Search PubMed⌕ Search

Biomedical subjects

Orlo H Clark

Publications and source records attributed to Orlo H Clark.

81 records · Page 5Linked to original sources
PubMed2002

Results of laparoscopic adrenalectomy for suspected and unsuspected malignant adrenal neoplasms.

BACKGROUND: Laparoscopic resection for malignant adrenal tumors is controversial, because they are rare and limited data exist in the literature. HYPOTHESIS: Laparoscopic adrenalectomy for malignant adrenal tumors is safe and effective. PATIENTS AND METHODS: Twenty-three patients who had a laparoscopic approach for suspected and unsuspected malignant adrenal tumors were studied retrospectively. The adrenal mass was suspected to be metastatic if the patient had a history of previous extra-adrenal primary malignancy and/or positive fine-needle aspiration cytologic findings. A primary adrenal cancer was suspected if there were positive fine-needle aspiration cytologic findings and/or a malignant adrenal imaging phenotype. MAIN OUTCOME MEASURES: (1) Margins of tumor resection, (2) tumor recurrence (locoregional, port site, and distant), and (3) disease-free survival. RESULTS: Twenty-three patients (15 men and 8 women) had 24 laparoscopic procedures (20 adrenalectomies, 3 biopsies, and 1 diagnostic laparoscopy). Permanent histologic specimens in the 23 patients showed 5 adrenocortical cancers, 1 undifferentiated adrenal cancer, 13 adrenal metastases, 2 lymphomas, and 2 cases with no evidence of tumor. Clinically suspected adrenal metastases were true positive in 19 patients (83%). The sensitivity of fine-needle aspiration cytology was 57% (n = 7). Only 1 of 6 patients with primary adrenal cancer was suspected to have a malignant tumor preoperatively. The tumor resection margin was negative in all adrenalectomies. There were 3 locoregional recurrences (2 local and 1 lymph node metastasis) in the 6 patients with primary adrenal cancer, no port site recurrences, and 4 distant recurrences in 13 patients with metastatic adrenal tumors. The disease-free survival was 65% at a mean follow-up time of 3.3 years (range, 1-7 years). CONCLUSIONS: A laparoscopic approach in patients with suspected adrenal metastasis can be both diagnostic and therapeutic, and achieves complete tumor resection. In contrast, laparoscopic adrenalectomy for clinically unsuspected adrenocortical cancer is associated with a high recurrence rate. Furthermore, preoperative fine-needle aspiration cytology for the evaluation of suspected malignant adrenal tumors is unreliable.

Adrenal Gland Neoplasms↗
PubMed2002

Multiple endocrine neoplasia type I.

Multiple endocrine neoplasia type I is a rare autosomal dominant disorder with many endocrine and nonendocrine manifestations. Hyperparathyroidism, islet cell tumors, and pituitary tumors are diagnosed most commonly in these patients. There is controversy regarding treatment of the different manifestations and screening modalities of this disorder because no large series has determined the best therapeutic approach. Our institution advocates early screening with biochemical and radiographic testing in patients with a definite predilection for this disorder. Patients with hyperparathyroidism should undergo early surgical intervention of at least three and a half glands combined with bilateral upper thymectomy through a cervical incision. Although the recurrence rate is high, disease-free survival can be for as long as 30 years. Pituitary tumors are predominantly prolactinomas and growth hormone-releasing tumors. Prolactinomas usually require pharmacologic therapy, whereas growth hormone-releasing tumors are treated surgically. Enteropancreatic tumors should be treated surgically or medically, depending on the hormone secreted. Insulinomas respond well to distal pancreatectomy, with enucleation of the tumor from the head and uncinate process of the pancreas. However, there is controversy regarding the surgical treatment of gastrinomas. Carcinoid tumors should be treated with early surgical intervention. Adrenal lesions are thought to occur in association with pancreatic lesions and commonly have an indolent course. Adrenocortical cancers are uncommon in patients with multiple endocrine neoplasia type I. Skin lesions can be excised when cosmetically unappealing.

Adult↗
PubMed2002

Accuracy of selective venous sampling for intact parathyroid hormone in difficult patients with recurrent or persistent hyperparathyroidism.

BACKGROUND: Preoperative noninvasive localization studies of the neck and mediastinum are beneficial before reoperation. However, the role of selective venous sampling (SVS) for parathyroid hormone (PTH) in reoperative parathyroid surgery has never been clearly defined. The purpose of this study was to evaluate the accuracy of SVS when applied selectively to the subset of patients with indeterminate noninvasive localization studies. METHODS: Between January 1990 and December 2001, 64 of 235 (27%) patients with persistent or recurrent hyperparathyroidism were considered candidates for SVS in addition to noninvasive localization studies. Accuracy of SVS for PTH was retrospectively evaluated. RESULTS: Successful surgical treatment was achieved in 86% of these patients. SVS for PTH yielded true-positive results in 75% of patients and was not useful for the surgeon in 17% (completely false-positive in 12% and indeterminate in 5%). In 2% of patients, SVS identified successfully 1 gland but failed to locate another abnormal gland. In 6% of patients, the location of the abnormal parathyroid tissue remained unknown, and the patients have persistent hyperparathyroidism. CONCLUSIONS: We showed that SVS is clinically useful in patients with persistent or recurrent hyperparathyroidism when the noninvasive localization studies do not clearly localize the abnormal parathyroid glands.

Adolescent↗
PubMed2002

Computer-assisted evoked electromyography with stimulating surgical instruments for recurrent/external laryngeal nerve identification and preservation in thyroid and parathyroid operation.

BACKGROUND: The reported incidence of recurrent laryngeal nerve (RLN) palsy/paralysis in thyroid and parathyroid operation ranges from 2% to 13%. Injury to the external branch of the superior laryngeal nerve (EBSLN) is less clearly documented. We hypothesized that a novel evoked electromyography system using an audio warning alarm might be beneficial for detection and preservation of the RLN and EBSLN. METHODS: A total of 117 thyroid/parathyroid operations were performed using a nerve locator/monitor (Neurovision SE, RLN Systems Inc, Jefferson City, Mo). Dissection was performed using a stimulating hemostat with conduction to an endotracheal surface electrode. RESULTS: A total of 97 thyroidectomies (50 total, 47 lobectomies) and 20 parathyroidectomies (16 directed, 4 bilateral) were performed representing 176 RLN and 152 EBSLN at risk. Of 176 RLN, 161 were correctly identified by the nerve stimulator alarm including 2 nonrecurrent nerves. The cricothyroid space and the superior pole vessels were scanned to identify the EBSLN by observing for cricothyroideus contraction or an alarm. Fourteen of 152 (8.9%) cases of type 2 anatomy were suggested where meticulous dissection of superior pole vessels prevented EBSLN injury. CONCLUSIONS: Computer-assisted evoked electromyography with stimulating surgical instruments is a useful surgical tool. This technology may be especially useful in reoperation in dense scar tissue and preserving the EBSLN in thyroid operation.

Diagnosis, Computer-Assisted↗
PubMed2002

Apoptosis regulating genes, bcl-2 and bax, and human telomerase reverse transcriptase messenger RNA expression in adrenal tumors: possible diagnostic and prognostic importance.

BACKGROUND: Apoptosis-suppressing gene, bcl-2, and apoptosis-inducing gene, bax, are expressed in various tumors. Human telomerase reverse transcriptase (hTERT) expression is increased in many cancers. The purpose of this investigation was to determine whether bcl-2 or bax gene expression differs between benign and malignant adrenal tumors, and whether hTERT gene expression correlates with the prognosis of patients with adrenal cancer. METHODS: Expression of bcl-2 and bax from 52 adrenal surgical specimens was analyzed by reverse transcription-polymerase chain reaction. Expression of hTERT was analyzed by real-time quantitative reverse transcription-polymerase chain reaction, and expressed using the delta-delta threshold cycle method. RESULTS: All normal adrenal tissues (n = 7) and benign adrenal tumors (n = 41) expressed bcl-2 and bax, whereas all adrenocortical cancers (n = 4) expressed bcl-2 but not bax. Expression of hTERT was increased in adrenocortical cancers compared with that in normal tissues (P <.05), cortical adenomas (n = 17) (P <.05), cortical hyperplasias (n = 4) (P <.05), and pheochromocytomas (n = 20) (P <.05). The one patient with an adrenocortical cancer without increased hTERT expression is alive with distant metastasis 5 years after adrenalectomy. The other 3 patients with adrenocortical cancer died 5 to 24 months after adrenalectomy. CONCLUSIONS: Expression of bax gene appears to distinguish adrenal cancer from benign adrenal tumors. Gene expression of hTERT should be investigated as a prognostic marker in adrenal cortical cancers.

Adenoma↗
PubMed2002

Increasing the effectiveness of radioactive iodine therapy in the treatment of thyroid cancer using Trichostatin A, a histone deacetylase inhibitor.

BACKGROUND: Radioactive iodine is used to identify and treat recurrent and metastatic thyroid cancer of follicular cell origin. Between 30% and 40% of thyroid cancers are either resistant or become resistant to radioactive iodine. Increased sodium-iodide symporter (NIS) and decreased Pendrin (PDS) activity may be associated with increased radioactive iodine effectiveness. In this investigation the effects of Trichostatin A (TSA), a histone deacetylating inhibitor, on human thyroid NIS and PDS gene expression was investigated. METHOD: Cell lines from papillary, Hürthle, and follicular cell carcinomas were treated with TSA for 72 hours at concentrations up to 100 ng/mL. NIS and PDS gene expression was determined using quantitative RT-polymerase chain reaction. RESULTS: . NIS messenger RNA expression in cell carcinomas was increased 107- (1.8-307) and 217- (5.7-408) fold in papillary, 39- (20-63) and 58- (37-80) fold in Hürthle, and 459- (178-810) and 781- (412-1229) fold in follicular after treatment with 50 and 100 ng/mL of TSA, respectively. PDS messenger RNA expression in cell carcinomas was decreased 0.22- (0.05-0.45) and 0.27- (0.09-0.47) fold in papillary, 0.53- (0.46-0.60) and 0.54- (0.44-0.64) fold in Hürthle, and 0.32- (0.26-0.39) and 0.56- (0.47-0.64) fold in follicular, after the same treatment. CONCLUSIONS: In thyroid cancer cell lines, TSA dramatically increased NIS gene expression and reduced PDS expression. The increased NIS expression and reduced PDS expression may make radioiodine therapy more effective in patients with thyroid cancer, especially when the tumors have no or low uptake of radioiodine.

Carcinoma, Papillary↗
PubMed2002

Chromosomal aberrations by comparative genomic hybridization in hürthle cell thyroid carcinomas are associated with tumor recurrence.

Hürthle cell thyroid neoplasms are classified as variants of follicular neoplasms, but they have distinct clinicopathological features. Chromosomal aberrations by comparative genomic hybridization (CGH) are common in Hürthle cell neoplasms. However, there is currently only limited information concerning the relationship between the chromosomal aberrations by CGH and tumor behavior. We, therefore, investigated chromosomal aberrations in primary Hürthle cell neoplasms (13 carcinomas and 15 adenomas) using CGH and correlated the aberrations identified with tumor node metastasis (TNM) stage, tumor differentiation, capsular invasion, and tumor recurrence. Chromosomal aberrations were found in 62% (8 of 13) of carcinomas and 60% (9 of 15) of adenomas. Overall, common chromosomal gains were found on 5p (29%), 5q (36%), 7 (29%), 12p (14%), 12q (21%), 17p (29%), 17q (32%), 19p (32%), 19q (25%), 20p (21%), 20q (29%), and 22q (18%). Common chromosomal losses were found on 2q (18%) and 9q (18%). Thirty-eight percent (5 of 13) of carcinomas were TNM stage III, 31% (4 of 13) were moderately to poorly differentiated, and 46% (6 of 13) were intermediately to widely invasive. Recurrence occurred in 38% (5 of 13). Carcinomas that subsequently recurred had a greater number of chromosomal gains (9.0 vs. 1.3; <0.005) and had more frequent chromosomal gains on 12q, 19q, and 20p (<0.001), 5p, 7, 19p, and 20q (<0.005), and 12p (<0.01) than those that did not recur. Five of the eight (63%) patients with aberrations developed recurrence, whereas none of the five patients without aberrations developed recurrence. In conclusion, chromosomal gains by CGH on 5p, 7, 12p, 12q, 19p, 19q, 20p, and 20q in Hürthle cell carcinomas are associated with tumor recurrence. Such chromosomal aberrations may be predictive for recurrent disease in patients with Hürthle cell thyroid carcinoma.

Adenoma↗
PubMed2002

Parathyroid surgery: separating promise from reality.

We set out to determine the accuracy in predicting the success of biochemical and localizing studies for use in a minimally invasive parathyroidectomy. Preoperative sestamibi scans, intraoperative gamma-probe examinations, and intraoperative PTH (IOPTH) monitoring were performed on a prospective cohort of patients. Seventy-one patients were included in the study. Of the 59 patients (83%) with primary HPT, adenoma localization by sestamibi scanning was correct in 95% with solitary adenomas, but was correct in only 25% of the 14 patients with multiple adenomas. In patients with secondary and tertiary disease, sestamibi scanning incorrectly identified a single hot spot in 64% of cases. In no case of hyperplasia was the probe useful in locating other glands after a single gland was removed. IOPTH was accurate in 78% of patients with primary disease and in only 45% of patients with nonprimary disease. A minimal approach can be considered in a select group of patients that does not have familial primary HPT, secondary or tertiary disease, coexisting thyroid pathology, or an equivocal sestamibi scan. Only patients with a positive single hot spot on sestamibi scan can be considered candidates. Using this criteria only 64% of all patients with hyperparathyroidism are candidates for a minimally invasive approach. The combination of a solitary hot spot on sestamibi scan and a fall in IOPTH allows the surgeon to make the correct decision regarding the need to convert to a bilateral approach in 93% of these selected patients.

Adult↗