The survival of glucose-6-phosphate dehydrogenase--deficient erythrocytes in patients with typhoid fever on chloramphenicol therapy.
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Adolescent↗
Biomedical subjects
T K Chan
Publications and source records attributed to T K Chan.
The time course of red cell lysis in hypotonic electrolyte solutions.
1. Osmotic haemolysis of a standard suspension of human red cells was followed using a recording spectrophotometer at wave-lengths between 600 and 650 mmu.2. Optical density changes in the cell suspensions were related to turbulence of the suspension, cell swelling and loss of haemoglobin-containing cells.3. The time course of the loss of cells from suspension in hypotonic electrolyte solutions showed two phases: an early rapid phase was followed by a smaller phase of longer half-time.4. The second phase was most prominent in the middle ranges of partial haemolysis and less when total haemolysis was at the extremes of the detectable range.5. The second phase was eliminated by the inclusion of 20 mM sucrose in the suspension, and was slowed by the presence of 0.005% tannic acid without alteration of magnitude.6. The magnitude of the second phase was dependent on the dominant external cation, becoming progressively greater through the series: Mg(2+) < Na(+) < Li(+) < K(+) < Rb(+).7. The slow phase is interpreted as arising from passive cation permeability in cells swollen to a volume close to that critical for haemolysis, with water influx secondary to the unopposed colloid osmotic pressure of intracellular protein.
Cell Membrane Permeability↗
Erythrocyte glucose-6-phosphate dehydrogenase activity in haemoglobin H disease.
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Erythrocytes↗
Tissue enzyme levels in erythrocyte glucose-6-phosphate dehydrogenase deficiency.
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Adolescent↗
Gastrointestinal lymphoma in Chinese: a retrospective analysis.
Eighty-four Chinese patients with gastrointestinal lymphoma were reviewed. There were 45 gastric and 39 intestinal lymphomas. The median age was 45 years and the male to female ratio 1.14:1. Diffuse histiocytic (60 per cent) or diffuse large cell (53.5 per cent) lymphoma comprised a majority of the cases. A high incidence of gastrointestinal bleeding at presentation was observed in our patients. According to a modified staging classification, a larger proportion of patients with intestinal lymphoma had advanced disease (Stage III and IV) than those with gastric lymphoma (82 per cent versus 55 per cent, p less than 0.02) and gastric lymphoma carried a better prognosis. The modified staging classification used in this study appeared to stratify better the patients into 2 sub-groups of localized (Stage I and II) and advanced (Stage III and IV) disease, which correlated very well with the prognosis. Good treatment results were obtained following intensive therapy in our patients with localized disease (Stage I and II). The poorer treatment results of patients with advanced disease (Stage III and IV) call for better chemotherapy regimens and earlier diagnosis. Surgical resection of the primary gastrointestinal lesion is recommended to prevent haemorrhage and perforation following chemotherapy, which occurred in 38 per cent of our patients whose gastrointestinal lesions were not resected.
Adolescent↗
Follicular non-Hodgkin's lymphoma in Hong Kong Chinese: a retrospective analysis.
Follicular lymphoma is relatively rare in Hong Kong Chinese. Fifty-two patients with follicular lymphoma were reviewed. The histology was nodular lymphocytic poorly differentiated (NLPD) in 75 per cent, nodular mixed (NM) in 21 per cent and nodular histiocytic (NH) in 4 per cent. Our patients appeared to have a higher proportion of NLPD and a lower proportion of NM lymphoma than the western series. Fifty patients were analysed excluding the two patients with NH lymphoma. They had a median age of 50 and a male to female ratio of 0.92. Seventy-two per cent of them presented with asymptomatic lymph node enlargement. Twenty per cent had B symptoms and 32 per cent bulky tumour. Twelve per cent had stage I disease, 2 per cent stage II, 30 per cent stage III and 56 per cent stage IV. A high incidence of bone marrow involvement (48 per cent of all patients) was found. All seven stage I-II patients responded to involved-field radiotherapy alone and none of them has relapsed. The 43 stage III-IV patients were treated with chemotherapy without deferral and a majority of them received CVP (51.1 per cent) or chlorambucil alone (34.9 per cent). The complete response rate of stage III-IV patients was 81 per cent and 26 per cent of the complete responders relapsed. The 5-years disease-free survival (DFS) and overall survival of all patients (stage III and IV) were 50 per cent and 65 per cent respectively. The DFS curve showed a pattern of continuous relapses. Stage III patients appeared to have a better complete response rate, a lower relapse rate and superior disease-free survival than stage IV patients but the differences did not reach statistical significance. However, the overall survival of stage III patients was significantly better than stage IV patients (p less than 0.02). Other factors including sex, age, presence of bulky tumour, B symptoms, histologic subtypes and the chemotherapeutic regimes did not significantly affect their prognosis.
Adolescent↗
Hodgkin's disease in Hong Kong Chinese.
A lower incidence of Hodgkin's disease in Orientals has been recognized. Although most Hong Kong Chinese came from the Guandong province of China, the incidence of Hodgkin's disease in Hong Kong Chinese is 9.2 per cent which is more comparable to the low figure of 6 per cent in Japan than the 32 per cent incidence in Guangdong. If this discrepancy in the ethnically similar populations is confirmed, other etiological or promoting factors must be considered. Ninety-two Hong Kong Chinese patients (54 males and 38 females) with Hodgkin's disease were reviewed. The median age was 34 years (range 5-79 years). The histology was lymphocyte predominant in nine (10 per cent), nodular sclerosing in 34 (37 per cent), mixed cellularity in 29 (31 per cent), lymphocyte depleted in nine (10 per cent) and unclassified in 11 (12 per cent). Seventeen per cent had stage Ia disease, 2 per cent Ib, 15 per cent IIa, 11 per cent IIb, 11 per cent IIIa, 9 per cent IIIb, 11 per cent IVa and 24 per cent IVb. Twenty-five of them (27 per cent) were staged by laparotomy. Twelve patients (13 per cent) had bulky disease. Identical to the pattern observed in Caucasians, our patients had an apparent biomodal age distribution, a male predominance and similar distribution of histological subtypes according to the Rye classification. The absence of an early peak in young adulthood and the lower incidence of the nodular sclerosing subtype reported in the Japanese was not observed in our patients. A variety of treatments were given to the 92 patients. Most of the patients with stage I-II disease received radiotherapy except for those with B symptoms, bulky disease or lymphocyte depleted histology, who received chemotherapy with or without radiotherapy. All patients with stage III-IV disease received chemotherapy with or without radiotherapy except for two patients with stage IIIa disease who had total nodal irradiation only. The multivariate analysis revealed that Ann Arbor staging was a significant independent factor determining the disease-free survival of patients in complete remission and the overall survival of all patients. Age was the other independent variable significantly determining the overall survival.
Adolescent↗
Long-term follow-up of patients receiving salvage chemotherapy for intermediate and high grade non-Hodgkin's lymphomas.
This is an analysis of the long-term follow-up data of 99 patients receiving HOAP-Bleo, IMVP-16 and PAC as salvage chemotherapy for refractory or relapsed intermediate or high grade non-Hodgkin's lymphomas. Most of the patients received HOAP-Bleo or PAC following failure of initial chemotherapy and IMVP-16 was used mainly for HOAP-Bleo failures. The longest follow-up time of the surviving patients was 108 months. Twenty-two and 29 per cent of the patients survived beyond 2 years following HOAP-Bleo and PAC respectively. The treatment outcome following IMVP-16 was worst with a 2-year survival of only 5 per cent, as it was used mainly following HOAP-Bleo failures. Although the prognosis of these refractory or relapsed cases are poor, salvage treatment is still worthwhile as a small proportion of these patients may have long-lasting remissions and occasional patients may be cured. Newer approaches such as autologous bone marrow transplantation should be compared with current salvage chemotherapy regimens.
Adult↗
Management of advanced stage intermediate grade non-Hodgkin's lymphomas.
The treatment result of 271 cases of advanced stage intermediate grade lymphoma were reviewed. Ninety-four patients received CHOP chemotherapy, 45 BACOP and 17 m-BACOD. The clinical characteristics of the three groups of patients were comparable. Patients receiving CHOP had a complete response (CR) rate of 60 per cent, the disease-free survival of CR patients was 31 per cent at 5 years. The overall survival following CHOP chemotherapy was 38 per cent at 5 years. The use of the BACOP or m-BACOD regime did not appear to improve significantly the prognosis of these patients. Clinical staging, B symptoms, age and serum lactate dehydrogenase level were the most important independent prognostic factors.
Analysis of Variance↗
Hepatitis B infection in patients with lymphomas.
This paper reviewed the clinical characteristics and treatment outcome of 484 lymphoma patients with known hepatitis B status. Comparisons were made between the hepatitis B surface antigen positive and negative patients. Also, the effect of treatment for lymphomas, including cytotoxic chemotherapy, in the hepatitis B antigen positive patients were analysed. The hepatitis B status was determined in 484 Chinese lymphoma patients at the time of initial diagnosis. Hepatic complications occurring during therapy for lymphomas were analysed. Although our lymphoma patients had a similar prevalence of hepatitis B markers of 42 per cent, they had a strikingly higher positive rate of 22 per cent for hepatitis B surface antigen and a relatively lower positive rate of 20 per cent for antibody, as compared to the respective figures of 9.5 per cent and 33 per cent in the control population. The hepatitis B surface antigen positive patients were younger than the negative patients but their treatment outcomes were similar despite the higher incidence of hepatic complications (21 per cent) in the hepatitis B surface antigen positive patients during therapy for lymphomas. None of the clinical parameters analysed appeared to be useful in predicting the development of these complications which included fatal liver failure (5.7 per cent), icteric hepatitis (5.7 per cent) and anicteric hepatitis (9.5 per cent). The high prevalence of hepatitis B surface antigen in our lymphoma patients may be related to the immunosuppressive effect of lymphomas. There is no definite evidence to suggest that hepatitis B infection has an aetiological or promoting role in the pathogenesis of lymphomas. Hepatitis B infection has contributed to the high incidence of hepatic complications during therapy for lymphomas and possible ways of prevention need to be investigated.
Adolescent↗
Primary and secondary cutaneous lymphomas in Hong Kong Chinese.
Sixty-eight Hong Kong Chinese patients with cutaneous lymphomas were studied. There were 38 males and 30 females and their median age was 52 years. According to a staging system as proposed by the Mycosis Fungoides Cooperative Group, 48 (71 per cent) of the patients had disseminated stage IV disease. There were nine (13 per cent) cases of mycosis fungoides. The remaining cases were mostly intermediate or high grade non-Hodgkin's lymphomas according to the Working Formulation. Immunophenotyping was performed in 23 cases and in 17 cases (74 per cent), T-cell tumours were identified. Many of these T-cell lymphomas were unclassifiable according to the Working Formulation and were either pleomorphic or immunoblastic-lymphadenopathy-like T-cell lymphoma according to a modified system of the Japanese Lymphoma Study Group. A variety of therapies were given to these patients and those with stage IV disease had a significantly poorer survival. On the other hand, the histology, and immunophenotype did not appear to be useful in predicting prognosis.
Adolescent↗
Detection of immunoglobulin gene rearrangement in B-cell lymphomas by polymerase chain reaction gene amplification.
This is a report on our attempt to use polymerase chain reaction (PCR) to detect rearrangement of the immunoglobulin gene in the tissue specimens obtained from 30 patients with non-Hodgkin's lymphomas. There were 20 B-cell lymphomas and 10 T-cell. All 20 B-cell lymphomas but none of the 10 T-cell lymphomas had JH rearrangement by Southern analysis. Two pairs of primers (V670/OL-4 and VH26/OL-4) were designed to amplify the CDR3 region of the immunoglobulin gene heavy chain. The PCR analysis was positive using either one or both pairs of primers in 11 of the the 20 cases (55 per cent) of B-cell lymphomas which all had positive rearrangement by Southern analysis. The two pairs of primers seemed to produce complementary results as the specimens may be positive to one pair but negative to the other. The false negative rate of 45 per cent is however much higher than the respective figures of 18 per cent and 0 per cent observed in our patients with acute lymphoblastic leukemia and chronic lymphocytic leukemia in a previous study. Peripheral blood and bone marrow biopsy specimens obtained at the time of initial diagnosis were available from 10 patients with B-cell lymphomas whose lymph node biopsy specimens at the time of diagnosis were positive by both Southern analysis and PCR. All these peripheral blood and marrow specimens had no microscopic evidence of involvement by lymphoma cells and JH rearrangement was not detected by Southern analysis. However, rearranged bands identical to that of the lymph node biopsy specimen were detected by PCR in the peripheral and marrow blood of one of them. This PCR technique has been shown to have a sensitivity of 0.1 per cent in our previous report and may be more useful than morphology alone or Southern analysis in detecting minimal lymphomatous involvement in the peripheral blood and bone marrow at the time of initial diagnosis. Further clinical correlation is required to confirm the finding.
Base Sequence↗
Intensive chemotherapy for peripheral T-cell lymphomas.
Forty-two patients with previously untreated peripheral T-cell lymphomas (PTCL) were treated with an intensive chemotherapy protocol. Either the BACOP or the m-BACOD regimen was used for induction. Patients achieving complete clinical remission after three courses were given intensive consolidation and maintenance chemotherapy similar to the L10/L17M protocol designed by the Memorial Sloan-Kettering Group for acute lymphoblastic leukemia and lymphoblastic lymphoma. There were 27 (64 per cent) males and 15 (36 per cent) females. The median age was 54 years (mean 53, range 15 to 68). Seven of them (17 per cent) had stage I disease, four (10 per cent) stage II, seven (17 per cent) stage III and 24 (57 per cent) stage IV. Eighteen patients (43 per cent) had B symptoms and four (10 per cent) had bulky disease. According to the Working Formulation, the histology was diffuse mixed in 16 patients (38 per cent), diffuse large cell in 18 (43 per cent), diffuse immunoblastic in four (10 per cent) and unclassifiable in four (10 per cent). According to a modified Japanese Lymphoma Study Group's classification, the histology in 24 patients (57 per cent) was the pleomorphic type, in 13 (31 per cent) immunoblastic-lymphadenopathy-like (IBL-like), and in five (12 per cent) unclassifiable. The overall complete remission rate was 67 per cent. Twenty-five per cent of the complete responders relapsed and the DFS of the CR patients was 62 per cent at three years. The overall survival of all patients at three years was 52 per cent. Patients with stage I, II and III disease had significantly better CR rate (100 per cent versus 42 per cent, p = 0.001) and overall survival (82 per cent versus 35 per cent at three years, p = 0.01) than those with stage IV disease but the relapse rate and DFS of CR patients were similar. This study shows that the prognosis of patients with PTCL can be improved by intensive therapy.
Adolescent↗
COPP chemotherapy for elderly patients with intermediate and high grade non-Hodgkin's lymphoma.
One hundred and forty-one consecutive patients above and 231 below the age of 60 years with previously untreated intermediate or high grade non-Hodgkin's lymphoma were included in this study. Patients above the age of 60 years were treated with the COPP chemotherapy regimen. The younger patients, at or below the age of 60, received a doxorubicin-containing regimen (119 had CHOP, 65 had BACOP and 47 had m-BACOD). For stage I patients, the clinical results were similar but for stage II, III or IV disease, those receiving COPP had significantly worse CR rate and survival than those who had a doxorubicin-containing regimen. Multivariate analysis on patients receiving the COPP chemotherapy revealed that the independent prognostic variables significantly determining CR rate and survival included clinical stage (p = 0.04) and serum lactate dehydrogenase level (p = 0.001). Myelosuppression was the major toxicity following COPP chemotherapy in this group of patients. There were 10 (7 per cent) treatment-related deaths. Compared to the reported results using doxorubicin-containing regimens to treat elderly patients with aggressive NHL in the literature, the more aggressive treatment does not appear to improve significantly the clinical outcome of this group of patients and seems to produce treatment results very much similar to COPP. However, accurate comparison is difficult because of the variation in the patient characteristics. Further prospective controlled randomized trials will be necessary to determine the optimal therapy for these patients.
Adolescent↗
Prognostic factors for primary gastrointestinal lymphoma.
The gastrointestinal tract is a common primary extranodal site for non-Hodgkin's lymphoma. There is however no uniform consensus on its pathological classification, clinical staging system and management. This paper reports the experience in the management of 425 Chinese patients with primary gastrointestinal lymphoma in Hong Kong from January 1975 to June 1993. There were 230 (54 per cent) males and 195 (46 per cent) females. Their median age was 53 years. The primary sites were: the esophagus in three (1 per cent), stomach in 238 (56 per cent), small intestine in 131 (31 per cent) and large intestine in 53 (12 per cent). According to the Working Formulation, there were 20 (4.7 per cent) small lymphocytic, 10 (2.4 per cent) follicular small cleaved cell, 15 (3.5 per cent) follicular mixed, five (1.2 per cent) follicular large cell, 40 (9.4 per cent) diffuse small cleaved cell, 50 (12 per cent) diffuse mixed, 181 (43 per cent) diffuse large cell, 30 (7.1 per cent) immunoblastic, five (1.2 per cent) lymphoblastic, 10 (2.4 per cent) diffuse small non-cleaved cell and 50 (14 per cent) unclassifiable lymphoma. Immunophenotyping was performed in 199 (47 per cent) patients: 90 per cent B-cell, 7 per cent T-cell and 3 per cent uncertain. According to a Manchester system, 81 (19 per cent) patients had stage I disease, 44 (10 per cent) stage II, 85 (20 per cent) stage III and 215 (51 per cent) stage IV. B symptoms were present in 275 (65 per cent) patients and bulky disease in 104 (25 per cent). Surgery followed by chemotherapy was the mainstay of treatment. Of the 408 patients treated, 63 per cent had a complete remission with relapse rate of 42 per cent. For those with complete remission, 47 per cent were free from disease at 5 years. The overall median survival of all patients was 45 per cent at 5 years. Multivariate analysis revealed that significant independent prognostic factors predicting better survival were young age of < 60 years, low grade histology, stage I and II disease and absence of bulky tumour. For gastric lymphoma, aggressive surgery did not significantly improve their outcome. Chemotherapy appears to play an important role in the management of gastrointestinal lymphoma. Better classification of the primary gastrointestinal lymphoma and more refined stratification of the patients according to the prognostic variables may allow individualization of treatment. Prospective randomized studies are essential to define the relative roles of surgery, chemotherapy and radiotherapy.
Adult↗
Evaluation of a prenatal screening procedure for beta-thalassaemia carriers in a Chinese population based on the mean corpuscular volume (MCV).
Haemoglobin A2 (HbA2) levels were determined on 25 beta-thalassaemia carriers by the microcolumn method and were found to range from 4.5-7.2 per cent (mean 5.2 +/- 0.82 S.D.). The haemoglobin level (Hb), mean corpuscular volume (MCV), plasma ferritin and HbA2 levels were measured on a further 299 consecutive Chinese pregnant women at a gestation of less than 24 weeks. 18 patients (6 per cent) had HbA2 level greater than 4.5 per cent and were diagnosed to be beta-thalassaemic carriers. It was observed that all these patients had a MCV below 75 fl. If this level is selected in a screening procedure based on measurement of MCV alone all beta-thalassaemia carriers could be detected and 11 per cent of the population screened would require HbA2 estimation. At a lower cut-off level of 70 fl, 8 per cent of the population screened would require HbA2 measurement (a decrease of 27 per cent) but the detection rate will be lowered considerably (83 per cent). The high false positive rate at all cut-off levels of MCV was largely due to the prevalence of iron deficiency anaemia in the population. Estimation of plasma ferritin level in patients with low MCV will reduce this false positive rate, but there will be a considerable delay in diagnosis in patients with concomitant iron deficiency and beta-thalassaemia. The presence of iron deficiency in beta-thalassaemia carriers did not reduce their HbA2 level below the diagnostic range in this study.(ABSTRACT TRUNCATED AT 250 WORDS)
Erythrocyte Indices↗
Can defects in transferrin receptor 2 and hereditary hemochromatosis genes account for iron overload in HbH disease?
Iron overload was found to be the major cause of disability in Chinese HbH disease patients although they were not on regular blood transfusion. The transferrin receptor 2 (TFR2) and hereditary hemochromatosis (HFE) genes were examined to see if inheritance of these gene defects may be a possible cause of iron overload in 45 HbH patients. A novel intronic (IVS6 (+6) T-->A) mutation of the TFR2 gene was identified in one patient, and six others were found to carry a known missense mutation (exon 5, I238M) that was also present in one normal control subject. One HbH patient and one normal control carried the H63D mutation of the HFE gene. Since only eight out of 45 iron-overloaded HbH patients carry a defect in the TFR2 or HFE gene in the heterozygote state and their iron loading status was comparable to the matched controls without such defects, it would appear that the accumulation of excess iron in HbH disease is more likely a result of increase dietary absorption secondary to ineffective erythropoiesis.
Alleles↗
A prospective study of symptomatic bacteremia following platelet transfusion and of its management.
BACKGROUND: The danger of bacteremia due to contaminated platelets is not well known. There are also no established guidelines for the management of febrile reactions after platelet transfusion. STUDY DESIGN AND METHODS: To determine the risk of symptomatic bacteremia after platelet transfusion, 3584 platelet transfusions given to 161 patients after bone marrow transplantation were prospectively studied. Platelet bags were routinely refrigerated for 24 hours after transfusion. Septic work-up was initiated for a temperature rise of more than 2 degrees C above the pretransfusion value within 24 hours of platelet transfusion or a temperature rise of more than 1 degree C that was associated with chills and rigor. Diagnosis of bacteremia after platelet transfusion was made only when the pairs of isolates from the blood and the platelet bags were identical with respect to their biochemical profile, antibiotic sensitivity, serotyping, or ribotyping. RESULTS: Thirty-seven febrile reactions, as defined above, occurred. Bacteremia subsequent to platelet transfusion was diagnosed in 10 cases. There was a 27-percent chance (95% CI, 15-43%) that these febrile reactions represented bacteremia that resulted from platelet transfusion. For a subgroup of 19 patients with a temperature rise of more than 2 degrees C, the risk of bacteremia was 42 percent (95% CI, 23-64%). Septic shock occurred in 4 of the 10 bacteremic patients. A rapid diagnosis was possible because the involved bacteria were demonstrated by direct Gram stain of the samples taken from the platelet bags of all 10 patients. CONCLUSION: Significant febrile reactions after platelet transfusion are highly likely to be indicative of bacteremia. Routine retention of platelet bags for subsequent microbiologic study was useful in the investigation of these febrile reactions. Empiric antibiotic therapy is indicated.
Bacteremia↗