The Birmingham Standardized Idiopathic Intracranial Hypertension Shunt Protocol: Technical Note

BACKGROUND

Insertion of cerebrospinal fluid (CSF) shunts in patients with idiopathic intracranial hypertension (IIH) is challenging mainly due to the small ventricles and phenotypical body habitus. In this report the authors present their surgical protocol for insertion of a ventriculoperitoneal shunt (VPS) in patients with IIH and the associated revision rates.

METHODS

The protocol comprises the following: shunt surgery by neurosurgeons with expertise in CSF disorders; a frontal VPS usually right sided but left sided if the left ventricle is bigger; use of the proGAV 2.0 valve with gravitational unit, set at 10 and the M.scio telemetric sensor; cannulation of the ventricle with StealthStation EM navigation system; and laparoscopic insertion of the peritoneal catheter. The authors describe the protocol and rationale and evidence behind each component and present the results of a prospective analysis on revision rates.

RESULTS

The protocol has been implemented since 1 July, 2019, and by 28 February, 2022, sixty-two patients with IIH had undergone primary VPS insertion. The 30-day revision rate was 6.5%, and overall 11.3% of patients underwent revision during the study period, which compares favorably with the literature. The etiology for early failures was related to the surgical technique.

CONCLUSIONS

The components of the Birmingham standardized IIH shunt protocol are evidence based and address the technical challenges of CSF diversion in patients with IIH. This protocol is associated with a low revision rate, and the authors recommend standardization for CSF shunting in IIH.

Cerebrospinal fluid shunting protocol for idiopathic intracranial hypertension for an improved revision rate

OBJECTIVE

Cerebrospinal fluid (CSF) shunting in idiopathic intracranial hypertension (IIH) is associated with high complication rates, primarily because of the technical challenges that are related to small ventricles and a large body habitus. In this study, the authors report the benefits of a standardized protocol for CSF shunting in patients with IIH as relates to shunt revisions.

METHODS

This was a retrospective study of consecutive patients with IIH who had undergone primary insertion of a CSF shunt between January 2014 and December 2020 at the authors' hospital. In July 2019, they implemented a surgical protocol for shunting in IIH. This protocol recommended IIH shunt insertion by neurosurgeons with expertise in CSF disorders, a frontal ventriculoperitoneal (VP) shunt with an adjustable gravitational valve and integrated intracranial pressure monitoring device, frameless stereotactic insertion of the ventricular catheter, and laparoscopic insertion of the peritoneal catheter. Thirty-day revision rates before and after implementation of the protocol were compared in order to assess the impact of standardizing shunting for IIH on shunt complications.

RESULTS

The 81 patients included in the study were predominantly female (93%), with a mean age of 31 years at primary surgery and mean body mass index (BMI) of 37 kg/m2. Forty-five patients underwent primary surgery prior to implementation of the protocol and 36 patients after. Overall, 12 (15%) of 81 patients needed CSF shunt revision in the first 30 days, 10 before and 2 after introduction of the protocol. This represented a significant reduction in the early revision rate from 22% to 6% after the protocol (p = 0.036). The most common cause of shunt revision for the whole cohort was migration or misplacement of the peritoneal catheter, occurring in 6 of the 12 patients. Patients with a higher BMI were significantly more likely to have a shunt revision within 30 days (p = 0.022).

CONCLUSIONS

The Birmingham standardized IIH shunt protocol resulted in a significant reduction in revisions within 30 days of primary shunt surgery in patients with IIH. The authors recommend standardization for shunting in IIH as a method for improving surgical outcomes. They support the notion of subspecialization for IIH shunts, the use of a frontal VP shunt with sophisticated technology, and laparoscopic insertion of the peritoneal end.

Inhibition by Heparin of Platelet Accumulation In Vivo

In vivo platelet aggregation has been studied using a novel, minimally invasive technique. No aggregatory effects of heparin were observed on normal circulating platelets nor was there enhancement of aggregation of platelets during activation by fhtravenous injection of ADP, collagen, PAF acether or thrombin. On the contrary, high doses of heparin were found to inhibit platelet accumulation induced by ADP, collagen or PAF-acether. Inhibition of these responses necessitated doses of heparin in excess of those required for anti-coagulant effects. The present experiments do not establish a mechanism for such inhibition. Extension to other species, including man, is needed before attributing clinical relevance to the present observations.

Prolongation of Rat Tail Bleeding Time Caused by Oral Doses of a Thromboxane Synthetase Inhibitor Which Have Little Effect on Platelet Aggregation

N (7-carboxyheptyl) imidazole is an inhibitor of platelet thromboxane synthetase that has no effect on the cyclooxygenase activity. An oral dose of the substance to rats (10 mg/kg) prolonged tail bleeding time from 170 ± 13 sec to 284 ± 22 sec. This oral dose also inhibited platelet thromboxane B2 production induced by collagen ex vivo but had little effect on the aggregation dose response curve. There was no effect on thrombin-induced aggregation.

Neither the thrombocytopenia induced by the Arthus reaction nor thrombus formation on an implanted cotton thread were inhibited by oral doses of carboxyheptylimidazole up to 30 mg/kg. Similarly neither the prothrombin nor activated partial thromboplastin time were affected.

It is postulated that this thromboxane synthetase inhibitor prolongs bleeding time not by inhibiting platelet aggregation or blood coagulation but rather by preventing the vasoconstriction which would normally be caused by thromboxane A2.

Acute administration of the small-molecule p75(NTR) ligand does not prevent hippocampal neuron loss or development of spontaneous seizures after pilocarpine-induced status epilepticus

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are initially expressed in a precursor form (e.g., pro-BDNF) and cleaved to form mature BDNF (mBDNF). After pilocarpine-induced status epilepticus (SE), increases in neurotrophins regulate a wide variety of cell-signaling pathways, including prosurvival and cell-death machinery in a receptor-specific manner. Pro-BDNF preferentially binds to the p75 neurotrophin receptor (p75(NTR) ), whereas mBDNF is the major ligand of the tropomyosin-related kinase receptor. To elucidate a potential role for p75(NTR) in acute stages of epileptogenesis, rats were injected prior to and at onset of SE with LM11A-31, a small-molecule ligand that binds to p75(NTR) to promote survival signaling and inhibit neuronal cell death. Modulation of early p75(NTR) signaling and its effects on electrographic SE, SE-induced neurodegeneration, and subsequent spontaneous seizures were examined after LM11A-31 administration. Despite an established neuroprotective effect of LM11A-31 in several animal models of neurodegenerative disorders (e.g., Alzheimer's disease, traumatic brain injury, and spinal cord injury), high-dose LM11A-31 administration prior to and at onset of SE did not reduce the intensity of electrographic SE, prevent SE-induced neuronal cell injury, or inhibit the progression of epileptogenesis. Further studies are required to understand the role of p75(NTR) activation during epileptogenesis and in seizure-induced cell injury in the hippocampus, among other potential cellular pathologies contributing to the onset of spontaneous seizures. Additional studies utilizing more prolonged treatment with LM11A-31 are required to reach a definite conclusion on its potential neuroprotective role in epilepsy.

ProMAT calibrator: A tool for reducing experimental bias in antibody microarrays

Our research group has been developing enzyme-linked immunosorbent assays (ELISA) microarray technology for the rapid and quantitative evaluation of biomarker panels. Studies using antibody microarrays are susceptible to systematic bias from the various steps in the experimental process, and these biases can mask biologically significant differences. For this reason, we have developed a calibration system that can identify and reduce systematic bias due to processing factors. Specifically, we developed a sandwich ELISA for green fluorescent protein (GFP) that is included on each chip. The GFP antigen is spiked into each biological sample or standard mixture and the resulting signal is used for calibration between chips. We developed ProMAT Calibrator, an open-source bioinformatics tool, for the rapid visualization and interpretation of the calibrator data and, if desired, data normalization. We demonstrate that data normalization using this system markedly reduces bias from processing factors. Equally useful, this calibrator system can help reveal the source of the bias, thereby facilitating the elimination of the underlying problem. ProMAT Calibrator can be downloaded at http://www.pnl.gov/statistics/ProMAT .

Increased prevalence of activated CD70+CD4+ T cells in the periphery of patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by loss of immune tolerance. A hallmark of SLE is the presence of autoantibodies resulting from B cell hyperactivity. Previous studies have shown that the presence of abnormal B cell subsets in the periphery, such as CD27highCD20- B cells, correlate with disease activity. We examined the relationship between the expression of CD70, the ligand for CD27 expressed by activated T cells, and indicators of disease activity. A significant increase in median CD70+CD4+ T cell frequencies and memory CD45RA-CD4+ T cell frequencies was observed in SLE samples as compared to healthy controls. The frequencies of CD70+CD4+ T cells correlated with disease duration but not age, treatment, or disease activity. Although a majority of CD70+CD4+ T cells appeared to be effector memory cells, mitogen-stimulated CD70+CD4+ T cells were capable of secreting a full repertoire of effector cytokines. Despite the presence of activated CD4+ T cells, no increase in immunosenescent CD4+ T cells, as defined by the loss of CD28 and/or the acquisition of CD57 was observed in samples from SLE patients. These studies indicate that increased CD70 expression might serve as a useful marker of abnormal T cell activity in SLE.

Decreasing endogenous glucocorticoids alters the ability of bone marrow cells to produce nitric oxide in response to stimulating agents

Glucocorticoids (GC) are essential for the body to maintain homeostasis. Patients with adrenal insufficiencies suffer from numerous health related problems including increased mortality due to sepsis. Here, we examine bone marrow (BM) cells from mice with adrenal insufficiency for their ability to produce nitric oxide (NO). Mice were injected with metyrapone (MR), an agent that selectively blocks glucocorticoid synthesis. BM cells were removed and tested for NO production. The stimulating agents LPS, TNF-alpha, IL-1beta, and IL-4 were all able to synergize with IFN-gamma, stimulating large concentrations of NO compared to normal mice. An important finding is that BM from injected mice produces NO in response to LPS alone, while normal BM cells do not. Experiments with anti IFN-gamma antibody demonstrate that, in MR injected mice, LPS alone stimulated sufficient quantities of IFN-gamma necessary for NO production. Our results demonstrate that reducing GCs alters regulation of NO production by BM cells at several levels.

Activation of bovine peripheral blood gammadelta T cells for cell division and IFN-gamma production

Bovine peripheral blood gammadelta T cells have been evaluated for effector function (IFN-gamma production) and clonal expansion in a variety of systems including following activation by mitogens, IL-12, and stimulation, through the T cell receptor (TCR) with anti-CD3 monoclonal antibody (mAb), a cell-bound molecule and a soluble antigenic extract. To evaluate cell division, carboxyfluorescein succinimidyl ester (CFSE) loading of cells and flow cytometric analysis were used, while IFN-gamma production was evaluated by intracytoplasmic staining. It was found that bovine gammadelta T cells produced IFN-gamma and clonally expanded when stimulated through the TCR/CD3 complex by a cell-associated autologous molecule on monocyte, by bacterial components following in vivo sensitization of gammadelta T cells with a leptospira vaccine or by anti-CD3 mAb. In addition, gammadelta T cells were activated efficiently for effector function but not clonal expansion by culturing with IL-12. In contrast, stimulation by Con A or PMA/ionomycin induced efficient replication but only low level IFN-gamma production which was not enhanced by the presence of IL-12. In several systems the amount of IFN-gamma produced per cell by gammadelta T cells was less than that produced by CD4 T cells in the same cultures.

Origin of the hook effect in extrinsic photoconductors

The response of extrinsic photoconductors to a step change in incident photon flux has long been known to exhibit a sharp transient feature, particularly at higher signal levels, known as the hook effect. We demonstrate experimentally and theoretically that the hook effect can be due to reduced illumination adjacent to the injecting contact. This nonuniformity can be produced by the transverse illumination of the detector that is common for far-infrared Ge:Ga devices. The hook effect has been demonstrated to be either present or absent in the same Ge:Ga photoconductor, at comparable signal size, depending on the nature of the contact illumination. Numerical finite-difference calculations of the transient response support this explanation and produce features that replicate the experimental results.

Ionic mechanisms of GABA-induced long-term potentiation in the rat superior colliculus

GABA-induced excitation and long-term potentiation (LTPG) have been demonstrated recently in the superficial layers of the superior colliculus (SC). In other regions of the nervous system, GABA elicits excitatory responses via ionotropic GABA receptors under certain conditions. This excitation is proposed to be due to either a high neuronal chloride concentration favouring a depolarising chloride efflux, or to a bicarbonate efflux coupled to a chloride influx. The aim of this study was to characterise the mechanisms underlying excitation and prolonged increase in synaptic transmission induced by GABA in the SC. Extracellular field potentials were recorded from 1-month-old rat SC slices, and LTPG of these responses was evoked by application of 3 mM GABA. GABA-induced excitation and LTPG were significantly reduced by lowering the extracellular calcium concentration, but not by a decreased potassium concentration. Replacing the extracellular bicarbonate-buffered perfusion medium with a HEPES-buffered solution had no effect on LTPG but blocking the bicarbonate-generating enzyme carbonic anhydrase both intra- and extracellularly with ethoxyzolamide (50 microM) prevented LTPG. The chloride transport inhibitor bumetanide (50 microM) reduced but did not block LTPG. We therefore suggest that the contribution of the chloride equilibrium to LTPG is only of minor importance. The intracellular bicarbonate pool and related efflux provides the basis for the excitatory action of GABA, leading to a subsequent depolarisation and calcium influx through voltage-dependent calcium channels, thus causing long-lasting changes in synaptic transmission.

Spatial processing in the brain: the activity of hippocampal place cells

The startling discovery by O'Keefe & Dostrovsky (Brain Res. 1971; 34: 171-75) that hippocampal neurons fire selectively in different regions or "place fields" of an environment and the subsequent development of the comprehensive theory by O'Keefe & Nadel (The Hippocampus as a Cognitive Map. Oxford, UK: Clarendon, 1978) that the hippocampus serves as a cognitive map have stimulated a substantial body of literature on the characteristics of hippocampal "place cells" and their relevance for our understanding of the mechanisms by which the brain processes spatial information. This paper reviews the major dimensions of the empirical research on place-cell activity and the development of computational models to explain various characteristics of place fields.

Clinical applications of research on fatigue in children with cancer

Fatigue is a prevalent problem in the pediatric oncology population but is probably under-recognized and undertreated. The research on fatigue in children with cancer presented in this issue offers a welcome exploration of the subject. Clinical nurses must begin to understand the causes and symptoms of fatigue, as well as supportive care measures for their patients. Fatigue can occur in children who receive chemotherapy, radiotherapy, and biotherapy, and in children who are treated with bone marrow transplantation. Education of the patient and family regarding the potential for fatigue is helpful in preparing them for the cancer experience. Factors that contribute to and alleviate fatigue can be identified for each patient, taking into consideration age, developmental level, and cultural background. Parents and patients, especially adolescent patients, may have differing opinions about what fatigue is and what may be helpful. Further research into fatigue in children with cancer is encouraged, especially in patients suffering from alterations in sleep or nutritional status, and in long-term survivors of childhood cancer.

Prenatal choline exposure alters hippocampal responsiveness to cholinergic stimulation in adulthood

Manipulation of dietary choline levels during gestation results in enduring neurobehavioral changes in offspring that last into adulthood. Alterations of hippocampal function and memory are among the most striking changes. Depending upon the measures assessed, prenatal choline supplementation tends to promote excitatory synaptic efficacy in hippocampal circuits while prenatal choline deficiency diminishes it. However, the mechanisms underlying these changes remain unclear. Transverse hippocampal slices were prepared from adult offspring of dams fed choline supplemented, choline deficient, or control diets. We assessed paired-pulse inhibition, and excitatory synaptic responsiveness before and after activation of cholinergic receptors with Carbachol. Prenatally choline deficient animals yielded significantly fewer electrophysiological viable hippocampal slices than did animals from either of the other two treatment groups. Among the slices tested, there were no differences in paired pulse inhibition between the treatment groups. However, transient cholinergic activation resulted in a prolonged enhancement of the amplitude of the population EPSP (pEPSP) response in slices from prenatally choline supplemented animals. These results suggest that GABA receptor-mediated inhibition remains intact after prenatal choline manipulations, and that enhancement of the excitatory responsiveness of hippocampal circuits in slices from prenatally choline supplemented rats may be related in part to an increase in cholinergic tone within the CA1 circuit.

Effects of ethanol on hippocampal place-cell and interneuron activity

Mounting evidence suggests that ethanol exerts effects on learning and memory by altering cellular activity in the hippocampus and related structures. However, little is actually known regarding ethanol's effects on hippocampal function in awake, freely-behaving animals. The present study examines the effects of ethanol on hippocampal place-cell and interneuron activity in freely-behaving rats. Signals from individual hippocampal neurons were isolated while subjects traversed a symmetric Y-maze for food reward. Following 15 min of baseline recording, subjects were injected with one of four doses of ethanol (0.0, 0.5, 1.0 and 1.5 g/kg), and cellular activity was monitored for a 1-h time period. Following sufficient time for recovery (minimum of 3 h post injection), cellular activity was monitored for an additional 15-min period. Both 1.0 and 1.5 g/kg ethanol potently suppressed the firing of hippocampal place-cells without altering place-field locations. Ethanol did not significantly suppress out-of-field firing rates, leading to a decrease in spatial specificity (i.e. the ratio of in-field/out-of-field firing rates). Interneuron activity was not altered by 1.0 g/kg ethanol, but was occasionally suppressed by 1.5 g/kg ethanol. Results are interpreted in light of recent behavioral and electrophysiological studies examining the effects of ethanol on hippocampal function.

Age- and species-dependent maturation of synaptic transmission in the superficial superior colliculus

Both neonatal maturity and postnatal maturation are known to be species dependent. For instance, guinea pigs are born with their eyes open, while eye opening takes place 2 weeks after birth in rats. Moreover, several abnormalities have been observed in albino compared to pigmented species. The pigment melanin is proposed to play a protective role and its absence is thought to contribute to neuronal deficits. In the present study, we aimed to investigate functional differences in synaptic transmission in the visual, superficial layers of the superior colliculus (SC) of albino and pigmented rats and pigmented guinea pigs, at eye opening and 1 month after birth. This was achieved by analysing evoked field excitatory postsynaptic potentials (fEPSPs) in vitro, and by investigating the ability of these responses to express gamma-aminobutyric acid (GABA)-induced long-term potentiation (LTPG), an enduring increase in synaptic efficacy resulting from bath application of GABA. Guinea pigs did not show any obvious differences with respect to overall fEPSP characteristics and synaptic plasticity at both ages studied, indicating that maturation must have occurred prenatally. Rats, however, underwent synaptic maturation and refinement to produce stronger fEPSPs and a more robust level of synaptic plasticity 1 month after birth compared to the conditions at eye opening. The state of pigmentation was found to have a crucial influence, with albino rats showing less enhancement of the strength of synaptic transmission in the SC. It can therefore be concluded that profound developmental differences in pre- and postnatal maturation of the superficial SC exist between guinea pigs and rats, and that the state of pigmentation is a crucial factor in this process.

Binge pattern ethanol exposure in adolescent and adult rats: differential impact on subsequent responsiveness to ethanol

BACKGROUND

Recent evidence indicates that adolescent animals are more sensitive than adults to the disruptive effects of acute ethanol exposure on spatial learning. It is not yet known whether adolescent animals are also more sensitive than adults to the enduring neurobehavioral effects of repeated ethanol exposure. In this study, animals were exposed to ethanol in a binge-pattern during either adolescence or adulthood. At a time when all subjects were adults, spatial working memory was examined in the absence and presence of an acute ethanol challenge.

METHODS

Rats were exposed to ethanol (5.0 g/kg intraperitoneally) or isovolumetric saline at 48 hr intervals over 20 days. Exposure began on either postnatal day 30 (adolescent group) or 70 (adult group). Twenty days after the final injection, a time at which all animals were adults, the subjects were tested on an elevated plus maze and then were trained to perform a spatial working memory task on an eight-arm radial maze. At the beginning of each session of training on the working memory task, subjects retrieved food rewards on four of the eight arms. After a delay, subjects were placed on the maze and allowed to retrieve food from the remaining four arms.

RESULTS

Prior exposure to ethanol did not influence behavior on the plus maze. Performance of the groups did not differ during acquisition of the spatial working memory task with a 5 min delay or during subsequent testing with a 1 hr delay. However, animals treated with ethanol during adolescence exhibited larger working memory impairments during an ethanol challenge (1.5 g/kg intraperitoneally) than subjects in the other three groups.

CONCLUSIONS

The findings indicate that binge pattern exposure to ethanol during adolescence enhances responsiveness to the memory-impairing effects of ethanol in adulthood.

Islet hormones from the African bullfrog Pyxicephalus adspersus (Anura:Ranidae): structural characterization and phylogenetic implications

The African bullfrog Pyxicephalus adspersus is generally classified along with frogs of the genus Rana in the subfamily Raninae of the family Ranidae but precise phylogenetic relationships between species are unclear. Pancreatic polypeptide (PP), insulin, and glucagon-like peptide (GLP-1) were isolated from an extract of P. adspersus pancreas and characterized structurally. A comparison of the amino acid sequence of Pyxicephalus PP (APSEPQHPGG(10)QATPEQLAQY(20)YSDLYQYITF(30)ITRPRF++ +. NH(2)) with those of the known amphibian PP molecules in a maximum parsimony analysis generates a single phylogenetic tree in which Pyxicephalus is the sister to the clade comprising the members of the genus Rana. The three orders of living amphibians form discrete clades with the representative of the Gymnophiona appearing as sister to the Caudata-Anura. In contrast, Pyxicephalus insulin (A chain, GIVEQCCHSA(10)CSLYDLENYC(20)N; B-chain, LANQHLCGSH(10)LVEALYMVCG(20)ERGFFYYPKS(30)) and and GLP-1 (HAEGTFTSDM(10)TSYLEEKAAK(20)EFVDWLIKGR(30)PK) resemble more closely the corresponding peptides from the cane toad Bufo marinus than the peptides from any species of Rana. Cladistic analysis based upon the amino acid sequences of insulin produced a polyphyletic assemblage with the Gymnophiona nesting within an unresolved clade containing the non-ranid frogs. The data support the assertion that the amino acid sequence of PP, but not those of the other islet hormones, is of value as a molecular marker for inferring phylogenetic relationships between early tetrapod species.

Ethanol, memory, and hippocampal function: a review of recent findings

For well over a century, ethanol was believed to exert its effects on cognition and behavior by producing a ubiquitous depression of central nervous system activity. A general disruption in brain function was consistent with the belief that ethanol's effects on cognition and behavior were also quite general. Substantial evidence now indicates that ethanol produces a host of selective effects on neural activity, resulting in regional differences in ethanol's effects in the brain. Consistent with such evidence, recent research suggests that ethanol's effects on cognition and behavior are not as global as previously assumed. The present paper discusses evidence that many of ethanol's effects on learning and memory stem from altered cellular activity in the hippocampus and related structures. Potential mechanisms for ethanol's disruption of hippocampal function are reviewed. Evidence suggests that ethanol disrupts activity in the hippocampus by interacting directly with hippocampal neurons and by interacting with critical hippocampal afferents.

Acute ethanol administration impairs spatial performance while facilitating nonspatial performance in rats

Acute ethanol administration produces learning and memory impairments similar to those found following lesions to the hippocampal system in rats. For example, both ethanol and hippocampal lesions impair performance on spatial learning and memory tasks while sparing performance on many nonspatial learning and memory tasks. Lesions to the hippocampal system can also alter the nature of the information that the animal uses to guide its behavior, from using spatial information to using individual cues. In the present experiment, rats were trained, while sober, to navigate on an eight-arm radial arm maze to a specific arm for food reward. During training, the rewarded arm was always in the same specific location and contained well-defined cues. After the rat learned the task, a memory test was conducted under different doses of ethanol (0.0 g/kg [saline control], 1.0, 1.5, or 2.0 g/kg, intraperitoneal). On the test day the maze was rotated so that the cued arm was 90 degrees to the right of its original position. During testing, intact rats showed a significant bias to approach the place where they had been previously rewarded, even though the cue was no longer located there. Acute ethanol administration dose dependently reduced approaches to the rewarded place. However, ethanol administration did not result in increases in random choices; rather, it resulted in a dose-dependent increase in approaches to the cued arm, now in a new location. These results extend previous research showing that acute ethanol administration and lesions to the hippocampal system produce similar effects on learning and memory in rats.

Placing hippocampal single-unit studies in a historical context

A profound increase in the study of the role of the hippocampus in behavior and cognitive processing resulted from the startling discovery by O'Keefe and Dostrovsky in 1971 that hippocampal neurons fire selectively in different regions or "place fields" of an environment. That discovery spawned a comprehensive theory of hippocampal function that was elucidated in the publication, The Hippocampus as a Cognitive Map by O'Keefe and Nadel in 1978. According to the theory, the hippocampus serves as the neural substrate for maps of allocentric space. The goal of this paper is to revisit the historical background for the development of the cognitive map theory and to examine the context in which the theory and the phenomenon of place field activity began to gain acceptance by the scientific community. While subsequent research has led some to question if the theory can adequately account for all consequences of hippocampal lesions and all the correlates of hippocampal cellular activity, it is clear the theory has stood the test of time and has been successful in generating an enormous amount of fruitful research.

Insulin and proglucagon-derived peptides from the horned frog, Ceratophrys ornata (Anura:Leptodactylidae)

Insulin and peptides derived from the processing of proglucagon have been isolated from an extract of the pancreas of the South American horned frog, Ceratophrys ornata (Leptodactylidae). Ceratophrys insulin is identical to the insulin previously isolated from the toad, Bufo marinus (Bufonidae). Ceratophrys glucagon was isolated in two molecular forms with 29- and 36-amino acid residues in approximately equal amounts. Glucagon-29 is identical to glucagon from B. marinus and from the bullfrog, Rana catesbeiana (Ranidae) and contains only 1 amino acid substitution (Thr29 --> Ser) compared with glucagon from Xenopus laevis (Pipidae). Glucagon-36 comprises glucagon-29 extended from its C-terminus by Lys-Arg-Ser-Gly-Gly-Met-Ser. This extension is structurally dissimilar to the C-terminal octapeptide of mammalian oxyntomodulin and resembles more closely that found in C-terminally extended glucagons isolated from fish pancreata. Ceratophrys glucagon-like peptide-1 (GLP-1) (His-Ala-Asp-Gly-Thr-Tyr-Gln-Asn-Asp-Val10-Gln-Gln-Phe-Leu-Glu- Glu-Lys-Ala-Ala-Lys20-Glu-Phe-Ile-Asp-Trp-Leu-Ile-Lys-Gly- Lys30-Pro-Lys-Lys-Gln-Arg-Leu-Ser) contains 3 amino acid substitutions compared with the corresponding peptide from B. marinus, 8 substitutions compared with GLP-1 from R. catesbeiana, and between 4 and 11 substitutions compared with the three GLP-1 peptides identified in X. laevis proglucagon. GLP-2 was not identified in the extract of Ceratophrys pancreas. The data indicate that, despite its importance in the regulation of glucose metabolism, the primary structure of GLP-1 has been very poorly conserved during evolution, even among a single order such as the Anura.

Anti-inflammatory actions of interleukin-13: suppression of tumor necrosis factor-alpha and antigen-induced leukocyte accumulation in the guinea pig lung

The Th2 cytokine interleukin (IL)-13 is believed to play an important role in the development of allergy, although it has also been ascribed anti-inflammatory roles in several experimental models. In this study, we have examined the effects of human recombinant IL-13 on eosinophilic lung inflammation in the guinea pig. IL-13 (1 to 100 ng, given by intratracheal instillation) did not elicit airway eosinophil recruitment. A pronounced accumulation of eosinophils, as well as monocyte/macrophages, was elicited by intratracheal instillation of guinea pig tumor necrosis factor alpha (gpTNF-alpha). Intratracheal administration of IL-13 (1 to 100 ng) given immediately prior to exposure to gpTNF-alpha resulted in a dose-related suppression of eosinophil and monocyte/macrophage accumulation in the airways, as assessed by bronchoalveolar lavage (BAL) and eosinophil peroxidase activity in whole-lung homogenates. IL-13 treatment also reduced BAL fluid (BALF) leukocyte accumulation induced by subsequent aerosol antigen challenge of sensitized guinea pigs. Antigen challenge also resulted in elevated levels of immunoreactive eotaxin and eosinophil-stimulating activity in BALF, although only the latter was reduced significantly by IL-13 instillation prior to challenge. In contrast to the suppressive effects of IL-13, instillation of human recombinant IL-4 (100 ng) alone elicited an increase in BALF monocyte/macrophage numbers, and IL-4 was unable to inhibit gpTNF-alpha-induced leukocyte accumulation. Hence, IL-13 (but not human IL-4) exhibits an anti-inflammatory action in the airways of gpTNF-alpha- or antigen-challenged guinea pigs, by mechanisms that may involve the decreased generation of eosinophil-stimulating activity in the airways.

Transient behavior of infrared photoconductors: application of a numerical model

A numerical model for the transient response of extrinsic photoconductors is applied to the behavior of Ge:Ga and GaAs:Te detectors. Photoconductors display a two-component response to changes in illumination. The characteristic time and magnitude for the slow component have been studied as a function of background flux, applied field, temperature, device length, and signal size. For large-signal applications, the background flux affects the transient response even when the signal is orders of magnitude greater than the background. Experimental results are presented to support key predictions of the modeling. Because the ratio of fast to slow components is independent of both background and signal size, we propose the operation of detectors in such a way that final signal levels are derived from the fast component.

Spatial performance is more sensitive to ethanol than nonspatial performance regardless of cue proximity

In rodents, ethanol produces a greater impact on the ability to perform spatial reference memory tasks than nonspatial reference memory tasks. Such evidence may reflect a selective disruption in the use of previously acquired spatial information. However, a nonmnemonic explanation has yet to be ruled out Tasks used to study ethanol's effects on spatial memory commonly require subjects to utilize distal, or extramaze, cues to respond correctly. In contrast, many previously used nonspatial tasks could be solved using cues located on the maze itself. Because ethanol has been shown to disrupt sensory processing, it is possible that previously observed differences in the effects of ethanol on spatial and nonspatial performance were actually due to differences in the proximity of relevant cues in the spatial and nonspatial tasks and not to a selective disruption in spatial memory. The present study compares the effects of ethanol on the performance of spatial and nonspatial reference memory tasks that require subjects to discriminate among extramaze cues for correct responding. Subjects were trained while sober to navigate to a goal arm on a 12-arm maze. In the spatial task, the goal arm was defined by its location with respect to a number of extramaze cues. In the nonspatial task, the goal arm was defined by the presence of a single extramaze cue located directly beyond the end of the arm. Subjects were tested under 1 of 4 doses of ethanol (0.0, 0.7, 1.4, and 2.1 g/kg). Performance on the nonspatial task was more resistant to the effects of ethanol than performance on the spatial task. The results suggest that differences in the effects of ethanol on spatial and nonspatial performance are not due to differences in the proximity of relevant cues in previously used spatial and nonspatial tasks.

The effects of MK-801 on spatial working memory and within-session spatial learning

The present study investigated the effects of the NMDA channel blocker MK-801 (0.05, 0.10, and 0.15 mg/kg) on a task that allows for the assessment of both spatial working memory and within-session spatial learning. During the first trial of each day, subjects were shown the spatial location of a food reward on a six-arm radial-arm maze. During nine subsequent free-choice trials, subjects were reinforced for returning to that same spatial location. The location of the food reward varied across days. Thus, choosing correctly on any given trial required subjects to remember where food had been received during the previous trials of that day. The effects of MK-801 on working memory were assessed by analyzing the overall number of errors committed during the nine free-choice trials of each day. The effects of MK-801 on within-session learning were assessed by comparing the number of errors committed during the first three trials of each day to the number of errors committed during the last three trials of each day. Only the highest dose of MK-801 tested (0.15 mg/kg) impaired spatial working memory. No dose of MK-801 impaired the ability of subjects to acquire spatial information within a given session. The failure of MK-801 to impair within-session spatial learning stands in contrast to the well-known effects of MK-801 on spatial learning measured across days. Thus, when coupled with previous research, the findings of the present study further suggest that the NMDA receptor plays a role in the long-term, but not short-term, storage of spatial information.

Comparison between the effects of ethanol and diazepam on spatial working memory in the rat

The present study compared the effects of ethanol and diazepam on a task that allows for the assessment of both spatial working memory and the acquisition of spatial information within each day. During the first trial of each day, subjects were shown the spatial location of a food reward on a six-arm radial-arm maze. During nine subsequent free-choice trials, subjects were reinforced for returning to that same spatial location. The location of the food reward varied across days. Thus, choosing correctly on any given trial required subjects to remember where food had been received during the previous trials of that day. The effects of ethanol and diazepam on working memory were assessed by analyzing the overall number of errors committed during the nine free-choice trials of each day. The effects of ethanol and diazepam on within-day acquisition were assessed by comparing the number of errors committed during the first three trials of each day to the number of errors committed during the last three trials of each day. Ethanol and diazepam both produced dose-dependent increases in working memory errors, and both did so without impairing within-day acquisition. The results of the present study provide further evidence of the similarities between the effects of ethanol and benzodiazepine receptor agonists on learning and memory, and are consistent with the hypothesis that ethanol's potentiation of GABA at GABAA receptors contributes to the learning and memory impairments produced by ethanol.

Large scale identification of genes involved in cell surface biosynthesis and architecture in Saccharomyces cerevisiae

The sequenced yeast genome offers a unique resource for the analysis of eukaryotic cell function and enables genome-wide screens for genes involved in cellular processes. We have identified genes involved in cell surface assembly by screening transposon-mutagenized cells for altered sensitivity to calcofluor white, followed by supplementary screens to further characterize mutant phenotypes. The mutated genes were directly retrieved from genomic DNA and then matched uniquely to a gene in the yeast genome database. Eighty-two genes with apparent perturbation of the cell surface were identified, with mutations in 65 of them displaying at least one further cell surface phenotype in addition to their modified sensitivity to calcofluor. Fifty of these genes were previously known, 17 encoded proteins whose function could be anticipated through sequence homology or previously recognized phenotypes and 15 genes had no previously known phenotype.

Airway inflammation induced by recombinant guinea pig tumor necrosis factor-alpha

We have cloned and expressed recombinant guinea pig tumor necrosis factor-alpha (gpTNF-alpha) and examined its inflammatory activities after tracheal instillation in guinea pigs. A 1,071-bp cDNA, including the region encoding the full-length 234-amino acid gpTNF-alpha protein, was cloned from concanavalin A-stimulated guinea pig splenocytes. The 154-amino acid protein corresponding to secreted gpTNF-alpha was expressed as a fusion protein in Escherichia coli, purified by affinity chromatography, and cleaved to yield a 17-kDa protein. gpTNF-alpha had a cytotoxic effect on WEHI 164 cells and was detected by goat anti-murine tumor necrosis factor-alpha (TNF-alpha) antibody in Western blots. Intratracheal instillation of gpTNF-alpha (50-150 ng) caused pronounced and dose-dependent airway eosinophilia. Incubation of gpTNF-alpha with rabbit anti-murine TNF-alpha sera or heating the gpTNF-alpha before instillation reduced bronchoalveolar lavage (BAL) eosinophils to near control levels. Maximum BAL eosinophilia was observed at 24 h, but eosinophil numbers remained significantly above vehicle-treated animals for 72 h. Hence, gpTNF-alpha elicits a pronounced and protracted eosinophil accumulation in the guinea pig lung.

Recombinant guinea pig and human RANTES activate macrophages but not eosinophils in the guinea pig

To characterize the biologic activities of potential mediators of allergic inflammation, we have cloned, expressed, and purified guinea pig RANTES (gpRANTES). cDNA for gpRANTES was cloned from Con A-stimulated guinea pig spleen cells. A high level of gpRANTES expression in Escherichia coli was achieved by mutation of a human RANTES (hRANTES) expression construct to obtain a 68-amino acid protein identical with the predicted guinea pig amino acid sequence, assuming an equivalent amino terminus as the human protein. Purified gpRANTES was an effective stimulus of human eosinophils as assessed by increases in intracellular free calcium in fura-2-loaded cells and chemotactic responses in vitro. gpRANTES exhibits similar potency and efficacy to hRANTES. In marked contrast, neither gpRANTES nor hRANTES was able to activate guinea pig peritoneal eosinophils in these assays, even in the presence of IL-5. However, gpRANTES was found to be a potent stimulator of guinea pig peritoneal macrophages. Following tracheal instillation of gpRANTES, a dose-dependent increase in macrophages, but not eosinophils, was observed in gpBAL. Macrophage accumulation was detectable by 6 h and sustained for at least 48 h. These results indicate that RANTES in the guinea pig may have a different cellular selectivity than that described in the human, which may be important in the use of animal models in the analysis of allergic disorders. These selectivities do not appear to be accounted for by differences in guinea pig and human RANTES sequences.

Recombinant guinea pig and human RANTES activate macrophages but not eosinophils in the guinea pig

To characterize the biologic activities of potential mediators of allergic inflammation, we have cloned, expressed, and purified guinea pig RANTES (gpRANTES). cDNA for gpRANTES was cloned from Con A-stimulated guinea pig spleen cells. A high level of gpRANTES expression in Escherichia coli was achieved by mutation of a human RANTES (hRANTES) expression construct to obtain a 68-amino acid protein identical with the predicted guinea pig amino acid sequence, assuming an equivalent amino terminus as the human protein. Purified gpRANTES was an effective stimulus of human eosinophils as assessed by increases in intracellular free calcium in fura-2-loaded cells and chemotactic responses in vitro. gpRANTES exhibits similar potency and efficacy to hRANTES. In marked contrast, neither gpRANTES nor hRANTES was able to activate guinea pig peritoneal eosinophils in these assays, even in the presence of IL-5. However, gpRANTES was found to be a potent stimulator of guinea pig peritoneal macrophages. Following tracheal instillation of gpRANTES, a dose-dependent increase in macrophages, but not eosinophils, was observed in gpBAL. Macrophage accumulation was detectable by 6 h and sustained for at least 48 h. These results indicate that RANTES in the guinea pig may have a different cellular selectivity than that described in the human, which may be important in the use of animal models in the analysis of allergic disorders. These selectivities do not appear to be accounted for by differences in guinea pig and human RANTES sequences.

Nitric oxide-induced mobilization of intracellular calcium via the cyclic ADP-ribose signaling pathway

Cyclic adenosine diphosphate ribose (cADPR) is a potent endogenous calcium-mobilizing agent synthesized from beta-NAD+ by ADP-ribosyl cyclases in sea urchin eggs and in several mammalian cells (Galione, A., and White, A. (1994) Trends Cell Biol. 4, 431 436). Pharmacological studies suggest that cADPR is an endogenous modulator of Ca2+-induced Ca2+ release mediated by ryanodine-sensitive Ca2+ release channels. An unresolved question is whether cADPR can act as a Ca2+-mobilizing intracellular messenger. We show that exogenous application of nitric oxide (NO) mobilizes Ca2+ from intracellular stores in intact sea urchin eggs and that it releases Ca2+ and elevates cADPR levels in egg homogenates. 8-Amino-cADPR, a selective competitive antagonist of cADPR-mediated Ca2+ release, and nicotinamide, an inhibitor of ADP-ribosyl cyclase, inhibit the Ca2+-mobilizing actions of NO, while, heparin, a competitive antagonist of the inositol 1,4,5-trisphosphate receptor, did not affect NO-induced Ca2+ release. Since the Ca2+-mobilizing effects of NO can be mimicked by cGMP, are inhibited by the cGMP-dependent-protein kinase inhibitor, Rp-8-pCPT-cGMPS, and in egg homogenates show a requirement for the guanylyl cyclase substrate, GTP, we suggest a novel action of NO in mobilizing intracellular calcium from microsomal stores via a signaling pathway involving cGMP and cADPR. These results suggest that cADPR has the capacity to act as a Ca2+-mobilizing intracellular messenger.

Reliability of the peabody developmental gross motor scale in children with cerebral palsy

The test/retest, intrarater, and interrater reliability of the Peabody Development Gross Motor Scale (PDGMS) was assessed in 12 children with mild or moderate cerebral palsy. A baseline test was administered, scored, and videotaped by one rater and rescored from the videotape by a second independent rater. In order to minimize the effect of developmental maturation, test/retest correlation coefficients of the tests were performed two weeks apart. The intraclass correlation coefficients ranged from 0.82 to 0.98. For interrater reliability, testing following the same protocol was repeated at 2 weeks, 3 and 6 months. Interrater correlation coefficients (r) ranged from 0.89 to 0.98. Interrater correlation coefficients (ICC) from scoring and later rescoring ten videotapes with the closest and furthest interrater agreement ranged from 0.88 to 0.99. The balance and locomotor skill categories were most responsive for assessing gross motor function in this population. These data support the use of the PDGMS as an assessment tool for children with cerebral palsy and the reliability of videotaping assessments.

Parental concerns following a child's discharge from a bone marrow transplant unit

The purpose of this descriptive study was to explore the concerns of parents following a child's discharge from a bone marrow transplant unit. A qualitative approach which included components of grounded theory was used to explore the posttransplant experience from the parents' perspective. Seven parents of five children who were transplanted for a variety of malignancies at a number of out-of-state centers were interviewed about their experiences. Chart analysis and participant observation provided additional sources of data. Initial coding of audio-taped interviews revealed 32 topics of concern voiced by the parents. Use of the constant comparative analysis technique resulted in the emergence of six major themes of the posttransplant experience. The Return Home, Changing Relationships, Working with This, Learning the Rules, The New Norm, and The Uncertain Future were components of this transitional period for each family. Similarities were found between the experiences of study parents and the parents of chronically ill children and parents or spouses of organ transplant recipients. Awareness of posttransplant concerns may facilitate the efforts of both transplant and referral center staff to educate, support, and care for these children and their families.

Cyclic ADP-ribose-induced Ca2+ release from rat brain microsomes

Cyclic ADP-ribose (cADPR), an endogenous NAD+ metabolite in many mammalian and invertebrate tissues, is a potent mediator of calcium mobilization in sea urchin eggs. Our results show that cADPR also stimulates calcium release from rat brain microsomes, marked release occurring over the concentration range 10-250 nM. This is not inhibited by concentrations of heparin which completely abolish inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release. Ryanodine (100 microM) inhibits the cADPR response. Our results are consistent with cADPR being an endogenous messenger mediating Ca2+ release from ryanodine-sensitive pools in brain.

Comparison of Ins(1,4,5)P3 receptors from rat cerebellum and bovine adrenal cortex

Ins(1,4,5)P3 receptors in adrenal cortical and cerebellar membranes can be distinguished by their affinities for Ins(1,4,5)P3 as well as the potencies with which heparin and Mg2+ inhibit binding. We have found that the differences in Ins(1,4,5)P3 affinity and heparin inhibition are maintained upon receptor solubilization and purification. In contrast to this, heparin-agarose affinity purification of solubilized cerebellar receptors reduces the potency of Mg2+ inhibition to that in adrenal cortex. These results suggest that Ins(1,4,5)P3 receptors in adrenal cortex are structurally distinct from those in cerebellum. Monoclonal antibodies raised against C- and N-terminal regions of mouse cerebellar Ins(1,4,5)P3 receptors recognize 250-300-kDa proteins in both rat cerebellum and bovine adrenal cortex.

Two tRNA gene clusters associated with rRNA operons rrnD and rrnE in Bacillus subtilis

Sequence analysis of cloned rescued DNA fragments from a Bacillus subtilis strain with an inserted recombinant plasmid in ribosomal operon rrnE revealed the presence of two tRNA genes for Met and Asp at the 3' end of the operon. Probing chromosomal DNA from a strain carrying a plasmid inserted in rrnD with a fragment containing the genetically unassigned cluster of 16 tRNA genes revealed that the cluster is located immediately following the rrnD operon. Our findings show that all 10 rrn operons in B. subtilis are associated with tRNA gene clusters.