Autoradiography In Animals Research Articles

Assessment of Neuropsychiatric Adverse Events in Influenza Patients Treated with Oseltamivir

After reports from Japan of neuropsychiatric adverse events (NPAEs) in children taking oseltamivir phosphate (hereafter referred to as oseltamivir [Tamiflu; F. Hoffmann-La Roche Ltd, Basel, Switzerland]) during and after the 2004--5 influenza season, Roche explored possible reasons for the increase in reporting rate and presented regular updates to the US FDA and other regulatory authorities. This review summarizes the results of a comprehensive assessment of the company's own preclinical and clinical studies, post-marketing spontaneous adverse event reporting, epidemiological investigations utilizing health claims and medical records databases and an extensive review of the literature, with the aim of answering the following questions: (i) what the types and rates of neuropsychiatric abnormalities reported in patients with influenza are, and whether these differ in patients who have received oseltamivir compared with those who have not; (ii) what levels of oseltamivir and its active metabolite, oseltamivir carboxylate are achieved in the CNS; (iii) whether oseltamivir and oseltamivir carboxylate have pharmacological activity in the CNS; and (iv) whether there are genetic differences between Japanese and Caucasian patients that result in different levels of oseltamivir and/or oseltamivir carboxylate in the CNS, differences in their metabolism or differences in their pharmacological activity in the CNS. In total, 3051 spontaneous reports of NPAEs were received by Roche, involving 2466 patients who received oseltamivir between 1999 and 15 September 2007; 2772 (90.9%) events originated from Japan, 190 (6.2%) from the US and 89 (2.9%) from other countries. During this period, oseltamivir was prescribed to around 48 million people worldwide. Crude NPAE reporting rates (per 1,000,000 prescriptions) in children (aged < or =16 years) and adults, respectively, were 99 and 28 events in Japan and 19 and 8 in the US. NPAEs were more commonly reported in children (2218 events in 1808 children aged < or =16 years vs 833 in 658 adults) and generally occurred within 48 hours of the onset of influenza illness and initiation of treatment. After categorizing the reported events according to International Classification of Diseases (9th edition) codes, abnormal behaviour (1160 events, 38.0%) and delusions/perceptual disturbances (661 events, 21.7%) were the largest categories of events, and delirium or delirium-like events (as defined by the American Psychiatric Association) were very common in most categories. No difference in NPAE reporting rates between oseltamivir and placebo was found in phase III treatment studies (0.5% vs 0.6%). Analyses of US healthcare claims databases showed the risk of NPAEs in oseltamivir-treated patients (n = 159,386) was no higher than those not receiving antivirals (n = 159,386). Analysis of medical records in the UK General Practice Research Database showed that the adjusted relative risk of NPAEs in influenza patients was significantly higher (1.75-fold) than in the general population. Based on literature reports, NPAEs in Japanese and Taiwanese children with influenza have occurred before the initiation of oseltamivir treatment; events were also similar to those occurring after the initiation of oseltamivir therapy. No clinically relevant differences in plasma pharmacokinetics of oseltamivir and its active metabolite oseltamivir carboxylate were noted between Japanese and Caucasian adults or children. Penetration into the CNS of both oseltamivir and oseltamivir carboxylate was low in Japanese and Caucasian adults (cerebrospinal fluid/plasma maximum concentration and area under the plasma concentration-time curve ratios of approximately 0.03), and the capacity for converting oseltamivir to oseltamivir carboxylate in rat and human brains was low. In animal autoradiography and pharmacokinetic studies, brain : plasma radioactivity ratios were generally 20% or lower. Animal studies showed no specific CNS/behavioural effects after administration of doses corresponding to > or =100 times the clinical dose. Oseltamivir or oseltamivir carboxylate did not interact with human neuraminidases or with 155 known molecular targets in radioligand binding and functional assays. A review of the information published to date on functional variations of genes relevant to oseltamivir pharmacokinetics and pharmacodynamics and simulated gene knock-out scenarios did not identify any plausible genetic explanations for the observed NPAEs. The available data do not suggest that the incidence of NPAEs in influenza patients receiving oseltamivir is higher than in those who do not, and no mechanism by which oseltamivir or oseltamivir carboxylate could cause or worsen such events could be identified.

Imaging macrophages and the apoptosis of granulocytes in a rodent model of subacute and chronic abscesses with radiolabeled monocyte chemotactic peptide-1 and annexin V.

Monocytes/macrophages (Mphis), the predominant cell types in subacute and chronic inflammation, are attracted to and activated by monocyte chemotactic peptide-1 (MCP-1). Mphis promote the resolution of inflammation through the induction of apoptosis and phagocytosis of senescent (spent) and bystander (superfluous) granulocytes. We wished to determine whether MCP-1, which selectively binds to Mphis, could be used to image subacute and chronic inflammation. We also sought to image granulocyte apoptosis within these lesions with technetium-99m labeled annexin V, a marker of apoptotic cells. Sterile inflammation was induced in 45 12-week-old male Sprague-Dawley rats by deep intramuscular injection of turpentine into the right thigh. Groups of four to six animals were then imaged 1 h after tail vein injection of 37-148 MBq (1-4 mCi) of 99mTc-labeled MCP-1 or annexin V 1-14 days after turpentine treatment. Image analysis showed significantly greater activity of both MCP-1 and annexin V in inflamed thighs than in control thighs (165%-290% and 188%-313%, respectively; P<0.01) on days 1-5 after turpentine injection. Dual autoradiography in animals co-injected with iodine-125 labeled bovine serum albumin on days 1 and 4 showed specific location of MCP-1 to infiltrating Mphis while annexin V localized to focal zones of apoptosis within granulocytic infiltrates adjacent to abscess cavities. Scintillation well counting on day 5 demonstrated significantly higher (P<0.005) ratios of abscess to control thigh specific activities for MCP-1 (5.83+/-2.17) and annexin V (9.24 +/- 2.8) as compared to 125I-labeled bovine serum albumin (3.11 +/- 0.65). No significant increases in uptake were noted at imaging or ex vivo analyses on days 13 and 14, when lesions were predominately fibrotic. It is concluded that 99mTc-labeled MCP-1 and 99mTc-labeled annexin V both localize in zones of subacute inflammation, reflecting the density of Mphis and the incidence of apoptotic granulocytes, respectively. These agents may be useful in the characterization of subacute inflammation.

Gonadal steroid control of preprocholecystokinin mRNA expression in the limbic‐hypothalamic circuit: Comparison of adult with neonatal steroid treatments

The neuropeptide cholecystokinin (CCK) is involved in the regulation of female, but not male, reproductive behavior. In both sexes, estrogen regulates the expression of CCK in adulthood within the bed nucleus of the stria terminalis and medial amygdaloid nucleus. These areas are parts of an interconnected limbic system-hypothalamic circuit, the development of which is influenced by estrogen during the early postnatal period. This is the same period during which central nervous system (CNS) expression of CCK is dramatically increased, suggesting that the male and female patterns of CCK expression may be the result of early postnatal exposure to estrogen. In the present experiment, the expression of preprocholecystokinin (pCCK) mRNA was determined by in situ hybridization with an isotopically labeled pCCK complementary RNA and emulsion autoradiography in animals whose neonatal and adult gonadal steroid levels had been manipulated. The number of pCCK-expressing cells in animals that were gonadectomized as adults was determined by neonatal estrogen, but stimulation with steroids in adulthood induced a similar number of pCCK-expressing cells in both sexes in the medial amygdala and bed nucleus of the stria terminalis. Neonatal treatment of females with estrogen or testosterone, followed by ovariectomy in adulthood, eliminated the sex difference in pCCK mRNA expression. Males treated neonatally with the aromatase inhibitor androstenedione (to block metabolism of testosterone to estrogen) and orchidectomized in adulthood had a level of pCCK mRNA expression that was similar to that of ovariectomized females. These data suggest that, during neonatal development, estrogen determines the constitutive expression of pCCK mRNA in the medial amygdala and bed nucleus of the stria terminalis, resulting in higher levels of pCCK mRNA expression in males than in females. However, exogenous gonadal steroids induce the same levels of pCCK mRNA expression in adult females, indicating that the levels of gonadal steroids and the patterns of their secretion are the predominant influences on the sexually dimorphic adult levels of pCCK mRNA expression.

Distribution and Elimination of [2-14C]Amino-3, 8-Dimethylimidazo [4, 5-f] quinoxaline in Mice. Analysis by Whole Animal Autoradiography

1. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a potent bacterial promutagen and carcinogen, formed when beef is cooked. In mammals, MeIQx is metabolized and activated by liver enzymes, but induces tumours in both hepatic and extrahepatic tissues. 2. Intravenous administration of [14C]MeIQx and whole animal autoradiography has been employed to examine the disposition of MeIQx. Within 10 min, radiolabel was distributed throughout body tissue. Liver levels of radioactivity rapidly rose and remained elevated in comparison to other tissues, throughout the period of study (4 d). 3. At early time points radioactivity accumulated in the stomach, kidney and salivary glands then later in the intestine. Radioactivity was rapidly eliminated from the majority of tissues although did persist in liver and intestines throughout the duration of the study, probably due to covalently bound material. No radioactivity could be detected in the central nervous system, thus neither MeIQx nor its metabolites cross the blood-brain barrier to any significant extent. 4. The rapid elimination of radioactivity from the tissues is in good agreement with the time course of excretion of MeIQx. Irrespective of the route of administration (i.v., i.p., p.o.), a substantial proportion of the labelled material is excreted within 24 h and is present in both urine and faeces in similar quantities. 5. Thus MeIQx is extensively bioavailable, is distributed throughout body tissue and, although the majority is quickly cleared, some remains bound to liver and intestine.

Chapter 30 Attempts to visualize nicotinic receptors in the brain of monkey and man by positron emission tomography

This chapter investigates the nicotinic receptors in the brain of monkey and man by positron emission tomography. The topographic distribution and the biochemical characteristics of these receptors is investigated by autoradiography in animals. The cholinergic nicotinic receptors appear, perhaps to a greater extent than other receptors, to be characterized by heterogeneity, diversity and plasticity which may be brought about through different combinations of receptor subunits. By use of positron emission tomography (PET) it has now become possible to visualize receptor binding in the brain in vivo. By labeling specific ligands with positron emitting radionuclides such as 11 C or 18 F, images of different neuroreceptor populations can be obtained from living animals or human subjects. Thus the technique contains a great potential for further research in psychopharmacology and neuropathology. The first attempt to visualize central nicotine receptors in vivo by use of PET was done in monkeys. Nine female Rhesus monkeys (6 - 10 kg) were anesthetized with 100 mg of ketamine and 50- 100 mg of diazepam. The animal was positioned in the positron emission tomography, so that the lowest of four horizontal transsections included the cerebellum and the basal parts of the temporal lobes. The present results from PET studies on monkeys and men support the evidence from previous pharmacological and neurophysiological studies that specific nicotinic binding sites are present in the brain. The time course of blood levels of [ 11 C] nicotine and its rapid uptake into the brain were similar in the monkeys and the human subjects.

Modeling metabolic processes in the brain in vivo.

Positron emission tomography provides a means to measure local concentrations of positron-emitters in brain and to reconstruct pictorial images of the distribution of isotope in the brain. This capability is useful when the isotope is confined to a defined chemical species, and its concentration when combined with other measurable variables can be used to assay a physiological or biochemical process. Common variables are concentration and/or specific activity of the precursor tracer molecule in blood or plasma, the kinetics of exchange of the precursor molecule between blood and/or plasma and tissue, and the distribution space of the tracer in the tissue. These variables must be related, usually by an equation based on a kinetic model of the process under study. An example of such a method is the 2-deoxyglucose method which measures local rates of glucose utilization in brain. It was first developed with [14C]deoxyglucose and autoradiography in animals and has demonstrated a close relationship between local functional activity and glucose utilization in brain. It has proved useful to map regions of altered functional activity in the central nervous system in a variety of physiological and pharmacological states. By a combination of this technique with positron emission tomography and the positron-emitting analog, [18F]fluorodeoxyglucose, the method has been adapted for use in humans.

Phagocytose de cellules à cristaux intranucléaires dans l'épithélium de l'intestin moyen de la larve de Tenebrio molitor L.

In the midgut of the larvae of Tenebrio molitor degenerating cells are sometimes engulfed by neighbouring cells. Midgut embryonic cells as well as differentiated cells that contain intranuclear crystals are phagocytosed.Aggregation of chromatin near the nuclear envelope and cytoplasmic condensation are observed in the engulfed cells. Sometimes, the nuclear envelope breaks down; this would explain the nuclear fragmentation and the appearance of chromatin clumps without surrounding envelope in the cytoplasm. The chromatinous nature of these clumps was determined by autoradiography in animals previously injected with tritiated thymidine.In the phagocytosis of cells with intranuclear crystals described in the present paper, the presence of a crystal identifies some intracellular inclusions as ingested cells at a late stage of disintegration.

Cerebral Circulation and Metabolism: A Burgeoning Field of Research

Few journals in recent memory have been initiated under better auspices and more salutary auguries than the Journal of Cerebral Blood Flow and Metabolism. In recent years the field has grown enormously. The elaboration of new techniques, for instance the use of deoxyglucose to study local metabolism, has made a great advance in our understanding of the interactions between cerebral blood flow, cerebral metabolism, and functional events within the central nervous system. The implications of the early studies of cerebral blood flow and oxygen consumption lay in the basic physiological “ 'economy1' of the brain, the precise regulation of its blood flow, the changes which could be measured in normotensive and hypertensive subjects, alterations of the general neuronal milieu, and the effects of pharmacological agents. 3The ability to visualize and measure metabolic activity through autoradiography in animals and emission tomography in man, and the tight coupling between energy metabolism and functional activity, now make it possible to study with high precision and resolution levels of functional activity throughout the brain under a wide variety of physiological and clinical states. Just as the electroencephalograph has had an important impact on neurology and neurosurgery, these techniques will profoundly influence the study of physiological and pathological processes in the brain, providing a new and powerful tool for functional neuroanatomy, for numerous aspects of cerebral physiology, for neurology, psychology, and psychiatry. The Editors of the Journal of Cerebral Blood Flow and Metabolism are to be congratulated for their recognition of the activity in these fields and their anticipation of the widespread research opportunities which lie ahead.

The fate of Tabun in atropine and atropine-oxime treated rats and mice

The influence of TMB-4 and P2S on the metabolism and distribution of intravenously injected 32P-labelled Tabun has been studied in atropinized rats and mice by means of whole animal autoradiography, quantitative determination of 32P and paper chromatography. The largest part of the radioactivity was found in urine; smaller parts were found in faeces and traces in the expired air. In the presence of oximes the amount of 32P excreted increased about 1.5 times. After 24 hr 32P was found in decreasing concentrations in lung, kidney, skeletal bone, liver, heart, skeletal muscle and brain. Tn the presence of P2S the amount of 32P in these tissues decreased to about 50%, while the decrease after TMB-4 was only 10–20% compared with untreated animals. The main metabolite of Tabun was dimethylamino ethoxy hydroxy phosphine oxide. Traces of ethoxy dihydroxy phosphine oxide were noticed in some experiments. In contrast to Tabun, injection of hydrolyzed Tabun produced no accumulation of 32P in the lung.

Uptake and retention of strontium 90 in mouse tissues studied by whole animal autoradiography and impulse counting. I.

The distribution and retention of radiostrontium after a single intraperitoneal injection in mice was investigated by autoradiography and by impulse counting. The technique is described and the findings discussed in detail. (auth)

Uptake and Retention of Strontium 90 in Mouse Tissues Studied by Whole Animal Autoradiography and Impulse Counting. I

Uptake and Retention of Strontium 90 in Mouse Tissues Studied by Whole Animal Autoradiography and Impulse Counting. I