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Biomedical subjects

C K Li

Publications and source records attributed to C K Li.

At least 109 records · Page 6Linked to original sources

Treatment of hemoglobin Bart's hydrops with bone marrow transplantation.

A 21-month-old girl with hemoglobin Bart's hydrops received bone marrow transplantation (BMT) from a matched sibling. No major BMT-related complications developed. Hemoglobin levels remained greater than 10 gm/dl for 20 months without blood transfusion support despite the presence of residual host hemopoietic cells from 2 months after BMT. We suggest consideration of this therapeutic option for surviving patients.

Bone Marrow Transplantation↗

A prospective randomized trial of suture of the patellar tendon defect after harvesting.

In a rabbit model, we studied the long-term biomechanical and biochemical effects of leaving the patellar tendon unsutured, or closing the defect with absorbable sutures, after harvesting one third. Using a prospective randomized design, after harvest of its central third, the patellar tendon was either sutured side to side with absorbable sutures, or left unsutured in 112 skeletally mature rabbits. The rabbits were killed at 2 and 6 weeks, and 6 and 9 months postoperatively. After an initial increase in both groups (.001 < P < .019), water content decreased from 2 weeks to 9 months after the operation (.02 < P < .0045), and remained significantly greater than in the control contralateral limb at all times (.00 1 < P < .003). Collagen content showed no significant differences between the two experimental groups. The operated tendons always showed a decreased collagen content at all time periods (.012 < P < .049). Failure load, ultimate stress, stiffness, and energy absorbed before failure tended to gradually return to normal over 9 months after a significant initial drop. There were no significant differences between the two experimental groups in failure load, ultimate stress stiffness, and energy absorbed before failure. At 9 months, the operated patellar tendon was significantly thicker (.0016 < P < .03) and had a greater cross-sectional area (.01 < P < .03) than the contralateral control regardless of whether it had been sutured or left open. After removal of the central third, closing the tendon gap with absorbable sutures or leaving it open makes little difference on the biomechanical and biochemical properties of the remaining patellar tendon.

Animals↗

Flow cytometric assessment of oxidant stress in age-fractionated thalassaemic trait erythrocytes and its relationship to in vitro growth of Plasmodium falciparum.

The role of oxidant stress in mediating the protection against malaria in thalassaemic red blood cells (RBC) has been hypothesized. In this study we have assessed the relationship between oxidant stress, red cell age and malarial parasite activity in thalassaemic RBC. Using a flow cytometric method to assess lipid peroxidation, we have shown that the age-related increase in sensitivity to oxidative stress previously demonstrated in normal RBC also occurs in thalassaemic RBC. Invasion and growth of Plasmodium falciparum was also shown to deteriorate with increasing RBC age. This effect was more pronounced in thalassaemic RBC with associated schizont maturation arrest and abnormal parasite morphology. In addition, there was a slight but consistent inverse correlation between sensitivity to oxidant stress and parasite activity (R = -0.43; P = 0.03 for normal RBC and R = -0.42; P = 0.01 for thalassaemic RBC). Our findings indicate an association between red cell age, oxidant stress and P. falciparum growth, providing further support for the role of oxidant stress in mediating the protective effect against malaria in thalassaemic RBC.

Animals↗

Isolated testicular relapse after bone marrow transplant with total body irradiation and testicular boost in acute lymphoblastic leukemia.

A 7-year-old boy with Ph+ ALL received an allogeneic BMT in second remission. Conditioning included cyclophosphamide 60 mg/kg for 2 days, TBI 2 Gy twice daily for 3 days (12 Gy) and a single testicular boost of 4 Gy. He remained in hematological remission after BMT but developed isolated testicular relapse at 17 months. He underwent orchiectomy of the affected testis, 24 Gy testicular radiotherapy and systemic chemotherapy. He remains in remission 24 months after the testicular relapse. This is the first report of isolated testicular relapse which received a testicular irradiation boost included in the conditioning.

Bone Marrow Transplantation↗

Magnetic resonance imaging evaluation of the pituitary gland and hypothalamus in thalassaemic children with elevated serum ferritin levels.

OBJECTIVE: Despite modern treatment with hypertransfusion and chelation therapy, growth retardation continues to be observed in a significant proportion of thalassaemic children. The underlying reason remains unclear, but hypothalamic-pituitary axis disorder has been implicated. We aimed to assess iron overloading in the hypothalamus and pituitary gland in thalassaemic children with elevated serum ferritin, with and without growth retardation. METHODOLOGY: Twelve thalassaemic children on hypertransfusion and chelation therapy with high serum ferritin were investigated with magnetic resonance imaging (MRI). Five children, all over 10 years of age, had growth retardation. Gradient recalled echo sequence was used to highlight any susceptibility effect that could be due to iron in the hypothalamus or pituitary gland. RESULT: There was no evidence of abnormal hypointense signal in the hypothalamus or pituitary gland in the patients studied, regardless of the presence of growth retardation. CONCLUSION: There was no apparent characteristic MRI appearances of iron deposition in the hypothalamus or pituitary gland in thalassaemic children with high serum ferritin.

Adolescent↗

A Chinese adolescent girl with Fechtner-like syndrome.

We describe a 15-y-old girl with Fechtner-like syndrome, who is the first Chinese reported to have this rare syndrome. She presented with left homonymous hemianopia and neuroimaging revealed haemorrhage in both parietal and occipital lobes. Peripheral blood smear showed macrothrombocytopenia and intracytoplasmic inclusion bodies inside leucocytes. Thrombocytopenia and proteinuria responded to intravenous immunoglobulin and pulsed methylprednisolone. This case illustrates that life-threatening haemorrhage can occur in patients with Fechtner syndrome. Although there was no effective treatment reported in the literature, high dose steroid and immunoglobulin seemed to be useful in our patient. Our patient also had nephritic-nephrotic syndrome with renal insufficiency, which is unusual in adolescent female patients.

Adolescent↗

Is homozygous alpha-thalassaemia a lethal condition in the 1990s?

Two cases of homozygous alpha-thalassaemia who received active treatment in accordance with parental wishes are reported. One infant survived and the other, although successfully weaned off mechanical respiratory support, unexpectedly developed portal vein thrombosis and died. Homozygous alpha-thalassaemia, a condition previously considered to be universally fatal, and an indication for therapeutic abortion, is now potentially curable with advances in diagnostic technology and treatment. However, active management of these cases raises serious ethical questions and has major financial implications on the health-care system. Invasive prenatal and intensive postnatal interventions should remain experimental and cannot be recommended as routine clinical practice until the questions of long-term neurodevelopmental outcome, and the morbidity and mortality associated with bone-marrow transplantation have been fully addressed. As a result of advances in information technology, more and more parents of affected foetuses are likely to request active treatment.

Fatal Outcome↗

Production of proinflammatory cytokines and inflammatory mediators in human intestinal epithelial cells after invasion by Trichinella spiralis.

Epithelial cells are the first point of host contact for invasive intestinal pathogens and may initiate mucosal inflammatory responses via production of proinflammatory cytokines and mediators. The aim of the present study was to investigate in vitro the initial invasion of a parasitic nematode (Trichinella spiralis), to measure the early production of specific epithelial cytokines and inflammatory mediators after invasion, and to compare these responses with those to invasive bacteria. Monolayers of human colonic epithelial cell lines (HT29, T84, and Caco-2) were infected by T. spiralis or Listeria monocytogenes. Bile-activated infective larvae of T. spiralis invaded and migrated into the epithelial cell monolayers, leaving trails of dead cells. Transmission electron microscopy studies of damaged cells along the trail showed a progressive increase in size, disruption of cell membranes, loss or dilution of cytoplasmic proteins, and swelling of mitochondria and nuclei. However, no nuclear fragmentation was observed. With reverse transcription-PCR and an enzyme-linked oligonucleotide chemiluminescent assay, mRNA transcripts of interleukin-1beta (IL-1beta), IL-8, and epithelial neutrophil-activating peptide 78 were shown to increase in epithelial cells invaded by T. spiralis or L. monocytogenes, but only L. monocytogenes elicited increased inducible nitric oxide synthase (iNOS) mRNA. No increase in tumor necrosis factor alpha or transforming growth factor beta mRNA was seen after T. spiralis invasion. Increased levels of IL-8 were also released from the basolateral surfaces of infected monolayers as detected by sandwich enzyme-linked immunosorbent assay. Induction and secretion of proinflammatory cytokines in epithelial cells after nematode or bacterial invasion may initiate the acute inflammatory response of the small intestine. The upregulation of iNOS in bacterial infections may contribute to mucosal defense and may also be associated with subsequent cell death, whereas different mechanisms appear to operate after nematode invasion.

Animals↗

Ethnic differences in the hypertensive heart and 24-hour blood pressure profile.

Black hypertensive persons have been observed to have a greater degree of left ventricular hypertrophy than white hypertensives. However, previous studies have matched groups for blood pressure (BP) measured in the clinic, and it has been demonstrated that black hypertensives have an attenuated nocturnal BP dip. Clinic BPs may thus underestimate mean 24-hour BP in this group. To investigate whether the differences in left ventricular hypertrophy can be accounted for by the greater mean 24-hour BP in black hypertensives, 92 previously untreated hypertensives were studied with 24-hour ambulatory BP monitoring and echocardiography. The 46 black hypertensives (24 men and 22 women) were matched with the 46 white hypertensives for age, gender, and mean 24-hour BP. Despite similar mean 24-hour BPs (blacks, 142/93 mm Hg; whites, 145/92 mm Hg; P=.53/.66), the black group had a smaller mean nocturnal dip than the white group (blacks, 8/8 mm Hg; whites, 16/13 mm Hg; P<.01). In addition, mean left ventricular mass index (LVMI) was greater (blacks, 130 g/m2; whites, 107 g/m2; P<.001). Mean 24-hour systolic BP was significantly related to LVMI in both groups (blacks, r=.45, P<.01; whites, r=.56, P<.01). However, systolic BP dip correlated inversely with LVMI only in the black group (blacks, r=-.30, P<.04; whites, r=.05, P=.76). In a multiple regression model, LVMI was independently related to both mean daytime BP and mean nocturnal BP dip in black subjects but only to mean daytime BP in white subjects. In conclusion, the increased left ventricular hypertrophy observed in black hypertensives compared with white hypertensives is not accounted for by differences in mean 24-hour BP. However, LVMI in black hypertensives appears to be more dependent on nocturnal BP than that in white hypertensives; this, coupled with the attenuated BP dip in black hypertensives, suggests that the BP profile rather than 24-hour BP may be important in determining the differences in left ventricular hypertrophy.

Adult↗

A technique for enhancing union of allograft to host bone.

The aim of limb-salvage surgery in malignant bone tumours in children is to restore function and eradicate local disease with as little morbidity as possible. Allografts are associated with a high rate of complications, particularly malunion at the allograft-host junction. We describe a simple technique which enhances union of allograft to host bone taking advantage of the discrepancy in size between the adult allograft and the child's bone. This involves lifting a flap of periosteum before resection from the host bone, which is then telescoped into the allograft medullary canal, which may require internal burring or splitting, for a distance of 1.5 to 2 cm and covering the bone junction with the periosteal flap. This is more stable than conventional end-to-end opposition. For each centimetre of telescoping the surface area available for bony union is increased more than three times. The periosteal flap also augments union. Additional surface fixation with a plate and screws is not necessary. We have used this technique in nine children, in eight of whom there was complete union at a mean of 16 weeks. Delayed union, associated with generalised limb osteoporosis, occurred in one. Early mobilisation, with weight-bearing by three weeks, was possible. There was only one fracture of the allograft.

Bone Neoplasms↗

In utero exchange transfusion in homozygous alpha-thalassaemia: a case report.

We report a case of homozygous alpha-thalassaemia with hydrops fetalis presenting at 22 weeks of gestation. In utero exchange transfusion was performed with maternal blood at 23 weeks. 25 weeks and 29 weeks of gestation. The fetus was delivered at 29 weeks of gestation without significant neonatal complication. Post-transfusion haemoglobin pattern after transfusion suggested that a total haematocrit of 0.52 may be the desired post-exchange transfusion haematocrit to aim for and the total haematocrit of haemoglobin A and haemoglobin Portland dropped approximately one percent per day.

Adult↗

Routine analysis of plasma busulfan by gas chromatography-mass fragmentography.

Busulfan (BU) is a widely used alkylating agent for antineoplastic therapy and marrow ablation in preparation for bone marrow transplantation (BMT). High-dose BU often leads to successful preparation and low relapse but is associated with veno-occlusive disease of liver. We established a protocol to determine postdosage plasma BU concentrations by gas chromatography-mass fragmentography in an attempt to relate clinical outcome to plasma BU concentrations. We used nonisotopic pusulfan as the internal standard. After extraction into ethyl acetate, BU and pusulfan were iodinated into 1, 4-diiodobutane and 1,5-diiodopentane, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out on an Hewlett-Packard (HP) 5890II gas chromatograph with a 30-m 100% methyl silicon narrow bore, fused-silica capillary column interfaced with an HP 5970A mass spectrometer. Helium was the carrier gas. The sample molecules were identified by total ion monitoring and quantified by selective ion monitoring of m/z 183 and 197. The calibration curve was linear to 4 mg/L. The limit of quantification was 0.04 mg/L, and the analytical recovery was approximately 97%. The within-day and between-day imprecision (CV) was <6% and 9%, respectively. In a preliminary study of 12 children, the BU areas under the BU-time curve were 616-949 micromol. min/L after the first dose and 793-1143 micromol. min/L after the fifth dose. We conclude that the GC-MS procedure is suitable for routine analysis of plasma BU.

Adolescent↗

Echocardiographic evaluation of cardiac function in paediatric oncology patients treated with or without anthracycline.

Using Doppler echocardiography, we studied the left ventricular systolic and diastolic function in 124 healthy control children (group C), 110 oncology patients who had received anthracycline (group A), and 76 oncology patients who had received chemotherapy not including anthracycline (group N), at rest and after supine bicycle exercise. The mean dosage of anthracycline that group A patients received was 219 +/- 95 mg/m2. Impaired systolic function was detected in 29% of the patients in group A and 4% in group N. Figures for impaired diastolic function for group A and N were 27% and 28% respectively. Abnormal diastolic function was detected more frequently in the first two years after chemotherapy in both groups. Four parameters measured at rest appeared to be specifically abnormal in group A but not in group N. These were ejection fraction, fractional shortening, rate-corrected velocity of circumferential fiber shortening (VCFC) and left ventricle peak systolic wall stress (LVWS). After exercise more parameters were abnormal in group N patients when compared to normal children, but abnormalities of VCFC and LVWS remained specific for group A. In conclusion, abnormalities of diastolic function were common among paediatric oncology patients no matter whether they had received anthracycline treatment or not. Abnormalities of systolic function were more specific to anthracycline toxicity. VCFC and LVWS were the most sensitive measurements for differentiating group N patients from group A patients.

Adolescent↗

Pulsed magnetic and electromagnetic fields in experimental achilles tendonitis in the rat: a prospective randomized study.

OBJECTIVE: To investigate the effects of pulsed magnetic fields (PMF) and pulsed electromagnetic fields (PEMF) on healing in experimental Achilles tendon inflammation in the rat. DESIGN: Prospective randomized trial. SETTING: University medical school. METHODS: Exposure of the Achilles tendon and injury by a weight of 98.24 g falling from a height of 35cm in 180 male Sprague-Dawley rats. INTERVENTION: A daily 15-minute session with PMF of 17Hz or 50Hz, or PEMF of 15Hz or 46Hz, or a sham session. OUTCOME MEASURES: Random sacrifice 2 hours after the operation, and at 1, 3, 7, 14, or 28 days. Assessment of water content, weight, and histological appearance of the tendons. RESULTS: The time from injury and the various treatment modalities exerted a significant influence on the water content of the tendon after the injury (two-way ANOVA, p = .02). At day 3, the water content of the PEMF 46Hz group was significantly higher than in the other groups, decreasing sharply by day 7, and being similar to the other groups thereafter. By the end of the experiment, the PEMF 15Hz group was not significantly different from the control group. At day 7, the PMF 50Hz group showed significantly lower water content than the control group (p = .03), but at 14 days the PMF 50Hz group was not significantly different from the control group. PMF 50Hz suppressed the extravascular edema during early inflammation. PMF 17Hz showed a similar initial trend, producing a consistent lower water content throughout the experiment, reaching statistical significance by the end of treatment. By the end of the experiment, the collagen fibers had nearly regained their normal alignment in all groups, with a more physiological alignment seen in the PEMF 17Hz group. CONCLUSIONS: The tendon returned to histological normality in all groups, but the PMF 17Hz group showed better collagen alignment by the end of the study. PMF 17Hz resulted in a greater reduction of inflammation, with a better return of the tendon to histological normality. Different PMF and PEMF could be applied according to when treatment is started after the injury. If there is no delay between injury and beginning of pulsed magnetic treatment, PMF 17 should be used.

Achilles Tendon↗

Sonographic appearance of hepatic Langerhans cell histiocytosis.

Periportal lesions were detected on ultrasound in two cases of Langerhans cell histiocytosis with liver involvement. Hypoechoic or hyperechoic lesions were detected in different stages of evolution. Hyperechoic lesions probably corresponded to periportal inflammation whilst hyperechogenicity suggested xanthomatous change.

Disease Progression↗