Effects of substance P on extracellular dopamine in neostriatum and nucleus accumbens

Microdialysis was used to monitor changes in dopamine release in the neostriatum and nucleus accumbens after peripheral administration of substance P in freely moving rats. Substance P in a dose of 50 micrograms/kg produced a steady moderate increase in dopamine levels in the neostriatum, which persisted for at least 5 h. In contrast, a dose of 250 micrograms/kg caused an acute increase in dopamine levels in the nucleus accumbens, which lasted about 2 h. These data suggest that the peripheral administration of substance P can influence dopamine release in mesolimbic and mesostriatal terminals.

Lateralized changes in behavior and striatal dopamine release following unilateral tactile stimulation of the perioral region: a microdialysis study

Intracranial microdialysis was used to measure dopamine (DA) release in the ventrolateral neostriatum of freely moving rats before and after unilateral tactile stimulation was applied to the orofacial region. Several behavioral parameters which have been linked to changes in nigrostriatal DA transmission (scanning, or snout contact with the walls of the observation chamber, turning and locomotion) were measured as well. Orofacial stimulation was followed by an asymmetrical increase in DA release with concentrations of transmitter higher in the neostriatum ipsilateral to the side of stimulation. Asymmetrical scanning behavior was observed during the time period when DA release was asymmetric, with rats favoring use of the side of the face contralateral to increased DA release. Increases in the DA metabolites DOPAC and HVA were found in the striatum ipsilateral to stimulation, but were delayed 40 min following the increase in DA.

Acquisition and quantification of ion images with a camera-based detection system and classical quantification algorithms

The quantitative analytical characteristics of a camera-based detection system for secondary ion microscopy are studied in detail. Through multiple exposures, ion images with large dynamic ranges are obtained. The quantification of these images by the sensitivity factor method and the matrix ion species ratio method is described and evaluated by the analysis of steel and aluminum standard reference materials.

On the use of laser microprobe mass spectrometry for the analysis of organic biomolecules

Laser microprobe mass spectrometry has been applied to a variety of organic polyfunctional molecules, covering a wide range of polarity and mass spectrometric behaviour. The technique apparently combines desorption under relatively soft conditions with extensive fragmentation and hence allows much structural information from intactly released thermolabiles to be obtained. The mass spectra appear unfamiliar in comparison to conventional techniques. Interpretation is attempted in a purely empirical way by means of the evidence from our database and tentative hypotheses to rationalize the desorption and ionization by laser microbeam irradiation of organic solids. Selected examples are presented to illustrate the potential and limitations of the method in the field of biomolecules, such as pyridoxine and pyridoxal phosphate, nucleosides, nucleotides and related analogues, drugs and the corresponding N-oxides.

Focal subdermal toxicity with subcutaneous opioid infusion in patients with cancer pain

Few significant side effects have been reported from the treatment of cancer pain by subcutaneous infusion of opioids. In this prospective year-long study, 8 of 13 patients treated by this technique experienced painful chronic focal toxicity, manifested by induration, erythema and subdermal necrosis during subcutaneous analgesia therapy. A hydraulic-irritation effect is suggested.

Emergency intravenous sedation of the delirious, medically ill patient

More than 2,000 medically ill patients with delirium have been treated by intravenous administration of a combination of haloperidol and lorazepam. The protocol was developed over 8 years at two major cancer centers in the United States and Canada. The addition of the potent benzodiazepine to the neuroleptic produces rapid and safe symptomatic sedation in emergency conditions and allows the use of lower doses of haloperidol. The combination was first attempted when doses of haloperidol as high as 350 mg failed to provide rapid emergency neurobehavioral control. All patients treated to date had cancer, and all were suffering multisystem organ failure. Hourly doses of each drug as high as 10 mg for as long as 15 days have been shown to be safe and effective in the most critically ill patient with delirium. Patients generally respond to the first one or two doses and, in most cases, less than 100 mg/day of each drug is required. The addition of the opioid hydromorphone makes the combination ideal for the treatment of intractable pain in terminally ill cancer patients. This polypharmacological approach is advocated as the method of choice for emergency sedation of the delirious patient as well as for palliative care.

Interferon-induced organic mental disorders associated with unsuspected pre-existing neurologic abnormalities

Eleven patients ranging in age from 52 to 80 years, undergoing treatment for cancer with various preparations of interferon received neurobehavioral evaluations after experiencing unexpectedly severe organic mental disorders. The reactions ranged from delirium to extrapyramidal symptoms, mania, and neurasthenia with catatonic episodes. Computed tomographic (CT) scans of the brain disclosed unsuspected pre-existing neurologic abnormalities in all patients, including cerebral atrophy (6/11), brain metastases (4/11), and evidence of head injury incurred 40 years earlier (1/11). These findings suggest that cancer patients with pre-existing neurologic dysfunctions are at increased risk for severe interferon neurotoxicity.

Intraventricular microdialysis: a new method for determining monoamine metabolite concentrations in the cerebrospinal fluid of freely moving rats

A new method is described to estimate the cerebrospinal fluid (CSF) concentrations of monoamine metabolites (dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA] in the lateral ventricle of freely moving rats by use of in vivo microdialysis. Both the baseline concentrations of these metabolites and the rate of dopamine (DA) turnover (estimated by the accumulation of total DA metabolites after 200 mg/kg probenecid) were within the range reported when other methods were used to sample CSF. A series of preliminary studies were conducted to demonstrate that this method can be used to repeatedly sample CSF, and to show that the method is sensitive to local changes in dopaminergic activity induced by lesions, drugs or grafts. (1) Unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra produced a significant decrease in the CSF concentrations of DOPAC and HVA ipsilateral to the lesion, relative to the contralateral side or to concentrations in animals without lesions. (2) When left and right lateral ventricles were sampled simultaneously in animals with a unilateral 6-OHDA lesion, haloperidol induced an increase in DOPAC and HVA concentrations in CSF on both sides of the brain. Interestingly, the haloperidol-induced increase in CSF concentrations of DA metabolites was greater adjacent to the intact striatum of rats with unilateral 6-OHDA lesions than in animals with no lesion. (3) Finally, in animals with adrenal medulla tissue grafted into the lateral ventricle there was an increase in the CSF concentration of DOPAC compared to pregraft values or to those of animals with control grafts.

Treatment of severe, refractory agitation with a haloperidol drip

A case of agitated delirium secondary to bilateral occipital cerebral infarctions in a cancer patient was refractory to trials of large doses of intravenous psychotropic agents, but continuous intravenous infusion of haloperidol controlled agitation rapidly and safely. A total haloperidol dose of 600 mg/day was used without complications. Haloperidol by continuous infusion should be considered in the management of severe, refractory agitation in patients who are medically ill.