PubMed Health⌕ Search

Biomedical subjects

J R Cooper

Publications and source records attributed to J R Cooper.

At least 19 recordsLinked to original sources
PubMed2000

Distribution of sonographically detected tendon abnormalities in patients with a clinical diagnosis of chronic achilles tendinosis.

PURPOSE: We conducted a retrospective study of the distribution of sonographically detected abnormalities in the heels of patients who had a clinical diagnosis of Achilles tendinosis. METHODS: One hundred eighteen symptomatic heels in 73 patients who had a clinical diagnosis of chronic Achilles tendinosis were examined over a 12-month period by the same experienced sonologist. The distribution of altered tendon architecture and features suggesting retrocalcaneal bursitis or Achilles paratendinosis were evaluated. RESULTS: Sonograms of 118 symptomatic heels demonstrated that 96 (81%) had abnormalities confined to the proximal two thirds of the Achilles tendon, 9 (8%) had abnormalities in the distal third alone, and 13 (11%) had abnormalities at both sites. Of the 109 heels with proximal two-third Achilles tendon disease, 99 (91%) had medial tendon involvement; 22 of the 99 showed diffuse tendon changes. Lateral tendon segment changes were seen in 22 (19%) of the 118 symptomatic heels. No lateral tendon segment was involved in isolation. Of the 22 heels with distal third abnormalities, 14 (64%) had sonographic evidence of Achilles paratendinitis, and 13 (59%) had sonographic evidence of Achilles tendinosis. Eighteen of the 22 had sonographic evidence of retrocalcaneal bursitis. In all cases of distal third tendinosis, the deep surface of the tendon was primarily involved. In the heels with both proximal and distal changes, superficial segment involvement of the mid-Achilles tendon was present. CONCLUSIONS: Sonography provides information that helps to accurately diagnose clinical Achilles tendinopathy and may help to determine the biomechanical processes involved in the injury.

Achilles Tendon↗
PubMed2000

Brainstem frequency-following response and simple motor reaction time.

Simple motor reaction times (RT) in humans show marked trial-to-trial variations. In the present study, a brief tone (400 Hz, 37.5 ms duration) that was the imperative stimulus in a RT paradigm evoked the brainstem frequency-following response (FFR). Horizontal and vertical montage FFRs were recorded to evaluate neural responses with putative origins in auditory nerve and central brainstem, respectively. The main question concerned the possible relationship between trial-to-trial variations in RT speed and FFR response properties. The results showed a reliable pattern in which fast RT trials yielded larger amplitudes (relative to slow trials) in earlier milliseconds of the FFR, and slow RT trials yielded relatively larger amplitudes in later milliseconds of the response. These results support the conclusion that early processing in the auditory brainstem is not automatic and invariant. Rather, short-latency evoked potentials appear to reflect trial-to-trial variations related to events far removed from the first synapse of sensory coding, perhaps depending upon cortically mediated influences such as cognition or attention.

Acoustic Stimulation↗
PubMed2000

Butyric acid is synthesized by piglets.

We hypothesized that there is no synthesis of butyric acid within organs or tissues not drained by the portal vein (PV). Two experiments were performed. In six piglets, the colonic vasculature was clamped (n = 4) or the entire colon resected while [1-13C]-butyric acid (99% enriched) was infused into a jejunal vein for 120 min; 13C enrichment of butyric acid was measured in the PV and carotid artery (ART) during the last 30 min of the infusion. In a second experiment, butyric acid tracer and unlabeled disaccharide were infused into the cecum for 120 min, and blood again was sampled from the PV and ART. For the four piglets studied during ligation of the colonic vasculature, the mean (+/- SD) ratio of the butyric acid enrichment in the ART to that in the PV (ART/PV) was 0.80+/-0.05 (ART vs. PV, P = 0.002) and for all six piglets in expt. 1, the ART/PV ratio was 0.74+/-0.1 (ART vs. PV, P = 0.001). The enrichment of butyric acid in the PV averaged 96.0% for the six studies, implying that splanchnic tissues other than the colon did not produce a substantial amount of butyric acid. For the second experiment, the ART/PV ratio was 0.80+/-0.15 (ART vs. PV, P = 0.03). These studies provide the first evidence for endogenous synthesis of butyric acid by piglets.

Animals↗
PubMed1999

Induction of vascular cell adhesion molecule-1 expression by IL-4 in human aortic smooth muscle cells is not associated with increased nuclear NF-kappaB levels.

Vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) are upregulated in vascular endothelial and smooth muscle cells by cytokines produced at sites of inflammation. The cytokine profile for induction of VCAM-1, however, is different for the two cell types. Tumor necrosis factor-alpha (TNF-alpha) induced both VCAM-1 and ICAM-1 expression in human umbilical vein endothelial cells (HUVECs; ED50 approximately 300 and 30 U/ml, respectively). TNF-alpha and interleukin-1beta (IL-1beta) stimulated cell surface ICAM-1 expression, but not VCAM-1 expression, in human aortic smooth muscle cells (HASMCs). Conversely, IL-4 was a potent VCAM-1 inducer in HASMCs (ED50 approximately 100 pg/ml) but did not induce ICAM-1 expression. Nuclear extracts from IL-4-treated cells were compared with untreated cells for relative nuclear factor-kappa B (NF-kappaB) levels by using an electrophoretic mobility shift assay and surface plasmon resonance techniques. No significant increase in nuclear NF-kappaB DNA binding activity was detected in IL-4-treated HASMCs by either method of analysis. IL-1beta and TNF-alpha stimulated nuclear NF-kappaB levels by about fourfold and fivefold, respectively, in HASMCs. The antioxidant pyrrolidine dithiocarbamate (PDTC) similarly inhibited VCAM-1 upregulation in HASMCs incubated with IL-4 and in HUVECs incubated with TNF-alpha (IC50s of 25 and 40 microM, respectively). These data suggest that a significant increase in nuclear NF-kappaB levels is not necessary or sufficient for VCAM-1 upregulation in HASMCs and does not determine the relative sensitivity to inhibition of gene expression by PDTC.

Aorta↗
PubMed1999

Magnetic resonance imaging of injuries in the child athlete.

Sports related injuries in children and adolescents are an increasingly frequent clinical problem. Soft tissue injury is relatively less common in children than in adults and radiographs suffice in most situations. However there are specific clinical circumstances where MR imaging is of value. We discuss and demonstrate a variety of acute and chronic sports related conditions where MR imaging has contributed to the diagnosis and management. Some conditions such as apophysitis, osteochondritis and chronic physeal injuries are unique to childhood while others including spondylysis and stress fractures are unusual conditions outside the context of sport in this age group.

Adolescent↗
PubMed1999

Sonographic incidence of tendon microtears in athletes with chronic Achilles tendinosis.

OBJECTIVE: To assess the number and distribution of tendon microtears in asymptomatic controls and athletes with chronic Achilles tendinitis or partial thickness tears using high resolution ultrasound. METHODS: The mean number of microtears in three random tendon cross sections were recorded per tendon third in 19 asymptomatic volunteers, 16 athletes with symptomatic chronic Achilles tendinitis, and eight athletes with partial Achilles tendon rupture. RESULTS: Microtears were most numerous in the middle third section of the Achilles tendon. Some 67% of tendons in the control group had no microtears, and 28% showed a single microtear. Only 18% of the athletes with chronic Achilles tendinitis and none of the athletes with partial tendon rupture were without microtears in the middle third of their Achilles tendon. Of the tendons with chronic tendinitis, 13% had more than three microtears per section which increased to 87% in tendons exhibiting partial rupture. CONCLUSIONS: There appears to be an association between microtear formation and Achilles tendon rupture.

Achilles Tendon↗
PubMed1998

Proximal aneurysms in association with arteriovenous malformations: do they resolve following obliteration of the malformation with stereotactic radiosurgery?

One-hundred consecutive patients were identified who had arteriovenous malformations (AVMs) treated by stereotactic radiosurgery (STRS) which were totally obliterated as shown by follow-up angiography. Of these cases, seven had intracerebral aneurysms at initial angiography, two of which were multiple. Five patients had saccular aneurysms at commonly recognized sites on the circle of Willis or main proximal cerebral arteries, while two patients had aneurysms on distal AVM feeder arteries in atypical sites (one saccular, one fusiform). Saccular aneurysms at typical sites were found to be unchanged in size following AVM obliteration. The significance of this finding in the management of patients who present with subarachnoid haemorrhage and who have both aneurysms and AVMs is discussed.

Adult↗
PubMed1996

Preoperative risk stratification identifies low-risk candidates for early extubation after aortocoronary bypass grafting.

Early tracheal extubation has been the focus of recent attempts to accelerate the care of patients after aortocoronary bypass. Following the 1994 validation of a preoperative mortality risk mode based on the Society of Thoracic Surgeons National Cardiac Surgery Database, we examined the records of 328 aortocoronary bypass patients from our institution and identified 133 patients with low preoperative mortality risk. Their records were then analyzed for duration of tracheal intubation. One low-risk patient who did not survive was excluded from the analysis. Of the remaining 132 patients, 108 experienced no postoperative complications; nevertheless, 50 of these were intubated longer than 10 hours despite freedom from complications. In a 2nd group of 153 consecutive low-risk patients, we prospectively implemented a patient care protocol that designated low-risk patients as eligible for accelerated weaning. Compared were the 1st group, these patients with low preoperative mortality risk were weaned from mechanical ventilation in 40% less time. Thus, we found that low preoperative mortality risk predicts success in early tracheal extubation. Risk stratification appears to be a simple and useful means of identifying patients least likely to encounter postoperative complications. Risk-based accelerated recovery was successfully implemented without requiring a change in anesthetic or surgical management.

Coronary Artery Bypass↗
PubMed1995

Measuring program performance in methadone treatment using in-treatment outcomes: an illustration.

Quality measurement and quality assurance in substance abuse treatment have, over the past few years, become a major policy issue. In addition, there is interest in the degree to which client outcomes can play a role in measuring treatment program performance. This article discusses the movement toward outcome-based performance measurement in substance abuse treatment. Examples of the products that such a performance measurement system might produce are provided. Why outcomes must be case-mix adjusted is discussed. In addition, using data from 18 methadone programs and more than 2,000 methadone clients from the Treatment Outcome Prospective Study, an illustration of case-mix-adjusted performance measurement is provided.

Demography↗
PubMed1995

Regulation of ornithine decarboxylase mRNA levels in human breast cancer cells: pattern of expression and involvement of core enhancer promoter element.

Ornithine decarboxylase (ODC) expression is increased by growth factors and is obligatory for progression through the cell cycle in a wide variety of cell types. In this study, a variant human ODC cDNA was identified, sequenced, and used to probe mRNA levels in human breast tumor cell lines and xenografts. ODC mRNA was elevated about 3-fold in estrogen receptor-negative (ER-) tumors (MDA-MB-231) when compared with ER-positive (ER+) tumors (MCF-7), as assessed by quantitative autoradiographic analysis of in situ hybridization experiments. The pattern of ODC mRNA in MDA-MB-231 (ER-) xenografts was polarized to the extreme periphery of the tumor, whereas the distribution of ODC mRNA was more evenly distributed in MCF-7 (ER+) xenografts. This correlates with hematoxylin and eosin staining patterns, suggesting that ER+ and ER- xenografts have a differential dependence on host vasculature for growth factor supply. ODC mRNA was elevated 5-fold in MDA-MB-231 cells versus MCF-7 cells when analyzed in cell culture. These relative mRNA levels correlate with increased levels of "core" enhancer binding nuclear proteins in MDA-MB-231 cells over that detected in MCF-7 cells.

Animals↗
PubMed1994

Presynaptic modulation by eicosanoids in cortical synaptosomes.

In continuing experiments to determine the ionic basis of inhibitory presynaptic modulation, rat cortical synaptosomes were employed and receptor-activated K+ efflux was determined with a K+ sensitive electrode. When synaptosomes were sub-optimally depolarized by veratridine, the addition of agents that activated purinergic, alpha 2-adrenergic, muscarinic and opioid receptors all promoted K+ efflux. With 2-chloroadenosine as a model inhibitory presynaptic modulator, the increased K+ efflux evoked by this agent was blocked by the cyclooxygenase inhibitor indomethacin suggesting that arachidonic acid or its metabolites was an intermediary in opening the channel. When arachidonic acid and PGE2 were tested, both promoted K+ efflux that was inhibited by dendrotoxin and mast cell degranulating peptide, two agents that are known to inhibit a delayed rectifier K+ current. Our results suggest that via eicosanoid second messengers, inhibitory presynaptic modulators open a sub-class of K channels that hyperpolarize nerve terminals, therefore less Ca2+ would enter per nerve impulse and thus the evoked release of neurotransmitters would be decreased.

Animals↗