Biomedical subjects

C L Taylor

Publications and source records attributed to C L Taylor.

At least 37 records · Page 2Linked to original sources

PubMed1996

Temporary vessel occlusion during intracranial aneurysm repair.

Any method that decreases the risk of intraoperative rupture should improve outcome if complications associated with its use do not negate positive effect. If application time is limited and a form of cerebral protection and appropriate monitoring of cerebral function are used, temporary clip application may meet these requirements. The efficacy of temporary occlusion as an adjunct to aneurysm clipping may be limited by technical considerations with respect to regional anatomy, aneurysm size, and aneurysm consistency. In areas of limited access, positioning proximal clips may not be feasible. The use of endovascular techniques of balloon occlusion may provide proximal control in these situations (9, 106). The decision to use total circulatory arrest and profound hypothermia, as opposed to temporary clip application, remains largely a matter of the surgeon's judgment. The role of proximal parent vessel ligation must also be considered in the decision-making process regarding the treatment of giant or technically difficult aneurysms (114). Further refinements in cerebral monitoring that can accurately reflect intracellular processes in all territories affected by the application of temporary clips or balloon occlusion and development of more effective forms of cerebral protection may permit safer use of this technique. An adequately controlled clinical trial of temporary occlusion with or without putative "cerebral protection" is needed to confirm the efficacy of this technique.

Animals↗

PubMed1996

Good clinical outcome in a patient with a large CT scan hypodensity treated with intra-arterial urokinase after an embolic stroke.

Hypodense regions demonstrated by CT within 6 hours of the onset of stroke may reflect irreversibly damaged tissue, and some have suggested that patients with such findings should be spared the risks of thrombolytic therapy since they are unable to benefit from it. We report here a patient with a low-density area demonstrated by CT less than 6 hours after onset of symptoms who improved dramatically after successful intra-arterial thrombolysis.

Cerebral Angiography↗

PubMed1995

Idiom understanding in youth: further examination of familiarity and transparency.

School-age children and adolescents (n = 150) enrolled in Grades 5, 8, and 11 were administered a forced choice task of idiom understanding that controlled for idiom familiarity and transparency. Performance on the task steadily improved during the targeted age range and was affected by the factors of interest: Idioms that were higher in familiarity and transparency were easier for students to understand than those that were less familiar and more opaque. The results of this study provide further support for the language experience hypothesis of figurative language development and for the hypothesis that metalinguistic activity, which itself becomes more sophisticated during the school-age and adolescent years, facilitates later language development. The study also suggests certain methodological implications for future research that examines the development of idiom understanding in youth.

Adolescent↗

PubMed1995

Cerebral arterial aneurysm formation and rupture in 20,767 elderly patients: hypertension and other risk factors.

Cerebral arterial aneurysms are common in the general population and their rupture is a catastrophic event. Considerable uncertainty remains concerning the conditions that predispose individuals to aneurysm formation or rupture. The role of systemic hypertension in aneurysm formation and rupture has been especially controversial. Demographic variables have rarely been addressed because of the small sample sizes in previous studies. The authors describe the demographics and prevalence of hypertension in 20,767 Medicare patients with an unruptured aneurysm and compared these to a random sample of the hospitalized Medicare population. The prevalence of hypertension in patients with unruptured aneurysms was 43.2% compared with 34.4% in the random sample. Patients who survived their initial hospitalization were separated into two groups: those with an unruptured cerebral aneurysm as the primary diagnosis and those with an unruptured cerebral aneurysm as a secondary diagnosis. Follow-up data for 18,119 patients were examined to determine the risk of subarachnoid hemorrhage (SAH) associated with age, gender, race, hypertension, insulin-dependent diabetes mellitus, and surgical treatment. For patients with an unruptured cerebral aneurysm as the primary diagnosis, hypertension was found to be a significant risk factor for future SAH (risk ratio: 1.46, 95% confidence interval (CI): 1.01-2.11), whereas surgical treatment (risk ratio: 0.29, 95% CI: 0.09-0.97) had a significant protective effect. Advancing age had a small but significant protective effect in both groups. Elderly patients identified with unruptured aneurysms are more likely to have coexisting hypertension than the general hospitalized population. In elderly patients hospitalized with an unruptured cerebral aneurysm as their primary diagnosis, hypertension is a risk factor for subsequent SAH, whereas surgical treatment is a protective factor against SAH.

Age Factors↗

PubMed1994

Changing incidence and etiology of iatrogenic ureteral injuries.

In the last decade there have been major advances in endoscopic surgery including ureteroscopy and laparoscopy, both of which may cause ureteral injury. We sought to determine if increased use of these procedures affected the frequency and nature of major iatrogenic ureteral injuries managed at our medical center. From 1980 to 1984 we treated 8 patients with such injuries compared to 19 patients treated from 1985 to 1989. The most recent period corresponded to the institution of ureteroscopy and the use of more aggressive laparoscopic procedures. Of the patients 14 sustained injuries at our center while 13 were referred from other institutions. Between 1985 and 1989 the incidence of injuries per total hospital admissions at risk increased from 4 to 11 per 10,000 (p = 0.0067), the incidence of urological injuries increased from 4 to 23 per 10,000 (p = 0.0071) and the incidence of injuries occurring in gynecologic patients increased from 13 to 41 per 10,000 admissions (p = 0.0385). There was no difference in the incidence of injuries in the general surgical population. From 1980 to 1984 no laparoscopic or ureteroscopic injuries occurred. However, from 1985 to 1989, 25% of gynecologic injuries occurred during laparoscopy and 70% of urological injuries were sustained during ureteroscopic procedures. Depending on the extent of the injury, patients were initially treated with either endourological or open surgical procedures. Good results were obtained in the majority of cases. Contemporary therapeutic strategies for treating patients sustaining ureteral injuries are discussed.

Female↗

PubMed1994

Incidence of renal anomalies in children prenatally exposed to ethanol.

OBJECTIVE: Based on a number of studies involving animals as well as human case reports indicating an association between prenatal ethanol exposure and renal malformations, it has been suggested that children with fetal alcohol syndrome (FAS) should be screened for renal anomalies. The purpose of this study was to evaluate a group of children prenatally exposed to alcohol to determine the incidence of renal anomalies and to evaluate the need for such a screening procedure. METHODS: Renal ultrasounds were performed on a total of 84 patients (68 children, 13 adolescents, and three adults). In addition to screening for malformations, renal size was studied. Data were analyzed using both chronologic and height-age as determinants of kidney size. PATIENTS: Of these 84 patients, 51 (61%) had FAS, and 33 (39%) had a history of prenatal ethanol exposure but did not have FAS. RESULTS: Three (3.6%) patients (one with FAS, two with prenatal ethanol exposure who did not have FAS) had significant renal abnormalities. This incidence was not significantly different from that found in ultrasound screening of newborns. The kidneys of children with both FAS and prenatal ethanol exposure who did not have FAS were significantly smaller than normal for both chronologic and height-age. When children were compared across chronologic ages, those with FAS had significantly smaller kidneys than those who had no evidence of FAS. After adjusting for height, the difference between these two groups was no longer significant. CONCLUSIONS: Based on these data, children prenatally exposed to ethanol do not need to be screened for renal anomalies.

Abnormalities, Drug-Induced↗

PubMed1993

A homoallelic Gly317-->Asp mutation in ALPL causes the perinatal (lethal) form of hypophosphatasia in Canadian mennonites.

We have discovered a single homoallelic nucleotide substitution as the putative cause of the perinatal (lethal) form of hypophosphatasia in Canadian Mennonites. Previous linkage and haplotype analysis in this population suggested that a single mutational event was responsible for this autosomal recessive form of hypophosphatasia. The mutation is a guanosine-to-adenosine substitution at nucleotide position 1177 in exon 10 of the tissue nonspecific (liver/bone/kidney) alkaline phosphatase gene. This Gly317-->Asp mutation segregates exclusively with the heterozygote phenotype we previously assigned by biochemical testing (maximum combined lod score of 18.24 at theta = 0.00). This putative disease-causing mutation has not been described in controls nor in other non-Mennonite probands with both lethal and nonlethal forms of hypophosphatasia studied to date. This Gly317-->Asp mutation changes a polar glycine to an acidic aspartate at amino acid position 317 within the highly conserved active site region of the 507-amino-acid polypeptide. Carrier screening for this lethal mutation in our high-risk population is now feasible.

Alkaline Phosphatase↗

PubMed1993

Doppler hemodynamic profiles of 82 clinically and echocardiographically normal tricuspid valve prostheses.

BACKGROUND: Normal Doppler hemodynamics for tricuspid prostheses have not been well characterized in a large group of patients. Therefore, we analyzed comprehensive Doppler echocardiographic examinations of 82 patients with tricuspid prostheses that were normal by clinical and two-dimensional echocardiographic examinations to establish the normal hemodynamics of various types and sizes of tricuspid prostheses. METHODS AND RESULTS: The earliest complete postoperative echocardiographic study from each patient was chosen for analysis. Doppler examinations were analyzed on an off-line station from tapes or Doppler strip charts. Early velocity, atrial velocity, end-diastolic velocity, pressure half-time, and mean gradient were obtained by digitizing tricuspid velocity curves. The incidence of "physiological" tricuspid prosthetic regurgitation was noted. Ten Doppler cycles were measured for each patient, and maximal, minimal, and average measurements were recorded. The mean values +/- SD of early velocity, atrial velocity, end-diastolic velocity, mean gradient, and pressure half-time and incidence of mild prosthetic regurgitation were reported for each type of prosthesis, as were highest Doppler measurements for each valve type. Average pressure half-time was significantly lower for St Jude than for heterograft prostheses (P = .04). There were no significant differences between the valve types for mean gradient, early velocity, or incidence of prosthetic regurgitation. Increasing prosthesis size was associated with lower average pressure half-time for heterograft prostheses (P = .024). Average differences (respiratory- and cycle-length-dependent) between maximal and minimal values for 10 cardiac cycles were established for each prosthesis. CONCLUSIONS: This study establishes normal ranges for Doppler hemodynamics of various tricuspid prostheses and emphasizes the importance of measuring multiple cycles for each tricuspid prosthesis, regardless of cardiac rhythm.

Adolescent↗

PubMed1993

Myelitis following chickenpox: a case report.

An 18-year-old woman presented with myelopathic symptoms and a T-8 sensory deficit during a primary varicella infection. There were significant MRI changes in both the cervical and thoracic regions. Following treatment with steroids and intravenous acyclovir, the patient improved clinically and the abnormalities on MRI improved.

Adolescent↗

PubMed1993

Ocular tilt reaction resulting from vestibuloacoustic nerve surgery.

The ocular tilt reaction (OTR) is a triad of head-eye synkinesis composed of head tilt, conjugate ocular torsion in the direction of head tilt, and skew deviation. The OTR represents a normal compensatory response to lateral head tilts and is produced by activation of the utricle of the lowermost ear. A pathological OTR results when otolith activity is unopposed as the result of injury to the opposite utricle or its nerve. Vertical diplopia may be the only symptom of OTR in patients who have undergone surgery involving the vestibuloacoustic nerve. We report a series of patients with OTR after surgery for acoustic neuroma or Meniere's disease. In each patient, the manifesting symptom was vertical diplopia. Bedside neuro-ophthalmological testing readily excluded a brain stem cause for the double vision. We conclude that OTR after vestibuloacoustic surgery is a benign condition with spontaneous resolution of symptoms within several months.

Auditory Pathways↗

PubMed1992

HIV prevention: a dramaturgical analysis and practical guide to creating safer sex interventions.

Safer sex is currently a major strategy for preventing HIV transmission. We examine safer sex interventions using an interactionist form of dramaturgical analysis. This approach yields a dynamic model with which to generate novel safer sex interventions highly sensitive to changing individual, cultural, and social variables. Our goal is to help medical anthropologists, applied social scientists, health educators, community outreach specialists, and those who are sexually active apply safer sex strategies more effectively.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Measurement of globe position in complex orbital fractures. I. A modification of Hertel's exophthalmometer, using the external auditory canal as a reference point.

Where there has been displacement or removal of the lateral orbital rim or zygomaticomaxillary complex secondary to trauma or surgery, the measure of globe position by the Hertel exophthalmometer is problematic and inaccurate. A modification of Hertel's instrument that uses the external auditory canal (EAC) rather than the orbital rim as reference point has been developed. Measurement of globe position of 120 normal volunteers was obtained with the Hertel and the modified EAC-fixated exophthalmometer. Although the mean absolute difference between right and left measurements for both methods (Hertel mean, 0.36 mm; modified mean, 0.51 mm; n = 120) differed statistically from 0 (p = 0.0001), that difference was not clinically significant. A more meaningful comparison was that of the variability of the two methods. The variance of the Hertel method (0.32) did not differ from the variance of the modified method (0.40; p = 0.06). No statistically significant difference was noted for sex (p = 0.33) or for race (p = 0.11). We believe this instrument to be of practical use in the assessment of enophthalmos or exophthalmos in patients whose facial deformity, trauma, surgery, or disease precludes the use of a rim-based exophthalmometry.

Ear Canal↗

PubMed1992

Regional cerebrovascular responses to progressive hypotension after traumatic brain injury in cats.

We investigated the effects of hypotension on cerebral blood flow (CBF) after traumatic brain injury (TBI) in cats. Isoflurane-anesthetized cats were prepared for TBI and for microsphere measurements of total (T) and regional (r) CBF. Four groups were studied: sham injury (group I, n = 6); TBI (group II, n = 6); isoflurane anesthesia, no TBI or hypotension (group III, n = 4); and isoflurane and TBI, no hypotension (group IV, n = 8). After TBI or sham trauma, mean arterial pressure (MAP) was reduced to 80, 60, and 40 mmHg by hemorrhage. Group I TCBF did not change significantly from baseline until MAP reached 40 mmHg, but rCBF was more dependent on MAP in anterior hemispheric than in brain stem regions. Group II TCBF was significantly lower than baseline, and group I TCBF at all levels of hypotension and autoregulation was impaired at higher MAP levels in anterior than in posterior brain regions. Groups III and IV indicated that decreases in TCBF were not due to duration of the preparation or to TBI in the absence of hemorrhagic hypotension. We conclude that global and regional autoregulation are absent in response to hemorrhagic hypotension after TBI.

Anesthesia↗

PubMed1992

Reduced cerebral blood flow, oxygen delivery, and electroencephalographic activity after traumatic brain injury and mild hemorrhage in cats.

The authors investigated the effects of transient, mild hemorrhagic hypotension after fluid-percussion traumatic brain injury on intracranial pressure, cerebral blood flow (CBF), cerebral oxygen delivery (CBF x arterial O2 content), and electroencephalographic (EEG) activity. Adult mongrel cats were anesthetized with 1.6% isoflurane in N2O:O2 (70:30) and prepared for trauma and for radioactive microsphere CBF measurement. Isoflurane concentration was decreased to 0.8%, and the cats were randomly assigned to one of four control groups or to an experimental group. Animals in the four control groups underwent either mild hemorrhage (18 ml.kg-1) immediately followed by resuscitation with equal volumes of 10% Hetastarch (eight cats), mild hemorrhage followed by replacement of shed blood (six cats), isovolemic hemodilution with 18 ml.kg-1 of Hetastarch (six cats), or moderate (2.2 atm) trauma alone (eight cats). The experimental group received a combination of trauma and mild hemorrhage followed by resuscitation with Hetastarch (eight cats). Mild hemorrhage produced no significant changes in CBF, renal blood flow, or cardiac output. Following resuscitation from mild hemorrhage, mean arterial blood pressure, cardiac output, renal blood flow, and CBF were not significantly different from baseline; cardiac output and renal blood flow did not differ significantly from baseline 2 hours after Hetastarch resuscitation. Neither hemorrhage nor trauma alone produced significant decreases in CBF or in EEG activity, but trauma followed by hemorrhage and resuscitation produced significant (p less than 0.01) decreases in CBF, cerebral oxygen delivery, and EEG score. These data demonstrate that, following traumatic brain injury, even mild hemorrhagic hypotension is associated with significant deficits in cerebral oxygen availability and neurological function.

Animals↗

PubMed1992

Cerebrovascular and cerebral metabolic effects of alterations in perfusion flow rate during hypothermic cardiopulmonary bypass in man.

Recent experimental and clinical investigations provide conflicting evidence regarding the effects of changes in the systemic flow rate from the pump oxygenator on cerebral blood flow and the cerebral metabolic rate of oxygen consumption. However, the results of existing clinical studies are difficult to interpret because of the confounding effects of differences in management of arterial carbon dioxide tension and use of anesthetic and vasoactive agents during cardiopulmonary bypass. To clarify the relationship among perfusion flow rate, cerebral blood flow, and cerebral metabolic rate of oxygen consumption in man during hypothermic cardiopulmonary bypass, we varied perfusion flow rate in random order to either 1.75 or 2.25 L.min-1.m-2 and studied cerebral blood flow (measured by clearance of xenon 133) and cerebral metabolic rate of oxygen consumption (estimated as the product of cerebral blood flow and the cerebral arteriovenous oxygen content difference) in patients managed with both the alpha-stat (group 1) and the pH-stat (group 2) methods of pH and arterial carbon dioxide tension adjustment. We measured the cerebral arteriovenous oxygen content difference using radial arterial and jugular venous bulb blood samples. In each patient other variables known to exert effects on cerebral blood flow and cerebral metabolic rate of oxygen consumption, including temperature, arterial carbon dioxide tension, arterial oxygen tension, mean arterial pressure, and hematocrit, were maintained constant between measurements. In both groups, mean arterial pressure at both pump flow rates was similar because of spontaneous reciprocal alterations in systemic vascular resistance, that is, as perfusion flow rate declined, systemic vascular resistance increased; as perfusion flow rate increased, systemic vascular resistance declined. Under these tightly controlled conditions, pump flow variation per se exerted no effect on cerebral blood flow or cerebral metabolic rate of oxygen consumption in either group.

Blood Flow Velocity↗

PubMed1991

Improved lung preservation with cold air storage.

Conventional topical slush cooling limits lung transport to 4 to 6 hours. For this canine study of an alternate air cooling system, 37 canine lungs were removed: 24 were placed in plastic bags, and inserted in a Transplanthermm container at core air temperatures (n = 6 lungs each) of (A) 4 degrees C, (B) 8 degrees C, (C) 12 degrees C, and (D) 20 degrees C; 6 were stored conventionally in ice slush (E); and 7 were transplanted immediately (F). After 8 hours, the stored lungs were transplanted and the contralateral pulmonary artery was ligated. Survival, arterial oxygen tension, and extravascular lung water were monitored at 15 minutes and every hour for 4 hours. Four-hour survival was 100% in groups A, B, and F; 83% in group C, 50% in group D, and 17% in group E. The mean arterial oxygen tension at 1 hour was lower in group E (6.4 +/- 2.4 kPa) than in group A (39.8 +/- 13.2 kPa) (p = 0.0002) or in group F (42.0 +/- 16.2 kPa) (p = 0.0035). Extravascular lung water in group E was higher at 15 minutes (15.44 +/- 5.63 mL/kg) than in group A (3.76 +/- 0.63 mL/kg) (p = 0.0001) and group F (4.69 +/- 1.65 mL/kg) (p = 0.003). Cold air storage appears to provide better lung preservation than hypothermic immersion in ice slush.

Air↗

PubMed1991

A comparison of anatrophic nephrolithotomy and percutaneous nephrolithotomy with and without extracorporeal shock wave lithotripsy for management of patients with staghorn calculi.

A retrospective study was conducted comparing anatrophic nephrolithotomy (10 cases), percutaneous nephrolithotomy alone (4 cases) or percutaneous nephrolithotomy combined with extracorporeal shock wave lithotripsy (23 cases) for the treatment of large staghorn calculi. A comparison based on collecting system anatomy demonstrated that anatrophic nephrolithotomy resulted in a greater stone-free rate, shorter hospitalization and lower costs while complication rates were similar. Anatrophic nephrolithotomy should still be considered a viable treatment option, especially for patients with large branched calculi in complex collecting systems.

Adult↗

PubMed1991

Sodium nitroprusside infusion does not dilate cerebral resistance vessels during hypothermic cardiopulmonary bypass.

This study determined whether sodium nitroprusside (SNP) changes cerebral vascular resistance during stable, hypothermic cardiopulmonary bypass (CPB). Cerebral blood flow (CBF) was measured using Xenon clearance in 39 patients anesthetized with fentanyl. In 25 patients (group 1), CBF was measured before and during infusion of SNP at a rate sufficient to reduce mean arterial pressure (MAP) approximately 20%. In 14 other patients (group 2), CBF was measured before and during simultaneous infusion of SNP and phenylephrine; SNP was continued at a rate that had reduced MAP approximately 20% while phenylephrine was added in a dose sufficient to restore MAP to preinfusion levels. Patients within each group were randomized to maintenance of PaCO2 approximately 40 mmHg (groups 1a and 2a), uncorrected for body temperature, or to maintenance of PaCO2 approximately 50 mmHg (groups 1b and 2b). The following variables were maintained within a narrow range: nasopharyngeal temperature (26-29 degrees C), pump oxygenator flow (1.7-2.5 l.min-1.m-2), PaO2 (150-300 mmHg), and Hct (22-28 vol%). In each patient, controlled variables varied no more than +/- 5% between measurements. In group 1a (PaCO2 approximately 40 mmHg), MAP was 86 +/- 9 mmHg (mean +/- SD) before and 65 +/- 8 mmHg during SNP infusion (P less than 0.0001). CBF was 12 +/- 3 ml.100g-1.min-1 before and 10 +/- 2 ml.100(-1).min-1 during SNP infusion (P less than 0.01). In group 1b (PaCO2 approximately 55 mmHg), MAP was 86 +/- 11 mmHg before and 66 +/- 13 mmHg during SNP infusion (P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗