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Biomedical subjects

L K Tan

Publications and source records attributed to L K Tan.

At least 91 records · Page 5Linked to original sources
PubMed1986

Innervation of periesophageal region of cat's diaphragm: implication for studies of control of vomiting.

The extent of the region of the diaphragm around the esophagus that displays greatly reduced activity during the expulsive phase of vomiting was determined from electromyographic studies in cats to be about 0.75-1.0 cm from the esophagus. Horseradish peroxidase injected into this region retrogradely labeled motoneurons throughout most of the rostral-caudal extent of the phrenic nucleus, with the exception of caudal C6 and rostral C7. This widespread intermingling of motoneurons that innervate the region of reduced activity with other phrenic motoneurons creates a difficulty for needed follow-up studies of diaphragmatic control during vomiting.

Abdominal Muscles↗
PubMed1986

A comparison of iohexol and iopamidol for lumbar myelography.

The use of iopamidol and iohexol for lumbar myelography is compared in this study. Fifty-eight patients were examined, the contrast media being allocated on a randomised double-blind basis. Radiographic quality was good with both media. Headache and an increase of back pain were the most frequent symptoms, though the incidence of side-effects was slightly but significantly greater with iohexol. We conclude from our study that while the radiographic quality is comparable, iopamidol seems to be slightly better tolerated.

Adult↗
PubMed1986

Systemic to pulmonary artery fistulas in Hodgkin's disease.

A case of Hodgkin's disease with multiple systemic to pulmonary artery fistulas is described. Despite resolution of the parenchymal infiltrate with combination chemotherapy, the vascular abnormalities persisted. Successful closure of the vascular connections occurred after therapeutic embolization with gel foam and alcohol.

Adult↗
PubMed1986

Adrenal phaeochromocytoma and neurofibromatosis presenting with hypotension.

We report a case of adrenal phaeochromocytoma with the stigmata of neurofibromatosis, who presented with acute hypotension. The patient later had episodes of hypertension alternating with hypotension, associated with electrocardiographic changes simulating myocardial infarction, and finally a completed stroke. The circumstances illustrate the problem of early recognition of the protean clinical effects of an excess of circulating adrenal medullary hormones. They also emphasise the need to consider phaeochromocytoma as a differential diagnosis of apparent clinical shock.

Adrenal Gland Neoplasms↗
PubMed1985

Low plasma renin activity in diabetes. Relation to urine prostaglandin excretion.

Renal functional abnormalities, occurring before overt renal disease and possibly due to abnormal vascular control mechanisms, have been described in diabetes mellitus. We used intravenous (i.v.) furosemide, which stimulates renal prostaglandin (PG) synthesis and renin release, to compare these vasoactive systems in 14 diabetic and 23 normal control subjects. Using urine thromboxane B2 (TXB2) as an index of renal synthesis of the vasoconstrictor prostanoid TXA2, and urine 6keto-PGF1 alpha for the vasodilator PGI2, we found evidence of increased renal TXA2 synthesis in diabetic subjects in response to furosemide. The increased TXA2 synthesis did not occur at the expense of PGI2 synthesis, as urine 6keto-PGF1 alpha was not reduced. Increased TXB2 excretion in diabetic subjects was particularly marked in the first 10 min after i.v. furosemide. During this time, diabetic males excreted 31 +/- 6 ng of TXB2 compared with 10 +/- 1 ng for normal males (P less than 0.05), while diabetic females excreted 15 +/- 3 ng compared with 7 +/- 1 ng for normal females (P less than 0.05). Also, 6keto-PGF1 alpha excretion at 10 min was increased in diabetic subjects: males, 29 +/- 3 ng versus 19 +/- 3 (P less than 0.05); females, 33 +/- 8 versus 16 +/- 3 (P less than 0.05). The ratio of TXB2 to 6keto-PGF1 alpha tended to be higher in diabetic males.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1985

A human-mouse chimeric immunoglobulin gene with a human variable region is expressed in mouse myeloma cells.

We have constructed and obtained expression of a chimeric human-mouse immunoglobulin gene after transfection into mouse myeloma cells. A human VDJH gene segment was joined to a mouse C kappa gene in the plasmid vector pSV2-gpt, and the construct was transfected into J558L cells by protoplast fusion. Analyses of six transformants by RIA and SDS-PAGE indicated that the chimeric protein was synthesized in large amounts in five. A kappa-specific transcript was observed by Northern blot analysis. Four out of five clones were stable producers of this chimeric chain over a period of 10 mo.

Animals↗
PubMed1984

Designing education interventions to improve physician performance in office practice.

Family doctors play a very important role in determining the health of the populace; however, surveys and expert opinions indicate that there is considerable room for improvement in the knowledge and skills of family physicians concerning the prevention, early detection and management of the major causes of death and disability. Effective Continuing Medical Education (CME) could help greatly to resolve this problem. THere is, however, little evidence that presently available systems of CME, though costly, are effective in improving either physician competence or patient health. Attractive and cost-effective CME methods are greatly needed. This study develops, field tests and evaluates more efficient office-based CME programs for family doctors. Prevention, early detection and improved management of cardiovascular disease and cancer are the primary goals. A pretest posttest control group and time series approach was chosen for the experimental design. Thirty-one family physicians are participating. Physician performance and patient outcome prior to and after education are being assessed largely through office record review.

Education, Medical, Continuing↗
PubMed1984

Genito-urinary tuberculosis--a local experience on its diagnosis and management.

Though the incidence of pulmonary tuberculosis has been on the decline, the incidence of genito-urinary tuberculosis has not decreased proportionately as the majority of patients have no associated pulmonary tuberculosis. Genito-urinary tuberculosis affects male and female equally and is commonest in the 4th decade of life. The most frequent presentation is that of persistent urinary tract infection in 2/3 of patients and gross haematuria in about 1/3 of our patients. A few may be relatively asymptomatic with loin ache. Though urine culture for acid-fast bacilli is important, diagnosis in most patients was established on histopathology and typical radiological features. The main stay of treatment is medical. The role of surgery is mainly reconstructive, to overcome strictures causing obstruction so as to preserve renal function. Close cooperation between physician and surgeon is important in the management of this disease.

Adult↗
PubMed1983

Nucleotide sequence of the cDNA encoding the precursor of the beta subunit of rat lutropin.

We have determined the nucleotide sequences of cDNAs encoding the precursor of the beta subunit of rat lutropin, a polypeptide hormone that regulates gonadal function, including the development of gametes and the production of steroid sex hormones. The cDNAs were prepared from poly(A)+ RNA derived from the pituitary glands of rats 4 weeks after ovariectomy and were cloned in bacterial plasmids. Bacterial colonies containing transfected plasmids were screened by hybridization with a 32P-labeled cDNA encoding the beta subunit of human chorionic gonadotropin, a protein that is related in structure to lutropin. Several recombinant plasmids were detected that by nucleotide sequence analyses contained coding sequences for the precursor of the beta subunit of lutropin. Complete determination of the nucleotide sequences of these cDNAs, as well as of cDNA reverse-transcribed from pituitary poly(A)+ RNA by using a synthetic pentadecanucleotide as a primer of RNA, provided the entire 141-codon sequence of the precursor of the beta subunit of rat lutropin. The precursor consists of a 20 amino acid leader (signal) peptide and an apoprotein of 121 amino acids. The amino acid sequence of the rat lutropin beta subunit shows similarity to the beta subunits of the ovine/bovine, porcine, and human lutropins (81, 86, and 74% of amino acids identical, respectively). Blot hybridization of pituitary RNAs separated by electrophoresis on agarose gels showed that the mRNA encoding the lutropin beta subunit consists of approximately 700 bases. The availability of cDNAs for both the alpha and beta subunits of lutropin will facilitate studies of the regulation of lutropin expression.

Amino Acid Sequence↗
PubMed1983

Successful angioplasty of renal artery stenosis due to aorto-arteritis.

A 24-year-old Chinese female who suffered from hypertension and acute myocardial infarction was found to have aorto-arteritis on angiographic examination, with total occlusion of her right coronary artery and subtotal occlusion of her right renal artery. Transluminal angioplasty of her right renal artery was successfully performed and this normalized her blood pressure from 165/105 to 135/85 mm Hg.

Adult↗
PubMed1983

The recurrence of intracranial meningiomas after surgical treatment.

A study of 114 surgically treated patients with intracranial meningiomas was carried out to evaluate factors influencing recurrence. The data of the initial surgery extended over a 24-year period from January, 1956, to December, 1979. The patients ranged in age from 1 1/2 years to 82 years. Seventy-one (62.3%) were females and 43 (37.7%) were males. The surgical procedure was graded according to Simpson's classification from 1 to 5 (Grade 1 = complete excision, Grade 5 = simple decompression). In this series, 33 procedures (28.9%) were Grade 1, 55 (48.2%) were Grade 2, seven (6.1%) were Grade 3, 18 (15.8%) were Grade 4, and one (0.9%) was Grade 5. There were eight (7%) postoperative deaths. Approximately 60% of the tumors were located in the sphenoid wing (23.7%), convexity (21.1%), and parasagittally (14.9%). Histological diagnosis in 96% of the patients was transitional (42.1%), syncytial (34.2%), and fibroblastic (20.2%) meningiomas. Eight (7%) patients received postoperative radiotherapy. There was evidence of recurrence in 22 patients (19.3%). Twenty-one underwent a second surgical procedure. Using survival analysis, it was determined that 80% of the patients were free of recurrence 5 years after the initial surgery, and approximately 50% showed no recurrence 20 years after the initial surgery. Only the grade of the initial surgery had a statistically significant influence on recurrence. Sex of patients, site and histology of the tumor, and postoperative radiotherapy had no statistically significant influence on recurrence. Angioblastic and malignant meningiomas were rare (only four cases), and recurred relatively quickly.

Adolescent↗
PubMed1983

Zollinger-Ellison syndrome--report of four cases and review of literature.

Four patients with Zollinger-Ellison Syndrome (ZES) are presented to highlight the difficulties in the recognition, diagnosis and management of this rare disease. The presentation of ZES is usually indistinguishable from ordinary peptic ulcer disease and in those patients with symptoms not related to peptic ulcer, i.e., diarrhoea, as their main complaint, the diagnosis is often not even considered. A high index of suspicion is required, however, in patients with recurrent ulcers, multiple ulcers and in those with resistant or rapidly relapsing ulcers after conventional therapy. A presumptive diagnosis can be made by the demonstration of grossly elevated fasting serum gastrin levels combined with a secretin stimulation test in doubtful cases. The main problem is the location of the gastrin-secreting tumour which is usually pancreatic but often too small to be detected by currently available techniques. Histamine H2-receptor antagonists in high doses are effective in controlling the gastric acid hypersecretion which is chiefly responsible for the morbidity and mortality in ZES. They provide the treatment of choice in patients where the tumour cannot be located, though every attempt should be made to do this as surgery is the treatment of choice for this invariably malignant tumour. Total gastrectomy is now reserved for those patients in whom medical therapy has failed. The role of chemotherapy in metastatic disease has yet to be established.

Adult↗
PubMed1981

Concentrations and health effects of potash dust.

In an investigation of the relationship between atmospheric dust levels and worker health, the respiratory dust exposures of employees at two Saskatchewan potash mines were examined following atmospheric measurements. Some, notably those of the mining crew and the screening operators, were above the Threshold Limit Value 8-hour Time Weighted Average (TLV-TWA) for total nuisance particulates specified by the American Conference of Governmental Industrial Hygienists (ACGIH). Respiratory symptoms were recorded and forced expiratory lung function tests were done among 850 volunteers drawn from an eligible work force of 931. The results were compared between low and higher exposure groups after allowing for personal factors such as age and smoking habits. Symptoms of Grade I chronic phlegm production and mild shortness of breath and chronic cough were more common in the higher exposure groups, but episodes of chest illness were not. Severe respiratory symptoms were rare. There were no statistically significant differences in the proportions performing lung function tests below predicted values.

Air Pollutants↗