Biomedical subjects

D A Girod

Publications and source records attributed to D A Girod.

At least 19 recordsLinked to original sources

PubMed2002

Resolution of acquired pulmonary arteriovenous malformations in a patient with total anomalous systemic venous return.

An 11-year-old male with total anomalous systemic venous return had surgical repair except for the hepatic venous return, which drained to the left atrium. He developed progressive cyanosis and fatigue and was diagnosed with large pulmonary arteriovenous malformations (PAVMs) during cardiac catheterization with the use of bubble contrast echocardiography. After surgical redirection of hepatic venous flow to the right heart and pulmonary arterial system, resolution of these PAVMs was demonstrated clinically and by contrast echocardiography. This unique case report demonstrates the development of PAVMs with exclusion of hepatic venous return through the pulmonary vascular bed while pulsatile pulmonary blood flow remains intact. It reinforces the likelihood of the absence of an as yet unidentified hepatic vasoactive substance as the source for development of PAVMs.

Arteriovenous Malformations↗

PubMed2001

Correlation of expression of cyclooxygenase-2, vascular endothelial growth factor, and peroxisome proliferator-activated receptor delta with head and neck squamous cell carcinoma.

Cyclooxygenase (COX) is the rate-limiting enzyme in the formation of prostaglandins from arachidonic acid. COX exists in 2 isoforms, COX-1 and COX-2. These isoforms are encoded by separate genes and demonstrate cell-specific expression and regulation. Peroxisome proliferator-activated receptor delta (PPARdelta) is a nuclear transcription factor that is activated by prostacyclin. Vascular endothelial growth factor (VEGF) is a proangiogenic factor that is up-regulated in various tumors. Vascular endothelial growth factor has been shown to interact with COX-derived prostaglandins in angiogenesis. To better understand the roles of these genes in head and neck squamous cell carcinoma (HNSCCA), we examined the differential expression of the COX1, COX2, VEGF, and PPARdelta genes in these tumors. Tissue samples from patients with HNSCCA were analyzed for COX-1, COX-2, VEGF, and PPARdelta messenger RNAs (mRNAs) by in situ hybridization. COX-1 and COX-2 mRNAs were also evaluated with Northern blot hybridization. Immunohistochemistry was used to analyze for COX-2 and PPARdelta proteins. Results showed focal areas of accumulation for COX-2, VEGF, and PPARdelta but not COX-1 in human HNSCCA. Northern blot hybridization showed higher levels of COX-2 mRNA in HNSCCA than in normal tissue. This suggests a supportive role of COX-2 in development and/or progression of HNSCCA. In addition, PPARdelta may be a receptor for COX-2-produced prostaglandins in HNSCCA. There is a potential role for selective COX-2 inhibitors in the treatment of these lesions.

Blotting, Northern↗

PubMed2000

Central nervous system plasticity during hair cell loss and regeneration.

Following cochlear ablation, auditory neurons in the central nervous system (CNS) undergo alterations in morphology and function, including neuronal cell death. The trigger for these CNS changes is the abrupt cessation of afferent input via eighth nerve fiber activity. Gentamicin can cause ototoxic damage to cochlear hair cells responsible for high frequency hearing, which seems likely to cause a frequency-specific loss of input into the CNS. In birds, these hair cells can regenerate, presumably restoring input into the CNS. This review summarizes current knowledge of how CNS auditory neurons respond to this transient, frequency-specific loss of cochlear function. A single systemic injection of a high dose of gentamicin results in the complete loss of high frequency hair cells by 5 days, followed by the regeneration of new hair cells. Both hair cell-specific functional measures and estimates of CNS afferent activity suggest that newly regenerated hair cells restore afferent input to brainstem auditory neurons. Frequency-specific neuronal cell death and shrinkage occur following gentamicin damage to hair cells, with an unexpected recovery of neuronal cell number at longer survival times. A newly-developed method for topical, unilateral gentamicin application will allow future studies to compare neuronal changes within a given animal.

Animals↗

PubMed2000

Torsional strength of the radius after osteofasciocutaneous free flap harvest with and without primary bone plating.

The osteocutaneous radial forearm free flap (OCRFFF) has not gained widespread popularity in mandibular reconstruction, primarily because of concerns about pathologic fracture of the weakened radius. This study examines the effectiveness of plate fixation of the radius bone after harvest of the OCRFFF as a mechanism to minimize donor-site morbidity and increase the usefulness of the OCRFFF. Matched pairs of fresh human cadaveric radius bones were used in this study. Two study groups were designed. The first group was used to define the amount of strength lost after a typical bone graft harvest. The second group was designed to demonstrate how much torsional strength was regained by the application of an orthopedic reconstruction plate. Statistically significant results were obtained for both groups. In group 1, the strength of the cut bones compared with that of the unaltered bones was significantly decreased by 82% (P = 0.016). In group 2, the cut bones reinforced with a plate were 75% stronger (P = 0.002) than the bones that were only cut. Although the radius bone is significantly weakened by the harvest of a graft, much of this strength can be regained with plate fixation of the radius.

Biomechanical Phenomena↗

PubMed2000

Preoperative evaluation of the radial forearm free flap patient with the objective Allen's test.

OBJECTIVE: The conventional subjective Allen's test (SAT) can be problematic because of its subjective nature. The objective Allen's test (OAT) was used before surgery to reliably and objectively assess forearm vascular flow in anticipation of harvesting a radial forearm free flap (RFFF) for use in head and neck reconstruction. STUDY DESIGN AND SETTING: Retrospective analysis of 65 patients undergoing both preoperative SAT and OAT was completed at the University of Kansas Medical Center between December 1994 and March 1998. RESULTS: The sensitivity and specificity of the SAT compared with the sensitivity and specificity of the OAT were only 65% and 76%, respectively. In 40 patients with at least 1 forearm with a positive SAT, only 1 (2.5%) patient was found by OAT to have vasculature that would not have allowed safe RFFF harvest in either forearm. In contrast, of the 25 patients with equivocal or negative SAT results in both arms, 18 (72%) were found by OAT to be safe candidates for RFFF harvests. CONCLUSIONS: The OAT is an objective measure of forearm vascular flow and is superior to conventional SAT in RFFF donor-site selection.

Adult↗

PubMed2000

Osteocutaneous radial forearm free flap: its use without significant donor site morbidity.

While the fasciocutaneous radial forearm free flap has gained increasing popularity, the osteocutaneous radial forearm free flap has been condemned because of a high rate of pathologic donor radius fracture. On the basis of studies that demonstrated increased strength in ostectomized radii after dynamic compression plating, we believed that internal fixation at the time of graft harvest would significantly reduce the incidence of donor radius fracture. This is a retrospective review of the first 54 patients undergoing osteocutaneous radial forearm free flap reconstruction of the head and neck at our institution; 52 underwent prophylactic plating of their donor radii. No clinically significant donor radius fractures have occurred in plated patients. Five asymptomatic fractures were discovered on routine radiographs and required no treatment. Objective evaluation of forearm range of motion and strength after graft harvest demonstrated excellent function compared with unoperated arms. Serial radiographs have shown remodeling and reconstitution of donor radii without localized osteopenia.

Adolescent↗

PubMed2000

Osteocutaneous radial forearm free flaps. The necessity of internal fixation of the donor-site defect to prevent pathological fracture.

BACKGROUND: Osteocutaneous radial forearm free flaps have fallen from favor due to pathological fractures of the radius. The purposes of this study were to propose a means to decrease the rate of pathological fracture by prophylactic fixation of the donor-site defect and to evaluate this technique biomechanically. METHODS: Two groups of ten matched pairs of fresh-frozen cadaveric radii were harvested. In Group 1, an eight-centimeter length of radius comprising 50 percent of the cross-sectional area of the bone was removed to simulate an osteocutaneous radial forearm donor-site defect. This defect was created in one member of each pair, with the other bone in the pair left intact. In Group 2, both members of the ten matched pairs of radii had identical defects created as previously described. However, one radius in each pair had a twelve-hole, 3.5-millimeter dynamic compression plate placed across the segmental defect. In each group, five matched pairs were tested to failure in torsion and five matched pairs were tested to failure in four-point bending. RESULTS: In Group 1, the intact radius was a mean of 5.7 times stronger in torsion and 4.2 times stronger in four-point bending than the radius with the segmental resection. In Group 2, the radius that was ostectomized and fixed with a plate was a mean of 4.0 times stronger in torsion and 2.7 times stronger in four-point bending than the ostectomized radius. CONCLUSIONS: Removal of an eight-centimeter segment from the radius dramatically decreased both torsion and bending strength. Application of a plate over the defect in the radius significantly restored the strength of the radius (p = 0.01).

Biomechanical Phenomena↗

PubMed1999

Venous valves in the neck: implications for microvascular free flap reconstruction.

Successful microvascular free flap reconstruction requires adequate arterial inflow and venous outflow. We report 4 cases that demonstrate the not uncommon occurrence of locating valves in veins during microvascular head and neck reconstructive procedures. Failure to recognize these valves could have compromised the venous anastomosis. The anatomical literature states that veins in the head and neck lack valves, allowing bidirectional blood flow. As a result, there is potential significant flexibility in the selection of recipient veins for the microvascular anastomosis during free flap reconstruction. The unrecognized presence of a venous valve, however, could cause thrombosis of the venous anastomosis and, ultimately, flap failure. This report of venous valves should speak caution to the head and neck microvascular surgeon when he or she is selecting recipient veins in the neck.

Head↗

PubMed1999

Tonotopic changes in 2-deoxyglucose activity in chick cochlear nucleus during hair cell loss and regeneration.

Following cochlear ablation, auditory neurons in the central nervous system (CNS) undergo alterations in morphology and function, including neuronal cell death. The trigger for these CNS changes is the abrupt cessation of eighth nerve fiber activity. Gentamicin can cause ototoxic damage to cochlear hair cells responsible for high frequency hearing. In birds, these hair cells can regenerate. Therefore, gentamicin causes a partial, yet reversible insult to the ear. It is not known how this partial hair cell damage affects excitatory input to the cochlear nucleus. We examined chick cochlear nucleus activity during hair cell loss and regeneration by measuring 2-deoxyglucose (2DG) uptake. Normal animals showed a rostral to caudal gradient of 2DG activity, with higher activity in caudal regions. When hair cells are damaged (2, 5 days), 2DG uptake is decreased in cochlear nucleus. When hair cells regenerate (9, 16, 28 days), 2DG uptake returns to control levels. This decrease and subsequent return of activity only occurs in the rostral, high frequency region of the cochlear nucleus. No changes are seen in the caudal, low frequency region. These results suggest that changes in activity of cochlear nucleus occur at a similar time course to anatomical changes in the cochlea.

Acoustic Stimulation↗

PubMed1998

Retrieval of "old" foreign bodies from the cardiovascular system in children.

Several techniques have been developed to retrieve catheter and guide wire fragments that have embolized to the heart and pulmonary vasculature. In most instances, retrieval of the embolized fragments is performed soon after the event has occurred. In this report, we summarize our experience with the removal of these fragments in 3 children after a significant amount of time had elapsed since the time of embolization. The embolized catheter and guide wire fragments were removed without any complications. We also describe the techniques used for their removal, and the problems encountered during the removal of these "old" foreign bodies.

Adolescent↗

PubMed1998

Round window administration of gentamicin: a new method for the study of ototoxicity of cochlear hair cells.

Damage to inner ear sensory hair cells after systemic administration of ototoxic drugs has been documented in humans and animals. Birds have the ability to regenerate new hair cells to replace those damaged by drugs or noise. Unfortunately, the systemic administration of gentamicin damages both ears in a variable fashion with potentially confounding systemic drug effects. We developed a method of direct application of gentamicin to one cochlea of hatchling chickens, allowing the other ear to serve as a within-animal control. We tested variables including the vehicle for application, location of application, dosage, and duration of gentamicin exposure. After 5 or 28 days survival, the percent length damage to the cochlea and regeneration of hair cells was evaluated using scanning electron microscopy. Controls consisted of the opposite unexposed cochlea and additional animals which received saline instead of gentamicin. Excellent damage was achieved using gentamicin-soaked Gelfoam pledgets applied to the round window membrane. The percent length damage could be varied from 15 to 100% by changing the dosage of gentamicin, with exposures as short as 30 min. No damage was observed in control animals. Regeneration of hair cells was observed in both the base and apex by 28 days survival.

Animals↗

PubMed1998

Evidence for loss and recovery of chick brainstem auditory neurons during gentamicin-induced cochlear damage and regeneration.

It is well documented that damage to the chick cochlea caused by acoustic overstimulation or ototoxic drugs is reversible. Second-order auditory neurons in nucleus magnocellularis (NM) are sensitive to changes in input from the cochlea. However, few experiments studying changes in NM during cochlear hair cell loss and regeneration have been reported. Chicks were given a single systemic dose of gentamicin, which results in maximal hair cell loss in the base of the cochlea after 5 days. Many new hair cells are present by 9 days. These new hair cells are mature but not completely recovered in organization by 70 days. We counted neurons in Nissl-stained sections of the brainstem within specific tonotopic regions of NM, comparing absolute cell number between gentamicin- and saline-treated animals at both short and long survival times. Our data suggest that neuronal number in rostral NM parallels hair cell number in the base of the cochlea. That is, after a single dose of gentamicin, we see a loss of both cochlear hair cells and NM neurons early, followed by a recovery of both cochlear hair cells and NM neurons later. These results suggest that neurons, like cochlear hair cells, can recover following gentamicin-induced damage.

Animals↗

PubMed1998

First report of Hürthle cell carcinoma revealed by octreotide scanning.

Octreotide is an 8-chain amino acid analog of somatostatin. Somatostatin and its receptors occur naturally in multiple sites within the body and serve a suppressive role in endocrine hormone release. When octreotide, which has a considerably longer half-life than somatostatin, is combined with a radioactive isotope, receptor-based imaging can be performed to visualize tumors with high concentrations of somatostatin receptors. Tumors of neural crest origin -- pituitary adenomas, islet cell tumors, medullary thyroid carcinomas, pheochromocytomas, carcinoids, and paragangliomas -- all express high levels of somatostatin receptors. We present the first reported positive octreotide scan of a Hürthle cell carcinoma of the thyroid and, more important, discuss the role of octreotide scanning in otolaryngology, which has not yet been reviewed by our literature.

Adenocarcinoma↗

PubMed1997

Third branchial anomalies. Avoiding recurrences.

Lateral cervical cysts, sinuses, and fistulas have been described as anomalies of the normal development of the branchial apparatus. Third branchial apparatus anomalies are rare and constitute less than 1% of all such cases. Three cases of third branchial cleft cysts and sinus tracts are presented. Two patients had previously undergone multiple attempts at extirpation. Complete removal of recurrent branchial anomalies is difficult because of scarring and fascial plane disruption. Recurrences were often the result of inadequate excision, possibly of the tract communicating with the piriform sinus. To avoid this we advocate endoscopy prior to initial resection of a suspected branchial cleft anomaly to identify any pharyngeal communication. A combined, simultaneous endoscopic identification of the piriform sinus tract with a lateral external cervical dissection facilitates complete resection. In recurrent cases, wide-field extirpation of the cyst, tract, and scar tissue is necessary to ensure complete removal of the branchial cleft anomaly. A review of the literature and of branchial apparatus embryology is also presented.

Adolescent↗

PubMed1997

Risk factors for pulmonary complications in the postoperative head and neck surgery patient.

BACKGROUND: Pulmonary complications are a primary source of increased cost and morbidity in surgically treated head and neck cancer patients. This study investigates potential risk factors related to postoperative pulmonary complications (pneumonia, adult respiratory distress syndrome (ARDS), and prolonged mechanical ventilation) in head and neck cancer patients. METHODS: Data from 144 major head and neck procedures performed at the University of Washington between 1985 and 1991 were retrospectively reviewed. Univariate and multivariate analysis were used to evaluate preoperative and perioperative variables identified as potential risk factors for postoperative pulmonary complications. RESULTS: Fifteen percent of patients had a postoperative pulmonary complication, (n = 21: 18 postoperative pneumonia; 2 ARDS; and 4 prolonged ventilation). The most common pneumonia pathogen was Staphylococcus aureus (62%). Univariate analysis identified smoking and weight loss as significant factors associated with pulmonary complications. The variables preoperative blood urea nitrogen, white blood cell count, and operative chest flap closure all approached but did not reach significance. Multivariate analysis of a subgroup of patients identified smoking history and perioperative antibiotic choice as the only independently significant variables. CONCLUSIONS: Patient smoking history was the primary variable related to postoperative pulmonary problems, with evidence of increasing risk with increased exposure. Other variables added only limited additional risk association information after multivariate analysis.

Analysis of Variance↗

PubMed1996

Surgical management of total anomalous pulmonary venous connection. Thirty-year trends.

BACKGROUND: Reports of surgical correction of total anomalous pulmonary venous connection (TAPVC) over the past 30 years indicate a general improvement in operative survival. However, prevention of late pulmonary venous obstruction continues to be a cornerstone of successful repair. The purpose of the study was to identify factors associated with improvement in perioperative mortality and to determine risk factors for death and reoperation due to pulmonary vein stenosis after repair of TAPVC. METHODS AND RESULTS: Using univariate and multiple regression analysis, we analyzed risk of early and late mortality and need for reoperation in 105 patients operated on between April 1966 and June 1995. Despite increased frequency of neonatal repair in the most recent time period (29% in 1966 through 1985; 55% in 1991 through 1995, P < .05), operative mortality declined (13% in 1966 through 1985; 0% in 1991 through 1995). The incidence of postoperative pulmonary hypertensive episodes and death related to pulmonary hypertension decreased significantly over the study period (P < .001). Aggressive preoperative elective medical stabilization and prophylaxis of postoperative pulmonary hypertensive episodes may have contributed to this improvement. By univariate analysis, preoperative pulmonary hypertension (P < .02) and preoperative pulmonary vein obstruction (P < .01) correlated with early mortality up to 1990 but not in the past 5 years. Multiple logistic regression analysis showed that only a small pulmonary confluence associated with diffuse pulmonary vein stenosis was an independent risk factor for early (P < .001) and late (P = .01) death as well as need for reoperation (P = .007). Type of TAPVC was not a significant risk factor throughout the three decades of our experience. At a median follow-up of 87 months, late survival was 98% (93 of 95 operative survivors), and all are NYHA class I. CONCLUSIONS: Improvements on surgical technique as well as preoperative and postoperative management account for the reduction in mortality and need for reoperation for most types of TAPVC. However, the presence of a small venous confluence and diffuse pulmonary vein stenosis remains a risk factor for adverse outcome.

Cardiac Surgical Procedures↗

PubMed1996

Right ventricular systolic function in adolescents and young adults after Mustard operation for transposition of the great arteries.

This study evaluates long-term ( > 10 years since surgery) right ventricular (RV) systolic function in patients who had previously undergone intraatrial baffle surgery for transposition of the great arteries. Studies suggest these patients are clinically stable and lead satisfactory lifestyles, but long-term ventricular performance is not known. Radionuclide angiocardiography was used to estimate RV ejection fraction in 58 patients a mean of 14 years after the Mustard operation. Repeat studies were performed in 32 patients. The absolute RV ejection fraction of 0.53 +/- 0.10 in our patients did not differ from normal values. Nine patients had a value < 0.42, placing them > 2 SDs below normal. Repeat RV ejection fraction decreased from 0.54 +/- 0.11 to 0.51 +/- 0.11 (p < 0.1) in 32 patients, and > 0.10 in 6. Thus, RV ejection fraction was abnormal in 9 of 58 patients (16%) evaluated > 10 years after a Mustard operation. Repeat studies demonstrate worsening in at least 6 of 32 patients (19%). These postoperative Mustard patients require continued evaluation, even in the absence of overt symptomatology.

Adolescent↗

PubMed1995

Effect of local epinephrine on cutaneous bloodflow in the human neck.

The effectiveness of local anesthetics is improved by the addition of a vasoconstrictor which increases duration of action and decreases both systemic toxic reactions and local bleeding. Epinephrine, the standard drug for vasoconstriction, has some limitations due to potential dose-related cardiac and local toxic effects. The authors examined the minimal effective epinephrine concentration required for maximal cutaneous vasoconstriction in the human subject so as to limit potential dose-related side effects. In a randomized, double-blinded prospective study, 23 patients undergoing head and neck surgical procedures under general anesthesia were enrolled to quantify the effect of subdermal infiltration of 1% lidocaine with epinephrine at varying concentrations on local cutaneous bloodflow utilizing laser Doppler flowmetry. A comparison of the onset of vasoconstriction and magnitude of diminished bloodflow was made for several commonly used concentrations of epinephrine, with 1% lidocaine and normal saline serving as controls. There were no significant differences (P > .05) between epinephrine concentrations of 1:400,000, 1:200,000, 1:100,000, and 1:50,000 when examining onset and magnitude of vasoconstriction.

Anesthesia, General↗