Search PubMed⌕ Search

Biomedical subjects

C J Cooper

Publications and source records attributed to C J Cooper.

At least 19 recordsLinked to original sources
PubMed2001

Efficacy of postdeployment balloon dilatation for current generation stents as assessed by intravascular ultrasound.

Adjunctive balloon dilatation strategy has been shown to improve optimal stent deployment. As improvements in current stent designs evolve, less adjunctive balloon dilatation may be needed. However, few data currently exist to support this practice. We evaluated 88 native coronary lesions treated with single stent implantation (Nir, Tristar or S670). Serial intravascular ultrasound was performed after successful stent deployment and again after adjunctive balloon dilatation. To investigate further the precise expansion characteristics of the stents, serial volumetric intravascular ultrasound analyses were performed in 40 patients with automated pullback. After adjunctive balloon dilatation, minimal stent area increased significantly, from 6.4 +/- 2.1 to 7.4 +/- 2.2 mm(2) (p <0.001). Volumetric analysis showed a corresponding increase in stent volume index (6.6 +/- 1.8 to 7.5 +/- 2.0 mm(3)/mm, p <0.001). In the analysis of cross sections at 0.5-mm axial intervals, the percentage of cross sections, where stent area was > or =80% of the average reference lumen area, increased from 51% to 78% (p <0.001). Similarly, the percentage of cross sections, where stent area was > or =90% of the average reference lumen area, increased from 29% to 56% (p <0.001) with postdilatation. Postdeployment high- pressure balloon dilatation improved minimal stent area and volumetric expansion throughout the stented segment.

Angioplasty, Balloon, Coronary↗
PubMed2000

Renal artery angioplasty and stent placement: predictors of a favorable outcome.

BACKGROUND: Renal artery stenosis is a common disorder and is an established cause of hypertension and renal insufficiency. Although treatment with renal artery stents has been shown to improve blood pressure and renal function for some patients, the patient population most likely to benefit is unknown. The current study was designed to determine which factors are predictive of improved blood pressure and renal function when patients with renal artery stenosis are treated with renal artery angioplasty and stent placement. METHODS: In a prospective evaluation 127 consecutively enrolled patients with renal artery stenosis in 171 vessels were treated with angioplasty and intravascular stents. Blood pressure and serum creatinine concentration were measured before stent placement and during the follow-up period. RESULTS: The mean length of the follow-up period was 15 +/- 14 months. Mean systolic blood pressure improved among patients with hypertension (from 177 +/- 26 mm Hg before stent placement to 151 +/- 24 mm Hg 6 months after stent placement (P <.001). The greatest improvement occurred among those with the highest baseline systolic blood pressure. This beneficial effect on blood pressure was sustained for 3 years. Sex, age, diastolic blood pressure, number of vessels into which stents were placed, serum creatinine concentration, presence of bilateral disease, race, and severity of stenosis were not predictive of improved blood pressure. Mean creatinine concentration was not significantly changed for the group as a whole. A significant decrease in serum creatinine concentration occurred among 43% of patients with baseline renal insufficiency. None of the examined variables was predictive of improvement. CONCLUSIONS: Renal artery angioplasty and stent placement produced a significantly greater reduction in systolic blood pressure among patients with the highest baseline systolic blood pressure. Other examined variables were not predictive of a significant improvement in blood pressure. No examined variable was predictive of improved renal function. We concluded that management of renal artery stenosis with renal artery angioplasty and stent placement is most likely to result in significant improvement in systolic blood pressure among patients with the highest baseline systolic blood pressure.

Aged↗
PubMed2000

Interferon gamma induction during oral tolerance reduces T-cell migration to sites of inflammation.

BACKGROUND & AIMS: Previous data suggest that oral antigen induces interferon (IFN)-gamma production in intestinal T cells. However, oral tolerance is associated with decreased production of IFN-gamma by T cells after antigen sensitization. The aim of this study was to examine the role of IFN-gamma in oral tolerance. METHODS: Oral tolerance was examined in BALB/c mice after the adoptive transfer of T cells from chicken ovalbumin (OVA(323-339))-specific, DO11.10 x RAG-1(-/-) T-cell receptor transgenic mice. RESULTS: OVA feeding induced systemic tolerance of delayed-type hypersensitivity (DTH) and antibody responses. OVA feeding up-regulated IFN-gamma production by transgenic T cells in Peyer's patch and mesenteric lymph node but not splenic tissues. Treatment of OVA-fed mice with neutralizing monoclonal antibody to IFN-gamma prevented tolerance of DTH responses. Analysis of transgenic T-cell numbers in DTH sites by immunohistochemical staining suggested that induction of IFN-gamma by oral antigen decreased accumulation of transgenic T cells in cutaneous sites of antigen injection. IFN-gamma-deficient or wild-type DO11.10 and BALB/c mice were used to show that IFN-gamma production by donor transgenic T cells was critical for oral tolerance. CONCLUSIONS: These data suggest that the induction of IFN-gamma by oral antigen contributes to systemic tolerance by decreasing migration of T cells to peripheral sites of inflammation.

Administration, Oral↗
PubMed2000

8 french transradial coronary interventions: clinical outcome and late effects on the radial artery and hand function.

BACKGROUND: Limited information is available on the effects of 8 French (Fr) transradial procedures on radial patency. In addition, the effects of radial procedures and radial occlusion on hand function are unknown. METHODS: Two groups were recruited: twenty-four patients who had undergone 26 transradial 8 Fr interventions and 16 patients who had undergone 16 transradial 6 Fr procedures. At 1 year, radial patency, hand strength and hand endurance were measured. RESULTS: No major adverse cardiac events or vascular complications were noted in either group. Late radial occlusion was noted in 2/18 (11%) 8 Fr patients and 3/16 (19%) 6 Fr patients (p = ns). There were no differences in the 8 Fr group between the catheterized and uncatheterized radial arteries for diameter (3.2 +/- 1.1 mm versus 3.3 +/- 0.7 mm, respectively; p = NS) or volumetric flow (55 +/- 51 ml/minute versus 57 +/- 45 ml/minute, respectively; p = NS). No differences in hand strength or hand endurance were seen between the catheterized and uncatheterized arms in the 8 Fr group, between the 8 Fr and 6 Fr groups, or between occluded and non-occluded patients. CONCLUSION: Transradial use of 8 Fr guiding catheters appears to be feasible and safe in highly selected patients, albeit associated with a low incidence of silent radial occlusion. Additionally, neither the use of 8 Fr sheaths nor the presence of radial artery occlusion appear to adversely affect hand strength or endurance.

Aged↗
PubMed1999

The differentiated state of intestinal lamina propria CD4+ T cells results in altered cytokine production, activation threshold, and costimulatory requirements.

Intestinal lamina propria (LP) CD4+ T cells are memory-like effector cells that proliferate at relatively low levels and require high levels of TCR signaling and costimulation for full activation in vitro. To study LP CD4+ T cell functional potential we used DO11.10 TCR transgenic (Tg) mice specific for the class II MHC-restricted OVA323-339 peptide and nontransgenic BALB/c mice. Activation of LP Tg+ T cells with Ag using mucosal explants induced high levels of IL-2, IL-4, and IFN-gamma. Culturing isolated LP cells with IL-12 enhanced IFN-gamma production and down-regulated IL-4 and IL-2, whereas addition of IL-4 maintained IL-4 production without inhibiting IFN-gamma production. Systemic administration of relatively high dose (HD; 100 nM) OVA323-339 peptide induced similar levels of bromodeoxyuridine (BrdU) incorporation by LP and splenic Tg+ T cells in vivo, whereas low dose (LD; 4.5 nM) peptide injections induced 4-fold greater levels of BrdU incorporation for LP compared with splenic Tg+ T cells. Coadministration of CTLA-4Ig reduced BrdU incorporation for splenic cells by 70% with HD and LD stimulation, but had little effect on LP responses to HD stimulation. Results of in vivo studies were confirmed in nontransgenic BALB/c mice using HD (200 microg) and LD (10 microg) anti-CD3 mAb+/- CTLA-4Ig. These results suggest that LP T cells are differentiated effector cells that respond at high levels when activated with relatively low levels of Ag- and B7-mediated costimulation in vivo. The reduced activation threshold of LP T cells may facilitate responses to low levels of Ag derived from mucosal pathogens.

Animals↗
PubMed1999

Effect of transradial access on quality of life and cost of cardiac catheterization: A randomized comparison.

BACKGROUND: Transradial access is a recently developed alternative for diagnostic cardiac catheterization. Its effects on quality of life after the procedure, patient preference, and cost are unknown. METHODS AND RESULTS: We performed a randomized single-center trial in which 99 patients underwent transfemoral and 101 underwent transradial diagnostic cardiac catheterization. Quality of life was measured with the SF-36 and visual analog scales at baseline, 1 day, and 1 week. Patients were examined at 1 day and at 1 week after for complications. Costs were measured prospectively. One patient in the femoral group and 2 in the radial group crossed over to the alternative access site. There were no major access site complications. One patient in the transfemoral group had a minor stroke. Transradial catheterization significantly reduced median length of stay (3.6 vs 10.4 hours, P <.0001). Over the first day after the procedure, measures of bodily pain, back pain, and walking ability favored the transradial group (P <.05 for all comparisons). Over the week after the procedure, changes in role limitations caused by physical health, bodily pain, and back pain favored the transradial group (P <.05 for all comparisons). There was a strong patient preference for transradial catheterization as well (P <. 0001). Transradial catheterization led to significant reductions in bed, pharmacy, and total hospital costs ($2010 vs $2299, P <.0001). CONCLUSIONS: Among patients undergoing diagnostic cardiac catheterization, transradial access leads to improved quality of life after the procedure, is strongly preferred by patients, and reduces hospital costs.

Cardiac Catheterization↗
PubMed1998

The influence of basal nitric oxide activity on pulmonary vascular resistance in patients with congestive heart failure.

Increased pulmonary resistance may reduce survival and treatment options in patients with congestive heart failure. Nitric oxide (NO) is a determinant of normal pulmonary resistance vessel tone. We tested the hypothesis that loss of NO function contributes to increased pulmonary vascular resistance index (PVRI) in congestive heart failure. Pulmonary arterial resistance vessel function was studied in 25 conscious adults. Three groups were studied: 8 controls, 9 patients with congestive heart failure and normal PVRI, and 8 patients with congestive heart failure and raised PVRI. Segmental arterial flow was determined with a Doppler wire and quantitative angiography. NG-monomethyl-L-arginine (L-NMMA) was used to inhibit NO, whereas phenylephrine was used as an endothelium-independent control. The response to inhibition of NO with L-NMMA was less in patients with congestive heart failure and elevated PVRI than in patients with congestive heart failure and normal PVRI (p <0.05). The difference in response between the congestive heart failure groups was specific to NO-dependent regulation because the response to the endothelium-independent constrictor phenylephrine was not different (p = 0.92). There was no difference in response to L-NMMA between controls and patients with congestive heart failure and normal PVRI. The response to L-NMMA correlated to PVRI. In adults with congestive heart failure, NO appears to play an important role in maintaining normal pulmonary resistance.

Adolescent↗
PubMed1997

U.S. experience of transradial coronary stenting utilizing Palmaz-Schatz stents.

Transradial coronary stenting has been associated with a low frequency of vascular complications and shortened hospital length of stay, but few reports of safety and feasibility are available. To determine the safety and efficacy of transradial coronary stenting, our initial experience in 38 patients was reviewed. Palmaz-Schatz stents hand-mounted on Predator (Cordis Corp., Miami Lakes, FL) balloons were delivered through 6 Fr guide catheters. In 1 of 38 patients (3%) radial access could not be achieved. Fifty-five stents were implanted in 44 lesions (3 total occlusion, 18 type A, 19 type B, 9 type C, National Heart Lung Blood Institute Classification). Access time was 7.7 +/- 4.6 min. Procedural success was achieved in 36 patients (97%). In one patient, a stent could not be delivered to a distal circumflex lesion due to marked proximal tortuosity and calcification. Poststenting residual stenosis was 0 +/0 10%. No access-related complications occurred. One patient had stent thrombosis and required repeat angioplasty and stenting. We conclude that transradial coronary stenting is both feasible and safe with a low risk of access complications and with excellent procedural results.

Adult↗
PubMed1997

Intraaortic balloon pump insertion after percutaneous revascularization in patients with severe peripheral vascular disease.

Severe aortoiliac peripheral vascular disease (PVD) is considered a contraindication for the placement of an intraaortic balloon pump (IABP) because of a high risk of limb ischemia. Recent advances in percutaneous transluminal angioplasty (PTA) and stenting have altered the treatment of iliac stenoses such that the results of PTA with stenting compare favorably with surgery. We reviewed our experience with placement of IABP between July 1994 and February 1996. Of 64 patients receiving IABP, 17 had known or suspected peripheral vascular disease. Severe iliac or distal aortic stenoses were present in 9. These 9 patients underwent PTA with or without stenting prior to 10 IABP insertions. Limb ischemia occurred in 10% of PVD patients treated with percutaneous revascularization, compared to 11% in patients without PVD. No patient had a serious vascular complication or required vascular surgery. We conclude that percutaneous revascularization in patients with severe aortoiliac PVD, for whom this IABP insertion had previously been considered contraindicated, results in a low rate of limb ischemia.

Aged↗
PubMed1997

The string measure of the ERP: what does it measure?

The event-related brain potential (ERP) has been investigated extensively inan effort to understand the neurophysiological bases of intelligence. Measures derived from the ERP have been used as indices of intelligence, particularly the string measure of the complexity of the ERP. However, the string measure has been criticised for being non-specific and for being dependent on ERP amplitude. These criticisms were tested by investigating relationships between ERP string measure, ERP amplitude measures, and the ERP power spectrum. It was found that the string measure was non-specific in that it indexes both low and high frequency event-related activity; the string measure is also dependent on ERP amplitude. The string measure is therefore not a valid measure of the ERP. It was concluded that the string measure should be abandoned; human intelligence cannot map in a simple way onto gross measures of scalp-recorded electrocortical activity.

Adult↗
PubMed1997

Outcome-based management of retinopathy of prematurity. Multicenter Trial of Cryotherapy for Retinopathy of prematurity Cooperative Group.

PURPOSE: A system is presented for sequentially computing the risk of progression of retinopathy of prematurity (ROP) for infants born weighing not more than 1250 gm. A personal computer program is used to monitor infants' risk of threshold ROP from first appearance of ROP, and the progression in severity is tracked with multiple logistic risk models developed from data in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity. METHODS: After entry of the infant's birth weight, gestational age, ethnicity, birth in the current hospital or elsewhere, single or multiple birth, and maturity zone of retinal vessels, risk of progression to threshold severity is calculated. New estimates of risk are computed at onset of ROP and prethreshold ROP (any zone I ROP, zone II stage 2+ or 3) according to the extent of retinal vascularization when ROP first appears, how rapidly ROP progresses, and how severe it is. When threshold ROP (8 total or 5 contiguous clock hours of stage 3+ in zone I or II) is reached,the system provides separate estimates of risk that the eye will have an unfavorable 3-month outcome if treated or not. RESULTS: Estimates of risk of progression to threshold disease among the 4099 patients in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity natural history study varied from less than 1% to more than 70%. For eyes with threshold disease, the risk of an unfavorable outcome at 3 months without treatment varied from less than 10% to more than 90%. CONCLUSION: This method of tracking identifies infants at high risk for severe ROP and poor structural outcome. It provides information about prognosis with a specificity heretofore impossible.

Algorithms↗
PubMed1996

Role of nitric oxide in the local regulation of pulmonary vascular resistance in humans.

BACKGROUND: Endothelium-derived nitric oxide (NO) may be an important mediator of vascular resistance in the pulmonary circulation. We tested the hypotheses that in conscious adults the endothelium, through NO production, is important in maintaining basal pulmonary vascular resistance and that it can increase NO production further in response to receptor-mediated stimulation, leading to further vasodilation. METHODS AND RESULTS: Pulmonary arterial resistance vessel function was studied within the distribution of a segmental lower lobe pulmonary artery in eight conscious adults 37 to 76 years old who were undergoing cardiac catheterization. Segmental blood flow was determined with use of a Doppler-tip guide wire and quantitative angiography. Drugs were administered locally within the segmental artery through an infusion catheter. NG-Monomethyl-L-arginine (L-NMMA) was used as a specific inhibitor of NO production, whereas acetylcholine (ACh) was used to test receptor-mediated vasodilation. To demonstrate that vasodilation to ACh was NO dependent, ACh response was tested alone, in the presence of L-NMMA, and in the presence of a control constrictor phenylephrine. Basal pulmonary vascular resistance was NO dependent because L-NMMA infusion resulted in a dose-dependent decrease in local flow velocity (P < .005), with flow decreasing 33% at the highest dose of L-NMMA. ACh infusion resulted in a dose-dependent increase in flow velocity (P = .001). The ACh response was at least in part NO dependent because it was diminished by the presence of L-NMMA (P < .05). The effect of L-NMMA on the ACh response was not due to nonspecific preconstriction because L-NMMA diminished the ACh response significantly more than did the endothelium-independent constrictor phenylephrine (P < .05) despite comparable preconstriction. CONCLUSIONS: In healthy conscious adults, (1) normal basal pulmonary resistance is maintained in part by continuous local production of NO and (2) the local NO production is responsive to receptor-mediated stimulation, leading to further vasodilation, and can be tested with ACh.

Acetylcholine↗
PubMed1996

A high prevalence of abnormal personality traits in chronic users of anabolic-androgenic steroids.

OBJECTIVE: (1) To assess the personality profiles of the anabolic androgenic steroid users (AAS) and (2) to determine whether valid premorbid personality traits could be obtained from cross sectional assessment using multisource data. METHODS: The first author became a participant-observer in a group of body builders. An experimental group of body builders who had been using AAS for no more than 18 months (n = 12) was identified. A group of control subjects, each of whom claimed that he did not, and never had, used AAS (n = 12) was also recruited during this period. Key informants played a crucial role in recruiting subjects representative of the AAS and body building communities. An interview schedule based on the Diagnostic and statistical manual of mental disorders (DSM3-R) personality disorder criteria was conducted with each subject. Additional data were obtained from an AAS using informant and significant others including family and friends. RESULTS: The user group was significantly heavier than the control group and showed abnormal personality traits, in contrast to the control group. Personality traits of AAS users before the onset of AAS use, assessed retrospectively, were not different from personality traits of control subjects. There were significant differences between the before and after personality traits in AAS user group. CONCLUSIONS: The results suggest (1) that AAS use is associated with significant disturbances in personality profile, and (2) that these personality disturbances are possibly the direct result of AAS use.

Adolescent↗
PubMed1995

Helical CT: practical considerations and potential pitfalls.

Helical (spiral) computed tomography (CT) is having a dramatic impact on body imaging. Unlike conventional CT, helical CT provides continued volumetric acquisition as the patient moves through the gantry. Advantages of helical CT include dramatically shortened examination times, improved visibility of vascular structures, better enhancement of parenchymal organs, the capability for retrospective imaging and three-dimensional (3D) vascular studies, and potential reduction in use of contrast material. However, helical CT requires one to be more cognizant of the relationship between contrast material administration and scanning, since the optimal temporal window for detection of disease can be missed. Factors unique to helical technology can produce artifacts, which one must be aware of when interpreting helically generated scans. Many of these artifacts relate to accentuation of vascular or parenchymal enhancement. Others occur during production of high-quality 3D images. Additional artifacts are sure to be identified with increased experience with helical CT.

Aortic Dissection↗
PubMed1995

Nodular sarcoidosis of the liver and spleen: analysis of 32 cases.

PURPOSE: To describe the computed tomographic (CT) appearance of nodular hepatosplenic sarcoidosis and its association with stage with chest radiography and clinical status. MATERIALS AND METHODS: Thirty-two patients (21 women, 11 men; aged 25-68 years) with nodular hepatosplenic sarcoidosis were evaluated. CT findings were described along with chest radiographic stage, clinical status, and level of angiotensin-converting enzyme (ACE). RESULTS: Nodules were small, multiple, and of low attenuation. Organomegaly was common. Abdominal adenopathy was present in 76% of the patients. Chest radiographs were normal in 25%; 61% had stage 1 or 2 radiographs. Abdominal or systemic symptoms were present in 66%. ACE level was elevated in 10 (91%) of 11 patients tested. No change in chest radiographic stage was noted in 74% of patients with follow-up radiographs. CONCLUSION: Nodular hepatosplenic sarcoidosis is associated with organomegaly, adenopathy, and symptoms. Nodules were not associated with advanced lung disease and did not herald a change in chest radiographic stage. An elevated ACE level may be helpful in diagnosis.

Adult↗