Catecholamines, cyclic AMP and renin in two contrasting forms of essential hypertension

Essential hypertension (EH) can be subdivided according to the sympathetic and renin activity into two contrasting forms: (1) borderline beta-hyperadrenergic renin hyperresponsive and (2) stable beta-hypoadrenergic renin hyporesponsive EH. These two forms probably represent two expreme poles in the spectrum of EH in which sympathetic and renin hyper- or hyporeactivity cannot be accounted for by catecholamine determinations solely. beta-Adrenergic responsiveness monitored by plasma cyclic AMP determinations revealed plasma cyclic AMP, renin and circulatory hyperresponsiveness to isoproterenol in borderline hyperadrenergic EH while the opposite, cyclic AMP and renin hyporesponsiveness to insulin-induced hypoglycemia have been described in low renin stable EH. The kidney is in the center of the adrenergic abnormality in the two forms of EH with the borderline one excreting into the urine catecholamines not accounted for by their glomerular filtration. Catecholamines solely, however, do not account for the differences in both forms of EH which can probably be attributed to their different beta-adrenergic responsiveness.

Eye-dominance, Writing Hand, and Throwing Hand

Handedness and eye-dominance are undoubtedly associated statistically, although a previous meta-analysis has found that the precise relationship is difficult to explain, with about 35% of right-handers and 57% of left-handers being left eye dominant. Of particular difficulty to genetic or other models is that the proportions are distributed asymmetrically around 50%. The present study asked whether this complicated pattern of association occurred because, following Peters, it is necessary to divide right-and left-handers into consistent handers (who write and throw with the same hand) and inconsistent handers (who write and throw with opposite hands). In an analysis of 10,635 subjects from questionnaire studies, 28.8% of left-handers and 1.6% of right-handers by writing were inconsistent for throwing. Our results also showed that writing hand and throwing hand both relate independently to eyedness, that throwing hand is somewhat more strongly associated with eyedness, and that the awkward asymmetry around 50% is now removed, 24.2% of consistent right-handers being left eye dominant compared with 72.3% of consistent left-handers, and 55.4% of inconsistent right-handers compared with 47.0% of inconsistent left-handers. We conclude that eyedness is phenotypically secondary to writing and throwing handedness. In our discussion we note that eyedness runs in families, we present new data suggesting that writing hand and throwing hand are co-inherited, and we argue that further data are now required to model properly the associations of writing hand, throwing hand, and eyedness, as well as probably also footedness and language dominance.

Pre-clinical evaluation and efficacy studies of a melanin-binding IgM antibody labeled with 188Re against experimental human metastatic melanoma in nude mice

PURPOSE

Currently there is no satisfactory treatment for metastatic melanoma. Radioimmunotherapy (RIT) uses the antigen-antibody interaction to deliver lethal radiation to target cells. Recently we established the feasibility of targeting melanin in tumors with 188-Rhenium ((188)Re)-labeled 6D2 mAb to melanin. Here we carried out pre-clinical development of (188)Re-6D2 to accrue information necessary for a Phase I trial in patients with metastatic melanoma.

RESULTS

TCEP proved to be effective in generating a sufficient number of -SH groups on 6D2 to ensure high radiolabeling yields with (188)Re and preserved its structural integrity. (188)Re-6D2 was quickly cleared from the blood with the half-life of approximately 5 hrs and from the body--with the half-life of 10 hr. The doses of 0.5, 1.0 and 1.5 mCi significantly (p < 0.05) slowed down A2058 tumor growth in nude mice, also causing release of melanin into the extracellular space which could provide additional target for repeated treatments. Transient effects of RIT on WBC and platelet counts resolved by Day 14 post-treatment.

EXPERIMENTAL DESIGN

Tris(2-Carboxyethyl) Phosphine Hydrochloride (TCEP) was evaluated as potential agent for generation of -SH groups on 6D2 mAb. TCEP-treated 6D2 mAb was radiolabeled with (188)Re and its radiochemical purity and stability was measured by ITLC and HPLC and its immunoreactivity--by melanin-binding ELISA. The pharmacokinetics, therapeutic efficacy and acute hematologic toxicity studies were performed in nude mice bearing lightly pigmented A2058 human metastatic melanoma tumors.

CONCLUSIONS

We have developed radiolabeling and quality control procedures for melanin-binding (188)Re-6D2 mAb which made possible currently an on-going Phase I clinical trial in patients with metastatic melanoma.

Effect of ethosuximide on rest tremor in the MPTP monkey model

Based on the hypothesis that low-threshold calcium conductance in the thalamus might be involved in the pathophysiology of parkinsonian tremor, ethosuximide was given chronically to a monkey previously treated with MPTP and displaying exceptionally a typical rest tremor. After 5 days of daily treatment, the tremor was reduced by 60%. Diltiazem and verapamil which act on different calcium channels had no such effect. Ethosuximide also potentiated the anti-tremor effect of the dopamine D2 agonist LY-171555.

Effect of LY 171555 and CY 208-243 on tremor suppression in the MPTP monkey model of parkinsonism

The antitremor effect of the D2 agonist LY 171555 and of the D1 agonist CY 208-243 alone and in combination was tested in a monkey previously rendered parkinsonian by MPTP and displaying exceptionally a rest tremor in the limbs. The D2 agonist suppressed rest tremor in a dose-dependent fashion. The D1 agonist by itself had no effect but it potentiated the effect of a small dose of LY 171555.

Hepatotoxicity associated with overexposure to 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123)

1,1-Dichloro-2,2,2-trifluoroethane (HCFC-123) was evaluated as a substitute for trichlorofluoromethane (CFC-11), and it appeared that a permissible exposure limit of 50 ppm was justified. When HCFC-123 was introduced as a precision cleaning agent in a controlled operation, marked elevations in serum alanine transaminase and serum aspartase transaminase were noted in exposed workers. Sampling taken during start-up documented personal samples from 24-480 ppm (375 and 21 min, respectively) and area samples of 18-180 ppm (375 and 21 min, respectively). Personal and area samples collected after the liver abnormalities were identified ranged from 5-12 ppm. Exposure data were not available for the period when the abnormalities are suspected to have developed. Two models were developed to estimate exposure during the unmonitored period: (1) the entire plant as a homogenous box and (2) evaporation into smaller work zones. Modeling using the entire building estimated 8-hour time-weighted average (TWA) exposures of 10-35 ppm. Modeled estimates of work area and air exchange rates indicated that degreaser exposed workers could have experienced peak levels of 280-2,100 ppm (8-hour TWAs 252-1,630 ppm). Modeling of the work environment, estimated to be one-third of the volume of the entire open building, indicated peak exposures of 28-210 ppm (8-hour TWAs 25-163 ppm). These ranges estimate the minimum and maximum exposure levels. The best estimates, using 12 air changes per day, suggest peak levels around the degreaser of 635-2,100 ppm (8-hour TWA 499-1,630 ppm) and 63-207 ppm (8-hour TWAs 50-163 ppm) in the work area. These are the first estimates of exposure level associated with these hepatotoxic effects; all are significantly higher than personal and area samples collected for HCFC-123 after the liver abnormalities were identified.

Large-scale purification of recombinant human angiostatin

A process for the purification of recombinant human angiostatin (rhAngiostatin), produced by Pichia pastoris fermentation operated at the 2000-L scale, is reported. rhAngiostatin was recovered and purified directly from crude fermentation broth by cation exchange expanded bed adsorption chromatography. Anion exchange chromatography, hydroxyapatite chromatography, and hydrophobic interaction chromatography were used for further purification. Full-length rhAngiostatin was separated from rhAngiostatin molecules fragmented by endoproteolysis. On average, 140 g of rhAngiostatin was produced per batch, with an overall yield of 59% (n = 9). The purification process was completed in approximately 48 h and used only inexpensive and nontoxic raw materials. Methods development, process synthesis, and process scale-up data are presented and discussed.

Pulmonary epithelial sodium-channel dysfunction and excess airway liquid in pseudohypoaldosteronism

BACKGROUND

Active sodium absorption is the dominant mechanism of ion transport in airway epithelium, but its role in pulmonary physiology and airway host defense is unknown. To address this question, we studied the function of airway epithelial cells and determined the frequency of pulmonary symptoms in patients with systemic pseudohypoaldosteronism, a salt-losing disorder caused by loss-of-function mutations in the genes for the epithelial sodium channel.

METHODS

In nine patients 1.5 to 22 years of age who had systemic pseudohypoaldosteronism, we tested for mutations in the genes for the epithelial sodium channel, estimated the rate of sodium transport in the airway, determined the volume and ion composition of airway surface liquid, reviewed clinical features, collected laboratory data pertinent to pulmonary function, and, in three adults, measured mucociliary clearance.

RESULTS

The patients with systemic pseudohypoaldosteronism had loss-of-function mutations in the genes for the epithelial sodium-channel subunits, no sodium absorption from airway surfaces, and a volume of airway surface liquid that was more than twice the normal value. The mean (+/-SE) mucociliary transport rate was higher in the 3 adult patients than in 12 normal subjects (2.0+/-0.7 vs. 0.5+/-0.3 percent per minute, P=0.009). Young patients (those five years of age or less) all had recurrent episodes of chest congestion, coughing, and wheezing, but no airway infections with Staphylococcus aureus or Pseudomonas aeruginosa. Older patients (those more than five years of age) had less frequent respiratory symptoms.

CONCLUSIONS

Patients with systemic pseudohypoaldosteronism fail to absorb liquid from airway surfaces; the result is an increased volume of liquid in the airways. These results demonstrate that sodium transport has a role in regulating the volume of liquid on airway surfaces.

Changes in N-acetylaspartate and myo-inositol detected in the cerebral cortex of hamsters with Creutzfeldt-Jakob disease

The levels of several low-molecular-weight metabolites were measured in 1H nuclear magnetic resonance (NMR) spectra of extracts of Syrian hamster brain infected with Creutzfeldt-Jakob disease (CJD). Metabolite levels were determined in cerebral cortex in CJD-infected and age-matched controls at defined times (40, 65, 85, 105, and 135 days) during the 130- to 135-day incubation period to terminal disease. At 135 days, CJD-infected hamsters showed a significant decrease in N-acetylaspartate of 32% (p < 0.05) and an increase in myo-inositol of 67% (p < 0.001) from age-matched controls. At earlier times (40 to 110 days) levels of N-acetylaspartate and myo-inositol were not significantly different from controls. No significant changes were detected in the cortical levels of glutamate, aspartate, or GABA between 40 and 135 days. The late changes in N-acetylaspartate and myo-inositol in CJD-infected hamsters are similar to those observed in magnetic resonance spectroscopy studies of human CJD. Because they also correspond to the changes found in other dementias, including Alzheimer's disease and HIV dementia, these changes indicate converging pathogenetic pathways involved in many neurodegenerative diseases.

Laterality effects in the processing of melody and timbre

Laterality for the processing of melody and timbre was investigated in 64 right-handed non-musicians. In one block of dichotic-listening trials, participants listened for a prespecified target melody, and in a second block they listened for a prespecified target instrument. Females were more accurate on the left ear in the melody task (whereas males tended to show no ear advantage), but there were no significant ear differences in the timbre task for either sex. This supports the idea of a complementary sex-based pattern of lateralization, with males more strongly lateralized for verbal stimuli and females more strongly lateralized for non-verbal stimuli. No relation was observed between lambda measures for the two tasks, suggesting that laterality for melody processing is independent of laterality for timbre processing.

Analysis of acetate counter ion and inorganic impurities in pharmaceutical drug substances by capillary ion electrophoresis with conductivity detection

Capillary electrophoresis with conductivity detection is a versatile new method for the analysis of counter ions in pharmaceutical drug substances. It is a sensitive and linear technique for determining inorganic ions and short chain carboxylic acids such as acetate. Both acetate counter ion and inorganic impurities can be separated and determined in the same assay.

A mouse model for the renal salt-wasting syndrome pseudohypoaldosteronism

Aldosterone-dependent epithelial sodium transport in the distal nephron is mediated by the absorption of sodium through the highly selective, amiloride-sensitive epithelial sodium channel (ENaC) made of three homologous subunits (alpha, beta, and gamma). In human, autosomal recessive mutations of alpha, beta, or gammaENaC subunits cause pseudohypoaldosteronism type 1 (PHA-1), a renal salt-wasting syndrome characterized by severe hypovolemia, high plasma aldosterone, hyponatremia, life-threatening hyperkaliemia, and metabolic acidosis. In the mouse, inactivation of alphaENaC results in failure to clear fetal lung liquid at birth and in early neonatal death, preventing the observation of a PHA-1 renal phenotype. Transgenic expression of alphaENaC driven by a cytomegalovirus promoter in alphaENaC(-/-) knockout mice [alphaENaC(-/-)Tg] rescued the perinatal lethal pulmonary phenotype and partially restored Na+ transport in renal, colonic, and pulmonary epithelia. At days 5-9, however, alphaENaC(-/-)Tg mice showed clinical features of severe PHA-1 with metabolic acidosis, urinary salt-wasting, growth retardation, and 50% mortality. Adult alphaENaC(-/-)Tg survivors exhibited a compensated PHA-1 with normal acid/base and electrolyte values but 6-fold elevation of plasma aldosterone compared with wild-type littermate controls. We conclude that partial restoration of ENaC-mediated Na+ absorption in this transgenic mouse results in a mouse model for PHA-1.

Noncoordinated expression of alpha-, beta-, and gamma-subunit mRNAs of epithelial Na+ channel along rat respiratory tract

Na+ reabsorption from the epithelial surface of the respiratory tract plays a fundamental role in respiratory physiology. As in the epithelia of the renal collecting tubule and distal colon, Na+ enters across the luminal surface of respiratory epithelial cells via a recently cloned amiloride-sensitive multisubunit (alpha, beta, gamma) epithelial Na+ channel. We have examined the cellular expression at the mRNA level of the alpha-, beta-, and gamma-subunits of rat epithelial Na+ channel (rENaC) in the rat lung and upper airway epithelial cells using in situ hybridization. A large prevalence of alpha- and gamma-rENaC subunit expression (over beta) was found in tracheal epithelium, in a subpopulation of alveolar cells, presumably type II pneumocytes, and in nasal and tracheal gland acini. In contrast, equivalent levels of expression of all three subunits were detected in bronchiolar epithelium and in rat nasal gland ducts. This diversity of expression may reflect cell-specific functions of the amiloride-sensitive Na+ channel along the respiratory tract.

Early death due to defective neonatal lung liquid clearance in alpha-ENaC-deficient mice

The amiloride-sensitive epithelial sodium channel, ENaC, is a heteromultimeric protein made up of three homologous subunits (alpha, beta and gamma) (1,2). In vitro, assembly and expression of functional active sodium channels in the Xenopus oocyte is strictly dependent on alpha-ENaC--the beta and gamma subunits by themselves are unable to induce an amiloride-sensitive sodium current in this heterologous expression system (2). In vivo, ENaC constitutes the limiting step for sodium absorption in epithelial cells that line the distal renal tubule, distal colon and the duct of several exocrine glands. The adult lung expresses alpha, beta and gamma ENaC (3,4), and an amiloride-sensitive electrogenic sodium reabsorption has been documented in upper and lower airways (3-7), but it is not established whether this sodium transport is mediated by ENaC in vivo. We inactivated the mouse alpha-ENaC gene by gene targeting. Amiloride-sensitive electrogenic Na+ transport was abolished in airway epithelia from alpha-ENaC(-/-) mice. Alpha-ENaC(-/-) neonates developed respiratory distress and died within 40 h of birth from failure to clear their lungs of liquid. This study shows that ENaC plays a critical role in the adaptation of the newborn lung to air breathing.

Excitotoxic lateral pallidotomy does not relieve L-dopa-induced dyskinesia in MPTP parkinsonian monkeys

We attempted to relieve the marked overactivity known to occur in the lateral segment of the globus pallidus (GPL) in L-DOPA-induced dyskinesia (LID) by unilateral stereotaxic ibotenic acid lesioning of the GPL in 4 monkeys with MPTP-induced parkinsonism. Two already dyskinetic animals were pallidotomized to counteract LID once established, while 2 L-DOPA-naive MPTP-treated animals were pallidotomized before L-DOPA was ever administered in an attempt to prevent the development of the process conductive to LID. Acutely after the lesion, more prominent akinesia (particularly in the contralateral limbs) with contraversive body deviation and circling behavior were seen for 48 h. Flexor posturing of the contralateral forelimb persisted to a variable degree. When L-DOPA treatment was resumed or instituted 1 week postoperatively, ipsiversive circling behavior occurred in all animals and contralateral dyskinesia worsened in 3, whether L-DOPA or a selective dopamine D2 agonist was administered. Lesions in these 3 cases were fairly restricted to the GPL histologically. One monkey kept L-DOPA-naive before pallidotomy never developed LID contralaterally to the lesion despite treatment for several months. The lesion this time involved the entire GP. The fact that ablation of the GPL worsened LID suggests that a complex rearrangement of the balance of functional capacity between the GP and the subthalamic nucleus takes place in LID which is not amenable to correction merely by a lateral pallidotomy. Our observations also suggest that functional redundancy exists in striatopallidal circuits and that no single pathway is responsible for LID.

Effect of adding the D1 agonist CY 208-243 to chronic bromocriptine treatment. I: Evaluation of motor parameters in relation to striatal catecholamine content and dopamine receptors

A group of four cynomolgus monkeys previously rendered parkinsonian by the toxin 1-methyl-4-phenyl,1,2,3,6-tetrahydropyridine (MPTP) were observed in locomotion cages equipped with photocells during four periods of 7 days during which they received saline or two doses of the D1 agonist CY 208-243. The larger dose of 0.5 mg/kg produced a significant increase in locomotion in three of four animals. A second group of eight monkeys also previously rendered parkinsonian by MPTP and having received no other treatment were given a daily treatment of bromocriptine 1.66 mg/kg orally daily during 4 weeks. In four of the animals, after a week on bromocriptine alone, the D1 agonist CY 208-243 was added in increasing doses of 0.05, 0.1, and 0.5 mg/kg. The motor response as measured by locomotion, hand dexterity, and a disability score improved progressively at least in some of the animals on bromocriptine alone. The addition of CY 208-243 produced a more striking improvement of all three parameters, which appeared to be dose dependent. Biochemical analysis of the brain of these animals plus one control and one MPTP untreated monkey showed a > 90% loss of dopamine in the striatum in six of the eight treated monkeys. Both D2 and D1 dopamine receptors were increased in density by denervation, but both treatments abolished this increase for the D2 receptors while increasing the affinity of the D1 receptors.

Isobutylmethylxanthine fails to stimulate chloride secretion in cystic fibrosis airway epithelia

It has been proposed that a combination of an activated adenylyl cyclase and a high concentration of a phosphodiesterase inhibitor (isobutylmethylxanthine [IBMX], 5 mM) stimulates Cl- secretion mediated by the heterologously expressed cystic fibrosis transmembrane regulator protein carrying the most common cystic fibrosis (CF) mutation (delta F508). We tested whether Cl- secretion could be stimulated by this protocol in vitro and in vivo in CF airway epithelia expressing endogenous delta F508 CFTR protein. In cultured airway preparations, forskolin (a direct adenylyl cyclase activator) stimulated Cl- secretion in amiloride-pretreated normal (delta Isc = 7.1 +/- 1.7 microA.cm-2) but not CF tissues (delta Isc = -02 +/- 0.1 microA.cm-2). Unexpectedly, IBMX partially inhibited the forskolin-induced Cl- secretion in normal tissues; IBMX addition had no effect on CF tissues. Direct measurements of cell cAMP concentrations revealed that 0.1 mM IBMX and forskolin produced the maximum levels of cell cAMP levels attainable with this drug combination, and 5 mM IBMX was without further effect. The combination of forskolin (10(-5) M) and isoproterenol, an adenylyl cyclase activator (10(-5) M), produced approximately 3 times higher levels of cAMP than forskolin/IBMX but also did not induce Cl- secretion in CF tissues. Studies of Cl- secretion in vivo, assessed by the transepithelial electric potential difference (PD), showed that isoproterenol (10(-5) M) stimulated Cl- secretion (delta PD = -16.3 +/- 4.3 mV; n = 4) in nasal epithelia of normal subjects but not in CF patients homozygous for the delta F508 mutation (delta PD = -2.6 +/- 1.9 mV; n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro micronucleus bioassay of human peripheral lymphocytes for adriamycin in the presence of cyclophosphamide and urines of patients administered anticancer drugs

The aim of this study was to develop an in vitro human peripheral lymphocyte micronucleus bioassay involving phytohemagglutinin stimulant for urines containing adriamycin (ADR) and cyclophosphamide (CP). In vitro studies with defined concentrations of ADR, CP, and fresh urine showed that mitotic indices and micronuclei counts/1,000 cells had to be log (X + 1) transformed to be able to use parametric statistics and that a specific micronucleus assay for ADR in the presence of CP and urine for 5-15 ng ADR/mL had been developed. Whereas CP alone could be detected between 196-522 micrograms/mL, this effect was abolished in the presence of 15 ng ADR/mL. Interdonor variabilities relative to ADR sensitivity and CP linear dynamic range were marked, but intradonor variability was small. The MN bioassay tolerated < 10% urine. Results for urines from nine patients receiving antineoplastic drugs (CP, all; ADR, 3; 5-fluorouracil, 3; methotrexate, 3; vincristine, 4; procarbazine, 1; and megestrol acetate, 1) showed that only 1/3 patients given ADR were detected, and two others not given ADR were positive. All frozen urines from the 12 control subjects and the nine patients exhibited depressed mitotic index, with, however, no control patient urines inducing increased micronuclei. Two patients had urines of undefined genotoxic potential since undepressed mitotic indices were not attainable by dilution. The effects of combination chemotherapy in addition to freezing and storage influences were complex. More research is required to be able to interpret the results.

Effect of clonidine and atropine on rest tremor in the MPTP monkey model of parkinsonism

The purported alpha 2-adrenergic agonist clonidine was found to inhibit rest tremor at doses of 0.023-0.1 mg/kg in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine monkey model of parkinsonism. The effect was dose dependent, but sedation and reduced mobility were observed. Atropine at doses of 0.1-1 mg/kg also reduced tremor in a dose-dependent fashion, but side-effects in the form of agitation, dilated pupils, and dry mouth were seen. When the two drugs were combined, however, we saw a significant potentiation of the antitremor effect. We could even abolish tremor with doses of atropine and clonidine that by themselves were without effect. The side-effects were almost eliminated by the combination.

Expression of mucin synthesis and secretion in human tracheobronchial epithelial cells grown in culture

The effects of culture conditions on growth and differentiation of human tracheobronchial epithelial (HTBE) cells have been defined. Epithelial cells were dissociated from tissues by protease treatment and were plated on tissue culture dishes in F12 medium supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, cholera toxin, bovine hypothalamus extract, and retinol. HTBE cells did not express any mucociliary function (ciliogenesis or mucin secretion) on tissue culture plastic, but they could be passaged 3 to 5 times with a total of 10 to 25 population doublings. Cells from early passages re-express both these functions when transplanted to tracheal grafts. When tissue culture plates were coated with collagen film or collagen gel substrata, cell attachment and proliferation were stimulated. However, the expression of mucous cell function in culture occurred only when cells were plated on collagen gel substrata and vitamin A (retinol) was present in the medium. Mucous cell differentiation under optimal conditions was defined by ultrastructural studies, by immunologic studies with mucin-specific monoclonal antibodies, and by carbohydrate and amino acid compositional analyses of mucin-like glycoproteins purified from culture medium. These results demonstrate for the first time that HTBE cells can express mucin synthesis and secretion under appropriate culture conditions.

Effect of D1 receptor stimulation in normal and MPTP monkeys

The effect of a selective agonist of the dopamine D1 receptor (SKF 38393) and of the D2 receptor (LY-171555) was tested acutely in normal and in monkeys with a parkinsonian syndrome induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The D2 agonist induced a strong locomotor response and lingual dyskinesia in both normal and parkinsonian monkeys. The D1 agonist however had no locomotor effect by itself but induced tongue protrusions in normal monkeys only. It appeared to potentiate the dyskinetic effect of LY 171555 in MPTP monkeys but it antagonized the locomotor action of the D2 agonist in both normal and MPTP monkeys. The selective D1 and D2 antagonists SCH 23390 and sulpiride were also tested. Both compounds were able to suppress the dyskinetic action of the combined agonists in normal animals but only the D2 antagonist was effective in the same conditions in MPTP monkeys. These findings emphasize the importance of the D2 receptor in mediating the locomotor response as well as dyskinesia in monkeys.

Phenytoin prodrug: preclinical and clinical studies

The currently available phenytoin (PHT) solution has many disadvantages stemming from poor aqueous solubility of PHT. A novel approach to solve the problem has been the synthesis of a phosphate ester of PHT (PHT prodrug ACC-9653). This water-soluble compound is metabolized rapidly into PO4 and PHT. A four center open-label, baseline-controlled study of 43 patients with epilepsy maintained on oral twice-daily PHT monotherapy was performed to evaluate the safety and pharmacokinetic profile of the prodrug. Patients received an i.v. or i.m. dose of ACC-9653 at a dose equivalent to the patients' morning dose of PHT. Intravenous dosages were infused at a rate of 75 mg/min, and i.m. dosages were given as one or two injections. After a period of 6 days, during which patients were again maintained with oral PHT, they were given a dose of ACC-9653 via whichever route they had not yet received. The Tmax of the prodrug averaged 5.7 and 36 min (0.095 and 0.606 h) after i.v. and i.m. administrations, respectively. The elimination half-life of ACC-9653 (conversion from prodrug to PHT) after i.v. and i.m. administration was 8.4 and 32.7 min (0.140 and 0.545 h), respectively, and both were independent of the dose. The plasma clearance of ACC-9653 was not dependent on dose or route of administration and averaged 19.8 +/- 1.16 and 17.8 +/- 0.83 L/h after i.v. and i.m. administrations, respectively. The area under curve ratio of PHT after i.m. and i.v. ACC-9653 was 1.17 +/- 0.13 which was not significantly different from 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Uterine leiomyosarcoma with cardiac metastases

Leiomyosarcoma metastatic to the heart is rare and is usually fatal. The authors present the case of a 58-year-old woman who had a history of uterine leiomyosarcoma. Echocardiography and cardiac catheterization revealed a large right ventricular mass. Computed tomography confirmed the presence of the mass which extended into the pulmonary artery. The inferior vena cava was free of disease. At operation, a large tumour originating in the right ventricle and protruding through the pulmonary valve was found. Histologically, it was a leiomyosarcoma. Because there were numerous septal and intramural foci of tumour, complete resection was impossible, but palliative resection was performed successfully and the patient was alive and active 1 year after operation.

The introduction of biologically active foreign genes into human respiratory epithelial cells using electroporation

A simple method for introducing genes into respiratory epithelial cells would assist molecular studies of a variety of pulmonary disorders. Several different techniques for introducing foreign DNA into cells have been described but have either not been useful for respiratory epithelial cells or are difficult and cumbersome to perform. Electroporation is a simple technique that consists of exposing a cell-DNA suspension to an electric shock. Although it has been used to introduce genes into a variety of cell types, it has not previously been applied to respiratory epithelial cells. Human nasal epithelial cells were transfected with the plasmid pRSVCAT, which is an expression vector containing the origin of replication of pBR322 coupled to the Rous sarcoma virus (RSV) long terminal repeat (LTR) region driving the coding sequence for the chloramphenicol acetyltransferase (CAT) gene. The CAT gene is useful for determining optimal conditions for electroporation since it is not normally present in eukaryotic cells, and CAT activity correlates with the level of CAT mRNA; this provides a measure of expression of introduced foreign genes. Successful expression of the CAT gene was demonstrated by electroporation, whereas calcium phosphate transfection resulted in very low CAT activity. Optimal conditions for electroporation of respiratory epithelial cells were determined. Electroporating nasal epithelial cells using 500 volts, a DNA concentration of 10 micrograms/ml, and a sucrose buffer yielded the highest CAT activity, which peaked at 48 h after electroporation.

[Animal models of tardive dyskinesia]

It is possible to induce in monkeys abnormal movements of the mouth and tongue resembling strikingly tardive dyskinesia. Such movements can be induced by chronic treatment with neuroleptics or by lesions placed in the habenular interpeduncular tract or nucleus parafascicularis thalami. Dopaminergic D1 and D2 receptors are involved in the modulation of such movements.

Behavioral and biochemical effect of chronic treatment with D-1 and/or D-2 dopamine agonists in MPTP monkeys

Monkeys developed a severe parkinsonian syndrome after intravenous administration of (MPTP). L-DOPA/carbidopa (D-1 and D-2) or bromocriptine (D-2) treatment relieved the parkinsonian symptoms, whereas SKF 38393 (D-1) was ineffective. No dyskinesia was seen in monkeys receiving bromocriptine or SKF 38393 as opposed to the L-DOPA-treated animals, in which the dyskinetic response appeared to increased with time. MPTP induced a significant increase (25%, P less than 0.01) in the number of [3H]spiperone binding sites (Bmax) in the caudate nucleus and in putamen. The Bmax of spiperone binding in the L-DOPA-treated monkeys was on average 18% lower (P less than 0.01) than that of the animals treated with MPTP alone. The Bmax for the bromocriptine-treated group was 29% (P less than 0.01) less than that in the MPTP-treated group or 11% (P less than 0.05) less than that in the L-DOPA-treated monkeys. The SKF 38393 treatment induced a 23% (P less than 0.01) decrease in the Bmax as compared to that of animals treated with MPTP alone, and no significant change compared to the L-DOPA- or bromocriptine-treated animals. These results suggest that stimulation of D-1 and D-2 dopamine receptors can differently influence the mechanisms controlling dopamine agonist-induced dyskinesia in MPTP-treated monkeys.

Assessment of maximal expiratory pressure in healthy adults

Maximal static expiratory pressure developed at the mouth (PEmax) provides a useful clinical index of expiratory muscle function; however, the range of normal values among laboratories shows considerable variation. We examined the hypothesis that the wide variability could be attributable to the differences in technique among laboratories. We measured PEmax at functional residual capacity (PEmax FRC) in 28 healthy subjects using the following five techniques: 1) using a scuba-type mouthpiece with the cheeks supported by the hands ("hands on"), 2) without supporting the cheeks ("no hands"), 3) using a rigid, circular mouthpiece (2.8 cm ID, "tube"), 4) using the scuba-type mouthpiece but with the cheeks supported by an observer ("other hands"), and 5) using a large-bore circular mouthpiece (4.1 cm ID, "new tube"). Mean PEmax FRC obtained with hands on was significantly higher than no-hands and tube methods. PEmax FRC values obtained by the other-hands and new-tube maneuvers were similar to the hands-on maneuver. We conclude that the technique used to measure PEmax FRC can significantly affect the results and suggest that it should be measured using a large-bore circular mouthpiece or a scuba-diving mouthpiece with the cheeks supported.

Chloroprene and isoprene: cytogenetic studies in mice

Groups of male B6C3F1 mice (n = 15) were exposed for 6 h per day to ambient air, to chloroprene (12, 32, 80, 200 p.p.m.) or to isoprene (438, 1750 and 7000 p.p.m.) on 12 days. These compounds are the 2-chloro and the 2-methyl analogues, respectively, of 1,3-butadiene, a genotoxic and carcinogenic chemical in B6C3F1 mice. Exposure to chloroprene resulted in a 100% incidence of mortality among the mice exposed to 200 p.p.m. At concentrations of 80 p.p.m. and below, chloroprene neither induced a significant increase in chromosomal aberrations (CA), sister chromatid exchanges (SCE) or micronucleated erythrocytes, nor significantly altered the rate of erythropoiesis or of bone marrow cellular proliferation kinetics. However, the mitotic index (MI) in the bone marrow of chloroprene-exposed mice was significantly increased. Under similar conditions, exposure to isoprene induced significant increases at all concentrations in the frequency of SCE in bone marrow cells and in the levels of micronucleated polychromatic erythrocytes (PCE) and of micronucleated normochromatic erythrocytes in peripheral blood. In addition, a significant lengthening of the bone marrow average generation time and a significant decrease in the percentage of circulating PCE was detected. However, exposure to isoprene did not induce in bone marrow a significant increase in the frequency of CA nor did the exposure significantly alter the MI. The dose-response curves for SCE and micronuclei induction were non-linear, appearing to saturate at 438 and 1750 p.p.m., respectively. These results suggest that, similarly to butadiene, inhaled isoprene can be expected to induce tumors at multiple sites in B6C3F1 mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of mouthpiece, noseclips, and head position on airway area measured by acoustic reflections

To investigate whether it is possible to simplify the methodology of measuring airway area by acoustic reflections, we measured upper airway area in 10 healthy subjects during tidal breathing according to seven different protocols. Three protocols employed custom-made bulky mouthpiece with or without nose-clips, two protocols used a scuba-diving mouthpiece and cotton balls placed in the nostrils instead of noseclips, and two protocols employed neck flexion and extension. We found no significant difference in average pharyngeal, glottic, and tracheal areas for any of the protocols except for neck flexion, which was associated with a significantly lower mean pharyngeal area. Intraindividual variabilities were comparable for all protocols, except for protocol employing the customary bulky mouthpiece and no noseclips, which consistently resulted in the most variable measurements of area for all three airway segments: pharynx, glottis, and trachea. Furthermore, we found that the protocol employing the scuba-diving mouthpiece with or without cotton balls in the nostrils resulted in the lowest number of unacceptable measurements. We conclude that measurements of airway area by acoustic reflections may be further simplified by using a scuba-diving mouthpiece without noseclips; furthermore, control of head position during measurements is not critical provided there is no obvious neck flexion.

Changes in pharyngeal cross-sectional area with posture and application of continuous positive airway pressure in patients with obstructive sleep apnea

In an attempt to elucidate whether changes in posture (from sitting to supine) result in reduction in pharyngeal area, thus promoting pharyngeal occlusion during sleep in so predisposed persons, we studied 12 snoring apneic patients and 6 snoring nonapneic control subjects. in all subjects, we employed acoustic reflection technique to measure pharyngeal area at FRC sitting and supine. We also examined changes in pharyngeal area resulting from the application of positive intrapharyngeal pressure in sitting and supine posture. We found that (1) pharyngeal cross-sectional area at FRC was similar in both groups, (2) decrease in pharyngeal area with assumption of supine posture was also similar in both groups (21 +/- 11% in patients with OSA versus 15 +/- 13% in nonapneic control subjects), and (3) pharyngeal distensibility was significantly higher in apneic snorers than in nonapneic control subjects (0.090 +/- 0.039 cm H2O-1 in apneic snorers versus 0.032 +/- 0.027 cm H2O-1 in nonapneic control subjects; p less than 0.005). We conclude that changes in posture alone are not sufficient to convert a snorer into a patient with OSA; however, when physiologic abnormalities ("floppy" pharynx) are superimposed on postural reduction in pharyngeal area, airway occlusion results.

An isovolume method for analysis of density dependence of maximal expiratory flows

The usual method of measuring density dependence of maximum expiratory flows is superimposition at total lung capacity or residual volume of maximum expiratory flow volume (MEFV) curves obtained breathing air and a mixture of 80% He plus 20% O2 (HeO2). A major problem with this technique is the large variability in results, which has been thought to be due to errors in matching lung volumes on both gases. Accordingly, we obtained MEFV curves breathing air and HeO2 using a bag-in-the-box system so that the curves breathing the two gas mixtures could be directly superimposed without removing the mouthpiece (isovolume). Ten healthy, nonsmoking subjects performed MEFV curves on each gas mixture for six consecutive experiments. We compared the increase in flow at 50% of vital capacity (delta Vmax50) and volume of isoflow (Viso) by superimposing and matching the MEFV curves at total lung capacity, at residual volume, and using the isovolume method. The variability of each method was assessed by the mean intersubject and intrasubject coefficients of variation. In all subjects, the mean delta Vmax50 and Viso as well as their corresponding coefficients of variation were not significantly different among the three methods. We conclude that, in healthy nonsmoking young adults, the method chosen for superimposing and matching MEFV curves has no effect on the variability of delta Vmax50 and Viso.

Comparative cytogenetic analysis of bone marrow damage induced in male B6C3F1 mice by multiple exposures to gaseous 1,3-butadiene

Groups of male B6C3F1 mice (N = 12) were exposed to ambient air or to gaseous 1,3-butadiene (BD) at 6.25, 62.5, and 625 ppm for 10 exposure days (6 hr + T90/day). Exposure to BD induced in bone marrow: 1) a significant increase in the frequency of chromosomal aberrations (CA); 2) a significant elevation in the frequency of sister chromatid exchanges (SCE); 3) a significant lengthening of the average generation time (AGT); 4) a significant depression in the mitotic index (MI); and, as measured in the peripheral blood, 5) a significant increase in the proportion of circulating polychromatic erythrocytes (%PCE), and 6) a significant increase in the level of micronucleated PCE (MN-PCE) and micronucleated normochromatic erythrocytes (MN-NCE). The most sensitive indicator of genotoxic damage was the frequency of SCE (significant at 6.25 ppm), followed by MN-PCE levels (significant at 62.5 ppm), and then by CA and MN-NCE frequencies (significant at 625 ppm). The most sensitive measure of cytotoxic damage was AGT (significant at 62.5 ppm), followed by %PCE (significant at 625 ppm), and then by MI (significant by trend test only). Because each cytogenetic endpoint was evaluated in every animal, a correlation analysis was conducted to evaluate the degree of concordance among the various indicators of genotoxic and cytotoxic damage. The extent of concordance ranged from a very good correlation between the induction of MN-PCE and the induction of SCE (correlation coefficient r = 0.9562) to the lack of a significant correlation between the depression in the MI and any other endpoint (r less than 0.37).

Long-term effects of MPTP on central and peripheral catecholamine and indoleamine concentrations in monkeys

5 Macaca fascicularis monkeys developed a severe parkinsonian syndrome in the days following intravenous administration of the toxin MPTP. One monkey remained untreated while two groups of two animals were treated daily for 5 months with supramaximal oral doses of either Sinemet or bromocriptine. Both drugs relieved the parkinsonian symptoms. Plasma prolactin concentrations were elevated in MPTP-treated monkeys compared to intact monkeys. MPTP caused a rapid decrease of homovanillic acid (HVA) concentrations in the CSF of these monkeys within days of the toxin injection and these values remained low until sacrifice of the animals 5 months later. By contrast, CSF 5-hydroxyindoleacetic acid (5-HIAA) concentrations were elevated a few days after the start of MPTP treatment and these values returned to control levels by 5 months. Five months after the start of MPTP treatment, epinephrine (E) and dopamine (DA) levels were decreased in the adrenal medulla while the norepinephrine (NE) concentration remained unchanged. Catecholamines were assayed in the caudate putamen, nucleus accumbens, amygdala and frontal cortex of these monkeys. NE concentrations were decreased in the frontal cortex of MPTP-treated monkeys while a decrease of E concentrations after MPTP was only observed in the n. accumbens. Dopamine and its metabolites dihydroxyphenylacetic acid (DOPAC) and HVA were reduced in the caudate, putamen, n. accumbens and frontal cortex. Our results show that MPTP treatment in the long-term (5 months) not only affects the dopaminergic system of the caudate-putamen but also has effects on dopaminergic systems in other regions as well as on noradrenergic and adrenergic systems in the brain and the periphery.