Molecular markers of reactive plasticity

Sprouting has been studied extensively using morphological markers, but relatively little is known regarding the molecular and biochemical events which underlie the sprouting response. Moreover, due to the lack of suitable markers, it has been difficult to examine changes in the major hippocampal pathways in animal lesion models and in neurological disorders. We utilized two markers, obtained through molecular genetic analysis, to examine alterations in hippocampal circuits following partial deafferentation. SNAP-25, a neuronal specific protein, is located presynaptically in the perforant path, Schaffer collaterals, mossy fibers, and commissural/associational pathways. Selective destruction of CA3 pyramidal neurons, dentate gyrus granule cells, and entorhinal cortical neurons resulted in a loss of SNAP-25 immunoreactivity at the site of the axonal projections of the lesioned neurons. SNAP-25 immunoreactivity was maintained in projections to the lesioned region, and enhanced in areas adjacent to those deafferented by the lesions. Expression of SNAP 25 mRNA was increased in denervated regions, and in neurons which would be expected to participate in the sprouting response. Tubulin-alpha 1 is an mRNA which is expressed at high levels in the fetal brain during periods of neurite outgrowth, but at low levels in the adult brain. The expression of T alpha 1 mRNA was increased in the rat hippocampal neurons following entorhinal lesions, and in the human hippocampus in patients with Alzheimer's disease. These results demonstrate that sprouting in the CNS may result in the replay of developmental patterns of gene expression. Examination of SNAP-25 and T alpha 1 mRNA expression and of SNAP-25 immunoreactivity may be useful in investigating alterations in major hippocampal circuits in a variety of conditions such as learning, hypoxia, hypoglycemia, and also in neurological disorders such as temporal lobe epilepsy and Alzheimer's disease.

Lesions of hippocampal circuitry define synaptosomal-associated protein-25 (SNAP-25) as a novel presynaptic marker

Synaptosomal-associated protein, 25 kD, (SNAP-25) is a novel protein containing a possible transition metal binding site and encoded by a neuronal-specific mRNA. We examined the distribution of SNAP-25 mRNA and protein in the hippocampal formation of the adult rat following kainic acid, colchicine, and entorhinal lesions. The results show that destruction of granule cells of the dentate gyrus and CA3 pyramidal cells did not diminish SNAP-25 immunoreactivity in the dendritic fields of these cells. In contrast, lesioned neurons exhibited an extensive loss of immunoreactivity at the site of their axonal projections. These results support the identification of SNAP-25 as a novel presynaptic protein. In addition, SNAP-25 immunoreactivity was increased in afferent fibers which project to areas adjacent to the deafferented region, and expression of SNAP-25 mRNA was increased in neurons deafferented by the lesion. Examination of SNAP-25 immunoreactivity and mRNA expression may provide a useful marker of major hippocampal pathways and of axonal plasticity in neurological disorders such as Alzheimer's disease and temporal lobe epilepsy.

The identification of a novel synaptosomal-associated protein, SNAP-25, differentially expressed by neuronal subpopulations

cDNA clones of a neuronal-specific mRNA encoding a novel 25-kD synaptosomal protein, SNAP-25, that is widely, but differentially expressed by diverse neuronal subpopulations of the mammalian nervous system have been isolated and characterized. The sequence of the SNAP-25 cDNA revealed a single open reading frame that encodes a primary translation product of 206 amino acids. Antisera elicited against a 12-amino acid peptide, corresponding to the carboxy-terminal residues of the predicted polypeptide sequence, recognized a single 25-kD protein that is associated with synaptosomal fractions of hippocampal preparations. The SNAP-25 polypeptide remains associated with synaptosomal membrane components after hypoosmotic lysis and is released by nonionic detergent but not high salt extraction. Although the SNAP-25 polypeptide lacks a hydrophobic stretch of residues compatible with a transmembrane region, the amino terminus may form an amphiphilic helix that may facilitate alignment with membranes. The predicted amino acid sequence also includes a cluster of four closely spaced cysteine residues, similar to the metal binding domains of some metalloproteins, suggesting that the SNAP-25 polypeptide may have the potential to coordinately bind metal ions. Consistent with the protein fractionation, light and electron microscopic immunocytochemistry indicated that SNAP-25 is located within the presynaptic terminals of hippocampal mossy fibers and the inner molecular layer of the dentate gyrus. The mRNA was found to be enriched within neurons of the neocortex, hippocampus, piriform cortex, anterior thalamic nuclei, pontine nuclei, and granule cells of the cerebellum. The distribution of the SNAP-25 mRNA and the association of the protein with presynaptic elements suggest that SNAP-25 may play an important role in the synaptic function of specific neuronal systems.

Truncated gag products encoded by Gv-1-responsive endogenous retrovirus loci

The conversion of endogenous or exogenous murine retroviruses to a leukemogenic phenotype involves recombination with retroviral sequences present in host genomic DNA. In the 129 Gix+ inbred strain, these endogenous sequences are replication defective but still express retroviral proteins under the apparent transcriptional control of the Gv-1 regulatory locus. To study the protein-coding potential of Gv-1-regulated endogenous retroviral loci, we used oligonucleotide probes directed to env deletion breakpoints identified in previously characterized cDNA clones. Four endogenous retroviral loci were isolated from a library of 129 Gix+ genomic DNA with these probes. Three loci cloned with the env deletion probe del env-1 had virtually identical proviral inserts by restriction analysis. A unique locus was identified and cloned with the del env-2 probe, which must therefore represent a Gv-1-responsive element. Restriction enzyme and nucleotide sequence analyses indicated that the del env-1 and del env-2 loci represented members of the polytropic and modified polytropic classes of endogenous retrovirus, respectively. Despite this divergence, members of both classes contained identical deletions of 19 nucleotides within p30gag and of 1,474 nucleotides from p10gag into the reverse transcriptase-coding region of pol, suggesting that a recombination event had occurred between these proviral sequences prior to insertion within the genome. The del env-1 and del env-2 loci retained coding capacity for truncated gag polyproteins, confirmed by in vitro translation and immunoprecipitation of the protein products. Nucleotide sequence comparison of the untranslated leader (L) regions of the del env-1 and del env-2 loci to a replication-competent ecotropic virus indicated regions that might be important to dispersion of these endogenous retroviral elements throughout the host genome.

A comparison of the clinical variations of the iridocorneal endothelial syndrome

Iridocorneal endothelial syndrome is generally considered to have three major variations: Chandler's syndrome, progressive (essential) iris atrophy, and the Cogan-Reese syndrome. To better understand the clinical significance of this classification, we studied the medical records of 37 consecutive patients from our practice, comparing the presentation and course of the three subgroups. Chandler's syndrome was the most common clinical variant within this spectrum of disease (21 cases). Patients with Chandler's syndrome had more severe corneal edema than the rest of the group, while those with progressive iris atrophy (8 cases) or the Cogan-Reese syndrome (8 cases) had worse secondary glaucoma.

Cellular localization of 1B236/myelin-associated glycoprotein mRNA during rat brain development

The protein encoded by the rat brain cDNA 1B236 has been shown to be identical to myelin-associated glycoprotein (MAG). In this report we describe the cellular distribution of 1B236/MAG mRNA transcripts in rat brain by using in situ hybridization. At postnatal day 20, large numbers of 1B236/MAG mRNA-containing oligodendrocytes are concentrated in myelinated fiber tracts and throughout gray matter regions. The presence of high levels of 1B236/MAG mRNA within oligodendrocytes at postnatal day 20 is consistent with the proposed role of MAG in formation of the myelin sheath during development. In the adult brain, our results suggest that not only is 1B236/MAG mRNA expressed at reduced levels within oligodendrocytes but also 1B236/MAG or a 1B236/MAG-like mRNA is present within neurons. This localization is consistent with the results of previous immunocytochemical studies using antibodies against the 1B236/MAG mRNA with different cell-type-specific patterns of expression suggests that oligodendrocytes and neurons employ different mechanisms for regulating the same gene. Thus, different cell types may use a similar cell adhesion molecule both during myelinogenesis and in the mature nervous system.

The behavioral effects of pesticides in male mice

Male Swiss mice, 25-30 g, were utilized to define some of the behavioral effects of the herbicides Lasso [alachlor 43%; (A)], Basalin [fluchloralin 45%; (F)], Premerge 3 [dinoseb 51%; (D)], and the fungicide Maneb-80 [maneb 80%; (M)]. These compounds were tested for their effects on locomotor activity and for their ability to establish a conditioned taste aversion following oral or dermal exposure. Individual and grouped (N = 5) activity measures were assessed immediately following the dermal administration of the commercially available pesticide formulations. Grouped activity measures were also assessed following the oral administration of the compounds. Total activity was significantly (p less than 0.05) increased over vehicle controls in both grouped and individual subjects by A, F, and D following dermal administration. Grouped activity measures were also increased by A, F, D, and M following the oral administration of the compounds. Similar subjects were tested in a conditioned taste aversion paradigm using a normally preferred 0.3% saccharin solution. Animals were given 30 min access to the saccharin solution followed immediately by the administration of the pesticide or control solution. Twenty-four hours later, animals were given the choice of 2 solutions, one containing water and the other the 0.3% saccharin solution. The percent saccharin consumed and the total fluid intake were calculated for each group (N = 8/group). A, F, and D produced a significant aversion to (N = 8/group) the saccharin following both oral and dermal administration. Oral administration of M, but not dermal exposure, also resulted in a flavor aversion. Total fluid intake, however, was not altered by any of the treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurotransmitter abnormalities in Borna disease

Borna disease (BD) agent is an infectious pathogen that causes progressive central nervous system (CNS) dysfunction in a wide range of vertebrate hosts. The course of BD in adult rats is biphasic. The acute phase is characterized by aggressive behavior and inflammatory cell infiltrates in brain. With chronic infection animals become listless and inflammation resolves. BD antigens are similarly distributed in neurons in hippocampus, neocortex, cerebellum and brainstem in acutely and chronically infected animals. We have recently examined brain levels of neuronal transcripts in rats with acute and chronic BD. Levels for 3 of these mRNAs, cholecystokinin, glutamic acid decarboxylase and somatostatin, were decreased in acutely infected rats and increased toward control values in chronically infected rats. A fourth transcript, MuBr8, correlated in distribution with BD antigen, was persistently decreased throughout the course of infection. These data may have implications for understanding the pathogenesis of neurologic disturbances in BD and other inflammatory CNS diseases.

Massive axillary lymph-node hyperplasia in pregnancy: a case report

We present a case of massive benign axillary lymph-node hyperplasia in pregnancy and the puerperium in the absence of any breast or axillary pathology, posing a difficult management dilemma.

Fatal disseminated intravascular coagulation secondary to streptococcal cervicitis

A case of beta haemolytic Group A streptococcal cervicitis causing disseminated intravascular coagulation, bacteraemic shock, and death in a 57 year old woman is presented.

Behavioral effects of pydrin and ambush in male mice

Male Swiss mice, 20-25 g, were utilized to assess the effects of dermal and oral administration of the pyrethroid insecticide formulations Pydrin (30% fenvalerate) and Ambush (25.6% permethrin). Animals were subjected to a conditioned taste aversion procedure using a normally preferred 0.3% saccharin solution. Subjects were allowed 30 min access to a drinking syringe containing the saccharin solution, followed immediately by the administration of the pyrethroid or control solution. Pydrin (0.3, 3.0, or 30 mg/kg orally; 60, 600, or 1800 mg/kg dermally) and Ambush (0.5, 5.0, or 50 mg/kg orally; 30, or 300 mg/kg dermally) produced significant (p less than 0.05) reductions in the percent saccharin consumed. Total fluid intake, however, was not significantly altered by any of the treatments. The effect of the insecticides on both grouped and individual activity was also assessed in 20-25 g male Swiss mice. Activity measurements were taken over the 4-hr time period immediately following the administration of the pyrethroid or control solution. Pydrin (30 mg/kg orally; 600 and 1800 mg/kg dermally) and Ambush (50 mg/kg orally; 300 mg/kg dermally) significantly (p less than 0.05) increased activity in both grouped and individually tested mice. When subjects were individually tested, significant increases were seen in non-ambulatory, but not in ambulatory activity. The results of this work indicate that administration of the commercially available preparations of Pydrin and Ambush in mice at doses that do not induce the tremor and choreoathetosis-salivation syndromes usually associated with pyrethroid insecticides may result in behavioral changes.

Distribution of precursor amyloid-beta-protein messenger RNA in human cerebral cortex: relationship to neurofibrillary tangles and neuritic plaques

Neurofibrillary tangles (NFT) and neuritic plaques (NP), two neuropathological markers of Alzheimer disease, may both contain peptide fragments derived from the human amyloid beta protein. However, the nature of the relationship between NFT and NP and the source of the amyloid beta proteins found in each have remained unclear. We used in situ hybridization techniques to map the anatomical distribution of precursor amyloid-beta-protein mRNA in the neocortex of brains from three subjects with no known neurologic disease and from five patients with Alzheimer disease. In brains from control subjects, positively hybridizing neurons were present in cortical regions and layers that contain a high density of neuropathological markers in Alzheimer disease, as well as in those loci that contain NP but few NFT. Quantitative analyses of in situ hybridization patterns within layers III and V of the superior frontal cortex revealed that the presence of high numbers of NFT in Alzheimer-diseased brains was associated with a decrease in the number of positively hybridizing neurons compared to controls and Alzheimer-diseased brains with few NFT. In contrast, no correlation was found between the densities of NP and neurons containing precursor amyloid-beta-protein mRNA transcripts. These findings suggest that the expression of precursor amyloid-beta-protein mRNA may be a necessary but is clearly not a sufficient prerequisite for NFT formation. In addition, these results may indicate that the amyloid beta protein, present in NP in a given region or layer of cortex, is not derived from the resident neuronal cell bodies that express the mRNA for the precursor protein.

Differential regulation of amyloid-beta-protein mRNA expression within hippocampal neuronal subpopulations in Alzheimer disease

We have mapped the neuroanatomical distribution of amyloid-beta-protein mRNA within neuronal subpopulations of the hippocampal formation in the cynomolgus monkey (Macaca fascicularis), normal aged human, and patients with Alzheimer disease. Amyloid-beta-protein mRNA appears to be expressed in all hippocampal neurons, but at different levels of abundance. In the central nervous system of monkey and normal aged human, image analysis shows that neurons of the dentate gyrus and cornu Ammonis fields contain a 2.5-times-greater hybridization signal than is present in neurons of the subiculum and entorhinal cortex. In contrast, in the Alzheimer disease hippocampal formation, the levels of amyloid-beta-protein mRNA in the cornu Ammonis field 3 and parasubiculum are equivalent. These findings suggest that within certain neuronal subpopulations cell type-specific regulation of amyloid-beta-protein gene expression may be altered in Alzheimer disease.

Mapping X-linked ophthalmic diseases. III. Provisional assignment of the locus for blue cone monochromacy to Xq28

Blue cone monochromacy (BCM) is an infrequent X-linked retinal disorder typified by poor central visual acuity and color discrimination, early onset of nystagmus, variable degrees of myopia and astigmatism, and a nearly normal retinal appearance. The physiologic functions of rods and blue cones are preserved. The regional location of the genetic mutation causing BCM has been unknown. We have applied the modern molecular techniques of analysis of restriction fragment length polymorphisms to three multigenerational kindreds in which BCM is segregating. Significant linkage is established to two DNA markers, DXS15 and DXS52, each of which maps to the vicinity of Xq28. Regional localization of the locus for BCM has the potential to improve carrier detection and to provide antenatal diagnosis in families at risk for the disease.

The effects of d-amphetamine on food competition in male rats

Male Wistar rats were tested in 3 competitive situations to determine the effects of d-amphetamine (AMP) on competitive behavior. Subjects were initially tested in a fixed-pair food competition paradigm. Based on the percentage of pellets obtained, a winner and loser were defined for each pair. AMP (2.0 and 4.0 mg/kg) was then administered to one or both members of pair, and the effects of the drug on the defined winners and losers were determined. AMP did not significantly alter the percentage of pellets obtained by losers except when only the winners were administered AMP (4.0 mg/kg). Subjects were then tested in a round-robin competition paradigm in which each subject was paired with every other subject. The animals were ranked according to the percentage of pellets obtained out of a possible 450 pellets. AMP (2.0 mg/kg) decreased pellet acquisition in higher ranking subjects, whereas pellet acquisition was increased in lower ranking subjects. The effects of AMP were also evaluated in a "worker-parasite" paradigm. Subjects were individually conditioned to press a lever using an FI schedule for presentation of a food pellet. When the lever was located on the wall opposite the food hopper, a worker and parasite were defined for each pair. The worker was the subject that made the most responses on the lever while obtaining fewer reinforcements. Subjects that were defined as winners in the fixed pair food competition emerged as the workers in this situation. AMP (0.8 mg/kg) given concurrently to both subjects resulted in a reversal of roles; the parasites now emitted the majority of responses and obtained less pellets. The data indicate that AMP has a differential effect on participants in competitive situations when all subjects in the situation are treated.

Localization of amyloid beta protein messenger RNA in brains from patients with Alzheimer's disease

The distribution of cells containing messenger RNA that encodes amyloid beta protein was determined in hippocampi and in various cortical regions from cynomolgus monkeys, normal humans, and patients with Alzheimer's disease by in situ hybridization. Both 35S-labeled RNA antisense and sense probes to amyloid beta protein messenger RNA were used to ensure specific hybridization. Messenger RNA for amyloid beta protein was expressed in a subset of neurons in the prefrontal cortex from monkeys, normal humans, and patients with Alzheimer's disease. This messenger RNA was also present in the neurons of all the hippocampal fields from monkeys, normal humans and, although to a lesser extent in cornu ammonis 1, patients with Alzheimer's disease. The distribution of amyloid beta protein messenger RNA was similar to that of the neurofibrillary tangles of Alzheimer's disease in some regions, but the messenger RNA was also expressed in other neurons that are not usually involved in the pathology of Alzheimer's disease.

Phacofragmentation and aspiration for cataract extraction in dogs: 56 cases (1980-1984)

Fifty-six cases of cataract removal in dogs by phacofragmentation and aspiration were reviewed. Improvement of vision was detected in the immediate postoperative period in 53 (94.6%) of 56 dogs. Vision was present in 25 (85.2%) of 29 dogs evaluated at 2 years after surgery, and in 5 (71.4%) of 7 dogs evaluated 4 years after surgery. Reasons for failure of visual improvement and complications in visual eyes were related primarily to development of postoperative anterior uveitis. Age of the dog at surgery was not a significant factor in the restoration of vision.

The 3' long terminal repeat of a transcribed yet defective endogenous retroviral sequence is a competent promoter of transcription

Although actively transcribed and present as multiple genomic copies, a distinct class of endogenous murine leukemia virus-related sequence does not give rise to infectious virus. Since the long terminal repeat at the 3' terminus provides the transcriptional start site after reintegration, we determined the structure and potential promoter activity of that sequence obtained from cDNA of endogenous retroviral transcripts. These studies demonstrate that the distinctive 3' long terminal repeat sequence of these transcripts could serve as an effective promoter of transcription and, therefore, may not be the primary defect in the infectious cycle of retroviral replication but may result in the propagation of these endogenous retroviral sequences in the genome as retrotransposons.

Aerobic and anaerobic swimming speeds of spermatozoa investigated by twin beam laser velocimetry

The motility of bovine and ovine spermatozoa has been studied under aerobic and anaerobic conditions, using a dual beam laser velocimeter. Cells swimming under aerobic conditions were found to be characterized by a translational swimming speed and a rotation rate that were approximately double those of cells swimming in an anaerobic environment. Both types of spermatozoa have been found to exhibit a sudden coordinated transition between fast and slow swimming states when the available oxygen is exhausted. This transition from aerobic to anaerobic swimming states has also been shown to be reversible. Studies of the duration of aerobic motility using the same apparatus have shown that the cells have a constant motile efficiency over the temperature range 32 degrees-42 degrees C.

The behavioral and toxicological effects of testosterone pellet implantation

Forty gonadally intact male Wistar rats, 200-225 g, were utilized to study the behavioral and physiological effects of testosterone (T) pellet administration. T was administered via pellets (10, 25, 50, and 100 mg) implanted subcutaneously in the dorsal region of the neck. Fifty mg lactate pellets were utilized as the control. T plasma levels were determined using RIA procedures on days 30, 60, and 90 after pellet implantation. T (50 and 100 mg) resulted in plasma concentrations significantly greater than controls. T (100 mg) and lactate control groups were subjected to a competition situation utilizing an estrogen-primed female as the goal object. Subjects were exposed to the test procedure prior to the implantation of the pellets. T resulted in previously defined losers becoming winners in the competition situation on days 30, 60, and 90 post-implantation. T implantation did not significantly affect muricidal behavior as compared to lactate controls. On day 90, the subjects were sacrificed, and the organ/body-weight ratios determined for the heart, liver, testes, and skeletal muscles of the left shoulder girdle. T (100 mg) resulted in a decrease in the testes/body-weight ratio as compared to controls, while the liver/body-weight ratio was increased in this group T (100 mg) also resulted in an increase in the activity of serum enzyme glutamic-oxaloacetic transaminase (SGOT) on day 90 post-implantation. Food intake and body weight were monitored throughout the course of the study. However, no significant differences from controls were noted.

The inflammatory reaction in the airways in an animal model of the late asthmatic response

The late asthmatic response is defined as airway obstruction that occurs hours after antigen exposure in some atopic asthmatics. The importance of this reaction is that the airway obstruction may be severe, prolonged, and difficult to control unless corticosteroids are employed. In addition, this response may lead to an increase in airway reactivity. To investigate the immunopathogenesis of this disorder, an animal model in rabbits was developed. In this model, antigen-specific IgE was associated with the late asthmatic response and antigen-specific IgG was associated with blunting of the reaction. Antigen challenge of immune rabbits led to edema within the large airways shortly after antigen exposure, with infiltration of inflammatory cells (neutrophils and eosinophils) into the large and small airways during the late response. The infiltrates became more mononuclear with time and resolved over 10 days. As in humans, the late response was associated with an increase in airway reactivity and correlated temporally with infiltration of the airways with neutrophils and eosinophils. The contribution of granulocytic cells to the airway responses to antigen was studied by granulocyte depletion, which prevented both the late response and the heightened airway reactivity. In addition, transfusion of a neutrophil-rich population of white cells into granulocytopenic immune rabbits restored both responses. Thus, in this animal model, the antigen-induced late asthmatic response and subsequent increase in airway reactivity were dependent on the presence of granulocytes at the time of exposure to antigen.