Neural Transplantation of Cells Expressing the Anti-Apoptotic Gene Bcl-2

Long-term survival of grafted neural cells is a major goal of neural transplantation, but typical survival rates of grafted fetal neurons are in the range of 5-10%. Whether the death of transplanted neural cells is apoptotic or necrotic is unknown. The expression of the proto-oncogene bcl-2 inhibits both apoptotic and necrotic neural cell death. In a 6-OHDA induced rat model of Parkinson's disease, Hoechst 33258 prelabelled conditionally immortalized nigral cells engineered to express bcl-2 were stereotactically transplanted into the striatum ipsilaterally to the lesioned nigrostriatal pathway. Sixteen rats received bcl-2 transfected cells, 15 received cells transfected with vector alone, and 12 received either a nondopaminergic cell line or were sham transplanted as controls. Four wk following transplantation, the rats with grafts containing bcl-2 expressing cells showed an approximately 43% decrease in apomorphine-induced rotational behavior. In contrast, 12% improvement occurred in the rats with transplanted cells transfected with vector alone (p < 0.05), and no improvement occurred in sham-operated animals (p < 0.05). Histological examination showed no tumor formation. Despite the difference in behavioral effect, no clear difference in Hoechst fluorescent staining or staining for TH, GFAP was noted; therefore, it is unknown at present whether the observed effect was due to a difference in survival or to increased efficacy per surviving transplanted neural cell, or both.

Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

Site-directed mutagenesis of amino acids in the cytoplasmic loop 6/7 of Na,K-ATPase

The loop between transmembrane helices 6 and 7 (L6/7) of P-type ATPases has been suggested to be important for the functional linkage of ion binding and enzyme phosphorylation or to be a site of initial cation binding. To investigate the role of L6/7 in Na,K-ATPase, alanine substitutions were made for charged and conserved residues in L6/7 of the human alpha1 subunit and the proteins were expressed in yeast for analysis. All mutants except the triple mutant E825A/E828A/D830A bound ouabain. Although the equilibrium dissociation constant for ouabain binding by most mutants was similar to the wild-type value, the K(d) of R837A for ouabain binding was approximately 15-fold higher than the wild-type K(d). (18)O exchange measurements indicated that the apparent affinity of this mutant for Pi was reduced about 3-fold. The concentration dependence of KCl inhibition of ouabain binding or of NaCl inhibition of ouabain binding revealed 2-4-fold changes in the apparent affinity for cations in the E825A, E828A, and R837A mutants. The E825A and E828A mutants lost the ability to bind ouabain after extraction with 0.1% SDS or after brief heating, indicating that these mutations affected the stability of the enzyme. The ATPase activity of the other mutants was measured after extraction of crude yeast membranes with 0.1% SDS. For all mutants except R834A, R837A, and R848A, the activity was at least 50% of wild-type activity.

18O-Exchange Evidence That Mutations of Arginine in a Signature Sequence for P-Type Pumps Affect Inorganic Phosphate Binding†

We have proposed a model for part of the catalytic site of P-type pumps in which arginine in a signature sequence functions like lysine in P-loop-containing enzymes that catalyze adenosine 5'-triphosphate hydrolysis [Smirnova, I. N., Kasho, V. N., and Faller, L. D. (1998) FEBS Lett. 431, 309-314]. The model originated with evidence from site-directed mutagenesis that aspartic acid in the DPPR sequence of Na,K-ATPase binds Mg(2+) [Farley, R. A., et al. (1997) Biochemistry 36, 941-951]. It was developed by assuming that the catalytic domain of P-type pumps evolved from enzymes that catalyze phosphoryl group transfer. The functions of the positively charged amino group in P-loops are to bind substrate and to facilitate nucleophilic attack upon phosphorus by polarizing the gamma-phosphorus-oxygen bond. To test the prediction that the positively charged guanidinium group of R596 in human alpha(1) Na,K-ATPase participates in phosphoryl group transfer, the charge was progressively decreased by site-directed mutagenesis. Mutants R596K, -Q, -T, -M, -A, -G, and -E were expressed in yeast membranes, and their ability to catalyze phosphorylation with inorganic phosphate was evaluated by following (18)O exchange. R596K, in which the positive charge is retained, resembled the wild type. Substitution of a negative charge (R596E) resulted in complete loss of activity. The remaining mutants with uncharged side chains had both lowered affinity for inorganic phosphate and altered phosphate isotopomer distributions, consistent with increased phosphate-off rate constants compared to that of the wild type. Therefore, mutations of R596 strengthen our hypothesis that the oppositely charged side chains of the DPPR peptide in Na,K-ATPase form a quaternary complex with magnesium phosphate.

Electric-field-induced second-harmonic generation in GaN devices

Electric-field-induced second-harmonic generation is used to detect electric fields in a GaN UV Schottky photodiode and in a GaN light-emitting diode. The second-harmonic signal is measured as a function of bias voltage and incident laser power. This technique is sensitive to small applied voltages and can be used to track electronic waveforms. The photocurrent generated by this technique is found to be less than 100 pA when the fundamental and second-harmonic frequencies are both below the device bandgap.

Psoriatic arthritis joint fluids are characterized by CD8 and CD4 T cell clonal expansions appear antigen driven

The CD8 alphabetaT cell receptor repertoire in joint fluid of individuals with active psoriatic arthritis contained an average of 32 major oligoclonal expansions in many variable genes of the TCR beta chain (BV) families, as shown by beta-chain CDR3 length analysis. Interestingly, a small number of oligoclonal expansions were shared between simultaneous samples of joint fluid and blood; however, most expansions found in joint fluid were not identifiable in blood emphasizing the immunologic specificity of the clonal events for the inflamed joint at a given point of time. The CD4 T cell joint fluid repertoire contained fewer and smaller oligoclonal expansions also largely restricted to the joint, suggesting that CD4 T cells participate perhaps by interacting cognitively to generate the CD8 clones. The inferred amino acid sequence of a single CD8 oligoclonal expansion revealed that they usually are composed of one or a few structurally related clones at the amino acid sequence level with beta-chains that encode identical or highly homologous CDR3 motifs. These were not shared among patients. Moreover, several clones that encoded the same amino acid sequence were found to be structurally distinct at the nucleotide level, strongly implying clonal selection and expansion is operating at the level of specific TCR-peptide interactions. The findings support a model of psoriatic arthritis inflammation involving extensive and selective Ag, likely autoantigen, driven intra-articular CD4, and CD8 T cell clonal expansions.

Convergence test for inversion of frequency-resolved optical gating spectrograms

We describe a new and simple method to aid in the analysis of retrieved pulses from inverted frequency-resolved optical gating (FROG) traces. The analysis can separate noise from distortion and shows that distortion is more deleterious to the retrieved pulse than is pure noise. The analysis relies on the fact that FROG traces can be constructed from a single outer product of two vectors, whereas distortion and noise require the sum of a series of outer products.

A model of the quaternary structure of the Escherichia coli F1 ATPase from X-ray solution scattering and evidence for structural changes in the delta subunit during ATP hydrolysis

The shape and subunit arrangement of the Escherichia coli F1 ATPase (ECF1 ATPase) was investigated by synchrotron radiation x-ray solution scattering. The radius of gyration and the maximum dimension of the enzyme complex are 4.61 +/- 0.03 nm and 15.5 +/- 0.05 nm, respectively. The shape of the complex was determined ab initio from the scattering data at a resolution of 3 nm, which allowed unequivocal identification of the volume occupied by the alpha3beta3 subassembly and further positioning of the atomic models of the smaller subunits. The delta subunit was positioned near the bottom of the alpha3beta3 hexamer in a location consistent with a beta-delta disulfide formation in the mutant ECF1 ATPase, betaY331W:betaY381C:epsilonS108C, when MgADP is bound to the enzyme. The position and orientation of the epsilon subunit were found by interactively fitting the solution scattering data to maintain connection of the two-helix hairpin with the alpha3beta3 complex and binding of the beta-sandwich domain to the gamma subunit. Nucleotide-dependent changes of the delta subunit were investigated by stopped-flow fluorescence technique at 12 degrees C using N-[4-[7-(dimethylamino)-4-methyl]coumarin-3-yl]maleimide (CM) as a label. Fluorescence quenching monitored after addition of MgATP was rapid [k = 6.6 s-1] and then remained constant. Binding of MgADP and the noncleavable nucleotide analog AMP . PNP caused an initial fluorescent quenching followed by a slower decay back to the original level. This suggests that the delta subunit undergoes conformational changes and/or rearrangements in the ECF1 ATPase during ATP hydrolysis.

Kinetics of Na(+)-dependent conformational changes of rabbit kidney Na+,K(+)-ATPase

The kinetics of Na(+)-dependent partial reactions of the Na+,K(+)-ATPase from rabbit kidney were investigated via the stopped-flow technique, using the fluorescent labels N-(4-sulfobutyl)-4-(4-(p-(dipentylamino)phenyl)butadienyl)py ridinium inner salt (RH421) and 5-iodoacetamidofluorescein (5-IAF). When covalently labeled 5-IAF enzyme is mixed with ATP, the two labels give almost identical kinetic responses. Under the chosen experimental conditions two exponential time functions are necessary to fit the data. The dominant fast phase, 1/tau 1 approximately 155 s-1 for 5-IAF-labeled enzyme and 1/tau 1 approximately 200 s-1 for native enzyme (saturating [ATP] and [Na+], pH 7.4 and 24 degrees C), is attributed to phosphorylation of the enzyme and a subsequent conformational change (E1ATP(Na+)3-->E2P(Na+)3 + ADP). The smaller amplitude slow phase, 1/tau 2 = 30-45 s-1, is attributed to the relaxation of the dephosphorylation/rephosphorylation equilibrium in the absence of K+ ions (E2P<==>E2). The Na+ concentration dependence of 1/tau 1 showed half-saturation at a Na+ concentration of 6-8 mM, with positive cooperatively involved in the occupation of the Na+ binding sites. The apparent dissociation constant of the high-affinity ATP-binding site determined from the ATP concentration dependence of 1/tau 1 was 8.0 (+/- 0.7) microM. It was found that P3-1-(2-nitrophenyl)ethyl ATP, tripropylammonium salt (NPE-caged ATP), at concentrations in the hundreds of micromolar range, significantly decreases the value of 1/tau 1, observed. This, as well as the biexponential nature of the kinetic traces, can account for previously reported discrepancies in the rates of the reactions investigated.

Dephosphorylation kinetics of pig kidney Na+,K+-ATPase

The kinetics of K+-stimulated dephosphorylation of the Na+,K+-ATPase were investigated at pH 7.4, 24 degrees C, and an ATP concentration of 1.0 mM via the stopped-flow technique using the fluorescent label RH421. Two different mixing procedures were used: (a) premixing with ATP to allow phosphorylation to go to completion, followed by mixing with KCl; and (b) simultaneous mixing with ATP and KCl. Using mixing procedure (a), the dephosphorylation rate constant of enzyme complexed with K+ ions could be determined directly to be </=366 s-1 and the rate constant for spontaneous dephosphorylation (without K+) </=60 s-1. The K+ concentration dependence of the observed reciprocal time constant showed half-saturation at a K+ concentration of 2.4-2.6 mM with positive cooperativity involved in the occupation of the K+ binding sites on the E2P conformation of the enzyme. Using mixing procedure (b), it was found that at saturating K+ concentrations the dephosphorylation of the enzyme is rate-limited by its phosphorylation, which occurs with a rate constant of approximately 190 s-1 (1). These results show that all reactions occurring after phosphorylation and prior to dephosphorylation, i.e., the E1P to E2P conformational transition as well as Na+ release and K+ binding steps, must be fast (>190 s-1).

Stopped-flow kinetic investigations of conformational changes of pig kidney Na+,K+-ATPase

The kinetics of Na+-dependent partial reactions of the Na+,K+-ATPase were investigated via the stopped-flow technique using the fluorescent labels RH421 and BIPM. After the enzyme is mixed with MgATP, both labels give almost identical kinetic responses. Under the chosen experimental conditions two exponential time functions are necessary to fit the data. The dominant fast phase, 1/tau1 approximately 180 s-1 (saturating [ATP] and [Na+], pH 7.4 and 24 degrees C), is attributed to phosphorylation of the enzyme and a subsequent conformational change (E1ATP(Na+)3 --> E2P(Na+)3 + ADP). The rate of the phosphorylation reaction measured by the acid quenched-flow technique was 190 s-1 at 100 microM ATP, suggesting that phosphorylation controls the kinetics of the RH421 signal and that the conformational change is very fast (>/=600 s-1). The rate of the RH421 signal was optimal at pH 7.5. The Na+ concentration dependence of 1/tau1 showed half-saturation at a Na+ concentration of 8-10 mM with positive cooperativity involved in the occupation of the Na+ binding sites. The apparent dissociation constant of the high affinity ATP binding site determined from the ATP concentration dependence of 1/tau1 was 7.0 (+/-0.6) microM, while the apparent Kd for the low affinity site and the rate constant for the E2 to E1 conformational change evaluated in the absence of Mg2+ were 143 (+/-17) microM and </= 28 s-1. At RH421 concentrations in the micromolar range, a decrease in the value of 1/tau1 is observed. On the basis of rapid quenched-flow measurements, this inhibition can be attributed to a reaction step subsequent to phosphorylation. This accounts for previously observed kinetic discrepancies between RH421 and BIPM.

A dynamic test of lower extremity function following anterior cruciate ligament reconstruction and rehabilitation

It is essential to assess the functional status of patients with surgically reconstructed and rehabilitated anterior cruciate ligaments prior to discharge. This study established a testing paradigm for functional force production and absorption. Data were obtained from 100 healthy subjects for maximal hops, controlled leaps, and hopping and leaping symmetry. Only 10% of symptomatic patients met maximal hopping criteria, while 15% achieved controlled leaping norms. Ninety-five percent of these patients failed to reach both hopping and leaping symmetry norms. Asymptomatic patients were 63% successful in meeting hopping criteria, and 57% were successful in meeting leaping criteria. Hop symmetry and leap symmetry were achieved at rates of 70% and 60%, respectively. The performance of both groups fell significantly below that of normal subjects (p < .05). Data suggest that this protocol does accurately assess functional and dysfunctional knees, and that force absorption may be more critical than force production in the determination of functional capacity.

Optical detection of membrane dipole potential: avoidance of fluidity and dye-induced effects

Fluorescent styrylpyridinium dyes have recently been suggested as probes of the membrane dipole potential and of the kinetics of electrogenic ion pumps. It is necessary, however, to be able to confidently attribute observed fluorescence changes to electrical effects alone and avoid interference from changes in membrane fluidity. Furthermore, the effect of the dyes themselves on the dipole potential must be investigated. The effect of membrane fluidity on the fluorescence excitation and emission spectra of the dyes RH421 and di-8-ANEPPS have been investigated in lipid vesicles by temperature scans between 15 and 60 degrees C. Both dyes show significant temperature-dependent shifts of their excitation spectra, the magnitude of which depend on the emission wavelength and on the lipid structure. In order to eliminate membrane fluidity effects, fluorescence must be detected at the red edge of the emission spectrum; in this case 670 nm. In order to avoid dye-induced shifts of the excitation spectra of membrane-bound dye, an excess molar ratio of lipid to dye of at least 200-fold is necessary. Fluorescence ratio measurements indicate qualitatively that dimyristoylphosphatidylcholine has a significantly higher dipole potential than that of dioleoylphosphatidylcholine.

Shift of the cellular oxidation-reduction potential in neural cells expressing Bcl-2

Expression of the protooncogene bcl-2 inhibits both apoptotic and in some cases necrotic cell death in many cell types, including neural cells, and in response to a wide variety of inducers. The mechanism by which the Bcl-2 protein acts to prevent cell death remains elusive. One mechanism by which Bcl-2 has been proposed to act is by decreasing the net cellular generation of reactive oxygen species. To evaluate this proposal, we measured activities of antioxidant enzymes as well as levels of glutathione and pyridine nucleotides in control and bcl-2 transfectants in two different neural cell lines-rat pheochromocytoma PC12 and the hypothalamic GnRH cell line GT1-7. Both neural cell lines overexpressing bcl-2 had elevated total glutathione levels when compared with control transfectants. The ratios of oxidized glutathione to total glutathione in PC12 and GT1-7 cells overexpressing bcl-2 were significantly reduced. In addition, the NAD+/NADH ratio of bcl-2-expressing PC12 and GT1-7 cells was two- to threefold less than that of control cell lines. GT1-7 cells overexpressing bcl-2 had the same level of glutathione peroxidase, catalase, superoxide dismutase, and glutathione reductase activities as control cells. PC12 cells overexpressing bcl-2 had a twofold increase in superoxide dismutase and catalase activity when compared with matched control transfected cells. The levels of glutathione peroxidase and glutathione reductase in PC12 cells overexpressing bcl-2 were similar to those of control cells. These results indicate that the overexpression of bcl-2 shifts the cellular redox potential to a more reduced state, without consistently affecting the major cellular antioxidant enzymes.

Neuregulins with an Ig-like domain are essential for mouse myocardial and neuronal development

Neuregulins are ligands for the erbB family of receptor tyrosine kinases and mediate growth and differentiation of neural crest, muscle, breast cancer, and Schwann cells. Neuregulins contain an epidermal growth factor-like domain located C-terminally to either an Ig-like domain or a cysteine-rich domain specific to the sensory and motor neuron-derived isoform. Here it is shown that elimination of the Ig-like domain-containing neuregulins by homologous recombination results in embryonic lethality associated with a deficiency of ventricular myocardial trabeculation and impairment of cranial ganglion development. The erbB receptors are expressed in myocardial cells and presumably mediate the neuregulin signal originating from endocardial cells. The trigeminal ganglion is reduced in size and lacks projections toward the brain stem and mandible. We conclude that IgL-domain-containing neuregulins play a major role in cardiac and neuronal development.

Expression of bcl-2 inhibits cellular radical generation

Bcl-2 expression in neural cells has been shown to inhibit apoptotic death in association with a decrease in reactive oxygen species. We present the results of a study that used electron spin resonance (ESR) measurements to evaluate the level of hydroxyl radical production in bcl-2 expressing GT1-7 cells and control cells. Incubation of cell monolayers with the spin trap N-t-alpha-phenylnitrone (PBN), and measurements of the hydroxyl radical production at different timepoints, revealed a higher radical production in control cells than in bcl-2 expressing cells, even in the absence of insult. The ESR signal was suppressed by addition of ethanol, indicating that the trapped radical was indeed hydroxyl radical. The mechanism by which the expression of bcl-2 leads to a decrease in cellular production of hydroxyl radical is unknown.

Parental needs following the discharge of a hospitalized child

Many studies have addressed parents' needs when their child is hospitalized, yet few studies have identified the needs of parents after their child is discharged. An exploratory-descriptive study of families (N = 16) at a large acute care general hospital in Canada examined parents' needs following their child's discharge and parents' perceptions of the effectiveness of a discharge follow-up program. Parents described needs in two areas: (a) the need for detailed information about their child, and (b) the need for support regarding multiple stresses that their families were facing. Parents reported high levels of satisfaction with the discharge follow-up program, and all of the families recommended its continuance.

Quantitative species measurements in microgravity flames with near-IR diode lasers

Absolute concentrations of water vapor are measured in microgravity (µ-g), nonpremixed methane, and propane jet flames with diode-laser wavelength modulation spectroscopy. These experiments are performed in the 2.2-s µ-g drop facility at the NASA Lewis Research Center. Abel inversion methods are used to determine time-dependent radial profiles from eight line-of-sight projections across the flames. At all measured heights above the nozzle, water vapor spatial distributions in µ-g flames are much wider than their 1-g counterparts. Radial growth of the water signal continues throughout the drop, verifying earlier suggestions that a steady state is not reached during the duration of the test, despite a quasi-steady flame shape. Large amounts of water vapor are observed at larger radii, at odds with visual (video) observations and numerical predictions.

Expression of bcl-2 inhibits necrotic neural cell death

Cell death has been described as either apoptotic, in which the cell actively participates, or necrotic, in which the cell is felt to be passive. The proto-oncogene bcl-2 has been shown to inhibit apoptosis in some hematopoietic and neural cells, by an unknown mechanism. We demonstrate that bcl-2 inhibits the necrosis of neural cells induced by glutathione depletion. This finding demonstrates that bcl-2 does not inhibit the cellular death program directly; rather, bcl-2 modulates a cellular process that leads to apoptosis under some conditions but necrosis under others.

Neural transplantation of cells expressing the anti-apoptotic gene bcl-2

Long-term survival of grafted neural cells is a major goal of neural transplantation, but typical survival rates of grafted fetal neurons are in the range of 5-10%. Whether the death of transplanted neural cells is apoptotic or necrotic is unknown. The expression of the proto-oncogene bcl-2 inhibits both apoptotic and necrotic neural cell death. In a 6-OHDA induced rat model of Parkinson's disease, Hoechst 33258 prelabelled conditionally immortalized nigral cells engineered to express bcl-2 were stereotactically transplanted into the striatum ipsilaterally to the lesioned nigrostriatal pathway. Sixteen rats received bcl-2 transfected cells, 15 received cells transfected with vector alone, and 12 received either a nondopaminergic cell line or were sham transplanted as controls. Four wk following transplantation, the rats with grafts containing bcl-2 expressing cells showed an approximately 43% decrease in apomorphine-induced rotational behavior. In contrast, 12% improvement occurred in the rats with transplanted cells transfected with vector alone (p < 0.05), and no improvement occurred in sham-operated animals (p < 0.05). Histological examination showed no tumor formation. Despite the difference in behavioral effect, no clear difference in Hoechst fluorescent staining or staining for TH, GFAP was noted; therefore, it is unknown at present whether the observed effect was due to a difference in survival or to increased efficacy per surviving transplanted neural cell, or both.

Single-shot measurement of the amplitude and phase of ultrashort laser pulses in the violet

Using single-shot, self-diffraction, frequency-resolved optical gating, we measure the complete electric field amplitude and phase of 405-nm second-harmonic pulses from an amplified Ti:sapphire system. The single-shot frequency-resolved optical gating device gives both qualitative and quantitative information, which is useful for analyzing and optimizing the grating compressor in the chirped-pulse amplification system.

bcl-2 expression decreases methyl mercury-induced free-radical generation and cell killing in a neural cell line

Methyl mercury neurotoxicity is associated with a broad range of neuropathologic and biochemical disturbances which include induction of oxidative injury. Treatment of the hypothalamic neural cell line GT1-7 with 10 microM methyl mercury (MeHg) for 3 h resulted in increased formation of reactive oxygen species (ROS), and decreased levels of reduced glutathione (GSH), associated with 20% cell death. Cells transfected with an expression construct for the anti-apoptotic proto-oncogene, bcl-2, displayed attenuated ROS induction and negligible cell death. Twenty-four-h exposure to 5 microM MeHg killed 56% of control cells, but only 19% of bcl-2-transfected cells. By using diethyl maleate to deplete cells of GSH, we demonstrate that the differential sensitivity to MeHg was not due solely to intrinsically different GSH levels. The data suggest that MeHg-mediated cell killing correlates more closely with ROS generation than with GSH levels and that bcl-2 protects MeHg-treated cells by suppressing ROS generation.

Single-shot measurement of the intensity and phase of a femtosecond UV laser pulse with frequency-resolved optical gating

We extend to the ultraviolet frequency-resolved optical gating a new method for measuring the intensity and phase evolution of an individual ultrashort pulse without assumption. Using frequency-resolved optical gating, we measure a 310-fs, 308-nm pulse, whose phase is approximately cubic in time. We show that this phase distortion probably results from self-phase modulation and amplifier detuning.

Neural-targeted gene therapy for rodent and primate hemiparkinsonism

Expression of the rate-limiting enzyme for catecholamine biosynthesis, tyrosine hydroxylase (TH), via retroviral and plasmid expression vectors improved the efficacy of conditionally immortalized nigral neural cells in ameliorating rodent and nonhuman primate models of Parkinson's disease through neural transplantation. No improvement in rotational behavior occurred when sham transplants or nondopaminergic transplants were performed. Transplantation of the temperature-sensitive immortalized parental nigral neural line with a TH expression vector resulted in improvement for at least 2 months. Improvement was accompanied by HPLC evidence of increased L-DOPA production and immunocytochemical evidence of TH in the transfected cells increased over that of the parental line. No tumor formation was detected. These results suggest that: (1) temperature-sensitive immortalized neural cells may be genetically engineered successfully to improve their efficacy for the treatment of parkinsonism; and (2) a change in L-DOPA production, as opposed to growth factor production or other factors, is likely to account for the observed improvement, since the parental and derived lines differ by a single gene.

Bcl-2 inhibition of neural death: decreased generation of reactive oxygen species

The proto-oncogene bcl-2 inhibits apoptotic and necrotic neural cell death. Expression of Bcl-2 in the GT1-7 neural cell line prevented death as a result of glutathione depletion. Intracellular reactive oxygen species and lipid peroxides rose rapidly in control cells depleted of glutathione, whereas cells expressing Bcl-2 displayed a blunted increase and complete survival. Modulation of the increase in reactive oxygen species influenced the degree of cell death. Yeast mutants null for superoxide dismutase were partially rescued by expression of Bcl-2. Thus, Bcl-2 prevents cell death by decreasing the net cellular generation of reactive oxygen species.

BCL-2 blocks glutamate toxicity in neural cell lines

Glutamate has been shown, at high concentrations (5-10 mM), to lead to death in cells of the pheochromocytoma cell line PC12. We report that similar concentrations of glutamate also kill immortalized central neural cell lines, and that the expression of the proto-oncogene bcl-2 in these cell lines blocks glutamate neurotoxicity. Potassium chloride (25 mM) also protects a cerebellar neuronal cell line, but not PC12 cells, from glutamate toxicity.

Single-shot measurement of the intensity and phase of an arbitrary ultrashort pulse by using frequency-resolved optical gating

We introduce a new technique, frequency-resolved optical gating, for measuring the intensity I(t) and the phase ø(t) of an individual arbitrary ultrashort pulse. Using an instantaneous nonlinear-optical interaction of two variably delayed replicas of the pulse, frequency-resolved optical gating involves measuring the spectrum of the signal pulse versus relative delay. The resulting trace, a spectrogram, yields an intuitive full-information display of the pulse. Inversion of this trace to obtain the pulse intensity and phase is equivalent to the well-known two-dimensional phase-retrieval problem and thus yields essentially unambiguous results for I(t) and ø(t).

bcl-2 inhibits death of central neural cells induced by multiple agents

The protooncogene bcl-2, which has been implicated in B-cell lymphoma development, inhibits apoptosis due to growth factor withdrawal in some, but not all, hematopoietic cells. Recently we found that bcl-2 also inhibits apoptosis in PC12 pheochromocytoma cells. We now report that bcl-2 inhibits the death of a central neural cell line due to serum and growth factor withdrawal, the calcium ionophore A23187, glucose withdrawal, membrane peroxidation, and, in some cases, free radical-induced damage. This broad range of protective effects of BCL-2 protein suggests that BCL-2 may interact with a central step in neural cell death. Measurements of intracellular free calcium suggest that BCL-2 alters the transduction of neural death signals at a point distal to the rise in intracellular free calcium.