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Biomedical subjects

B L Roberts

Publications and source records attributed to B L Roberts.

At least 19 recordsLinked to original sources
PubMed2006

Exercise enhances axonal growth and functional recovery in the regenerating spinal cord.

We investigated whether enhancing locomotory activity could accelerate the axonal growth underlying the significant recovery of function after a complete spinal transection in the eel, Anguilla. Eels with low spinal transections (at about 60% body length) were kept in holding tanks, where they were inactive, or made to swim continually against a water current at about one body length/s. Their locomotion was periodically assessed by measuring tail beat frequencies at different swimming speeds. Axonal growth was determined from anterograde labeling with 1,1'-diotadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate, inserted postmortem into the spinal cord, just rostral to the transection. Twenty days after surgery, there were significantly more labeled growth cones more than 2 mm caudal from the transection in the exercised fish (74.6+/-2.3%; cf. 34.5+/-1.1%). This difference was still observed at 40 days (57.9+/-1.6% cf. 42.1+/-2% >2 mm), but the regenerated axons were of similar maximum lengths by 120 days (9.8+/-0.3 cf. 7.7+/-2.8 mm). After surgery, each eel undulated its whole body faster at any given swimming speed, thus changing the linear relationship between tail beat frequency and forward speed established before transection. The slope increased by up to 112.5+/-27.4% over the first 8 days post-surgery in inactive animals, while a smaller rise (45.6+/-10.5%) was observed in exercised fish during this period. Thereafter, the slope progressively declined to pre-surgery levels in both groups of animals, but the recovery occurred within 20+/-4 days in exercised eels, as opposed to 40+/-5 days in inactive fish. The locomotory performance of sham-operated fish was unaffected by 10 days of continual locomotion and remained similar to that of naïve eels, pre-transection. These data show that elevated locomotory activity enhances axonal growth and accelerates recovery of locomotory function.

Anguilla↗
PubMed2006

Effects of teaching resourcefulness skills to elders.

The objective of this study was to examine the effects of learned resourcefulness training (LRT) on health of elders in retirement communities (RCs). In a clinical trial, 46 elders in four randomly selected RCs received resourcefulness training and were compared to 43 elders in four RCs who participated in a focused reflection reminiscence (FRR) group. The two groups were similar at baseline. Repeated measures analysis of variance revealed no changes on anxiety or depression over time; however, both were significantly correlated with functional status (r's = 0.29 and 0.35, p's < 0.01), self-assessed health (r's = -0.18 and -0.26, p's < 0.05), and resourcefulness (r's = -0.24 and -0.21, p's < 0.05). Although main effects for group were not significant, interaction effects of group and time on self-assessed health and functional status were found. These findings suggest that although teaching resourcefulness to groups of elders in RCs may have beneficial effects on improving their perception of health and functioning over time, significant effects on mental health may not be apparent.

Activities of Daily Living↗
PubMed2004

New method of measuring electric dipole moments in storage rings.

A new highly sensitive method of looking for electric dipole moments of charged particles in storage rings is described. The major systematic errors inherent in the method are addressed and ways to minimize them are suggested. It seems possible to measure the muon EDM to levels that test speculative theories beyond the standard model.

Journal Article↗
PubMed2004

Measurement of the negative muon anomalous magnetic moment to 0.7 ppm.

The anomalous magnetic moment of the negative muon has been measured to a precision of 0.7 ppm (ppm) at the Brookhaven Alternating Gradient Synchrotron. This result is based on data collected in 2001, and is over an order of magnitude more precise than the previous measurement for the negative muon. The result a(mu(-))=11 659 214(8)(3) x 10(-10) (0.7 ppm), where the first uncertainty is statistical and the second is systematic, is consistent with previous measurements of the anomaly for the positive and the negative muon. The average of the measurements of the muon anomaly is a(mu)(exp)=11 659 208(6) x 10(-10) (0.5 ppm).

Journal Article↗
PubMed2004

Functional recovery and axonal growth following spinal cord transection is accelerated by sustained L-DOPA administration.

The eel, Anguilla anguilla, as with other fish species, recovers well from spinal cord injury. We assessed the quality of locomotion of spinally transected eels from measurements made from video recordings of individuals swimming at different speeds in a water tunnel. Following transection of the spinal cord just caudal to the anus, the animals displayed higher tail beat frequencies and lower tail beat amplitudes than before surgery, owing to the loss of power in this region. Swimming performance then progressively recovered, appearing normal within 1 month of surgery. Eels with similar transections, but given regular, repeated intraperitoneal injections (50 mg/kg) of l-3,4-dihydroxyphenylalanine (L-DOPA) showed an equivalent pattern of decline and recovery that was 10-20 days shorter than that seen in non-treated fish. Axonal growth into the denervated cord, as determined from anterograde labelling experiments, was also more rapid in the drug-treated fish. L-DOPA treatment increased the activity of all fish for up to 18 h, and accelerated the spontaneous movements ('spinal swimming') made by the denervated, caudal portion of the animal that appeared following transection. We suggest that this enhancement of locomotion underlies the accelerated axonal growth and, hence, functional recovery.

Anguilla↗
PubMed2003

Long-term outcomes following percutaneous tracheostomy using the Griggs technique.

Percutaneous tracheostomy is commonly performed in the intensive care unit. This study assesses the long-term outcomes following percutaneous tracheostomy using the Griggs technique. We carried out a prospective observational cohort study. Two hundred and eight patients who had undergone percutaneous tracheostomy between 1 September 1996 and 31 July 2000 and who were alive at least six months following the procedure, were included in the study. Median follow-up was at 30 months. All patients were sent questionnaires regarding relevant symptoms. One hundred and six (51%) responded and were invited for further follow-up. Forty-three (20.6%) patients underwent scar evaluation by the investigators and 41/208 (19.7%) underwent spirometry. Of the responders, 38% complained of some degree of voice change and 12% complained of ongoing severe cough. Thirty-one per cent complained of shortness of breath, with more than half of these having concomitant heart or lung disease, which may explain this. Eighty-one per cent of patients had minimally visible or a visible but neat scar. Eight patients (8/41 (19.5%)) had some evidence of upper airway obstruction on spirometry, but only 2/41 (5% of patients) were symptomatic (stridor or shortness of breath). We conclude that percutaneous tracheostomy using the Griggs technique has an acceptable long-term complication rate.

Adolescent↗
PubMed2002

Measurement of the positive muon anomalous magnetic moment to 0.7 ppm.

A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).

Journal Article↗
PubMed2002

Cerebellar regulation of sensorimotor activity in brown trout.

Evoked field potentials were recorded from the mesencephalic ('optic') tectum, cerebellar corpus, midline rhombencephalon, and spinal cord of decerebrated brown trout in response to single electrical shocks given to an optic nerve. Evoked responses were also recorded from the rhombencephalon and spinal cord following stimulation (singly and with trains) to the optic tectum and to the cerebellar corpus. The potentials recorded from the tectum in response to optic nerve stimulation were similar in form to those reported by other workers from other species of teleost. The rhombencephalic responses to optic nerve and tectal stimulation were complex and comprised presumed pre- and post-synaptic events. Cerebellar stimulation evoked no detectable responses in these brain regions, but when given prior to tectal stimulation (by up to 10 ms), tectally-evoked spinal cord responses were reduced in amplitude by as much as 85%. After cerebellar ablation, there was no difference from controls in the latency, form or amplitude of any response, even when tested with paired pulse stimulation. However, when the cerebellum was ablated, rhombencephalic and spinal responses to optic nerve and tectal stimulation were markedly enhanced (by 200-300%). These clear-cut complimentary consequences of cerebellar ablation or stimulation emphasize the gain-setting role of the cerebellum and indicate, at least in relation to optically evoked motor activity, that cerebellar regulation acts at the level of the supraspinal drive to spinal motor circuits and not within the sensory centers.

Animals↗
PubMed2002

The effects of inhalation of a novel nitric oxide donor, DETA/NO, in a patient with severe hypoxaemia due to acute respiratory distress syndrome.

Aerosolized NONOates have been investigated in animal models in acute pulmonary hypertension, but none have been used in humans. We report the first use of aerosolized diethylenetriamine nitric oxide adduct (DETA/NO), a NONOate, in a patient with severe acute respiratory distress syndrome. Both pulmonary vascular resistance index and mean pulmonary arterial pressure were reduced by a mean of 26% and 18% respectively after the administration of a single dose of DETA/NO (150 micromol). Intrapulmonary shunting also improved. There were no significant changes in systemic arterial pressure or arterial methaemoglobin concentration after DETA/NO inhalation. We conclude that DETA/NO aerosol produced selective pulmonary vasodilation, with an improvement in pulmonary haemodynamics and oxygenation, while having no measurable effect on the systemic circulation.

Administration, Inhalation↗
PubMed2001

Fos-like immunohistochemical identification of neurons active during the startle response of the rainbow trout.

Activity-dependent Fos-like expression was investigated immunohistochemically in rainbow trout (Oncorhynchus mykiss) that had performed vibratory-evoked startle responses. We found significantly higher numbers of Fos-like-immunoreactive neurons in the reticular formation, in the octavolateral area, and in several cranial nerve motor nuclei in the brain and in the motor column of the spinal cord of startled fish than in control fish. In one fish, in which stimulation did not evoke startle responses, substantial numbers of positive cells occurred in the brain, primarily in the magnocellular octavolateral nucleus. We observed Fos-like-immunoreactive neurons in cell groups that are known to participate in the startle response (e.g., the Mauthner cell) as well as in cell groups that have been proposed but until now not shown to be involved.

Animals↗
PubMed2001

Precise measurement of the positive muon anomalous magnetic moment.

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Journal Article↗
PubMed2001

Changing synaptic connections on cell bodies of growing identified spinal motoneurons of the eel, Anguilla.

As the target musculature they innervate grows throughout life, certain segmental motoneurons from the spinal cord of Anguilla, readily identified on the basis of their form and position, also increase in size. In doing so, they present a steadily increasing target to the spinal and supraspinal neurons that innervate them. How the afferent neurons respond was assessed by measuring features of their synaptic boutons contacting the motoneuronal perikarya, as seen with electron microscopy. About 60% of the perimeter of the perikaryal profile of each motoneuron was found to be covered with synaptic bouton profiles, a value that is independent of the size of the motoneuron. Furthermore, the distances between synaptic profiles, their contact sizes (measured as apposition length) and the number and size of the vesicles each profile contains were all found to be relatively constant and also independent of motoneuronal size. In contrast, the number of synaptic profiles contacting a motoneuron correlated well with its perikaryal size. Our findings indicate that the challenge of a growing neuronal target is met by a steady increase in the number of contacting boutons, the form and spacing of which are held relatively constant; this strategy will require continual synaptic realignment at the target.

Anguilla↗
PubMed2001

Recovery of locomotion correlated with axonal regeneration after a complete spinal transection in the eel.

This research has examined the relationship between axonal regeneration and the return of normal movement following complete transection of the spinal cord. We made measurements of tail beat frequency and amplitude of the caudal body wave from video recordings of eels (Anguilla anguilla) swimming in a water tunnel at several speeds. Each eel was then anaesthetised and the spinal cord cut caudal to the anus; in some animals the resulting gap was filled with a rubber block. All animals were kept at 25 degrees C for recovery periods ranging from 7 to 128 days, during which their swimming performance was monitored regularly. Each fish was then re-anaesthetised and perfused with fixative and the regrowing descending axons labelled with 1,1'-diotadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate. For all animals and at all speeds after surgery, tail beat frequency increased, while amplitude decreased. In non-blocked animals, an improvement in performance was first seen from 8 days following transection and thereafter tail beat frequency decreased progressively until it had returned to normal after 35 to 45 days, while amplitude remained below baseline until at least 45 days. In these animals, few axonal growth cones had penetrated the caudal stump by 7 days, but some had extended as much as 3 mm by 15 days. Many had reached as far as 6 mm between 25 and 36 days, while by 128 days they had progressed up to 10.5 mm. Contralateral crossing was never observed. Functional recovery was never witnessed in animals in which the cord had been blocked and these eels swam at all times with elevated tail beat frequency and reduced caudal amplitude. No labelled axons could be traced into the caudal spinal cord at any recovery stage in such animals. We conclude that re-innervation of only 1-2 segments caudal to the injury is necessary for functional recovery, although continued axonal growth may be important for the refinement of some aspects of movement.

Anguilla↗
PubMed2001

Mechanisms of cell death induced by suicide genes encoding purine nucleoside phosphorylase and thymidine kinase in human hepatocellular carcinoma cells in vitro.

For gene therapy of hepatocellular carcinoma (HCC), the Escherichia coli purine nucleoside phosphorylase (PNP)/fludarabine suicide gene system may be more useful than the herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system as a result of a stronger bystander effect. To analyze the molecular mechanisms involved in PNP/fludarabine-mediated cell death in human HCC cells in comparison with HSV-tk/GCV, we transduced human HCC cells of the cell lines, HepG2 and Hep3B, with PNP or HSV-tk using adenoviral vectors, followed by prodrug incubation. Both systems predominantly induced apoptosis in HepG2 and Hep3B cells. PNP/fludarabine induced strong p53 accumulation and a more rapid onset of apoptosis in p53-positive HepG2 cells as compared with p53-negative Hep3B cells, but efficiency of tumor cell killing was similar in both cell lines. In contrast, HSV-tk/GCV-induced apoptosis was reduced in p53-negative Hep3B cells as compared with p53-positive HepG2 cells. HSV-tk/GCV, but not PNP/fludarabine, caused up-regulation of Fas in p53-positive HepG2 cells and of Fas ligand (FasL) in both HCC cell lines. These results demonstrate cell line-specific differences in response to treatment with PNP/fludarabine and HSV-tk/GCV, respectively, and indicate that PNP/fludarabine may be superior to HSV-tk/GCV for the treatment of human HCC because of its independence from p53 and the Fas/FasL system.

Apoptosis↗
PubMed2001

The relationships of brain stem systems to their targets in the spinal cord of the eel, Anguilla anguilla.

We have investigated the detail with which supraspinal neurons innervate different regions in the spinal cord. Horseradish peroxidase was applied at different levels of the cord: (1) to the cut surface; (2) injected iontophoretically into one side; or (3) into one of the motoneuron pools innervating different muscle compartments. In all cases, labeled neurons were found throughout the brain distributed over nuclear groups identified in previous fish studies. Some cells from all but one of the nuclei have axons that extend over the whole length of the cord and about 50% of all neurons project to post-anal levels. No topographical distribution relating somal position and target location was found. Sixty seven percent of the neurons send axons to the ipsilateral side of the cord, although most nuclear groups provide a bilateral projection. Nucleus ruber projects entirely contralaterally. The descending and magnocellular octavolateral nuclei, and the descending nucleus of the trigeminal nerve project entirely ipsilaterally. Neurons that project to the spinal motoneuron pools innervating the myotomal red- or white-muscle are distributed throughout the same brain stem nuclei, but the cell bodies of those neurons innervating white-muscle motoneurons are larger. Nineteen pairs of cells were found to be consistently identifiable and all project to all levels of the cord; they were only labeled from injections made into the white-muscle motoneuron pool.

Anguilla↗
PubMed2000

Strategy for monitoring T cell responses to NY-ESO-1 in patients with any HLA class I allele.

NY-ESO-1 elicits frequent antibody responses in cancer patients, accompanied by strong CD8(+) T cell responses against HLA-A2-restricted epitopes. To broaden the range of cancer patients who can be assessed for immunity to NY-ESO-1, a general method was devised to detect T cell reactivity independent of prior characterization of epitopes. A recombinant adenoviral vector encoding the full cDNA sequence of NY-ESO-1 was used to transduce CD8-depleted peripheral blood lymphocytes as antigen-presenting cells. These modified antigen-presenting cells were then used to restimulate memory effector cells against NY-ESO-1 from the peripheral blood of cancer patients. Specific CD8(+) T cells thus sensitized were assayed on autologous B cell targets infected with a recombinant vaccinia virus encoding NY-ESO-1. Strong polyclonal responses were observed against NY-ESO-1 in antibody-positive patients, regardless of their HLA profile. Because the vectors do not cross-react immunologically, only responses to NY-ESO-1 were detected. The approach described here allows monitoring of CD8(+) T cell responses to NY-ESO-1 in the context of various HLA alleles and has led to the definition of NY-ESO-1 peptides presented by HLA-Cw3 and HLA-Cw6 molecules.

Alleles↗
PubMed2000

HLA-A2.1/K(b) transgenic murine dendritic cells transduced with an adenovirus encoding human gp100 process the same A2.1-restricted peptide epitopes as human antigen-presenting cells and elicit A2.1-restricted peptide-specific CTL.

HLA-A2.1/K(b) transgenic mice (A2.1/K(b) mice) were used to investigate the processing of human gp100 melanoma antigen by murine antigen presenting cells (APC). Bone marrow-derived dendritic cells (DC) from A2.1/K(b) mice were transduced with adenovirus encoding human gp100 (Ad2/hugp100v2). The Ad2/hugp100v2-transduced DC express human gp100, as documented by immunoperoxidase staining. Flow cytometric analysis demonstrates that Ad vector transduction does not downregulate expression of several markers, including MHC class I. We show that Ad2/hugp100v2-transduced DC are recognized by peptide-specific, A2.1-restricted CTL, suggesting correct processing and presentation of the hugp100 antigen by murine DC. To assess dominance among the various A2.1-restricted epitopes encoded by hugp100, A2.1/K(b) transgenic mice were immunized with Ad2/hugp100v2-transduced DC. Resulting effector cytotoxic T lymphocytes (CTL) were assayed for peptide specificity using a panel of six synthetic peptides known to encode A2.1-restricted epitopes of human gp100 (denoted G154, G177, G209, G280, G457, G476). CTL obtained from Ad2/hugp100v2-transduced DC immunized A2.1/K(b) mouse lysed target cells presenting five of the six epitopes, supporting the observation that murine cells correctly process the hugp100 antigen. The immunogenicity of individual gp100 epitopes correlates with their binding affinity to A2.1. CTL generated from A2.1/K(b) mice immunized with Ad2/hugp100v2-transduced DC also specifically recognize A2.1(+)/gp100(+) human melanoma cells. These data suggest that murine APC process and present the same set of HLA-restricted peptides, similar to human APC. HLA transgenic mice serve as a useful model system to study class I-restricted epitopes of human tumor-associated antigens.

Adenoviridae↗