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Biomedical subjects

J M McKinney

Publications and source records attributed to J M McKinney.

10 recordsLinked to original sources
PubMed2004

Midterm outcome of endovascular abdominal aortic aneurysm repair in octogenarians: a single institution's experience.

OBJECTIVES: We analyzed midterm durability of endovascular abdominal aortic aneurysm repair (EVAR) in octogenarians compared with younger patients. METHODS: Data for 182 consecutive patients who underwent elective EVAR between 1999 and 2003 were retrospectively reviewed. Forty-nine patients (27%) were 80 years or older (study group [SG]; mean age, 84 years; range, 80-89 years), and 133 patients (73%) were younger (control group [CG]; mean age, 72 years; range, 53-79 years). Chi2 analysis, Fisher exact test, Student t test, and Mann-Whitney U test were used as appropriate to test for intergroup differences. Kaplan-Meier curves, log-rank tests, and multivariate Cox models were used for time-to-event analysis, with P < or =.05 considered significant. RESULTS: Mean follow-up was 16 months (range, 1-43 months). Body weight was higher (P <.001), and elevated plasma lipid levels (59% vs 43%; P =.042) and use of nicotine (47% vs 29%; P =.015) more frequent in the octogenarians. Baseline aneurysm size, procedure-related data, and hospital stay were comparable between groups. Aneurysm-related mortality was 0% in the study group and 0.7% in the control group (P =.740). Systemic complications occurred in 22% (SG) versus 11% (CG) (P =.035), owing to a rise in serum creatinine concentration greater than 30% of baseline in 14% in the octogenarian group (vs 5% in the CG; P =.048). Groin lymphoceles developed in 12% (SG) versus 2% (CG; P =.013). Technical success was 96% (SG) versus 98% (CG; P =.408), and clinical success was 86% versus 90% (P =.269). No aneurysm rupture occurred during follow-up, and aneurysm-related adverse events were comparable between groups. The estimated risk for any type of endoleak (2.2; 95% confidence interval [CI], 1.1-4.2; P =.023) or type II endoleak (2.1; 95% CI, 1.0-4.3; P = 0.51) was higher in the study group versus the control group; however, this did not affect secondary procedure rates (SG 16% vs CG 12%; estimated risk, SG vs CG,: 1.5; 95% CI, 0.6-3.6; P = 0.420) or aneurysm remodeling (97.2% combined aneurysm sac stabilization or decrease in both groups; P =.592). Aneurysm enlargement occurred in 2.8% (SG 1 vs CG 4; P =.592). CONCLUSION: Elective EVAR in octogenarians appears safe and effective over midterm follow-up, with a temporary decrease in renal function (14%) and postoperative lymphoceles (12%) being the most common postoperative adverse events. Advanced chronologic age is not associated with diminished procedural outcome, clinical success, or postoperative survival, compared with younger age. Because of low perioperative mortality and high procedural success, EVAR may be the preferred approach to abdominal aortic aneurysm treatment in selected elderly patients.

Age Factors↗
PubMed2004

The effect of steam flaked or dry ground corn and supplemental phytic acid on nitrogen partitioning in lactating cows and ammonia emission from manure.

The effect of starch source and supplemental phytic acid (PA) on N partitioning and excretion and ammonia volatilization from dairy manure was evaluated with 8 midlactation cows. Cows were randomly assigned to treatments in replicated 4 x 4 Latin squares with four 18-d periods. Diets were 61% forage, 25% starch, 17.2% crude protein, and 31% neutral detergent fiber and included dry ground corn (DG) or steam flaked corn (SF) with no supplemental P (L; 0.34% P) or supplemental purified PA (0.45% P) to provide additional P from a non-mineral source. Total collection of milk, urine, and feces was conducted on d 16 to 18 of each period. Cows fed SF had lower dry matter (DM) intakes than those fed DG, which, in addition to increased starch digestibility and ruminal fermentation, contributed to higher DM digestibility. Cows fed SF had reduced feces and urine excretion compared with cows fed DG. Also, N intake for cows fed SF was lower, and N digestibility was higher, compared with cows fed DG; therefore, N excretion in both feces and urine was reduced in these cows. Despite the differences in DM intake, lactation performance was not affected by starch sources. Therefore, the efficiency of N utilization increased with SF. Addition of PA did not affect N intake or utilization. Feces and urine were subsampled from each cow, and wet feces and urine were mixed in sealed chambers in the proportions excreted. Ammonia volatilization was measured for 36 h using acid traps sampled on a planned time course. Nitrogen at time zero (A0), rate of ammonia emission (k), and residual N (R) were calculated using the exponential decay model At = A0 e(-kt) + R. Rate of ammonia loss from mixed feces and urine was lower from cows fed SF than from those fed DG. Altering dietary starch source to improve nutrient digestibility and to reduce N excretion by lactating cows may provide opportunity to reduce ammonia losses from manure.

Ammonia↗
PubMed2003

The effect of steam-flaked or dry ground corn and supplemental phytic acid on phosphorus partitioning and ruminal phytase activity in lactating cows.

The effect of starch source and phytic acid (PA) supplementation on phosphorus (P) partitioning and ruminal phytase activity was evaluated in eight midlactation cows (four ruminally cannulated). Cows were randomly assigned to treatments in replicated 4 x 4 Latin squares with four 18-d periods. Diets included dry ground corn (DG) or steam-flaked corn (SF), with no supplemental P (L; 0.33% P) or supplemental purified PA (0.44% P) to provide additional P from a nonmineral source. Total collection of milk, urine, and feces was conducted on d 16 to 18 of each period. Ruminal fluid was sampled and ruminal pH measured every 8 h on d 17 and 18. Milk yield was unaffected by starch source, despite lower DMI by cows fed SF. Cows fed SF had increased DM digestibility compared with those fed DG, and tended to have higher efficiency of milk yield (1.40 vs. 1.35 kg of milk/kg of DMI). Intake and fecal excretion of P was lower in cows fed SF than in cows fed DG. In cows fed SF, milk P as a percentage of P intake increased compared with cows fed DG. Ruminal pH was unaffected by diet, but milk fat content was lower for cows fed SF. Milk yield, DMI, and feed to milk ratio were not affected by supplementation with PA. Although cows fed PA had increased P intake compared with cows fed low P diet, increased P excretion resulted in no differences in apparent P digestibility. Phosphorus balance tended to be higher in cows fed PA, but milk P as a percentage of intake was reduced. The interaction of starch source and PA affected ruminal phytase activity. Altering starch source to improve efficiency of milk yield in lactating dairy cows may help reduce P losses from dairy farms.

6-Phytase↗
PubMed2002

Effect of a direct-fed fibrolytic enzyme formulation on nutrient intake, partitioning, and excretion in early and late lactation Holstein cows.

The effect of a fibrolytic enzyme formulation on N and P intake, partitioning, and excretion was evaluated in dairy cows in early and late lactation. Twelve lactating Holstein cows (6 early lactation, 6 late lactation) were fed diets with or without the enzyme formulation in a switchback design with three, 4-wk periods. Diets for the early lactation group contained 45% forage, and late lactation diets contained 61% forage. Cows fed diets containing the enzyme formulation gained more weight than those on the control diet; this weight gain with enzyme addition was greater in early lactation cows than in late lactation cows. The main effect of enzyme treatment did not significantly affect apparent digestibility or excretion of N and P, or retention of these nutrients in body tissue. Interactions observed between the effects of group (stage of lactation) and treatment indicated differences in the nature of the milk yield and manure excretion responses to enzyme treatment between early and late lactation cows. These interactions were due to numerical increases in milk yield, feces excretion, and N excretion in early lactation cows fed diets containing the enzyme formulation compared to control, and slight decreases in these measures in late lactation cows with enzyme addition. Cows fed diets containing a direct-fed fibrolytic enzyme formulation had increased body weight gain, but the effect of addition of the enzyme formulation on milk yield and manure nutrient excretion differed for early and late lactation cows.

Animal Nutritional Physiological Phenomena↗
PubMed1997

Renal angiomyolipomas: long-term follow-up of embolization for acute hemorrhage.

OBJECTIVE: To determine if elective, angiographically directed embolization of enlarged renal angiomyolipomas can be used to prevent future hemorrhagic episodes in patients with tuberous sclerosis and thus avoid nephrectomy. PATIENTS AND METHODS: Records were reviewed for all 5 patients who underwent elective, subtotal embolization of large, symptomatic angiomyolipomas at the authors' institution between 1975 and 1996. RESULTS: All 5 patients had tuberous sclerosis and bilateral renal angiomyolipomas. Initial embolization in these patients was performed in 1975, 1981, 1993 (2 patients) and 1994. In 1 patient only a single embolization session was required. In another, initial embolization on the left side was followed by embolization on the right 13 months later. Two patients underwent 2 sessions, and 1 patient had 4 sessions over a 13-year period. Subtotal embolization with particulate material led to a decrease in size of the most severely affected portion of the kidney. One large angiomyolipoma underwent sterile liquefaction after embolization; percutaneous catheter drainage was required. The embolization allowed subsequent partial nephrectomy in this patient. CONCLUSION: Embolization is effective for the long-term management of renal angiomyolipomas in patients with tuberous sclerosis; in this way nephrectomy and loss of renal function can usually be avoided.

Acute Disease↗
PubMed1995

Dimenhydrinate pretreatment in patients receiving intra-arterial ioxaglate: effect on nausea and vomiting.

OBJECTIVE: To determine the effectiveness of the antihistamine dimenhydrinate (Dramamine) as a prophylactic agent against the nausea and vomiting that occasionally accompany the use of ioxaglate. PATIENTS AND METHODS: Three hundred patients (165 men and 135 women, ranging in age from 18 to 89 [mean 62] years) undergoing noncoronary arteriography received dimenhydrinate or placebo before the injection of the low-osmolality contrast material ioxaglate (Hexabrix). The patients were observed and questioned about nausea and vomiting, as well as many other possible reactions to the contrast material. RESULTS: There were no statistical differences in the occurrence of adverse reactions between the groups receiving dimenhydrinate and placebo (chi 2 or Fisher's exact test, p > 0.05). CONCLUSION: Dimenhydrinate, as administered in this study, was ineffective as a prophylactic agent against adverse reactions accompanying administration of ioxaglate.

Adolescent↗
PubMedDate not supplied

Computed tomography of children and adolescents with suspected spinal stenosis.

Spinal stenosis in children and adolescents is a rare condition that should be considered in patients with appropriate clinical signs and symptoms. We describe and discuss four cases of spinal stenosis in children and adolescents diagnosed by CT. In all these cases, CT was beneficial at demonstrating and defining the nature and location of suspected spinal stenosis.

Adolescent↗
PubMedDate not supplied

Assessing the adequacy of peripherally inserted central catheters for power injection of intravenous contrast agents for CT.

PURPOSE: The purpose of this work was to determine the tolerance of silicone peripherally inserted central catheters (PICCs) of different sizes and lengths to power injection of contrast materials at flow rates suitable for CT studies. METHOD: Fifty silicone PICCs in three single-lumen sizes (3 to 5F) and two double-lumen sizes (6 and 7F) were cut to two lengths (35 and 45 cm), and a uniform volume of 74% ioversol was injected into each at increasing rates of flow by a power injector. The flow rate, volume, and peak pressure were recorded for each injection. RESULTS: The respective tolerated flows for the 35 and 45 cm PICCs were 0.65 ml/s at 125 psi and 0.56 ml/s at 125 psi for the 3F catheters, 1.58 ml/s at 150 psi and 1.04 ml/s at 150 psi for the 4F catheters, 4.20 ml/s at 200 psi and 3.02 ml/s at 170 psi for the 5F catheters, 1.50 ml/s at 145 psi and 0.88 ml/s at 150 psi for the 6F catheters, and 9.52 ml/s at 350 psi and 8.78 ml/s at 330 psi for the 7F catheters. CONCLUSION: The 3F catheters were unsuitable for power injection for CT studies because they could not accommodate adequate flow rates. The 4F single-lumen and 6F double-lumen catheters withstood flow rates that were marginally adequate for CT studies. The 5F single-lumen and 7F double-lumen PICCs tolerated peak flows and pressures well within the range necessary to allow power injection of contrast materials for CT studies. For each size of PICC, the 35 cm length withstood higher flow rates than the 45 cm length before failure.

Analysis of Variance↗
PubMedDate not supplied

The AAPM/RSNA physics tutorial for residents: digital fluoroscopy.

A digital fluoroscopy system is most commonly configured as a conventional fluoroscopy system (tube, table, image intensifier, video system) in which the analog video signal is converted to and stored as digital data. Other methods of acquiring the digital data (eg, digital or charge-coupled device video and flat-panel detectors) will become more prevalent in the future. Fundamental concepts related to digital imaging in general include binary numbers, pixels, and gray levels. Digital image data allow the convenient use of several image processing techniques including last image hold, gray-scale processing, temporal frame averaging, and edge enhancement. Real-time subtraction of digital fluoroscopic images after injection of contrast material has led to widespread use of digital subtraction angiography (DSA). Additional image processing techniques used with DSA include road mapping, image fade, mask pixel shift, frame summation, and vessel size measurement. Peripheral angiography performed with an automatic moving table allows imaging of the peripheral vasculature with a single contrast material injection.

Angiography, Digital Subtraction↗