Treatment of medial condylar fractures of the third metatarsus in three horses with fibreglass casts under standing neuroleptanalgesia.

Minimally displaced condylar fractures propagating into the third metatarsal diaphysis were treated conservatively in one thoroughbred and two Arabian racehorses. In each case a neuroleptanalgesic protocol provided adequate pain relief for a rigid fibreglass cast to be applied in a weight-bearing position. The fractures healed completely and the three horses recovered uneventfully. Two of them returned successfully to racing and the third was used for breeding.

The role of human drug self-administration procedures in the development of medications.

The purpose of this review is to illustrate the utility and value of employing human self-administration procedures in medication development, including abuse liability assessments of novel medications and evaluation of potential pharmacotherapies for substance use disorders. Traditionally, human abuse liability testing has relied primarily on subjective reports describing drug action by use of questionnaires; similarly, drug interactions between putative treatment agents and the drugs of abuse have relied on these measures. Subjective reports are highly valued because they provide qualitative and quantitative information about the characteristics of central and peripheral pharmacodynamic effects as well as safety and tolerability. However, self-administration procedures directly examine the behavior of interest-that is, drug taking. The present paper (1) reviews the most commonly used human self-administration procedures, (2) discusses the concordance of subjective reports and self-administration within the context of medications development for substance use disorders, focusing primarily on illustrative examples from development efforts with opioid and cocaine dependence, and (3) explores the utility of applying self-administration procedures to assess the abuse liability of novel compounds, including "abuse-deterrent" formulations (ADFs). The review will focus on opioid and cocaine dependence because a rich database from both clinical laboratory and clinical trial research exists for these two drug classes. The data reviewed suggest that drug-induced changes in self-administration and subjective effects are not always concordant. Therefore, assessment of self-administration in combination with subjective effects provides a more comprehensive picture that may have improved predictive validity for translating to the clinical setting.

Poster - Thurs Eve-38: CT Imaging in high dose rate brachytherapy for treatment of cervical cancer: Estimation of dose to bowel.

Treatment of cervical cancer often involves intracavitary high dose rate (HDR) brachytherapy. Dose delivered to the bladder and rectum are typically estimated using the ICRU reference points. Dose to the sigmoid and small bowel are not estimated, yet these organs typically exhibit significant complication rates. The objective of this study was to estimate dose to the small bowel and sigmoid using CT images. Bladder and rectum dose estimates obtained from the reference point method were also compared to those obtained from CT images. Eighteen CT scans taken before or after treatment of women treated with HDR using ring and tandem applicators were included in this study. The small bowel, sigmoid, bladder and rectum were contoured and the ICRU points were digitized. The minimum dose to 2cc (D2cc ) of each organ was calculated and normalized to % prescribed to Point A. Average D2cc bowel dose was 70%. D2cc bowel dose was significantly higher than both D2cc rectal (27%) and D2cc sigmoid (31%) doses. The average D2cc bladder and rectal doses were 68% (p=NS) and 27% (p<0.001) of prescribed Point A dose. D2cc bowel dose, although significantly higher than rectum and sigmoid, is within an acceptable limit. D2cc bladder and rectum values are either not significantly different from or are significantly lower than ICRU reference values. The results of this study suggest that CT imaging is not necessary for determination of dose to organs at risk. However, image guidance is of value for identifying perforations prior to commencing treatment.

Microvascular injury and blood-brain barrier leakage in Alzheimer's disease.

Thinning and discontinuities within the vascular basement membrane (VBM) are associated with leakage of the plasma protein prothrombin across the blood-brain barrier (BBB) in Alzheimer's disease (AD). Prothrombin immunohistochemistry and ELISA assays were performed on prefrontal cortex. In severe AD, prothrombin was localized within the wall and neuropil surrounding microvessels. Factor VIII staining in severe AD patients indicated that prothrombin leakage was associated with shrinkage of endothelial cells. ELISA revealed elevated prothrombin levels in prefrontal cortex AD cases that increased with the Braak stage (Control=1.39, I-II=1.76, III-IV=2.28, and V-VI=3.11 ng prothrombin/mg total protein). Comparing these four groups, there was a significant difference between control and Braak V-VI (p=0.0095) and also between Braak stages I-II and V-VI (p=0.0048). There was no significant difference in mean prothrombin levels when cases with versus without cerebral amyloid angiopathy (CAA) were compared (p-value=0.3627). When comparing AD patients by APOE genotype (ApoE3,3=2.00, ApoE3,4=2.49, and ApoE4,4=2.96 ng prothrombin/mg total protein) an analysis of variance indicated a difference between genotypes at the 10% significance level (p=0.0705). Tukey's test indicated a difference between the 3,3 and 4,4 groups (p=0.0607). These studies provide evidence that in advanced AD (Braak stage V-VI), plasma proteins like prothrombin can be found within the microvessel wall and surrounding neuropil, and that leakage of the blood-brain barrier may be more common in patients with at least one APOE4 allele.

Whole-body hyperthermia in the rat disrupts the blood-cerebrospinal fluid barrier and induces brain edema.

The present investigation was undertaken to find out whether whole-body hyperthermia (WBH) alters blood-cerebrospinal fluid barrier (BCSFB) permeability to exogenously-administered tracers and whether choroid plexus and ependymal cells exhibit morphological alterations in hyperthermia. Rats subjected to 4 hours of heat stress at 38 degrees C in a biological oxygen demand (BOD) incubator exhibited a profound increase in the BCSFB to Evans blue and radioiodine. Blue staining of the dorsal surface of the hippocampus and caudate nucleus and a significant increase in Evans blue and [131]Iodine in cisternal cerebrospinal fluid were seen following 4-hour heat stress compared to control. Degeneration of choroidal epithelial cells and underlying ependyma, a dilated ventricular space, and degenerative changes in the underlying neuropil were frequent. Hippocampus, caudate nucleus, thalamus, and hypothalamus exhibited profound increases in water content after 4 hours of heat stress. These observations suggest that hyperthermia induced by WBH is capable of breaking down the BCSFB and contributing to cell and tissue injury in the central nervous system.

Atrial natriuretic peptide: its putative role in modulating the choroid plexus-CSF system for intracranial pressure regulation.

Evidence continues to build for the role of atrial natriuretic peptide (ANP) in reducing cerebrospinal fluid (CSF) formation rate, and thus, intracranial pressure. ANP binds to choroid plexus (CP) epithelial cells. This generates cGMP, which leads to altered ion transport and the slowing of CSF production. Binding sites for ANP in CP are plentiful and demonstrate plasticity in fluid imbalance disorders; however, specific ANP receptors in epithelial cells need confirmation. Using antibodies directed against NPR-A and NPR-B, we now demonstrate immunostaining not only in the choroidal epithelium (including cytoplasm), but also in the ependyma and some endothelial cells of cerebral microvessels in adult rats (Sprague-Dawley). The choroidal and ependymal cells stained almost universally, thus substantiating the initial autoradiographic binding studies with 125I-ANP. Because ANP titers in human CSF have previously been shown to increase proportionally to increments in ICP, we propose a compensatory ANP modulation of CP function to down-regulate ICP in hydrocephalus. Further evidence for this notion comes from the current finding of increased frequency of "dark" epithelial cells in CP of hydrocephalic (HTx) rats, which fits our earlier observation that the "dark" choroidal cells, associated with states of reduced CSF formation, are increased by elevated ANP in CSF. Altogether, ANP neuroendocrine-like regulation at CSF transport interfaces and blood-brain barrier impacts brain fluid homeostasis.

Amiodarone inhibits thyroidal iodide transport in vitro by a cyclic adenosine 5'-monophosphate- and iodine-independent mechanism.

Thyroid side effects are common in patients treated for cardiac arrhythmias with amiodarone (AM). A major disturbance is inhibited thyroidal radioiodine uptake in AM-induced thyrotoxicosis, which makes 131I therapy ineffective. On the other hand, failure to escape from the Wolff-Chaikoff effect by down-regulation of the sodium/iodide symporter (NIS) is proposed to explain AM-induced hypothyroidism. However, previously no experimental studies on the possible mechanisms have been conducted. We therefore investigated the early effects of AM on thyroidal iodide transport using bicameral chamber cultures of primary pig thyrocytes that reproduce the three tissue compartments (epithelium, lumen, and extrafollicular space) of the gland. AM dose-dependently (1-50 microm) inhibited the TSH-stimulated transepithelial (basal to apical) transport of 125I- by up to 90%. The inhibitory effect was noticed already after 8 h and was further pronounced after 1-4 d, depending on the AM concentration. The intracellularly accumulated 125I- was reduced by perchlorate but not AM, and quantitative real-time RT-PCR revealed no change in the NIS expression in AM-treated cells. Blocking of cAMP degradation with 3-isobutyl-1-methylxanthine or withdrawal of AM reversed AM-induced changes in electrolyte transport but were unable to recover the suppressed 125I- transport. The iodine-free AM analog dronedarone also inhibited 125I- transport to the same extent as AM. The findings indicate that AM blocks thyroidal iodide uptake by reducing the iodide permeability of the apical plasma membrane of the thyroid epithelial cells. The effect is iodine independent and long-lasting and does not involve impaired function of NIS or the TSH receptor/cAMP signaling pathway.

The prediction of individual differences in response to D-amphetamine in healthy adults.

Based on previous animal work, the present study investigated whether individual differences in motor activity in a novel environment predicted reinforcing and behaviorally activating effects of D-amphetamine (0, 5, 10 and 20 mg p.o.) in healthy adults. When exposed to a novel environment, 18 participants had high levels of motor activity (high responders; HR) and six had low levels (low responders; LR). These group differences were used to predict effects of D-amphetamine on drug reinforcement, salivary cortisol, motor activity, subjective effects, and acoustic startle reflex in subsequent sessions. Unlike observations in rodents, (1). dose-dependent reinforcing effects of D-amphetamine were evident but without group differences; (2). motor activity was greater in HR but did not vary with D-amphetamine dose; and (3). cortisol levels were not related to the reinforcing effects of D-amphetamine. Startle reflex amplitudes were greater in HR following placebo, but D-amphetamine 20 mg equalized this group difference. There was a trend towards less prepulse inhibition of the acoustic startle reflex in HR compared to LR. LR reported greater overall negative effect following amphetamine administration, but this was not consistently related to dose. Finally, participants with high sensation-seeking personality scores exhibited less prepulse inhibition. The results are discussed in terms of the extant literature.

The subjective effects of MDMA and mCPP in moderate MDMA users.

The present study is part of a research program designed to better understand the neurochemical mechanisms underlying the abuse liability of 3,4-methylenedioxymethamphetamine (MDMA) in humans. In these studies, MDMA will be compared to prototypical dopamine (D-amphetamine) and serotonin (meta-chlorophenylpiperazine, mCPP) releasing agents on a variety of measures related to dependence. In order to determine an acceptable dose range (safe but active) of MDMA and mCPP for these studies, moderate MDMA users were administered escalating doses of MDMA (75, 110 and 145 mg/70 kg) and mCPP (17.5, 35 and 52.5 mg/70 kg). Each participant received a single dose under controlled laboratory conditions, i.e. this was a six-group design with a separate group for each dose. There were five participants tested in each group. MDMA increased blood pressure and heart rate whereas mCPP had no effect on these physiological measures. MDMA produced increases in subjective effects indicative of both stimulant (increases in POMS Elation, ARCI Amphetamine, VAS High and Stimulated scale scores) and hallucinogenic effects (increases on five of the six scales of the Hallucinogenic Rating Scale). mCPP produced similar stimulant effects (e.g. increases on POMS Elation, VAS High and Stimulated), as well as hallucinogenic effects (four of the six scales of the Hallucinogenic Rating Scale), which has not been observed in previous studies.

Behavioral measurement of thermal pain sensitivity in humans: effects of stimulus intensity and instructions.

This study validated a human behavioral model of thermal nociception analogous to the rodent tail-flick assay. Effects of instructions and stimulus intensity on behavior (i.e., finger withdrawal latency) were evaluated. Using a repeated measures randomized crossover design, the authors exposed 10 volunteers to varying radiant heat intensities (from 42.2 to 52.2 degrees C) during each of four sessions. In the different sessions, participants were told to remove their finger when they felt heat, felt unpleasant, felt pain, or could no longer tolerate pain. Withdrawal latencies significantly decreased as stimulus intensity increased and significantly increased for sensory, affective, pain, and intolerance instructions. Instruction set differences were significantly larger at higher stimulus intensities. This technique may be useful in human psychopharmacological research.

FGF-2 immunoreactivity in adult rat ependyma and choroid plexus: responses to global forebrain ischemia and intraventricular FGF-2.

Fibroblast growth factor 2 (FGF-2) immunoreactivity (IR) was examined in the ependyma and choroid plexus (CP) of lateral and third ventricles in normal adult rats, as well as in response to transient forebrain ischemia (TFI) and exogenous FGF-2 delivered intraventricularly for several days by osmotic pump. Similar patterns of FGF-2 IR were seen in the CP epithelia of both lateral and third ventricles, as well as in ependymal cells of the third ventricle and along lateral sides of the lateral ventricles. Consistent staining was seen along the apical aspect of epithelial cells facing the cerebrospinal fluid (CSF). Cytoplasmic staining was seen in the absence of ischemia, and was dramatically reduced in response to TFI. FGF-2 treatment followed by TFI resulted in sustained FGF-2 IR within CP and ependymal cells, supporting the idea that these tissues are involved in synthesis and secretion of growth factors into the CSF. In contrast, along the medial sides of the lateral ventricles, adjacent to brain structures such as the hippocampus, consistent staining was seen along the basal aspect of the ependymal cells. We propose that at least some regions of ependyma may function to transport molecules such as FGF-2 directly into the underlying brain parenchyma.

Human choroid plexus growth factors: What are the implications for CSF dynamics in Alzheimer's disease?

The choroid plexus plays a key role in supporting neuronal function by secreting cerebrospinal fluid (CSF) and may be involved in the regulation of various soluble factors. Because the choroid plexus is involved in growth factor secretion as well as CSF dynamics, it is important to understand how growth factors in CSF interact with the brain parenchyma as well as with cells in direct contact with the flowing CSF, i.e., choroid plexus and arachnoid villi. While the existence of growth factors in the choroid plexus has been documented in several animal models, the presence and distribution of growth factors in the human choroid plexus has not been extensively examined. This study describes the general distribution and possible functions of a number of key proteins in the human choroid plexus and arachnoid villi, including basic fibroblast growth factor, FGF receptor, and vascular endothelial growth factor. FGF and VEGF could both be readily demonstrated in choroid plexus epithelial cells. The presence of FGF and VEGF within the choroid plexus was also confirmed by ELISA analysis. Since Alzheimer's disease (AD) is known to be associated with a number of growth factor abnormalities, we examined the choroid plexus and arachnoid villi from AD patients. Immunohistochemical studies revealed the presence of FGF and VEGF within the AD choroid plexus and an increased density of FGFr in both the choroid plexus and the arachnoid villi of AD patients. No qualitative changes in the distribution of FGF and VEGF were observed in the AD choroid plexus. The appearance of FGFr in AD arachnoid was associated with robust amyloid and vimentin immunoreactivity. These findings confirm the presence of FGF and VEGF within the normal and AD choroid plexus and suggest that the alteration of growth factors and their receptors may contribute to the pathogenesis of the hydrocephalus ex vacuo that is characteristically seen in AD.

Discrimination of intranasal cocaine.

In the development of medications for the treatment of cocaine abuse, the drug discrimination paradigm can be used to identify medications that can attenuate the discriminative stimulus effects of cocaine. To ascertain that participants are basing the discrimination on the drug's central effects, this paradigm requires that the drug and placebo administrations do not produce any peripheral effects on which the discrimination can be based. This study examined whether intranasal cocaine (50 mg) can be discriminated from placebo (46 mg lactose + 4 mg cocaine), how quickly this discrimination can be made, and whether pretreatment with intranasal benzocaine can affect this discrimination. Results showed that subjects were generally able to discriminate the drug conditions correctly 15 s after administration, and this was unaffected by benzocaine. These results suggest that subjects base the discrimination on peripheral drug effects (e.g. taste) that are not affected by anaesthesia of the nasal passage, and that the intranasal route of cocaine administration is unlikely to be feasible with a drug discrimination paradigm.

The influence of exchange delays on cigarette versus money choice: a laboratory analog of voucher-based reinforcement therapy.

Contingency-management interventions that provide reinforcement in the form of exchangeable vouchers, contingent on drug abstinence, are among the most effective substance abuse treatment strategies available. Factors known to contribute to the efficacy of these interventions include voucher magnitude and the schedule with which vouchers are made available. Another potential factor may be the delay between earning a voucher and exchanging it for a desired good or service. The authors adapted a laboratory analog of a voucher program to examine the effects of immediacy of reinforcement and its interaction with reinforcer magnitude. Abstinent cigarette smokers made repeated choices between puffs on a cigarette and points worth a variety of monetary values (10 cents-2 dollars). The time at which these points could be exchanged for money varied from the end of the session to 1 or 3 weeks. Results indicated that longer exchange delays and tower magnitude reinforcers increased the number of choices for drug.

Buprenorphine-induced changes in mu-opioid receptor availability in male heroin-dependent volunteers: a preliminary study.

A principle of opioid pharmacotherapy is that high medication doses should occupy fractionally more opioid receptors that mediate heroin effects. In this preliminary study we examined in vivo mu opioid receptor (muOR) binding in three healthy opioid-dependent volunteers during maintenance on 2 and 16 mg sublingual buprenorphine (BUP) liquid, and after detoxification (0 mg) under double-blind, placebo-controlled conditions, and once in matched controls. Binding measures were obtained with the muOR-selective radioligand [11C]carfentanil (CFN) and PET 4 hrs after BUP administration. BUP induced dose-dependent reductions in muOR availability, 36-50% at 2 mg and 79-95% at 16 mg relative to placebo. Heroin abusers also had greater muOR binding potential in the inferofrontal cortex and anterior cingulate regions during placebo, compared to matched controls. Further studies are warranted to examine the relationship of muOR availability with BUP therapeutic actions, and the clinical implications of increased muOR binding during withdrawal.