Biomedical subjects

C Ayers

Publications and source records attributed to C Ayers.

At least 19 recordsLinked to original sources

PubMed2006

A method for quantifying birthweight discordance in quadruplets and potential use in predicting early mortality.

We describe an approach to quantify birthweight discordance in quadruplets and assessed its potential use in predicting infant mortality. Retrospective cohort study on quadruplets delivered in the United States from 1995 through 2000 inclusive. The main outcome measures were infant, neonatal, and postneonatal mortality. A total of 2692 quadruplet live births (673 complete clusters) with complete information on gestational age, birthweight, and survival within the first year. Of the total 673 quadruplet clusters, discordance occurred in 180 sets (26.7%). The predominant discordant type was a single discordant individual within a cluster (177 sets or 99.8%), whereas only three sets (0.2%) recorded up to two discordant quadruplets within a cluster. The period of pronounced risk for the occurrence of birthweight discordance was between 28 and 35 gestational weeks. Discordant individuals exhibited elevated risk for infant (adjusted odds ratio [aOR] = 2.1; 95% confidence interval [CI], 1.4 to 3.0), neonatal (aOR = 1.8; 95% CI, 1.2 to 2.6), and postneonatal (aOR = 2.9; 95% CI, 1.1 to 8.4) mortality. After adjusting for small for gestational age, the risk for postneonatal mortality among discordant infants quadrupled (aOR = 4.1; 95% CI, 1.5 to 10.8). The population-attributable risks were 18, 20, and 46% for neonatal, infant, and postneonatal mortality, respectively. The new method is predictive of mortality at all stages of infancy. Discordance accounts for 18 to 46% of all quadruplet deaths during infancy in the United States.

Adult↗

PubMed2005

Screening women with menorrhagia for underlying bleeding disorders: the utility of the platelet function analyser and bleeding time.

Menorrhagia is a very common clinical problem among women of reproductive age and recent studies have suggested that underlying bleeding disorders, particularly von Willebrand's deficiency and platelet function defects, are prevalent in women presenting with menorrhagia. The objective of this study was to determine the utility of the platelet function analyser (PFA-100) and bleeding time (BT) as initial screening tests for underlying bleeding disorders in women with menorrhagia. In this study, 81 women with a physician diagnosis of menorrhagia underwent PFA-100 testing, BT and comprehensive haemostatic testing. The effectiveness of the PFA-100 and BT as screening tools in women with menorrhagia was assessed using results of haemostatic testing for von Willebrand's disease (VWD) and platelet dysfunction. In women presenting with menorrhagia, the PFA-100 had a sensitivity 80%, specificity 89%, positive predictive value (PPV) 33%, negative predictive value (NPV) 98% and efficiency 88% for VWD. For platelet aggregation defects, the PFA-100 closure time had a sensitivity 23%, specificity 92%, PPV of 75%, NPV of 52% and efficiency 55%. The data suggest that the PFA-100 may be useful in stratifying women with menorrhagia for further von Willebrand testing; however, neither the PFA-100 nor the BT tests are effective for purposes of classifying women for standard platelet aggregometry testing in women presenting with menorrhagia.

Adolescent↗

PubMed1999

Activation of human monocytic cells by Borrelia burgdorferi and Treponema pallidum is facilitated by CD14 and correlates with surface exposure of spirochetal lipoproteins.

Here we examined the involvement of CD14 in monocyte activation by motile Borrelia burgdorferi and Treponema pallidum. B. burgdorferi induced secretion of IL-8 by vitamin D3-matured THP-1 cells, which was inhibited by a CD14-specific mAb known to block cellular activation by LPS and the prototypic spirochetal lipoprotein, outer surface protein A. Enhanced responsiveness to B. burgdorferi also was observed when THP-1 cells were transfected with CD14. Because borreliae within the mammalian host and in vitro-cultivated organisms express different lipoproteins, experiments also were performed with "host-adapted" spirochetes grown within dialysis membrane chambers implanted into the peritoneal cavities of rabbits. Stimulation of THP-1 cells by host-adapted organisms was CD14 dependent and, interestingly, was actually greater than that observed with in vitro-cultivated organisms grown at either 34 degrees C or following temperature shift from 23 degrees C to 37 degrees C. Consistent with previous findings that transfection of Chinese hamster ovary cells with CD14 confers responsiveness to LPS but not to outer surface protein A, B. burgdorferi failed to stimulate CD14-transfected Chinese hamster ovary cells. T. pallidum also activated THP-1 cells in a CD14-dependent manner, although its stimulatory capacity was markedly less than that of B. burgdorferi. Moreover, cell activation by motile T. pallidum was considerably less than that induced by treponemal sonicates. Taken together, these findings support the notion that lipoproteins are the principle component of intact spirochetes responsible for monocyte activation, and they indicate that surface exposure of lipoproteins is an important determinant of a spirochetal pathogen's proinflammatory capacity.

Animals↗

PubMed1999

Renal insufficiency: usefulness of gadodiamide-enhanced renal angiography to supplement CO2-enhanced renal angiography for diagnosis and percutaneous treatment.

PURPOSE: To determine whether gadodiamide is a safe and useful angiographic contrast agent for help in diagnosis and percutaneous treatment of renal artery stenosis in patients with renal insufficiency. MATERIALS AND METHODS: Diagnostic renal angiography and percutaneous renal interventions were performed by using gadodiamide (total dose, 0.3 mmol/kg) and CO2 as intraarterial contrast agents in 25 procedures in 24 patients with renal insufficiency. Serum creatinine levels were obtained within 24 hours before and at 24 and 48 hours after the procedure. Increases in serum creatinine of more than 44 mumol/L were considered clinically important. Gadodiamide-enhanced angiograms were compared with CO2-enhanced angiograms. RESULTS: In 23 (92%) of 25 procedures, there was no increase in serum creatinine level at 48 hours. One patient with acute and chronic rejection of a renal transplant and one with evidence of cholesterol embolization had a clinically important increase in serum creatinine level at 48 hours. No marked increase in creatinine level was observed in patients with relatively low baseline levels (n = 19). Gadodiamide-enhanced angiograms appeared to be better than CO2-enhanced angiograms for help in identifying renal artery occlusions, visualizing renal vessels incompletely filled with CO2, and determining the progress of intervention. CONCLUSION: Gadodiamide appears to be a safe and useful intraarterial contrast agent in patients with renal insufficiency and can be used to supplement or confirm CO2-enhanced angiographic findings.

Acute Disease↗

PubMed1999

Surgical closing in total knee arthroplasty. A series followup.

The benefits of closing the surgical wound of a primary and revision total knee prosthesis with the knee in full flexion are examined. A previous study showed that surgically closing the primary knee arthroplasty with the knee in full flexion produced significantly more postoperative flexion at 6 months: 114.7 degrees compared with 108.1 degrees. Of 108 selected sequential primary knee arthroplasties, the first 52 knees were closed surgically with the leg in full knee extension, and the second 56 knees were closed in 90 degrees to 110 degrees flexion, depending on the available motion of the joint. The patients in each group were matched closely in age, weight, height, gender, and surgical technique. At all followup intervals, the flexion measurements were significantly better in the flexion closure group. At 1 year, the flexion group had 117.9 degrees and the extension group had 112.9 degrees flexion. The revision series also was a selected sequential series with 13 knees in each closure group. In the revision case, the 1-year findings were similar, with significantly more knee flexion in the flexion closure group (118.7 degrees compared with 112.7 degrees). In matched groups, flexion closure in primary and revision knee replacements significantly increased total range of motion, as seen at the 1-year followup.

Aged↗

PubMed1996

Surgical closing in primary total knee arthroplasties: flexion versus extension.

One hundred eight consecutive patients with primary osteoarthritis of the knee undergoing primary arthroplasty were compared retrospectively to determine whether surgical closure of the entire wound in flexion has any effect on range of motion postoperatively over a period of up to 6 months. The knees of the first 52 patients were surgically closed in extension. In the second group of 56 patients, the knees were closed in 90 degrees to 110 degrees flexion depending on the available motion of the joint. Although the patients were not randomized, the groups were closely matched in age, weight, height, and gender. Preoperative and postoperative patellar heights were similar in both groups. The patients were started on a continuous passive motion device in the recovery room. At all intervals the flexion measurements were significantly better in the flexion closure group. By 6 months the flexion closure group had surpassed their preoperative measurements, whereas the extension closure group had not yet achieved this goal. The flexion group required less home physical therapy than the extension group. Closing the knee in flexion permits the patients to regain knee motion faster with less effort, thereby saving money and enhancing patient satisfaction.

Aged↗

PubMed1994

Whole blood and plasma concentrations of 4-hydroxy-2-nonenal in Watanabe heritable hyperlipidemic versus New Zealand White rabbits.

Both plasma and whole blood concentrations of 4-hydroxy-2-nonenal (4HNE) were significantly elevated in a population (n = 6) of 2 year old Watanabe heritable hyperlipidemic rabbits relative to a population (n = 6) of New Zealand White rabbits. The plasma concentrations were 74 +/- 10 nmol/L for the Watanabe group and 47 +/- 6 nmol/L for the New Zealand White group. The whole blood concentrations were 364 +/- 55 nmol/L for the Watanabe group and 188 +/- 64 nmol/L for the New Zealand White group. These results indicate that 4HNE concentrations in blood can be elevated in individuals with atherosclerosis and demonstrate the potential link between the formation of 4HNE and the progression of atherosclerosis.

Aldehydes↗

PubMed1991

Results and complications of angioplasty in fibromuscular disease.

Percutaneous transluminal angioplasty (PTA) was used to treat 66 patients with 85 renal artery stenoses due to fibromuscular dysplasia. The hypertension was refractory to medical management in 46 patients, and the initial success rate was 100%. Clinical follow-up has been obtained in all patients, who were followed for as long as 121 months. The recurrence rates were 8% of lesions and 10% of patients. Cumulative patency rate predicted for 10 years was 87.07%. The mean systolic pressure decreased by 52 mm Hg and the mean diastolic pressure decreased by 35 mm Hg in response to treatment. Twenty-six patients (39%) were cured, 39 (59%) were classified as improved, and one (2%) did not respond to PTA. Fourteen of the patients also had elevated blood urea nitrogen and creatinine levels. Renal function was improved in 86% of the patients and stabilized in 14% of the patients. Analysis of the long-term results suggests that PTA should be the initial treatment for choice of patients with fibromuscular dysplasia in the renal arteries.

Angioplasty, Balloon↗

PubMed1988

Effect of intravenous enalaprilat in moderate and severe systemic hypertension.

The antihypertensive effect and tolerability of enalaprilat, an intravenously administered angiotensin converting enzyme inhibitor, was studied in 65 patients with moderate or severe hypertension. In this randomized, double-blind study, enalaprilat was compared with placebo in 42 (22 enalaprilat, 20 placebo) moderate hypertensive (diastolic blood pressure [BP] 100 to 114 mm Hg) patients. It was compared with furosemide in 23 (12 enalaprilat, 11 furosemide) severe hypertensive (diastolic BP 115 to 130 mm Hg) patients. Enalaprilat (1.25 or 5.0 mg), placebo (5% dextrose) or furosemide (40 or 80 mg) was given every 6 hours intravenously up to 48 hours. In the moderate hypertension stratum, the mean supine diastolic BP was significantly (p less than or equal to 0.01) reduced from baseline at all timepoints in the enalaprilat group. These diastolic BP reductions were significantly (p less than or equal to 0.01) greater in the enalaprilat group than the placebo at 1 to 24 hours (-12 vs -4 mm Hg), with 59% of the patients responding to enalaprilat compared with 30% of the patients responding to placebo. An even greater reduction (p less than or equal to 0.01) was seen at 25 to 48 hours (-14 vs -7 mm Hg, with 73% enalaprilat vs 58% placebo responders). Significant (p less than or equal to 0.01) reductions in mean, supine systolic BP were also seen at 1 to 24 hours (-22 vs -2 mm Hg) and 25 to 48 hours (-24 vs -8 mm Hg) during the 48 hours of the double-blind treatment phase in the enalaprilat group compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗

PubMed1986

Increased uptake and accumulation of catecholamines by red blood cells in phaeochromocytoma.

Red blood cell (RBC) and plasma catecholamine content were determined by high performance liquid chromatography in 18 patients suspected of having phaeochromocytoma on the basis of clinical manifestations, especially hypertension and laboratory findings. Eight normotensive health individuals served as controls. The fivne patients with tumours had strikingly greater RBC catecholamine concentrations (C) than in plasma and reached CRBS/Cplasma ratios approximating 5, significantly different from the ratios in controls and in hypertensive patients without tumours. One tumour patient had a normal RBC catecholamine content as well as repeatedly normal plasma and urinary catecholamine levels. The other 12 patients, who had no ++tumours, had only slight elevations in plasma and RBC catecholamine levels. There is an accelerated uptake of catecholamines against a concentration gradient by the RBC in phaeochromocytoma, which indicates that RBC play a major role in the clearance of catecholamines after they are secreted into circulation.

Adrenal Gland Neoplasms↗

PubMed1984

Percutaneous transluminal angioplasty of the renal artery. Results and long-term follow-up.

Percutaneous transluminal angioplasty (PTA) was used to treat 109 patients with 141 renal artery stenoses, including 58 patients in whom medical management was unsuccessful. The initial success rate was 94%. Fifty-five patients had severe diffuse atherosclerosis and 40 had renal insufficiency. Thus far, 36 patients (50 stenoses) have undergone a total of 52 follow-up angiographic studies. Clinical data, including blood pressure response, were obtained in all cases. Only 7 of the 98 hypertensive patients failed to respond to PTA. Of the 11 patients treated primarily for renal insufficiency, 5 improved. Of the 29 hypertensive patients who also had elevated BUN and creatinine, renal function improved in 13. Altogether, 96 patients (88%) benefited from the procedure. Analysis of long-term results suggests that PTA should be the treatment of choice for fibromuscular dysplasia and short, segmental atherosclerotic lesions and could also prove helpful in improving renal insufficiency.

Adolescent↗

PubMed1981