Localization of hypoxanthine-guanine phosphoribosyltransferase mRNA in the mouse brain by in situ hybridization

Congenital deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) in humans results in a severe neurogenetic disorder known as the Lesch-Nyhan syndrome. Since little information concerning the precise localization of HPRT in the brain is currently available, we have used in situ hybridization to examine the expression of HPRT mRNA in the mouse brain. The results showed that HPRT mRNA is expressed in many regions of the normal mouse brain, with high levels in most, but not all neurons. In contrast, glial cells did not express detectable levels of HPRT mRNA. No HPRT mRNA was detected in the brains of mutant mice carrying a deletion in the HPRT gene.

High efficiency nano-focusing kinoform optics for synchrotron radiation

Modern synchrotron sources have provided for decades intense beams of photons over a large energy spectrum. The availability of improved optics and detectors has opened up new opportunities for the study of matter at the micrometre and nanometre scale in many disciplines. Whilst exploitation of micro-focused beams occurs almost daily in many beamlines, the production of beams of 100 nm is achieved on few instruments which use specialised optics. Refractive lenses, zone plates, curved mirrors, multilayers, and multilayer Laue lenses, can all focus x-rays to less than 50 nm under strict beam stability conditions. Focusing the synchrotron radiation to beam sizes smaller than 10 nm is considered the ultimate goal for the current decade. Silicon micro-technology has so far provided some of the most advanced x-ray refractive lenses; we report on design and characterisation of a novel silicon kinoform lens that is capable of delivering nano-beams with high efficiency.

Characterization of germanium linear kinoform lenses at Diamond Light Source

The unprecedented brilliance achieved by third-generation synchrotron sources and the availability of improved optics have opened up new opportunities for the study of materials at the micrometre and nanometre scale. Focusing the synchrotron radiation to smaller and smaller beams is having a huge impact on a wide research area at synchrotrons. The key to the exploitation of the improved sources is the development of novel optics that deliver narrow beams without loss of brilliance and coherence. Several types of synchrotron focusing optics are successfully fabricated using advanced miniaturization techniques. Kinoform refractive lenses are being developed for hard X-ray beamlines, and the first test results at Diamond are discussed in this paper.

Evaluation of rayon swab surface sample collection method forBacillusspores from nonporous surfaces

AIM

To evaluate US Centers for Disease Control and Prevention recommended swab surface sample collection method for recovery efficiency and limit of detection for powdered Bacillus spores from nonporous surfaces.

METHODS AND RESULTS

Stainless steel and painted wallboard surface coupons were seeded with dry aerosolized Bacillus atrophaeus spores and surface concentrations determined. The observed mean rayon swab recovery efficiency from stainless steel was 0.41 with a standard deviation (SD) of +/-0.17 and for painted wallboard was 0.41 with an SD of +/-0.23. Evaluation of a sonication extraction method for the rayon swabs produced a mean extraction efficiency of 0.76 with an SD of +/-0.12. Swab recovery quantitative limits of detection were estimated at 25 colony forming units (CFU) per sample area for both stainless steel and painted wallboard.

CONCLUSIONS

The swab sample collection method may be appropriate for small area sampling (10 -25 cm2) with a high agent concentration, but has limited value for large surface areas with a low agent concentration. The results of this study provide information necessary for the interpretation of swab environmental sample collection data, that is, positive swab samples are indicative of high surface concentrations and may imply a potential for exposure, whereas negative swab samples do not assure that organisms are absent from the surfaces sampled and may not assure the absence of the potential for exposure.

SIGNIFICANCE AND IMPACT OF THE STUDY

It is critical from a public health perspective that the information obtained is accurate and reproducible. The consequence of an inappropriate public health response founded on information gathered using an ineffective or unreliable sample collection method has the potential for undesired social and economic impact.

SNAP-25 with mutations in the zero layer supports normal membrane fusion kinetics

Considerable data support the idea that intracellular membrane fusion involves a conserved machinery containing the SNARE proteins. SNAREs assembled in vitro form a stable 4-helix bundle and it has been suggested that formation of this complex provides the driving force for bilayer fusion. We have tested this possibility in assays of exocytosis in cells expressing a botulinum neurotoxin E (BoNT/E)-resistant mutant of SNAP-25 in which additional disruptive mutations have been introduced. Single or double mutations of glutamine to glutamate or to arginine in the central zero layer residues of SNAP-25 did not impair the extent, time course or Ca2+-dependency of exocytosis in PC12 cells. Using adrenal chromaffin cells, we found that exocytosis could be reconstituted in cells transfected to express BoNT/E. A double Q→E mutation did not prevent reconstitution and the kinetics of single granule release events were indistinguishable from control cells. This shows a high level of tolerance of changes in the zero layer indicating that the conservation of these residues is not due to an essential requirement in vesicle docking or fusion and suggests that formation of a fully stable SNARE complex may not be required to drive membrane fusion.

Cysteine residues of SNAP-25 are required for SNARE disassembly and exocytosis, but not for membrane targeting

The release of neurotransmitter at a synapse occurs via the regulated fusion of synaptic vesicles with the plasma membrane. The fusion of the two lipid bilayers is mediated by a protein complex that includes the plasma membrane target soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment protein (SNAP) receptors (t-SNAREs), syntaxin 1A and synaptosome-associated protein of 25 kDa (SNAP-25), and the vesicle SNARE (v-SNARE), vesicle-associated membrane protein (VAMP). Whereas syntaxin 1A and VAMP are tethered to the membrane by a C-terminal transmembrane domain, SNAP-25 has been suggested to be anchored to the membrane via four palmitoylated cysteine residues. We demonstrate that the cysteine residues of SNAP-25 are not required for membrane localization when syntaxin 1A is present. Analysis of the 7 S and 20 S complexes formed by mutants that lack cysteine residues demonstrates that the cysteines are required for efficient SNARE complex dissociation. Furthermore, these mutants are unable to support exocytosis, as demonstrated by a PC12 cell secretion assay. We hypothesize that syntaxin 1A serves to direct newly synthesized SNAP-25 through the Golgi transport pathway to the axons and synapses, and that palmitoylation of cysteine residues is not required for targeting, but to optimize interactions required for SNARE complex dissociation.

A novel postsynaptic density protein: the monocarboxylate transporter MCT2 is co-localized with delta-glutamate receptors in postsynaptic densities of parallel fiber-Purkinje cell synapses

Confocal immunofluorescence microscopy showed strong monocarboxylate transporter 2 (MCT2) labeling of Purkinje cell bodies and punctate labeling in the molecular layer. By immunogold cytochemistry, it could be demonstrated that the MCT2 immunosignal was concentrated at postsynaptic densities of parallel fiber-Purkinje cell synapses. The distribution of MCT2 transporters within the individual postsynaptic densities mimicked that of the delta2 glutamate receptor, as shown by use of two different gold-particle sizes. The MCT2 distribution was also compared with the distributions of other monocarboxylate transporters (MCT1 and MCT4). The MCT1 immunolabeling was localized in the endothelial cells, while MCT4 immunogold particles were associated with glial profiles, including those abutting the synaptic cleft of the parallel fiber-spine synapses. The postsynaptic density (PSD) molecules identified so far can be divided into five classes: receptors, their anchoring molecules, molecules involved in signal transduction, ion channels, and attachment proteins. Here, we provide evidence that this list of molecules must now be extended to comprise an organic molecule transporter: the monocarboxylate transporter MCT2. The present data suggest that MCT2 has specific transport functions related to the synaptic cleft and that this transporter may allow an influx of lactate derived from perisynaptic glial processes. The expression of MCT2 in synaptic membranes may allow energy supply to be tuned to the excitatory drive.

Expression and distribution of lactate/monocarboxylate transporter isoforms in pancreatic islets and the exocrine pancreas

Transport of lactate across the plasma membrane of pancreatic islet beta-cells is slow, as described by Sekine et al. (J Biol Chem 269:4895-4902, 1994), which is a feature that may be important for normal nutrient-induced insulin secretion. Although eight members of the monocarboxylate transporter (MCT) family have now been identified, the expression of these isoforms within the exocrine and endocrine pancreas has not been explored in detail. Using immunocytochemical analysis of pancreatic sections fixed in situ, we demonstrated three phenomena. First, immunoreactivity of the commonly expressed lactate transporter isoform MCT1 is near zero in both alpha- and beta-cells but is abundant in the pancreatic acinar cell plasma membrane. No MCT2 or MCT4 was detected in any pancreatic cell type. Second, Western analysis of purified beta- and non-beta-cell membranes revealed undetectable levels of MCT1 and MCT4. In derived beta-cell lines, MCT1 was absent from MIN6 cells and present in low amounts in INS-1 cell membranes and at high levels in RINm5F cells. MCT4 was weakly expressed in MIN6 beta-cells. Third, CD147, an MCT-associated chaperone protein, which is closely colocalized with MCT1 on acinar cell membranes, was absent from islet cell membranes. CD147 was also largely absent from MIN6 and INS-1 cells but abundant in RINm5F cells. Low expression of MCT1, MCT2, and MCT4 contributes to the enzymatic configuration of beta-cells, which is poised to ensure glucose oxidation and the generation of metabolic signals and may also be important for glucose sensing in islet non-beta-cells. MCT overexpression throughout the islet could contribute to deranged hormone secretion in some forms of type 2 diabetes.

Users' Guides to the Medical Literature: XXV. Evidence-based medicine: principles for applying the Users' Guides to patient care. Evidence-Based Medicine Working Group

This series provides clinicians with strategies and tools to interpret and integrate evidence from published research in their care of patients. The 2 key principles for applying all the articles in this series to patient care relate to the value-laden nature of clinical decisions and to the hierarchy of evidence postulated by evidence-based medicine. Clinicians need to be able to distinguish high from low quality in primary studies, systematic reviews, practice guidelines, and other integrative research focused on management recommendations. An evidence-based practitioner must also understand the patient's circumstances or predicament; identify knowledge gaps and frame questions to fill those gaps; conduct an efficient literature search; critically appraise the research evidence; and apply that evidence to patient care. However, treatment judgments often reflect clinician or societal values concerning whether intervention benefits are worth the cost. Many unanswered questions concerning how to elicit preferences and how to incorporate them in clinical encounters constitute an enormously challenging frontier for evidence-based medicine. Time limitation remains the biggest obstacle to evidence-based practice but clinicians should seek evidence from as high in the appropriate hierarchy of evidence as possible, and every clinical decision should be geared toward the particular circumstances of the patient.

The effects of nandrolone decanoate on cocaine-induced kindling in male rats

Use and abuse of various controlled substances in recent years has reached alarming levels. Among these are cocaine and anabolic steroids. The two contrasting types of drug have common sites of action within the limbic system of the central nervous system. The ability of cocaine to provoke seizures is well documented, and sex hormones also have been shown to alter seizure types and characteristics. This project studied the consequences of co-administration of cocaine and a representative anabolic-androgenic steroid, nandrolone decanoate. Specifically, the effects of nandrolone on cocaine-induced kindling of seizures were examined. Nandrolone was shown to increase seizure rate when given in high (20mg twice weekly) intermittent doses. No statistically significant differences were observed with low (2mg) daily doses of nandrolone. The results support the hypothesis that an androgen may interact so as to modify the pattern of cocaine-related kindling. However, the potential of either pharmacodynamic and/or pharmacokinetic mechanism(s) for this interaction exists, and the nature of these interactions remains to be fully elucidated.

GAD levels and muscimol binding in rat inferior colliculus following acoustic trauma

Pharmacological studies of the inferior colliculus (IC) suggest that the inhibitory amino acid neurotransmitter gamma-aminobutyric acid (GABA) plays an important role in shaping responses to simple and complex acoustic stimuli. Several models of auditory dysfunction, including age-related hearing loss, tinnitus, and peripheral deafferentation, suggest an alteration of normal GABA neurotransmission in central auditory pathways. The present study attempts to further characterize noise-induced changes in GABA markers in the IC. Four groups (unexposed control, 0 h post-exposure, 42 h post-exposure, and 30 days post-exposure) of 3-month-old male Fischer 344 rats were exposed to a high intensity sound (12 kHz, 106 dB) for 10 h. Observed hair cell damage was primarily confined to the basal half of the cochlea. There was a significant decrease in glutamic acid decarboxylase (GAD(65)) immunoreactivity in the IC membrane fraction compared to controls (P<0.05) at 0 h (-41%) and 42 h (-28%) post-exposure, with complete recovery by 30 days post-exposure (P>0.98). Observed decreases in cytosolic levels of GAD(65) were not significant. Quantitative muscimol receptor binding revealed a significant increase (+20%) in IC 30 days after sound exposure (P<0.05). These data suggest that changes in GABA neurotransmission occur in the IC of animals exposed to intense sound. Additional studies are needed to determine whether these changes are a result of protective/compensatory mechanisms or merely peripheral differentiation, as well as whether these changes preserve or diminish central auditory system function.

Users' guides to the medical literature: XXIV. How to use an article on the clinical manifestations of disease. Evidence-Based Medicine Working Group

Clinicians rely on knowledge about the clinical manifestations of disease to make clinical diagnoses. Before using research on the frequency of clinical features found in patients with a disease, clinicians should appraise the evidence for its validity, results, and applicability. For validity, 4 issues are important-how the diagnoses were verified, how the study sample relates to all patients with the disease, how the clinical findings were sought, and how the clinical findings were characterized. Ideally, investigators will verify the presence of disease in study patients using credible criteria that are independent of the clinical manifestations under study. Also, ideally the study patients will represent the full spectrum of the disease, undergo a thorough and consistent search for clinical findings, and these findings will be well characterized in nature and timing. The main results of these studies are expressed as the number and percentages of patients with each manifestation. Confidence intervals can describe the precision of these frequencies. Most clinical findings occur with only intermediate frequency, and since these frequencies are equivalent to diagnostic sensitivities, this means that the absence of a single finding is rarely powerful enough to exclude the disease. Before acting on the evidence, clinicians should consider whether it applies to their own patients and whether it has been superseded by new developments. Detailed knowledge of the clinical manifestations of disease should increase clinicians' ability to raise diagnostic hypotheses, select differential diagnoses, and verify final diagnoses. JAMA. 2000;284:869-875

Strengths of composite bonded to base metal alloy using dentin bonding systems

STATEMENT OF PROBLEM

Many different bonding systems are currently available that may be used to bond composite to base metal alloy.

PURPOSE

This study measured and compared bond strengths of composite with a base metal alloy using 8 modern dentin bonding systems.

MATERIAL AND METHODS

Base metal alloy buttons were imbedded in acrylic and ground with 120, 400, and 600 grit sandpaper, respectively. Metal surfaces were air abraded for 5 seconds with 50 microm aluminum oxide, washed for 5 seconds under running tap water, then dried with compressed air. Specimens were arbitrarily divided into 8 groups of 10 specimens. Each group was treated with 1 of 8 dentin bonding regimens. A hybrid composite (Herculite) was placed onto the treated metal surface and light polymerized. Specimens were incubated at 37 degrees C in distilled water for 2 hours. Shear bond strengths were measured and the collected data subjected to an ANOVA, followed by multiple t -tests.

RESULTS

All-Bond 2 exhibited the highest mean shear bond strength and Panavia 21 with primer had the lowest in the tests conducted.

CONCLUSION

All-Bond 2 demonstrated significantly higher shear bond strengths over all materials tested, except 3M Single Bond and Optibond FL. No significant difference was noted between the single component and the multicomponent bonding systems.

CD147 is tightly associated with lactate transporters MCT1 and MCT4 and facilitates their cell surface expression

CD147 is a broadly expressed plasma membrane glycoprotein containing two immunoglobulin-like domains and a single charge-containing transmembrane domain. Here we use co-immunoprecipitation and chemical cross-linking to demonstrate that CD147 specifically interacts with MCT1 and MCT4, two members of the proton-linked monocarboxylate (lactate) transporter family that play a fundamental role in metabolism, but not with MCT2. Studies with a CD2-CD147 chimera implicate the transmembrane and cytoplasmic domains of CD147 in this interaction. In heart cells, CD147 and MCT1 co-localize, concentrating at the t-tubular and intercalated disk regions. In mammalian cell lines, expression is uniform but cross-linking with anti-CD147 antibodies caused MCT1, MCT4 and CD147, but not GLUT1 or MCT2, to redistribute together into 'caps'. In MCT-transfected cells, expressed protein accumulated in a perinuclear compartment, whereas co-transfection with CD147 enabled expression of active MCT1 or MCT4, but not MCT2, in the plasma membrane. We conclude that CD147 facilitates proper expression of MCT1 and MCT4 at the cell surface, where they remain tightly bound to each other. This association may also be important in determining their activity and location.

Abundance and subcellular distribution of MCT1 and MCT4 in heart and fast-twitch skeletal muscles

The expression of two monocarboxylate transporters (MCTs) was examined in muscle and heart. MCT1 and MCT4 proteins are coexpressed in rat skeletal muscles, but only MCT1 is expressed in rat hearts. Among six rat fast-twitch muscles (red and white gastrocnemius, plantaris, extensor digitorum longus, red and white tibialis anterior) there was an inverse relationship between MCT1 and MCT4 (r = -0.94). MCT1 protein was correlated with MCT1 mRNA (r = 0.94). There was no relationship between MCT4 mRNA and MCT4 protein. MCT1 (r = -0.97) and MCT4 (r = 0.88) protein contents were correlated with percent fast-twitch glycolytic fiber. When normalized for their mRNAs, MCT1 but not MCT4 was still correlated with the percent fast-twitch glycolytic fiber composition of rat muscles (r = -0.98). MCT1 and MCT4 were also measured in plasma membranes (PM), triads (TR), T tubules (TT), sarcoplasmic reticulum (SR), and intracellular membranes (IM). There was an intracellular pool of MCT4 but not of MCT1. The MCT1 subcellular distribution was as follows: PM (100%) > TR (31.6%) > SR (15%) = TT (14%) > IM (1.7%). The MCT4 subcellular distribution was considerably different [PM (100%) > TR (66.5%) > TT (36%) = SR (43%) > IM (24%)]. These studies have shown that 1) the mechanisms regulating the expression of MCT1 (transcriptional and posttranscriptional) and MCT4 (posttranscriptional) are different and 2) differences in MCT1 and MCT4 expression among muscles, as well as in their subcellular locations, suggest that they may have different roles in muscle.

Coloboma mouse mutant as an animal model of hyperkinesis and attention deficit hyperactivity disorder

Hyperkinesis and developmental behavioral deficiencies are cardinal signs of attention-deficit hyperactivity disorder. In mice, the mutation coloboma (Cm) corresponds to a contiguous gene defect that results in phenotypic abnormalities including spontaneous hyperactivity, head-bobbing, and ocular dysmorphology. In addition, coloboma mutant mice exhibit delays in achieving complex neonatal motor abilities and deficits in hippocampal physiology, which may contribute to learning deficiencies. The hyperkinesis is ameliorated by low doses of the psychostimulant D-amphetamine and can be rescued genetically by a transgene encoding SNAP-25, located within the Cm deletion. Together with syntaxin and synaptobrevin/VAMP, SNAP-25 constitutes a core protein complex integral to synaptic vesicle fusion and neurotransmitter release. Despite the ubiquitous role of SNAP-25 in synaptic transmission, and uniformly decreased expression in the mutants, coloboma mice show marked deficits in Ca2+-dependent dopamine release selectively in dorsal but not ventral striatum. This suggests that haploinsufficiency of SNAP-25 reveals a specific vulnerability of the nigrostriatal pathway which regulates motor activity and may provide a model for impaired striatal input into executive functions encoded by the prefrontal cortex associated with ADHD.

Botulinum neurotoxin E-insensitive mutants of SNAP-25 fail to bind VAMP but support exocytosis

Neurotransmitter release from synaptic vesicles is mediated by complex machinery, which includes the v- and t-SNAP receptors (SNAREs), vesicle-associated membrane protein (VAMP), synaptotagmin, syntaxin, and synaptosome-associated protein of 25 kDa (SNAP-25). They are essential for neurotransmitter exocytosis because they are the proteolytic substrates of the clostridial neurotoxins tetanus neurotoxin and botulinum neurotoxins (BoNTs), which cause tetanus and botulism, respectively. Specifically, SNAP-25 is cleaved by both BoNT/A and E at separate sites within the COOH-terminus. We now demonstrate, using toxin-insensitive mutants of SNAP-25, that these two toxins differ in their specificity for the cleavage site. Following modification within the COOH-terminus, the mutants completely resistant to BoNT/E do not bind VAMP but were still able to form a sodium dodecyl sulfate-resistant complex with VAMP and syntaxin. Furthermore, these mutants retain function in vivo, conferring BoNT/E-resistant exocytosis to transfected PC12 cells. These data provide information on structural requirements within the C-terminal domain of SNAP-25 for its function in exocytosis and raise doubts about the significance of in vitro binary interactions for the in vivo functions of synaptic protein complexes.

Transgenic rescue of SNAP-25 restores dopamine-modulated synaptic transmission in the coloboma mutant

Many of the molecular components constituting the exocytotic machinery responsible for neurotransmitter release have been identified, yet the precise role played by these proteins in synaptic transmission, and their impact on neural function, has not been resolved. The mouse mutation coloboma is a contiguous gene defect that leads to electrophysiological and behavioral deficits and includes the gene-encoding SNAP-25, an integral component of the synaptic vesicle-docking/fusion core complex. The involvement of SNAP-25 in the hyperactive behavior of coloboma mice, which can be ameliorated by the indirect dopaminergic agonist, amphetamine, has been demonstrated by genetic rescue using a SNAP-25 transgene. Coloboma mice also exhibit increased recurrent inhibition, reduced theta rhythm by tail-pinch and reduced long-term potentiation in the hippocampal dentate gyrus that, as the hyperkinesis seen in these mutants suggests, may reflect impaired monoaminergic modulation. We sought to identify neurophysiological correlates of the rescued hyperactivity within hippocampal synaptic circuitry of SNAP-25 transgenic coloboma mutant mice. In contrast to the differences between coloboma and wild-type mice, there was no significant difference in the duration or amplitude of theta rhythmic activity (4-6 Hz) induced by tail-pinch (10 s), afferent-evoked field potentials, or paired-pulse responses recorded in the dentate gyrus of SNAP-25 transgenic coloboma and wild-type mice. Amphetamine (3.0 mg/kg, i.p.) produced disinhibition of dentate paired-pulse responses in both SNAP-25 transgenic and wild-type mice but increased inhibition in non-transgenic coloboma mice. These findings support the hypothesis that alteration of monoaminergic neurotransmission, which can be reversed by the indirect agonist, amphetamine, is particularly sensitive to alterations in the expression of SNAP-25.

Health care trends, Part I. The promise and perils of evidence-based medicine ... panel discussion

Numerous studies have demonstrated that there are wide variations in the way physicians manage similar patients. This suggests that an evidence-based approach could lead to better outcomes with less cost. But practicing evidence-based medicine requires new skills, such as using computerized databases and applying the rules of evidence to primary and integrative studies in the medical literature. The progress of evidence-based medicine will depend in large measure on how quickly these new skills can be developed and integrated into the practice environment. Here's how six experts see the promise and the perils of evidence-based medicine, now and in the new millennium. Part 2 of the panel discussion will explore the new provider team, which includes nurses and, more recently, pharmacists, who are collaborating with physicians to provide disease management and drugs therapy management services.

Möbius syndrome with oculomotor nerve paralysis without abducens paralysis

Möbius syndrome is typified by bilateral facial nerve palsies, usually with abducens palsies. We examined an infant with Möbius syndrome who had bifacial weakness and third nerve palsies, but intact abduction of both eyes. Lower cranial nerve involvement, leading to respiratory, swallowing, and cardiac difficulties, was also present. Pathologic examination of the brainstem showed absent or hypoplastic third, seventh, tenth, and twelfth nerve nuclei. The fourth, fifth, sixth, and eighth nerve nuclei were intact. In Möbius syndrome with ocular motor palsies, rarely the sixth nerve may be spared.

Lactic acid efflux from white skeletal muscle is catalyzed by the monocarboxylate transporter isoform MCT3

The newly cloned proton-linked monocarboxylate transporter MCT3 was shown by Western blotting and immunofluorescence confocal microscopy to be expressed in all muscle fibers. In contrast, MCT1 is expressed most abundantly in oxidative fibers but is almost totally absent in fast-twitch glycolytic fibers. Thus MCT3 appears to be the major MCT isoform responsible for efflux of glycolytically derived lactic acid from white skeletal muscle. MCT3 is also expressed in several other tissues requiring rapid lactic acid efflux. The expression of both MCT3 and MCT1 was decreased by 40-60% 3 weeks after denervation of rat hind limb muscles, whereas chronic stimulation of the muscles for 7 days increased expression of MCT1 2-3-fold but had no effect on MCT3 expression. The kinetics and substrate and inhibitor specificities of monocarboxylate transport into cell lines expressing only MCT3 or MCT1 have been determined. Differences in the properties of MCT1 and MCT3 are relatively modest, suggesting that the significance of the two isoforms may be related to their regulation rather than their intrinsic properties.

Neonatal alcohol exposure reduces NMDA induced Ca2+ signaling in developing cerebellar granule neurons

Glutamatergic neurotransmission through NMDA receptors is critical for both neurogenesis and mature function of the central nervous system (CNS), and is thought to be one target for developmentally-induced damage by alcohol to brain function. In the current study we examined Ca2+ signaling linked to NMDA receptor activation as a potential site for alcohol's detrimental effects on the developing nervous system. We compared Ca2+ signals to NMDA in granule neurons cultured from cerebella of rat neonates exposed to alcohol (ethanol) during development with responses to NMDA recorded in separated control groups. Alcohol exposure was by the vapor chamber method on postnatal days 4-7. An intermittent exposure paradigm was used where the pups were exposed to alcohol vapor for 2. 5 h/day to produce peak BALs of approximately 320 mg%. Control pups were placed in an alcohol-free chamber for a similar time period or remained with their mother. After culture under alcohol-free conditions for up to 9 days, Ca2+ signaling in response to NMDA was measured using fura-2 Ca2+ imaging. Results show that the peak amplitude of the Ca2+ signal to NMDA was significantly smaller in cultured granule neurons obtained from alcohol-treated pups compared to granule neurons from control pups. In contrast, the Ca2+ signal to K+ depolarization was not depressed by the alcohol treatment. Resting Ca2+ levels were also altered by the alcohol treatment. These results show that intermittent alcohol exposure during development in vivo can induce long-term changes in CNS neurons that affect the Ca2+ signaling pathway linked to NMDA receptors and resting Ca2+ levels. Such changes could play an important role in the CNS dysfunction associated with alcohol exposure during CNS development.

Transient, high levels of SNAP-25 expression in cholinergic amacrine cells during postnatal development of the mammalian retina

In the present study, we have examined the development of cholinergic amacrine cells in the retina of the Brazilian opossum, Monodelphis domestica. An antibody directed against choline acetyltransferase (ChAT) revealed that ChAT-like immunoreactivity (ChAT-IR) was first observed at 15 days postnatal (15PN). By 25PN, ChAT-IR identified two matching populations of amacrine cells in the inner nuclear and ganglion cell layer. Bromodeoxyuridine birth-dating analysis coupled with immunolabeling with the anti-ChAT antibody revealed that the cholinergic amacrine cells are born postnatally, between 2PN and 15PN. In addition, we have examined the differentiation of the cholinergic amacrine cells by using an antibody directed against a presynaptic terminal-associated protein, synaptosomal-associated protein of 25 kDa (SNAP-25). Double-labeling analysis revealed that relatively high levels of SNAP-25-IR were selectively present in cholinergic amacrine cells prior to eye opening. However, in the mature retina, high levels of SNAP-25-IR were no longer observed in the ChAT-IR amacrine cells. These results reveal a distinct period in development, prior to eye opening, when high levels of SNAP-25-IR are selectively expressed in cholinergic amacrine cells. The specificity and time course of the high levels of SNAP-25 in cholinergic amacrine cells may be critical in mediating the transient properties of these cells during visual system development.

T-cell receptor repertoire in matched MART-1 peptide-stimulated peripheral blood lymphocytes and tumor-infiltrating lymphocytes

Characterization of tumor-associated antigens (TAAs) recognized by CTLs makes the consideration of therapeutic strategies based on peptide stimulation of peripheral blood lymphocytes (PBLs) feasible. Several such approaches are adoptive transfer of peptide-stimulated PBLs, ex vivo peptide stimulation of dendritic cells, and direct vaccination with TAA-derived peptides. A critical component of any of these peptide-based strategies is the requirement that the patient's PBLs are able to react productively against the presented TAA. The purpose of this study, through the study of T-cell receptor (TCR) usage, was to evaluate the T-cell response in matched MART-1(27-35) peptide-stimulated PBLs and tumor-infiltrating lymphocytes (TILs). MART-1(27-35)-reactive PBL and TIL cultures were generated from three patients by in vitro stimulation with an immunodominant peptide of MART-1 (MART-1(27-35)). All cultures had a human leukocyte antigen A2-restricted, MART-1(27-35)-specific CTL response. The TCR usage of each was assessed by the DNA sequence analysis of 50 TCR beta clones obtained by rapid amplification of cDNA ends per culture. TCR analysis suggests a TCR repertoire that differed from patient to patient (8-16 subfamilies were used) and a predominant usage of a different variable beta chain (BV) by each of these MART-reactive T cells. These predominant BV rearrangements were derived from multiple clonotypes because different variable, diversity, and junctional regions were observed. However, a similar pattern of expansion was present for both PBLs and TILs; the relative usage of each prevailing BV was more marked in TILs (36, 50, and 78% of TILs versus 26, 20, and 24% of PBLs, respectively), a broader TCR repertoire was used by PBLs (P > 0.05), and similar TCR subfamily usage was noted when TIL and PBL cultures from the same patient were compared (8 of 11, 7 of 9, and 7 of 8 for patients 1, 2, and 3, respectively). Furthermore, the exact same clonotypes derived from predominant TCR subfamilies in the PBLs and TILs were present in each patient, suggesting peptide-stimulated expansion in both biological compartments. These studies suggest that there will not be a limited and predictable TCR subfamily response to a specific TAA, although reproducible patterns of PBL and TIL expansion are present from patient to patient. Additionally, identical T-cell clonotypes having the same potential for antigen-driven expansion were present in a patient's PBLs and TILs. As such, our data support the conceptualization of approaches using adoptive transfer or vaccination based on TAA-derived peptide stimulation of PBLs.

Botulinum neurotoxin types A and E require the SNARE motif in SNAP-25 for proteolysis

Botulinum neurotoxins type A and E (BoNT/A and BoNT/E) are metalloproteases with a unique specificity for SNAP-25 (synaptosome-associated protein of 25 kDa), an essential protein component of the neuroexocytotic machinery. It has been suggested that this specificity is directed through the recognition of a nine residue sequence, termed SNARE motif, that is common to the other two SNARE proteins: VAMP (vesicle-associated membrane protein) and syntaxin, the only known substrates of the other six clostridial neurotoxins. Here we analyse the involvement of the four copies of the SNARE motif present in SNAP-25 in its interaction with BoNT/A and BoNT/E by following the kinetics of proteolysis of SNAP-25 mutants deleted of SNARE motifs. We show that a single copy of the motif is sufficient for BoNT/A and BoNT/E to recognise SNAP-25. While the copy of the motif proximal to the cleavage site is clearly involved in recognition, in its absence, other more distant copies of the motif are able to support proteolysis. Also, a non-neuronal isoform of SNAP-25, Syndet, is shown to be sensitive to BoNT/E, but not BoNT/A, whilst the SNAP-25 isoforms from Torpedo marmorata and Drosophila melanogaster were demonstrated not to be substrates of these metalloproteases.

Differential regulation of genes encoding synaptic proteins by the Oct-2 transcription factor

In order to investigate the effect of the Oct-2 POU family transcription factor on the regulation of genes encoding synaptic proteins, we have used cell lines in which the level of Oct-2 has been greatly reduced using an antisense approach. The reduced Oct-2 level results in enhanced expression of SNAP-25 and synapsin I, indicating that the genes encoding these proteins are normally repressed by Oct-2 in neuronal cells. In contrast, no alteration was observed in the levels of the synaptic proteins, synaptophysin and synaptotagmin. Although the neuronal forms of Oct-2 can repress the synapsin I promoter in co-transfection experiments, indicating that they have a direct effect on the expression of this gene, they have no effect on the activity of the SNAP-25 promoter, indicating that the effect of Oct-2 on this gene is likely to be indirect. These effects are discussed in terms of the differential effect of Oct-2 and the related POU family transcription factor Brn-3a, on the promoters of genes encoding different synaptic proteins.

Characterization of a sustained-release delivery system for combined cytokine/peptide vaccination using a poly-N-acetyl glucosamine-based polymer matrix

Identification of tumor-associated antigens (TAAs) and their class I MHC-restricted epitopes now allows for the rational design of peptide-based cancer vaccines. A biocompatible system capable of sustained release of biologically relevant levels of cytokine and TAA peptide could provide a more effective microenvironment for antigen presentation. Our goal was to test a sustained-release cytokine/TAA peptide-based formulation using a highly purified polysaccharide [poly-N-acetyl glucosamine (p-GlcNAc)] polymer. Granulocyte-macrophage colony-stimulating factor (GM-CSF; 100 microgram) and MART-1(27-35) peptide (128 microgram in DMSO) were formulated into p-GlcNAc. Peptide release was assayed in vitro using interleukin 2 production from previously characterized MART-1(27-35)-specific Jurkat T cells (JRT22). GM-CSF release was assayed via ELISA and proliferation of M-07e (GM-CSF-dependent) cells. Local bioavailability of MART-1(27-35) peptide for uptake and presentation by antigen-presenting cells was demonstrated for up to 6 days (>0.5 microgram/ml). More than 1.0 microgram/ml GM-CSF was concomitantly released over the same period. Biocompatibility and local tissue response to p-GlcNAc releasing murine GM-CSF was determined in C57BL/6 mice via s.c. injection using murine GM-CSF (0. 2 microgram/ml) in 200 microliter of a 2.5% polymer gel. Significant lymphocytic and eosinophilic infiltration was observed 2-7 days after injection with polymer containing murine GM-CSF. The results of our studies show that this biocompatible system is capable of a sustained concomitant release of biologically active peptide and cytokine into the local microenvironment. These findings support further studies to validate a p-GlcNAc delivery system vehicle for a cytokine/TAA peptide-based cancer vaccine.

A single residue within the homeodomain of the Brn-3 POU family transcription factors determines whether they activate or repress the SNAP-25 promoter

The closely related POU family transcription factors Brn-3a and Brn-3b differ in their effect on a number of different neuronally expressed promoters such as that of the gene encoding the synaptic vesicle component SNAP-25. Thus Brn-3a activates these promoters whilst Brn-3b represses both their basal activity and their activation by Brn-3a. We show here that alterations of a single amino acid at position 22 in the POU-homeodomain from the isoleucine found in Brn-3b to the valine found at the equivalent position in Brn-3a converts Brn-3b from a repressor to an activator of the SNAP-25 gene promoter. The converse mutation in Brn-3a abolishes its ability to activate the SNAP-25 gene promoter and allows it to repress the basal activity of the promoter and its activation by wild type Brn-3a. This is the first time that a single amino acid change has been shown to convert an activator of a naturally occurring promoter to a repressor and vice versa. These results are discussed in terms of the critical role of position 22 in the POU homeodomain in the protein-protein interactions of POU proteins.

Efficacy of argon laser trabeculoplasty in aphakic and pseudophakic eyes

BACKGROUND AND OBJECTIVE

This study evaluated the efficacy of argon laser trabeculoplasty (ALT) in patients with aphakia or pseudophakia.

PATIENTS AND METHODS

The authors retrospectively analyzed 63 eyes of 63 patients with aphakia or pseudophakia who had uncontrolled open-angle glaucoma and were treated with 180 degrees or 360 degrees ALT.

RESULTS

The mean intraocular pressure (IOP) before ALT was 25.1 mm Hg (+/- 8.1 mm Hg). Two years after ALT, the mean IOP in the successfully treated group was 15.4 mm Hg. The mean survival time (50% success rate) for all treated eyes was 23 months, and treatment was successful in 34% of eyes at 36 months. Pseudophakic eyes had a better response than aphakic eyes (P = .06), and eyes that had extracapsular surgery did better than eyes with intracapsular surgery (P = .07).

CONCLUSION

ALT in aphakic or pseudophakic eyes with uncontrolled glaucoma is a safe, reasonably effective treatment that can delay the need for trabeculectomy.

Tissue distribution of SNAP-23 and its subcellular localization in 3T3-L1 cells

The SNARE hypothesis of vesicular traffic proposes that three proteins, VAMP/synaptobrevin, syntaxin, and SNAP-25, constitute a complex that docks the vesicle at the target membrane. VAMP and syntaxin isoforms have been identified outside the nervous system, and a cDNA to a SNAP-25 related protein, SNAP-23, was recently identified in human lymphocytes. Here we report the generation of isoform-specific antibodies to SNAP-23 cloned from human melanoma cells, and their use in detecting the expression and localization of the endogenous SNAP-23 protein in several tissues and cell lines. SNAP-23 was readily detected in liver, lung, kidney, and spleen, to a lesser extent in muscle and heart, and was almost undetectable in brain. The protein was also abundant in fibroblast, muscle, and fat cell lines, but relatively less enriched in neuroendocrine PC12 cells. SNAP-23 abundance did not change during differentiation of 3T3-L1 fibroblasts into adipocytes. In both, SNAP-23 was membrane-bound and below detectable levels in the cytosolic fraction. Subcellular fractionation of 3T3-L1 adipocytes revealed that the majority of the protein was associated with plasma membranes. These findings support the conclusion that a tripartite SNARE complex exists outside of the nervous system, and suggest that SNAP-23 may play a role in vesicle traffic in most cell types.

Differential sensitivity of c-Fos expression in hippocampus and other brain regions to moderate and low doses of alcohol

Alcohol consumption in humans is characterized by a wide range of behavioral effects and pathological consequences that suggest several neuroanatomical targets for this drug. To identify these targets we have mapped alcohol-induced changes in the expression of the c-Fos protein in the rat brain. Administration of a moderate dose of alcohol (1.5 g kg-1) led to a suppression of basal and novel environment-induced c-Fos expression in the hippocampus and simultaneous induction of this protein in regions important for the reinforcing as well as aversive properties of drugs. These include the extended amygdala (including the central nucleus of amygdala, bed nucleus of stria terminals and nucleus accumbens), regions processing sensory information (including the Edinger-Westphal nucleus and the paraventricular nucleus of the thalamus) and in stress-related areas (including the paraventricular nucleus of the hypothalamus, nucleus of the solitary tract and several neocortical areas). Repeated administration of the same dose of alcohol did not decrease alcohol-mediated suppression of c-Fos in the hippocampus, but decreased alcohol-induced expression of c-Fos in other areas. A lower dose of acute alcohol (0.5 g kg-1) reduced basal c-Fos expression in several areas of the neocortex, hippocampus and hypothalamus. However, while this low dose of alcohol was unable to counteract the environmental novelty-induced c-Fos expression in these areas, it increased c-Fos expression in the central nucleus of amygdala (an effect similar to the one observed previously for diazepam). Our data suggest that the effects of low doses of alcohol may be due to selective GABA-like effects of ethanol, whereas higher doses of ethanol involve effects on multiple neurotransmitter systems.

Coloboma hyperactive mutant mice exhibit regional and transmitter-specific deficits in neurotransmission

The mouse mutant coloboma (Cm/+), which exhibits profound spontaneous hyperactivity and bears a deletion mutation on chromosome 2, including the gene encoding synaptosomal protein SNAP-25, has been proposed to model aspects of attention-deficit hyperactivity disorder. Increasing evidence suggests a crucial role for SNAP-25 in the release of both classical neurotransmitters and neuropeptides. In the present study, we compared the release of specific neurotransmitters in vitro from synaptosomes and slices of selected brain regions from Cm/+ mice with that of +/+ mice. The release of dopamine (DA) and serotonin (5-HT) from striatum, and of arginine vasopressin and corticotropin-releasing factor from hypothalamus and amygdala is calcium-dependent. Glutamate release from and content in cortical synaptosomes of Cm/+ mice are greatly reduced, which might contribute to the learning deficits in these mutants. In dorsal striatum of Cm/+ mutants, but not ventral striatum, KCl-induced release of DA is completely blocked and that of 5-HT is significantly attenuated, suggesting that striatal DA and 5-HT deficiencies may be involved in hyperactivity. Further, although acetylcholine failed to induce hypothalamic corticotropin-releasing factor release from Cm/+ slices, restraint stress increased plasma corticosterone levels in Cm/+ mice to a significantly higher level than in +/+ mice, suggesting an important role for arginine vasopressin in hypothalamic-pituitary-adrenal axis activation. These results suggest that reduced SNAP-25 expression may contribute to a region-specific and neurotransmitter-specific deficiency in neurotransmitter release.

Adjustable horizontal rectus recession surgery for disparate distance-near ocular deviations

Strabismic deviations which display incomitance changing from distance fixation to near fixation are the result of many disturbances of both the supranuclear and infranuclear ocular motor system. This report details the surgical treatment and outcome of 6 patients with disparate distance-near deviations due to different etiologies. The surgical procedure involves recessing all four horizontal recti on both eyes using the adjustable suture technique. The approach to surgery consisted of operating on the vergence angle with the larger deviation with a bilateral lateral rectus recession (BLREC) or a bilateral medial rectus recession (BMREC) and simultaneously operating on the smaller vergence angle, treating the total induced deviation with the bilateral recession not used first (remaining BLREC or BMREC). All patients had a significant decrease in their distance-near disparity, increased horizontal comitance, normalization of their accommodative convergence to accommodation ratios, and resolution of diplopia. A four horizontal recti muscle, adjustable suture recession is another technique that can be added to the treatment regimens for distance-near disparity strabismic syndromes.

Differential regulation of genes encoding synaptic proteins by members of the Brn-3 subfamily of POU transcription factors

The three members of the Brn-3 subfamily of POU transcription factors have distinct effects on target gene expression. We show that the promoter of the gene encoding the presynaptic nerve terminal protein SNAP-25 resembles previously characterised target genes in being activated by Brn-3a and Brn-3c, but being repressed by Brn-3b. Unlike other target genes, however, the SNAP-25 promoter can be activated by either the N- or C-terminal activation domains of Brn-3a. In contrast to the SNAP-25 gene, the gene encoding the synaptic vesicle protein synapsin 1 is activated by all the Brn-3 factors, the first gene for which this activation pattern has been reported Interestingly, however, similar activation by all three Brn-3 factors can be observed if the SNAP-25 promoter is truncated by removal of sequences from -2200 to -288 relative to the transcriptional start site. Moreover, a region of the SNAP-25 promoter from -283 to -126 can render a heterologous promoter responsive to activation by all three Brn-3 factors. Differences in promoter structure may thus result in differences in the response to different Brn-3 factors, thus allowing these factors to produce diverse activation patterns of neuronally expressed genes, such as those encoding different synaptic proteins.

Long-term follow-up of ocular findings in children with Stickler's syndrome

PURPOSE

To document the longitudinal changes in eye status of children diagnosed with Stickler's syndrome in the first decade of life.

METHOD

All patients with cleft palate were referred for eye examination. Of these, patients with systemic findings of Stickler's syndrome were included in this report.

RESULTS

Thirty-four eyes in 17 patients met inclusion criteria, with median best-corrected recognition acuity of 20/30. The mean cycloplegic refraction at presentation was -5.00 diopters, and the mean refraction at last visit was -5.50 diopters.

CONCLUSIONS

Refractive errors, cataracts, and vitreoretinal abnormalities can be detected early in life in patients with Stickler's syndrome, and refractive error changed little during the follow-up period.