. Gait analysis and x-rays were undertaken before and after drug treatment. At sacrifice (26 weeks), joints were examined for gross pathological and histochemical changes. Only the PPS-treated group showed an improvement in gait, with low radiological and histology scores. The HA-treated group showed similar but less significant changes to these parameters.

Animals

Interaction of Haemophilus influenzae with mucus, cilia, and respiratory epithelium.

One nontypeable laboratory strain and five nontypeable clinical isolates of Haemophilus influenzae from sputum were investigated. Bacteria replicated from 10(4) to 10(8) cfu/ml over 24 h in an organ culture of human respiratory mucosa with only the intact mucosal surface exposed. By transmission electron microscopy, bacteria were not seen in association with normal respiratory epithelium, even after incubation for 24 h. H. influenzae infection caused patchy and occasionally confluent damage to epithelium, and the bacteria associated only with structurally damaged cells. Scanning electron microscopy revealed increased mucus, and slowed ciliary beat frequency was measured by photometry. Fimbriation of H. influenzae increased buccal cell adherence but did not facilitate association with normal or damaged respiratory epithelium or increase epithelial damage, indicating that adhesins other than fimbriae are present. Interactions with mucus, cilia, and epithelium are likely to be important in the pathogenesis of H. influenzae respiratory infections.

Cilia

Evidence for intestinal release of absorbed selenium in a form with high hepatic extraction.

Selenium is readily absorbed from the gastrointestinal tract and utilized for synthesis of selenoproteins. Roles of intestine, liver, and selenoprotein P in this process were evaluated. Rats were given 75Se-selenite by stomach tube, and distribution of 75Se was followed for 3 h. A high portal vein plasma-to-hepatic vein plasma ratio of 75Se 15 min after 75Se administration and earlier uptake by liver than by other tissues indicated avid hepatic extraction of absorbed selenium from portal vein blood. The results of gel filtration of plasma taken 15 min after 75Se administration suggested that the 75Se was in the form of small molecules with some affinity for protein. Immunoprecipitation studies using plasma indicated that 75Se began to appear in selenoprotein P between 15 and 30 min after intragastric administration. To evaluate the role of the liver in the fate of absorbed selenium, rats with portacaval shunts, in which absorbed selenium bypasses the liver, were compared with sham-operated rats. After intragastric administration of selenium, uptake by the liver and incorporation into selenoprotein P were diminished in rats with portacaval shunts but kidney uptake and urinary excretion were increased. This suggests that hepatic extraction of absorbed selenium from portal vein blood decreases its entrance into the systemic circulation. The results of this study indicate that intestine releases absorbed selenium into portal blood in a small-molecule form, designated A-Se, which is highly extracted by the liver. The liver takes up A-Se better than other tissues because of a high extraction capacity and the fact that it is the first organ through which the blood from the intestine passes.

Absorption

The interaction of Streptococcus pneumoniae with intact human respiratory mucosa in vitro.

The interaction of Streptococcus pneumoniae with human ciliated upper respiratory mucosa was studied in an agar-embedded organ culture of nasal turbinate tissue, which only exposed the intact epithelial surface and its secretion. The ciliary beat frequency, measured along the edge of the organ culture, was slowed by 13% in the presence of S. pneumoniae after 16 h (p less than 0.05) compared with the control, and by 24% after 24 h (p less than 0.01). Light microscopy showed bacteria in a thickened gelatinous layer, which obscured the surface of the organ culture. Transmission and scanning electron microscopy confirmed the association of bacteria with the gelatinous layer above an epithelial surface which showed only minor changes compared to uninfected control organ cultures. Contact between bacteria and normal or damaged epithelial cells was not seen. S. pneumoniae in organ culture developed projections from their surface, which were not present after broth culture. S. pneumoniae interactions with epithelial-derived secretions, the formation of a thickened gelatinous layer, and the effects of bacterial toxins on ciliary motility, may be important during colonization of the respiratory tract.

Cilia

The cDNA for rat selenoprotein P contains 10 TGA codons in the open reading frame.

Selenoprotein P is a plasma protein recently purified and characterized as containing 7.5 +/- 1.0 selenium atoms/molecule as selenocysteine. In rats maintained on a defined diet containing nutritionally adequate amounts of selenate as the sole selenium source, over half the selenium in plasma is accounted for by selenoprotein P. Its cDNA has been cloned from a rat liver library and sequenced. The sequence is highly unusual, containing 10 TGA codons in its open reading frame prior to the TAA termination codon. TGA designates selenocysteine in other selenoproteins, and limited peptide sequencing that included the amino acids encoded by two of the TGA codons verified that they correspond to selenocysteine. The deduced 366-amino acid sequence is histidine- and cysteine-rich and contains 9 of its selenocysteines in the terminal 122 amino acids. Comparison of the deduced amino acid sequence of selenoprotein P with those of other selenoprotein reveals no significant similarities. Selenoprotein P represents a new class of selenoproteins and is the first protein described with more than 1 selenocysteine in a single polypeptide chain. The primary structure of selenoprotein P suggests that it might be responsible for some of the antioxidant properties of selenium.

Amino Acid Sequence

Effects of Bordetella pertussis infection on human respiratory epithelium in vivo and in vitro.

Bordetella pertussis infection probably involves attachment to and destruction of ciliated epithelial cells, but most previous studies have used animal tissue. During an epidemic, nasal epithelial biopsy specimens of 15 children (aged 1 month to 3 1/2 years) with whooping cough were examined for ciliary beat frequency, percent ciliation of the epithelium, and ciliary and epithelial cell ultrastructure. In addition, the in vitro effects of filtrates from a 24-h broth culture and of tracheal cytotoxin derived from B. pertussis on human nasal tissue organ culture were measured. B. pertussis was cultured from nasal swabs from 12 children. The mean ciliary beat frequency of their nasal biopsy specimens, 11.3 Hz (range, 10.4 to 13.0 Hz) was similar to that found in biopsy specimens from 10 normal children (mean, 12.5 Hz; range, 11.8 to 13.5 Hz). The abnormalities of the epithelium observed in 14 of 15 patients were a reduction in the number of ciliated cells, an increase in the number of cells with sparse ciliation, an increase in the number of dead cells, and extrusion of cells from the epithelial surface. In vitro, neither culture filtrate nor tracheal cytotoxin had any acute effect on ciliary function, but culture filtrate and tracheal cytotoxin (1 and 5 microM, respectively) caused extrusion of cells from the epithelial surface of turbinate tissue, loss of ciliated cells, an increased frequency of sparsely ciliated cells, and toxic changes in some cells. These changes were dose dependent and progressive, and between 36 and 90 h ciliary beating ceased. The observations made with patient tissue confirm that B. pertussis infection damages ciliated epithelium, and the in vitro experiments suggest that tracheal cytotoxin may be responsible for the abnormalities observed in vivo.

Bacterial Adhesion

Response of rat selenoprotein P to selenium administration and fate of its selenium.

Selenoprotein P is a glycoprotein that contains greater than 60% of the selenium in rat plasma. Physiological experiments were undertaken to gain insight into selenoprotein P function. Selenium-deficient rats were injected with doses of selenium ranging from 25 to 200 micrograms/kg, and the appearance of selenoprotein P was compared with the appearance of glutathione peroxidase activity in plasma and in liver. Selenoprotein P concentration increased to 35% of control by 6 h, whereas glutathione peroxidase activity increased minimally or not at all. Moreover, in rats given 100 and 200 micrograms selenium/kg, selenoprotein P reached 75% of its concentration in control rats at 24 h, whereas glutathione peroxidase activity reached only 6% of control. Cycloheximide pretreatment blocked the appearance of selenoprotein P in response to selenium injection. Male and female rats had similar concentrations of selenoprotein P. Partially purified selenoprotein P and plasma glutathione peroxidase labeled with 75Se were administered intravenously to selenium-deficient and control rats. 75Se given as selenoprotein P disappeared more rapidly from plasma than did 75Se given as glutathione peroxidase. Selenium deficiency did not significantly affect 75Se disappearance from plasma. At 2 h, brain, but not other tissues, took up more 75Se in selenium-deficient rats than in control rats when 75Se was given as selenoprotein P. This suggests that brain has a specific uptake mechanism for selenium given in the form of selenoprotein P. These results demonstrate that several physiological properties distinguish selenoprotein P from glutathione peroxidase. However, they do not clearly indicate its function.

Animals

Effects of human neutrophil elastase and Pseudomonas aeruginosa proteinases on human respiratory epithelium.

It has been suggested that proteinase enzymes could play an important role in the pathogenesis of chronic bronchial infections including bronchiectasis and cystic fibrosis (CF). Because Pseudomonas aeruginosa frequently colonizes the respiratory tract in bronchiectasis and CF, we examined the in vitro effects of human neutrophil elastase (HNE) and proteinase enzymes produced by P. aeruginosa (elastase: PE; alkaline proteinase: PAP) on the ciliary beat frequency (CBF) and ultrastructure of human nasal ciliated respiratory epithelium. HNE (500 micrograms/ml) progressively reduced CBF and caused marked epithelial disruption; lower concentrations (100 and 20 micrograms/ml) also caused epithelial disruption but without slowing CBF. The effects of HNE (500 micrograms/ml) were completely abolished by adding alpha 1-antitrypsin (5 mg/ml). There was no synergy between HNE and pyocyanin, a product of P. aeruginosa which slows CBF. PE in phosphate-buffered saline also caused epithelial disruption without slowing CBF; however, PE in medium containing divalent metal ions caused CBF slowing as well as epithelial disruption at 100 micrograms/ml. PAP (500 micrograms/ml) had almost no effect on ciliated epithelium. The effects of HNE and PE on nasal and bronchial epithelium obtained from the same patient were similar. Light and transmission electron microscopy revealed that HNE and PE were cytotoxic and caused detachment of epithelial cells from neighboring cells and the basement membrane. There was cytoplasmic blebbing of the cell surface and mitochondrial damage; however, no increase of abnormalities in the ultrastructure of cilia on living cells was seen. These results support the hypothesis that HNE and PE contribute to the delayed mucociliary clearance and epithelial damage that is observed in patients with chronic bronchial infection.

Bronchi

Recent advances in animal models for evaluating chondroprotective drugs.

While a variety of animal models have been described to evaluate the effects of antiarthritic and chondroprotective drugs on cartilage metabolism, most cannot be said to truly reproduce the temporal changes that occur in human osteoarthritis (OA). Total meniscectomy is a common orthopedic procedure in humans and frequently leads to OA in later years. We investigated the effects of unilateral medial meniscectomy in sheep knee joints subjected to moderate regular exercise. Morphological and biochemical studies of joint cartilage after 6 months revealed slowly progressive changes similar to those seen in early OA, characterized by cartilage fibrillation, chondrocyte hypertrophy, matrix proliferation and marginal osteophyte formation. The proteoglycans synthesized contained more chondroitin-4-sulphate than chondroitin-6-sulfate.

Animals

Selenium and amino acid composition of selenoprotein P, the major selenoprotein in rat serum.

Selenoprotein P is the second plasma selenoprotein to be purified. It is a glycoprotein and has been shown to be distinct from plasma glutathione peroxidase. This study characterizes selenoprotein P further. Deglycosylation of the protein shifts its migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis from Mr 57,000 to Mr 43,000, indicating it has a substantial carbohydrate component. Measurement of selenium indicates a selenium content of 7.5 +/- 1.0 atoms/molecule based on a polypeptide weight of 43,000. Amino acid analysis accounts for all the selenium as selenocysteine. The protein is also rich in cysteine (17 residues) and histidine (23 residues). Fragmentation of selenoprotein P by trypsin and by cyanogen bromide produces peptides with varying selenium content. This indicates that selenium-rich regions of the protein exist. The concentration of selenoprotein P determined by radioimmunoassay in serum from control rats is 26.3 +/- 4.5 micrograms/ml and in serum from selenium-deficient rats it is 2.7 +/- 0.8 micrograms/ml. Depletion of selenoprotein P from control serum using an immunoaffinity column indicates that over 60% of serum selenium in the rat is contained in this protein. These results demonstrate that selenoprotein P is the major form of selenium in rat serum. It is the first selenoprotein described which has more than one selenium atom/polypeptide chain.

Amino Acids

Improved cannulation method for extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation has been shown to be useful for patients in reversible cardiogenic shock. Effective arterial cannulation techniques for infants have been developed that are simple to use and require minimal subsequent vascular repair or reconstruction after removal. Groin cannulation in adults frequently requires bidirectional arterial cannulation to ensure adequate distal perfusion as well as frequent complex arterial repairs after discontinuation. We describe a simple arterial cannulation technique using a single right-angle, high-flow arterial cannula. With this technique adequate bidirectional arterial perfusion is maintained with a single arterial cannula while the need for vascular repairs or reconstruction is minimized.

Catheterization, Peripheral

Bronchial anomaly of the right upper lobe.

This case report presents a rare anomaly of right upper lobe bronchial anatomy. During routine right upper lobe resection for carcinoma, a common right upper and middle lobe bronchus was found. The resection was completed as a right upper and middle bilobectomy. Knowledge of this uncommon variant was beneficial in performing the pulmonary resection. A review of the literature is presented.

Adenocarcinoma

Clinical and laboratory findings in the Paul-Bunnell negative glandular fever-fatigue syndrome.

Forty-one patients with recurrent fatigue were studied for evidence of symptom clustering, abnormal laboratory findings and infection with novel viruses. Symptom enquiry and investigations were repeated 4 months later. Four patients were found to have diseases compatible with their symptoms. In those remaining, an initial acute onset of symptoms was associated with an intermittent course, tender glands and a raised number of T suppressor lymphocytes. Raised numbers of T suppressor lymphocytes at follow-up correlated with resolution of symptoms. Antibodies to human herpesvirus 6 (HHV-6) were found in 75% of the patients as compared to 53% of a control group and more patients than controls were strongly seropositive. Some patients with chronic fatigue have a pattern of illness which suggests glandular fever, although acute infection with Epstein-Barr virus (EBV) is not demonstrated. Primary or reactivation infection with HHV-6 may have a role in this syndrome.

Adolescent