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Biomedical subjects

S D Ross

Publications and source records attributed to S D Ross.

At least 37 records · Page 2Linked to original sources
PubMed1999

Spinal cord protection during aortic cross-clamping using retrograde venous perfusion.

BACKGROUND: Paraplegia remains a devastating complication following thoracic aortic operation. We hypothesized that retrograde perfusion of the spinal cord with a hypothermic, adenosine-enhanced solution would provide protection during periods of ischemia due to temporary aortic occlusion. METHODS: In a rabbit model, a 45-minute period of spinal cord ischemia was produced by clamping the abdominal aorta and vena cava just below the left renal vessels and at their bifurcations. Four groups (n = 8/group) were studied: control, warm saline, cold saline, and cold saline with adenosine infusion. In the experimental groups, saline or saline plus adenosine was infused into the isolated cavae throughout the ischemic period. Clamps were removed and the animals to recovered for 24 hours before blinded neurological evaluation. RESULTS: Tarlov scores (0 = paraplegia, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop) were (mean +/- standard error of the mean): control, 0.50 +/- 0.50; warm saline, 1.63 +/- 0.56; cold saline, 3.38 +/- 0.26; and cold saline plus adenosine, 4.25 +/- 0.16 (analysis of variance for all four groups, p < 0.00001). Post-hoc contrast analysis showed that cold saline plus adenosine was superior to the other three groups (p < 0.0001). CONCLUSION: Retrograde venous perfusion of the spinal cord with hypothermic saline and adenosine provides functional protection against surgical ischemia and reperfusion.

Animals↗
PubMed1999

Preservation of intercostal arteries during thoracoabdominal aortic aneurysm surgery: a retrospective study.

OBJECTIVE: The purpose of this article was to examine the influence of reimplantation of patent intercostal and lumbar arteries on the incidence of postoperative paraplegia/paraparesis in patients undergoing clamp-and-sew surgical repair of thoracoabdominal aortic aneurysms. METHODS: Data from January 1987 through December 1997 were retrospectively collected on 132 patients. Ninety-one patients in group I underwent aneurysm repairs before January 1995 and did not undergo intercostal artery reimplantation. Group II included the more recent 41 patients who had vessels between the eighth thoracic intercostal and the second lumbar arteries reimplanted to the graft or preserved at the aortic anastomoses. RESULTS: The operative mortality rate was 13.2% (12/91) in group I and 4.9% (2/41) in group II (P =.22). The incidence of postoperative paraplegia was significantly lower in the more recent cohort of patients (8.8% [8/91] in group I vs 0% [0/41] in group II, P =.05). The overall rate of spinal cord dysfunction was lowered from 9.9% (9/91) in group I to 2.4% (1/41) in group II (P =.17). However, a multivariable logistic regression analysis identified only aneurysm extent (Crawford type I and type II) as a predictor of less postoperative spinal cord injury (P =.08). The average aortic crossclamp time in group I was 30.3 +/- 11.5 (SD) minutes, and the time of aortic occlusion in group II was not significantly prolonged, with an average crossclamp time of 31.0 +/- 21.0 (SD) minutes (P =. 88). CONCLUSIONS: An aggressive approach to maintain intercostal artery patency during clamp-and-sew repair of thoracoabdominal aortic aneurysms may effectively lower the incidence of spinal cord injury without prolonging aortic crossclamp time.

Aged↗
PubMed1999

Selective adenosine-A2A activation reduces lung reperfusion injury following transplantation.

BACKGROUND: The adenosine-A2A receptor on the neutrophil is responsible for several anti-inflammatory actions. We hypothesized that DWH-146e, a selective adenosine-A2A agonist, would reduce lung reperfusion injury following transplantation. METHODS: We used an isolated, whole blood-perfused, ventilated rabbit lung model. Donor rabbits underwent lung harvest after pulmonary arterial PGE1 injection and Euro-Collins preservation solution flush, and lungs were preserved for 18 hours at 4 degrees C. Group I lungs (n = 9) served as control subjects. Group II lungs (n = 9) were reperfused with whole blood that was first passed through a leukocyte-depleting filter. In group III (n = 9), DWH-146e was added to the blood reperfusate (25 microg/kg) immediately before reperfusion and was administered throughout the reperfusion period (1 microg/kg/min). All lungs were reperfused for 30 minutes. RESULTS: Arterial oxygenation in group II and group III was significantly higher than that of group I after 30 minutes of reperfusion (514.27 +/- 35.80 and 461.12 +/- 43.77 vs 91.41 +/- 20.58 mm Hg, p < .001). Pulmonary vascular resistance was significantly reduced in group III (22,783 +/- 357 dynes x s x cm(-5)) compared to both group II and group I (31,057 +/- 1743 and 36,911 +/- 2173 dynes x s x cm(-5), p < .001). Airway compliance was improved in groups II and III when compared to group I (1.68 +/- 0.08 and 1.68 +/- 0.05 vs 1.36 +/- 0.13, p = .03). Microvascular permeability in group III was reduced to 106.82 +/- 17.09 compared with 165.70 +/- 21.83 ng Evans blue dye per gram of tissue in group I (p = .05). Group III myeloperoxidase activity was 39.88 +/- 4.87 compared with 88.70 +/- 18.69 deltaOD/g/min in group I (p = .03); group II myeloperoxidase activity was 56.06 +/- 7.46. CONCLUSIONS: DWH-146e reduced lung neutrophil sequestration and dramatically improved pulmonary graft function. Neutrophils are important components of the inflammatory cascade of reperfusion injury and their source may include both the circulating blood and the lung graft itself. Selective adenosine-A2A activation interrupts the neutrophil-mediated inflammatory response and reduces lung reperfusion injury following transplantation.

Adenosine↗
PubMed1999

Maximum androgen-blockade with medical or surgical castration in advanced prostate cancer: A meta-analysis of nine published randomized controlled trials and 4128 patients using flutamide.

With the recent Southwest Oncology Group (SWOG) publication of their metastatic prostate cancer clinical trial results, which concluded that orchiectomy and flutamide as maximal androgen blockade (MAB) therapy vs orchiectomy alone does not significantly improve survival (NCI 0105), and the 1989 publication from the same cooperative group indicating a 24% improvement in survival for MAB therapy with leuprolide and flutamide versus leuprolide alone (NCI 0036), clinicians may well be undecided about the likelihood of clinical benefits with flutamide in combination with medical or surgical castration. To better characterize this important therapeutic decision, we assessed the survival benefit of MAB therapy with flutamide through a meta-analysis of up-to-date information from studies reported/conducted from 1989 through 1998. All peer-reviewed published randomized controlled trials comparing treatment with flutamide plus either lutenizing hormone releasing hormone (LhRH) agonists or orchiectomy as MAB treatment with LhRH or orchiectomy alone were included. The primary objective of the study was to form a combined estimate and confidence interval for the hazard ratio (as measured by the relative risk (RR) of survival in a comparison of castration vs MAB) summarizing the effect of flutamide treatment on overall survival. Directly extracted estimates of the log hazard ratio were used if available (1 study); if not, either an estimate of the RR based on a reported P-value from a log rank test (7 studies) or a discrete proportional hazards approximation based on reconstructed annual life tables for the treatment arms (1 study) were used. Nine studies with 4128 patients with advanced prostate cancer were included in these analyses. Pooled estimates demonstrated a 10% improvement in overall survival with flutamide as MAB therapy (relative risk (RR)=0.90, 95% Confidence Interval=0.79, 1.00). The currently available updated evidence from randomized trials shows a 10% benefit in overall survival with flutamide as MAB therapy in comparison to conventional castration, almost identical to the estimate reported in the recently published Southwest Oncology Group Study (NCI 0105).

Journal Article↗
PubMed1999

Omeprazole plus antibiotics in the eradication of Helicobacter pylori infection: a meta-regression analysis of randomized, controlled trials.

This article presents a meta-regression analysis of published studies of omeprazole plus antibiotics (amoxicillin, clarithromycin, or an imidazole derivative) in the treatment of Helicobacter pylori. Eligible studies were all randomized, controlled trials published through April 1996 with 10 or more patients receiving omeprazole plus antibiotics for 5 or more days and testing for H. pylori eradication 4 weeks or more after treatment. Probability of eradication was calculated for each treatment arm, and logistic regression was performed using study characteristics as covariates. Seventy-four studies involving 117 treatment arms with 4,769 patients were identified. The eradication rate was 76% for omeprazole plus clarithromycin and 65% for omeprazole plus amoxicillin dual regimens (P <.0001). Eradication rates for triple regimens were 82%, omeprazole plus amoxicillin plus clarithromycin; 83%, omeprazole plus amoxicillin plus imidazole; and 89%, omeprazole plus clarithromycin plus imidazole. In a multiple logistic regression analysis, significant factors were antibiotic, disease, omeprazole dose, and whether treatment was followed by maintenance omeprazole. A systematic overview of the best available evidence suggests that dual therapy with omeprazole plus clarithromycin is superior to omeprazole plus amoxicillin. Triple therapy is better than dual therapy. Treatment works better on ulcers than on nonulcer dyspepsia. Higher doses of omeprazole give better results. Additional trials exploring higher omeprazole doses for varying durations as well as cost, side effects, and compliance trade-offs with efficacy are recommended.

Anti-Bacterial Agents↗
PubMed1999

Safety of nifedipine in angina pectoris: a meta-analysis.

-Our objective was to compare cardiovascular event rates in patients with stable angina receiving nifedipine as monotherapy or combination therapy and in active drug controls. A MEDLARS search of published articles from 1966 to 1995 in English, French, German, Italian, or Spanish, supplemented by a manual search of bibliographies, identified 60 randomized controlled trials that met protocol criteria. Blinded articles were extracted by 2 physicians. The pooled risks of death, withdrawal, and cardiovascular event were computed and expressed as odds ratios (ORs) for all nifedipine formulations and relative to same study control drug regimens. Thirty cardiovascular events were reported in 2635 nifedipine exposures (1.14%) and 19 events in 2655 other active drug exposures (0.72%). Unadjusted ORs for nifedipine versus controls were 1.40 (95% CI, 0.56 to 3.49) for major events (death, nonfatal myocardial infarction, stroke, revascularization procedure), 1.75 (95% CI, 0.83 to 3.67) for increased angina, and 1.61 (95% CI, 0.91 to 2.87) for all events (major events plus increased angina). Episodes of increased angina were more frequent on immediate-release nifedipine (OR, 4.19 [95% CI, 1.41 to 12.49]) and on nifedipine monotherapy (OR, 2.61 [95% CI, 1.30 to 5.26]). The OR for immediate-release nifedipine was significantly higher than that for sustained-release/extended-release nifedipine (P=0.001), and the OR for nifedipine monotherapy was higher than that for nifedipine combination therapy (P=0.03). Increased risks of cardiovascular events in patients with stable angina on nifedipine were due primarily to more episodes of increased angina, confined to the immediate-release formulation and to nifedipine monotherapy.

Adrenergic beta-Antagonists↗
PubMed1999

American Orthopaedic Foot and Ankle Society shoe survey of diabetic patients.

A one-page written survey was completed by 402 randomly selected patients with diabetes in five cities during a scheduled visit to their endocrinologist. Patients averaged 61.5 years of age and had been diagnosed with diabetes for 27.3 years. This study suggests that approximately 25% of adults with diabetes are at risk for developing foot ulcers, the precursor to deep infection leading to lower limb amputation. The goal at the inception of this project was to obtain benchmark data on the current level of prophylactic foot care being provided to adult patients with diabetes. The results of this survey suggest that most individuals with diabetes and their physicians are aware of potential diabetic foot morbidity, yet very few take advantage of prophylactic protective footware. Even fewer are presently taking advantage of benefits established through the Medicare Therapeutic Foot Bill. This survey highlights a substantial opportunity for improvement in the long-term care of individuals with diabetes.

Adolescent↗
PubMed1997

Maximum androgen blockade in advanced prostate cancer: a meta-analysis of published randomized controlled trials using nonsteroidal antiandrogens.

OBJECTIVES: To assess the survival benefit of maximum androgen blockade (MAB) using nonsteroidal antiandrogens (NSAAs) through meta-analysis of published randomized controlled trials (RCTs). METHODS: All RCTs comparing treatment with NSAA plus either luteinizing hormone-releasing hormone (LHRH) or orchiectomy versus treatment with LHRH or orchiectomy alone were included if the necessary statistical summaries were present in the publication. Estimates and standard errors of log hazard ratio for overall survival and progression-free survival were derived from published studies using two methods: (1) reconstructing an annual life table from graphical presentations of survival distributions and fitting discrete proportional hazard models, and (2) reconstructing the log hazard ratio from reported P values and numbers of deaths. An alternative set of log hazard ratios was derived from figures presented in a summary report by the Prostate Cancer Trialists' Collaborative Group (PCTCG). Comparative meta-analyses were performed using the random effects approach of DerSimonian and Laird. Additionally, published studies were used in a random-effects-based meta-analysis of objective tumor response. RESULTS: Nine studies provided enough information to perform a meta-analysis for survival using one of the two methods. Estimates of relative risks (RR) comparing treatment with NSAA plus either LHRH or orchiectomy versus treatment with LHRH or orchiectomy alone with respect to overall survival were 0.78 (95% confidence intervals [CIs] 0.67 to 0.90) using method 1, and 0.84 (95% CI 0.76 to 0.93) using method 2. Sensitivity analyses based on PCTCG data showed that a favorable survival result for MAB was associated with NSAAs but not with steroidal antiandrogens and depended on randomization blinding and overall trial quality. Additionally, random-effects-based meta-analysis of published studies showed a significant increase in time-to-progression (RR = 0.74; 95% CI 0.63 to 0.86) and an increase in objective tumor responses for MAB using NSAAs compared with castration alone (odds ratio = 0.65; 95% CI 0.51 to 0.81; P = 0.00022). CONCLUSIONS: Inconsistent results have been published about the benefit of MAB in advanced prostate cancer. This meta-analysis supports a beneficial effect for MAB using NSAAs compared with castration alone, and sensitivity analyses suggest that the design of future trials should carefully address issues of patient characterization, randomization blinding, and other study quality issues.

Androgen Antagonists↗
PubMed1997

Risk of serious adverse events in hypertensive patients receiving isradipine: a meta-analysis.

A meta-analysis was performed to compare the risk of serious adverse events associated with the use of all formulations of isradipine, when used as monotherapy in hypertension, to active drug or placebo controls. Eligible studies totalled 65 published and unpublished randomised controlled trials involving 9903 subjects and 10,675 treatment exposures: 4492 to isradipine, 1473 to isradipine sustained release, 2768 to other active drugs, and 1942 to placebo. Mortality, cardiovascular outcomes, other serious incident illnesses, such as cancer, and withdrawals were sought. Seventy-five per cent of the isradipine exposures were to standard-release formulations and 25% were to sustained-release formulations. Overall, isradipine therapy shows no difference in risk of major adverse events or withdrawals compared to other active controls or placebo (odds ratios [OR] 0.9; 95% CI 0.7-1.46 and 0.5; 95% CI 0.2-1.3). These major adverse events included angina, fatal and non-fatal myocardial infarction, stroke and overall mortality. Isradipine sustained release could be compared only to placebo, based on available data, and shows a lower risk of withdrawals (OR 0.5; 95% CI 0.3-0.9), and a similar trend was observed for major adverse events, (OR 0.8; 95% CI 0.3-2.5). Published and unpublished randomised controlled trials were analysed in separate meta-analyses and later combined when this sensitivity analysis of risk showed no differences between the groups. In conclusion, we find no evidence for increased risk of serious adverse events in patients receiving isradipine as monotherapy for hypertension.

Antihypertensive Agents↗
PubMed1997

Safety of nifedipine in patients with hypertension: a meta-analysis.

Our objective was to compare cardiovascular event rates in patients with mild or moderate hypertension who received nifedipine with active drug controls. We performed a MEDLARS search using the MeSH heading "hypertension" and the text word "nifedipine" to identify all articles that were published between 1966 and August 1995 in English, French, German, Italian, and Spanish languages and that involved human subjects. The computerized search was supplemented by a manual search of article bibliographies. Review of 1880 citations revealed 98 randomized controlled clinical trials that met protocol criteria. Articles were extracted independently by two doctors who were blinded for author, institution, and treatment regimen, using a structured, pretested extraction form. Differences of opinion were resolved by consensus. Fourteen events occurred in 5198 exposures (0.27%) to nifedipine and 24 events in 5402 exposures (0.44%) to other active drug controls. Unadjusted odds ratios for nifedipine versus controls were 0.49 (95% confidence interval [CI], 0.22-1.09) for definitive events (death, nonfatal myocardial infarction or stroke, revascularization procedure) and 0.61 (95% CI, 0.31-1.17) for all events (definitive plus increased angina). The odds ratio for nifedipine monotherapy (sustained- or extended-release in 91% of exposures) was nonsignificantly higher for definitive and all events (odds ratio, 1.40; 95% CI, 0.49-4.03 and odds ratio, 1.39; 95% CI, 0.59-3.32, respectively). The odds ratio for nifedipine in combination with another drug was significantly lower for definitive and all events (odds ratio, 0.09; 95% CI, 0.01-0.66 and odds ratio, 0.15; 95% CI, 0.03-0.65, respectively). Differences in odds ratio for nifedipine monotherapy and combined therapy were statistically significant (P=.02 for definitive events and P=.001 for all events). Results support the safety of sustained- and extended-release nifedipine in the treatment of mild or moderate hypertension when it is used in combination with other drugs.

Adrenergic beta-Antagonists↗
PubMed1996

Searching for signals: mortality and cardiovascular events in published randomized control trials of nifedipine in ischemic heart disease and hypertension.

UNLABELLED: META-ANALYSIS: A meta-analysis of published randomized control trials of nifedipine in hypertension and stable angina pectoris was performed. RESULTS: The results suggest a formulation-dependent increased risk of mortality and adverse cardiovascular outcomes for monotherapy use in patients with stable angina pectoris. No increased risk was seen in the hypertension studies.

Humans↗
PubMed1995

(-)-nicotine protects against systemic kainic acid-induced excitotoxic effects.

(-)-Nicotine was shown to produce in vivo protection against neurobehavioral effects caused by systemically administered kainic acid (KA), an excitotoxin that has been widely used to induce temporal lobe convulsions including "wet dog shakes" in experimental animals. Rats pretreated with (-)-nicotine (0.5 mg/kg sc) 15 min before receiving KA (12.0 mg/kg sc) exhibited a marked reduction (P < 0.5) in the number of wet dog shakes when compared to saline-pretreated rats. Similarly, little visible brain damage was found in the (-)-nicotine-pretreated rats, but a widespread reduction in acetylcholinesterase-positive neurons was noted in the hippocampal areas of the saline-pretreated animals. While the mechanism of neuroprotection of (-)-nicotine is still not known, these findings suggest that (-)-nicotine may act as a therapeutic agent for putative excitotoxin-mediated disorders.

Animals↗
PubMed1995

Adoptive transfer of ex vivo activated memory T-cells with or without cyclophosphamide for advanced metastatic melanoma: results in 36 patients.

Autolymphocyte therapy (ALT) is the infusion of autologous peripheral blood mononuclear cells (PBMC) activated ex vivo by a cytokine-rich supernatant (T3CS) generated from a previous autologous lymphocyte culture using low doses of the anti-CD3 mitogenic monoclonal antibody. The mechanism of action is enhancement of a recall response by CD45RO+ (memory) T-cells (ALT cells) to host tumour without dependence on exogenous interleukin (IL)-2. The existence of anti-tumour-specific T-cells in melanoma patients has been well described, and efforts to utilise them therapeutically have achieved modest tumour response rates. However, few long-term survival data have been reported. From 1986 to 1992, we treated 36 patients with disseminated melanoma using ALT alone (26 patients) or adoptive chemoimmunotherapy using ALT and cyclophosphamide (CY) (10 patients). Over this time period, the cell activation method evolved from using cytokine supernatants derived from a one-way allogeneic mixed lymphocyte culture (MLCS), to the current practice of utilising anti-CD3 and autologous cytokines (T3CS). There were 21 men and 15 women, average age 57 years, range 30-82. 27 had failed prior therapies and 9 had no prior therapy. A total of 161 infusion of ALT cells were given: 65 with cells activated in MLCS and 96 with T3CS. There were no grade 3 adverse events, and an approximate 20% incidence of grades 1 and 2 reactions to ALT-cell infusions. Transient cytopenias were seen in patients receiving CY. Sixty-one per cent (22/36) of patients received the planned six ALT-cell infusions, while 39% did not due to progressive disease. In 33 evaluable patients, there were four complete responses, four partial responses and 6 patients with stable disease (SD). Responding patients and those with SD had prolonged survival compared to historical controls when matched for number of organ systems involved. Ex vivo depletion of CD45RO+ T-cells revealed preferential lysis of autologous and HLA-A-matched melanoma targets that was dependent on these memory T-cells. These data suggest that adoptive cellular therapy using ex vivo activated memory T-cells with and without CY is active, has low toxicity, is tumour-specific and can result in clinical benefit in patients with disseminated melanoma.

Adult↗