Biomedical subjects

Edward Chin

Publications and source records attributed to Edward Chin.

10 recordsLinked to original sources

PubMed2006

A liver specific gene that is expressed in growth hormone transgenic mice and in normal female mice as a function of age.

Growth hormone (GH) acts on various organs to exert its growth and metabolic effects. GH induces transcription of a number of genes in different organs including liver. By performing subtractive hybridization analysis on liver cDNAs of GH transgenic and non-transgenic mice, differentially expressed cDNAs were obtained. This paper describes the isolation and characterization of a liver cDNA, termed cDNA #5, that contains 1897 bp and is predicted to encode a protein (P5) of 512 aa residues. P5 has five immunoglobulin related domains thus allowing it to be classified as a member of the immunoglobulin super family (IGSF). Also, P5 shows significant similarity to both rat and human alpha-1-B glycoprotein which is an acidic serum protein of unknown function. mRNA #5 was detected in the liver hepatocytes of male and female GH transgenic mice and in the liver of female, but not of male, non-transgenic mice. mRNA #5 was not present in dwarf mice including the Ames dwarf, those that express a GH antagonist and those with the GH receptor and binding protein gene disrupted. These findings suggest that induction of mRNA #5 in the liver requires a continuous pattern of GH secretion and an intact GH-GH receptor-signaling complex. mRNA #5 levels in female non-transgenic mice were observed to vary with age implying that gender-specific age-dependent factor(s) may be involved in the induction of mRNA #5. The appearance of mRNA #5 in post-hepatectomized liver that coincides with the proliferative phase of liver regeneration suggests that it may be involved in hepatocyte proliferation. Together these data suggest that expression of cDNA #5 is liver-specific, sexually dimorphic, age-dependent, and may be involved in hepatocyte hyperplasia and liver enlargement.

Age Factors↗

PubMed2006

Minimally invasive thyroidectomy: basic and advanced techniques.

OBJECTIVE: Minimal access surgery in the thyroid compartment has evolved considerably over the past 10 years and now takes many forms. We advocate at least two distinct approaches, depending on the disease process and multiple patient factors. The technical aspects are explored in depth with liberal use of videographic demonstration. METHODS: The authors conducted a comparison of two distinct surgical techniques with photographic and videographic documentation of two distinct minimal access approaches to the thyroid compartment termed minimally invasive thyroidectomy (MITh) and minimally invasive video-assisted thyroidectomy (MIVAT). Both historic and previously unpublished data (age, gender, pathology, incision length, and complications) are systematically analyzed. RESULTS: Patients who underwent minimally invasive thyroidectomy (n = 31) had a mean age of 39.4 +/- 10.7 years; seven were male and 24 were female. The most common diagnosis was follicular or Hürthle cell adenoma (29%), followed by papillary or follicular cancer (26%). The mean incision length was 4.9 +/- 1.0 cm. One patient developed a hypertrophic scar and one patient developed thrombophlebitis of the anterior jugular vein. There were 14 patients in the MIVAT group with a mean age of 43.7 +/- 11.4 years; one was male and 13 were female. The majority of patients had follicular adenoma (42.9%) or papillary carcinoma (21.4%) as their primary diagnosis. The mean incision length was 25 +/- 4.3 mm (range, 20-30 mm), and there were no complications. CONCLUSIONS: Two distinct approaches to minimal access thyroid surgery are now available. The choice of approach depends on a number of patient and disease factors. Careful patient selection will result in continued safe and satisfactory performance of minimally invasive thyroid surgery.

Adenoma, Oxyphilic↗

PubMed2006

Thyroid surgery: changing patterns of practice.

OBJECTIVE: The practice of thyroidectomy has evolved over the past 10 years with the introduction of minimally invasive surgery, laryngeal nerve monitoring, and outpatient surgery. We sought to investigate corresponding trends in the disciplines performing thyroid surgery. METHODS AND MATERIALS: The authors conducted a nonrandomized, case-controlled comparison of surgical volumes and systematic analysis of publication volumes. Two surrogates for the proportion of thyroidectomies being performed by otolaryngologists-head and neck surgeons (OHNS) and general surgeons (GS) were chosen: 1) the operative case logs of graduates from American training programs in OHNS and GS from 1995 through 2004 were compared; and 2) the number of scientific articles published relating to thyroid surgery were systematically queried for two timeframes (1990-1994 and 2000-2004). RESULTS: There was a gradual increase in the mean number of thyroidectomies performed by GS residents from 13.2 in 1995 to 18.2 in 2004. During the same timeframe, the mean number of thyroidectomies performed by OHNS residents more than doubled from 15.0 to 33.5. The number of American GS thyroid publications from 1990 to 1994 was 79, compared with 98 in the period 2000 to 2004, representing a 24% increase. During the same timeframe, the number of American OHNS articles increased from 14 to 49 (a 250% increase). The relative proportion of thyroid publications authored by American otolaryngologists more than doubled from 15.1% to 33.3% (P = .0017). CONCLUSIONS: A clear trend is emerging in the pattern of thyroid surgery in that a growing proportion of publications are being authored by otolaryngologists compared with general surgeons, and the average number of procedures performed by graduating chief residents is now 84% higher in otolaryngology compared with general surgery.

Case-Control Studies↗

PubMed2006

Ultrasonic technology facilitates minimal access thyroid surgery.

OBJECTIVES: Options for controlling the vasculature during thyroid surgery include suture ligatures, vessel clips, and bipolar cautery. Ultrasonic technology represents an alternative to conventional techniques in which the vessels are simultaneously sealed and divided. We sought to determine the safety and efficacy of thyroidectomy with ultrasonic technology. DESIGN: Nonrandomized, prospective analysis of a series of patients undergoing thyroidectomy at the Medical College of Georgia. METHODS AND MATERIALS: The records of 51 consecutive patients who underwent thyroid surgery between December 2004 and June 2005 were reviewed. Patients in whom ultrasonic technology (Harmonic-ACE, Ethicon Endo-Surgery, Cincinnati, OH) was used comprised the study population. RESULTS: Forty-four of 51 patients underwent thyroidectomy with the assistance of ultrasonic technology. There were 4 males and 40 females with a mean age of 43.5 +/- 15.8 years. Twenty-two patients had a total thyroidectomy, 18 underwent unilateral lobectomy, and 4 underwent completion thyroidectomy. The overall mean incision length was 5.0 +/- 2.6 (range 2-12) cm. A subgroup of patients underwent minimally invasive video-assisted thyroidectomy (n = 13) and had a mean incision length of 29.3 +/- 0.8 mm. There were no cases of permanent injury to the recurrent laryngeal nerve and no cases of persistent hypoparathyroidism. Blood loss ranged from 5 mL to 100 mL, with a mean of 26.7 +/- 21.8 mL. CONCLUSIONS: Ultrasonic technology facilitates thyroid surgery, particularly when a minimally invasive approach is undertaken. It reliably seals and divides the thyroid vasculature and will likely replace other methods of managing the thyroid blood supply.

Adult↗

PubMed2006

Clinical implementation of endoscopic thyroidectomy in selected patients.

OBJECTIVES: Systematic investigation of minimal access thyroid compartment surgery combined with the advent of several key new technologies has culminated in the implementation of endoscopic thyroidectomy in specific clinical situations. STUDY DESIGN: : The authors conducted a prospective, nonrandomized analysis of a consecutive cohort of surgical patients from the Medical College of Georgia Thyroid Center. METHODS AND MATERIALS: A series of patients meeting specific criteria underwent thyroid surgery with the intention of performing endoscopic thyroidectomy. Demographic and clinical data were prospectively collected and included age, gender, indications for surgery, length of incision, need for conversion, and pathology. RESULTS: Thirty-five patients successfully underwent 36 endoscopic thyroidectomies between February 2005 and March 2006 (representing 28.8% of the 125 thyroidectomies done during that period of time). There were 32 females and three males with a mean age of 45.3 +/- 13.9 years. There were five total thyroidectomies and 31 hemithyroidectomies. The mean incision length was 24.2 +/- 0.5 mm. There were no cases of permanent hypocalcemia or recurrent laryngeal nerve paralysis. Factors that increased the difficulty of endoscopic surgery included obesity, the presence of thyroiditis, and nodules >2.5 cm. CONCLUSIONS: The combination of new technology and careful experimental investigation has spawned a new era of thyroidectomy in which definitive management of thyroid pathology may be accomplished through an incision of <1 inch. This approach is feasible in the hands of surgeons with high-volume thyroidectomy practices who are comfortable with endoscopic principles. The cosmetic advantages are self-evident.

Adenoma↗

PubMed2005

Minimally invasive thyroidectomy using the Sofferman technique.

OBJECTIVES: Access to the thyroid compartment has traditionally been achieved by a Kocher incision followed by subplatysmal flap elevation and strap muscle retraction. A combination of novel access techniques was used to allow for minimally invasive thyroidectomy (MITh). METHODS AND MATERIALS: A prospective, nonrandomized evaluation of consecutive patients undergoing thyroidectomy was performed. A minimally invasive incision (< or =6 cm) was used in conjunction with the Sofferman technique (transection of the strap muscles) and videoendoscopic assistance to perform hemithyroidectomy or total thyroidectomy in eligible patients. Prospectively collected data include age, sex, pathology, incision length, duration of surgery, and blood loss and complications were considered. RESULTS: Forty-four patients underwent 48 thyroid surgeries between September 2003 and May 2004. There were 13 men and 31 women, with a mean age of 41.9 (range 19-73) years. Thirty-one (64.6%) of these were eligible to be performed by MITh; the remainder (n = 17, 35.4%) underwent conventional thyroidectomy. The mean incision length in the MITh cohort was 4.9 +/- 1.0 cm compared with 9.1 +/- 1.5 cm for conventional thyroidectomy. The mean surgical time for minimally invasive hemithyroidectomy was 115.7 minutes (n = 23), and for total thyroidectomy was 147.4 minutes (n = 8). There were no cases of permanent hypocalcemia or recurrent laryngeal nerve paralysis in either group. No patients in the MITh group had to be converted to a conventional thyroidectomy. The cosmetic results were excellent, although one patient in the MITh group developed a mildly hypertrophic scar that responded to triamcinolone injection. CONCLUSIONS: MITh is safe in carefully selected patients and probably results in more rapid wound healing. The cosmetic result is superior to that achieved with conventional thyroidectomy.

Adult↗

PubMed2005

Gynecomastia and hypertension.

Palpable dense and mobile subareolar tissue in the male breast defines the presence of gynecomastia. For the hypertension specialist, breast enlargement in men provides a clue to a secondary cause of hypertension or an adverse antihypertensive drug reaction. Hyperthyroidism, chronic renal failure, adrenal hyperplasia or tumors, amphetamine, cyclosporine, and anabolic steroids are secondary causes of hypertension associated with gynecomastia. Reserpine, methyldopa, and spironolactone are older drugs associated with gynecomastia; however, calcium antagonists (more commonly), angiotensin-converting enzyme inhibitors, and alpha1 blockers may also be associated with this finding. Treatment is directed to removal of the underlying cause.

Antihypertensive Agents↗

PubMed2004

Proteolytic processing of TGFalpha redirects its mitogenic activity: the membrane-anchored form is autocrine, the secreted form is paracrine.

Wild-type transforming growth factor alpha (TGFalpha) expression in lactotrope cells in the pituitary gland led to lactotrope-specific pituitary hyperplasia and adenomata. To indicate whether the EGF receptor is involved in this TGFalpha-mediated phenotype, we bred TGFalpha mice with mice expressing the cytoplasmic truncated-EGF receptor (EGFR-tr), which is dominant-negative in other models. These bitransgenic mice developed pituitary pathology despite expression of the dominant-negative receptor. To further characterize this observation, we generated two lineages of transgenic mice that overexpress mutant forms of TGFalpha: a processed soluble form (s TGFalpha) and a cytoplasmic-deleted form (TGFalphaDeltaC). While sTGFalpha expression in lactotrope cells failed to induce autocrine lactotrope hyperplasia, the pituitary became very enlarged due to proliferation of neighboring interstitial cells. In contrast, the TGFalphaDeltaC mice did not develop a phenotype, although the mRNA and protein were present in the pituitary and this form of TGFalpha was confirmed to be biologically active and targeted properly to the plasma membrane of cultured CHO cells. The results suggest that the cytoplasmic domain of TGFalpha is required for autocrine parenchymal tumor formation in the pituitary gland. This signal cannot be inhibited by the EGFR-tr. Conversely, the released form of TGFalpha appears to have primarily paracrine activity.

Animals↗

PubMed2002

Streptozotocin, an O-GlcNAcase inhibitor, blunts insulin and growth hormone secretion.

Type 2 diabetes mellitus results from a complex interaction between nutritional excess and multiple genes. Whereas pancreatic beta-cells normally respond to glucose challenge by rapid insulin release (first phase insulin secretion), there is a loss of this acute response in virtually all of the type 2 diabetes patients with significant fasting hyperglycemia. Our previous studies demonstrated that irreversible intracellular accumulation of a glucose metabolite, protein O-linked N-acetylglucosamine modification (O-GlcNAc), is associated with pancreatic beta-cell apoptosis. In the present study, we show that streptozotocin (STZ), a non-competitive chemical blocker of O-GlcNAcase, induces an insulin secretory defect in isolated rat islet cells. In contrast, transgenic mice with down-regulated glucose to glucosamine metabolism in beta-cells exhibited an enhanced insulin secretion capacity. Interestingly, the STZ blockade of O-GlcNAcase activity is also associated with a growth hormone secretory defect and impairment of intracellular secretory vesicle trafficking. These results provide evidence for the roles of O-GlcNAc in the insulin secretion and possible involvement of O-GlcNAc in general glucose-regulated hormone secretion pathways.

Acetylglucosamine↗

PubMedDate not supplied

Contemporary management of thyroid cancer.

Thyroid cancer is a relatively common and frequently curable malignant neoplasm, accounting for nearly 2% of all new cancers diagnosed annually in the United States. The diagnostic and management options have evolved considerably in the past decade, and a current understanding of these trends in the standard of care have assumed an important consideration in the practices of head and neck surgeons and endocrinologists alike. We sought to review the epidemiology and pathology of the several types of thyroid cancer and to present our evidence-based management algorithm. Every effort was made to offer alternative treatment strategies and supporting data where available. In addition to reviewing well-established approaches to diagnosis and management, emphasis is placed on newer techniques, including minimally invasive thyroidectomy, molecular detection of disease propensity, and the use of recombinant thyrotropin prior to radioiodine ablation.

Adenocarcinoma, Follicular↗