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Biomedical subjects

H C Lam

Publications and source records attributed to H C Lam.

At least 19 recordsLinked to original sources
PubMed2001

Internal carotid artery hemorrhage after irradiation and osteoradionecrosis of the skull base.

OBJECTIVE: To evaluate the clinical presentation and management of internal carotid artery rupture after irradiation and osteoradionecrosis of the skull base. STUDY DESIGN AND SETTING: A retrospective review of the patients in an otorhinolaryngology-head and neck secondary and tertiary referral center. METHODOLOGY: From January 1993 to December 1996, patients with hemorrhage from internal carotid artery as a complication of irradiation and osteoradionecrosis of skull base were reviewed and analyzed. RESULTS: Four patients with internal carotid arterial rupture were included in this study. Angiography was performed in all cases. Embolization of the aneurysm was performed on 2 patients and the remaining 2 patients underwent occlusion of their internal carotid arteries. Three of the 4 patients did not survive. The fourth is currently alive and well 18 months after embolization of 1 internal carotid artery. CONCLUSION: Skull base osteoradionecrosis with bleeding from internal carotid artery is a potentially fatal complication of irradiation. Angiography was the mainstay of diagnosis with embolization of the aneurysm and embolization or ligation of the internal carotid artery being the management options. Internal carotid artery occlusion is the definitive treatment provided cross circulation is adequate. SIGNIFICANCE: The advantages and disadvantages of the treatment options are discussed and a management protocol is proposed.

Aged↗
PubMed2001

Excision of the preauricular sinus: a comparison of two surgical techniques.

OBJECTIVES: To compare the long-term recurrence rate of the standard technique (simple sinectomy) and the supra-auricular approach (wide local excision) for the surgical management of preauricular sinuses. STUDY DESIGN: Retrospective cohort. METHODS: Fifty-four patients with a preauricular sinus excised between May 1986 and December 1996 were included in this study. All patients were categorized into one of two groups based on the type of surgery performed: the standard technique or the supra-auricular approach. The medical records were then reviewed and the latest information concerning the recurrence of a preauricular sinus were updated by phone interview. The recurrence rate of these two groups was statistically analyzed by the Fisher exact test. RESULTS: Forty-nine of 54 patients were successfully contacted with data updated and analyzed. The 32% recurrence rate of the standard excision (n = 25) was significantly higher than the 3.7% recurrence rate of the supraauricular approach (n = 27; two-tailed test, P = .01). CONCLUSION: The supra-auricular approach for excision of a preauricular sinus has a statistically lower recurrence rate in comparison to the standard technique.

Abscess↗
PubMed2001

Management of ingested foreign bodies: a retrospective review of 5240 patients.

This review was carried out to assess the effectiveness of our protocol designed for the management of ingested foreign bodies. It was a retrospective review of 5240 patients with ingested foreign bodies admitted over a five-year period to the Ear Nose and Throat Unit. These patients were managed according to a standardized protocol which was adopted and modified from our previous study. Under his management protocol, the mean hospital stay was 1.6 days. Flexible oesophagoscopy under local anaesthesia, and rigid oesophagoscopy under general anaesthesia, were performed in 1.5 per cent and 7.7 per cent of cases respectively. Major complications including oesophageal perforation and deep neck abscesses occurred in 0.19 per cent of patients. There was no mortality. This management protocol for ingested foreign bodies was both safe and cost-effective when compared to similar studies reported in the literature.

Adolescent↗
PubMed2001

Role of endothelin in diabetic vascular complications.

Endothelin-1 (ET-1), a 21 amino acid peptide originally purified from conditioned medium of cultures of porcine aortic endothelial cells, is recognized as a product of many other cells as well. It is now known that there are three endothelin genes in the human genome (ET-1, ET-2, and ET-3). ET-1 and ET-2 are both strong vasoconstrictors, whereas ET-3 is a potentially weaker vasoconstrictor than the other two isoforms. Besides being the most potent vasoconstrictor yet known, ET-1 also acts as a mitogen on the vascular smooth muscle, and, thus, it may play a role in the development of vascular diseases. It is well known that accelerated angiopathy is a major complication in diabetes mellitus. As generalized endothelial cell damage is thought to occur in diabetic patients, ET-1, being released from the damaged endothelial cells, is able to make contact with the underlying vascular smooth muscle cells and thus could be one important cause of diabetic angiopathy. This article summarizes the reported literature of the role of ET-1 in the development of diabetic complications, with particular focus on the possible role of ET-1 in mediating the effects of angiotensin-converting enzyme inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Prognostic factors of hyperglycemic hyperosmolar nonketotic state.

BACKGROUND: To delineate the prognostic factors of patients suffering from hyperglycemic hyperosmolar nonketotic state (HHNK) in Taiwan. METHODS: We reviewed the charts of patients who had been admitted to the Division of Endocrinology and Metabolism of Kaohsiung Veterans General Hospital from 1992 to 1998 due to HHNK. General and clinical data were collected. The influential factors for prognosis were determined. RESULTS: One hundred and nineteen patients fulfilling the criteria of HHNK were included in our study. The mean age was 67.8 +/- 11.7 years with male predominance. Twenty-nine patients died which produced a fatality rate of 24.4%. Eighty-six (72.3%) cases occurred in patients with known diabetic history, while another thirty-three (27.7%) occurred in patients with no diabetic history. Most patients received oral antidiabetic drugs before HHNK episodes. The patients who died had shorter length of inpatient stay than did survivors. The leading precipitating factor was infection (57.1%), followed by poor compliance of medication (21.0%) and undiagnosed diabetes (10.9%). Fifty patients (42%) had a history of stroke. The risk factors for death included precipitation of HHNK by infection and low Glasgow coma scale (GCS) on admission. Old age itself did not contribute to death. Severity of hyperglycemia or hyperosmolarity was also not an important prognostic factor. Multiple logistic regression revealed that low GCS on admission was the most influential factor of leading to death. Most of the patients who died did so due to underlying precipitating factors. CONCLUSIONS: Neither age nor osmolarity, but underlying precipitating factors and state of consciousness were the most influential factors affecting the prognosis of HHNK.

Adult↗
PubMed2000

Epiglottic cyst.

Explore the source record for details and available documents.

Cysts↗
PubMed2000

Plasma endothelin levels are unaltered by thyroid hormone status in humans.

Endothelin is a novel potent vasoconstrictor peptide produced by a wide variety of cell types and which has diverse biological activities. Previously we have reported that thyroid hormone status alters tissue levels of immunoreactive endothelin (irET) in rats. In order to study whether plasma irET levels in humans are affected by thyroid hormone status, we measured irET concentrations by means of radioimmunoassay in plasma samples from euthyroid controls as well as from patients with either hypothyroidism or hyperthyroidism. Plasma samples from the above-mentioned three groups of subjects were collected. After extraction with Sep-Pak C18 cartridges, plasma irET levels were measured by radioimmunoassay. The plasma irET levels in the three groups of subjects did not show any significant difference. Also, no correlations were found between plasma irET levels, thyroid hormones and the thyroid-stimulating hormone thyrotropin (TSH) in euthyroid, hypothyroid and hyperthyroid subjects. These results suggest that thyroid function per se is not a major determinant of plasma irET levels in humans.

Adult↗
PubMed2000

Detection and characterization of endothelin in transformed human osteoblast cell culture medium.

Endothelin-1 (ET-1), a 21 amino acid peptide originally purified from conditioned medium of cultures of porcine aortic endothelial cells, is recognized also as a product of many other cells such as epithelial cells, glial cells, and neurons. It is now recognized that at least ET-1 plays an important role in bone metabolism. It has been shown that ET-1 inhibits osteoclast bone resorption by a direct effect on cell motility and it can also activate phospholipase C in the osteoblast. Furthermore, several studies have shown that ET-1 stimulates the formation of inositol phosphates, the synthesis of DNA, the mobilization of calcium from extra- and intracellular pools, the activation of phospholipase D, and the stimulation of tyrosine phosphorylation in osteoblast-like (MC3T3-E1 and UMR-106) cells. The aim of the present study was to detect and characterize the presence of endothelin in transformed human osteoblast cell culture medium (HTb96) by radioimmunoassay and chromatography methods. Immunoreactive endothelin (IR-ET) was undetectable in the medium incubated at 0.5 and 1 h and was 3.2 +/- 0.2 fmol/10(5) cells (mean +/- SEM, n = 6) at 2 h, 9.5 +/- 0.5 fmol/10(5) cells at 6 h, 19.8 +/- 2.1 fmol/10(5) cells at 24 h, and 23.7 +/- 2.0 fmol/10(5) cells at 48 h, respectively. Sephadex G-25 superfine chromatography and fast protein liquid chromatography studies showed that >90% of IR-ET in the culture medium coeluted with synthetic ET-1. These results show that ET-1 could be formed by transformed human osteoblasts. Further studies should be conducted to elucidate the physiological role of endothelins as possible autocrine, paracrine, or endocrine factors in calcium and bone metabolism.

Cell Line, Transformed↗
PubMed1998

Is captopril-induced improvement of insulin sensitivity mediated via endothelin?

Angiotensin-converting enzyme (ACE) inhibitors have been reported to improve insulin sensitivity during either short-term or long-term administration. Recent studies indicate that endothelin-1 (ET-1) has potent glycogenolytic effects in rat hepatocytes and may cause insulin resistance in rat adipocytes. In addition, ET may also have a role in stimulation of the hypothalamic-pituitary-adrenal axis. To test the hypothesis that part of the effect of captopril in enhancing insulin sensitivity may be mediated via ET and/or by glucocorticoids, we measured 24-h urinary excretion of ET and free cortisol before and after short-term treatment with captopril. The 24-h urinary immunoreactive endothelin (IR-ET) excretion decreased significantly (p < 0.05) from 65 +/- 4 ng at baseline to 42 +/- 3 ng after captopril treatment, whereas no significant change in the 24-h urinary free cortisol excretion was observed. Moreover, no significant change in the 24-h urinary IR-ET and free cortisol excretions was noted in the placebo-treated group. We speculate that ACE inhibitors may exert their effect on insulin sensitivity not only by blocking the renin-angiotensin and kinin systems but also by inhibiting production and/or release of ET.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Serum endothelin and atrial natriuretic peptide in cirrhotic patients with ascites and hepatorenal syndrome.

BACKGROUND: The pathogenesis of cirrhotic ascites and hepatorenal syndrome remains unresolved. The involvement of both endothelin-1 and atrial natriuretic peptide have recently been suggested. This study investigated the concentrations of serum endothelin and atrial natriuretic peptide in cirrhotic patients. METHODS: Seven healthy subjects and 31 cirrhotic patients were studied. Cirrhotic patients were divided into three groups: Group I, 16 cirrhotic patients without ascites; Group II, 10 cirrhotic patients with ascites, but without hepatorenal syndrome; and Group III, five cirrhotic patients with hepatorenal syndrome and ascites. Their sera were analyzed for endothelin-1 and atrial natriuretic peptide concentrations. RESULTS: Cirrhotic patients with ascites, Group II and Group III, had higher plasma endothelin-1 concentrations (15.9 +/- 2.3 pg/ml and 24 +/- 2.1 pg/ml, respectively) than normal subjects and compensated cirrhotics (3.8 +/- 0.7 pg/ml and 6.4 +/- 1.1 pg/ml, respectively); p < 0.001). Atrial natriuretic peptide concentrations were also significantly higher in cirrhotic patients than in normal subjects (p < 0.025). Plasma endothelin-1 concentration had a negative correlation with creatinine clearance (r = -0.65, p < 0.001), as did atrial natriuretic peptide concentrations (r = -0.44, p = 0.012). Plasma endothelin-1 correlated significantly with atrial natriuretic peptide concentrations (r = 0.38, p = 0.035). CONCLUSIONS: Both endothelin-1 and atrial natriuretic peptide concentrations were elevated in cirrhotic patients with ascites and hepatorenal syndrome. Endothelin-1 may have a negative impact on renal function. Our data also suggested that impaired responsiveness rather than impaired secretion of atrial natriuretic peptide is responsible for sodium retention in cirrhotic patients with ascites.

Adult↗
PubMed1996

Thoracoscopic lobectomy for an infected intrapulmonary bronchogenic cyst.

A 19-year-old male who presented with cough and fever was found to have an 8-cm cyst in his left lung. Video-assisted thoracoscopic left lower lobectomy was performed. The cyst had to be decompressed by needle aspiration prior to retrieval through a 5-cm minithoracotomy. The patient was discharged on postoperative day 4 in good condition. The technical aspects form the basis of this report.

Adult↗
PubMed1996

Late-onset idiopathic hypoparathyroidism with thymoma: a case report.

A 62-year-old male was admitted because of numbness and twitching of both hands. Hypocalcemia with positive Trousseau's sign was noted. Chest X-ray and computed tomography (CT) showed an anterior mediastinal mass. Skull X-ray and whole body bone scan could not rule out bony metastasis to the left parietal bone, causing an anterior mediastinal tumor with bony metastasis to be suspected initially. Median sternotomy and extended thymectomy were done, and Stage II thymoma with negative calcitonin staining was noted. However, hypocalcemia persisted after thymectomy and the results of pre-operative and post-operative intact-parathyroid hormone (intact-PTH) were less than the detection limit (<13.3 pg/ml). Tumor markers and gallium tumor scan were all negative. Brain CT disclosed calcification over the bilateral basal ganglia and bilateral dentate nuclei of the cerebellum; the supposed metastatic osteolytic lesions of parietal bone were considered to result from pacchionion arachnoid granulation tissues. The coexistence of late-onset idiopathic hypoparathyroidism and thymoma has not been reported before. Long-term replacement therapy with vitamin D and calcium was necessary for this case.

Humans↗
PubMed1995

MELAS syndrome associated with diabetes mellitus and hyperthyroidism: a case report from Taiwan.

MELAS syndrome is a form of mitochondrial myopathy with manifestations of seizure, stroke-like syndrome, lactic acidosis, ragged red muscle fibres and mitochondrial encephalopathy. The syndrome has been reported in association with a variety of endocrine and metabolic disorders including diabetes mellitus (DM), hypothalamo-pituitary hypofunction, hypothalamic growth hormone deficiency and delayed puberty. Mitochondrial DNA (mtDNA) point mutation may be the major pathological defect. However, association of MELAS syndrome with hyperthyroidism has not previously been reported. A case is reported from Taiwan of a 32-year-old woman suffering from MELAS syndrome with associated DM and hyperthyroidism. When the latter was diagnosed in April 1988, the patient underwent subtotal thyroidectomy. There was no family history of thyroid disease. Because of repeated seizures, she had computed tomography (CT) and magnetic resonance imaging (MRI) of the brain which showed focal, low-density lesions over the cerebral hemispheres. Both serum and cerebral spinal fluid lactic acid levels were elevated. Mild elevations of serum T4 and T3 and a high titre of TSH receptor antibody were still present. Hyperglycaemia was noted during hospitalization and DM confirmed by oral glucose tolerance test. Muscle biopsy showed ragged red fibres. DNA analysis showed an A-to-G transition at the 3243rd nucleotide position of the tRNA(Leu(UUR)) gene of the mtDNA from the patient. Quantitative polymerase chain reaction (PCR) and restriction analysis revealed that about 60% of the blood mtDNA was of mutant type. The patient received antithyroid drugs for hyperthyroidism, diet control for DM and anti-epileptic drugs for seizure.

Adult↗
PubMed1995

Does endothelin play a role in the pathogenesis of early diabetic nephropathy?

Endothelin-1 (ET-1) causes dramatic vasoconstriction and reduction of renal blood flow, with a decreased glomerular filtration rate (GFR). Early diabetic nephropathy is characterized by elevation of GFR and the formation of intrarenal microaneurysms. However, the mechanisms are unclear. To elucidate the pathophysiologic significance of urinary ET-1 in early diabetic nephropathy, the 24-h urinary excretion of ET-1 in 12 normal subjects and 20 patients with newly diagnosed type 2 diabetes mellitus were determined by a highly sensitive radioimmunoassay. The 24-h urinary ET-1 excretion in patients with diabetes mellitus (14.2 +/- 3.1 pmol, mean +/- SEM) was significantly lower (p < 0.05) than that of normal subjects (25.0 +/- 3.7 pmol). This decrease in urinary excretion of ET-1 in patients with recent-onset diabetes mellitus suggests a possible role of ET-1 in the pathogenesis of early diabetic nephropathy.

Adult↗
PubMed1994

Factors affecting the labor efficiency of hospital-based blood bank laboratories.

BACKGROUND: A variety of financing mechanisms and managerial innovations have been developed in the past decade to control hospital costs. Some evidence suggests that those changes have not produced substantial improvements in labor efficiency among employees in the hospital's technical level, such as in the blood bank laboratories. STUDY DESIGN AND METHODS: This study measured labor efficiency in 40 hospital-based blood bank laboratories in Southern California during the year from July 1989 to June 1990 and explored the impact of financial, managerial, and operational factors on labor efficiency. RESULTS: With standardized output measures used in all blood bank laboratories, a wide variation of labor efficiency was found. Multivariate analyses indicate that the labor efficiency of blood bank employees was not influenced by organizational financial incentives, but was affected by the managerial styles of blood bank managers. CONCLUSION: Interpretation of the findings suggests that labor efficiency is affected by operational designs intended to improve responses to variable workloads and reduce slack time.

Blood Banks↗
PubMed1994

Insulin autoimmune syndrome in a patient with methimazole and carbimazole-treated Graves' disease: a case report.

Insulin autoimmune syndrome (IAS) includes fasting or reactive hypoglycemia, hyperinsulinemia and the presence of insulin-binding antibodies in patients who have never been exposed to exogenous insulin. The report concerns a 34-year-old male patient with Graves' disease who had history of having taken methimazole for two months, without any consequence, 4 years previously. However, when methimazole was again administered for three weeks followed by a week of carbimazole, the patient suffered hypoglycemia 4 times during the next 4 weeks. He denied history of diabetes mellitus (DM), of taking any oral hypoglycemic agent or of having received insulin injection. Laboratory data showed total serum insulin level > 320 microU/mL, free insulin 55 microU/mL and insulin antibody 88.3%. Oral glucose tolerance test (OGTT) revealed DM pattern. Since the patient had history of allergy to anti-thyroid drugs before this event, so he was treated with radioiodine (131I). There was no episode of hypoglycemic attack during 15 months of follow-up.

Adult↗
PubMed1993

The lung contents of endothelin are altered by thyroid hormone status in rat.

Endothelin-1 (ET-1) is a 21-residue peptide isolated from the conditioned medium of cultured porcine endothelial cells and is widely distributed throughout the body, with relatively high levels in the kidney and lung. Animal studies have revealed that the lung appears to have the largest capacity for ET-1 removal from the blood stream. In this study we have examined the possible influence of thyroid status on immunoreactive endothelin (IR-ET) levels in the plasma and lung of the male rats. 3 weeks after the surgical removal of the thyroid gland from male rats, the IR-ET levels in the lung were reduced by 39%. Similarly, IR-ET levels were decreased 46% in the lung of rats rendered hypothyroid by treatment with 0.1% (w/w) PTU in the drinking water for 30 days, and replacement with daily L-thyroxine (T4) injections (5 micrograms/100 g) prevented this decrease. However, thyrotoxicosis induced by daily L-T4 injections (10 micrograms/100 g) also caused a decrease of the lung IR-ET levels by 49%. Nevertheless, the plasma IR-ET levels are similar in each group. Fast protein liquid chromatography study verified the presence of ET-1 immunoreactivity in both rat plasma and lung tissue extracts. This study demonstrates that euthyroid status is required for the maintenance of physiological concentrations of IR-ET in the lung of male rats.

Animals↗