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W S Moore

Publications and source records attributed to W S Moore.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effects of thrombus, thrombectomy and thrombolysis on endothelial function.

OBJECTIVE: this study was undertaken to examine and compare the effects of thrombus, thrombectomy, and thrombolysis on endothelial function as measured by endothelium-dependent vasorelaxation (EDR). METHODS: adult, male New Zealand white rabbits underwent ligation of the left common iliac to femoral artery to induce thrombosis and were then randomly assigned to one of five groups, n=6 in each. Group A consisted of ligation and thrombosis for 4 h. Group B underwent similar ligation for 4 h, but without intraluminal thrombus present. Following 4 h of ligation and thrombosis, Group C underwent thrombectomy while group D was treated with urokinase (UK), 4000 U/min for 30 min. Group E underwent UK infusion alone. The right external iliac artery served as control vessel in each group. All arteries were removed and endothelial function was determined by measuring EDR. RESULTS: the presence of thrombus reduced EDR by 50% (group A) compared to control. Vessels with interrupted flow, but not exposed to thrombus, retained normal EDR (group B). Thrombectomy decreased EDR significantly (group C) compared to thrombolysis (group D) and control. UK did not significantly alter EDR (groups D, E). CONCLUSIONS: exposure of endothelium to thrombus significantly decreases EDR. EDR was not affected by interruption of blood flow in the absence of thrombus. Thrombectomy appeared to cause a further additive insult to the endothelium. In contrast, thrombolysis with UK preserved residual endothelial function. These data suggest that it is important to differentiate the effects of thrombus on endothelium from effects due to thrombectomy or thrombolysis when evaluating treatment modalities for arterial thrombosis.

Analysis of Variance↗
PubMed2000

Comparative evolution of the mitochondrial cytochrome b gene and nuclear beta-fibrinogen intron 7 in woodpeckers.

Most molecular phylogenetic studies of vertebrates have been based on DNA sequences of mitochondrial-encoded genes. MtDNA evolves rapidly and is thus particularly useful for resolving relationships among recently evolved groups. However, it has the disadvantage that all of the mitochondrial genes are inherited as a single linkage group so that only one independent gene tree can be inferred regardless of the number of genes sequenced. Introns of nuclear genes are attractive candidates for independent sources of rapidly evolving DNA: they are pervasive, most of their nucleotides appear to be unconstrained by selection, and PCR primers can be designed for sequences in adjacent exons where nucleotide sequences are conserved. We sequenced intron 7 of the beta-fibrinogen gene (beta-fibint7) for a diversity of woodpeckers and compared the phylogenetic signal and nucleotide substitution properties of this DNA sequence with that of mitochondrial-encoded cytochrome b (cyt b) from a previous study. A few indels (insertions and deletions) were found in the beta-fibint7 sequences, but alignment was not difficult, and the indels were phylogentically informative. The beta-fibint7 and cyt b gene trees were nearly identical to each other but differed in significant ways from the traditional woodpecker classification. Cyt b evolves 2.8 times as fast as beta-fibint7 (14. 0 times as fast at third codon positions). Despite its relatively slow substitution rate, the phylogenetic signal in beta-fibint7 is comparable to that in cyt b for woodpeckers, because beta-fibint7 has less base composition bias and more uniform nucleotide substitution probabilities. As a consequence, compared with cyt b, beta-fibint7 nucleotide sites are expected to enter more distinct character states over the course of evolution and have fewer multiple substitutions and lower levels of homoplasy. Moreover, in contrast to cyt b, in which nearly two thirds of nucleotide sites rarely vary among closely related taxa, virtually all beta-fibint7 nucleotide sites appear free of selective constraints, which increases informative sites per unit sequenced. However, the estimated gamma distribution used to model rate variation among sites suggests constraints on some beta-fibint7 sites. This study suggests that introns will be useful for phylogenetic studies of recently evolved groups.

Animals↗
PubMed2000

Magnetic resonance imaging in dentistry.

MR imaging has found a place in the imaging sciences. These images are unique in that no ionizing radiation is used, the same tissues may or may not have different appearances with different machine settings, a unique set of terms is used to describe the findings in the images, and these findings can be analyzed with the view of obtaining more diagnostic information not readily available with any other imaging modality. Cases have been presented to help demonstrate differences in T1-weighted and T2-weighted sequences as well as the value of contrast material. Additionally, plain film and CT views were included so that they may be contrasted with the MR images. The role and application of CT versus MR imaging has been further discussed and illustrated by Nortjé and van Rensburg. A typical temporomandibular joint case has also been presented. In the future, it is hoped that clinicians will refer more patients for MR imaging so that diagnoses can be made more accurately with analytic software.

Adult↗
PubMed2000

Osteosarcoma.

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Adult↗
PubMed2000

Rosacea.

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Adult↗
PubMed1999

Exposure to thrombus diminishes endothelial derived relaxation in the rabbit carotid artery.

PURPOSE: Thrombus is believed to be deleterious to intimal function. However, few studies have directly examined this effect. This study examines the effect of thrombus on endothelial-dependent and -independent vasorelaxation in the rabbit carotid artery. METHODS: Twelve male New Zealand white rabbits (3.5-4.5 kg) were divided into two groups of six. Thrombosis was induced in group I by segmental right carotid artery ligation. Group II underwent segmental right carotid ligation immediately followed by removal of thrombus with normal saline flush through an arteriotomy. The left carotid arteries were exposed in both groups and served as internal controls. After 4 h, left and right carotid arteries were harvested, sectioned into 6-mm rings, and mounted on isometric force transducers in a physiologic bath. Thrombus was removed from the arteries in group I during the ring preparation process. Neither group I nor group II had thrombus in contact with endothelium during ex vivo testing. The arterial rings were constricted with norepinephrine (1 x 10(-4) M). Endothelium-dependent and -independent vasorelaxation to acetylcholine (Ach) and s-nitrosoacetylpenicillamine, respectively, were measured in a dose-response manner. Results were expressed as a percentage of vasorelaxation. Statistical analysis was performed using an analysis of variance. RESULTS: Endothelial-dependent vasorelaxation, which tests for endothelial cell function, was decreased in the thrombus and endothelial ischemia group (I) compared to control as noted by vasorelaxations of 22% vs 34% at 1 x 10(-4) molar concentration Ach, and 33% vs 48% at 1 x 10(-3) molar concentration Ach, respectively (P = 0.05). By comparison, there was no difference in the endothelial-dependent vasorelaxation of the endothelial ischemia group (II) versus control. Endothelial-independent vasorelaxation, which tests for smooth muscle function, was not affected by either the thrombus and endothelial ischemia group (I) or the endothelial ischemia group (II) compared to the control group. The controls in group I and group II were slightly different. When this difference was removed, the resulting comparison of treatments in group I and group II approached significance at molar concentrations of 1 x 10(-4), 1 x 10(-5), and 1 x 10(-6) (P = 0.07, 0.06, 0.06). CONCLUSIONS: The presence of thrombus within the rabbit carotid artery for a period of 4 h decreases endothelial-dependent relaxation. Four hours of endothelial ischemia without thrombus did not change endothelial-dependent vasorelaxation. Neither thrombus nor ischemia alone had any effect on the endothelium-independent vasorelaxation. We conclude that thrombus is deleterious to endothelial function independent of smooth muscle function in the acute setting as measured by endothelial-dependent vasorelaxation.

Acetylcholine↗
PubMed1999

Endovascular, transperitoneal, and retroperitoneal abdominal aortic aneurysm repair: results and costs.

PURPOSE: Contemporary treatment of abdominal aortic aneurysms (AAA) includes transabdominal (TA), retroperitoneal (RP), and endovascular (EV) repair. This study compares the cost and early (30-day) results of a consecutive series of AAA repair by means of these three methods in a single institution. METHODS: A total of 125 consecutive AAA repairs between February 1993 and August 1997 were reviewed. Risk factors, 30-day morbidity and mortality rates, and hospital stay and cost were analyzed according to method of repair (TA, RP, EV). Cost was normalized by means of a conversion factor to maintain confidentiality. Cost analysis includes conversion to TA repair (intent to treat) in the EV group. RESULTS: One hundred twenty-five AAA repairs were performed with the TA (n = 40), RP (n = 24), or EV (n = 61) approach. Risk factors among the groups (age, coronary artery disease, hypertension, diabetes, chronic obstructive pulmonary disease, and cigarette smoking) were not statistically different, and thus the groups were comparable. The average estimated blood loss was significantly lower for EV (300 mL) than for RP (700 mL) and TA (786 mL; P>.05). Statistically significant higher cost for TA and RP for pharmacy and clinical laboratories (likely related to increased length of stay [LOS]) and significantly higher cost for EV in supplies and radiology (significantly reducing cost savings in LOS) were revealed by means of an itemized cost analysis. Operating room cost was similar for EV, TA, and RP. There were six perigraft leaks (9.6%) and six conversions to TA (9.6%) in the EV group. CONCLUSION: There were no statistically significant differences in mortality rates among TA, RP, and EV. Respiratory failure was significantly more common after TA repair, compared with RP or EV, whereas wound complications were more common after RP. Overall cost was significantly higher for TA repair, with no significant difference in cost between EV and RP. EV repair significantly shortened hospital stay and intensive care unit (ICU) use and had a lower morbidity rate. Cost savings in LOS were significantly reduced in the EV group by the increased cost of supplies and radiology, accounting for a similar cost between EV and RP. Considering the increased resource use preoperatively and during follow-up for EV patients, the difference in cost between TA and EV may be insignificant. EV repair is unlikely to save money for the health care system; its use is likely to be driven by patient and physician preference, in view of a significant decrease in the morbidity rate and length of hospital stay.

Aortic Aneurysm, Abdominal↗
PubMed1999

Carotid artery repair for radiation-associated atherosclerosis is a safe and durable procedure.

OBJECTIVE: The development of carotid atherosclerosis after neck irradiation is well documented. There has been concern about the safety and durability of carotid artery repair through a radiated field. The objective of this report is to describe the immediate and long-term results of a series of cases collected in a 13-year interval. METHODS: From 1984 to 1997, 24 patients underwent 26 carotid artery operations. All the patients had undergone prior radiation therapy at a mean interval of 17 years, with an average radiation dose of 6300 rad. Severe scarring of the skin or radiation fibrosis were present in two thirds of the patients, with 4 patients having permanent tracheostomies. The indications for carotid surgery included cerebral or monocular transient ischemic attack (58%), asymptomatic high-grade stenosis (27%), prior stroke (12%), and tumor invasion of the carotid artery (4%). General anesthesia was used with selective shunting on the basis of carotid artery back pressure or electroencephalography monitoring. Patch angioplasty closure was used in 79% of the patients. The operations included standard carotid endarterectomy (n = 20), external carotid endarterectomy (n = 2), carotid patch angioplasty alone (n = 2), aortocarotid bypass grafting (n = 1), and carotid interposition grafting (n = 1). Four patients required skin grafting or myocutaneous flaps. RESULTS: No deaths or strokes occurred within 30 days of the operations. Six patients had transient cranial nerve palsy, and two had wound infections. The patients were followed from 1 to 156 months, with six patients being followed for longer than 18 months. No strokes were seen at late follow-up examination. Duplex scan examination documented one occlusion, in a patient with primary closure, and two restenoses, one of which necessitated reoperation. The remainder of the grafts were widely patent. CONCLUSIONS: Carotid surgery after neck irradiation is safe and durable. The long-term patency rates and the protection against subsequent neurologic events are similar to the results obtained in the absence of radiation therapy. Problems of wound healing were not found in this series.

Aged↗
PubMed1999

Abdominal aortic aneurysm: a 6-year comparison of endovascular versus transabdominal repair.

OBJECTIVE: To test the hypothesis that endovascular repair of abdominal aortic aneurysm (AAA) will result in a significant reduction in mortality and morbidity rates and cost when compared with open transabdominal repair. SUMMARY BACKGROUND DATA: Since the introduction of endovascular repair of AAA this decade, multiple groups have evaluated different endovascular grafts. Despite the excellent results reported initially, there has been a paucity of well-controlled, comparative studies looking at long-term outcome. METHODS: From 1992 to 1998, the first 100 consecutive patients undergoing endovascular AAA repair (mean age 74.7, AAA size 5.6 cm) were compared to 100 patients undergoing transabdominal repair (mean age 72.9, AAA size 5.9 cm). All patients undergoing endovascular repair received a device manufactured by Endovascular Technologies, Inc. (Menlo Park, CA) and were prospectively followed with periodic examination, contrast-enhanced computed tomography, and duplex scanning. Of the 200 patients, 198 have been available for long-term follow-up. RESULTS: The two groups had similar preoperative risk factors. Surgical time (211 vs. 256 minutes, p < 0.005), blood loss (326 vs. 1010 ml, p < 0.005), and blood replacement (0.4 vs. 1.6 units, p < 0.005) were all decreased in the endovascular group. Median intensive care unit stay (0 vs. 2 days) and hospital stay (2 vs. 7 days) were significantly reduced in the endovascular group. Insignificant trends in lower morbidity rates (myocardial infarction 1 % vs. 5%, respiratory failure 1 % vs. 5%, colon ischemia 0% vs. 2%) were present in patients undergoing endovascular repair. This led to decreased hospital cost and increased hospital profit. The surgical mortality rate (2% vs. 3%) and 5-year survival rate (65% vs. 72%) have been equivalent between the two groups. CONCLUSIONS: The surgical mortality rate is low for both groups and not statistically different. Endovascular repair significantly reduces resource utilization (surgical time, blood replacement, intensive care unit and hospital stay) and cost when compared to transabdominal aneurysm repair. Long-term survival is equivalent in patients undergoing AAA repair regardless of technique. Although endovascular repair appears durable for up to 6 years, longer follow-up studies are warranted.

Aged↗
PubMed1999

Endovascular repair of abdominal aortic aneurysm using the EVT device: limited increased utilization with availability of a bifurcated graft.

PURPOSE: To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs). METHODS: One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed. RESULTS: Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous. CONCLUSIONS: Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

Aged↗
PubMed1999

Comparative radiopacity of flowable resin composites.

OBJECTIVE: This in vitro investigation aimed to determine the radiopacity of eight recently introduced "flowable" restorative resin composites and to compare their radiodensities to those of enamel, dentin, and a widely used composite marketed for universal application in anterior and posterior teeth. METHOD AND MATERIALS: A total of 45 composite specimens were fabricated in cylindrical molds and exposed to a curing light for 120 seconds. Two methods were used to determine radiopacity: a transmission densitometer and a computer-assisted densitometric image analysis station. RESULTS: Of the eight flowable resin composites tested, only three exhibited a radiopacity equal to or greater than that of enamel, a widely followed guideline for clinicians' diagnostic ability. The radiopacity of the remaining five materials was not statistically significantly greater than that of dentin. CONCLUSION: The level of radiopacity of the tested flowable composites was variable; those with low radiodensity should be avoided in Class II restorations, where a clear determination of recurrent caries by the examining clinician could be compromised.

Absorptiometry, Photon↗
PubMed1998

Two-step cycle sequencing reduces premature terminations when using primers with high annealing temperatures.

Direct cycle sequencing of double-stranded polymerase chain reaction (PCR) products using thermostable polymerases produces fragments that are shorter than expected when the enzyme prematurely detaches as it approaches the 5'-end of the DNA template. These premature terminations result in a substantially reduced reading length of the DNA sequence. Since some DNA templates spontaneously fold and form stable secondary structures at temperatures that are typically used for primer annealing, one factor that may cause premature terminations to occur is the formation of secondary structures in the template during the annealing step of the cycle sequencing reaction. We describe a simple and effective method for reducing premature terminations in DNA sequences. We demonstrate that maintaining the annealing temperature of the cycle sequencing reaction above a critical temperature reduces premature terminations in DNA sequences that regularly contain premature terminations when the temperature of the annealing step is 60 degrees C. In the method described, annealing and extension of the primer along the template take place at the same temperature (72 degrees C). This procedure for reducing premature terminations can be applied when sequencing with primers that are relatively long (at least 27 mer) and have high optimal annealing temperatures.

Animals↗