Absence of detectable pharmacological effects after oral administration of isoxsuprine

Isoxsuprine is reported to be a peripheral vasodilator used in human and veterinary medicine to treat ischaemic vascular disease. In horses, it is generally administered orally to treat navicular disease and other lower limb problems. To define the scope and duration of its pharmacological responses after oral administration, 6 horses were dosed with isoxsuprine HCl (1.2 mg/kg bwt) q. 12 h for 8 days and then tested to assess the duration and extent of pharmacological actions. There was no significant difference between isoxsuprine and control treatment values for heart rate, spontaneous activity, sweat production, anal muscle tone, core and skin temperatures, and cutaneous blood flow. The lack of pharmacological effect following oral administration was in sharp contrast to the marked response following i.v. dosing reported in earlier experiments.

Incidence of sporting injury in New Zealand youths aged 6-15 years

OBJECTIVE

To document the incidence of injury in 6-15 year olds playing rugby union, rugby league, and netball, and to identify the common mechanisms, sites, severity, and time of injury.

METHODS

Cross sectional data were collected by trained observers who watched 258 games of rugby union, netball, and rugby league over a four week period. The condition of the injured participants was monitored until recovery.

RESULTS

In total, 5174 players were observed and an injury rate of 18 per 1000 player hours was calculated. Of all observed injuries, 29% required some form of medical treatment. A significant difference (p<0.05) in the distribution of injury over the four quarters of the games was recorded, most occurring in the first three quarters. In total, 81% of the injuries were classified as contact injuries, and these mainly occurred through direct contact with the opposition. Of all observed injuries, 27% were recurrent.

CONCLUSIONS

The incidence of injury in rugby union, netball, and rugby league is low for children aged between 6 and 15 years relative to adult rates.

Character and duration of pharmacological effects of intravenous isoxsuprine

Isoxsuprine is a therapeutic medication used to treat navicular disease and other lower limb problems in horses and is one of the more frequently detected therapeutic agents in racing horses. In a crossover study, horses were administered isoxsuprine i.v. to determine the character and duration of its pharmacological effects. Isoxsuprine significantly increased heart rate 5-150 min following injection. Unrestrained activity following isoxsuprine treatment was significantly greater than control activity for 105 min after treatment. There was an apparent, although statistically nonsignificant, increased cutaneous blood flow resulting in visible water vapour and sweat production 5-60 min after administration. Initially, there was no difference in skin temperature between control and isoxsuprine treatment values; however, skin temperature decreased below control values 45-120 min after injection. Concurrently, there was a significant decrease in rectal temperature reflecting a decrease in body core temperature. Using infrared thermography, a significant decrease in superficial skin temperature of the front legs occurred 30-240 min after treatment. Isoxsuprine also reduced smooth muscle tone, which was apparent by decreased tone of the internal anal sphincter 10-180 min after treatment. It was concluded that the measurable pharmacological effects of i.v. isoxsuprine are short lived, since none of the above responses were apparent 4 h or more after i.v. administration.

Quadriceps muscle training in a restricted range of motion: implications for anterior cruciate ligament deficiency

This study examined the transferability of strength gains associated with training in a limited range of motion, and at a specific joint angular velocity, to a different part of the range of motion. Work was assessed in control (N = 14) and experimental (N = 14) groups that performed baseline tests on a Kin-Com dynamometer at 1.05, 2.09, and 3.14 rad/sec, over a range of motion from 90 degrees flexion to full extension. The experimental group then underwent training consisting of three sets of eight maximum-effort knee extensions on a Kin-Com dynamometer at a joint angular velocity of 2.09 rad/sec, three times per week for 8 weeks. The range of motion at which they trained was 90 degrees to 45 degrees. After training, baseline tests were repeated in both groups. The findings showed that the work done by the quadriceps muscles of the experimental group increased significantly (p < .05) in the training range of motion across all joint angular velocities. In the untrained range of motion, the work done by the experimental group increased significantly (p < .05) only at the training angular velocity of 2.09 rad/sec. These findings provide evidence that training in a range of motion in which anterior shear forces are low can lead to changes in strength in the range of motion in which anterior shear forces are high. Hence, such exercise is of potential benefit to the anterior cruciate ligament-deficient individual.

Surfactant content in children with inflammatory lung disease

OBJECTIVE

To determine surfactant profiles of tracheal secretions in mechanically ventilated children with respiratory failure secondary to bacterial pneumonia, viral pneumonitis, adult respiratory distress syndrome (ARDS), and cardiopulmonary bypass.

DESIGN

Prospective, cohort study.

SETTING

Tertiary, multidisciplinary, pediatric intensive care unit.

PATIENTS

One hundred twenty pediatric patients with respiratory failure requiring mechanical ventilation.

INTERVENTIONS

Routine tracheal aspirates were collected from children with bacterial pneumonia, viral pneumonitis, ARDS, postcardiopulmonary bypass, and a postsurgical control group. Samples were obtained on days 1, 2, 3, after every week of intubation and on the day of extubation.

MEASUREMENTS AND MAIN RESULTS

The tracheal aspirates were analyzed by high-performance liquid chromatography for lecithin/sphingomyelin rations and by enzyme-linked immunosorbent assay for surfactant proteins A and B. Lung compliance and the oxygenation index were measured on each day of sample collection. On day 1, patients with bacterial pneumonia, viral pneumonitis, and ARDS had decreased lecithin/sphingomyelin ration (p < .001), and those patients with bacterial pneumonia and viral pneumonitis had decreased surfactant protein A/protein concentration (p < .001). The lecithin/sphingomyelin ratios and surfactant protein A/protein concentration were significantly different among the groups (p < .001), with the bacterial pneumonia and viral pneumonitis groups having higher lecithin/sphingomyelin ratios and increased surfactant protein concentrations before extubation. Pulmonary compliance was lower and the oxygenation index was higher than controls (p < .001) in patients with bacterial pneumonia, viral pneumonitis, and ARDS. Pulmonary compliance was correlated weakly with lecithin/sphingomyelin ratio (r2 = .11, p < .001) and surfactant protein A/protein concentration (r2 = .03, p < .05). Surfactant protein B was similar in the diagnostic groups. Surfactant content in tracheal secretions from cardiopulmonary bypass patients was equivalent to controls.

CONCLUSION

Abnormal tracheal aspirate surfactant phospholipids and surfactant protein A were noted in children with bacterial pneumonia, viral pneumonitis, and ARDS, but not in children on cardiopulmonary bypass.

Calcitonin is a physiological inhibitor of prolactin secretion in ovariectomized female rats

Calcitonin (CT) inhibits secretion of PRL when administered intravenously in rats and humans. It also inhibits PRL release from cultured rat anterior pituitary (AP) cells. Recent evidence suggests that CT-like immunoreactive peptide is synthesized and released from the AP gland. However, its physiological role in the regulation of PRL secretion has not been understood. Present studies tested the role of endogenous pituitary CT (pit-CT) in the regulation of PRL secretion in vivo by passive immunization. In the first group of experiments, ovariectomized (ovx) adult female rats were administered either preimmune or anti-salmon CT (sCT) serum, and their serum PRL levels were analyzed at various time points up to 3 h. A second group of experiments examined the effects of anti-sCT serum and dopamine on PRL release from cultured rate AP cells. In the next group of experiments, the regional distribution of pit-CT secretion was examined in different sections of the AP gland. In the last set, CT-like activity of AP extract was tested in neonatal rat kidney cells, which respond to CT with an increase in cAMP accumulation. These experiments also tested whether anti-sCT serum reduces AP extract-induced increase in cAMP accumulation. The results suggest that anti-sCT serum dramatically increased serum PRL levels (by 5-fold) of ovx rats within 30 min of administration. The serum PRL levels declined gradually after the peak. However, a significant increase in serum PRL levels was maintained by the anti-sCT serum for the duration of the experiment. The anti-serum also induced a significant increase in PRL release from cultured AP cells when added to the presence or absence of dopamine. The distribution profile of pit-CT within the AP gland suggests that the release of pit-CT immunoreactivity was significantly greater in the inner sections, and anti-sCT serum also caused greater increase in PRL release in these sections. Finally, AP extract and sCT stimulated cAMP accumulation in neonatal rat kidney cells, and anti-sCT serum significantly reduced AP extract-induced cAMP accumulation. These results demonstrate that pit-CT is an important regulator of tonic PRL secretion in female rats and can potently inhibit PRL secretion even in the presence of dopamine.

Immunopathogenic mechanisms of HIV infection

A complex array of multiphasic and multifactorial immunopathogenic mechanisms are involved in the establishment and progression of human immunodeficiency virus (HIV) disease. After primary infection, acute viremia occurs with wide dissemination of HIV. During this early viremic phase, the virus is trapped within the processes of follicular dendritic cells in the germinal centers of lymphoid tissue. Also, during this phase of primary infection, some patients show major expansions of certain subsets of CD8+ T cells that are identified by the expression of a particular variable region of the beta chain of the T-cell receptor. These expansions are manifestations of responses to HIV that may be important in controlling the progression of HIV infection. In addition, inappropriate immune activation and elevated secretion of certain proinflammatory cytokines occur during HIV infection; these cytokines play a role in the regulation of HIV expression in the tissues. Infection of progenitor cells in bone marrow and the thymus contribute to the lack of regeneration of immunocompetent cells. Dendritic cells are involved in the initiation and propagation of HIV infection in CD4+ T cells. In studies of long-term nonprogressors - persons who have stable CD4+ T-cell counts and no HIV disease progression despite years of HIV infection - preserved lymph node architecture, low viral burden, and viral expression were found.

Regulatory significance of procaine residues in plasma and urine samples: preliminary communication

Plasma and urinary concentrations of procaine and the duration of response to procaine after its administration as a local anaesthetic to horses were studied. Following injection of a clinical dose of procaine HCl (80 mg), the concentration of procaine in plasma was less than the lower limit of quantitation and unsuitable for threshold determination. Therefore, the urinary concentration of procaine was determined after injection of a dose of 5 mg procaine HCl, the highest no-effect dose (HNED) of this agent. Free unconjugated procaine in equine urine reached a peak concentration of 23.7 ng/mL, while total (unconjugated plus conjugated) procaine peaked at 37.9 ng/mL (mean urine pH of 8.5). Because a basic drug may concentrate substantially in acidic urine, a threshold concentration of 25 ng/mL of unconjugated procaine is a reasonable and conservative threshold for procaine at this time. Horses were administered abaxial sesamoid blocks containing 2% procaine HCl (40, 80, 160 and 320 mg) and 2% procaine HCl (40 and 320 mg) with epinephrine (1:100,000) in local anaesthetic experiments. There was a significant local anaesthetic (LA) effect for all doses of procaine HCl with the duration of effect ranging from 30 min (40 mg) to 60 min (320 mg). The addition of epinephrine significantly increased the duration of local anaesthesia to 180 min for a 40 mg dose and 420 min for a 320 mg dose. Because epinephrine may extend the duration of local anaesthesia beyond a reasonable period of confinement for horses before the starting time of a race, the increased LA effect following the addition of epinephrine to procaine has regulatory significance.

Determination of highest no effect dose (HNED) for local anaesthetic responses to procaine, cocaine, bupivacaine and benzocaine

The highest no effect doses (HNEDs) for the local anaesthetic (LA) effects of procaine, cocaine, bupivacaine and benzocaine were determined using the heat lamp/hoof withdrawal model of Kamerling et al. (1985b) and the abaxial sesamoid block model of local anaesthesia. The heat lamp rapidly (4 or 5 s) increased the temperature of the superficial skin layers of the pastern to about 90 degrees C, at which point the animal sharply withdrew its hoof. Effective LA blockade precluded this response and superficial skin temperatures exceeded 120 degrees C. Thermal stimulus experiments were routinely terminated after 10 s of exposure to prevent undue tissue damage. Following abaxial sesamoid block with bupivacaine, the HNED for that drug was about 0.25 mg/site. Increasing the dose to 2 mg/site apparently produced complete and prolonged LA blockade. Analogous work showed that the HNED for procaine was about 2.5 mg/site. Similarly, the dose response curve for procaine was parallel with that of bupivacaine but was shifted 10-fold to the right. The duration of the LA response following procaine injection was less than for bupivacaine with the statistically significant response following 40 mg/site injection lasting less than 45 min. Cocaine was less potent than procaine, showing a shallower dose response curve. The HNED for cocaine was less than 5 mg/site, although at this dose the duration of action was extremely short (< 7.5 min). Benzocaine had no significant LA action when a dose of 800 mg was applied topically as a 5% preparation. These results show that the HNEDs for bupivacaine and procaine are remarkably low, that cocaine is somewhat less potent as a LA than might be expected, and that 5% topical benzocaine has no significant pharmacology. The small doses of bupivacaine and procaine producing effective local anaesthesia suggests that developing plasma thresholds for these agents is likely to be very challenging.

Peptide-specific antibodies as probes of the topography of the voltage-gated channel in the mitochondrial outer membrane of Neurospora crassa

The voltage-dependent anion-selective channel (VDAC) in mitochondrial outer membranes is formed by a polypeptide (M(r) 31,000) coded by a nuclear gene whose cDNA sequence is known for several organisms. Antibodies have been raised against synthetic peptides corresponding to four different regions in the predicted sequence of the VDAC polypeptide of the fungus Neurospora crassa (residues 1-20, amino terminus; 195-210, 251-268, and 272-283, carboxyl terminus). Specificity of the antibodies has been characterized in terms of binding to peptides or fungal mitochondria on microtiter plates and binding to mitochondrial proteins of several species in Western blots. Reactivity of three of the four antibodies with fungal mitochondria in suspension increases with lysis of outer membranes, indicating that the respective epitopes (including those near the amino and carboxyl termini) are exposed on the surface of the outer membrane that faces inside the mitochondrion. Preincubation of mitochondria with a polyanion that modulates VDAC voltage dependence strongly inhibits binding of the antibody against residues 251-268, whose epitopes are on the outer mitochondrial surface.

Immunoassay detection of drugs in racing horses: detection of ethacrynic acid and bumetanide in equine urine by ELISA

We have raised antibodies and developed one-step enzyme-linked immunosorbent assays (ELISA) for the diuretics ethacrynic acid and bumetanide as part of a panel of pre- and post-race tests for high potency drugs in racing horses. These ELISA tests are rapid (completed within one hour), sensitive, and can be read by eye. The ELISA detects ethacrynic acid at a drug concentration for half-maximal inhibition (I-50) of about 2.5 ng/mL for the parent drug. After dosing horses intravenously with 5 mg ethacrynic acid per horse, the parent drug or its metabolites are detectable in urine for at least 8 hours. The bumetanide ELISA has an I-50 for the parent drug of about 2.0 ng/mL and will detect bumetanide or its metabolites for about 8 hours in urine after intravenous administration of a 1.7-mg dose per horse. Both antibodies are relatively specific for each drug and do not cross-react with other commonly used diuretics or other acidic compounds often found in post-race equine urine samples. Ethacrynic acid and bumetanide are potent diuretics suspected of being illegally substituted for furosemide in certain racing jurisdictions. Development of these rapid, sensitive, and simple tests for these agents will allow more effective pre- and post-race control of the use of these agents in racing horses. Both tests have recently uncovered several "positives" for these medications in a midwestern racing jurisdiction.

Developing educational programmes for nurses that meet today's addiction challenges

Since undergraduate curricula have in the past offered little substance abuse content, bold and innovative educational programmes are necessary to prepare nurses for the addiction challenges of the 1990s. The University of Kansas and the American Nurses' Foundation (ANF) recently addressed the problem when they were jointly funded by the John W. and Effie E. Speas Memorial Trust to present an alcohol and other drug education project targeted to nurses practicing in the local community. 60 nurses in key clinical settings were given an opportunity to receive general information about substance abuse through two, 2-day workshops. The purposes of the project were; (1) to plan and develop materials for an alcohol and other drug abuse (AODA) curriculum for practicing nurses in a variety of clinical areas; (2) to assess the effectiveness of the programme through on-site and post-workshop participant evaluations; (3) and to refine the curriculum and materials according to evaluation data. Results indicated that participants' knowledge of AODA was significantly increased by the workshop. Attitudes also changed in two areas, permissiveness and belief in treatment interventions. Decreased permissiveness toward substance abuse persisted 3 months after the workshop indicating this may be a lasting change. The conclusion is that education can lead to a change in knowledge and attitudes toward substance abuse.