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Biomedical subjects

C Lim

Publications and source records attributed to C Lim.

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

Effects of glucocorticoids on the growth of human fibrosarcoma cell line HT-1080.

The human fibrosarcoma cell line HT-1080 exhibits rapid growth following s.c. inoculation in 4-6-week-old male athymic mice. Cytosols from tumors carried in athymic mice bind glucocorticoid (Kd, 1.8 +/- 0.48 X 10(-8) M; Bmax, 240.5 +/- 35.3 fmol/mg cytosol protein, mean +/- SEM). Receptor sediments primarily in the 8-9S region on 5-20% sucrose gradients and is specific for the glucocorticoids. HT-1080 growth in vitro (as measured by cell count) was inhibited over a range of 10(-6)-10(-8) M after 7 days of incubation with dexamethasone and triamcinolone acetonide. Progesterone, estradiol, and dihydrotestosterone had no effect on HT-1080 growth in vitro. Preincubation with a 100-fold excess of progesterone reversed the growth inhibition observed with triamcinolone acetonide but not dexamethasone acetate. HT-1080 tumor cell growth responded biphasically to dexamethasone in vivo. Athymic mice given s.c. injections every other day with 5 or 25 micrograms dexamethasone showed an increase in tumor size inversely proportional to dose. In contrast, 200 micrograms of dexamethasone significantly inhibited tumor growth. Adrenalectomy did not significantly alter HT-1080 growth or glucocorticoid binding to tumor cytosols (Kd, 3.4 X 10(-8) +/- 1.1, Bmax, 236.9 +/- 9.9 fmol/mg cytosol protein, mean +/- SEM) although tumor incidence was decreased in sham adrenalectomized mice. Glucocorticoid binding in tumors grown in vivo was decreased by increasing amounts of dexamethasone. High pharmacological doses of glucocorticoids inhibit the growth of human fibrosarcomas in vivo and in vitro.

Adrenalectomy↗
PubMed1985

Maternal-child hepatitis B virus transmission in Singapore.

A study of maternal-infant transmission of hepatitis B virus (HBV) was conducted in Singapore between June 1980 and June 1982. HBsAg carrier rate was highest among Chinese (6.2%) followed by Malay (2.3%) and Indian (0.6%) mothers. The presence of HBeAg in maternal sera correlated well with high titre HBsAg (p = 7.34 X 10(-5)). Overall HBV transmission occurred in 27/56 (48.2%) infants from carrier mothers. The majority of the transmission was perinatal. There was a very strong correlation between transmission and HBeAg status of the mother (p = 1.85 X 10(-9); odds ratio = 68.44) and to a lesser extent with high titre HBsAg (p = 0.002; odds ratio = 6.38). A strong negative correlation was seen between transmission and anti-HBeAg (p = 8.19 X 10(-7); odds ratio = 0.04). At one year 19 (70.4%) infants were still HBsAg positive while seven (25.9%) lost the antigenemia and acquired anti-HBsAg and one developed HBsAg after one year. It could be calculated that perinatal HBV transmission contributed about 18% to the total pool of HBsAg positive infants of one year of age.

Carrier State↗
PubMed1985

The association between idiopathic hemolytic uremic syndrome and infection by verotoxin-producing Escherichia coli.

Forty pediatric patients with idiopathic hemolytic uremic syndrome (HUS) were investigated for evidence of infection by Verotoxin-producing Escherichia coli (VTEC). Fecal VTEC (belonging to at least six different O serogroups including O26, O111, O113, O121, O145, and O157) or specifically neutralizable free-fecal Verotoxin (VT) or both were detected in 24 (60%) patients but were not detected in 40 matched controls. Ten of 15 of the former developed fourfold or greater rises in VT-neutralizing antibody titers, as did six other patients who were negative for both fecal VTEC and VT. A total of 30 (75%) patients had evidence of VTEC infection by one or more criteria. We concluded that a significant association exists between idiopathic HUS and infection by VTEC. The detection of free-fecal VT was the most important procedure for the early diagnosis of this infection because, in our study, VTEC were never isolated in the absence of fecal VT, whereas fecal VT was often present even when VTEC were undetectable.

Acute Disease↗
PubMed1985

Sensitive method for detecting low numbers of verotoxin-producing Escherichia coli in mixed cultures by use of colony sweeps and polymyxin extraction of verotoxin.

High titers of Verotoxin (VT) were released from cell pellets of VT-producing Escherichia coli (VTEC; corresponding to E. coli strains producing "high" levels of Shiga-like toxin) after incubation in polymyxin B (0.1 mg/ml) for 30 min at 37 degrees C. Maximal titers of polymyxin-releasable VT occurred in cells obtained from 5-h Penassay broth cultures and were up to eightfold higher than the peak culture supernatant VT titers which occurred in 8-h cultures. Polymyxin-releasable cell extracts of 5-h broth cultures inoculated with mixtures of VT-positive (VT+) and VT-negative strains had easily detectable VT titers when the proportion of VT+ cells in the mixture was about 1.0%, but culture supernatants were negative for VT even when this proportion was 20%. The results were the same whether the initial inoculum consisted of broth culture mixtures of VT+ and VT-negative strains or colony sweeps (loopfuls of confluent bacterial growth) taken from solid plate media previously inoculated with the broth mixtures. In a clinical study, 80 stool cultures from patients with hemolytic uremic syndrome and family contacts with diarrhea were tested for free fecal VT, VT in polymyxin extracts of colony sweeps (VT/PECS), and VTEC (examination of 20 separate E. coli colonies from primary media for VT production). Of the 80 samples, 40 were positive for at least one of these three tests; all 40 were positive for free fecal VT, and 20 of these were positive for VT/PECS. VTEC (as few as 1 colony out of 20) were only isolated from 14 of the 20 cultures that were positive for VT/PECS. In six cases, the VT/PECS was positive even when none of 20 colonies tested were VT+, suggesting that the procedure was able to detect a proportion of VTEC that was less than one in 20(5%). We conclude that the VT/PECS method is highly sensitive for detecting low concentrations of VTEC in stools and provides a rapid method for screening out stools that are negative for VTEC. The technique should also be of value in epidemiological studies for detecting low numbers of VTEC in animal feces, foods, and environmental samples.

Bacterial Toxins↗
PubMed1983

Sporadic cases of haemolytic-uraemic syndrome associated with faecal cytotoxin and cytotoxin-producing Escherichia coli in stools.

A cytotoxin active on Vero cells, less active on hela cells, and inactive on WI38 cells (Vero toxin [VT]) was detected in stool isolates of Escherichia coli from 8 of 15 sporadic cases of haemolytic uraemic syndrome (HUS). Stools from 5 of these 8 patients were examined for faecal VT activity, and all were positive. Of the 7 of 15 patients who did not have VT+ E. coli, 2 were positive for faecal VT, and a third (patient K) had strong serological evidence of VT+ E. coli infection. 2 HUS patients, including patient F, had siblings with uncomplicated diarrhoea who had both VT+ E. coli in the stools and faecal VT activity. Thus 11 of 15 (73%) of the HUS cases had evidence of infection by VT+ E. coli, suggesting that there was an association between these organisms and these cases of HUS. The clustering of 2 HUS patients and their siblings with VT+ E. coli accords with this suggestion, as do the rising titres of VT-neutralising antibody in 2 HUS patients.

Antibodies↗
PubMed1982

[Study of cellular immunity using Rebuck's skin-window (author's transl)].

Value of a modification of Rebuck's skin-window in cellular immunity studies. The mononuclear/polynuclear ratio is determined at given time-intervals. The increase in the number of macrophages as well as their kinetics can be pictured on a diagram, comparatively to the corresponding results in controls. This test appears to provide a means of assessing the activity of a malignant disorder.

Humans↗
PubMed1978

Pathology of the vitamin C deficiency syndrome in channel catfish (Ictalurus punctatus).

Channel catfish fingerlings fed purified diets devoid of vitamin C showed reduced growth rate, deformed spinal columns, external and internal hemorrhages, erosion of fins, dark skin color and reduced bone collagen content after 8 to 12 weeks, whereas fish fed a diet containing 30 mg/kg of vitamin C had none of these anomalies after 22 weeks. A dietary level of 30 mg of vitamin C per kg was insufficient to prevent distortion of gill filament cartilage, although 60 mg of vitamin C per kg was sufficient. Vertebral collagen percentages of 25 or below and liver ascorbic acid levels of 30 microgram/g or below appeared to be indicative of vitamin C deficiency in channel catfish fingerlings. Epidermis and dermis were almost completely healed and extensive collagen fiber formation had commenced in the somatic muscle, in experimentally inflicted wounds after 10 days in fish fed the vitamin C-free diet. Skin and muscle at the wound site were almost regenerated to normal after 10 days in fish fed 60 mg of vitamin C per kg of diet.

Animals↗
PubMedDate not supplied

Comparison of central venous catheterization sites in infants.

This study aimed to compare the rates of success and complications between different sites of central venous catheterization in infants. A total of 272 infants were randomized to four groups: right subclavian group (G-RSCV), right internal jugular group (G-RIJV), left subclavian group (G-LSCV) and left internal jugular vein group (G-LIJV). In 77.2% of the patients, we successfully introduced a catheter at the first attempt. The rate of successful catheter placement was highest in the and LSCV 55.9%). With regard to complications, the rate of arterial puncture, guide wire advancement failure and malpositioning of the catheter were all significantly more frequent during SCV catheterization (SCV versus IJV: 10.1% versus 2.1%, 12.4% versus 0% and 13.4% versus 0.6%, respectively). Our results imply that IJV, especially RIJV, should be the first choice for central venous catheterization in infants.

Catheterization, Central Venous↗