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Biomedical subjects

D Barnes

Publications and source records attributed to D Barnes.

At least 163 records · Page 9Linked to original sources
PubMed1989

Quantifying postoperative deficits of physical function following spinal surgery.

This study evaluates the degree of objectively quantified physical deconditioning of spinal surgery patients. The object is to evaluate the data in terms of the pain and disability claimed by 35 male and 11 female patients three months after spinal surgery. Among the males, two subgroups (i.e., disc excision or spinal fusion) were evaluated. All patients reported subjective indices of pain/disability and completed quantified tests of lumbar motion, sagittal trunk strength, lifting capacity, and bicycle ergometry. In general, true lumbar motion was markedly restricted to 50%-60% and trunk strength means were below 50% of gender-specific normative values. There were similar deficits for lifting capacity. Those who had spinal fusions tended to perform poorly, with a relatively high incidence of pain/disability. There were no differences found between the male group and subgroups who were gainfully employed or had a brief period of disability prior to surgery or had low subjective pain/disability. These results indicate that a patient's subjective pain/disability were not a reliable measure of functional capacity by three months postoperatively. Regardless of working status, pain level, or brevity of disability, there was a significant loss of performance ability and risk of persistent dysfunction after surgical treatment.

Adult↗
PubMed1989

Activation of the trk oncogene by alternatively spliced muscle and non-muscle tropomyosin sequences.

We have constructed a derivative of the trk oncogene in which the cytoskeletal tropomyosin sequences are replaced with skeletal muscle alpha-tropomyosin sequences derived from the same tropomyosin gene by alternative splicing. The biochemical and biological properties of this derivative are indistinguishable from those of the naturally occurring trk oncogene. Thus activation of the oncogenic activity of trk is a function of structural features of tropomyosin which are common to both skeletal muscle and non-muscle isoforms.

Animals↗
PubMed1988

19F NMR imaging of blood oxygenation in the brain.

Perfluorocarbon (PFC) emulsions have been developed as oxygen carrying blood substitutes. High fluorine concentrations allow them to be used in 19F NMR imaging of blood vessels. Furthermore, 19F relaxation times in PFCs are dependent on oxygen tension (pO2) so that NMR imaging may provide a noninvasive method of measuring spatially localized pO2 values in vivo. Using these principles, we have formed 19F images and calculated pO2 maps of the cat brain.

Animals↗
PubMed1988

The characterization of experimental gliosis by quantitative nuclear magnetic resonance imaging.

Quantitative nuclear magnetic resonance imaging techniques were used to study the development of astrocytic gliosis following a cortical freezing injury in 4 cats, and the findings compared with the histological and ultrastructural appearances of the affected white matter. In the first week after lesioning, the acutely oedematous white matter was apparent as a region of signal abnormality with very prolonged T1' and T2' relaxation times. Following resolution of this oedema, the images remained normal for a period of approximately three months. After this latent period they became abnormal once again, and the abnormal signal was most evident in images emphasizing differences between tissues in T1' and proton density, but not T2'. The light and electron microscopic appearances of the corresponding tissue were of astrocytic gliosis in each animal. Measurement of the relaxation times, T1' and T2', of the abnormal regions revealed an increase in T1' without a corresponding change in T2'. The T2' magnetization decay characteristics were consistently monoexponential, in contrast to the clearly biexponential T2 decay which has previously been demonstrated in the presence of acute vasogenic oedema. These findings suggest that the pattern of change of the relaxation times and T2 magnetization decay might provide a means of distinguishing between lesions in multiple sclerosis which are predominantly gliotic, and those containing significant amounts of oedema.

Animals↗
PubMed1988

Serial gadolinium enhanced magnetic resonance imaging in multiple sclerosis.

Serial gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging (MRI) was performed in 9 patients with multiple sclerosis (MS). On the first scan enhancing lesions were seen in 7 patients, all of whom were in acute relapse. Most enhancing lesions were asymptomatic. On the second scan (3 to 5 weeks later), persisting enhancement was seen in only 12/54 lesions which enhanced on the first scan. No lesion showed persisting enhancement on the third scan (after 6 months). Enhancement occurred in all 12 new lesion areas seen on the unenhanced second scan and in 8 of 15 new lesions seen on the third scan. Enhancement was also seen in 4 older lesions which had been nonenhancing on earlier scans. Relaxation time measurements demonstrated a high water content in some nonenhancing lesions, which could be due to a subtle blood-brain barrier disturbance not detected with Gd-DTPA. The results show that blood-brain barrier impairment is a consistent finding in new MS lesions detected with MRI. Gd-DTPA is a useful marker of new and biologically active lesions and should prove of value in monitoring therapeutic trials in MS.

Adult↗
PubMed1988

Progressive isoinertial lifting evaluation. I. A standardized protocol and normative database.

Dynamic tests of trunk strength and lifting capacity have become more popular in recent years, offering certain advantages over static isometric tests in measuring patient progress in functional restoration programs for spinal disorders. However, equipment for performing such tests is expensive to buy, complex to run, and requires technical expertise and clinical volume unavailable in most physician offices. In this study, a new dynamic test known as Progressive Isoinertial Lifting Evaluation (PILE) is described, which draws upon prior psychophysical and isoinertial methods. An industrial sample of 61 male and 31 female incumbent workers were tested using the PILE, and a variety of anthropometric normalizing factors were evaluated. The isolation of an "Adjusted Weight" (AW) normalizing factor is documented, after which normative data are presented for male and female workers utilizing lumbar (0-30 inches) and cervical (30-54 inches) dynamic protocols.

Adult↗
PubMed1988

Changing dentists' knowledge, attitudes, and behaviors relating to AIDS: a controlled educational intervention.

The efficacy of an educational intervention designed to improve dentists' knowledge, attitudes, and behaviors about acquired immune deficiency syndrome (AIDS) was tested. The intervention had three components: computerized feedback comparing participants' own knowledge, attitudes, and behaviors with those of fellow participants and with an ideal; periodic bulletins; and telephone conference calls with experts. The group receiving the educational package had better scores than a control group on outcomes of willingness to treat persons with AIDS; identification of human immunodeficiency virus lesions; knowledge of AIDS; and completeness of both intraoral and extraoral examinations. It was concluded that intervention is one approach to increasing dentists' positive response to the AIDS epidemic.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Progressive isoinertial lifting evaluation. II. A comparison with isokinetic lifting in a disabled chronic low-back pain industrial population.

The Progressive Isoinertial Lifting Evaluation (PILE), as described in Part I of this series of articles, is a simplified test combining psychophysical and isoinertial protocols to provide an unconstrained lifting assessment. In the second part of this study, 100 chronically disabled low-back pain patients (57 men and 43 women) were studied at two points: 1) at initial evaluation, when referred for possible entry into a comprehensive Functional Restoration treatment program; and 2) at the conclusion of the treatment (an average 7 weeks later). Results of simultaneous lumbar PILE and Cybex Liftask (Lumex, Ronkonkoma, NY) tests are presented, showing that patients may frequently double or triple initial lifting capacity after undergoing the functional restoration training program, achieving lifting levels at or above normal for incumbent industrial workers. Overall, results demonstrate that the PILE test can be an effective baseline screening test for lifting capacity under certain circumstances. Although several drawbacks affecting the PILE as an isolated test are discussed, its usefulness as part of a battery of physical capacity tests making up a quantitative functional evaluation is clearly demonstrated. Finally, the potential use of PILE as a safe, inexpensive, simple, and relevant screening test for frequent lifting capacity in worker selection is discussed.

Back Pain↗
PubMed1987

Comparison of DNA interstrand cross-linking and strand breakage by 1,3-bis(2-chloroethyl)-1-nitrosourea in polyamine-depleted and control human adenocarcinoma cells.

Recent evidence from our laboratory and from others suggested that pretreatment with alpha-difluoromethylornithine (DFMO) sensitizes some human and rodent tumor cell lines to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Many human tumor cells are resistant to chloroethylnitrosourea-induced DNA interstrand cross-linking and cell kill due to their high levels of the DNA repair protein O6-alkylguanine DNA alkyltransferase. We therefore investigated DFMO-mediated sensitization to BCNU in BCNU-sensitive and -resistant cells. Colony formation assays were used to compare BCNU cytotoxicity in DFMO-pretreated and control cultures of two colon tumor lines, HT-29 cells, which have high alkyltransferase levels and thus are BCNU-resistant, and BE cells, which are deficient in this repair capacity and thus are BCNU-sensitive. Polyamine depletion significantly enhanced BCNU cytotoxicity only for the repair-proficient HT-29 cell line. BE cells were 40-fold more sensitive to BCNU than were HT-29 cultures. However, in BE cells, no effect of polyamine depletion was found on cellular response to BCNU treatment at 72 h after DFMO treatment. Reverse-phase high-performance liquid chromatography assays of polyamine concentrations in cell extracts verified that DFMO produced comparable degrees of polyamine depletion for both cell lines. DNA alkaline elution analysis was used to monitor BCNU-induced formation of DNA single strand breaks, DNA interstrand cross-links, and DNA-protein cross-links. Equal concentrations of BCNU produced similar levels of strand breaks and DNA-protein cross-links in DFMO-pretreated and control cultures for both cell lines. These data suggest that DNA in polyamine-deficient HT-29 and BE cells is not more accessible to BCNU than is DNA in controls. No DNA interstrand cross-links were detected in either DFMO-pretreated or control HT-29 cells after BCNU treatment. Further, in BE cells which accumulate BCNU-induced DNA interstrand cross-links, no increase in the measureable levels of cross-links resulted from polyamine deficiency. Our observations suggest that mechanisms other than increased DNA interstrand cross-link formation may be mediating the enhanced efficacy of BCNU in polyamine-deficient HT-29 cell cultures. Our findings may also imply that cellular targets for BCNU other than DNA damage may be responsible for DFMO-induced chemosensitization in the repair-proficient cells.

Adenocarcinoma↗
PubMed1987

STIR sequences in NMR imaging of the optic nerve.

Orbital fat surrounding the optic nerve causes considerable difficulties in NMR imaging due to its high image intensity and the chemical shift artefact. We have investigated the ability of inversion recovery sequences with short inversion times (STIR sequences) to suppress fat signals in imaging the optic nerve. We have also compared the contrast attainable with STIR sequences with that obtainable from other sequences. Measurements were made on 4 normal controls and 5 patients with multiple sclerosis (MS) to obtain typical values of relaxation times and proton densities for orbital fat, cerebral white matter and MS lesions. The fat T1 measurements were used to predict an appropriate inversion time for the STIR sequence and estimate how much residual fat signal might be expected as a result of natural variations in fat T1. STIR sequences can be used to suppress the signal from orbital fat with little residual signal. Measurements from white matter and MS lesions were used to predict the contrast between normal and pathological tissues that is attainable with STIR sequences. STIR contrast compares favourably with that obtainable from other sequences.

Humans↗