Biomedical subjects

K C Loh

Publications and source records attributed to K C Loh.

At least 55 records · Page 3Linked to original sources

PubMed1997

Familial papillary thyroid cancer: a case report.

Familial occurrence of medullary thyroid cancer is well known in families as an isolated malignancy or in association with multiple endocrine neoplasia syndrome type II. Conversely, papillary thyroid cancer almost always presents sporadically except for reports of familial clustering in individuals with radiation exposure, inherited syndromes of colonic polyposis or multiple harmatomas, and rarely in monozygotic twins. We report a case of papillary thyroid cancer diagnosed incidentally in a 53-year-old woman who underwent surgery for excision of an adenomatous nodule. It was noted that her mother suffered from a similar thyroid malignancy some 33 years ago, and several of her maternal relatives had either Graves' disease or hypothyroidism. The possible existence of this familial entity and its likely genetic basis is discussed.

Biopsy, Needle↗

PubMed1996

Spontaneous remission of ectopic Cushing's syndrome due to pheochromocytoma: a case report.

A young female adult with Cushing's syndrome arising from ectopic production of corticotropin (ACTH) from an adrenal pheochromocytoma showed spontaneous clinical and biochemical remission of hypercortisolism after a brief period of ketoconazole administration. Despite continued remission of the hypercortisolism over the next 18 months, there was progressive catecholamine hypersecretion with significant morbidity as a result of the pheochromocytoma. Surgical resection of the left adrenal gland revealed a pheochromocytoma showing focal cytoplasmic immunostaining for ACTH and marked diffuse compact cell hyperplasia in the adrenocortical tissue. To our knowledge this is the first reported case of spontaneous clinical and biochemical remission of ectopic ACTH production from a pheochromocytoma. The pathogenesis of the remission remains unknown.

ACTH Syndrome, Ectopic↗

PubMed1996

Murine typhus: a forgotten cause of febrile illness in Singapore.

We report 6 cases of marine typhus presented to us within a period of 3 months. The diagnoses were made based on the Weil-Felix reaction in the context of supportive clinical and epidemiological features, and response to appropriate antimicrobial therapy. This review serves to remind us that murine typhus is still an important cause of acute febrile illness in Singapore, especially among the migrant Indian workers.

Acute Disease↗

PubMed1996

High prevalence of dyslipidaemia despite adequate glycaemic control in patients with diabetes.

Forty-seven patients with newly diagnosed diabetes were followed up for 1 year with lipid parameters (total cholesterol, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol and triglycerides) and glycated haemoglobin measured at diagnosis and 6-monthly intervals. The prevalence of these lipid parameters exceeding the risk level for coronary heart disease at diagnosis ranged from 34% to 64%, the commonest dyslipidaemic pattern being hypercholesterolaemia (43%), followed by mixed hyperlipidaemia (17%) and hypertriglyceridaemia (17%). There was no improvement in the lipids profile over a 1-year period despite achieving good glycaemic control in both the insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) patients. Twenty-four (51%) patients will need lipid lowering treatment because of persistent dyslipidaemia despite adequate non-pharmacologic measures. We suggest that an active strategy of early detection and drug treatment for dyslipidaemia is needed for patients with diabetes mellitus.

Adolescent↗

PubMed1996

Large macroprolactinoma treated with bromocriptine alone.

We report a case of a large macroprolactinoma in a 44-year-old male photographer who presented with affected colour perception and a central scotoma of the right eye. An initial computerised tomographic (CT) scan showed an enormous mass lesion extending from the nasopharyngeal area to the third ventricle, with destruction of the skull base. The initial serum prolactin level was 29 180 micrograms/L (normal < 15.8 micrograms/L) while other pituitary hormones were within normal ranges. The patient was treated with oral bromocriptine with prompt resolution of visual defects while significant reductions in tumour size (> 50%) and prolactin level (> 99%) were achieved over a one-year period. This represents one of the highest serum prolactin levels reported in the literature in a patient with a prolactin-secreting pituitary tumour and illustrates the remarkable efficacy of dopamine agonist therapy in patients with large macroprolactinomas.

Administration, Oral↗

PubMed1996

Reverse cholesterol transport: its contribution to cholesterol catabolism in normal and disease states.

OBJECTIVES: To review the reverse cholesterol transport (RCT) model and its contribution to cholesterol catabolism in normal and disease states. DATA SOURCES: Pertinent articles were identified through a MEDLINE search of the English language literature from 1983 to 1995, followed by a manual search of the bibliographies of pertinent articles. STUDY SELECTION: Review articles, laboratory and clinical studies and case reports. DATA EXTRACTION: The physiology of the RCT pathway as well as alterations observed in individuals with diseases or lifestyle changes were reviewed. DATA SYNTHESIS: Data were derived mainly from laboratory studies and clinical observations. The RCT model is proposed to explain the removal of excess cholesterol from extrahepatic tissues and its delivery to liver for catabolism. This involves several regulated steps mediated by the plasma apolipoproteins and two key enzymes, lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP). In essence free cholesterol in peripheral tissues is taken up by nascent high density lipoprotein (HDL) particles, converted to cholesteryl esters (by LCAT), and then transferred to apo B-containing lipoproteins (by CETP) for hepatic removal. Altered cholesterol catabolism may occur in individuals with disorders of a genetic or acquired nature as well as lifestyle changes, as a result of alterations in one of several of the putative steps or enzymes involved in RCT. CONCLUSIONS: The proposed antiatherogenic role of RCT remains to be validated as a review of the possible alterations noted in various disorders showed conflicting results in atherogenic propensity.

Apolipoproteins↗

PubMed1995

A serotype-specific epitope of dengue virus 1 identified by phage displayed random peptide library.

From a panel of monoclonal antibodies of dengue viruses, a serotype-specific epitope of dengue virus 1 was screened from a random peptide library displayed on phage. The epitope was the determinant reactive with monoclonal antibody 15F3-1 that was specific to dengue 1. The screening was monitored by a dot blotting procedure, and after three rounds of screening a consensus motif, HRYSWK, was found. This sequence matches the sequence HKYSWK, corresponding to the amino acid residues 885-890 of polyprotein or residues 111-116 of the non-structural protein 1 of dengue virus serotype 1. The linear epitope was confirmed by testing the antigenicity of chemically synthesized 8-branched peptide.

Amino Acid Sequence↗

PubMed1995

Analysis of recombinant human tumor necrosis factor beta by capillary electrophoresis.

Capillary electrophoresis was used for the analysis of recombinant human tumor necrosis factor beta (rhTNF-beta). Reproducible separation of the protein could be achieved in Polybrene-coated capillaries. Optimum conditions for separation were achieved with a pH 4.5 sodium acetate buffer. Besides Polybrene-coated capillaries, other commercially available column and column-coating reagents were also examined for the separation of rhTNF-beta. Capillary electrophoresis was found to be a potentially useful method for product analysis and process monitoring in recombinant-DNA technology.

Electrophoresis↗

PubMed1995

Primary systemic allergy to human insulin: recurrence of generalized urticaria after successful desensitization.

Primary systemic allergy to human insulin is rare. We report a case of recurrent immediate local reactions followed eventually by generalized urticaria to recombinant human insulin (Humulin) in an insulin-dependent diabetic. Skin test to Humulin R was positive, and the patient was successfully desensitized using a modified rapid desensitization protocol. Two weeks later, he had another episode of generalized urticaria after Humulin R injection. His treatment was resumed at a lower dose, and within a week he was able to tolerate his usual regimen of insulin. To our knowledge, this is the first report of a recurrence of systemic reaction after successful desensitization.

Adult↗

PubMed1995

Case of pulmonary alveolar proteinosis treated by sequential whole-lung lavages and a review of the condition.

We report our first local case of pulmonary alveolar proteinosis that required symptomatic therapy with whole lung lavage. This is a rare condition associated with the accumulation of phospholipid material in the alveoli. The presentation is usually insidious and the symptomatology varies from vague complaints to severe crippling dyspnoea. The diagnosis is often delayed and usually made after the exclusion of other conditions. While there is no definitive treatment apart from lung transplant, whole-lung lavage is a safe, repeatable procedure which offers the best prospect for symptomatic, physiological and radiological improvement in severe cases.

Adult↗

PubMed1995

Prevalence and prognostic relevance of sick euthyroid syndrome in a medical intensive care unit.

The prevalence and prognostic relevance of alterations in thyroid function indices in 100 critically ill patients were evaluated prospectively on admission to our medical intensive care unit (MICU). Patients with a present or past history of thyroid disorder and those on drugs that might interfere with thyroid function indices were excluded. Eighty-four (84%) of the patients had altered thyroid function indices suggestive of sick euthyroid syndrome (SES). The overall mortality rate for patients with and without evidence of SES were 40% and 6% respectively (P < 0.01). Serum total 3,3',5-triiodothyronine (T3) and total thyroxine (T4) concentrations were reduced in 67% and 24% of the patients respectively. The low T3 state and the low T3 and T4 state accounted for 55% and 29% of the SES cases respectively. No correlation was noted between the serum T4 concentration and survival outcome while a normal serum T3 value served as a good predictor for survival (97%). However, routine study of thyroid function indices in critically ill patients for its prognostic value is not encouraged as results are often heterogenous due to various limitations which will be discussed.

Adolescent↗

PubMed1995

Primary hyperparathyroidism: a case with severe skeletal manifestations.

Over the years, patients with primary hyperparathyroidism are often asymptomatic and diagnosis is suspected on the incidental finding of hypercalcaemia. We report a patient, a middle-aged man from northern Sumatra, with a florid but uncommon presentation of severe bone pains and bilateral femoral neck fractures. He was found to have a solitary parathyroid adenoma which was successfully removed surgically. Postoperatively, the patient had severe symptomatic hypocalcaemia that required aggressive replacement therapy with calcium, magnesium and active vitamin D. He was well clinically and had significant improvement of biochemical indices on follow-up at 3 months. This report is followed by a review on the management of this condition.

Adenoma↗

PubMed1994

Antibody against branched epitope as an affinity ligand to separate the parent protein.

A peptide that contained one of the continuous epitopes of recombinant human lymphotoxin (rhLT) (amino acid residues 139-154) has been located by epitope mapping. The branched form of this peptide was synthesized by the multiple antigen peptide procedure with an octameric branched resin and was subsequently used to elicit anti-epitope antibody in rabbits. The resulting anti-epitope was then used as an immunoaffinity ligand in affinity chromatography to purify the parent protein, rhLT, from the host cell lysate directly. It is suggested that this approach would be a general way to create novel biospecific ligands for affinity separations.

Amino Acid Sequence↗

PubMed1994

Rapid purification of recombinant human tumor necrosis factor beta.

A rapid and improved method for the purification of recombinant human tumor necrosis factor beta (rhTNF-beta) from Escherichia coli HB 101 cells has been developed. The method utilized sequential steps of polyethylenimine (PEI) and ammonium sulfate precipitation to remove most of the extraneous proteins and nucleic acids from the cell extracts. The final step of purification consisted of DEAE-Sepharose chromatography at pH 7.5 in which rhTNF-beta was eluted with starting buffer. This procedure, when compared to the earlier methods of purification, is highly efficient since we could increase the overall yield of rhTNF-beta and reduce the purification time considerably. The final yield that we obtained from 1 liter of fermentation broth (containing approximately 80 g of wet cells) was 40-50 mg.

Amino Acid Sequence↗

PubMed1994

Continuous epitopes of human lymphotoxin and their topographies.

Human lymphotoxin (hLT or TNF-beta) is a lymphokine that is structurally and functionally related to tumor necrosis factor alpha (TNF-alpha). The continuous epitopes of hLT were located by examining the cross-reaction between rabbit anti-hLT antibody and peptides derived from proteolytic digestion and chemical synthesis. Three antigenic sites, corresponding to residues 40-48, 83-94 and 139-147, of the protein sequence, were located by this approach. Since residues 49-57 also exhibited trace antigenicity, but residues 45-52 displayed no reaction, the whole peptide fragment consisting of residues 40-57 might be necessary for antigenicity. A comparison of the antigenic determinants with the loop structures obtained from X-ray crystallographic studies of hLT showed that all of the epitopes are found on or adjacent to functionally important domains.

Amino Acid Sequence↗

PubMed1994

Primary pulmonary lymphoma: report of three cases and a brief review of the literature.

We report three patients with primary pulmonary non-Hodgkin's lymphoma which is a rare extranodal lymphoid neoplasm. In these patients, both the history and physical findings were vague and minimal. The laboratory findings were normal apart from chest radiographic abnormalities and serum gammopathy in two cases. All three patients underwent several diagnostic procedures before conclusive results were obtained from thoracotomy specimens. Histology revealed small lymphocytic infiltrate of the pulmonary parenchyma with nodal involvement in all three cases. All three patients had surgical resection and two received adjuvant chemotherapy. They are all alive and symptom-free at 92, 51 and 12 months, respectively, after diagnosis.

Diagnosis, Differential↗

PubMed1992

Intracellular localization of human DNA repair enzyme methylguanine-DNA methyltransferase by antibodies and its importance.

The human DNA repair enzyme, methylguanine-DNA methyltransferase (MGMT, M(r) 21,000), which protects cells against the mutagenic effect of alkylating carcinogens, was found to be localized in the cell nucleus (except the nucleolus) by immunofluorescence staining using polyclonal and monoclonal antibodies. The supporting experiments came from differential staining of the MGMT-deficient (mer-) and -proficient (mer+) cells, Western blotting analysis, and specific antibody depletion studies with the immobilized fusion protein, GSTMGMT-glutathione-Sepharose. Its localization in the nucleus agrees with its biological function and possibly explains the ineffective protection of mammalian cells (mer-) transfected with the Escherichia coli MGMT genes from bifunctional alkylating agents.

Amino Acid Sequence↗

PubMedDate not supplied

Enhancement of biodegradation of phenol and a nongrowth substrate 4-chlorophenol by medium augmentation with conventional carbon sources.

The enhancement of biodegradation of phenol and 4-chlorophenol (4-cp) as a cometabolised compound by Pseudomonas putida ATCC 49451 was accomplished by augmenting the medium with conventional carbon sources such as sodium glutamate and glucose. Compared with phenol as the sole carbon source, the addition of 1 gl(-1) sodium glutamate increased the toxicity tolerance of cells toward 4-cp and significantly improved the biodegradation rates of both phenol and 4-cp even when the initial concentration of 4-cp was as high as 200 mgl(-1). On the other hand, supplementation of glucose caused a significant drop in the medium pH from 7.2 to 4.3 resulting in a reduction of degradation rate, leaving a considerable amount of 4-cp undegraded when the initial concentration of 4-cp was higher than 100 mgl(-1). By regulating the pH of the medium, however, enhancement of degradation rates of phenol and 4-cp in the presence of glucose was achieved with a concomitant complete degradation of phenol and 4-cp.

Biodegradation, Environmental↗