A new formalin test allowing simultaneous evaluation of cardiovascular and nociceptive responses

The formalin test for nociception, predominantly used with rodents, is characterized by continuous pain due to tissue injury induced by formalin. In addition to the pain generated by formalin itself, the classical formalin test for nociception comprises a number of additional strong stressful events such as restraint and injury caused by needle insertion. These events have hampered its use as a model of stress employing continuous pain as a stress stimulus. We describe here a new, simple method of a subcutaneous application of formalin in conscious rats without restraint and needle insertion. Formalin or physiological saline (controls) was injected subcutaneously through a chronically implanted catheter in the region of the lower leg. In most animals, the cardiovascular and behavioural responses to subcutaneously injected formalin were biphasic. The early phase was quantitatively characterized. Formalin (2.5%, 50 microL) induced a marked increase in mean arterial pressure and heart rate. Maximal increases occurred during the first 3 min after formalin injection and were followed by a gradual decline of both cardiovascular parameters to levels higher than the preinjection baseline. Subcutaneous saline injection did not induce any changes in mean arterial pressure and heart rate. The behavioural response to formalin featured intensive licking and biting of the injection site. The behavioural response to subcutaneous saline did not differ from the spontaneous behavioural activity recorded in noninjected rats. Subcutaneously injected formalin induced an immediate increase in plasma corticotrophin (ACTH), corticosterone, noradrenaline, and adrenaline levels, and all hormones remained increased during the whole observation period (60 min). Adrenaline and noradrenaline levels in plasma were slightly, but significantly, elevated during the initial 5 min after subcutaneous saline application but returned to basal values after 15 min. The magnitude of the hormonal responses characterizes the described formalin test as a moderate stress stimulus. The complex response pattern to formalin injected through the subcutaneous catheter is brought about exclusively by pain generated by formalin-induced tissue injury. The described technique of subcutaneous formalin injection represents a new tool to study mechanisms activating brain neuronal circuits that generate the cardiovascular, endocrine, and behavioural responses of the reaction to pain.

Crystallization and preliminary X-ray diffraction data of two different human low-density lipoprotein (LDL) subfractions

Human LDL subfractions LDL-2 (d = 1.031-1.034 g/ml) and LDL-5 (d = 1.040-1.044 g/ml) were crystallized in two different crystal forms by using polyethylene glycol as a precipitant. Both fractions were from one donor. Crystals of LDL-5 were yellow, hexagonal, and showed no dichroism. Crystals of LDL-2 were of the same color, had a rodlike shape with notches at both ends, and were highly dichroitic. LDL-2 crystals diffracted to a resolution of 29 A by using synchrotron radiation. Indexing in P1 resulted in preliminary parameters for the reduced cell of a = 171 A, b = 438 A, c = 519 A, alpha = 102 degrees, beta = 99 degrees, gamma = 91. These dimensions are consistent with the size of LDL particles. Using Fourier transform infrared spectroscopy (FTIR) and agarose gel electrophoresis, we could further confirm that the crystals consist of LDL. The FTIR spectrum showed bands characteristic for lipids and protein. Dissolved crystals exhibited a mobility similar to native LDL in agarose gels and could be stained with anti-human apolipoprotein B (apoB).

Aqueduct occlusion does not impair feeding induced by either third or fourth ventricle galanin injection

Exogenous galanin stimulates feeding when injected into forebrain and hindbrain sites, including the third and fourth ventricles (3V and 4V), amygdala, paraventricular nucleus of the hypothalamus (PVN), and nucleus of the solitary tract (NTS). Because the PVN and NTS border the ventricular space, it is possible that feeding stimulated by injection of galanin at these sites may be caused by the transport of galanin through the ventricular system to a remote site of action. The role of ventricular transport of galanin between the 3V and 4V in galanin-induced feeding was examined in this study. Rats were implanted with two guide cannula assemblies: one dorsal to the mesencephalic aqueduct and the other in the 3V or 4V. Feeding in response to 3V or 4V galanin injection was first measured after sham-occlusion of the aqueduct. Subsequently, flow of cerebrospinal fluid between the forebrain and hindbrain ventricles was acutely interrupted by injection of a silicone grease plug into the mesencephalic aqueduct just before assessment of the feeding response to 4V or 3V galanin injection. Aqueduct occlusion did not alter the feeding induced by either 3V or 4V galanin injection, indicating that galanin terminals in both the diencephalon and hindbrain are involved in control of food intake.

Diagnostic and prognostic value of cerebral 31P magnetic resonance spectroscopy in neonates with perinatal asphyxia

The impact of depressed neonatal cerebral oxidative phosphorylation for diagnosing the severity of perinatal asphyxia was estimated by correlating the concentrations of phosphocreatine (PCr) and ATP as determined by magnetic resonance spectroscopy with the degree of hypoxic-ischemic encephalopathy (HIE) in 23 asphyxiated term neonates. Ten healthy age-matched neonates served as controls. In patients, the mean concentrations +/- SD of PCr and ATP were 0.99 +/- 0.46 mmol/L (1.6 +/- 0.2 mmol/L) and 0.99 +/- 0.35 mmol/L (1.7 +/- 0.2 mmol/L), respectively (normal values in parentheses). [PCr] and [ATP] correlated significantly with the severity of HIE (r = 0.85 and 0.9, respectively, p < 0.001), indicating that the neonatal encephalopathy is the clinical manifestation of a marred brain energy metabolism. Neurodevelopmental outcome was evaluated in 21 children at 3, 9, and 18 mo. Seven infants had multiple impairments, five were moderately handicapped, five had only mild symptoms, and four were normal. There was a significant correlation between the cerebral concentrations of PCr or ATP at birth and outcome (r = 0.8, p < 0.001) and between the degree of neonatal neurologic depression and outcome (r = 0.7). More important, the outcome of neonates with moderate HIE could better be predicted with information from quantitative 31P magnetic resonance spectroscopy than from neurologic examinations. In general, the accuracy of outcome predictability could significantly be increased by adding results from 31P magnetic resonance spectroscopy to the neonatal neurologic score, but not vice versa. No correlation with outcome was found for other perinatal risk factors, including Apgar score.

Haemolysis in hepatitis A virus infections coinciding with the occurrence of autoantibodies against triosephosphate isomerase and the reactivation of latent persistent Epstein-Barr virus infection

Haemolysis has been observed frequently as a complication of acute hepatitis A virus (HAV) infection. However, the pathogenic mechanism has not been elucidated completely. In individual cases the detection of anti-erythrocyte antibodies of unknown specificity was described. The raised serum IgM fraction was shown to consist partially of autoantibodies. Previously, we detected autoantibodies of immunoglobulin class M directed against triosephosphate isomerase (IgM anti-TPI) in patients with infectious mononucleosis. These autoantibodies are able to induce haemolysis. In this study the occurrence of IgM anti-TPI in acute HAV infections and other viral diseases has been investigated. In 33 of 134 patients suffering from HAV infection (IgM anti-TPI was detected. Haematological and chemical data were available from seven of these 33 patients. Mild-to-moderate signs of haemolysis correlating with the IgM anti-TPI titre in the follow-up examinations were demonstrated. The presence of IgM anti-TPI in HAV infections is connected with a reactivation of a latent persistent EBV infection. In other viral infections both the detection of IgM anti-TPI and evidence of a reactivated EBV infection is rare. Thus, we anticipate that IgM anti-TPI antibodies occurring with the reactivation of a latent persistent EBV infection take part in provoking haemolysis in acute HAV infections.

The effects of low-, medium-, and high-fat diets on 2-deoxy-D-glucose- and mercaptoacetate-induced feeding

The present study examined the feeding responses stimulated by low suprathreshold and optimal doses of 2-DG and MA in three groups of rats maintained and tested on low (4.3%), medium (13.5%), or high (66.4%) fat diets. Results show that diet alters the response to 2-DG and MA. Rats on the low-fat diet significantly increased food intake after both the low and high doses of 2-DG. Rats on the medium- and high-fat diet significantly increased food intake after both the low and high doses of 2-DG. Rats on the medium- and high-fat diets significantly increased food intake only after the high dose of 2-DG. After administration of the low and high doses of MA, rats on the high-fat diet ate significantly more. However, rats on the low- and medium-fat diets significantly increased food intake only after the high dose of MA. These results suggest that diet-induced dependence of rats on fat or carbohydrate metabolism alters the sensitivity of systems controlling food intake in response to deficits in the availability of these specific metabolic fuels.

Feeding induced by pharmacological blockade of fatty acid metabolism is selectively attenuated by hindbrain injections of the galanin receptor antagonist, M40

Galanin has been shown to stimulate feeding when injected intracranially in rats. Lesion and Fos studies have shown that the neural pathway for feeding stimulated by mercaptoacetate (MA)-induced blockade of fatty acid oxidation includes several structures rich in galanin cell bodies or terminals. In the present experiment, we examined the role of hindbrain galanin in feeding stimulated by MA. We found that galanin (1 nmol) stimulates feeding when injected in the nucleus of the solitary tract (NTS), a site that is crucial for MA-induced feeding, or into the fourth ventricle (4V, 1 or 5 nmol) and that NTS or 4V injections of the galanin receptor antagonist, M40 (1.5 or 5 nmol), completely blocked feeding induced by MA (68 mg/kg). The effect of the M40 appeared to be specific for MA-induced feeding, since M40 did not significantly attenuate either feeding induced by the antimetabolic glucose analog, 2-deoxy-D-glucose (2DG, 100 or 200 mg/kg), or deprivation-induced water intake. Results suggest that feeding induced by decreased fatty acid oxidation relies upon galaninergic terminals in the hindbrain. Furthermore, results indicate that hindbrain neurons involved in MA-induced feeding differ neurochemically from those important for 2DG-induced feeding.

Mental health. The nurse's support role

The role of the nurse in the management and treatment of manic depression comprises social, psychological and pharmacological interventions. Achieving a balance is crucial to the management of this serious disorder and nurses are ideally placed to help in this.

A model of clinical supervision for nurses undertaking short placements in mental health care settings

This paper presents a model of supervision developed from the experience of supervising undergraduate general nursing students undertaking clinical experience in psychiatric wards. Supervision structures and methods are presented and the theoretical under-pinnings of the supervision model are discussed. Our experience of using the model over the past 5 years suggests that it has the potential to allow students to gain a good understanding of individual patients within a short time span and to engage with them as active collaborators in care. The supervision model can also assist students to develop the knowledge and insights needed to gain the respect of senior colleagues, and the confidence to challenge the professional conservatism that often characterizes psychiatric wards.

Intraventricular glucose blocks feeding induced by 2-deoxy-D-glucose but not mercaptoacetate

Previous results have shown that IV infusion of glucose reduces feeding induced by systemic administration of 2-deoxy-D-glucose (2-DG) or 2-mercaptoacetate (MA) in rats. Because glucose is a metabolic substrate for both central and peripheral tissues, the suppression of feeding by glucose could result from either a central or peripheral metabolic effect. In the present experiment we attempted to clarify the mechanism of glucose-induced suppression of feeding induced by 2-DG and MA by administering glucose centrally during systemic metabolic challenge. Administration of glucose into the lateral ventricle was begun immediately after systemic injection of 2-DG or MA and continued intermittently during the 2-h feeding test. We found that central glucose administration significantly reduced 2-DG- but not MA-induced feeding. These results suggest that the central effects of glucose are sufficient to suppress feeding induced by systemic 2-DG and support the hypothesis that receptors responsible for 2-DG-induced feeding are located in the brain.

Comparison of chromosomal damage induced by X-rays and Ar ions with an LET of 1840 keV/micrometer in G1 V79 cells

Synchronous V79 Chinese hamster cells were exposed in G1 to either X-rays or 4.6 MeV/u Ar-ions (LET = 1840 keV/micrometer) and the induction of chromosomal damage was measured at five sampling times ranging from 14 to 30 h after treatment. To distinguish between cells in the first and second post-irradiation cycle the fluorescence-plus-Giemsa technique was applied. The experiment showed that the time-course of the appearance of damaged cells was markedly influenced by radiation-induced cell cycle delays and depended on both radiation quality and dose. The yield of aberrant metaphases and the number of aberrations per metaphase was found to increase with sampling time, but this increase was more pronounced for Ar ions. These differences in yield-time profiles of X-ray and Ar ion induced chromosomal damage are particularly important for an accurate determination of the RBE for particles. Our data clearly indicate that meaningful RBEs can only be obtained if chromosomal damage is analysed at several post-irradiation sampling times and the complete time-course of the expression of chromosomal damage is taken into account. Besides these quantitative differences, differences in the spectrum of chromosomal lesions were observed for X-rays and Ar ions. Following particle exposure more breaks and less exchange-type aberrations were formed compared with X-irradiation and, despite irradiation in G(1), a significant number of chromatid-type aberrations occurred in Ar-irradiated samples. The experimental results are interpreted on the basis of the different pattern of energy deposition by sparsely and densely ionizing radiation. In addition, a statistical analysis based on the Neyman type A distribution is performed, which takes into account the specific stochastic properties of particle irradiation.

2-Deoxy-D-glucose but not 2-mercaptoacetate increases Fos-like immunoreactivity in adrenal medulla and sympathetic preganglionic neurons

2-Deoxy-D-glucose (2DG) and 2-mercaptoacetate (MA) are drugs that competitively inhibit metabolism of glucose and fatty acids, respectively. Both 2DG and MA stimulate food intake. In addition, 2DG-induced glucoprivation is a known stimulus for adrenomedullary secretion. However, very little is known about the effects of MA on the sympathoadrenal system. In the present study, we examined effects of 2DG and MA on the activity of preganglionic neurons and the adrenal medulla, as indicated by expression of Fos-like immunoreactivity (Fos-li). 2DG, MA, or saline was administered using a stress-attenuated paradigm incorporating remote drug infusion. Expression of Fos-like immunoreactivity (Fos-li) was subsequently examined in the adrenal medulla and in preganglionic sympathetic neurons throughout the intermediolateral column (IML) of the thoracic and lumbar spinal cord. We found that 2DG increased Fos-li in the adrenal medulla and in the IML primarily at spinal cord segments T7-T10, where adrenomedullary preganglionic neurons reside. In contrast, MA did not induce Fos-li either in the adrenal medulla or in sympathetic preganglionic neurons at any cord level. Results support the hypothesis that decreased fatty acid oxidation is not a stimulus for adrenal medullary secretion and provide evidence for a highly selective stimulation of adrenal medullary preganglionic neurons by 2DG.

Mercaptoacetate-induced feeding is impaired by central nucleus of the amygdala lesions

Systemic administration of mercaptoacetate (MA) blocks beta oxidation of fatty acids and stimulates food intake. The present experiment examined MA-induced feeding in rats with bilateral lesions of the central nucleus of the amygdala (CNA) and sham-operated controls. Food intake was measured for 6 h immediately following i.p. injection of 400, 600, or 800 mumol/kg of MA or saline. Feeding was also measured in these rats in response to 2-deoxy-D-glucose (2DG) (100, 200, and 300 mg/kg, SC), a glucose analogue that competitively inhibits glucose utilization. We found that CNA lesions blocked feeding in response to all three doses of MA. Feeding in response to 2DG was significantly reduced, but not abolished, by the lesion. These findings suggest that the CNA is a crucial component of the neural pathway for feeding in response to MA and may also participate in 2DG-induced feeding.

Octanol/water partition coefficients for environmentally important organic compounds : Test of three RP-HPLC-methods and new experimental results

Partition coefficients PO,w ((i)) describing the distribution of a solute i onto coexisting phases of 1-octanol and water are needed in a large variety of applications. They can be measured directly by HPLC as long as log PO,w ((i))≧ 3.5. For more hydrophobic substances, several experimental procedures have been proposed in the literature. The reliability of those methods is questionable. Therefore, in the present work, PO,w ((i)) is determined experimentally by three HPLC methods using reversed-phase HPLC [1]. Results from different procedures are compared critically. The method of Braumann [2] proved to be superior over the OECD-guidelines [3]. It was therefore applied to determine octanol/water partition coefficients for 23 substances at 25 °C. For eight of those substances (4-methylindole; 9-(hydroxymethyl)anthracene; N-ethylcarbazol; ethylcyclohexane; trans-2-octene; l,l-dimethyl-(ethy])cyclohexane; heptylbenzene; 4-dodecyl-l,3-benzenediol) no experimentally determined number for PO,w ((i)) has been published before.

Glucose homeostasis and sympathoadrenal activity in mercaptoacetate-treated rats

The effect of the fatty acid oxidation inhibitor, sodium mercaptoacetate (MA, 600 mumol/kg) on peripheral energy substrate metabolism was investigated in rats with permanent heart catheters. Rats were either fed, 48-h food deprived, or exercising for 30 min. Before and after intravenous MA injection, stress-free blood samples were taken for measurement of blood glucose, plasma free fatty acids (FFA), insulin, epinephrine (E), and norepinephrine (NE) concentrations. In fed animals, MA increased blood glucose, plasma FFA, and NE and decreased insulin concentrations. Plasma E levels did not change. In 48-h-deprived animals, MA elevated low baseline glucose concentrations to levels observed in MA-treated fed animals. Plasma insulin concentrations decreased to almost undetectable levels. Plasma catecholamines and FFA were increased compared to fed rats. In exercising rats, MA caused an exaggerated increase of blood glucose and a pronounced reduction of plasma insulin without affecting exercise-induced FFA and catecholamine responses. The data revealed that the mechanisms that regulate blood glucose concentrations during MA treatment are dependent on the nutritional state and ambient energy expenditure.

Purification of a Photosystem II reaction center from a thermophilic cyanobacterium using immobilized metal affinity chromatography

Oxygen-evolving PS II particles from the thermophilic cyanobacterium Synechococcus elongatus are partially purified by centrifugation on a sucrose gradient and are bound to a Chelating Sepharose column loaded with Cu(2+) ions. Bound particles are then transformed into PS II RC complexes by two washing steps. First, washing with a phosphate buffer (pH=6.5) containing 0.02% of SB 12 removes the rest of phycobilins and leaves pure PS II core particles on the column. Second, washing with a phosphate buffer (pH=6.2) containing 0.2 M LiClO4 and 0.05% of DM removes CP 47 and CP 43 and leaves bare PS II RC complexes on the column. These are then eluted with a phosphate buffer containing 1% of dodecylmaltoside (DM). The molar ratio of pigments in the eluate changes with the progress of elution but around the middle of the elution period a nearly stable ratio is maintained of Chl a: Pheo a: Car: Cyt b 559 equal to 2.9: 1: 0.9: 0.8. In these fractions the photochemical separation of charges could be demonstrated by accumulation of reduced pheophytin (ΔA of 430-440 nm) and by the flash induced formation of P680(+) (ΔA at 820 nm). The relatively slow relaxation kinetics of the latter signal (t1/2 ≈ 1 ms) may suggest that in a substantial fraction of the RCs QA remains bound to the complex.

Contaminated collection media as a cause of pseudoinfection

Following the appearance of positive Gram's stains from sterile surgical cases, an investigation was begun. Nonviable but stainable bacteria were found in the gel-based transport media. The use of a cause-and-effect diagram helped to show the numerous items that affected the problem.

Influence of radiation quality on the expression of chromosomal damage

The amount of chromosomal damage induced in synchronous V79 cells by either 250 kV X-rays or 4.6 MeV/u Ar ions (LET: 1850 keV/microns) was determined at five successive sampling times. The experiments show that the time course of the appearance of damaged cells is strongly influenced by radiation-induced cell cycle perturbations and mitotic delay and depends on radiation quality and dose. The yield of chromosomal damage was found to increase with sampling time, but this increase was more pronounced for Ar ions. Because of the observed differences in the yield time profiles induced by sparsely and densely ionizing radiation the contribution of each sample to the overall damage was considered, i.e. the total (time integrated) amount of damage was determined. The obtained data are interpreted in terms of differences in the spatial energy deposition by sparsely and densely ionizing radiation.