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Biomedical subjects

T K Chan

Publications and source records attributed to T K Chan.

At least 127 records · Page 7Linked to original sources
PubMed1990

Histologic subtypes and survival of Chinese patients with non-Hodgkin's lymphomas.

The histologic subtypes and survival of 840 Chinese patients with non-Hodgkin's lymphoma (NHL) were reviewed. All cases were classified according to the Rappaport and Kiel systems and the Working Formulation (WF). A low incidence of nodular/follicular lymphomas (12%) was observed. The most common histologic subtypes were diffuse histiocytic, diffuse centroblastic, and diffuse large cell lymphomas, according to Rappaport, Kiel, and the WF, respectively. A high proportion (24%) of the cases were unclassifiable, according to Kiel, because of the precise terms of the classification. The "favorable"-prognosis NHL, according to Rappaport, or the low-grade NHL, according to Kiel and the WF, had a more indolent clinical course. However, except for the nodular mixed (Rappaport) or follicular mixed (WF) lymphomas which appeared to behave like the more aggressive NHL, a plateau was not seen in the survival curves of our patients with other kinds of favorable-prognosis or low-grade NHL, indicating the lack of curative potential of these tumors. The lymphoplasmacytoid lymphoma, according to Kiel, also appeared to have a more aggressive clinical course. A plateau was seen in most of the other survival curves of patients with the more aggressive tumors, indicating the prospect of cure. However, the prognosis of the very aggressive tumors such as the diffuse lymphoblastic and diffuse small noncleaved cell lymphomas, according to the WF, remains very poor with a median survival of less than 10 months.

Adolescent↗
PubMed1990

Induction chemotherapy for newly diagnosed acute myeloid leukaemia using a regime containing cytosine arabinoside, daunorubicin and etoposide.

A total of 46 patients with previously untreated acute myeloid leukaemia were treated with an induction regimen consisting of 100 mg/m2 cytosine arabinoside given daily by 18-h i.v. infusion for 7 days, 50 mg/m2 daunorubicin given daily by i.v. bolus injection for 3 days and 75 mg/m2 etoposide given daily by 1-h i.v. infusion for 7 days. In all, 30 patients (67%) went into complete remission and were given further consolidation and maintenance chemotherapy. Of the 31 complete responders, 15 (48%) relapsed. The median disease-free survival of the 31 complete responders and the median overall survival of all 46 patients were 25 and 14 months, respectively. None of the clinical characteristics, which included sex, age, FAB morphology, extramedullary disease and initial WBC count, predicted the clinical response. Myelosuppression was the major toxicity and non-haematological side effects were acceptable. The regimen appeared to have acceptable toxicity, and its efficacy was comparable with that of standard regimens.

Adolescent↗
PubMed1990

Investigation of intravascular haemolysis during treatment of acute stroke with intravenous glycerol.

1. In patients with acute strokes entering a large ongoing randomised double-blind controlled trial of intravenous glycerol therapy, the extent and pathogenesis of any ensuing haemolysis were evaluated using standard clinical investigations and in vitro techniques. 2. Twenty patients received 10% glycerol in saline (500 ml over 4 h on 6 consecutive days) and 15 received corresponding control treatment with saline. 3. Intravascular haemolysis was evident after the first infusion; compared with the controls the glycerol group had i) a greater mean reduction in serum haptoglobin concentration (P less than .05), and ii) a greater proportion exhibiting haemoglobinaemia (P = 0.03). 4. After 6 days of glycerol treatment, the mean reduction in haemoglobin concentration was only 0.8 g more than in controls; this difference being neither clinically nor statistically significant. 5. Glycerol therapy was not associated with haemoglobinuria, renal insufficiency or disseminated intravascular coagulation. 6. Exposure of red blood cells to 1-10% glycerol in vitro did not induce haemolysis per se; on re-exposure to lower concentrations lysis ensued provided a minimum osmotic gradient was present. 7. Whilst taking standard dosage regimes of glycerol, the stroke patients we studied manifested a degree of intravascular haemolysis but its consequences were not clinically significant; lysis probably ensued after venous blood acquiring high glycerol concentrations mixed with blood containing little or no glycerol.

Acute Disease↗
PubMed1990

Ofloxacin versus co-trimoxazole for prevention of infection in neutropenic patients following cytotoxic chemotherapy.

The efficacy of ofloxacin in preventing infection in neutropenic patients following cytotoxic chemotherapy was evaluated and was compared with that of co-trimoxazole. A total of 102 patients with hematological malignancies were randomly selected to receive either co-trimoxazole or ofloxacin. All patients were monitored for compliance, occurrence of infection, and drug-related side effects. A surveillance culture of a rectal swab was performed regularly. A total of 25 of the 52 patients (48%) who received co-trimoxazole and 11 of the 50 patients (22%) who received ofloxacin developed fever during the study period (P less than 0.025). Gram-negative bacteremia occurred in nine patients in the co-trimoxazole group (17%) but in only one patient (2%) in the ofloxacin group (P less than 0.05). No patient in either group had documented gram-positive bacterial or Pneumocystis carinii infection. Poor performance status was the only identifiable factor associated with an increased incidence of bacteremia. The surveillance study showed that significantly fewer bacterial strains were resistant to ofloxacin than to co-trimoxazole and that acquisition of resistance to co-trimoxazole was more commonly observed than was acquisition of resistance to ofloxacin. Significantly more patients had skin rashes following co-trimoxazole than ofloxacin treatment (P less than 0.05). Ofloxacin was superior to co-trimoxazole in preventing infection in this population of neutropenic patients.

Adolescent↗
PubMed1990

Ceftazidime versus imipenem-cilastatin as initial monotherapy for febrile neutropenic patients.

One hundred febrile episodes in 89 neutropenic patients after cytotoxic chemotherapy were randomized to be treated with either ceftazidime or imipenem as initial monotherapy. The clinical characteristics of the two groups of patients were comparable. The response of the fever in patients who received imipenem was significantly better than that in those who received ceftazidime (77 versus 56%, respectively; P = 0.04), especially in those with microbiologically documented infection (81 versus 33%, respectively; P = 0.02). The in vitro susceptibilities and the clinical responses suggested that, with the possible exception of Pseudomonas spp., imipenem was more effective than ceftazidime in treating neutropenic infections caused by both gram-positive and -negative organisms. An additional 23 and 21% of the patients in the ceftazidime and imipenem groups, respectively, responded to the addition of cloxacillin and amikacin following failure of monotherapy. The majority of the treatment failures, relapses, and superinfections were related to resistant infective organisms such as methicillin-resistant Staphylococcus spp. and Pseudomonas spp. or disseminated fungal infections.

Adolescent↗
PubMed1990

Immunoglobulin gene rearrangement in the peripheral blood and bone marrow of patients with lymphomas of the mucosa-associated lymphoid tissues.

The theory of 'homing' mechanism has been proposed to explain the association of malignant lymphoma involving multiple sites of mucosa-associated lymphoid tissue (MALT). DNA rearrangement in the peripheral blood and bone marrow specimens of 20 patients with MALT lymphoma were studied utilizing JH and C beta gene probes, aiming to detect circulating lymphoma cells and unrecognized bone marrow involvement. Our search for malignant cells in the peripheral blood was unrewarding and the 'homing' theory remained unproven. However, the study of DNA rearrangement showed to be useful in determining the malignant nature of abnormal lymphoid aggregates found in the bone marrow of these patients.

Adult↗
PubMed1990

Cerebral thrombosis in beta-thalassemia/hemoglobin E disease.

We describe two Chinese patients with beta-thalassemia/hemoglobin E disease who developed cerebral infarction due to occlusion or stenosis of their extracranial carotid arteries. The roles of platelet abnormalities and other factors in this condition are discussed.

Adult↗
PubMed1989

Treatment of adult acute lymphoblastic leukaemia using an intensive chemotherapy protocol.

A total of 25 evaluable adult patients with acute lymphoblastic leukaemia (ALL) were treated with an intensive chemotherapy regime modified from the L17/L17M protocol of the Sloan-Kettering Hospital. There were 18 men and 7 women; their median age was 36 years (range, 13-78). Seven cases had L1 morphology and 18, L2. The immunophenotype was common-ALL in 10, null-ALL in 9, T-ALL in 4 and B-ALL in 1. Of the 25 patients, 14 (56%) achieved a complete remission (CR). The causes of induction failure were partial remission (PR) only in 7 (28%) and hypoplastic death in 4 (16%). Of the 14 CR patients, 11 (78.6%) relapsed. Five patients developed CNS disease. The median disease-free survival and overall survival were only 9 and 13 months, respectively. As the follow-up periods of the surviving patients were short, late relapses may still occur and the overall treatment result is likely to be worse on longer follow-up. The possible causes of this disappointing result are discussed.

Adult↗
PubMed1989

Central nervous system involvement in non-Hodgkin's lymphoma.

Fifty-eight Hong Kong Chinese patients with CNS lymphoma were reviewed (primary seven, secondary 51). The incidence of secondary CNS lymphoma in patients with non-Hodgkin's lymphoma was estimated to be 9.4%. The Working Formulation separated subtypes which had a special propensity to involve the CNS. Significant proportions of our patients with secondary CNS lymphoma had other features which were known to be associated with a high risk of CNS disease including stage IV (48/51, 91.4%), bone marrow (26/51, 50.9%), peripheral blood (7.51, 13.7%), nasal (7/51, 13.7%), orbital (3/51, 5.9%), testicular (2/51, 3.9%) and bulky retroperitoneal (6/51, 11.8%) disease. 82% of patients with secondary CNS lymphoma had concurrent systemic disease and a further 12% had systemic relapse shortly afterward. CNS lymphoma is associated with poor prognosis and only 29% and 14% of the patients with primary and secondary CNS lymphoma respectively survived beyond 1 year. Patients responding to therapy had significantly better survival. 69.9% of the deaths were related to progressive systemic disease.

Adolescent↗
PubMed1989

Multiple XbaI polymorphisms for carrier detection and prenatal diagnosis of haemophilia A.

Three XbaI restriction fragment length polymorphisms (RFLPs) can be detected using the factor VIII-intron 22 probe (p482.6) in a XbaI-KpnI double digest of genomic DNA. The XbaI (A) site had been reported by Wion et al (1986) to be in intron 22, while the two additional sites. XbaI (B) and XbaI (C), are shown here to be X-linked and close to the XbaI (A) site. The frequencies of heterozygosity for these three sites are 0.49, 0.18 and 0.30 respectively. In 75 females the observed heterozygosity rate for the XbaI (A) site is 0.41 and this increased to 0.57 with the two additional sites. Care should be exercised when interpreting the XbaI RFLPs, since the 1.4 kb XbaI/KpnI fragment and the 4.8 kb XbaI fragment are associated with both positive XbaI (A) and XbaI (B) sites. By the combined use of the multiple XbaI polymorphisms with the BclI site in intron 18, the carrier detection rate would increase to 67%. Four prenatal diagnoses had been performed using the multiple XbaI polymorphisms.

Factor VIII↗
PubMed1989

Acute lymphoblastic leukemia in Chinese adults in Hong Kong.

Forty-four previously untreated Chinese adult patients with acute lymphoblastic leukemia (ALL) were treated with vincristine, adriamycin and prednisone with or without L-asparaginase. The clinical features and prognostic factors were similar to those reported in Caucasian series. Overall complete remission (CR) rate was 52%. Duration of first remission and overall median survival were nine and 12 months respectively. The addition of L-asparaginase did not improve CR rate or duration of remission and was associated with clotting dysfunction and other adverse reactions. Factors associated with a higher CR rate include age less than 40 years, blast count less than 10 x 10(9)/l and CALLA + phenotype at presentation. Sex, platelet count and FAB morphology did not affect CR rate. Bone marrow relapse occurred in 11 patients and was associated with short survival after relapse (median two months; mean two months; range 0.5-7 months). Central nervous system relapse occurred in four patients and was compatible with relatively long survival after relapse (median 13 months; mean 12 months; range 6-12 + months). The poor CR rate and short median survival in this study could not be adequately explained by an increase in risk factors and is likely to be due to what is currently regarded as suboptimal chemotherapy.

Adolescent↗
PubMed1989

Fulminant hyperpyrexia induced by bleomycin.

Mild and self-limiting fever following bleomycin use is common, and a fatal hyperpyrexial response occurs rarely. In previously reported cases, such hyperpyrexia occurred either after the initial administration of the drug or during subsequent therapy following an initial pyrexial response. We describe a fatal hyperpyrexial reaction after bleomycin in a patient with T-cell lymphoma who had had no febrile response when she received her initial injection 3 weeks earlier. Since the occurrence of this hyperpyrexial response is unpredictable, health care workers as well as patients and relatives should always be alert to this potentially lethal complication and prompt measures should be taken in any patient who develops fever after bleomycin use.

Adult↗
PubMed1989

Cardiac tamponade complicating leukaemia: immediate chemotherapy or pericardiocentesis?

Although leukaemic infiltration of the pericardium is frequently observed at post-mortem, clinically evident cardiac tamponade is rare. Two cases of cardiac tamponade complicating leukaemia are presented. One patient had cardiac tamponade as the initial presentation of acute lymphoblastic leukaemia and experienced complete resolution of the pericardial effusion within 6 days after chemotherapy without therapeutic pericardiocentesis. The other patient with chronic myeloid leukaemia developed cardiac tamponade requiring pericardiocentesis as the first sign of acute blastic transformation. The roles of early chemotherapy and pericardiocentesis in managing this complication are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Granulocytic sarcoma presenting as bleeding gastric polyp.

Granulocytic sarcoma may develop before, after or at the time of presentation of acute myeloid leukemia. We report an unusual case in which the first manifestation of leukemic conversion of myelodysplastic syndrome was bleeding from a polypoid gastric granulocytic sarcoma.

Female↗
PubMed1989

The significance of thrombocytopenia in the development of postoperative intracranial hematoma.

A group of 35 patients undergoing intracranial surgery who exhibited perioperative thrombocytopenia (platelet count less than 150,000/microliters) was studied retrospectively. Of the 35 patients, 14 (40%) developed postoperative intracranial hematomas requiring reoperation and seven (20%) died within 2 weeks after the operation. Analysis revealed that a perioperative platelet count below 100,000/microliters in a patient who failed to respond to platelet transfusions was associated with a higher risk of postoperative hematoma formation. All six patients with this profile developed postoperative hematomas. If the platelet count rose promptly from below 100,000/microliters to a normal level after platelet transfusions, the incidence of hematoma formation decreased dramatically. None of the three patients with this response developed postoperative hematoma. In patients in whom an acute drop in platelet count from the normal range to between 100,000 and 124,000/microliters occurred in the immediate perioperative period, there was a significantly higher change of hematoma formation; this finding has not hitherto been described. Of the 14 patients with this clinical course, eight developed postoperative hematoma after craniotomy for tumors and vascular lesions. This latter observation was substantiated by the fact that thrombocytopenic patients with postoperative hematomas had a greater reduction in platelet count than thrombocytopenic patients with no postoperative hematomas (p = 0.0004).

Aged↗
PubMed1989

Fatal reactivation of chronic hepatitis B virus infection following withdrawal of chemotherapy in lymphoma patients.

Four Chinese patients with non-Hodgkin's lymphoma and asymptomatic chronic hepatitis B infection developed fulminant hepatitis three to four weeks after two to five courses of chemotherapy. One was initially positive for hepatitis B e antigen and three were positive for antibody to HBeAg. They had normal initial serum aminotransferase levels. In all four patients, the hepatic illness appeared to be caused by reactivation of hepatitis B virus replication as evidenced by the appearance of HBV DNA in serum at the onset of hepatitis, seroreversion from anti-HBe to HBeAg positivity, and the absence of other incriminating drugs or viral markers. All died within three weeks after the onset of jaundice. Serum HBV DNA level dropped to undetectable level as the hepatitis progressed. We postulate that potent cytotoxic therapy reactivated HBV replication and permitted widespread infection of hepatocytes. Upon withdrawal of chemotherapy, the immunologic rebound resulted in rapid destruction of infected hepatocytes and massive liver necrosis. Several methods for the prevention of such hepatic reactivation are discussed.

Adult↗