Classical conditioning modifies cytochrome oxidase activity in the auditory system

The effects of excitatory classical conditioning on cytochrome oxidase activity in the central auditory system were investigated using quantitative histochemistry. Rats in the conditioned group were trained with consistent pairings of a compound conditional stimulus (a tone and a light) with a mild footshock, to elicit conditioned suppression of drinking. Rats in the pseudorandom group were exposed to pseudorandom presentations of the same tone, light and shock stimuli without consistent pairings. Untrained rats in a naive group did not receive presentations of the experimental stimuli. The findings demonstrated that auditory fear conditioning modifies the metabolic neuronal responses of the auditory system, supporting the hypothesis that sensory neurons are responsive to behavioural stimulus properties acquired by learning. There was a clear distinction between thalamocortical and lower divisions of the auditory system based on the differences in metabolic activity evoked by classical conditioning, which lead to an overt learned behavioural response versus pseudorandom stimulus presentations, which lead to behavioural habituation. Increases in cytochrome oxidase activity indicated that tone processing is enhanced during associative conditioning at upper auditory structures (medial geniculate nucleus and secondary auditory cortices). In contrast, metabolic activation of lower auditory structures (cochlear nuclei and inferior colliculus) in response to the pseudorandom presentation of the experimental stimuli suggest that these areas may be activated during habituation to tone stimuli. Together these findings show that mapping the metabolic activity of cytochrome oxidase with quantitative histochemistry can be successfully used to map regional long-lasting effects of learning on brain systems.

The effect of auditory feedback on the control of oral-nasal balance by pediatric cochlear implant users

OBJECTIVE

This study examined the control of oral-nasal balance by pediatric cochlear implant (CI) users, with and without auditory feedback.

DESIGN

Five CI users read lists of sentences in two conditions: with their devices on and with their devices off. Their oral-nasal balance (ratio of energy radiated from the oral and nasal cavities) was measured in both conditions and compared with values obtained from children with normal hearing.

RESULTS

CI users showed different patterns of abnormal oral-nasal balance with their devices off, but they generally achieved values that were closer to normal when their devices were on.

CONCLUSIONS

The results suggest that children with CIs use the auditory signal provided by their device to improve their control of nasalization. It is also possible that at least part of the changes in oral-nasal balance were driven by changes in related articulatory parameters.

Transcription of the juvenile hormone esterase gene under the control of both an initiator and AT-rich motif

The binding of transcription factors to the core promoter of the juvenile hormone esterase gene was functionally characterized using both a cell-free in vitro transcription functional assay and a cell transfection assay. A core JHE promoter (-61 to +28 bp relative to transcription start site) supported faithful transcription from the in vivo transcription start site. The nuclear extracts from the Sf9 insect cell line that provided transcription from that template also bound to that template as a probe in gel-mobility shift assays. Deletion or transversion of the initiator-binding motif (-1 to +4 bp) abolished detectable transcription either in vitro or in transfected cells. An AT-rich motif (ATATAT; -28 to -23 bp) serves another transcription factor-binding site. Mutation of the AT-rich motif to a canonical TATA-box preserved transcription, while either its deletion or complete transversion abolished or significantly reduced detectable transcriptional activity. These results indicate that, under these conditions, the functional operation of this core promoter approaches that of a composite promoter in which both the TATA- and initiator-binding protein complexes are necessary, even for basal transcription. On the other hand, these debilitating mutations to either the TATA box or initiator motif did not prevent the ability of the corresponding gel-shift competitive probes to compete with the wild-type promoter for binding by the transcription factors. Even a double transversion of both the AT-rich motif and the initiator-binding motif was able to competitively displace the protein complex that bound to the labelled wild-type probe. These data strongly indicate the presence of (an) additional core-promoter-associated transcription factor(s) (that is not the 'downstream element') that contact(s) the AT-binding complex and/or initiator-binding factor with sufficient avidity to remove them from binding to the competing wild-type promoter sequence.

Preultimate 4th/5th instar Trichoplusia ni naturally-injected with venom/calyx fluid from Chelonus curvimaculatus precociously metamorphose, rather than obey the metamorphic size threshold that would normally compel molting to a 5th/6th instar

In normally regulated larval metamorphosis of Trichoplusia ni, a 4th, 5th or other numbered instar is a 'preultimate' instar, and will normally continue larval molting, if the larva has not yet surpassed the critical (minimal) size threshold corresponding to attainment of the 'ultimate' (metamorphic) instar. Natural injection of T. ni embryos with venom/calyx fluid of female Chelonus sp. near curvimaculatus caused 'penultimate' 4th or 5th instar larvae that would normally molt at least once more, to a 5th/6th instar, to instead precociously metamorphose without another larval molt. These effects were observed in naturally-injected insects that never contained either a parasite larva, a viable parasite embryo, or a parasite egg. These data demonstrate that this effect of venom/calyx fluid of this wasp to induce precocious metamorphosis, at an instar earlier than would otherwise have typically occurred under normal growth conditions, does not require the presence of a parasite larva. Other data did indicate the parasite larva contributes an additional effect that causes a 4th instar host (that from its size would normally require not just one, but at least two more larval molts to reach the metamorphic instar) to not grow to the size metamorphic threshold, but to instead, precociously metamorphose at an even smaller size than occurs with the venom/calyx fluid alone. Additionally, arylphorin was precociously highly expressed in parasitized hosts in a manner independent of a decline in the host JH titer. Therefore, the main target of the venom/calyx fluid activity to induce precocious metamorphosis appears to be an event upstream of the decline in JH production by the corpora allata. Pseudoparasitized hosts become developmentally arrested as precocious prepupae and express a 2.7kb polydnavirus transcript. The larger (but still subthreshold size) larvae showed less suppressed prepupal ecdysteroid titers, less developmental suppression, and a much weaker expression of that transcript. A general model for mechanisms of action of chelonine venom/calyx fluid, and larvae, to cause precocious host metamorphosis and suppressed prepupal development is presented that is based on the current 'size threshold' model of normal lepidopteran development, rather than the older, displaced 'instar count' model. By basing the model for chelonine regulation of host development on the current 'size threshold' model for normal development, the proposed model for chelonine action both accounts for observations reported on various species of that subfamily and makes useful, testable predictions.

Association and clonal distribution of trisomy 12 and 13q14 deletions in chronic lymphocytic leukaemia

The coexistence of trisomy 12 and deletions of chromosome 13 (13q12-q32) has rarely been observed in chronic lymphocytic leukaemia (CLL). Fluorescence in situ hybridization (FISH) performed on 600 consecutive CLL patients revealed the association of trisomy 12 and 13q14 deletion, of at least one of the three markers analysed (RB1, D13S319 and D13S25), in 55 cases (9% of 600 and 46% of 120 trisomy 12 cases). Trisomy 12 and isolated RB1 deletion were seen in 14/120 cases, trisomy 12 and D13S319/D13S25 deletion with diploid RB1 in 19/118, and trisomy 12 and deletion encompassing the three 13q markers studied in 22/118 cases. The heterogenous distribution of trisomy 12 and 13q deletions within the neoplastic B cells suggests that they are secondary rather than primary events in CLL leukaemogenesis.

Differentiation and reversal of malignant changes in colon cancer through PPARgamma

PPARgamma is a nuclear receptor that has a dominant regulatory role in differentiation of cells of the adipose lineage, and has recently been shown to be expressed in the colon. We show here that PPARgamma is expressed at high levels in both well- and poorly-differentiated adenocarcinomas, in normal colonic mucosa and in human colon cancer cell lines. Ligand activation of this receptor in colon cancer cells causes a considerable reduction in linear and clonogenic growth, increased expression of carcinoembryonic antigen and the reversal of many gene expression events specifically associated with colon cancer. Transplantable tumors derived from human colon cancer cells show a significant reduction of growth when mice are treated with troglitazone, a PPARgamma ligand. These results indicate that the growth and differentiation of colon cancer cells can be modulated through PPARgamma.

The neglected saliva: medically important toxins in the saliva of human lice

Although there has been a great deal of research effort within the last two decades on identifying the active components of the saliva of blood-sucking ticks, mosquitoes, biting flies, fleas and bugs, essentially neglected have been the human lice. Despite initial reports in the early part of this century suggestive of vasodilatory, anticoagulant and immunosuppressive properties of the saliva, for the next 50 years there were no biochemical studies on the active principles. Very recently, anatomical and biochemical studies have begun to characterize the bioactive molecules in lice saliva. The louse stocks a salivary vasodilator in excess over what is needed for a single bite, and injects similar amounts at each successive bite. The vasodilator in lice saliva appears to have different pharmacological properties than peroxidative, oxidative and maxidilan types of vasodilators reported from other blood-sucking insects. Possible anticoagulant activities have also been characterized. This belated, but welcome, interest comes at a time of resurgence of lice-born disease in certain parts of Africa, and of resistance to chemical control in Europe and North America.

Impaired B-lymphopoiesis, myelopoiesis, and derailed cerebellar neuron migration in CXCR4- and SDF-1-deficient mice

The chemokine stromal cell-derived factor 1, SDF-1, is an important regulator of leukocyte and hematopoietic precursor migration and pre-B cell proliferation. The receptor for SDF-1, CXCR4, also functions as a coreceptor for T-tropic HIV-1 entry. We find that mice deficient for CXCR4 die perinatally and display profound defects in the hematopoietic and nervous systems. CXCR4-deficient mice have severely reduced B-lymphopoiesis, reduced myelopoiesis in fetal liver, and a virtual absence of myelopoiesis in bone marrow. However, T-lymphopoiesis is unaffected. Furthermore, the cerebellum develops abnormally with an irregular external granule cell layer, ectopically located Purkinje cells, and numerous chromophilic cell clumps of abnormally migrated granule cells within the cerebellar anlage. Identical defects are observed in mice lacking SDF-1, suggesting a monogamous relationship between CXCR4 and SDF-1. This receptor-ligand selectivity is unusual among chemokines and their receptors, as is the function in migration of nonhematopoietic cells.

Differential regulation of the interleukin-12 receptor during the innate immune response to Leishmania major

Previous studies have shown the central role of interleukin 12 (IL-12) in the development of resistance to Leishmania major infection in C3H mice. We now show that during the innate immune response the lymph node cells of L. major-infected C3H mice upregulate the IL-12 receptor on CD4(+), CD8(+), and B220(+) cells. An increase in the ability of the lymph node cells to bind IL-12 correlates with 9.3- and 4.6-fold increases in the mRNA expression levels of the IL-12Rbeta1 and -beta2 subunits, respectively. In contrast, BALB/c mice, which are susceptible to L. major infection, have no increase in the ability of the lymph node cells to bind IL-12 and correspondingly smaller increases in the mRNA expression levels of the IL-12Rbeta1 and -beta2 subunits of 2- and 1.5-fold, respectively. Neutralizing IL-4 and the administration of exogenous IL-12 upregulate IL-12R expression in BALB/c mice, while the neutralization of IL-12 in C3H mice blocks increased IL-12 receptor expression. These experiments reveal an important role for the regulation of the IL-12 receptor during the innate immune response after infection of mice with a pathogen.

Structure and function of proteins controlling strain-specific pathogen resistance in plants

Recently recognised structural and amino acid sequence similarities between plant disease resistance (R) proteins and animal proteins such as Apaf-1 and CED-4 are providing conceptual models for resistance protein function. Data from extensive DNA sequencing of resistance gene families are indicating that the leucine-rich repeat motif is an important determinant of gene-for-gene specificity and that intergenic DNA sequence exchange is a major contributor to R gene diversity.

Characteristic proliferations of reticular and dendritic cells in angioimmunoblastic lymphoma

Angioimmunoblastic lymphoma (AIL) is a T-cell proliferation with a distinct clinical presentation that often poses a difficult diagnostic challenge. Angioimmunoblastic lymphoma is characterized by prominent vascular and stromal proliferations. Using a panel of antibodies, we investigated the nature of the stromal component in 15 cases of AIL as compared with 40 cases of nodal-based peripheral T-cell lymphoma (PTCL) of other types. As has been previously noted, extrafollicular proliferations of follicular dendritic cells (detected by CD21 and low molecular-weight nerve growth factor receptor staining) were highly associated with AIL and were only rarely seen in other lesions. Unexpectedly, large networks of desmin-positive reticulum cells also were noted in all cases of AIL evaluated. These cells with characteristic long cytoplasmic processes were present in much smaller numbers or only rarely in other types of peripheral T-cell lymphoma. This population of nodal stromal cells, a subset of the fibroblastic reticulum cells detected by vimentin immunostaining, may be responsible for the prominent reticulum deposition seen in AIL. No association of AIL with proliferations of other types of reticulum cells (e.g., interdigitating dendritic cells or histiocytes) was noted. These findings suggest that networks of follicular dendritic and desmin-positive reticulum cells are useful diagnostic features in angioimmunoblastic lymphoma and probably are related to the pathogenesis of this entity.

Vancouver's "vision of hell" requires special type of MD

Vancouver's Downtown Eastside, the city's skid row, is in a state of emergency. Some 7000 injection drug users, about 40% of whom are HIV positive, mingle with prostitutes and the city's street people. The doctors who care for them say it is a potent and dangerous mix.

Perturbation of TSG101 protein affects cell cycle progression

tsg101 was recently identified as a tumor susceptibility gene by functional inactivation of allelic loci in mouse 3T3 fibroblasts. Although previous studies suggested that homozygous intragenic deletion of TSG101 is rare in breast cancer cells and specimens, the neoplastic phenotype caused by tsg101 inactivation implicated that tsg101 may play a significant role in cell growth control. Here, we characterize mouse polyclonal and monoclonal antibodies that specifically recognize the TSG101 protein (molecular mass, 46 kDa) in whole-cell lysates by straight Western blot analysis. By indirect immunofluorescence staining, TSG101 was found to be localized in the cytoplasm throughout the entire cell cycle. However, the nuclear staining increases from G1 to S phase and becomes dominant in late S phase. TSG101 is mainly distributed surrounding the chromosomes during M phase. The expression level of TSG101 is not cell cycle dependent. It is possible that the relocalization of TSG101 from the cytoplasm into the nucleus may be relevant to its function. Microinjection of both polyclonal and monoclonal antibodies specific to TSG101 into cells during G1 or S phase results in cell cycle arrest. Furthermore, overexpression of TSG101 leads to cell death, suggesting that the appropriate amount of TSG101 is critical for cell cycle progression. Taken together, these results suggest that neoplastic transformation caused by TSG101 deficiency may result from bypassing of the cell cycle checkpoints.

Quantification of alterations in structure and function of elastin in the arterial media

The structure of medial elastin determines arterial function and affects wall mechanical properties. The aim of this study was to (1) characterize the structure of elastin in terms of textural features, (2) relate structural parameters to total number of cardiac cycles (TC), and (3) determine the contribution of medial elastin to lumen mechanical stress. Images of pressure-fixed aortic sections stained for elastin were obtained from specimens collected postmortem from 35 animals of different species with a wide range of age, heart rate, and TC and divided into 2 groups: TClow=3.69+/-0.38x10(8) (n=17) and TChigh=15.8+/-2.38x10(8) (n=18) (P<0.001). A directional fractal curve was generated for each image, and image texture was characterized by directional fractal curve parameters. Elastin volume fraction and interlamellar distance were obtained by image analysis. Wall stress distribution was determined from a finite element model of the arterial wall with multiple layers simulating elastin lamellae. DFC amplitude was related to elastin volume fraction. Increased TC (TClow versus TChigh) was associated with lower directional fractal curve amplitude (0.23+/-0.02 versus 0.14+/-0.02; P<0.001), reduced elastin volume fraction (36.5+2.6% versus 25.7+2.1%; P<0.01), and increased interlamellar distance (8.5+/-0.5 versus 11.5+/-1.0 microm; P<0.05). Loss of medial elastic function increased pressure-dependent maximal circumferential stress. Structural alterations of medial elastin, quantified by fractal parameters, are associated with cumulative effects of repeated pulsations due to the combined contribution of age and heart rate. Loss of medial functional elasticity increases luminal wall stress, increasing the possibility of endothelial damage and predisposition to atherosclerosis.

Median nerve compression in Proteus syndrome

Proteus syndrome is a multi-organ disorder, a prime feature of which is localized gigantism, usually clinically obvious. Symptoms secondary to hypertrophy of nerves has not been previously recognized as a part of the syndrome.

Ketorolac versus acetaminophen-codeine in the emergency department treatment of acute low back pain

Acute low back pain is a common problem in the emergency department (ED). Effective management of acute pain enhances early rehabilitation and recovery. Given the importance of inflammatory mediators in pain generation and the adverse effects associated with opioids, it is logical to expect that a non-opioid agent with antiinflammatory and analgesic properties would provide excellent analgesia with fewer adverse effects. This double-blind, randomized, multicenter clinical trial, performed in six university and community hospital EDs, compares the analgesic efficacy and adverse effects of ketorolac to those of acetaminophen-codeine in ED patients with acute musculoskeletal low back pain. Our hypothesis was that ketorolac would provide superior analgesia with fewer adverse effects. One hundred twenty-three patients with acute low back pain were randomized to receive ketorolac (KET, N = 63) or acetaminophen-codeine (ACOD, N = 60). Most (79%) were males, and the mean age was 34.5 years. After baseline clinical assessment, patients were treated with ketorolac (10 mg every 4 to 6 h as needed, up to four daily doses) or acetaminophen-codeine (600 mg-60 mg, respectively, every 4 to 6 h as needed, up to six daily doses) and followed for one week. Pain intensity was assessed on visual analogue and categorical scales. Functional capacity, overall pain relief, and overall medication rating were assessed on categorical scales. Adverse events were documented. Primary outcomes included: 1) Pain intensity differences, based on visual analogue scores, for the 0 to 6 h treatment phase. 2) Incidence of adverse events. Secondary outcomes included analgesic efficacy, functional capacity, and overall subjective drug evaluation at one week. Both drugs provided substantial pain relief, with maximal effect 2.2 h after oral dosing. There were no significant differences in analgesic efficacy, functional capacity, or overall pain relief between the two groups. Sixteen patients (10 KET vs. 6 ACOD, NS) withdrew prematurely because of drug inefficacy. Patients in the ACOD group reported significantly more adverse drug events and serious adverse drug events. Seven patients--all in the ACOD group--withdrew from the study because of adverse drug events. Based on comparable efficacy and a superior adverse event profile, ketorolac was preferable to acetaminophen with codeine for the treatment of acute low back pain in the ED.

Self-reported delinquent behavior and psychosocial functioning in inner-city teenagers: a brief report

Evaluated psychosocial characteristics of inner-city ninth graders exceeding a cutoff for clinically significant delinquent behaviors (n = 27), as compared to youth whose self-reported delinquent behaviors fell below this cutoff (n = 136). Youth reporting high levels of delinquent behavior reported more life stress, depression and anxiety, lower self-concept, and less cohesive families than other students. Females reporting high levels of delinquent behavior were more likely to have poor classroom and school attendance than other females; this relationship did not hold for males.

Antituberculosis drug-induced hepatotoxicity. The role of hepatitis C virus and the human immunodeficiency virus

Until recently it was thought that age greater than 35 yr was the main risk factor for the development of drug-induced hepatitis (DIH) in patients receiving antituberculosis therapy. We conducted a study to determine whether infection with either the hepatitis C virus or the human immunodeficiency virus (HIV) were significant risk factors for the development of DIH in patients receiving antituberculosis therapy. Our study consisted of two parts. In the first part, 134 consecutive patients admitted for the treatment of tuberculosis (TB) were followed for the development of DIH. All of these patients were also screened for the presence of hepatitis C and HIV. In the second part of the study, those patients who were hepatitis C positive and who developed DIH on repeated reintroduction of the anti-TB drugs were offered a liver biopsy. If active inflammation, which may be suggestive of hepatitis C infection, was present on the biopsy specimen, treatment with alpha-interferon was begun and the anti-TB drugs were subsequently reintroduced. During the 18 mo of the study, 22 patients developed DIH. The relative risk of developing DIH if the patient was hepatitis C or HIV positive was fivefold and fourfold, respectively (p < 0.05). If a patient was coinfected with both hepatitis C and HIV the relative risk of developing DIH was increased 14.4-fold (p < 0.002). In the treatment part, four patients were treated with alpha-interferon, and all were able to undergo the reintroduction of anti-TB therapy without reoccurrence of DIH. Infection with hepatitis C and HIV are independent and additive risk factors for the development of DIH during TB therapy. The treatment of hepatitis C with alpha-interferon may allow the reintroduction of anti-TB agents in those who previously developed DIH when exposed to these drugs.