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Biomedical subjects

K Wolfe

Publications and source records attributed to K Wolfe.

At least 19 recordsLinked to original sources
PubMed2005

GLUT-1: an extra diagnostic tool to differentiate between haemangiomas and vascular malformations.

The differential diagnosis between juvenile haemangiomas, vascular malformations, pyogenic granulomas and normally proliferative endothelium (granulation tissue) on the basis of histology alone is sometimes difficult. This is important because haemangiomas, are self-limiting and vascular malformations are not. We report our experience of using the immunohistochemical marker GLUT-1 to distinguish haemangiomas from vascular malformations following the initial report by North and Colleagues (1998). We studied a total of 50 specimens from patients with vascular anomalies, and found that GLUT-1 reactivity was positive in 18 out of 19 juvenile haemangiomas, negative in two out of two noninvoluting congenital haemangiomas (NICH) and negative in 29 out of 29 vascular malformations, that included capillary malformations, lymphatic malformations, venous malformations and arteriovenous malformations (95% sensitivity, 100% specificity). Pyogenic granulomas (n = 4) and granulation tissue samples (n = 4) were used as negative controls. Placenta tissue was used as positive control. GLUT-1 accurately distinguishes haemangiomas from vascular malformations, and as a result from this work, we use this technique in routine histopathological differentiation of vascular anomalies.

Biomarkers, Tumor↗
PubMed2000

Tall cell variant: an aggressive form of papillary thyroid carcinoma.

Twenty-four cases of the tall cell variant (TCV), a subset of papillary thyroid carcinoma, were identified in a group of 624 patients with thyroid cancer. All pathology specimens were reviewed, and each patient's carcinoma was categorized according to characteristics on presentation, local recurrence, distant metastases, follow-up, and tumor-related mortality. The TCV group was compared with a historical control group (Mazzaferri and Jhiang: 1355 patients). The TCV group had a statistically higher percentage of stage 3 and 4 carcinoma, extrathyroidal invasion, and tumor size less than 1.5 cm than the control group. There was no statistical relationship between age greater than 50 years and stage in the TCV group. No relationship could be found between TCV histology and recurrence or mortality. These findings, combined with those of studies that link stage on presentation to poor outcomes, have led to our conclusion that TCV is an aggressive malignancy warranting appropriate treatment and close follow-up.

Adult↗
PubMed1999

What is the real clinical utility of echocardiography? A prospective observational study.

This was a prospective, structured interview to evaluate physician expectations of echocardiography and the subsequent impact on patient care. The setting involved requests for echocardiograms in patients admitted to a tertiary care teaching hospital. Measurements included assessment of the diagnostic and therapeutic implications of echocardiography perceived by the physicians and subsequently reported and confirmed by blinded chart review. From January to May 1997, 542 echocardiograms were performed on 500 inpatients (age 62 +/- 17 years; 56% men). Referring physicians were mainly house staff (83%) and from medical services. The main indications were evaluation of left ventricular function (54%) or valve function (16%). At the time of the request, 89% of physicians believed that echocardiography was needed to guide future investigations or treatment, although in 24% of cases, physicians could not provide details of such. A reported change in treatment occurred in 57% and was validated by chart review in 38%. Changes occurred more frequently in patients in the intensive care unit versus those not in the intensive care unit (54% vs 37%, P =.02) but were similar between attending physicians and house staff (frequency of change 41% vs 39%, P = not significant) and between those with and those without previous echocardiograms (38% vs 39%, P = not significant). The utility of the echocardiogram to influence treatment decisions in hospitalized patients is high, especially in critically ill patients. However, this impact is less than is anticipated at the time of the initial request. Further studies involving more select populations of patients are required.

Clinical Competence↗
PubMed1997

Restoring a fair workers' compensation system for employer and employee.

The costs of workers' compensation have curtailed in recent years, perhaps in part as a result of MCO's efforts in this area. Managed care organizations that consider jumping into the workers' compensation arena often make basic errors in developing their programs and networks. The author reminds MCOs of the practical points they need to consider.

Accidents, Occupational↗
PubMed1996

Distribution of nerve fibers in the standard incision for carpal tunnel decompression.

Twenty-two paired biopsy specimens of skin and subcutaneous tissue from the proximal and distal halves of the conventional curvilinear incision or carpal tunnel decompression were histologically examined. The specimens were immunohistochemically stained with S100 antibody to highlight the nerve fibers. The mean count of free nerve endings in the proximal biopsy site was 4.42/mm2 (SD, 2.97; range, 1.23-12.27), compared to 4.2/mm2 (SD, 2.71; range, 1.01-10.50) in the distal biopsy specimens. This difference was not statistically significant (p = .20, Wilcoxon's signed ranks [matched pairs] test). The proximal incision site for carpal tunnel decompression did not appear to be more neuroreceptive than the distal incision site, providing no support for the implication of proximal incision sites in proximal scar tenderness.

Carpal Tunnel Syndrome↗
PubMed1994

Induction of a dose-related increase in sulfobromophthalein uptake velocity in freshly isolated rat hepatocytes by phenobarbital.

To determine whether phenobarbital affects hepatocellular bilirubin/sulfobromophthalein uptake mechanism, we administered it to male Sprague-Dawley rats, body weight 175 +/- 25 gm, at doses of 1 to 75 mg/kg body wt/day for 7 days. Control rats were given an equivalent volume of physiological saline solution. On day 8, hepatocytes were isolated by means of collagenase perfusion, suspended in Hanks' solution without albumin and incubated with high specific activity (3 Ci/mmol) [35S]sulfobromophthalein, which was synthesized in our laboratory and purified by means of a new reverse-phase high-pressure liquid chromatography procedure. The initial uptake rate of sulfobromophthalein was determined at sulfobromophthalein concentrations of 1 to 50 mumol/L with a rapid filtration technique. The maximum uptake velocity and Michaelis constant for sulfobromophthalein uptake at each phenobarbital dose were determined by means of a computer analysis. In control studies, maximum uptake and Michaelis constant were 48.0 +/- 16.7 (mean +/- S.D.) pmol/50,000 cells/min and 22 +/- 4 mumol/L, respectively. Maximum uptake velocity increased linearly with the log of the phenobarbital dose (r = 0.98, p < 0.01), the increase achieving statistical significance at a dose of 3 mg/kg/day. Michaelis constant, however, was essentially unchanged at phenobarbital doses of 50 mg/kg/day or less. The maximal observed increase in maximum uptake velocity of sulfobromophthalein (to 619% of control values) was appreciably greater than the maximal increase in UDP-glucuronyltransferase activity (200% of control) or immunoreactive ligandin concentrations (260% of control) seen in earlier studies, suggesting a direct effect on the plasma membrane transport mechanism.

Animals↗
PubMed1993

Initiation of atrial fibrillation in the Wolff-Parkinson-White syndrome: the importance of the accessory pathway.

Atrial fibrillation in the Wolff-Parkinson-White syndrome may be related to microreentry in the accessory pathway. If such is the case, catheter ablation of the accessory pathway should eliminate atrial fibrillation. Among 95 patients undergoing catheter ablation, 20 had atrial fibrillation during standard electrophysiologic study (atrial vulnerability) before ablation. There were 16 women and four men with a mean age of 32 years. Before ablation six patients required electrical cardioversion. Thirty minutes after ablation, 11 continued to have inducible atrial fibrillation. Atrial fibrillation terminated spontaneously in every patient after ablation. A control group of 20 patients with accessory pathway ablation had no inducible atrial fibrillation before or after ablation. Catheter ablation had no effect on atrial properties including functional refractory period (227 +/- 37 vs 215 +/- 29 msec before versus after ablation, mean +/- SD) or wavelength (7.4 +/- 3.2 vs 7.2 +/- 2.7 before versus after ablation). These data suggest that an intact accessory pathway is not necessary for initiation of atrial fibrillation in most patients with Wolff-Parkinson-White syndrome. A rapid ventricular response over the accessory pathway may facilitate the perpetuation of atrial fibrillation in persons prone to this arrhythmia.

Adult↗
PubMed1993

Comparative atrioventricular node properties after radiofrequency ablation and operative therapy of atrioventricular node reentry.

The anatomical substrate for atrioventricular (AV) node reentry is unclear. To gain insights into the mechanism of cure of AV node reentry by nonpharmacological techniques, we compared AV node properties in 53 patients undergoing operative therapy (perinodal dissection) and 43 undergoing radiofrequency ablation (28 posterior approach, 15 anterior approach). Anterior radiofrequency ablation was associated with significant AH prolongation (62 +/- 18 msec vs 136 +/- 64 msec, P < 0.0001), loss of "fast" pathway physiology, and no change in the anterograde refractory period of the AV node (273 +/- 24 msec vs 268 +/- 28 msec, P = NS). Posterior radiofrequency ablation did not change the AH interval (67 +/- 17 msec vs 68 +/- 17 msec, P = NS), prolonged AV node effective refractory period (275 +/- 48 msec vs 320 +/- 55 msec, P < 0.0001), and was associated with loss of "slow pathway" physiology. Operative treatment prolonged the AH interval (66 +/- 18 msec vs 83 +/- 37 msec, P < 0.0001) and the AV node effective refractory period (264 +/- 52 msec vs 364 +/- 112 msec, P < 0.0001), and affected dual pathway physiology inconsistently. These data support the view that the "fast" and "slow" pathways are distinct perinodal entities that can be selectively ablated. The operative approach causes more diffuse and variable injury to the AV node region.

Adolescent↗
PubMed1992

An anatomically guided approach to atrioventricular node slow pathway ablation.

Radiofrequency ablation of the "slow" pathway of the atrioventricular (AV) node reentrant circuit may be guided by electrophysiologic ("slow pathway potential") or anatomic landmarks. Experience with a systematic, anatomically guided approach in 25 patients (20 women and 5 men, aged 38 +/- 15 years) with typical AV node reentry is described. The slow pathway is assumed to be the posterior input to the AV node, approaching the nodal region in the corridor between the tricuspid annulus and the orifice of the coronary sinus. A series of radiofrequency lesions are given to interrupt this corridor at its entrance to Koch's triangle. If this is unsuccessful, the series of lesions are repeated progressively at higher levels approaching the AV node. The major end point for success is elimination of the slow pathway as determined by extrastimulus testing. A mean of 1.2 +/- 0.2 ablative sessions (20 +/- 12 applications of energy) achieved clinical success in 24 of 25 patients (96%) at a follow-up of 8.6 +/- 2.2 months. Anterograde Wenckebach cycle length increased from 361 +/- 67 ms to 398 +/- 70 ms (p = 0.01), yet the atrio-Hisian interval in sinus rhythm did not change (69 +/- 17 ms before vs 65 +/- 15 ms after ablation), p = 0.22. Retrograde Wenckebach cycle length was not affected (348 +/- 78 ms before vs 366 +/- 82 ms after ablation). During ablation, transient third-degree AV block occurred in 6 patients with no permanent sequelae. This approach provides a systematic, expedient technique to eliminate slow pathway conduction based on anatomic landmarks.

Adult↗