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Biomedical subjects

S C Hardy

Publications and source records attributed to S C Hardy.

26 records · Page 2Linked to original sources
PubMed1991

Pharmacological manipulation of gastrocnemius muscle blood flow in an animal model of reperfusion injury.

Despite technically satisfactory surgery for acute lower limb ischaemia reperfusion injury may result in failure of limb salvage and the need for amputation. An animal model using the rat hind limb has been developed which demonstrates this complication. A tourniquet was applied to one hind limb for 6 h and then released. Gastrocnemius muscle blood flow in both hind limbs was assessed using radiolabelled microspheres and a perfusion index calculated between the revascularized and normal hind limbs and the results compared with similar measurements in control animals and rats with a tourniquet still in situ (ischaemic). Following 10 min the median perfusion index in reperfused animals was significantly less than that in control animals (0.12 +/- 2 inter-quartile range 0.02-0.43) versus 1.05 (0.68-1.18), P less than 0.01) but similar to the results in rats with a tourniquet still in situ [0.04 (0.00-0.07), ns], thus demonstrating low reflow following tourniquet release. After 120 min revascularization a phase of relative reperfusion occurred with perfusion indices becoming higher than those in animals with a tourniquet in situ (0.48 (0.11-0.70) versus 0.02 (0.01-0.07), P less than 0.05) but remaining lower than those in control rats [0.97 (0.79-1.13), P less than 0.05]. Finally after 240 min, reperfusion injury occurred with perfusion being similar to that in animals with a tourniquet applied [0.05 [0.01-0.38) versus 0.03 (0.00-0.07), ns] and less than that in the normal rats [1.01 (0.73-1.16), P less than 0.01].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Localization of nuclear matrix proteins (NMPs) in multiple tissue types with NM-200.4 (an antibody strongly reactive with NMPs found in breast carcinoma).

Nuclear matrix proteins (NMP) are nonhistone proteins found in the nucleus of many eukaryotic cells. Furthermore certain NMPs are reported to be cell-type specific and expressed differentially by malignant cells. To study the specificity of NM-200.4 (an antibody reactive to NMPs extracted from cultured breast carcinoma cells of the T-47D line), cancers and benign tissues from multiple body sites were surveyed. All 17 breast carcinomas showed strong reactivity to tumor cell nuclei. Also nuclei from one of two lung carcinomas, a papillary thyroid carcinoma, an ovarian fibroma, and a lymphoma were strongly reactive. One leiomyosarcoma and a dermoid cyst were negative. Although 1 benign breast with duct hyperplasia showed moderate reactivity, only 1 of 10 benign breast biopsies without hyperplasia showed reactivity. Three of 4 skin biopsies, 2 liver biopsies, 6 of 9 kidney biopsies, and 5 of 10 gastrointestinal mucosal biopsies showed reactivity in benign nuclei. It is concluded that, although breast carcinoma nuclei showed the most consistent reactivity for NM-200.4, both benign and malignant nuclei from other body sites also show reactivity.

Animals↗
PubMed1990

The triphasic pattern of skeletal muscle blood flow in reperfusion injury: an experimental model with implications for surgery on the acutely ischaemic lower limb.

A new model of acute lower limb ischaemia has been developed in the rat hind limb. The model has been used to examine the influence on skeletal muscle blood flow of increasing periods of ischaemia and reperfusion. Following restoration of blood flow after 2-6h ischaemia initial gastrocnemius muscle blood flow was reduced. The severity of initial low reflow, indicated by mean perfusion ratios at 0 and 10 min, correlated with the duration of preceding ischaemia (r = 0.83, p less than 0.05) and was greatest in limbs subjected to 6h ischaemia (p less than 0.01 vs. controls at 0, 10 and 60 min after revascularisation). After 60-240 min, reperfusion muscle blood flow returned to normal in limbs subjected to 3, 4 or 5 h ischaemia. In contrast, peak muscle blood flow in limbs that had been ischaemic for 6 h occurred after 120 min, although perfusion remained less than that measured in control limbs (p less than 0.05:6 h ischaemia, 120 min vs. control)-(relative reperfusion). Limbs reperfused after 6 h ischaemia demonstrated a subsequent decline in muscle blood flow between 120 min and 240 min following revascularisation (p less than 0.05). In addition, muscle blood flow at 240 min was no different to that in a totally ischaemic limb (p less than 0.01 vs. controls; ns vs. ischaemic limb) thus representing reperfusion injury.

Animals↗
PubMed1988

Small lateral suprasylvian cortex lesions produce visual neglect and decreased visual activity in the superior colliculus.

Previous experiments in cats have shown that complete contralateral visual neglect is produced by removing all known visual cortex on one side of the brain, which can then be reversed by damaging the opposite superior colliculus. Presumably, descending facilitatory influences from the visual cortex to the ipsilateral superior colliculus are counterbalanced by intercollicular inhibition (Sprague: Science 153:1544-1546, '66). However, not all of visual cortex or all of the superior colliculus needs to be involved in this circuit. It is the deep rather than the superficial laminae of the superior colliculus that are primarily involved in visual attentive and orientation behaviors, and these laminae are largely independent of primary visual cortex. However, they do depend on corticotectal influences from a comparatively small extraprimary visual area of the posterior region of the lateral suprasylvian cortex (PSSC-Ogasawara et al: J. Neurophysiol. 52:1226-1245, '84). The present experiments demonstrate that lesions only a few millimeters in diameter in this corticotectal zone of the PSSC can produce profound visual neglect. While damage to this area has little, if any, effect on superficial laminae visual activity, it produces a dramatic decrease in the visual activity of the deep laminae. These cats with PSSC lesions fail to orient to a visual stimulus that is introduced suddenly into the contralateral visual field, yet they respond on nearly 100% of the trials to this same stimulus when it is presented in the ipsilateral visual field. The lesion-induced visual neglect produced by PSSC lesions is long-lasting but can be abruptly ameliorated by a midbrain lesion that primarily involves, or undercuts, the deep laminae of the contralateral superior colliculus. Thus, 1) visual neglect can be produced by depriving the deep laminae of the superior colliculus of visual inputs from the cortex, even when the principal visual cortical regions (17, 18, and 19) and their target structures are intact, and 2) visually guided behavior can be restored by eliminating afferents originating in, or passing through, the deep laminae of the contralateral superior colliculus.

Animals↗
PubMed1982

Effect of radiolabeled materials on tracheal mucous clearance in beagle dogs.

Studies of tracheal mucous clearance were carried out in 6 beagle dogs using a wide range of instilled activities. The dogs were anesthetized with halothane and then 2 separate 10-microliter droplets were deposited, 1 reference droplet containing 25 muCi of 67Ga on the left side of the carina and 1 containing either 3, 50, 250, 500, or 1,000 muCi 99mTc on the right side of the carina. Simultaneous measurements of the positions of the droplets were made every minute for 25 min using a gamma camera detection system. There were no differences in velocities with increasing 99mTc activity. The movements of labeled (100 muCi) and unlabeled Teflon-bismuth discs were also compared. No significant differences were detected but the labeled discs did have slightly higher velocities.

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