Effect of mu-opioids morphine and buprenorphine on the development of adjuvant arthritis in rats

OBJECTIVE AND DESIGN: On the basis that endogenous opioids play a role in the physiological response to inflammation, this study tests the anti-arthritic effects of a mu-opioid agonist, morphine and the partial mu-agonist, buprenorphine. MATERIAL: Male Lewis rats were used. TREATMENT: Rats were inoculated subcutaneously with 0.05 ml of Freund's complete adjuvant (5 mg/ml) into the right hind paw to produce adjuvant arthritis. Morphine (either 10 to 60 mg/kg/day s.c. bolus or 60 mg/kg/day s.c. infusion) and buprenorphine (0.65 +/- 0.06 mg/kg/day, orally), respectively, were administered for 3 days during the primary inflammatory phase of adjuvant arthritis. METHODS: The progression of adjuvant arthritis was monitored every three days by body weight change and hind limb oedema (ipsilateral and contralateral). On day 21 the animals were sacrificed and histology and radiography of the contralateral limb were performed. In rats receiving Freund's adjuvant and no drug treatment, the incidence of arthritis was 89%. Effect was expressed as the pooled severity index (PSI) derived from the arithmetic average of the volume, histology and radiography scores in the contralateral hind limb. RESULTS: Buprenorphine had no effect on experimental arthritis (PSI control vs treated: 242 +/- 28 vs 253 +/- 28%). In contrast, morphine by subcutaneous injection twice daily (10 to 60 mg/kg/day) but not by subcutaneous infusion (60 mg/kg/day) was found to attenuate the progression of adjuvant arthritis in a dose-dependent manner. This indicates that the anti-arthritic effects of morphine are opioid receptor mediated (ED50, 58 +/- 9 mg/kg) and suggests that the local concentration reached effective levels only after subcutaneous injection. It is also possible that the high doses of morphine were anti-inflammatory through effects at the kappa receptor. However, these high doses of morphine produced death in one third of the rats, the calculated lethal dose (LD50, 63 +/- 2 mg/kg) being close to the effective dose. CONCLUSION: Anti-arthritic effects of morphine are opioid receptor mediated but morphine use for this indication is restricted by its adverse effects.     

Experimentally induced Mycoplasma pneumoniae pneumonia in chimpanzees

Eight chimpanzees were examined. Two served as negative control and six inoculated with Mycoplasma pneumoniae became colonized. Colonization persisted for 28-68, 16-50 and 21 days with an average duration of 47, 32.5 and 21 days in the oropharyngeal, tracheal and lung tissues, respectively. Mycoplasma titers ranged from 10(8) to 10(1) color-changing units per specimen during the course of the infections. Seroconversion occurred within 12-15 days and peak antibody titers ranged from 1.256 to 1.1024 and developed between days 28 and 48 post-inoculation. Positive cold agglutinin titers were detected between 12 to 15 days and peak titers ranged from 1:80 to 1:640. Significant increases in sIgA and IgG immunoglobulin antibody levels were detected in lung lavage fluids. Unlike the many other experimentally infected animals examined, chimpanzees infected with M. pneumoniae had positive X-ray findings, developed cold agglutinins and showed overt signs of disease. These signs include persistent cough, low grade fever, rhinitis, oropharyngitis, diarrhea, and loss of appetite. Peak severity of disease corresponded with peak lung colonization, and the detection of cold agglutinins and positive X-ray findings. The microbiological, serological and clinical aspects of pneumonia induced in chimpanzees was similar to naturally occurring primary atypical pneumonia in humans.     

Repair of distal biceps tendon ruptures in athletes

Ten athletes with distal biceps tendon ruptures that had been anatomically repaired with a double-incision techniques were reviewed to determine their functional recovery. All of the patients were men, with an average age of 40 years (range, 25 to 49). Eight of the 10 patients were weight lifters or body builders, and 7 had participated on a competitive level at some point in their athletic careers. Six injured their dominant extremity, and 4 their nondominant extremity. Isokinetic muscle testing of supination and flexion was performed in 8 patients and the results were compared to a control group. Followup averaged 50 months (range, 12 to 105). Patients uniformly graded their subjective results as excellent, with a group mean rating of 9.75 on a 10-point scale. All athletes returned to full, unlimited activity. The contour of the biceps muscle was restored in all cases. Isokinetic muscle testing demonstrated that in those patients with a repaired dominant extremity, supination strength and endurance was normal; in flexion, they had normal strength, but averaged 20% less endurance. Testing of the group that had the nondominant extremity repaired revealed a supination strength deficit of 25%, but normal endurance. Flexion strength and endurance were essentially normal in this group. Anatomic repair of a distal biceps tendon rupture gives consistently excellent subjective and good objective results in athletes, particularly for those sports with high strength demands such as weight lifting and body building. Rehabilitation of the operated arm, especially the repaired nondominant extremity, should be emphasized.     

Chronic ethanol increases N-methyl-D-aspartate-stimulated nitric oxide formation but not receptor density in cultured cortical neurons

The effects of prolonged ethanol exposure on excitatory amino acid receptor stimulated nitric oxide (NO) formation were examined in primary rat cortical neuronal cultures. Chronic ethanol (4 days, 100 mM) potentiated N-methyl-D-aspartate (NMDA)-stimulated NO formation as determined by measuring the conversion of [3H]arginine to [3H]citrulline. In contrast, chronic ethanol had no effect on NO formation stimulated by kainate, alpha-amino-3-hydroxy-5-methyl-4-isoxalonepropionic acid, or the calcium ionophore ionomycin. Potassium chloride-stimulated NO formation was also enhanced by chronic ethanol treatment, but this effect was not seen in the presence of the ionotropic glutamate receptor antagonists MK-801 and 6-cyano-7-nitroquinoxaline-2,3-dione. Immunoblot analysis of expression of NR1, NR2A, and NR2B receptor subunits showed no difference between control and chronic ethanol-treated cultures. In support of this apparent lack of change in receptor density, there was no difference in the specific binding of 125I-MK-801 between control and chronic ethanol-treated groups. These results demonstrate that prolonged ethanol exposure selectively enhanced NMDA receptor-stimulated NO formation, which may play an important role in alcohol dependence, withdrawal, and alcohol-associated brain damage. These results also suggest that chronic ethanol-induced increases in NMDA receptor function may not be due to a simple increase in the number of NMDA receptors or change in NMDA receptor subunit composition but may instead reflect more complicated and subtle changes.     

Beef exports: looking for an opening

BSE, food safety and the veterinarian's role in certification were among matters discussed by the BVA's President, Mr Ted Chandler, at a speech in Ballymena on October 29. Speaking at the BVA's Northern Ireland dinner, at which representatives of Government, local veterinary associations, the farming community and other organisations were present, Mr Chandler emphasised the need for the Government to recognise the veterinary profession's vital contribution to food hygiene and its pivotal role in ensuring that standards are maintained. The main text of his speech is given here.     

Low Probability of Intercept Performance Bounds for Spread-Spectrum Systems

An important application of spread-spectrum (SS) in military communication systems is that of making the signal difficult to intercept by unauthorized receivers. Error-correction coding techniques may be employed to reduce the required input signal-to-noise ratio at the receiver, allowing the system to operate at a lower power level, hence resulting in a lower probability of interception. In the absence of error-correction coding, a specified message bit rate, transmitted signal bandwidth, and required bit-error probability at the receiver will yield a required signal-to-noise ratio for each type of spread-spectrum system. When coding is employed, a specified decoder delay time implies a specified code complexity, and can be used to determine bounds on the required receiver signal-to-noise ratio. These performance bounds are evaluated as functions of the specified parameters. In addition, one may specify a burst interference environment in that the system must operate. Presented is the evaluation of the increase in the upper bound on signal-to-noise ratio as a result of the specification of a correctable single-burst time. This increase indicates an antiintercept /antijam tradeoff.     

Kinetic studies of adsorption of bitter principles and titratable acid from grapefruit juice

Measurement of the initial rates of removal of limonin and naringin from grapefruit juices by several polystyrene and polyacrylic adsorbents has allowed these adsorbents, in the forms as supplied, to be ranked in their order of kinetic effectiveness for removal of the two bitter principles. Partition coefficients of bitter principles between juice and polystyrene adsorbent resins show that the capacity of such resins for naringin increases with specific surface area, but the capacity for limonin appears to increase with specific pore volume. With respect to titratable acid, the two weak base resins, Amberlite IRA-93 and Duolite A378, were equally effective both kinetically and in their capacity for titratable acid; both adsorbed somewhat less than 1 mol of titratable acid from grapefruit juice per equivaient of weak base resin.     

Evidence for a novel bursting mechanism in rodent trigeminal neurons

We investigated bursting behavior in rodent trigeminal neurons. The essential mechanisms operating in the biological systems were determined based on testable predictions of mathematical models. Bursting activity in trigeminal motoneurons is consistent with a traditional mechanism employing a region of negative slope resistance in the steady-state current-voltage relationship (Smith, T. G. 1975. Nature. 253:450-452). However, the bursting dynamics of trigeminal interneurons is inconsistent with the traditional mechanisms, and is far more effectively explained by a new model of bursting that exploits the unique stability properties associated with spike threshold (Baer, S. M., T. Erneux, and J. Rinzel. 1989. SIAM J. Appl. Math. 49:55-71).     

Strength loss in E-glass fibres after exposure to hydrochloric,hydrobromic and hydriodic acids

The corrosion of E-glass fibres by hydrochloric, hydrobromic, and hydriodic acids has been investigated by measuring the loss of mechanical strength of the fibres following immersion in solutions of the acids. Corrosion is greatest in hydrochloric acid and least in hydriodic acid. Curves of percentage strength retention against concentration show well-defined minima for hydrochloric and hydrobromic acids, but not for hydriodic acid. This phenomenon has been attributed to complex ion formation by metal ions in the glass with chloride or bromide ions in the corroding solution. Spectroscopic evidence suggests that ferric ions play an important role in the corroding process.