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C H Lim

Publications and source records attributed to C H Lim.

At least 37 records · Page 2Linked to original sources
PubMed1997

Early detection of optic nerve-evoked response in the superior colliculus of the neonatal rat.

Optic nerve-evoked responses were measured in the superior colliculus (SC) of neonatal rats in vivo from postnatal day (P) 0 to P11. At P1, a biphasic response was recorded in superficial layers and the amplitude diminished as the electrode penetrated into the deeper layers of the SC. By P2, a similar response, with a fast positive-going potential followed by a more prolonged negative potential was observed at the surface. The polarity of the response reversed as the electrode was moved into the deeper laminae of the SC. Such a reversal in the polarity of optic nerve-evoked responses resembled those observed in more mature preparations. Using current source density analysis, a single pair of source-sink could be identified following optic nerve stimulation at P2, and this changed to a more complex pattern by P11. Our results suggest that synaptic transmission in the retinocollicular pathway of the rat is functional as early as P2.

Animals↗
PubMed1997

Effects of 2-bromopropane on the female reproductive function in Sprague-Dawley rats.

2-Bromopropane (2BP) has been implicated to be the reason for the mass intoxication of workers at an electronic company in Korea. A case series study indicated that 2BP was the possible causative chemical for reproductive toxicity, causing severe anemia accompanied by amenorrhea among female workers, and azoospermia or oligospermia among male workers. To clarify the effect of 2BP on the female reproductive function, repeated doses of 2BP were tested on female Sprague-Dawley rats for 21 days. Ten rats were assigned to each treatment group. The rats were maintained in a 12 hr: 12 hr light-dark cycle and vaginal smears were monitored daily for 3 cycles. After the rats had completed 3 estrous cycles, vehicle control olive oil, 300 mg, 600 mg, and 900 mg/kg of 2BP were injected into intraperitoneum for 14 days. The female rats were then mated with male rats on a 1:1 ratio basis. The treatment continued for an additional 7 days. Rats treated with 2BP experienced a significant decrease in body weight gain depending on the dose of 2BP. The estrous cycles of the rats continued at a normal duration of time before the initiation of treatment, showing 4.32 days for the control group, 4.79 days for the low dose, 4.63 days for the middle dose, and 4.75 days of estrous cycle for the high dose group. 2BP treatment, however, induced a significant delay of the estrous cycle in the high dose treated group, showing 11.1 +/- 3.82 days of the estrous cycle. 2BP decreased the fertility and tended to decrease in the number of pups born, depending on the dose. A 900 mg/kg treatment of 2BP decreased ovarian weight, but 2BP did not affect the length of gestation. Our results indicated that 2BP seemed to be the causative agent for amenorrhea observed in female workers.

Animals↗
PubMed1997

Reproductive toxicity of 2-bromopropane in Sprague Dawley rats.

OBJECTIVES: In an effort to clarify the mass intoxication of workers at an electronic company in Korea, the possible causative chemical for reproductive toxicity, 2-bromopropane (2BP), was investigated. METHODS: 2BP was tested through the use of repeated dose experiments among male Sprague Dawley rats. Ten rats were assigned to each treatment group. Vehicle control olive oil and 2BP concentrations of 125 mg/kg, 250 mg/kg, and 500 mg/kg were injected into the intraperitoneum on 28 consecutive days. RESULTS: The rats showed significant decreases in body weight depending on the 2BP dose. The right and left testes showed typical weight loss depending on the dose of 2BP. The red blood cells, hemoglobin, and hematocrit showed some degree of decline with the high dose. The amount of hemoglobin, the mean platelet volume, the number of white blood cells, and the number of lymphocytes decreased significantly with the high dose, while the number of granulocytes and monocytes had a tendency to decrease depending on the dose of 2BP. The histopathology of the testes treated with the middle and high 2BP dose showed a typical patch appearance with severely depleted atrophic tubules, exhibiting germ cell necrosis of spermatogonia and spermatocytes in the seminiferous tubules. Leydig cell hyperplasia or hypertrophy in the interstitial tissue was also noticeable. The epididymis showed some degree of atrophy with vacuolization of the epididymal epithelium. CONCLUSIONS: The testes are the main target organs tested for 2BP toxicity. 2BP also affect the hematopoietic system and thus induces leukopenia and normocytic anemia. Besides the reproductive organs and the hematopoietic system, no significant toxicity has been found.

Animals↗
PubMed1995

The recovery of heat-stressed Escherichia coli in lake water microcosms.

Escherichia coli was heat stressed at 55 degrees, 60 degrees or 65 degrees C in sterile flasks of lake water. After 6 h at these temperatures the viable count on nutrient agar had dropped below the limits of detection (1 colony in 100 ml). The flasks were transferred to a 15 degrees C incubator and left for 7 d. Recovery of the stressed E. coli was shown to occur within 48 h at this temperature. Recovery also occurred in microcosms amended with 5% (v/v) synthetic sewage. The stressed E. coli multiplied in the amended but not in the unamended microcosms.

Ecosystem↗
PubMed1994

Isoelectric focusing and selectivity index in IgA nephrotic syndrome.

Proteinuria in 13 patients with IgA nephritis with nephrotic syndrome (IgANS) was analysed by isoelectric focusing (IEF) and compared with 12 patients with minimal change nephrotic syndrome (MCNS) (n = 8) or focal global sclerosis nephrotic syndrome (FGS) (n = 4) to determine the pattern of proteinuria on IEF and to assess the value of IEF and protein selectivity index (SI) as predictors of response to therapy with predisolone or cyclophosphamide. Steroid/cyclophosphamide responsive patients with IgANS had SC:UA (cationic serum albumin with anionic urine albumin) or SA:UC (anionic serum albumin with cationic urine albumin) IEF patterns and steroid/cyclophosphamide unresponsive patients with IgANS had an SC:UC (cationic serum albumin with cationic urine albumin) IEF pattern. The majority of patients with MCNS or FGS who had an SA:UC IEF pattern were steroid responsive. SI was a better predictor of steroid/cyclophosphamide responsiveness in patients with IgANS (r = 0.78, p < 0.002 compared to IEF, r = 0.64, p < 0.02).

Adolescent↗
PubMed1993

Continuous ambulatory peritoneal dialysis in type II diabetics.

Forty-two Type II diabetic patients with end stage renal failure who had never previously received dialysis treatment were treated with continuous ambulatory peritoneal dialysis (CAPD) for a period of two to 48 months (average 16.8 months) with a total experience of 640 patient-months. Of the 42 patients, 29 (69%) were male and 13 (31%) were female. The mean duration of diabetes before dialysis was 12 years. Eleven patients (40%) were on dietary control alone, seven patients (24%) on oral hypoglycaemic control and ten patients (36%) on insulin treatment. Blood glucose control between these groups did not differ significantly. There was a significant gain in dry weight from a mean of 60.3 kg prior to dialysis to 74 kg two years after dialysis. There was no significant improvement in the haemoglobin level. Blood triglyceride levels increased from 214 +/- 63 mgm/dl to 283 mgm +/- 156 mgm/dl with an insignificant reduction in the cholesterol level. Serum calcium levels increased significantly from 8.0 +/- 1.3 to 9.1 +/- 1.0 mgm/dl in 12 months (p < 0.05). Serum alkaline phosphatase level remained stable. Blood pressure was stable throughout the dialysis period. Adequacy of dialysis clearance was shown by the mean value of serum urea 115 +/- 40 mgm/dl, serum creatinine 10.6 +/- 2.7 mgm/dl and serum phosphate 4.65 +/- 1.6 mgm/dl after two years on CAPD. No peritoneal membrane failure was reported.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The role of glutathione in the acute nephrotoxicity of sodium dichromate.

Ascorbate treatment 30 min prior to sodium dichromate (20 or 30 mg/kg, s.c.) shows higher potency than that of glutathione (GSH) in protecting against both the metabolic disturbance and nephrotoxicity induced by dichromate. However, ascorbate treatment after 2 h of dichromate intoxication had no effect on dichromate-induced blood urea nitrogen (BUN) elevation 3 days after intoxication. In contrast, dichromate-induced glucosuria, which reached maximum levels at 3 days after treatment, was significantly decreased by GSH or N-acetyl cysteine (NAC) treatment, even if its administration was after 24 h of dichromate intoxication. Pretreatment with GSH depletors such as diethyl maleate (DEM) and buthionine sulfoximine (BSO) had no effect on dichromate-induced nephrotoxicity. GSH levels in the liver and kidney were not affected at 3 h after dichromate treatment. However, dichromate significantly increased tissue GSH levels with a marked increase in liver per kidney GSH ratio at 24 h after treatment, if food was withheld subsequent to dichromate treatment, indicating that GSH biosynthesis resulted from the accelerated protein breakdown. These results suggest that GSH-mediated dichromate reduction is not a kinetically favorable pathway in vivo; however, GSH plays an important role in protection against dichromate-induced nephrotoxicity. In addition, the cellular metabolism of dichromate in the early period after treatment is important in the pathogenesis of its nephrotoxicity.

Animals↗
PubMed1992

Cytomegalovirus infection in renal transplant patients with hepatitis B--case report.

Cytomegalovirus (CMV) infection in Hepatitis B carrier renal transplant patients who are immunosuppressed can be easily overlooked especially in those presenting with jaundice and liver failure. Recognising hepatitis due to CMV in renal transplant patients who are also hepatitis B carriers is important therapeutically as measures for the treatment and prevention of CMV infection are already available. This is especially so as Hepatitis B has a moderately high prevalence in this part of the world. We describe our clinical experience of cytomegalovirus infection in two renal transplant patients who are also asymptomatic hepatitis B carriers.

Adult↗
PubMed1992

The impact of HLA match transfusions and presensitization on renal transplantation in the cyclosporine era.

The successful engraftment of a renal transplant is dependent on multiple factors, immunological factors being of major importance. Specifically, histocompatibility, lymphocytotoxic antibodies and pretransplant blood transfusions have been shown to play a major role in determining graft outcome in renal transplant recipients receiving Azathioprine-Prednisolone immunosuppression. The impact of the immunosuppressive drug, Cyclosporine on graft outcome in relation to established risk factors were examined among 116 cadaveric and 34 living related renal allograft recipients from our center. Histoincompatibility and pretransplant blood transfusions did not significantly affect graft survival among cadaveric transplant recipients. Similarly, graft survival was not significantly different between two haplotype-matched and less well-matched living-related graft recipients (75% versus 96.5% respectively). On the other hand, lymphocytotoxic antibodies remained a major risk factor for immunologically mediated graft loss among cadaveric graft recipients (48.0% versus 92.2% four year graft survival among those with and without antibodies respectively). These results suggest that Cyclosporine has abrogated some immunological risk factors in renal transplantation.

Adult↗
PubMed1991

Influence of extended practice on programming time, movement time, and transfer in simple target-striking responses.

Two experiments describe the effects of extended practice on the development of motor control programs for simple target-striking responses. In Experiment 1,400 right-hand trials of simple one-target and two-target striking tasks were performed. In Experiment 2,600 practice trials were given. Overall reaction time (RT) was faster for the one-target condition in both experiments, supporting a response complexity effect. Movement time (MT) for both conditions improved linearly with practice, suggesting that development of the motor control programs was still occurring. Subjects then transferred to a three-target condition for 50 trials, performing the transfer task with the right hand in Experiment 1, and with right and left hands in Experiment 2. Transfer to the three-target conditions produced execution errors in the form of failure to contact the second target and repetitive tapping on the third target. These results suggest that extensive practice may serve to firmly entrench a response sequence, making it difficult to implement a similar, but unique, motor control program. An interpretation in terms of automaticity and enhanced priming of behavioral and neural pathways is offered to account for these results.

Journal Article↗
PubMed1991

Pharmacokinetics and nephrotoxicity of cyclosporine.

Cyclosporine (CsA) is a potent immunosuppressive agent which has dramatically improved graft and patient survivals in clinical solid organ transplantation. However, CsA nephrotoxicity (NTX) is the most frequent and serious side effect of CsA therapy and occurs in a significant proportion of patients. The clinical presentation of NTX is that of reduced creatinine clearance, elevation of serum creatinine and a disproportionate rise in blood urea. The clinical picture occurs as three syndromes, namely acute, subacute and chronic CsA NTX. Regardless of the clinical syndrome, the pathoaetiology of NTX is related to decline in renal blood flow and increase in renal vascular resistance probably due to CsA induced changes in renal haemodynamics. Unfortunately, the dose that yields an optimal therapeutic index, namely maximal efficacy with minimal toxicity has yet to be defined. Optimal dosing is confounded by not only inter and intraindividual variabilities in drug absorption, distribution and metabolism, but also by the lack of a clear relationship between drug efficacy and trough CsA level monitoring. This paper describes the pharmacokinetics and nephrotoxicity of CsA and evaluates various strategies to overcome this toxicity.

Absorption↗
PubMed1991

Maintenance haemodialysis in Singapore.

The chronic haemodialysis programme of the Singapore General Hospital started in 1968 as a hospital-based fully nurse-assisted programme. This has since expanded to include Self Dialysis and Home Dialysis programmes. Data of 425 patients who entered the dialysis programmes was analysed retrospectively. The major cause of end stage renal failure was chronic glomerulonephritis (52%). Almost half of the patients in the haemodialysis programme were patients on self-dialysis (49%). There were 157 withdrawals and 116 deaths. Survival has improved tremendously with the use of treated water for dialysis from 1981. The 5 year survival in an earlier group of patients dialysed with untreated water was 48% compared with 81% in a late group dialysed with treated water (p less than 0.001). The pattern of complications has also changed with a lower incidence of dialysis osteomalacia, hypertension, hepatitis and eradication of dialysis dementia.

Acute Kidney Injury↗
PubMed1991

Pattern of proteinuria in IgA nephritis by SDS-PAGE: clinical significance.

Of sixty patients with IgA nephritis, none had CRF at first examination, 13 developed CRF with creatinine above 1.6 mg/dl within 6 years. Among these patients who had analysis of proteinuria by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), 31 patients had middle molecular weight (MMW) proteinuria alone (pattern 1), 10 had MMW and Low MW (LMW) or tubular proteinuria (pattern 2), 10 had high MW (HMW) and MMW proteinuria (Pattern 3) and 9 had HMW, MMW and LMW proteinuria (Pattern 4). At the end of a follow up period of 6 years (1983-1989) patients with mixed proteinuria had a higher incidence of chronic renal failure (CRF), 11/29 (38%) compared to those with pattern 1 proteinuria, 2/31 (6%) (chi 2 = 8.7, p less than 0.005). Based on the glomerular selectivity index (GSI), 19 patients had nonselective proteinuria but they did not have a higher incidence of CRF. By the selectivity index (SI), 18 patients had nonselective proteinuria and they showed a significantly higher incidence of CRF. Compared to the 41 patients who did not have LMW proteinuria, 19 patients with LMW proteinuria had more severe proteinuria. After a follow-up period of 6 years, patients with LMW proteinuria had a higher incidence of CRF (10% versus 47%, p less than 0.001). The presence of LMW proteinuria indicates a less favourable outcome and the pattern of proteinuria as assessed by the SDS-PAGE appears to be a better prognostic index in IgA nephritis than the SI and the GSI.

Adult↗