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Biomedical subjects

L Barr

Publications and source records attributed to L Barr.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prospective randomized controlled trial of preservation of the intercostobrachial nerve during axillary node clearance for breast cancer.

BACKGROUND: Complications of axillary surgery occur due to severance of the intercostobrachial nerve (ICBN). The feasibility and benefit of preserving the ICBN to prevent sensory loss was studied prospectively. METHODS: Sensory symptoms and deficits were documented, and shoulder movement and arm circumference were measured at discharge and 3 months later in 120 patients randomized to either preservation or division of the ICBN. RESULT: Preserving the ICBN was feasible in 39 (65 per cent) of the 60 patients randomized to the preservation group. Preserving the nerve prolonged the procedure by a median of 5 min. No difference in sensory symptoms between the groups was seen at 3 months. At 3 months 53 per cent of patients randomized to ICBN preservation had a sensory deficit compared with 84 per cent of those randomized to ICBN sacrifice (P < or = 0.05). CONCLUSION: Preserving the ICBN reduces the incidence of sensory deficit (but not symptoms) in patients after axillary clearance.

Adult↗
PubMed1993

Adult type (nonembryonal) soft tissue sarcomas in childhood.

Nonembryonal soft tissue sarcomas are rare in childhood. We report our experience from a series of 28 patients treated at this centre, whose treatment was based on primary surgical resection. No patient required limb amputation. Anatomical distribution and histological subtypes differed from the adult sarcoma population. A total of 79 percent of the sarcomas were classified as high grade. Six patients (21%) developed local recurrence, and 6 patients (21%) developed distant recurrence, including 3 patients (11%) who developed both. Median follow-up was 57 months. Actuarial 5 years survival was 82%, which compares favorably with the 5 year survival of adults with high grade soft tissue sarcomas treated at this centre (63%) and with the survival of children with embryonal sarcomas treated by chemotherapy.

Adolescent↗
PubMed1993

Technical note: appearances on ultrasound of impalpable injection port in a double chamber breast prosthesis.

Breast reconstruction utilizing tissue expansion is being increasingly practised by both plastic and general surgeons. Our current experience for both immediate and delayed reconstruction is with the double chamber Becker prosthesis. The prosthesis with the resulting breast mound has on occasions rendered the injection port difficult to localize by palpation. We have found ultrasound useful in identifying impalpable ports and in facilitating needle insertion into the injection dome.

Female↗
PubMed1992

Four-state models and regulation of contraction of smooth muscle. I. Physical considerations, stability, and solutions.

Cyclic four-state models are frequently used in biology to represent a variety of molecular behaviors. A common experimental strategy to test such models is to follow the behavior of the real system after some of the rate constants are changed in a stepwise manner. We analyze the mathematical behavior of a simple example of such a model applicable to the regulation of contraction of smooth muscle, but our results apply in general to any linear, cyclic four-state model. We discuss detailed balance and requirements for linearity. We find that the only way to have sustained oscillations is for the rate constants of the model to be themselves oscillatory. We state conditions for decaying oscillations and find that in models that do not follow strictly first-order kinetics and do not satisfy detailed balance, these conditions can hold. We show analytically that the response of any state to step changes in the rate constants is the sum of three weighted exponentials plus a constant term, the steady-state value. We provide explicit expressions for the time dependence of all state variables. We discuss a simple way to use these results to obtain numerical solutions in cases where the rate constants change in an arbitrary way.

Animals↗
PubMed1992

Four-state models and regulation of contraction of smooth muscle. II. Properties of the solutions and identification.

We analyze the behavior and the identification problem of cyclic four-state models. We find that for any state, or a weighted combination of two states, there can be at most one maximum, or one minimum, and two inflection points. We obtain necessary conditions for overshoot and undershoot and give examples. We describe procedures to estimate all the rate constants and discuss certain experimental aspects of the identification problem. Finally, we give an example of identification by obtaining the 10 model parameters from experimental data on skinned fibers from smooth muscle. These results, in conjunction with the results of the previous paper, can help in testing four-state models of regulation of contraction of smooth muscle and of a variety of other physiological and biochemical phenomena.

Animals↗
PubMed1991

Chondrosarcoma of the pelvis: the role of palliative debulking surgery.

Curative resection of pelvic chondrosarcoma is sometimes technically impossible. In such cases, surgical debulking on one or more occasions may provide symptomatic relief. In a series of 12 patients with pelvic chondrosarcoma, three have undergone a single debulking procedure and three two or more such procedures. All six patients obtained symptomatic relief and five remain alive and well at a median of 12 months from surgery. Two patients have no clinical evidence of recurrent disease 21 and 25 months after the last debulking procedure.

Adolescent↗
PubMed1990

Treatment of extremity soft tissue sarcomas with surgery and radiotherapy.

The results of treatment with a combination of surgery and radiotherapy of 102 patients with nonmetastatic extremity soft tissue sarcoma are reported. Seventy-nine patients were previously untreated and 23 had locally recurrent disease. Sixty-six tumours were situated in the lower limb and 16 in the limb girdles. Fifty-nine were high grade lesions, and 64 were over 5 cm in length. Surgical clearance was "good" (wide or radical) in only 34 cases. Sixty-eight patients received post-operative irradiation, 23 pre-operative irradiation and 11 both pre- and post-operative radiotherapy. Seventeen patients subsequently developed local recurrence and 9 of these remain disease-free after further surgery. Actuarial 5 year local control and disease-free survival rates for new cases were 87 and 65.4%; and for previously recurrent cases these figures fell to 75 and 54.8%. Following a univariate analysis of patient, tumour, surgical and radiotherapeutic factors only previous local recurrence (p less than 0.1 greater than 0.05) was found to significantly increase the risk of further local relapse. Multivariate analysis found high tumour grade [relative risk (RR) 8.4], tumour size greater than 15 cm (RR 3.66), previous local recurrence (RR 6.47) and proximal site (RR 12.7) to be independent poor risk factors for survival.

Actuarial Analysis↗
PubMed1989

Immunocytochemistry of the interstitial cells of Cajal in the rat intestine.

There is experimental evidence suggesting that the interstitial cells of Cajal are essential for rhythmic slow waves of the smooth muscle layers of the mammalian small intestine. Different investigators have identified them variously as modified neurons, glia, fibroblasts or modified smooth muscle cells. Since histological categorization bears on understanding their function, we have examined the immunoreactivity of the myenteric plexus of the rat small intestine, paying special attention to the cell type identified as Thuneberg's Type I-ICC. Polyclonal and monoclonal antisera directed against 4 intermediate filament proteins: neurofilament protein, glial fibrillary acidic protein, vimentin and desmin were used. In addition, antisera directed against neuron-specific enolase, substance P and vasoactive intestinal polypeptide were also tested for reactivity. Type I-ICCs were immunonegative to all the antisera directed against intermediate filament proteins and neuropeptides. However, some Type I-ICCs were immunopositive to antisera against neuron-specific enolase. On the basis of these results and the distribution of immunoreactivities to these kinds of antisera in other tissues, we suggest that Type I-ICCs are distinct from typical myenteric neurons, from glia, from fibroblasts and from smooth muscle fibers. Staining with antiserum against neuron-specific enolase suggests a relation to some type of neuron.

Animals↗
PubMed1989

Paget's disease of the nipple occurring after wide local excision and radiotherapy for carcinoma of the breast.

Between 1979 and 1985, 356 cases of Stage I or II breast carcinomas have been treated at Westminster Hospital with breast conservation. Of these patients, 338 underwent local excision and radiotherapy and there have been 38 local recurrences. Three of these have been as Paget's disease of the nipple occurring 16, 8 and 5 months following radiotherapy. In each case the nipple appearances were attributed to postradiotherapy changes; the true diagnosis was not made for an average of 19 months. The increasing use of conservative breast management for early breast tumours permits the appearance of Paget's disease as a significant proportion of local recurrences. Previously this has been considered to be a rare event. We recommend that Paget's disease of the nipple should be suspected early following radiotherapy in the presence of any nipple changes.

Aged↗
PubMed1989

Photomechanical coupling in the vertebrate sphincter pupillae.

The photomechanical response of the vertebrate iris sphincter pupillae isolated from irises of many species of vertebrates contract when light is shined on them. It appears that the cell membranes of the constituent smooth muscle cells contain rhodopsin which triggers the photomechanical response (PMR) when bleached. In amphibians and some fish this mechanism of pupillary control is more important than the more well-known retinal reflex. In the mammals the retinal reflex is more important; however, even in the mammals the exact role of the innervation is not understood. The PMR can be inhibited by beta adrenergic agonists but not by alpha adrenergic agonists. The activation sequence of the PM probably involves (1) rhodopsin activated G-protein, (2) phospholipase C, (3) inositol triphosphate, and (4) a calcium-calmodulin-myosin light chain kinase cascade. A simple mathematical version of the phosphorylation theory of smooth muscle contraction accurately predicts the time courses of PMRs to light stimuli of different durations and intensities.

Animals↗
PubMed1988

Hypersensitivity to light of the iris (Sphincter pupillae) of the albino axolotl (Ambystoma mexicanum).

As is common for amphibians, the sphincter pupillae of the axolotl contracts in vitro in response to illumination with visible light. 1. In a comparison of photomechanical responses of albino and normally pigmented axolotls, similar time courses and maxima of force development were found. 2. The dependence of isometric active force development on the length of the sphincter pupillae is similar to that of other smooth muscles. 3. The action spectrum of the axolotl is similar to the absorption spectrum of frog rhodopsin. 4. At low stimulus strengths, the increase of normalized, isometric, active force with increasing stimulus strength is approximately seven times as great in albino axolotls as in normally pigmented ones. 5. Melanin appears to decrease the light sensitivity of the irises of normally pigmented animals by acting as a simple light shield.

Albinism↗
PubMed1988

Organisation of community nursing services.

The Cumberlege Report proposal for a neighbourhood nursing service is attractive, but does it need more nurse managers? Sheila Rogers and Lex Barr argue that it does not.

Administrative Personnel↗