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Biomedical subjects

K H Mak

Publications and source records attributed to K H Mak.

At least 37 records · Page 2Linked to original sources
PubMed2001

Lipodystrophia centrifugalis abdominalis infantilis: two cases from China.

We report the first two Chinese patients with lipodystrophia centrifugalis abdominalis infantilis in China. The first patient was a 3-year-old girl who developed an area of hyperpigmented skin depression on the right groin which spread centrifugally to the abdomen and right lower chest. Later, another lesion developed on the neck. The second patient was a 4-year-old girl who developed multiple areas of skin depression on her bilateral groin, periumbilical region, right axilla, and chest. The lesions also extended centrifugally. Erythematous margins and lymphadenopathy were present in both cases. Inflammatory changes were found in the subcutaneous fat. The clinical pictures and histologic features supported the diagnosis of LCAI in both cases.

Abdomen↗
PubMed2001

Distally based sural neurocutaneous flaps for ankle and heel ulcers.

This study assessed the use of sural neurocutaneous flaps to repair chronic ulcers in difficult-to-cover areas around the ankle and heel. Follow-up of the 14 patients included in this study ranged from 6 months to 3 years after their operation. Total flap loss occurred in two patients, both of whom had rheumatoid arthritis complicated by vasculitis. Partial flap loss occurred in three patients; all were heel ulcers. Additional skin grafting procedures were required to cover their ulcers. A lateral malleolus ulcer in a patient with rheumatoid arthritis recurred after 1 year and had to be covered with a free parascapular flap. The sural neurocutaneous flap is thus a reliable means of resurfacing ulcers in the ankle and heel region. It requires no sacrifice of major peripheral vessels and may be a useful alternative for patients with poor peripheral pulses. Its use in the presence of vasculitis, however, needs further refinement.

Adult↗
PubMed2000

Emerging concepts in the management of acute myocardial infarction in patients with diabetes mellitus.

Although fibrinolysis has improved survival of patients after myocardial infarction (MI), such therapy is less likely to be administered to patients with diabetes. Furthermore, these patients present later (15 min) than nondiabetics. Moreover, even with the use of early potent fibrinolytic agents, patients with diabetes continued to suffer excessive morbidity and mortality. This finding is not related to the ability of fibrinolytic agents to restore complete reperfusion or increased risk of reocclusion of the infarct-related artery. Instead, the impaired ventricular performance at the noninfarct areas and metabolic derangements during the acute phase of MI may account for the adverse outcome. The efficacy of percutaneous coronary revascularization procedures for treatment of acute MI requires further evaluation. Therapeutic approaches should consider correcting these abnormalities to afford greater survival benefit for this subset of high-risk patients.

Angioplasty, Balloon, Coronary↗
PubMed2000

Hierarchy of risk based on history and location of prior myocardial infarction in the thrombolytic era. GUSTO-I Investigators.

BACKGROUND: Among patients receiving thrombolytic therapy for myocardial infarction, the outcome for those with a history of infarction is dramatically worse than for those with their first event. Methods And Results We performed a post hoc analysis of patients with a history of myocardial infarction enrolled in the Global Utilization of Streptokinase and TPA for Occluded arteries (GUSTO)-I trial, focusing on the impact of the location of their current and prior events on mortality rates. Within the first 24 hours, mortality rate was greatest among patients with a current infarction in a territory remote from their previous event. By 48 hours after examination, mortality rates among patients with a second anterior infarct had overtaken that among patients with a current inferior/prior anterior infarct. This hierarchy of risk persisted at both 30 days and 1 year (mortality rate at 1 year: current anterior/prior inferior 23.2% +/- 1.4%, current anterior/prior anterior 20% +/- 1.5%, current inferior/prior anterior 17% +/- 1.2%, current inferior/prior inferior 10.8% +/- 0. 9%). CONCLUSIONS: In patients with ST-elevation myocardial infarction on a background of prior infarction, the location of current and prior events predicts a hierarchy of short- and long-term risk of death.

Aged↗
PubMed2000

Risk of influenza A (H5N1) infection among health care workers exposed to patients with influenza A (H5N1), Hong Kong.

The first outbreak of avian influenza A (H5N1) occurred among humans in Hong Kong in 1997. To estimate the risk of person-to-person transmission, a retrospective cohort study was conducted to compare the prevalence of H5N1 antibody among health care workers (HCWs) exposed to H5N1 case-patients with the prevalence among nonexposed HCWs. Information on H5N1 case-patient and poultry exposures and blood samples for H5N1-specific antibody testing were collected. Eight (3.7%) of 217 exposed and 2 (0.7%) of 309 nonexposed HCWs were H5N1 seropositive (P=.01). The difference remained significant after controlling for poultry exposure (P=.01). This study presents the first epidemiologic evidence that H5N1 viruses were transmitted from patients to HCWs. Human-to-human transmission of avian influenza may increase the chances for the emergence of a novel influenza virus with pandemic potential.

Adult↗
PubMed2000

Platelet glycoprotein IIb/IIIa receptor antagonists and their use in elderly patients.

With increasing age of the general population, cardiovascular diseases are becoming a greater health burden. Coronary artery disease remains a major cause of morbidity and mortality worldwide. Among the various pathophysiological processes, platelets play a pre-eminent role. With the identification of the glycoprotein (GP) IIb/IIIa receptor as the final common pathway for platelet aggregation, potent antiplatelet agents have been developed. These GP IIb/IIIa antagonists have been shown to be effective in improving outcomes among patients undergoing percutaneous coronary interventions and for the treatment of acute coronary syndromes. By pooling the results of several large-scale trials, these benefits have been found to extend to the elderly population. Among 7860 patients undergoing percutaneous coronary intervention, the occurrence of death or myocardial infarction at 30 days was reduced from 10.0 to 5.9% (odds ratio 0.56; 95% confidence level, 0.37 to 0.83) with abciximab compared with placebo, in those >70 years of age. Importantly, this benefit was achieved without an increase in major bleeding complications. Similarly favourable trends were also observed among elderly patients treated with tirofiban or eptifibatide for acute coronary syndromes. As such, GP IIb/IIIa antagonists are effective in preventing ischaemic complications and can be safely administered to elderly patients.

Aged↗
PubMed1999

Cost-efficacy modeling of functional testing with perfusion imaging to detect asymptomatic restenosis following percutaneous transluminal coronary angioplasty.

The objective of this study was to perform a theoretical cost-efficacy analysis on the use of routine functional testing with perfusion imaging to identify patients with asymptomatic restenosis following percutaneous transluminal coronary angioplasty (PTCA) procedures. Approximately 50% of patients with restenosis following PTCA are asymptomatic. Routine functional testing is commonly performed at 3 to 6 months to identify these patients. The cost-efficacy associated with this strategy is unknown. Theoretical models were constructed based on assumed costs for functional testing (U.S. $1,300) and coronary angiography (U.S. $3,000). Restenosis rates were assumed to be 40%, and half of patients with restenosis were assumed to be asymptomatic. To provide a range of costs to identify a patient with asymptomatic restenosis, three scenarios were constructed based on the diagnostic test characteristics of functional testing. Sensitivity analyses were performed using a range of costs for functional testing, restenosis rates, and proportion of patients with restenosis who are asymptomatic. Depending on the diagnostic accuracy of functional testing, it costs $8,200 to $22,400 to identify an asymptomatic patient with restenosis following PTCA. The cost to identify a patient with asymptomatic restenosis varies inversely with the rates of restenosis. When restenosis rates are < 20%, the cost to identify a patient with asymptomatic restenosis exceeds $10,000. Similarly, the cost to identify a patient with asymptomatic restenosis increases when the proportion of patients with asymptomatic restenosis decreases. The cost, associated with the use of routine functional testing for the identification of asymptomatic patients with restenosis appears exorbitant. However, a formal study is warranted to determine the cost-efficacy of such a strategy. Cathet. Cardiovasc. Intervent. 48:352-356, 1999.

Angioplasty, Balloon, Coronary↗
PubMed1999

Platelet glycoprotein IIb/IIIa inhibition in acute coronary syndromes.

Acute coronary syndromes are a leading cause of hospitalization in industrialized countries. Current antithrombotic therapy focuses on relatively weak antiplatelet agents and heparin. The advent of inhibitors of the platelet glycoprotein IIb/IIIa receptor, the final common pathway for aggregation, provides a new therapeutic modality. Clinical trials with a total of more than 18,000 patients have clearly shown the benefits of intravenous IIb/IIIa blockade. Overall, at 30 days, 13 fewer deaths or myocardial infarctions occurred for every 1000 patients treated in these trials. This favorable outcome was extended to 6 months, resulting in 16 fewer such events per 1000 patients treated. Importantly, these benefits were not accompanied by an excessive occurrence in bleeding complications or thrombocytopenia. To further improve outcomes in this high-risk group of patients, strategies pertaining to prolonged periods of vessel passivation with oral formulations and early or delayed invasive approaches are being studied.

Acetates↗
PubMed1999

Diabetes mellitus: biological determinants of atherosclerosis and restenosis.

Diabetes mellitus is a potent risk factor for the development of atherosclerosis. Patients with diabetes account for approximately 20% of patients presenting with acute coronary syndromes or for percutaneous coronary intervention. Furthermore, the incidence of diabetes continues to increase world-wide, such that substantial medical resources are allocated for the care of patients with diabetic cardiovascular complications. Although great strides have been made in reducing cardiovascular events in recent years, there has been little improvement in outcomes for patients with diabetes mellitus. This review will focus in the underlying patho-biology and the current status of therapeutic interventional strategies for patients with diabetes mellitus.

Biological Factors↗
PubMed1999

Case-control study of risk factors for avian influenza A (H5N1) disease, Hong Kong, 1997.

In May 1997, a 3-year-old boy in Hong Kong died of a respiratory illness related to influenza A (H5N1) virus infection, the first known human case of disease from this virus. An additional 17 cases followed in November and December. A case-control study of 15 of these patients hospitalized for influenza A (H5N1) disease was conducted using controls matched by age, sex, and neighborhood to determine risk factors for disease. Exposure to live poultry (by visiting either a retail poultry stall or a market selling live poultry) in the week before illness began was significantly associated with H5N1 disease (64% of cases vs. 29% of controls, odds ratio, 4.5, P=.045). By contrast, travel, eating or preparing poultry products, recent exposure to persons with respiratory illness, including persons with known influenza A (H5N1) infection, were not associated with H5N1 disease.

Adolescent↗
PubMed1999

Antibody response in individuals infected with avian influenza A (H5N1) viruses and detection of anti-H5 antibody among household and social contacts.

The first documented outbreak of human respiratory disease caused by avian influenza A (H5N1) viruses occurred in Hong Kong in 1997. The kinetics of the antibody response to the avian virus in H5N1-infected persons was similar to that of a primary response to human influenza A viruses; serum neutralizing antibody was detected, in general, >/=14 days after symptom onset. Cohort studies were conducted to assess the risk of human-to-human transmission of the virus. By use of a combination of serologic assays, 6 of 51 household contacts, 1 of 26 tour group members, and none of 47 coworkers exposed to H5N1-infected persons were positive for H5 antibody. One H5 antibody-positive household contact, with no history of poultry exposure, provided evidence that human-to-human transmission of the avian virus may have occurred through close physical contact with H5N1-infected patients. In contrast, social exposure to case patients was not associated with H5N1 infection.

Adolescent↗
PubMed1999

Trends in mortality, incidence, hospitalisation, cardiac procedures and outcomes of care for coronary heart disease in Singapore, 1991-1996.

In this study, we used Singapore population-based data from 1991 to 1996 to examine recent trends in mortality, incidence and hospitalisation for acute myocardial infarction (AMI), and explored the roles of primary prevention and medical care interventions in explaining these trends. We examined trends in medical interventions, namely coronary angiography (catheterisation), coronary artery bypass graft (CABG), and percutaneous transluminal coronary angioplasty (PTCA), length of stay, and payment methods, and explored the roles of technological, healthcare financing and delivery, and regulatory factors in influencing the diffusion and outcomes of these medical interventions. During the period 1991 to 1996, there were parallel declines in resident population rates of mortality, incidence and hospitalisation for AMI. The rates of angiograms, CABG and PTCA among residents also increased greatly, with the greatest increase among elderly aged 60 years and above. The rates of invasive cardiac procedures for AMI were all lower in females than in males. The population case-fatality rate of AMI declined slightly only for persons below 40 years of age. The case-fatality rate was higher in females than in males. The number of hospitalisations and cardiac procedures all rose sharply, and was phenomenal for PTCA (247%). The increase in volume of resource use was starkly greater in private hospitals than in restructured hospitals. The ratios of PTCA to CABG from 1991 to 1996 for private and restructured hospitals showed a greater rate of technology substitution in restructured hospitals than in private hospitals. The average length of stay (LOS, 6.7 days) was fairly constant in restructured hospitals. For private hospitals, LOS declined from 7.6 days in 1991 to 5.6 in 1996. LOS varied little among individual restructured hospitals, but widely among private hospitals. The most common method of payment for AMI hospitalisation was Medisave alone (50%), but for CABG surgery, the proportion of payment made through this method was only 12%. Out-of-pocket payments, Medisave, Medishield and private insurance have increased steadily. These data indirectly suggest that primary prevention and medical care interventions might have begun to succeed in reducing the rates of coronary heart disease in Singapore. The sharp increases in cardiac procedures may be explained by changing supply and demand factors for care of AMI and chronic ischaemic heart disease, including consumer preference for cardiac procedures, overuse of medical intervention, and technological change. More studies are needed to test these hypotheses.

Adult↗
PubMed1998

Benefit of early sustained reperfusion in patients with prior myocardial infarction (the GUSTO-I trial). Global Utilization of Streptokinase and TPA for occluded arteries.

The primary objective of this study was to characterize a large cohort of patients receiving thrombolytic therapy for acute myocardial infarction with respect to the group with a prior event. Patients were randomly assigned to 1 of 4 thrombolytic strategies. Baseline characteristics, 30-day outcomes, and 1-year mortality were compared between patients with (n = 6,704) and without (n = 34,143) prior myocardial infarction. Patients with prior myocardial infarction presented to the hospital earlier than those having their first event, but institution of thrombolytic therapy was delayed. Mortality at 30 days (11.7% vs 5.9%, p = 0.001) and 1 year (17.3% vs 8.2%, p < 0.001) was greater among patients with prior infarction, and independent of other demographic variables. Accelerated alteplase was more effective than streptokinase or combination therapy (30-day mortality 10.4% vs 12.2%, p = 0.012; 1-year mortality 15.9% vs 17.8%, p = 0.041). Infarct vessel patency did not differ between those with and without prior myocardial infarction (67.3% vs 67% at 90 minutes, p = 0.92); however, recurrent ischemia was more common in patients with prior myocardial infarction. Patients with healed myocardial infarction should be educated to ensure early hospital admission if they develop symptoms suggestive of acute infarction, and upon hospital arrival should be promptly triaged to receive reperfusion therapy with accelerated alteplase.

Aged↗
PubMed1998

Heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is being encountered more frequently in patients with cardiovascular disease as use of anticoagulant therapy becomes more widespread. Our understanding of the pathophysiology of this immune-mediated condition has improved in recent years, with heparin-platelet factor 4 complex as the culprit antigen in most patients. New sensitive laboratory assays for the pathogenic antibody are now available and should permit an earlier, more reliable diagnosis, but their optimal application remains to be defined. For patients in whom HIT is diagnosed, immediate discontinuation of heparin infusions and elimination of heparin from all flushes and ports are mandatory. Further management of patients with HIT is problematic at present, as there are no readily available alternative anticoagulant agents in the United States with proven efficacy in acute coronary disease. The direct thrombin inhibitors appear to be the most promising alternatives to heparin, when continued use of heparin is contraindicated, and the results of several multicenter trials evaluating their application in patients with HIT are awaited.

Anticoagulants↗