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Biomedical subjects

K M Wong

Publications and source records attributed to K M Wong.

At least 37 records · Page 2Linked to original sources
PubMed1998

Ventricular tachycardia after oxytocin injection in patients with prolonged Q-T interval syndrome--report of two cases.

Oxytocin is widely used in obstetric settings to stimulate uterine contraction and prevent postpartum hemorrhage. Its adverse effects which include transient hypotension and increase heart rate could be life-threatening in patients with fixed cardiac output or hypotension resulting from hemorrhage. We reported two cases suspected to have preexisting prolonged Q-T interval syndrome (PQTS) who developed ventricular tachycardia immediately after intravenous injection of oxytocin. Anesthetic management of and use of oxytocic agents in patients with PQTS were discussed.

Adult↗
PubMed1997

The Northern Marshall Islands Radiological Survey: data and dose assessments.

Fallout from atmospheric nuclear tests, especially from those conducted at the Pacific Proving Grounds between 1946 and 1958, contaminated areas of the Northern Marshall Islands. A radiological survey at some Northern Marshall Islands was conducted from September through November 1978 to evaluate the extent of residual radioactive contamination. The atolls included in the Northern Marshall Islands Radiological Survey (NMIRS) were Likiep, Ailuk, Utirik, Wotho, Ujelang, Taka, Rongelap, Rongerik, Bikar, Ailinginae, and Mejit and Jemo Islands. The original test sites, Bikini and Enewetak Atolls, were also visited on the survey. An aerial survey was conducted to determine the external gamma exposure rate. Terrestrial (soil, food crops, animals, and native vegetation), cistern and well water samples, and marine (sediment, seawater, fish and clams) samples were collected to evaluate radionuclide concentrations in the atoll environment. Samples were processed and analyzed for 137Cs, 90Sr, 239+240Pu and 241Am. The dose from the ingestion pathway was calculated using the radionuclide concentration data and a diet model for local food, marine, and water consumption. The ingestion pathway contributes 70% to 90% of the estimated dose. Approximately 95% of the dose is from 137Cs. 90Sr is the second most significant radionuclide via ingestion. External gamma exposure from 137Cs accounts for about 10% to 30% of the dose. 239+240Pu and 241Am are the major contributors to dose via the inhalation pathway; however, inhalation accounts for only about 1% of the total estimated dose, based on surface soil levels and resuspension studies. All doses are computed for concentrations decay corrected to 1996. The maximum annual effective dose from manmade radionuclides at these atolls ranges from .02 mSv y(-1) to 2.1 mSv y(-1). The background dose in the Marshall Islands is estimated to be 2.4 mSv y(-1). The combined dose from both background and bomb related radionuclides ranges from slightly over 2.4 mSv y(-1) to 4.5 mSv y(-1). The 50-y integral dose ranges from 0.5 to 65 mSv.

Cesium Radioisotopes↗
PubMed1997

Past and present levels of some radionuclides in fish from Bikini and Enewetak Atolls.

Bikini and Enewetak were the sites in the Northern Marshall Islands that were used by the United States as testing grounds for nuclear devices between 1946 and 1958. The testing produced close-in fallout debris that was contaminated with different radionuclides and which entered the aquatic environment. The contaminated lagoon sediments became a reservoir and source term of manmade radionuclides for the resident marine organisms. This report contains a summary of all the available data on the concentrations of 137Cs, 60Co and 207Bi in flesh samples of reef and pelagic fish collected from Bikini and Enewetak Atolls between 1964 and 1995. The selection of these three radionuclides for discussion is based on the fact that these are the only radionuclides that have been routinely detected by gamma spectrometry in flesh samples from all fish for the last 20 y. Flesh from fish is an important source of food in the Marshallese diet. These radionuclides along with the transuranic radionuclides and 90Sr contribute most of the small radiological dose from ingesting marine foods. Some basic relationships among concentrations in different tissues and organs are discussed. The reef fish can be used as indicator species because their body burden is derived from feeding, over a lifetime, within a relatively small contaminated area of the lagoon. Therefore, the emphasis of this report is to use this extensive and unique concentration data base to describe the effective half lives and cycling for the radionuclides in the marine environments during the 31-y period between 1964 and 1995. The results from an analysis of the radionuclide concentrations in the flesh samples indicate the removal rates for the 3 radionuclides are significantly different. 137Cs is removed from the lagoons with an effective half life of 9-12 y. Little 60Co is mobilized to the water column so that it is depleted in both environments, primarily through radioactive decay. The properties of 207Bi are different at Enewetak and Bikini. At Enewetak the radionuclide is lost from the environment with an effective half live of 5.1 y. At Bikini only radioactive decay can account for the rate at which the radionuclide is lost from the lagoon. The difference in the binding properties of the sedimentary materials for 207Bi among the two Atolls is not understood.

Animals↗
PubMed1995

Pregnancy in renal transplant recipients: the Christchurch experience.

AIM: Assess the pregnancies of our female renal transplant recipients and to document long term maternal and fetal outcome. METHODS: Between 7 June 1972 and 31 December 1992 112 females had at least one renal transplant. Sixty-four of these 112 women were in the reproductive age and had a functioning graft. RESULTS: Nine women had 16 pregnancies which resulted in 11 live births and three first trimester abortions. Two unplanned pregnancies were terminated. Mean age at transplantation was 17.2 yr [range 16-22.5 yr] and mean interval from transplant to pregnancy was 6.8 yr [range 1.8-9.0 yr]. Prednisone and azathioprine were used in all patients and cyclosporin in five. For seven of the successful pregnancies plasma creatinine remained < or = 0.10 mmol/L. One of these women developed allograft nephropathy 5 years after delivery and returned to dialysis 9 years later. For the other four successful pregnancies the preconception plasma creatinine was 0.12-0.14 mmol/L. The woman with two successful pregnancies had a halving of glomerular filtration rate during the second pregnancy, but it has remained stable for 15 years; one was poorly compliant with her immunosuppressive regimen and reached endstage renal failure two years after delivery; one developed cyclosporin nephrotoxicity, but 18 months later renal function was stable after a dosage reduction. Ten infants were delivered by caesarean section, four of them urgently. Three babies were preterm and five growth retarded. One died of sudden infant death syndrome at four months. All other infants developed normally. CONCLUSION: There is no contraindication to pregnancy in female transplant recipients who have stable graft function and controlled blood pressure. Management of such pregnancies should be by shared obstetrical/nephrological/paediatric care.

Adolescent↗
PubMed1994

Concentration of 210Po and 210Pb in the diet at the Marshall Islands.

The concentrations of 210Po and 210Pb have been determined in many local foods consumed by societies residing on different atolls in the Marshall Islands. The average daily intake of these two naturally occurring radionuclides from local and imported food is estimated to be 2.18 and 0.36 Bq, respectively. Local foods contribute 87% of the 210Po and 47% of the 210Pb associated with the diet. The items contributing the majority of the activity to the diet are derived from the marine environment and include parts of fish, invertebrates, seabirds and eggs of seabirds. The committed effective dose from ingestion of 210Po and 210Pb is approximately 2 mSv/year (200 mrem/year). This pathway now contributes 83% of the natural background irradiation received by residents in the Marshall Islands. Because the naturally occurring radionuclides are omnipresent in terrestrial and marine foods at all atolls, the annual intake and computed dose can be considered as typical values for individuals with comparable diets and inhabiting other islands in the Pacific.

Adult↗
PubMed1990

[Anesthesia for the low body weight neonates].

58 newborns weighting under 2500 gm were collected, who received surgery in the past five years (1985-1989) in Chang Gung Memorial Hospital, Taipei, and followed up the survivors until April 1990. We classified these 58 cases by physical status that 31 cases (53%) were in ASA II, 26 (45%) in ASA III, 1 (2%) in ASA IV; by body weight that 9 cases (16%) were under 1500 gm, 17 (29%) between 1501 and 2000 gm, 32 (55%) over 2000 gm; by gestational age that 26 cases (45%) were in term pregnancy, 14 (24%) in borderline prematurity, 16 (28%) in moderate prematurity, 2 (3%) in extreme prematurity. All these 58 cases were under endotracheal general anesthesia, the majority of surgery (32 cases) were abdominal procedures. They were all sent to pediatric intensive care unit after operation. The mortality rate was 42% (25 cases), 4 cases of those were dead within the post-operative 24 hours. In this study, the change of temperature during operative procedures was significantly correlative to the neonatal mortality (p less than 0.005).

Anesthesia↗
PubMed1989

Characterization of proteins encoded by the Epstein-Barr virus transactivator gene BMLF1.

Epstein-Barr virus (EBV) encodes a gene product in the BamHI-M leftward reading frame 1 (BMLF1) that functions as a promiscuous transactivator acting upon many other enhancer-promoter combinations. This protein has been studied by producing a polyclonal rabbit antiserum directed against a LacZ-BMLF1 fusion protein that was synthesized in Escherichia coli. Western blotting was employed to demonstrate that this antiserum specifically detected the BMLF1 proteins in E. coli, monkey, mouse, or B cells transfected with this gene, and in EBV-positive B cells chemically induced to produce this protein. In these induced B cells, two major proteins of 50 and 60 kDa and several minor antigens were detected by these antibodies. Transfection of an expression vector containing the BMLF1 coding sequence resulted in the synthesis of only the 50 kDa proteins. These major products were phosphorylated in vivo and were localized to the cell nucleus. Only the larger 60-kDa antigen was specifically induced to be synthesized by a different EBV encoded transactivator, the BZLF1 gene product. Chemical induction of lymphocytes latently infected with EBV resulted in the synthesis of both the 60- and 50-kDa forms of the BMLF1 transactivator. Two major forms of this EBV-encoded transactivator have been detected. The 60-kDa form is presumably derived from the BSLF2-BMLF1 open reading frame while the smaller antigens, 50 kDa size, appear to be made only by the BMLF1 open reading frame. These two forms of the transactivator are differently regulated and the functional significance of this remains to be explored.

Antibodies, Viral↗
PubMed1986

Collagen degradation and synthesis in experimental corneal grafts.

Thirty-two weanling New Zealand white rabbits were labelled repeatedly with [2,3-3-H]-proline for 4 weeks. Four weeks after the end of labelling, 32 rabbits underwent bilateral 6 mm trephinations for donor purposes. One control cornea of each pair was frozen at -70 degrees C. The contralateral corneas were used for autografts, allografts, and xenografts. Grafts were observed from 7-200 days, then retrephined out for determination of loss in total radioactivity in hydroxyproline (specific for collagen), increase in newly synthesized collagen, and net change in collagen mass, by comparing with the matched, ungrafted control corneas. For all three transplant groups there was a small, but significant, decrease early in total radioactivity (loss of original collagen) and a significant increase in new collagen. These data also indicated that the loss of original collagen was replaced by an equivalent or greater increase in new collagen in all transplant groups. Significant relationships between graft clarity and collagen turnover were noted in both the auto- and allograft groups. The degradation of old collagen was significantly greater in the cloudy vs. the clear grafts; however, there was no significant difference in the increase in new collagen between these groups. A progressive loss of original collagen over time was noted in the cloudy autografts, but not the allografts. A trend toward a progressive increase in new collagen was noted over time in both the cloudy auto- and allografts. No relation for these variables to time, however, was noted in the clear grafts.

Animals↗
PubMed1986

Identification and mapping of Epstein-Barr virus early antigens and demonstration of a viral gene activator that functions in trans.

The BamHI M DNA fragment of the Epstein-Barr virus (EBV) genome was inserted in two orientations into a simian virus 40-based expression vector, and the EBV-specific proteins produced in COS-7 monkey cells were examined. In one orientation, termed BamHI-M rightward reading frame 1 (BMRF1), a set of phosphoproteins ranging in size from 47,000 to 54,000 daltons was synthesized. These proteins reacted with monoclonal and polyclonal antisera, defining them as components of the EBV early antigen diffuse set of proteins (EA-D). The BamHI M DNA fragment in the opposite orientation, termed BamHI-M leftward reading frame 1 (BMLF1), directed the synthesis of a nuclear antigen detected by antibodies in serum from a patient with nasopharyngeal carcinoma. The BMLF1 antigen was not detected by monoclonal or polyclonal antibodies directed against the EA-D complex. A series of deletion mutants were constructed in the BamHI M DNA fragment, and the EA-D complex and BMLF1 antigen were mapped to discrete open reading frames in this DNA fragment. A test for several possible functions of these antigens showed that the BMLF1 antigen had the ability to activate or enhance, in trans, the level of expression of a gene under the control of the adenovirus early region 3 promoter or the simian virus 40 early promoter in the absence of its cis-acting enhancer. These experiments demonstrate a new gene function, encoded by EBV, that may be important in the positive regulation of viral or cellular genes.

Antibodies, Monoclonal↗
PubMed1985

Effect of 1,25(OH)2D3 on the relative contributions of skeletal 45Ca and intestinal 40Ca to blood calcium in normal and thyroparathyroidectomized dogs.

The effects of gradually increasing doses of 1,25(OH)2D3 on plasma calcium and 45Ca radioactivity were studied in young dogs that had been extensively prelabelled with 45Ca. The effects of orally and intravenously administered 1,25(OH)2D3 were evaluated in normal and thyroparathyroidectomized dogs fed a normal diet. In normal dogs when 1,25(OH)2D3 increased the plasma calcium within the normal range (2.9-3.1 mmol/L) there was no significant increase in plasma 45Ca. In thyroparathyroidectomized dogs, oral or intravenous 1,25(OH)2D3 increased the low blood calcium to a normal level (1.8-2.9 mmol/L) without significantly increasing plasma 45Ca. In normal and thyroparathyroidectomized dogs, any 1,25(OH)2D3-induced increase in plasma calcium above the normal range was associated with a significant increase in 45Ca, indicating mobilization of bone calcium. Intravenous administration of 1,25(OH)2D3 in the normal or thyroparathyroidectomized dogs had a much larger effect than oral doses in mobilizing bone 45Ca when inducing a similar level of hypercalcemia. The major physiological effect of 1,25(OH)2D3 in the low or normal range of plasma calcium is on intestinal absorption of calcium without a significant effect on mobilizing bone calcium. The pharmacological effect of 1,25(OH)2D3 in vivo is to mobilize bone calcium as well as dietary calcium into blood.

Administration, Oral↗
PubMed1985

Effects of parathyroid hormone on puppies during development of Ca and vitamin D deficiency.

The acute effects of parathyroid extract (PTE) were studied repeatedly in young dogs (prelabeled with 45Ca and [3H]tetracycline) during the development of calcium (Ca) and vitamin D deficiency. Blood Ca and radioactivity changes were monitored sequentially after subcutaneous PTE, injected seven times over 63 days. In control dogs, all sequential responses to acute PTE challenges were constant in both magnitude of increase and time at which maximum response occurred over the entire experiment. Under chronic Ca and D deficiency, plasma 25-hydroxyvitamin D in experimental dogs decreased continuously to very low levels at 63 days, whereas 1,25-dihydroxyvitamin D initially increased to a maximum at 32 days and thereafter decreased. In response to an acute challenge of PTE, dogs on the deficient diet for 3 and 10 days showed a greater response of blood Ca and 45Ca than the controls but subsequently showed a smaller response than controls after 49 and 63 days on the deficient diet. Compared with control dogs, the time of maximal response of blood Ca and 45Ca to PTE occurred much earlier in dogs that were on the deficient diet for 35-63 days. The blood [3H]tetracycline response (index of bone resorption) to exogenous PTE in the deficient dogs, however, was constant and similar to that of the control dogs during the entire period. The data suggest that the bone resorption response to PTE was normal in Ca- and D-deficient puppies with hypocalcemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Circadian variations in contributions of bone and intestine to plasma calcium in dogs.

Young euparathyroid dogs, prelabeled with radiocalcium and fed a normal-calcium diet exhibited circadian variations in the amount of bone calcium contributed to the plasma calcium pool, as evaluated by changes in plasma calcium-45 radioactivity. When these dogs were fed a low-calcium diet or fasted, the contribution of bone calcium to plasma calcium rose to the point where bone constituted nearly the sole source of plasma calcium, and plasma calcium-45 no longer varied. In thyroparathyroidectomized (TPTX) dogs fed a normal diet, the fraction of plasma calcium due to bone contribution was reduced and plasma calcium-45 did not vary. When dietary calcium in TPTX dogs was increased by supplementation with calcium lactate pills, total plasma calcium rose, but the contribution of bone calcium to the plasma calcium pool remained unchanged. Thus the ability of normal young dogs to modulate bone calcium mobilization in response to dietary calcium intake appears to be hormonally regulated in a circadian manner.

Animals↗