Pharmacokinetics of lithium in the dog

The pharmacokinetics of lithium were determined in eight adult dogs. The data were fitted to a two-compartment model. Single intravenous doses of lithium chloride, and single oral doses of lithium carbonate were used. The mean plasma lithium half-life (t1/2) following the single intravenous dose was 21.6 h, and the mean apparent specific volume of distribution of the central compartment (V'c) was 0.189 l/kg. Mean bioavailability was 78.8% following oral administration.

Atypical ocular bobbing in acute organophosphate poisoning

Atypical ocular bobbing resulted from an intentional poisoning from dimpylate (Diazinon), an organophosphate compound. In discussing the possible foci and mechanism for atypical ocular bobbing associated with acute organophosphate poisoning, we suggest acetylcholine as a neurotransmitter substance within the ocular motor pathway. A literature review has not shown any previous reported cases with this sign.

Liver autophagy in the influenza B virus model of Reye's syndrome in mice

Biochemical evidence is presented for the autophagic destruction of liver mitochondria in the influenza B virus model of Reye's syndrome in mice. Separation of lysosomes and autophagic vacuoles from mitochondria was accomplished by prior treatment of the mice with Triton WR-1339, resulting in uptake of detergent by these organelles (tritosomes), reducing their densities. The organelles were banded in a discontinuous sucrose gradient. Total protein in the heavy tritosomal fraction increased from 1-2% in controls to 7-8% in virus-treated animals. Ornithine carbamoyl transferase (OCTase), a mitochondrial marker, increased from 2-3% (controls) to 11-15% (virus-treated), and glucose-6-phosphatase, a marker for endoplasmic reticulum, increased from 1-2% (controls) to 8-10% (virus-treated). beta-Galactosidase, a soluble enzyme in the lysosome, and OCTase also increase in the cell extract fraction following virus treatment, indicating that there was turnover of heavy lysosomal contents.

Mouse influenza B virus model of Reye's syndrome. Encephalopathy and microvesicular fatty metamorphosis of the liver by influenza B virus following intravenous administration in mice

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Influenza B virus model of Reye's syndrome in mice: the effect of aspirin

Aspirin is a possible cofactor with influenza B virus in Reye's syndrome. In an attempt to determine whether single or multiple doses of acetylsalicylic acid (ASA) alter mortality in an influenza B virus mouse model of Reye's syndrome, either ASA (300 to 667 mg/kg) or saline was given intraperitoneally to 3-week-old Balb/c mice. Two hours later, one median lethal dose (LD50) of influenza B/Lee virus was given intravenously. Mortality was not significantly increased by the single ASA dose. Blood ASA levels rose as high as 68 mg/dl. The average ASA blood levels in mice 12 hours after receiving the virus plus 667 mg/kg ASA was 22.6 mg/dl, which was significantly higher than the 3.4 mg/dl for mice who received saline plus ASA. No significant increase in mortality occurred in mice given 67 mg/kg ASA twice daily for 7 days and one LD50 dose of virus on day 4. We conclude that a single dose of ASA at up to half the median lethal dose or multiple doses of ASA do not significantly increase mortality in this influenza virus model of Reye's syndrome. However, influenza B virus infection appears to interfere with ASA metabolism.

Respiratory epithelial cells masquerading as agents of primary amebic meningoencephalitis: distinguishing features

CSF does not normally contain motile cells within flagella or cilia. When motile cells are seen in the CSF, they may be incorrectly assumed to be amebae. We studied a patient with a traumatic mucocele, in whom motile ciliated respiratory epithelial cells were seen in the CSF and within a frontal lobe brain abscess.

Preparation and characterization of antibodies with specificity for the amino-terminal tetrapeptide sequence of the platelet-derived connective tissue activating peptide-III

Antisera selectively reactive with the N-terminal tetrapeptide sequence of the platelet-derived connective tissue activating peptide-III mitogen were prepared and characterized. Solid phase synthesized Z-Asn-Leu-Ala-Lys(Z)-OH tetrapeptide representing the N-terminus of the mitogen was used as an immunogen after carbodiimide mediated coupling to methylated bovine serum albumin carrier and subsequent removal of Z groups. Anti-tetrapeptide sera demonstrated cross-reactivity to the mitogen but not beta-thromboglobulin, fibroblast growth factor, or epidermal growth factor, and a limited cross-reactivity to parathyroid hormone. The studies indicate that the N-terminal sequence of the mitogen is accessible for binding with antibody and the antitetrapeptide sera provide a reagent for the selective measurement of biologically active mitogen in the presence of structurally similar beta-thrombo-globulin. In addition, computer analysis of amino acid sequences revealed that few proteins contain the Asn-Leu-Ala-Lys sequence and of those that do, many are retroviral proteins or transforming polyproteins.

Neuropathology of ornithine carbamyl transferase deficiency

Neuropathologic findings in two cases of ornithine carbamyl transferase (OCT) deficiency are presented. In one, a boy 3 days old, the only abnormality related to the enzyme defect was metabolic gliosis which was unusual in distribution being present mainly in the brain stem. In the other case, a girl who died at the age of 2 3/12 years, the brain showed metabolic gliosis in typical location, widespread ulegyria, and moderate atrophy of the internal granular layer in the cerebellum accompanied by development of expansions of Purkinje cell dendrites. Case 2 demonstrates how rapidly changes previously demonstrated in the cerebral cortex after a few months of illness can proceed to massive hemispheric destruction. By now ulegyria has been observed in several disorders of the urea cycle.

Drugs and the liver

The authors discuss the liver's influence on drug disposition in the body and the influence of drugs on the liver. Drug-induced hepatotoxicity with regard to mechanisms and causative agents is discussed, as well as administration of drugs to patients with existing liver disease.

Inner ear anomalies in Waardenburg's syndrome associated with Hirschsprung's disease

Congenital inner ear anomalies are reported in temporal bones of a 22-month-old boy with Waardenburg's syndrome and Hirschsprung's disease. Although no changes in the central auditory pathway were identified, peripheral lesions of the cochlear and vestibular membranous labyrinth were observed. Bilateral atrophy of the organ of Corti and stria, and a sparsity of spiral ganglion cells were observed in the cochlea. Degeneration of the vestibular end organs, including a loss of Scarpa's ganglion cells, was also seen. This is the first report of temporal bone histopathology associated with Waardenburg's syndrome and Hirschsprung's disease. The pathoembryology of these inner ear anomalies associated with aganglionosis of the colon supports the hypothesis that Waardenburg's syndrome and Hirschsprung's disease are hereditary defects of neural crest cells.

Efficacy of ethylenediamine dihydriodide in the prevention of naturally occurring foot rot in cattle

The efficacy of an ethylenediamine dihydriodide containing salt mixture was evaluated with regard to the prevention of naturally occurring foot rot in pastured cattle. Ninety-six cattle were assigned to the treatment group and 96 were assigned to the control group. The groups were allowed consumption of salt-mineral mixtures, ad libitum, that were identical, except with respect to iodine concentration. The control group's mixture contained 0.0025% iodine and the treatment group's mixture contained 0.125% iodine (0.156% ethylenediamine dihydriodide). The incidence of foot rot was measured, as was the severity of the lesions and accompanying lameness. The incidence of foot rot in the control group (20.8%) was significantly (P less than 0.05) greater than the incidence in the treatment group (8.3%). The severity of foot rot was greater (P = 0.024) in the control calves vs the treatment calves. Total serum iodine concentrations were measured in the 2 groups on days 0, 46, and 130 of the experiment. The serum iodine values of the treatment group on day 46 (46 +/- 19.8 g/dl) and day 130 (23 +/- 12.3 g/dl) were significantly different (P less than 0.01) than the serum iodine concentrations of the control animals and the pretreatment values (day 0) of both groups. Production was measured via calf weaning weights. There were no detectable differences between the 205-day adjusted weaning weights of the calves in the control group vs the calves in the treatment group. Clinical signs of iodism were not observed in the cattle involved in this study.

Antisera specificities to 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide adducts of proteins

Animals were immunized with either 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI)-coupled peptide hapten-protein carrier conjugates or with N-acylurea EDCI derived protein carrier. Sera from all animals demonstrated antibody to N-acylurea EDCI when tested by double immunodiffusion using N-acylurea EDCI coupled to a heterologous carrier. Two rabbit antisera, one produced to EDCI-coupled peptide-24-thyroglobulin and another produced to N-acylurea EDCI derived thyroglobulin were further characterized using an enzyme-linked immunosorbent assay (ELISA). Competitive binding assays using either EDCI-coupled peptide-protein conjugates or N-acylurea EDCI derived proteins demonstrated the presence of N-acylurea EDCI reactive antibodies. Such antibodies were also shown to react with the EDCI isourea employed as inhibitor. The specificity of the anti-EDCI antibodies to portions of the EDCI molecule was demonstrated using structural analogues of EDCI. Both 3-dimethylaminopropylamine and 2-dimethylaminoethanol effectively inhibited anti-N-acylurea EDCI reactivity. These results show that when EDCI is used as a coupling agent, antibody is produced to N-acylurea EDCI-carrier, the antibody being primarily directed to the 3-dimethylaminopropyl end of the EDCI molecule.

Cisplatin neuropathy. Clinical, electrophysiologic, morphologic, and toxicologic studies

Ten of 11 patients with ovarian cancer receiving cisplatin developed a distal sensory neuropathy, manifested early by decreased vibratory sensibility in toes and depressed ankle jerks and later by uncomfortable paresthesias. Eleven patients receiving cisplatin, 50 mg/m2 monthly (mean total, 580 mg/m2) were studied prospectively with monthly neurologic examinations and conduction velocity determinations of median, peroneal, and sural nerves. Early signs were decreased vibratory sensibility in toes (mean dose, 417 +/- 132 mg/m2 [SD]) and loss of ankle jerks (mean dose, 455 +/- 86 mg/m2). With continued therapy, four developed paresthesias. Strength was unaffected. Sural nerve responses abruptly disappeared in six of peripheral nerves from four patients showed axonal degeneration and secondary myelin breakdown. Platinum concentrations in three patients were similar in tumor (3.3 micrograms/g), sural nerves (3.5 micrograms/g), and spinal ganglia (3.8 micrograms/g), but lower in brain (0.17 microgram/g). This may explain the cisplatin toxicity of peripheral nerves with relative sparing of the central nervous system.

Use of dextran and post-primary antibody fixation in immunoperoxidase staining of fresh frozen tissue. Detection of immunoglobulin associated with squamous carcinomas of the head and neck

Use of unfixed fresh frozen tissue sections for immunocytochemical studies reduces the possibility of denaturation of antigenic determinants compared to formalin fixation and paraffin embedding procedures. However, tissue and cellular morphology can be extensively altered in the numerous application and washing steps with frozen tissue sections. We tested a number of buffer solutions and showed that the use of dextran-containing buffers and fixation by glutaraldehyde after primary antibody application preserves tissue morphology. The procedures described here are also applicable to ascertaining the presence of Fc receptors of leukocytes in sections of carcinoma tissues. The buffered dextran washes and post-primary antibody fixation method was used to demonstrate the presence of immunoglobulin associated with squamous carcinoma cells. The immunoglobulin was not removed by washing of tissue sections at 37 degrees C but could be removed by low or high pH buffer washes, suggesting that the immunoglobulin is bound in a specific manner.

Efficacy of ethylenediamine dihydriodide as an agent to prevent experimentally induced bovine foot rot

Ethylenediamine dihydriodide (EDDI) was administered by capsule and as a feed premix to cattle in 2 studies. In study I (32 steers), EDDI was given at 0, 12.5, 50, and 200 mg/animal each day and in study II (36 steers) at 0, 30, and 200 mg/animal each day. Serum iodine levels were monitored during the studies. The cattle were inoculated intradermally in the interdigital space with a mixture of Fusobacterium necrophorum and Bacteroides melaninogenicus to induce acute foot rot at day 15 (study I) or day 28 (study II) after EDDI administration was started. Lesions and lameness were evaluated 5 days after challenge exposure, using a subjective scoring system. The cattle receiving EDDI had significantly less severe lesions and lameness than control cattle in both studies (study I, P less than 0.003; study II, P less than 0.001). The results indicated that EDDI was efficacious in prevention of foot rot. The studies demonstrated a direct relationship between dosage levels of EDDI and serum iodine levels. However, at the large dosage level (200 mg) there were some individuals that showed an inability to metabolize and excrete the iodine as demonstrated by high serum iodine levels (600 to 700 micrograms of iodine/dl of serum).

Halothane-sparing effect of xylazine in dogs and subsequent reversal with tolazoline

Halothane MAC (the minimum alveolar concentration of halothane to produce anaesthesia in 50% of the animals tested) was determined to be 0.92 +/- 0.16 volumes % in eight English Pointer dogs. Alterations in halothane MAC induced by an intravenous bolus of xylazine (1.1 mg/kg) and then tolazoline (5 mg/kg) was determined in each dog following control (halothane MAC) measurement. Following xylazine administration, MAC significantly decreased to 0.57 +/- 0.023%. Immediately following determination of the xylazine-halothane MAC value in each dog, tolazoline was administered and the halothane requirement (MAC) was again assessed. Halothane MAC significantly increased to 1.24 +/- 0.036%. Tolazoline administration induced immediate arousal in the xylazine-halothane anaesthetized dogs requiring a rapid increase in halothane concentration to maintain anaesthesia. Thus, the administration of tolazoline, an alpha adrenergic antagonist, following xylazine administration significantly increased the anaesthetic requirement (MAC) of halothane. Xylazine, an alpha 2 adrenergic agonist, decreased halothane anaesthetic requirement (MAC) in the eight dogs studied. These results are consistent with the hypotheses that stimulation of central alpha 2 receptors is the mechanism by which xylazine produces sedation and that inhibition of CNS excitatory neurotransmitter release decreases halothane anaesthetic requirement.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperglycemia and hypoinsulinemia during xylazine-ketamine anesthesia in Thoroughbred horses

Plasma glucose and serum insulin concentrations in Thoroughbreds administered xylazine hydrochloride (1.1 mg/kg; IV) and ketamine hydrochloride (2.2 mg/kg; IV) at dosages sufficient to induce short periods of recumbency and anesthesia were measured. Samples of blood were collected from 6 adult horses before, during, and after the anesthetic period. Plasma glucose (mg/dl) was significantly increased above control (-30 minute concentration) from 15 to 150 minutes after xylazine administration with the peak value occurring at 30 minutes. Serum insulin (microU/ml) was significantly decreased from control from 5 to 90 minutes after xylazine administration, with the nadir occurring at 15 minutes. The alterations in plasma glucose and serum insulin concentrations in xylazine-ketamine-anesthetized horses were similar to the changes in xylazine-sedated horses.

Pharmacokinetics of chloramphenicol in non-lactating cattle

The pharmacokinetics and bioavailability of a formulation of chloramphenicol base in propylene glycol were determined following administration of single intravenous (i.v.) and subcutaneous (s.c.) 50 mg/kg doses of chloramphenicol to six non-lactating Holstein cows. Mean serum concentrations of chloramphenicol following i.v. administration of 50 mg/kg declined rapidly from a peak of greater than 100 micrograms/ml to 6.9 micrograms/ml at 12 h after administration. Serum concentrations were not detectable at 24 h after administration. The curve of serum concentrations vs time was characteristic of a two-compartment open model. Mean i.v. data gave a biological half-life of 4.3 h and a volume of distribution of the central compartment of 0.44 l/kg. Serum concentrations of chloramphenicol following s.c. administration of 50 mg/kg rose slowly to a broad peak near 20 micrograms/ml from 3 to 8 h after administration and then declined. These data were also analysed according to a two-compartment open model. The biological half-life was 4.2 h and the volume of distribution of the central compartment was 0.50 l/kg. Significant adverse reactions, including acute collapse, intravascular haemolysis and haemoglobinuria, were observed in cows when dosed i.v. Cows dosed s.c. exhibited local reactions at injection sites. The disadvantages of administration of 50 mg/kg doses of chloramphenicol base in propylene glycol appear to be significant and may outweight the potential advantages of parenteral use of the drug as presently formulated.

Inner ear pathology associated with Reye's syndrome

Severe pathological changes were observed in the inner ear tissues of a 2-month-old patient who died of Reye's syndrome after 5 days of hospitalization. In the organ of Corti, the inner hair cells appeared to be more severely damaged than the outer hair cells. Various degrees of degeneration were observed in all non-sensory epithelial cells lining the cochlear duct. In most turns of the cochlear duct, Reissner's membrane was ruptured and/or collapsed onto the organ of Corti. Likewise, both sensory and non-sensory cells of the vestibular end organs were markedly degenerated. These observations suggest that the inner ear tissues are acutely affected in patients with Reye's syndrome, and that the changes may cause impairment of hearing and/or equilibrium in patients who recover.

Factors influencing survival and morbidity with very low birth weight delivery

Factors influencing survival and morbidity in a group of 214 consecutively delivered very low birth weight infants (500 to 1500 g) are examined. The perinatal mortality was 313 per 1000 births. Of 185 live-born, congenitally normal infants, 133 (72%) were discharged alive. Respiratory distress syndrome was the most common form of significant morbidity, occurring in 114 infants (62%). Intraventricular hemorrhage was diagnosed in 38 (21%) of the infants. Neither survival nor morbidity was influenced by the mode of delivery. The current trend of a liberalized policy of cesarean section for the very low birth weight delivery is questioned.

Pharmacokinetic studies of theophylline in cats

The pharmacokinetics of theophylline were determined in adult cats and the data were fitted to a two-compartment model. Single intravenous and multiple oral doses of aminophylline were used. The mean plasma theophylline half-life (t1/2) following the single intravenous dose was 7.8 h and the mean apparent specific volume of distribution (V'd(area] was 0.46 1/kg. The absorption half-life (t1/2ab) was 0.5 h and the bioavailability was 96% following oral administration. There was excellent agreement between the predicted and observed plasma theophylline concentrations following multiple oral doses.

Disposition of gentamicin in the genital tract of cows

The distribution of gentamicin (G) in plasma and uterine lumen was studied following intramuscular (i.m.) and intrauterine (i.u.) treatment. A Foley catheter was inserted into one uterine horn and retained in place by inflation of the cuff. This provided a closed system for collection of uterine lumen samples and analysis of the concentration of gentamicin for 6 h following treatment. Four normal cycling and healthy cows in dioestrus were given i.m. injections of 4 mg gentamicin/kg BW and another two were given i.m. injections of 2 mg gentamicin/kg BW gentamicin. The uteri were infused with 50 ml saline containing phenolsulphonphthalein (PSP) indicator. Blood and infused solution (IS) samples were periodically collected during the 6-h period following i.m. administration. Six hours after injection, approximately 183.7 micrograms gentamicin and 39.4 micrograms gentamicin were accumulated in the uterine lumen of cows receiving 4 mg gentamicin/kg BW and 2 mg gentamicin/kg BW, respectively. The amount of gentamicin reaching the blood stream after i.m. administration of 4 mg gentamicin/kg BW was 2.89 times that reached after administration of 2 mg gentamicin/kg BW based on the area under the curve of plots of plasma concentration of gentamicin versus time. Four normal-cycling and healthy cows in dioestrus were given i.u. infusions of gentamicin (225-275 mg) diluted in 50 ml saline containing PSP indicator using a Foley catheter in a closed system. Samples from the IS and blood were collected at various intervals for 6 h after infusion. Following i.u. infusion of gentamicin, an average of 29.4% of the dose was absorbed into the bloodstream. The majority of the dose of gentamicin (70.6%) remained in the uterine lumen throughout the 6-h period.

Isolation of Trichomonas vaginalis from the respiratory tract of infants with respiratory disease

Trichomonas vaginalis was isolated from the respiratory tracts of two infants with respiratory disease. Bacterial and viral cultures of tracheal aspirates and nasopharyngeal specimens did not detect bacterial pathogens or viruses; however, T vaginalis was found to be present in inoculated cell cultures. Both infants were delivered vaginally by mothers with known previous episodes of T vaginalis infection. The possibility that this organism may, on occasion, cause respiratory tract disease needs further evaluation.

Determination of lidocaine concentrations producing therapeutic and toxic effects in dogs

Lidocaine was infused at a fixed zero-order rate to eight healthy mongrel dogs until tonic extension (n = 5) and cortical seizures (n = 7) were produced. Lidocaine concentrations determined at 5-min intervals were used to calculate concentrations at which these effects occurred. The tonic extension phase occurred at a mean lidocaine concentration of 8.21 +/- 1.69 micrograms/ml. After a 1-month rest period, the same dogs were anaesthetized and ventricular tachycardia was produced by administering ouabain. Lidocaine was again infused at a fixed zero-order rate until all beats of ventricular origin were abolished. This occurred at a mean lidocaine concentration of 6.25 +/- 1.49 micrograms/ml.

Pharmacokinetics of digoxin in cattle

Digoxin was administered as a single intravenous injection of 22 micrograms/kg to six cattle. The resulting serum concentrations were fitted by both a bi- and tri-exponential equation with the latter providing the best fit to the data of a majority of the animals. The biological half-life of digoxin in cattle was found to be 7.8 h. This relatively short half-life in comparison to other animal species dictates that digoxin should be administered more frequently to cattle to provide therapeutic concentrations in serum without broad fluctuations in serum concentrations. Computer simulations of various intravenous dosage regimens suggested that a loading dose of 22 micrograms/kg followed by an infusion of 0.86 micrograms/kg/h would offer the greatest safety and efficacy in bovine patients.

Distribution of oxytetracycline in genital tract tissues of postpartum cows given the drug by intravenous and intrauterine routes

Oxytetracycline (OTC) was administered by constant IV infusion to 3 healthy postpartum cows at rates predicted to approach a steady-state plasma concentration of 5 micrograms/ml. After 8 hours of constant IV infusion, genital tissues were surgically removed. The mean plasma-to-tissue ratios of concentrations of OTC were 0.95, 1.33, 1.88, and 1.04 (2 cows only) for caruncles, endometrium, uterine wall, and ovaries, respectively. Differences between the ratios of any 2 of the uterine tissues were statistically significant (P less than 0.05). Intrauterine (IU) infusions of 5.5 mg of OTC/kg were administered to 3 healthy postpartum cows and 3 postpartum cows with metritis. The mean values of the fraction of the drug absorbed from the uteri of cows given IU infusions of OTC were 0.50 and 0.23 for healthy postpartum cows and postpartum cows with metritis, respectively. Concentrations of OTC were high in the caruncles and endometrium of all cows at 24 hours after IU infusions of the drug. Concentrations in the plasma, uterine wall, and ovaries were low, with mean concentrations of OTC in these tissues in postpartum cows with metritis being lower than those in the same tissues of healthy postpartum cows. Computer-simulated genital tissue concentrations of OTC after twice daily IV doses of 11 mg/kg indicated that this dosage regimen would provide postpartum uterine tissue concentrations greater than 5 micrograms/g throughout the dosage interval in all tissues, except the uterine wall.

Distribution of oxytetracycline in the healthy and diseased postpartum genital tract of cows

Previously determined pharmacokinetic parameters of the disposition of oxytetracycline (OTC) in cows were used to predict an IV priming dose and a rate of constant IV infusion of OTC sufficient to approach steady-state equilibrium of the drug between plasma and genital tissue concentrations in healthy postpartum cows and postpartum cows with endometritis. After 8 hours' constant IV infusion at rates calculated to maintain a plasma concentration of approximately 5 micrograms/ml, the mean concentrations of OTC in plasma (microgram/ml) and tissues (microgram/g) of healthy and infected postpartum cows, respectively, were: plasma, 4.95 and 5.23; uterine tissue, 3.65 and 4.18; and ovarian tissue, 4.57 and 4.53. The mean plasma to genital tissue ratios for healthy and infected postpartum cows, respectively, were 1.38 and 1.31 for uterine tissue and 1.09 and 1.16 for ovarian tissue. There were no significant differences (P greater than 0.28) between healthy and infected postpartum cows in any of the parameters investigated. However, plasma-to-genital tissue ratios of concentrations of OTC in postpartum cows as a group were significantly higher (P less than or equal to 0.03) than those previously determined in cycling cows. Computer-simulated uterine tissue concentrations of OTC, after twice daily IV doses of 11 mg of OTC/kg of body weight, indicated that this dosage regimen would provide postpartum uterine tissue concentrations greater than 5 micrograms/g during most of the dosage interval.

Pharmacokinetics of lidocaine and its active metabolites in dogs

The pharmacokinetics of lidocaine in dogs were investigated following the intravenous and intramuscular administration of single doses of lidocaine hydrochloride. The mean elimination rate constant and the mean specific clearance determined for the intravenous portion of the study were 0.786 h-1 and 2.40 1/kg/h, respectively. Following intramuscular administration the mean absorption rate constant was 7.74 h-1. Absorption was nearly complete as the percentage of an intramuscular dose absorbed averaged 91.9%. Concentrations of two N-deethylated metabolites, determined following the administration of lidocaine suggest that monoethylglycinexylidide is eliminated rapidly while glycinexylidide is more slowly eliminated. The relative contribution of these metabolites to the therapeutic and toxic effects of lidocaine and the potential for glycinexylidide accumulation during lidocaine administration remain to be investigated.

Experimental influenza B virus toxicity in mice. A possible model for Reye's syndrome

Mice intravenously injected with concentrated infectious influenza B/Lee/40 virus (LD50 = 6400 hemagglutinin units) developed lethargy, seizures, coma, and death 1 to 3 days later. The cerebrospinal fluid cell count was normal. Serum glutamic oxaloacetic transaminase levels increased 19-fold and plasma ammonia levels elevated 2.6-fold over control values. Serum bilirubin levels remained normal. Microvesicular fatty metamorphosis developed in the liver, whereas the brain showed mild cerebral edema without inflammatory changes. Viral propagation did not occur in liver or brain, but viral hemagglutinin, neuraminidase, and probably nucleoprotein antigens were produced in hepatocytes. Many of the clinical, biochemical, and pathologic features of the mouse illness are similar to those seen in Reye's syndrome.

Relapsing herpes simplex encephalitis following antiviral therapy

Although treatment for herpes simplex virus (HSV) encephalitis with antiviral agents has improved survival, occasional patients experience unexplained clinical exacerbations. This report presents evidence that some relapses may occur from recurrent viral encephalitis. An adult male developed the classic symptoms of HSV encephalitis. The cerebrospinal fluid (CSF), electroencephalogram, and isotope brain scan suggested a localized encephalitis involving the left temporal lobe. The patient was treated for 10 days with high doses of cytosine arabinoside instead of the currently recommended adenine arabinoside. Progression of encephalitis stopped, and clinical recovery occurred. The HSV antibody titer increased eightfold. Fifty-four days after the initial encephalitis, the patient relapsed with a subacute progressive encephalitis involving the same brain area. The CSF demonstrated oligoclonal bands, elevated immunoglobulin G levels (100 mg/dl), and a high HSV antibody titer (1:8,192 by indirect hemagglutination test). From a left temporal lobe biopsy taken 74 days after onset of the initial encephalitis, herpes simplex virus type 1 was isolated. Without renewed antiviral drug therapy, the patient slowly recovered.

Immunological and microbiological studies of midtrimester amniotic fluid

Midtrimester amniotic fluids (MAF) from 73 women undergoing an amniocentesis were studied. The mean immunoglobin G (IgG) level was 34 +/- 14 mg/dl, which is higher than that reported in the third trimester. The maternal serum:MAF IgG ratio was 29 suggesting the blood:MAF barrier is less restrictive than others like the blood:cerebrospinal fluid barrier. Antibodies to herpes simplex virus (HSV) type 1 were detected in 78% of the MAF and the maternal serum:MAF HSV antibody titer ratio was 33. Antibodies to cytomegalovirus (CMV) were found in 84% of the MAF and the maternal serum:MAF CMV antibody titer ration was 40. Whenever either antibody was detected in the maternal serum it was also found in the MAF. No viruses, bacteria, mycoplasma, fungi and chlamyidae were isolated from MAF.

Xylazine hydrochloride-induced hyperglycemia and hypoinsulinemia in thoroughbred horses

The effects of intravenous xylazine (1.1 mg/kg) were studied in six thoroughbred horses (five mares and a stallion). Plasma glucose concentration increased to 168% of control at 45 min and decreased to 112% of control at 180 min. Insulin had decreased to 31% of control at 15 min. Thereafter, insulin concentration increased, reaching its highest concentration at 150 min. The mechanism for these changes is not fully understood and further investigation is indicated.

Effects of chloramphenicol on the development of immune responses to canine distemper virus in beagle pups

The effect of oral chloramphenicol (CHPC) on the development of immune responses to canine distemper virus (CDV) in Beagle pups was studied. Dogs were treated with CHPC for 14 days at a dose of 50 mg/kg, three times a day. Hematologic changes in CHPC-treated dogs included: polychromasia, anisocytosis, and target cell formation of red blood cells concurrent with vacuolation of lymphocytes and basophilic granule formation in neutrophils. Dogs given this therapy showed normal in vivo and in vitro immune responses after CDV vaccination and survived a virulent CDV challenge, whereas untreated, unvaccinated dogs became ill or died after challenge exposure. The results of this study indicate that CHPC therapy does not interfere with either the prechallenge immune response to attenuated viral antigen or the efficient immune mechanisms invoked during virulent virus challenge.

Review of glucocorticoid pharmacology

Rational glucocorticoid therapy depends on a complicated interplay of many factors. An understanding of the physiology of the hypothalamic-pituitary-adrenal axis, the comparative potencies, duration, and adverse effects of the available corticosteroid bases and their esters, and especially the specific goals of the therapy for a wide variety of diseases facilitates this therapy. It is impossible to make specific dose recommendations for glucocorticoid therapy. Individual patients and their various diseases respond differently to a given dose of glucocorticoid.

Distribution of oxytetracycline in the genital tract of cows

Pharmacokinetic parameters of the disposition of oxytetracycline (OTC) were investigated in healthy cycling dairy cows after a single IV dose of 22 mg/kg of body weight. The biological half-life of OTC was 6.5 hours. These data were used to predict an IV priming dose and a rate of constant IV infusion of OTC sufficient to approach steady-state equilibrium of the drug between a plasma concentration of approximately 5 microgram/ml and a uterine tissue concentration. After 8 hours' constant IV infusion, the mean plasma concentration of OTC was 4.86 +/- 0.68 microgram/ml and the mean uterine tissue concentration of OTC was 4.50 +/- 0.45 microgram/ml. The mean ratio of plasma-to-uterine tissue OTC concentrations was 1.08. Computer-stimulated IV multiple doses of OTC at 11 mg/kg every 12 hours and 11 mg/kg every 24 hours suggested that the former dosage regimen could provide uterine tissue concentrations greater than 5 microgram/ml during the dosage interval, whereas the latter could provide such concentrations for only the first 12 hours of a 24-hour dosage interval.

Experimental viral infections of the inner ear. III. Viremic spread of reovirus to hamster eighth nerve ganglion cells

Rubella, cytomegalovirus, mumps, and rubeola viruses cause deafness in man and are believed to reach the inner ear through viremic spread. Although several experimental studies of viral infection of the inner ear have been described, all require the virus inoculum to reach the labyrinth directly rather than through hematogenous spread. In this model, reovirus, type 3, infected the cell bodies of cochlear and vestibular ganglia of infant hamsters following a viremia induced by intraperitoneal inoculation. This model provides the first experimental evidence for viremic spread to the inner ear.

Increased incidence and prevalence of multiple sclerosis in Los Alamos County, New Mexico

The incidence and prevalence of multiple sclerosis (MS) in Los Alamos County, New Mexico, were investigated because the number of reported cases appeared to have increased. The point prevalence on November 1, 1979, was 75.7 per 100,000, and average annual incidence rates for the period 1960-1969 and 1970-1979 were 3.4 and 3.7 per 100,000, respectively. The rates of MS in Los Alamos County were greater than expected from previous epidemiologic surveys of North America. The unusual ethnic composition and high socioeconomic level of the population probably contributed to the increases.

Acute thallium poisoning: toxicological and morphological studies of the nervous system

Nine days following ingestion of 5 to 10 gm of thallium nitrate, a young man died with severe cranial and peripheral neuropathy, anuria, and heart failure. Ultrastructural examination of nerves obtained on days 7 and 9 demonstrated axonal degeneration with secondary myelin loss. Axons were swollen and contained distended mitochondria and vacuoles. Thallium levels in more than twenty organs and body fluids ranged from below 1.0 to 178 microgram/gm; concentrations in twenty areas of the nervous system ranged from 29 to 140 microgram/gm. The highest brain levels of thallium were found in gray matter. In the thalamus, 87% of the thallium was present in cell sap. Tissue concentrations of thallium did not parallel those reported for potassium, suggesting that thallium distribution differs from potassium distribution in human beings.