Cerebellar brain-derived neurotrophic factor-TrkB defect associated with impairment of eyeblink conditioning in Stargazer mutant mice

In the spontaneous ataxic mutant mouse stargazer, there is a selective reduction of brain-derived neurotrophic factor (BDNF) mRNA expression in the cerebellum. BDNF protein levels in the cerebellum are reduced by 70%. Despite normal levels of full-length and truncated TrkB receptor, constitutive and neurotrophin-4/5-induced tyrosine phosphorylation was significantly reduced in several signal transduction molecules, including phospholipase-Cgamma1, erk1, and erk2. Morphological examination revealed an increased number of external granule cells at postnatal day 15 and the presence of abnormal neurons resembling immature granule cells in the adult. These abnormalities are associated with a severe impairment in the acquisition of classical eyeblink conditioning, indicating cerebellar malfunction. Our data suggest that normal BDNF expression and TrkB signal transduction in the cerebellum are necessary for learning and plasticity in this model.

Impaired eye-blink conditioning in waggler, a mutant mouse with cerebellar BDNF deficiency

In addition to their trophic functions, neurotrophins are also implicated in synaptic modulation and learning and memory. Although gene knockout techniques have been used widely in studying the roles of neurotrophins at molecular and cellular levels, behavioral studies using neurotrophin knockouts are limited by the early-onset lethality and various sensory deficits associated with the gene knockout mice. In the present study, we found that in a spontaneous mutant mouse, waggler, the expression of brain-derived neurotrophic factor (BDNF) was selectively absent in the cerebellar granule cells. The cytoarchitecture of the waggler cerebellum appeared to be normal at the light microscope level. The mutant mice exhibited no sensory deficits to auditory stimuli or heat-induced pain. However, they were massively impaired in classic eye-blink conditioning. These results suggest that BDNF may have a role in normal cerebellar neuronal function, which, in turn, is essential for classic eye-blink conditioning.

Intestinal IgA plasma cells of the B1 lineage are IL-5 dependent

Two lineages of B cells, designated B1 and B2 cells, have been identified based upon their origins, anatomical distribution, cell surface markers, antibody repertoire and self-replenishing potential. B1 cells are maintained by self-renewal of cells resident in the peritoneal cavity (PerC) and they utilize a limited repertoire of germline V-region genes, mostly directed against ubiquitous bacterial antigens such as phosphoryl choline (PC). B2 cells are replenished from bone marrow precursors and use a larger repertoire of immunoglobulin V-region genes. Whereas most immunoglobulin A (IgA) plasma cells in the intestine derive from B2 lineage precursors in the Peyer's patch, a subpopulation of Per C-derived B1 cells populate the intestinal lamina propria where they mature into IgA plasma cells. In previous in vivo studies we have shown that whereas IgA+ B2 cells are interleukin (IL)-6 dependent, B1 cells are IL-6 independent. In view of the in vitro evidence that IL-5 is also involved in IgA expression, in the studies reported here we have used IL-5-deficient mice to evaluate the role of IL-5 in vivo in IgA expression in the gut. The results demonstrate that although total IgA cell numbers are only marginally depressed in IL-5-deficient mice, there is a marked selective depletion of IgA+ cells of the B1 lineage in the gut and a corresponding depression in the capacity of these mice to mount an intestinal response to a B1 antigen (PC) but not to a B2 antigen (oralbumin; OVA), reflecting intact B2-derived IgA cell function but a defect in the B1 cell contribution to IgA responses in IL-5 deficient mice. Collectively these data demonstrate differential cytokine regulation of subsets of IgA+ cells in the gut in that IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, but B1-derived IgA+ cells are IL-5 dependent and IL-6 independent.

Classical eyeblink conditioning in two strains of mice: conditioned responses, sensitization, and spontaneous eyeblinks

Conditioned eyeblink responses (CRs), sensitization, and spontaneous eyeblinks were studied in C57BL/6J and BALB/c mice. Both strains of mice acquired CRs during 10 days of classical delay eyeblink conditioning. The BALB/c mice reached a higher asymptotic CR level than the C57BL/6J mice. The CRs were extinguished and recovered in both strains following conditioned stimulus-alone and paired conditioned stimulus-unconditioned stimulus training. During 10 days of explicitly unpaired training, the control groups showed no signs of sensitization and low incidence of spontaneous eyeblinks. When switched to paired training, the unpaired groups exhibited significant conditioned inhibition. These results suggest that strain differences must be considered in experimental design and data interpretation for these basic aspects of associative learning and memory.

Transgenic mouse models for tumor suppressor genes

The identification and cloning of tumor suppressor genes has mostly relied on familial human cancer predisposition syndromes and reverse genetics. Recent advances in manipulating the mouse genome by gene targeting techniques in embryonic stem (ES) cells has led to the generation of mutant mouse models mimicking many human syndromes. Mice lacking one or both alleles of known tumor suppressor genes have been generated to evaluate the normal function of these genes in vivo. These mice have proven to be highly susceptible to tumor development, indicating that the mouse is a potent in vivo assay system for tumor suppressor genes. The initiation of gonadal tumor development in mice lacking both copies of the alpha-inhibin gene demonstrates that this assay is also useful for identifying new tumor suppressor genes. In the future, murine ES cell/gene targeting strategies will continue to be used to identify novel tumor suppressors and analyze their in vivo roles in growth control.

The relationship of scattered subharmonic, 3.3-MHz fundamental and second harmonic signals to damage of monolayer cells by ultrasonically activated Albunex

Cultured Chinese hamster ovary cells attached to thin Mylar sheets were exposed to 3.3-MHz ultrasound in the presence of Albunex ultrasound contrast agent. The ultrasound beam was directed upward at the exposure chamber with the monolayer on the inside of the upper acoustic window. Cell membrane damage was detected by the firefly enzyme assay for released ATP and the subharmonic, fundamental, and second harmonic scattered signals were recorded. ATP release increased monotonically with increasing pressure amplitude above apparent thresholds of 0.28 MPa for 1-s continuous and 0.56 MPa for 100-s pulsed (10-microseconds pulses, 1-ms PRP) exposures with 5% Albunex. The subharmonic signal and, to a lesser extent, the second harmonic signal both increased with the cell membrane damage, which suggests that these signals have predictive value for bioeffects. If the monolayer was positioned on the front window of the exposure chamber, cell membrane damage was greatly reduced, which confirms the protective influence of this configuration of monolayers reported in the literature. The effect decreased both at high (50%) or low (0.5%) concentrations of Albunex. The strong nonlinear scattering of ultrasound by contrast agent gas bodies appears to provide useful indicators of gas body activity including cavitational bioeffects.

Cardiac defects and altered ryanodine receptor function in mice lacking FKBP12

FKBP12, a cis-trans prolyl isomerase that binds the immunosuppressants FK506 and rapamycin, is ubiquitously expressed and interacts with proteins in several intracellular signal transduction systems. Although FKBP12 interacts with the cytoplasmic domains of type I receptors of the transforming growth factor-beta (TGF-beta) superfamily in vitro, the function of FKBP12 in TGF-beta superfamily signalling is controversial. FKBP12 also physically interacts stoichiometrically with multiple intracellular calcium release channels including the tetrameric skeletal muscle ryanodine receptor (RyR1). In contrast, the cardiac ryanodine receptor, RyR2, appears to bind selectively the FKBP12 homologue, FKBP12.6. To define the functions of FKBP12 in vivo, we generated mutant mice deficient in FKBP12 using embryonic stem (ES) cell technology. FKBP12-deficient mice have normal skeletal muscle but have severe dilated cardiomyopathy and ventricular septal defects that mimic a human congenital heart disorder, noncompaction of left ventricular myocardium. About 9% of the mutants exhibit exencephaly secondary to a defect in neural tube closure. Physiological studies demonstrate that FKBP12 is dispensable for TGF-beta-mediated signalling, but modulates the calcium release activity of both skeletal and cardiac ryanodine receptors.

In vivo transfection of melanoma cells by lithotripter shock waves

The potential for gene transfection during shock wave tumor therapy was evaluated by searching for shock wave-induced DNA transfer in mouse tumor cells. B16 mouse melanoma cells were cultured by standard methods and implanted s.c. in female C57BL/6 mice 10-14 days before treatment. A luciferase reporter vector was used as the DNA plasmid for intratumoral injection at 0.2 mg/ml tumor. Air at 10% of tumor volume was injected after the DNA in some tumors to enhance acoustic cavitation activity. The shock wave generation system was similar to a Dornier HM-3 lithotripter with pressure amplitudes of 24.4 MPa peak positive and 5.2 MPa peak negative. Luciferase production in isolated tumor cells was measured with a luminometer 1 day after treatment to assess gene transfer and expression. Exposure to 800 shock waves, followed by immediate isolation and culture of tumor cells for 1 day, yielded 1.1 (0.43 SE) pg/10(6) cells for plasmid injection only and 7.5 (2.5 SE) pg/10(6) cells for plasmid plus air injection. Significantly increased luciferase production, relative to shams, occurred for 200-, 400-, 800-, and 1200-shock wave treatments with plasmid and air injection. Exposure with the isolation of tumor cells delayed for a day to allow gene expression within the growing tumors gave increased luciferase production for 100- and 400-shock wave exposures without and with air injection. Gene transfer therefore can be induced during lithotripter shock wave treatment in vivo, particularly with enhanced acoustic cavitation, which supports the concept that gene and shock wave therapy might be advantageously merged.

The role of local school quality in rural employment and population growth

"This study investigates the influence of school quality (measured at the high school level) on 1980 to 1990 population and employment change for nonmetropolitan fringe and hinterland census tracts in South Carolina. A Boarnet variation of the Carlino-Mills model is used to examine the interdependence of population and employment change.... Results...indicate that fringe tracts' population growth was positively related to student test scores, and hinterland tracts population and employment growth were negatively related to student-teacher ratios. Empirical results suggest that local school quality provided a positive influence on rural growth, primarily in terms of residential growth. The role of school quality for employment growth was less clear."

Induction of micronuclei in respiratory tract following radon inhalation

Male Wistar rats were exposed to radon and its progeny (0.0, 60, 262 and 564 working level months, WLM), and the frequency of micronuclei was determined in deep lung fibroblasts, and deep lung, trachea and nasal epithelial cells with slopes of 0.28, 0.67, 0.34 and 0.11 micronuclei/1000 binucleated cells/WLM respectively. Micronuclei in deep lung fibroblasts, isolated and cultured using two methods and media, demonstrated no differences in slopes. Biological damage was used as a biodosimeter to calculate the relationship between dosimetric units: alpha particle traversals or 'nuclear hits', dose in mGy and exposure in WLM. The estimated number of nuclear alpha traversals/Gy was 6.3. Radon exposure to 170 WLM resulted in the same frequency of micronuclei in deep lung epithelial cells as produced by one alpha hit/cell nucleus. Absorbed dose/unit of exposure (mGy/WLM) was estimated assuming the damage was related to absorbed dose or to changes in cell sensitivity and ranged from 1.13 to 1.34 for deep lung epithelial cells, 0.47 to 1.09 for deep lung fibroblasts, 0.34 to 0.67 for tracheal epithelial cells and 0.18 to 0.33 for nasal epithelial cells. Biological dosimetry can be used to relate exposure to damage, compare dosimetric units and validate physical dosimetry models. This approach can be applied to any inhaled material capable of producing biological damage.

Presence of functional luteinizing hormone/chorionic gonadotropin (hCG) receptors in human breast cell lines: implications supporting the premise that hCG protects women against breast cancer

We investigated MCF-7 and MDA-MB-231 human breast cancer cell lines and immortalized mammary epithelial HBL-100 cells for the presence of functional LH/hCG receptors. The results revealed that all three breast cell lines contain LH/hCG receptor mRNA transcripts and receptor proteins that can bind 125I-hCG. The MCF-7 cells, however, contain higher levels than the others. Culturing MCF-7 cells with highly purified hCG resulted in a dose- and time-dependent significant decrease in steady-state estradiol receptor mRNA and protein levels as compared to controls, with the maximal decrease occurring after 4 h of culture with 10 ng/ml hCG. The studies on cell growth demonstrated that hCG treatment in the presence of minimal or no fetal bovine serum had a time-dependent significant inhibitory effect on MCF-7 and HBL-100, but not on MDA-MB-231 cells. In summary, our results demonstrate that human breast cell lines contain functional LH/hCG receptors. The hCG effects in MCF-7 cells are consistent with a premise that hCG protects women against breast cancer.

Exercise in transgenic mice overexpressing GLUT4 glucose transporters: effects on substrate metabolism and glycogen regulation

We assessed the effects of GLUT4 glucose transporter expression on substrate metabolism and glycogen regulation during exercise. Transgenic mice overexpressing human (h)GLUT4 in muscle and fat (TG) and their wild-type littermates (WT) were studied by indirect calorimetry at rest and during acute treadmill exercise (30 minutes) and recovery (30 minutes). The rate of carbon dioxide production (VCO2) increased to a greater degree in TG during exercise, whereas resting VCO2, resting oxygen production (VO2), and exercise-induced increments in VO2 were similar in TG and WT. As a result, the respiratory quotient (RQ) was increased by .03 to .05 in TG during exercise, due to greater consumption of carbohydrate (up to approximately 64% more) and less consumption of lipid (up to approximately 40% less) compared with WT, without differences in overall energy expenditure. These differences in substrate metabolism were observed despite relative hypoglycemia and elevated free fatty acids (FFAs) in TG that persisted throughout resting, exercise, and recovery periods. To further assess substrate availability, glycogen content and glycogen synthase activity were measured in skeletal muscle and liver. At rest, muscle glycogen content was 50% higher and glycogen synthase I was 40% lower in TG compared with WT. During exercise and recovery, muscle glycogen was more profoundly depleted in TG than in WT, and glycogen synthase I increased to levels observed in WT, with no change in total glycogen synthase. In the liver, glycogen content and total glycogen synthase were similar in TG and WT under resting conditions, while glycogen synthase I was reduced by 48%. Exercise and recovery induced a more profound depletion of liver glycogen (76% v 30%) and greater increments in both I-form and total glycogen synthase in TG. In conclusion, (1) TG overexpressing GLUT4 exhibit greater muscle glycogen content at rest than WT; (2) during exercise, TG metabolize more carbohydrate, made possible by increased glycogenolysis in muscle and liver, and this predominates as a fuel source despite hypoglycemia and increased availability of FFA; (3) increased carbohydrate metabolism is linked to a decrease in lipid metabolism such that there is no change in overall energy expenditure; and (4) glycogen synthase I activity is inversely proportional to tissue glycogen content despite differences in circulating glucose, insulin, and FFA concentrations, indicating that glycogen content has an overriding regulatory influence on glycogen synthase.

Benefits of angular expression to reconstruction algorithms for collimators with spatially varying focal lengths

Fan-beam collimators with spatially varying focal lengths are used in single photon emission computed tomography (SPECT) to improve the imaging sensitivity and to reduce the reconstruction artifacts resulting from the truncation of projection data. An angular representation of the detector coordinates for the projection data is adopted to investigate several aspects of the reconstruction problem for this type of collimation. A rebinning reconstruction algorithm is derived. We prove a conjecture posed by Zeng and Gullberg and obtain a simplified form of their backprojection filtering algorithm. Some computer simulations are presented to investigate the performance of the rebinning algorithm.

[Determination of trace iron and cobalt in natoral water by ammonium thiocyanate resin phase-spectrophotometry]

At the presence of Tween-80 in acid medium, Fe(III) Co(III) and SCN- are changed into coloured complexations and quantitatively absorbed on the resin. The apparent molar absorptivities of resin phase are epsilon Fe = 2.4 x 10(5)L x mol(-1) x cm(-1) at 490nm and epsilon Co = 2.1 x 10(5)L x mol(-1) x cm(-1) at 630nm by spectrophotometry. Beer's law is obeyed by Fe(III) and Co (III) in the range of 0-8microg/25mL and 0-15microg/25mL. method has been applied to natural water. Relative standard deviations are 1.7% and 5.5%, respectively.

[Studies on arachidonic acid production by Mortierella]

The effects of the incubation temperature, initial pH of the medium, carbon source and nitrogen source on the production of arachidonic acid by Mortierella sp. M10 were studied. Thought orthogonal experiments, the optimum culture medium was obtained (g/L): glucose, 100; yeast extract, 10; KNO3, 4.0; KH2PO4, 2.0; CaCl2.2H2O, 0.1; MgSO4.7H2O, 0.5; FeCl3.6H2O, 0.015; ZnSO4.7H2O, 0.0075; CuSO4.5H2O, 0.0005. Under the optimum culture conditions, the dry cell weight and arachidonic acid was 33.51 g/L and 0.827 g/L, respectively. The flask culture process was analysed.

Associative learning

This chapter reviews evidence demonstrating the essential role of the cerebellum and its associated circuitry in the learning and memory of classical conditioning of discrete behavioral responses (e.g., eyeblink, limb flexion, head turn). It now seems conclusive that the memory traces for this basic category of associative learning are formed and stored in the cerebellum. Lesion, neuronal recording, electrical microstimulation, and anatomical procedures have been used to identify the essential conditioned stimulus (CS) circuit, including the pontine mossy fiber projections to the cerebellum; the essential unconditioned stimulus (US) reinforcing or teaching circuit, including neurons in the inferior olive (dorsal accessory olive) projecting to the cerebellum as climbing fibers; and the essential conditioned response (CR) circuit, including the interpositus nucleus, its projection via the superior cerebellar peduncle to the magnocellular red nucleus, and rubral projections to premotor and motor nuclei. Each major component of the eyeblink CR circuit was reversibly inactivated both in trained animals and over the course of training. In all cases in trained animals, inactivation abolished the CR (and the UR as well when motor nuclei were inactivated). When animals were trained during inactivation (and not exhibiting CRs) and then tested without inactivation, animals with inactivation of the motor nuclei, red nucleus, and superior peduncle had fully learned, whereas animals with inactivation of a very localized region of the cerebellum (anterior interpositus and overlying cortex) had not learned at all. Consequently, the memory traces are formed and stored in the cerebellum. Several alternative possibilities are considered and ruled out. Both the cerebellar cortex and the interpositus nucleus are involved in the memory storage process, suggesting that a phenomenon-like long-term depression (LTD) is involved in the cerebellar cortex and long-term potentiation (LTP) is involved in the interpositus. The experimental findings reviewed in this chapter provide perhaps the first conclusive evidence for the localization of a basic form of memory storage to a particular brain region, namely the cerebellum, and indicate that the cerebellum is indeed a cognitive machine.

Comparative clastogenic sensitivity of respiratory tract cells to gamma rays

To understand the relationships between exposure and damage to different cell populations in the respiratory tract, methods were developed to culture deep-lung fibroblasts and epithelial cells from the nose, trachea and deep lungs. Female F-344 Fischer and male Wistar rats were exposed to 1-5 Gy of 60Co gamma rays at a dose rate of 0.4 Gy/min. Cells were isolated for short-term culture, and the incidences of binucleated cells and micronuclei were determined. The incidences of micronuclei were determined in cytochalasin-B-induced binucleated cells at 72 h for nasal and tracheal tissue and 96 h for deep-lung fibroblasts and epithelial cells. Maximum frequencies of binucleated cells were found in the control nonirradiated cells at these harvest times, and the frequencies were not significantly affected at these harvest times by radiation exposure. No significant differences were found in the frequencies of micronuclei induced in the nasal epithelial cells isolated from female F-344 Fischer or male Wistar rats. Fibroblasts cultured in different media and isolated from either female F-344 Fischer or male Wistar rats also showed a similar frequency of micronuclei. Over the doses tested, the frequency of micronuclei in the respiratory tract cells increased linearly with the dose. The slopes were 92.2 +/- 9.2, 76.2 +/- 7.9, 32.8 +/- 2.4 and 28.7 +/- 3.4 micronuclei/1000 binucleated cells/Gy for deep-lung epithelial cells, deep-lung fibroblasts, tracheal epithelial cells and nasal epithelial cells, respectively. Deep-lung epithelial or fibroblast cells were about two to three times as sensitive for elastogenic damage as nasal and tracheal epithelial cells. The measurement of micronuclei in isolated respiratory tract cells is very useful in assessing cytogenetic damage induced in different cell types by radiation.

Selective enhancement of emotional, but not motor, learning in monoamine oxidase A-deficient mice

Mice deficient in monoamine oxidase A (MAOA), an enzyme that metabolizes monoamines such as norepinephrine and serotonin, have elevated norepinephrine and serotonin levels in the frontal cortex, hippocampus, and cerebellum, compared with normal wild-type mice. Since monoamines in these areas are critically involved in a variety of behaviors, we examined learning and memory (using emotional and motor tasks) in MAOA mutant mice. The MAOA-deficient mice exhibited significantly enhanced classical fear conditioning (freezing to both tone and contextual stimuli) and step-down inhibitory avoidance learning. In contrast, eyeblink conditioning was normal in these mutant mice. The female MAOA-deficient mice also displayed normal species-typical maternal behaviors (nesting, nursing, and pup retrieval). These results suggest that chronic elevations of monoamines, due to a deletion of the gene encoding MAOA, lead to selective alterations in emotional behavior.

Expression of luteinizing hormone/human chorionic gonadotropin receptor gene in benign prostatic hyperplasia and in prostate carcinoma in humans

The findings that normal rat prostates express functional LH/hCG receptors led us to test the hypothesis that benign prostatic hyperplasia (BPH) and prostate carcinomas may also express this receptor gene. The data revealed the presence of LH/hCG receptor transcripts and receptor protein in normal and hyperplastic but not in atrophic glands present in BPH tissue. Smooth muscle and blood vessels in stroma of BPH tissue also contained receptors. Prostate carcinomas contain lower and more heterogeneous receptor levels than BPH tissue. Two human prostate cancer cell lines (LNCaP and DU 145) that were investigated showed the presence of a major 4.5-kilobase transcript and several minor transcripts and also the protein of LH/hCG receptors. However, androgen-sensitive LNCaP cells contained more receptors than androgen-insensitive DU 145 cells. In summary, we demonstrate for the first time that BPH and prostate cancer tissues and cell lines express LH/hCG receptor gene. These findings suggest that higher LH levels in aged men may play a role in BPH and/or prostate carcinomas.

Transfection of a reporter plasmid into cultured cells by sonoporation in vitro

Cultured Chinese hamster ovary cells were exposed to 2.25-MHz ultrasound in sterile 4.5-mL polyethylene chambers and tested for cell lysis, sonoporation and DNA transfection. Ten percent of Albunex, a gas-body-based ultrasound contrast agent, was added to ensure cavitation nucleation, and the chambers were rotated at 60 rpm to promote cavitation activity during the 1-min exposures. Uptake of large fluorescent dextran molecules by some cells was observed for spatial peak pressure amplitudes as low as 0.1 MPa, which indicates transient permeabilization and resealing, i.e., sonoporation, of these cells during exposure. Significant lysis occurred for 0.2 MPa, and increased rapidly for exposures above the apparent cavitation threshold (using the H2O2 production test) of about 0.4 MPa spatial peak pressure amplitude. In the DNA transfection tests, 20 micrograms/mL luciferase reporter plasmid was added to the suspension during exposure, and cells were assayed for proliferation ability and luciferase gene expression 2 days after exposure. Cell proliferation was greatly reduced above the cavitation threshold. Luciferase production was significant for 0.20-MPa exposure, and reached 0.33 ng per 10(6) cells at 0.8-MPa exposure. The luciferase production was great for cells exposed in medium supplemented with serum than for cells exposed in serum-free medium. Cells harvested for exposure either in the log phase or in the stationary phase of culture gave similar proliferation and transfection results. The effects essentially disappeared when the Albunex was omitted from the suspension and the tube was not rotated. Thus, sonoporation by ultrasonic cavitation in the rotating tube system yields plasmid transfection with subsequent transient gene expression.

Regulation of mucosal IgA responses in vivo: cytokines and adjuvants

The predominance of IgA plasma cells at mucosal sites reflects a combination of the selective localisation and vigorous proliferation after extravasation of IgA plasma cell precursors. Experiments are described here which demonstrate that post-extravasation events leading to IgA precursor cell retention, proliferation and antibody secretion are under cytokine control. This has led to investigation of therapeutic interventions to modify cytokine availability to maximise mucosal vaccination responses and correct IgA deficiencies.

Differential expression of interleukin-5 mRNA+ cells and eosinophils in Nippostrongylus brasiliensis infection in resistant and susceptible strains of mice

Interleukin (IL)-5 is produced by both T cells and eosinophils and has been implicated in lymphocyte and eosinophil differentiation and maturation. The extent to which differences in IL-5 expression contribute to genetic variability in parasite immunity was investigated by comparing eosinophilia, IgE production, mastocytosis and IL-5 mRNA+ cells following Nippostrongylus brasiliensis infection of resistant (BALB/c) and susceptible (C57BL/6) mice. In uninfected mice, IL-5 mRNA+ cells detected by in situ hybridization were distributed throughout the lamina propria and crypt regions of the small intestine in both strains, but were 1.5-fold higher in BALB/c than in C57BL/6 mice. Following N. brasiliensis infection, the numbers of IL-5 mRNA+ cells in BALB/c mice continued to increase until day 11 post-infection at which time they were more than 4-fold more numerous than in uninfected control mice of the same strain. In C57BL/6 mice, IL-5 mRNA+ cells reached peak numbers on day 7 post-infection, only 1.5-fold higher than uninfected controls, but the numbers began to decline thereafter. At all time points after day 5, the numbers of IL-5 mRNA+ cells in the gut of C57BL/6 mice were significantly lower than BALB/c mice. The differences in numbers of IL-5 mRNA+ cells induced by infection in each strain of mice correlated with changes in blood and intestinal eosinophilia, mastocytosis and IgE production and was reflected in differences in worm expulsion and egg counts. Although numbers of intestinal IgA-containing cells increased in both strains after infection, there was no difference between strains except at day 11 when there were significantly higher numbers in BALB/c mice than in C57BL/6 mice. These results suggest that IL-5 is an important regulatory factor determining host immunity to parasite infection and that differential regulation of IL-5 expression explains in part the observed strain differences with respect to parasite resistance.

Antigen delivery strategies for mucosal vaccines

Progress towards effective vaccines to control internal parasites, especially those affecting mucosal compartments, has been inhibited by the combined problems of the antigenic complexity of parasites and the lack of understanding of the host response. However, the accumulation of information regarding regulation of mucosal immunity has enabled a reappraisal of vaccination options to provide appropriate mucosal effector responses. The pivotal role of T cell influences, and in particular the contribution of cytokine signals, has been clearly established from in vitro studies, but data emerging from our laboratories provide evidence for these effects in vivo. We have demonstrated the role of T cells in determining the outcome of an intestinal response and propose a role for local Th2 cytokine production in this regard. To support this proposition, the distribution of cytokine mRNA has been determined by in situ hybridisation techniques in normal and parasitised animals. Further, we have shown that in the absence of Th2 cytokines (using gene knockout animals) mucosal responses are grossly deficient; we have also shown that this defect can be overcome by vector-directed gene therapy. These studies have indicated that new mucosal immunisation opportunities exist by combining traditional immunisation approaches with strategies to upregulate local cytokine production. However, the success of these new strategies will depend on selection of highly immunogenic subunit antigens, coupled with techniques for cytokine manipulation and delivery with appropriate adjuvant/vehicle formulations. This paper reviews delivery technologies available to chaperone labile antigenic and genetic material to appropriate sites for mucosal stimulation after systemic or oral administration.

Impaired classical eyeblink conditioning in cerebellar-lesioned and Purkinje cell degeneration (pcd) mutant mice

Converging lines of evidence from rabbits, rats, and humans argue for the crucial involvement of the cerebellum in classical conditioning of the eyeblink/nictitating membrane response in mammals. For example, selective lesions (permanent or reversible) of the cerebellum block both acquisition and retention of eyeblink conditioning. Correspondingly, electrophysiological and brain-imaging studies indicate learning-related plasticity in the cerebellum. The involvement of the cerebellum in eyeblink conditioning is also supported by stimulation studies showing that direct stimulation of the two major afferents to the cerebellum (the mossy fibers emanating from the pontine nucleus and climbing fibers originating from the inferior olive) can substitute for the peripheral conditioned stimulus (CS) and unconditioned stimulus (US), respectively, to yield normal behavioral learning. In the present study, we examined the relative contribution of the cerebellar cortex versus deep nuclei (specifically the interpositus nucleus) in eyeblink learning by using mutant mice deficient of Purkinje cells, the exclusive output neurons of the cerebellar cortex. We report that Purkinje cell degeneration (pcd) mice exhibit a profound impairment in the acquisition of delay eyeblink conditioning in comparison with their wild-type littermates. Nevertheless, the pcd animals did acquire a subnormal level of conditioned eyeblink responses. In contrast, wild-type mice with lesions of the interpositus nucleus were completely unable to learn the conditioned eyeblink response. These results suggest that both cerebellar cortex and deep nuclei are important for normal eyeblink conditioning.

[Long-term investigation of closed reduction of congenital hip dislocation in children with modified frog-leg cast]

From 1978 to 1983, closed reduction and fixation with frog-leg cast were used to treat congenital hip dislocation in children in our hospital. Sixty-two patients with such hip dislocation were treated by these methods. Among them 38 patients under 3 years of age were followed up for 12 to 16 years (mean 13 years). Encouraging results were obtained and the reduction rate was 97.9%. This treatment revealed that after closed reduction the fixation and the slight movement of the femoral head in the cast under the fixation are a self-remould action that may promote the growth of the acetabulum and the femoral head resulting in normal development of the hip.

Ergonomic effects of a management-based rationalization in assembly work - a case study

Due to unsatisfactory productivity, a large company in the Swedish manufacturing industry decided to rationalize their assembly system. The intended rationalization comprised several changes with deliberate ergonomic implications. The main aim of the present study was to evaluate the impact of the rationalization on the physical work load of the operators. The work load was assessed before and after the changes using expert observations, company records and direct technical measurements. The results indicate that the intervention led to only minor changes in muscle load, body postures and movement patterns. Several of the planned initiatives were never implemented, e.g. teaching the workers multiple skills and designing work stations at which a major part of the assembly sequence could be performed. This was mainly due to a policy revision caused by changes in the market situation. In spite of the company's original intentions, the revised production system contained only minor ergonomic improvements. Thus, the realization of the ergonomic potential in a rationalization seems to depend on management culture, as well as factors outside the company.

Preclinical evaluation of SPECT imaging with 131I-labeled monoclonal antibody SZ39 in nude mice bearing human glioma xenografts

The imaging characteristics of monoclonal antibody SZ39 against glioma were evaluated in glioma-bearing nude mice. Monoclonal antibody SZ39 is a murine IgG2a that reacts with a glycoprotein epitope (molecular weight 180,000), a human glioma-associated membrane antigen. Monoclonal antibody SZ39 was labeled with 131I using a modified chloramine T method. Each glioma-bearing nude mouse was given 50 microCi/40 micrograms of the experimental agent, 131I-labeled monoclonal antibody, or 50 microCi/46 micrograms of a control agent, 131I-labeled monoclonal antibody C50, an antibody against colon cancer. Single-photon emission computed tomography (SPECT) was performed every 24 hours in the first week after administration. Glioma-bearing nude mice were killed in groups of 3 at 24 hours and daily up to 72 hours. The ratio of radioactivity uptake in glioma to normal organs was calculated. After administration of the labeled SZ39, glioma was visualized with SPECT on days 1 to 7, particularly at 72 hours. There was no accumulation of radioactivity in glioma with the labeled C50 antibody. All glioma-organ ratios increased with time. At 72 hours, the ratio of glioma to brain was 22.46 and of the other organs was 2.64 on average. SZ39 had a relatively low endocytosis rate and was favorable for 131I labeling. These characteristics were helpful to reduce free 131I in the blood and reduce the uptake by other organs. The results suggest that 131I-labeled SZ39 selectively accumulates in glioma, representing a potential strategy for SPECT imaging of these lesions.

Deficient cerebellar long-term depression, impaired eyeblink conditioning, and normal motor coordination in GFAP mutant mice

Mice devoid of glial fibrillary acidic protein (GFAP), an intermediate filament protein specifically expressed in astrocytes, develop normally and do not show any detectable abnormalities in the anatomy of the brain. In the cerebellum, excitatory synaptic transmission from parallel fibers (PFs) or climbing fibers (CFs) to Purkinje cells is unaltered, and these synapses display normal short-term synaptic plasticity to paired stimuli in GFAP mutant mice. In contrast, long-term depression (LTD) at PF-Purkinje cell synapses is clearly deficient. Furthermore, GFAP mutant mice exhibited a significant impairment of eyeblink conditioning without any detectable deficits in motor coordination tasks. These results suggest that GFAP is required for communications between Bergmann glia and Purkinje cells during LTD induction and maintenance. The data support the notion that cerebellar LTD is a cellular mechanism closely associated with eyeblink conditioning, but is not essential for motor coordination tasks tested.

Interleukin-5 mRNA expressed by eosinophils and gamma/delta T cells in parasite-immune sheep

Interleukin (IL)-5 is produced by variety of cell types and contributes to both lymphocyte development an eosinophil terminal differentiation in vitro. The coincidence of worm expulsion and eosinophilia in sheep infected with the gastrointestinal nematode Trichostrongylus colubriformis suggest that eosinophils may be involved as effector cells in host immunity against parasite infection. The role of IL-5 in this process was investigated by observing the distribution of IL-5 mRNA+ cells in the small intestine, mesenteric lymph nodes (MLN) and Peyer's patches (PP) by an in situ hybridization technique using a murine IL-5 riboprobe. IL-5 mRNA+ cells were distributed throughout the lamina propria (LP) of the small intestine from the tips of the villi to the muscularis mucosae and in the parafollicular areas of MLN and PP in both naive and immune sheep. The phenotypes of IL-5 mRNA+ cells was explored by simultaneous eosin and immunohistochemical staining using a monoclonal antibody recognizing the T19 marker, which identifies a major subset of gamma/delta TCR+ cells in sheep. In immune sheep, there was about a five-fold increase in the number of eosinophils and IL-5 cell mRNA+ cells in the LP, but there was no significant change in numbers of T19+ cells. Most of the IL-5 mRNA cells in the LP were eosinophils, but many of the T19+ cells also expressed IL-5 mRNA. In contrast, there were fewer eosinophils than T19+ cells in MLN of immune sheep and, compared to controls, a three-fold increase in T19+ cells and a five-fold increase in T19+/IL-5 mRNA+ double positive cells observed in immune sheep. In PP, there were very few eosinophils but substantial numbers of T19+ cells; however, no significant differences in numbers of eosinophils, T19+ or IL-5 mRNA+ cells were observed between control and immune sheep. These results indicate that in sheep, both eosinophils and gamma/delta T cells are capable of IL-5 expression and suggest that IL-5 is an important regulatory factor in autocrine and paracrine activation of effector cells involved in parasite immune expulsion.

[Ion-selective microelectrodes: principle and application of in vivo measurements of ionic concentrations in cochlear endolymph]

OBJECTIVE

To introduce the method of making neutral carrier ion-selective microelectrode and use it for in vivo measurement of ionic concentrations in cochloear endolymph.

METHODS

GG-17 glass capillaries with 1.85 mm O.D. were rinsed extensively and dried in an oven. Two capillaries were parallelly connected and pulled with microelectrode puller to make a double-barreled micropipette. One barrel was back-filled with ion exchanger and internal reference solution, which served as ionic potential electrode, while the other barrel filled with 150 mmol/L KCL as reference electrode. Each barrel of microelectrode was connected to differential electrometer via Ag-AgCl wire and output was recorded on a three-channel recorder. Every ion-selective microelectrode was calibrated in a series of standard solutions to determine the required characteristics. Twenty healthy guinea pigs with normal hearing were anesthetized and were artificially respired through the tracheal canal after the intramuscular injection of suxamethonium chloride. The tympanic bulla was exposed and a double-barreled ion-selective electrode was inserted into the scala media through the round window and basilar membrane. The ionic potentials and endocochlear potentials (EP) were simultaneously recorded from the basal turn of the cochlea. Ionic concentrations were then calculated by Nicolsky-Eisenman equation.

RESULTS

The concentrations of potassium, sodium and calcium ions in the cochlear endolymph were 146.3 +/- 11.8 mmol/L, 0.36 +/- 0.22 mmol/L and 16.2 +/- 5.7 micromol/L, respectively.

CONCLUSIONS

The neutral carrier ion-selective microelectrode made with the above method is reliable and therefore can be used for accurately measuring the ionic concentrations of microenvironment in vivo continuously and transiently.

DNA damage, micronucleus formation, and cell death from 125I decays in DNA

CHO cells were pulse-labeled with 125I-iododeoxyuridine, harvested 30 min or 5 h after labeling, and stored at -196 degrees C for accumulation of 125I decays. The 30- min groups yielded low-LET survival curves (large shoulder, D0 136 decays/cell); 5-h groups showed a high-LET pattern of cell killing (no shoulder, D0 45 decay/cell). Surprisingly, the shift in 125I action was abolished in cells exposed to HAT medium; both 30-min and 5-h cell groups exhibited high-LET-type killing (no shoulder, D0 52 decays/cell). The striking difference in cell death was not accompanied by any change in induction or repair of DNA DSBs, but the pattern of micronucleus formation (and by implication chromosome damage) did parallel 125I-induced cell death. These findings suggest that cell killing may not be directly linked to the absolute number of DNA DSBs and that damage to higher-order genome structures may be an important factor in radiation-induced cell death.

Impaired motor coordination correlates with persistent multiple climbing fiber innervation in PKC gamma mutant mice

It is generally believed that a smooth execution of a compound movement, or motor coordination, requires learning of component movements as well as experience-based refinement of the motor program as a whole. PKC gamma mutant mice display impaired motor coordination but intact eyeblink conditioning, a form of component movement learning. Cerebellar long-term depression, a putative cellular mechanism for component motor learning, is also unimpaired. Thus, PKC gamma mutant mice are defective in refinement of the motor program. In the accompanying paper, we demonstrate that innervation of multiple climbing fibers onto Purkinje cells persists in adulthood in these mutant mice. We propose that this defective elimination of surplus climbing fibers underlies motor discoordination.

The effects of brefeldin A on the glucose transport system in rat adipocytes. Implications regarding the intracellular locus of insulin-sensitive Glut4

Insulin activates glucose transport by recruiting Glut4 glucose transporters from an intracellular pool to plasma membrane (PM). To localize intracellular translocating Glut4, we studied the effects of brefeldin A (BFA), which disassembles Golgi and prevents trans-Golgi vesicular budding, on the glucose transport system. Isolated rat adipocytes were treated with and without both BFA (10 micrograms/ml) and insulin. BFA did not affect maximal rates of either 2-deoxyglucose or 3-O-methyl-glucose transport or the insulin:glucose transport dose-response curve but did increase basal transport by approximately 2-fold (p < 0.05). We also measured Glut4 in PM, low (LDM) and high density microsome subfractions. In basal cells, BFA increased PM Glut4 by 58% concomitant with a 18% decrease in LDM (p < 0.05). Insulin alone increased PM Glut4 by 3-fold concomitant with a 56% decrease in LDM. BFA did not affect insulin-induced changes in Glut4 levels in PM or LDM. Most intracellular Glut4 was localized to sub-PM vesicles by immunoelectron microscopy in basal cells, and BFA did not affect insulin-mediated recruitment of immunogold-labeled Glut4 to PM. In summary, 1) in basal cells, BFA led to a small increase in glucose transport activity and redistribution of a limited number of transporters from LDM to PM; 2) BFA did not affect insulin's ability to stimulate glucose transport or recruit normal numbers of LDM Glut4 to PM; and 3) insulin action is predominantly mediated by a BFA-insensitive pool of intracellular Glut4, which localizes to sub-PM vesicles. Thus, the major translocating pool of Glut4 in rat adipocytes does not involve trans-Golgi.

Ubiquitin fusion proteins are overexpressed in colon cancer but not in gastric cancer

A cDNA clone (AF3) encoding the ubiquitin A gene 52 amino acid extension fusion protein (UbA52) was isolated from a subtracted cDNA library of human colorectal carcinoma minus adjacent normal mucosa. In Northern hybridization the mRNA signal for UbA52 was greater in surgical samples of colonic carcinoma (T) than in paired adjacent normal (N) tissues in 24 of 29 cases (T/N = 3.4 +/- 0.5, P < 0.01). An oligonucleotide probe specific for only the 52 amino acid extension confirmed the overexpression of UbA52. In contrast, there was no overexpression of UbA52 mRNA in gastric cancer samples (n = 7, T/N = 1.0 +/- 0.3). The mRNA of several ribosomal proteins, and of another ubiquitin A gene fusion protein, UbA80, with an 80 amino acid extension of ribosomal protein S27a, have been reported to be over-expressed in colon cancer, but not as yet at the protein level. Using rabbit antisera to the ribosomal protein component S27a we demonstrate over-expression of S27a at the protein level in colonic (n = 5), but not gastric (n = 6) carcinomas. Therefore it is likely that both UbA80 and UbA52 are overexpressed in colon cancer, but not in gastric cancer.

Cytokine mediated effects in mucosal immunity

The predominance of IgA antibodies in mucosal sites reflects a combination of high rate IgA isotype switching among precursor cells in induction sites, their selective localization in mucosal effector tissues and vigorous proliferation of these cells after extravasation. Each of these steps leading to IgA expression at the mucosa is under cytokine control. This paper will address the role of cytokines in induction and expression of IgA responses and strategies for manipulating cytokine expression. Therapeutic interventions based on this information may not only lead to improved vaccination responses and correction of immunodeficiencies but also, by invoking the phenomenon of oral tolerance, may assist in the management of autoimmune, allergic and alloreactive disease.

Analysis of feline dual lymphocyte populations observed by flow cytometry

Two discrete lymphocyte populations were observed commonly on flow cytometric analysis (FCM) of feline lymphocyte subsets. The identity of these populations as small and large lymphocytes was established by correlating data from FCM with that from peripheral blood films. Dual lymphocyte populations were more likely to be seen in feline immunodeficiency virus-positive (FIV(-)+ ve) cats but their occurrence was not affected by health status, age, gender or breed. FIV(-)+ ve cats had a significantly higher proportion of large lymphocytes than FIV-negative (FIV(-)- ve) cats. However, FIV(-)+ ve cats had significantly fewer small lymphocytes than FIV(-)- ve cats but similar numbers of large lymphocytes. Lymphocyte subset analysis revealed that small lymphocytes had a greater proportion of CD4+ cells than large lymphocytes, regardless of the FIV or health status of the cat. In FIV(-)- ve cats, small lymphocytes had a greater proportion of Pan T + lymphocytes than large lymphocytes, but the converse was seen in FIV(-)+ ve cats. The proportion of CD8 + cells was higher in small lymphocytes than large lymphocytes in well FIV(-)- ve cats but this distinction was not seen in sick FIV(-)- ve cats or FIV(-)+ ve cats of any health status. Regardless of health status, FIV(-)+ ve cats had a lower absolute count of small lymphocytes which were T cells (due to lower numbers of both CD4 + and CD8 + cells) than FIV(-)- ve cats. The numbers of small B cells were similar for both FIV(-)+ ve and FIV(-)- ve cats. However, there were no differences between FIV(-)+ ve and FIV(-)- ve cats in the absolute values of any subset of the large lymphocytes, which suggested that FIV may affect only small lymphocytes. Statistically, the inclusion or exclusion of the large lymphocyte population for routine lymphocyte subset analysis did not affect the overall results. However, because there were significant differences in subset distribution between small and large lymphocytes, analysis of both groups should be included in studies examining the role of lymphocytes in disease.

IgA production by peritoneal cavity B cells is IL-6 independent: implications for intestinal IgA responses

We have shown previously both in vitro and in vivo that IL-6 is an important factor for the development of IgA-producing B cells. However, despite the lack of this cytokine in mice with targeted disruption of the interleukin (IL)-6 gene (gene knockout mice), a substantial number of IgA-producing plasma cells occur in their intestinal mucosa. The experiments reported here indicate that there is a population of IgA-producing B cell precursors originating from the peritoneal cavity, distinguished from conventional Peyer's patch-derived precursors by their expression of CD5, and that IgA secretion by these cells is IL-6-independent. Further, there is an increase in CD5 expression among brightly staining IgA-producing cells obtained from the intestinal lamina propria of IL-6 gene-disrupted mice compared to normal controls. These data suggest an explanation for the persistence of IgA-producing plasma cells in the intestinal mucosa of IL-6-depleted mice and indicate the importance of IL-6 for development of conventional precursors of IgA-producing B cells, but not those derived from the peritoneal cavity pool.

Ontogeny of major histocompatibility complex antigen expression on cultured human embryonic skeletal myoblasts

Human embryonic myoblasts isolated from 13- to 19-week embryos were treated for 24 to 144 hr with 0.1-500 U/ml IFN-gamma and the constitutive and IFN-gamma-inducible MHC expression was examined by flow cytometry. Low levels of constitutive MHC I were expressed that increased with both developmental age and incubation time. In contrast, no constitutive MHC II was detected on human embryonic myoblasts at any age or incubation time. Both classes of MHC can be induced by IFN-gamma. Maximal MHC I induction increased in parallel with age, i.e., maximal induction occurred on 19-week myoblasts, while MHC II induction peaked at 17 weeks. IFN-gamma-induced expression of MHC I and II also increased with incubation time. Induced expression of MHC I antigen reached plateau levels at 72 hr of IFN-gamma incubation, whereas MHC II increased to a plateau level at 120 hr. The immunological importance of these findings for myoblast transfer therapy is discussed.

Molecular cloning of chick cardiac muscle tensin. Full-length cDNA sequence, expression, and characterization

Here we describe the molecular cloning of 7.1-kilobase cDNA encoding chick cardiac muscle tensin. It contains an open reading frame of 1,744 amino acid (aa) residues. Sequence analysis reveals that, in addition to the previously noted SH2 domain (Davis, S., Lu, M. L., Lo, S. H., Lin, S., Butler, J. A., Druker, B. J., Roberts, T. M., An, Q., and Chen, L. B. (1991) Science 252, 712-715), tensin contains virtually all of the known sequence (362 aa) of insertin, an actin-capping protein that allows actin monomer to be "inserted" (Schroer, E., and Wegner, A. (1985) Eur. J. Biochem. 153, 515-520). Moreover, tensin shares partial homology with actin (46.7% identity in 30 aa), beta-spectrin's actin-binding consensus (40% identity in 26 aa), BCR (40% identity in 25 aa), catenin alpha (35% identity in 45 aa), synapsin Ia (25.6% identity in 156 aa), IL-3 receptor (20.2% identity in 384 aa), and IL-2/EPO receptors (14% identity in 20 aa). Recombinant full-length tensin, tagged with an influenza-derived epitope, was over-expressed by a baculovirus system and purified to apparent homogeneity. It migrates as a 200-kDa protein in SDS-polyacrylamide gel electrophoresis, similar to the native tensin. The structure of the tensin molecule has been characterized by light scattering, electron microscopy, and gel filtration. Nine monoclonal antibodies recognizing different regions of tensin have been prepared and characterized. The epitope-tagged recombinant tensin gene was subcloned into a pRcCMV vector and transfected into NIH 3T3 cells. Immunofluorescence stainings with monoclonal antibodies specific for chick tensin (not cross-reactive with mouse tensin) showed that the expressed protein is indeed localized at focal contacts, as that of native tensin.

The role of interleukin-6 in mucosal IgA antibody responses in vivo

In mice with targeted disruption of the gene that encodes interleukin-6 (IL-6), greatly reduced numbers of immunoglobulin A (IgA)-producing cells were observed at mucosae and grossly deficient local antibody responses were recorded after mucosal challenge with either ovalbumin or vaccinia virus. The IgA response in the lungs was completely restored after intranasal infection with recombinant vaccinia viruses engineered to express IL-6. These findings demonstrate a critical role for IL-6 in vivo in the development of local IgA antibody responses and illustrate the effectiveness of vector-directed cytokine gene therapy.

Na(+)-dependent high affinity uptake of L-glutamate in primary cultures of human fibroblasts isolated from three different types of tissue

Cultured human fibroblasts isolated from embryonic muscle, skin and peripheral nerve tissues were found to accumulate [3H]L-glutamate by a Na(+)-dependent uptake process strongly inhibited by several glutamate/aspartate analogues including D- and L-aspartate, D- and L-threo-3-hydroxyaspartate and L-trans-pyrrolidine-2,4-dicarboxylate but not D-glutamate. It was also reduced by elevated concentrations of K+, Rb+ and Cs+. The values of Km's were 5-20 microM, well within the 'high affinity' region. Variations in the capacity (Vmax) of [3H]L-glutamate uptake did not correlate with the origin (muscle, skin or nerve tissue) of the fibroblasts. The uptake characteristics suggest that it is mediated by a transport system similar to that commonly observed only in brain tissue.

Cytokine regulation of mucosal responses: a rational basis for new vaccine delivery strategies

In this review, cytokine regulation of mucosal responses is discussed in relation to the mucosal immune network and regulation of IgA responses. Based on this understanding, aspects of gene therapy for manipulation of the host environment and vaccine delivery systems are discussed. Although evidence obtained in vitro is briefly reviewed the general focus of this article is on evidence obtained from models in vivo.

Biological actions of insulin are differentially regulated by glucose and insulin in primary cultured adipocytes. Chronic ability to increase glycogen synthase activity

We have shown previously that prolonged exposure to insulin and glucose impairs the insulin-responsive glucose transport system in primary cultured adipocytes. To assess the ability of insulin and glucose to regulate other cellular insulin actions, epididymal rat adipocytes were cultured in media containing 0-15 mM D-glucose and with or without insulin (50 ng/ml). After 24 h, cells were washed and basal and maximally insulin-stimulated rates of 2-deoxy-D-glucose uptake, L-leucine incorporation into protein, glucose oxidation to CO2, glucose incorporation into lipids, and glycogen synthase activity were measured. The results confirmed that glucose potentiates insulin's chronic ability to decrease basal and maximal glucose transport rates by approximately 50% at 5 mM glucose and by approximately 70% at 15 mM glucose compared with control cells. However, neither glucose nor insulin, alone or in combination, affected rates of leucine incorporation into protein. In addition, basal and maximal rates of glucose oxidation and of glucose incorporation into lipids were not regulated by glucose, and maximal responses declined approximately 50% over 24 h only when insulin was not present during preincubation (i.e., chronic insulin exposure was necessary to maintain full maximal responses). Glycogen synthase activity was measured in a cell-free system (0.5 mM UDP-glucose, with 10 or 0.01 mM glucose-6-phosphate) after exposing intact cells to glucose and insulin. Both short-term (1 h) and long-term (24 h) exposure to glucose alone led a dose-dependent increase in I-form and D-form glycogen synthase activity. Chronic exposure to insulin also increased total glycogen synthase activity (I- plus D-form) but did not affect absolute rates of maximally stimulated I-form activity. Glucose (but not insulin) increased the cellular content of immunoreactive glycogen synthase by 70% after 1 h. These results show that 1) chronic exposure to glucose and insulin impairs insulin responsiveness of the glucose transport system but does not affect rates of amino acid incorporation into protein; 2) the chronic presence of insulin is necessary for the maintenance of normal maximally stimulated rates of glucose oxidation and of glucose incorporation into lipids in cultured cells; and 3) glucose increases both D-form and I-form glycogen synthase activity, in part by increasing the amount of synthase protein, whereas chronic insulin exposure increases total glycogen synthase activity without altering maximal absolute rates of I-form activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of IFN-gamma and IL-6 mRNA in murine intestine by in situ hybridization

Previous studies have highlighted the importance of CD4+ T cells in regulation of IgA responses and have indicated a functional heterogeneity among these cells between inductive (Peyer's patch) and effector (lamina propria) sites in the intestine. To determine whether these functional differences could be accounted for by differences in cytokine profile of cells in each of these sites, the distribution of mRNA for interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) was investigated by in situ hybridization techniques using 35S-labelled riboprobes. Whereas message for IL-6 is abundant in all regions of the lamina propria from the base of the mucosa to the tips of the villi, very little is expressed in Peyer's patches or in the epithelium. In contrast, message for IFN-gamma is expressed predominantly by cells localized only in the base of the lamina propria and, as with IL-6, very little message was detected in Peyer's patches although occasional strongly positive IFN-gamma cells were observed in the epithelium. These results indicate that, at least in the absence of deliberate intestinal stimulation, functional expression of these cytokines is restricted to effector rather than induction sites in the intestine. This is consistent with our previous observations demonstrating a requirement for T-cell signals in promoting post-extravasation differentiation and proliferation of IgA-committed B cells in vivo and the implications of these findings to the role of the Th1 and Th2 subsets of CD4+ cells in mucosal immune responses is discussed.

Structure of parasternal intercostal muscles in the adult hamster: topographic effects

The parasternal intercostals are primary inspiratory muscles like the costal and crural diaphragm. However, the structure of the rib cage and its impedance to inspiration and expiration varies regionally. We questioned whether topographic differences in rib cage structure and impedance were associated with regional differences in parasternal intercostal muscle structure. Therefore, we examined the size and percentage of histochemically stained fibers in the parasternal intercostal muscles in the first, second, third, fourth, and sixth interspaces in the hamster. We observed a rostrocaudal gradient in the percentage and size of slow oxidative (SO), fast oxidative-glycolytic, and fast glycolytic (FG) fibers in the parasternal intercostal muscles. In particular, the percentage of SO decreased while the percentage of FG increased in a rostrocaudal direction in the first through sixth interspaces. In addition, the size of SO and FG fibers increased from the first to sixth interspace. Furthermore, changes in the size and percent of the three fiber types produced, in a rostrocaudal direction, significant reductions in the relative mass of the parasternal intercostal muscle made up of SO fibers and increases in the mass of fast fibers. We speculate that topographical differences in the size and percentage of fast and slow twitch fibers in the parasternal intercostal are likely to alter force-generating capacity of the parasternal muscles in a rostrocaudal direction and likely reflect regional differences in muscle load and/or activity.

Flavivirus induces MHC antigen on human myoblasts: a model of autoimmune myositis?

Infection of human embryonic myoblasts by West Nile virus (WNV), a flavivirus, caused significant upregulation of class I and II MHC expression as determined by flow cytometry. After 48 hours at a multiplicity of infection of 5 pfu/cell, a sixfold increase in MHC class I expression was induced from initially low levels of expression. In contrast, MHC class II was induced de novo to five times the control fluorescence level. At least 70% of the cells were infected as determined using fluorescence microscopy and anti-WNV antibody labeling. Myoblasts were > 90% pure as shown by anti--Leu-19 labeling. MHC class I (but not class II) was increased threefold after exposure to virus-inactivated supernatant from 48-hour--infected cells, indicating the presence of factor(s) contributing to the MHC class I increase. These findings may be important in establishing a link between viral infection of human cells and induction of inflammatory autoimmune disease. We discuss the possibility of using WNV as an in vivo model.

Increased expression of human ribosomal phosphoprotein P0 messenger RNA in hepatocellular carcinoma and colon carcinoma

To search for differentially expressed gene products in selected cancers of endodermal origin, cDNA libraries derived from mRNA in human hepatocellular carcinoma and adjacent grossly normal tissue were generated. From these parent libraries, subtracted cDNA libraries of tumor minus normal and normal minus tumor tissues were constructed. After screening these subtracted libraries by +/- hybridization, a cDNA clone that is overexpressed in hepatocellular carcinoma and encodes the human acidic ribosomal phosphoprotein P0 (P0) was identified. We then evaluated the expression of this phosphoprotein P0 in human colon carcinoma samples. Surgical specimens of primary tumors and liver metastases were examined by Northern hybridization of total RNA with one of 2 32P-labeled P0 probes. The mRNA level of the P0 was greater in primary colon carcinoma than in paired adjacent normal colonic epithelium in 36 of 38 cases; the mean tumor/normal ratio was 2.7 (range, up to 13). The tumor/normal ratio, when plotted against the Dukes' stage of disease, gave evidence for increasing P0 expression with increasing stage of colon carcinoma (P = 0.02). In all 8 cases of paired colon carcinoma metastatic to liver and 2 cases of paired primary hepatocellular carcinoma, the P0 mRNA level was greater in tumor than in adjacent normal liver tissue. The mean tumor/normal ratio was 4.0 (range, up to 11) for the colon cancers metastatic to liver and 4.2 for the primary hepatocellular carcinoma samples. These findings support a common increased expression of selected gene products in different tumors of endodermal origin and suggest that increased P0 expression, in line with certain other ribosomal proteins, may be associated with human colorectal cancer progression and biological aggressiveness.

[Experimental and clinical studies of using Nd: YAG laser via domestic metal cap and sapphire tip delivery systems]

Sixteen segments of normal human cadaver aorta were irradiated by Nd: YAG laser beam delivered via domestic metal cap and sapphire tip fiber systems. Results revealed that the adherence to target tissue and tissue damage were more apparent with metal caps than those with sapphire tips. Furthermore, the latter had smoother edges of ablation crater less carbonization layers and smaller thermal necrotic zones. The delivery systems were used to perform laser angioplasty in 2 iliac and 5 coronary atherosclerotic arteries and all achieved immediate recanalization.