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Biomedical subjects

James Russell

Publications and source records attributed to James Russell.

13 recordsLinked to original sources
PubMed2007

Detecting changes in tumor hypoxia with carbonic anhydrase IX and pimonidazole.

We have used immunohistochemistry to examine the dynamics of tumor hypoxia.. Expression of CAIX is known to be influenced by tumor hypoxia, and this protein has been shown to be an endogenous hypoxia marker in several models. However, due to its long half-life, it could also be present in oxygenated tissue that had recently been hypoxic. To investigate this issue we have compared CAIX expression to the exogenous hypoxia marker, pimonidazole using HT29 (human colorectal cancer) xenografts. We manipulated tumor hypoxia with carbogen and hydralazine, treatments that respectively increased and decreased tumor oxygenation. (Carbogen was given 75 minutes and hydralazine 30 minutes before sacrifice). In tumors from the control group, CAIX and pimonidazole exhibited similar (though not identical) spatial distribution, and for both markers, the fraction of the section staining positively was similar (13.2% and 12.6% respectively). The mice treated with hydralazine showed a significant increase in pimonidazole accumulation (37.2%, p = 0.03), though the CAIX positive fraction was unchanged (14.2%). In contrast, in the carbogen group pimonidazole staining decreased to 3% (p = 0.01) though CAIX expression was again unaltered. These results suggest that comparison of CAIX and pimonidazole will allow for the detection of reoxygenation.

Animals↗
PubMed2006

Lifestyle intervention for pre-diabetic neuropathy.

OBJECTIVE: The purpose of this study was to evaluate intraepidermal nerve fiber density (IENFD) as a sensitive measure of neuropathy change in patients with neuropathy associated with impaired glucose tolerance (IGT) receiving lifestyle intervention based on that used in the Diabetes Prevention Program. RESEARCH DESIGN AND METHODS: We performed 3-mm skin biopsies with measurement of IENFD at the distal leg and proximal thigh at baseline and after 1 year in 32 subjects with IGT. Each received individualized diet and exercise counseling as a standard of care. Nerve conduction studies, quantitative sensory testing, quantitative sudomotor axon reflex testing, and the Michigan Diabetic Neuropathy score were performed, and a visual analog pain scale was completed. Two-hour oral glucose tolerance tests (OGTTs) following the American Diabetes Association guidelines were performed, and serum lipid levels were measured at baseline and 1 year later. RESULTS: Baseline distal IENFD was 0.9 +/- 1.2 fibers/mm and proximal IENFD was 4.8 +/- 2.3 fibers/mm. Baseline distal IENFD correlated with fasting glucose (P < 0.001) and OGTT (P < 0.01). After 1 year of treatment, there was a 0.3 +/- 1.1-fiber/mm improvement in distal IENFD and a 1.4 +/- 2.3-fiber/mm improvement in proximal IENFD (P < 0.004). The change in proximal IENFD correlated with decreased neuropathic pain (P < 0.05) and a change in sural sensory amplitude (P < 0.03). CONCLUSIONS: These findings indicate that diet and exercise counseling for IGT results in cutaneous reinnervation and improved pain. Skin biopsy was the most sensitive measure of neuropathy change over 1 year. IENFD should be included as an end point in future neuropathy trials.

Aged↗
PubMed2005

Targeting hypoxia and angiogenesis through HIF-1alpha inhibition.

Hypoxia is an important phenomenon in the tumor microenvironment. Hypoxic tumors are more aggressive and resistant to anti-neoplastic treatments. HIF-1alpha plays a major role in the response of tumors to hypoxia, and it is mainly responsible for the "angiogenic switch". HIF-1alpha contributes to tumor aggressiveness, invasiveness, and resistance to radiotherapy and chemotherapy. Targeting HIF-1alpha is an attractive strategy, with the potential for disrupting multiple pathways crucial for tumor growth. We review recent findings on the potential efficacy of small molecules to downregulate HIF-1alpha. These promising drugs inhibit HIF-1alpha synthesis or transcriptional activity by blocking a variety of steps in several different signaling pathways. Blocking HIF-1alpha activity should not only downregulate tumor angiogenesis, but also interfere with glycolytic metabolism and tumor cell growth. This strategy could also improve the efficiency of established tumor therapies.

Cell Hypoxia↗
PubMed2005

Polyneuropathy with Impaired Glucose Tolerance: Implications for Diagnosis and Therapy.

Prediabetes is associated with a length-dependent polyneuropathy that typically is sensory predominant and painful. A diagnosis of prediabetes should be sought in patients with otherwise idiopathic sensory-predominant neuropathy by doing a 2-hour oral glucose tolerance test. Fasting plasma glucose of 100 to 125 mg/dL or 2-hour glucose 140 to 199 mg/dL (impaired glucose tolerance) constitutes prediabetes. Most patients with neuropathy associated with prediabetes (NAP) are obese and show metabolic manifestations of insulin resistance, including hyperlipidemia and hypertension. Appropriate treatment addresses hyperglycemia, insulin resistance, and neuropathic pain. Professionally administered individualized diet and exercise counseling (modeled on the Diabetes Prevention Program) has been shown to be more effective than glucose-lowering medications in preventing progression from impaired glucose tolerance to diabetes, and is the mainstay of treatment for all patients with NAP. The goals of this therapy should be a 5% to 7% reduction in weight and an increase to 30 minutes of moderate exercise five times weekly. Patients with prediabetes are at increased risk for myocardial infarction, stroke, and peripheral vascular disease. Therefore, risk reduction with control of hypertension and hyperlipidemia is essential. Neuropathic pain troubles nearly every patient with NAP, and often limits aerobic exercise. No trials have specifically addressed the patient population with NAP, and neuropathic pain treatment closely follows recommendations for diabetic neuropathy. Gabapentin, lamotrigine, and tricyclic antidepressants are well-validated first-line therapies. Adjunctive therapy with opioids, nonsteroidal anti-inflammatory drugs often are necessary. Diet and exercise seem to reduce neuropathic pain in patients with NAP.

Journal Article↗
PubMed2005

Justifying all the fuss about false belief.

The classic study by Wimmer and Perner showed that children below the age of about 4 years of age fail to appreciate others' false beliefs. This opened the floodgates to the theory-of-mind research programme. Recently, a study by Riggs and Simpson has called the central challenge of false belief into question, reporting similar difficulties with true belief. I would argue, however, that not only should the acquisition of false belief remain a central concern but that we should think harder about it and its earlier manifestations.

Child Development↗
PubMed2004

The ghost condition: imitation versus emulation in young children's observational learning.

Although observational learning by children may occur through imitating a modeler's actions, it can also occur through learning about an object's dynamic affordances--a process that M. Tomasello (1996) calls "emulation." The relative contributions of imitation and emulation within observational learning were examined in a study with 14- to 26-month-old children. The effectiveness of a "ghost" condition, in which the effective operation of the means apparatus was seen to occur without human agency, was compared with that of a standard modeling procedure in which the child saw an experimenter demonstrate the means action. The ghost condition was as likely to encourage observational learning as was the modeling condition; indeed, performance in the ghost condition was significantly better. The role of emulation in the development of observational learning is discussed in the context of a possible form of goal directedness without agency.

Attention↗
PubMed2003

Ca2+ influx-independent synaptic potentiation mediated by mitochondrial Na(+)-Ca2+ exchanger and protein kinase C.

Activity-dependent modulation of synaptic transmission is an essential mechanism underlying many brain functions. Here we report an unusual form of synaptic modulation that depends on Na+ influx and mitochondrial Na(+)-Ca2+ exchanger, but not on Ca2+ influx. In Ca(2+)-free medium, tetanic stimulation of Xenopus motoneurons induced a striking potentiation of transmitter release at neuromuscular synapses. Inhibition of either Na+ influx or the rise of Ca2+ concentrations ([Ca2+]i) at nerve terminals prevented the tetanus-induced synaptic potentiation (TISP). Blockade of Ca2+ release from mitochondrial Na(+)-Ca2+ exchanger, but not from ER Ca2+ stores, also inhibited TISP. Tetanic stimulation in Ca(2+)-free medium elicited an increase in [Ca2+]i, which was prevented by inhibition of Na+ influx or mitochondrial Ca2+ release. Inhibition of PKC blocked the TISP as well as mitochondrial Ca2+ release. These results reveal a novel form of synaptic plasticity and suggest a role of PKC in mitochondrial Ca2+ release during synaptic transmission.

Action Potentials↗
PubMed2003

Memory development in the second year: for events or locations?

We employed an object-placement/object-removal design, inspired by recent work on 'episodic-like' memory in scrub jays (Clayton, N. S., & Dickinson, A. (1998). Episodic-like memory during cache recovery by scrub jays. Nature, 395, 272-274), to examine the possibility that children in the second year of life have event-based memories. In one task, a successful search could have been due to the recall of an object-removal event. In the second task, a successful search could only have been caused by recall of where objects were located. Success was general in the oldest group of children (21-25 months), while performance was broadly similar on the two tasks. The parsimonious interpretation of this outcome is that the first task was performed by location memory, not by event memory. We place these data in the context of object permanence development.

Child Development↗
PubMed2002

Sequencing of production-scale synthetic oligonucleotides by enriching for coupling failures using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A technique for sequencing oligonucleotides using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is described. The series of coupling failure species are extracted from the dimethoxytrityl-on, full-length oligonucleotide in crude synthetic material using C18 stationary-phase cartridges. These concentrated failure species can be easily detected by MALDI-TOF, which determines the mass difference between spectral ions to identify a particular base. The solid-phase extraction step greatly enhances ion signals and mass resolution, and sequencing information is generally obtained from the 5' end up to the first three to four nucleotides at the 3' end. Complete sequence can be generated in conjunction with snake venom phosphodiesterase digestion of purified material. This method eliminates difficulties associated with other mass spectrometric sequencing techniques involving oligonucleotide length; structure; and sugar, base, and backbone modifications. Examples of sequencing a 17-mer composed primarily of 2'-O-methylribonucleotides and a single nonnucleosidic linker and a mixed sugar backbone 51-mer with 2'-O-methylribonucleotides and a homopolymer tail are reported in this study.

Oligonucleotides↗
PubMed2002

Autologous versus allogeneic unrelated donor transplantation for acute lymphoblastic leukemia: comparative toxicity and outcomes.

For patients with high-risk or relapsed acute lymphoblastic leukemia (ALL) lacking a related histocompatible donor, autologous (Auto) and unrelated donor (URD) transplantation are available options. We compared outcomes and toxicities in 712 patients with ALL (517 URD, 195 Auto) in first complete remission (CR1) or second complete remission (CR2) who underwent transplantation. All patients were <50 years old, although URD patientswere younger (median age, 14 versus 18 years, P < .002). The proportion of patients in CR1 versus CR2 was similar (36% versus 38%, P = .57), but more URD recipients than Auto recipients had high-risk karyotypes (25% versus 13%, P = .003) and white blood cell (WBC) counts > or =50 x 10(9)/L (33% versus 14%, P < .001). Engraftment was similar in URD and Auto recipients. Ex vivo purging delayed but did not prevent engraftment after Auto transplantation. Transplantation-related mortality was higher after URD transplantation (42%+/-8%) than after Auto transplantation (20%+/-12%) in CR1 (P = .004) and also in CR2. Conversely, relapse was more frequent after Auto transplantation in CR1 (Auto, 49%+/-12% versus URD, 14%+/-5%) and CR2 (64%+/-8% versus 25%+/-5%) (P < .0001). These findings showed net similar outcomes for these 2 transplantation choices. Transplantation in CR1 yielded similar 3-year survival rates for URD (51%+/-7%) and Auto (44%+/-12%), as did transplantation in CR2 (40%+/-6% versus 32%+/-9%, respectively). Multivariate regression analysis identified significantly better disease-free survival after the first 6 months in matched URD versus Auto in younger patients, in those in CR2 with CR1 >1year, WBC <50 x 10(9)/L, performance status > or =90%, and in those who have undergone transplantation since 1995. These comparative data suggest that both matched URD and Auto transplantation can yield extended survival. Although URD transplantation offers substantially better protection against leukemic relapse, improvements in allotransplantation safety and refinements in patient selection are required to better aid treatment decision making for the best overall survival.

Adolescent↗
PubMed2002

Iodination of annexin V for imaging apoptosis.

UNLABELLED: Our goal in this investigation was to develop a method for iodinating annexin V that would be suitable for the in vivo detection of apoptosis. METHODS: Annexin V was iodinated with (125)I using 2 different techniques: direct iodination with IODO-BEADS, resulting in the iodination of tyrosine residues; and use of the Bolton-Hunter reagent, which binds to lysine. The active fraction of the labeled preparation was purified by affinity chromatography. We assessed thyroid accumulation of free iodide by comparing mice with blocked and unblocked thyroids. We tested the ability of iodinated annexin V to bind apoptotic cells in vitro using irradiated neuroblastoma cells and immobilized phosphatidylserine and in vivo using C3H mice subjected to whole-body irradiation. RESULTS: The efficiency of IODO-BEADS iodination was just below 30%; with the Bolton-Hunter protocol we were able to achieve 40% efficiency. When the IODO-BEADS-labeled preparation was injected into nude mice, activity accumulated rapidly in the thyroid. Two hours after injection, uptake in the thyroid region was clearly visible on a gamma-camera scan. This uptake was absent in mice that had had their thyroids blocked. We concluded that the IODO-BEADS method of labeling resulted in a protein that was rapidly deiodinated in vivo. By contrast, when annexin V was labeled using the Bolton-Hunter protocol, there was no evidence of activity accumulating in the thyroid. The Bolton-Hunter-labeled annexin V bound to apoptotic cells and immobilized phosphatidylserine in vitro. The active fraction of Bolton-Hunter-labeled annexin V was approximately 0.75. In C3H mice given 5-Gy whole-body irradiation, there was a significant induction of apoptosis in the spleen, as measured by the terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay, and a 4-fold increase in (125)I activity in the spleens relative to that of the control animals. CONCLUSION: Direct iodination of annexin V on tyrosine residues is a poor technique suffering from rapid deiodination in vivo. With Bolton-Hunter chemistry, one can produce a molecule that retains its label in vivo and binds to apoptotic cells in vitro and in vivo.

Animals↗