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Biomedical subjects

C S Lau

Publications and source records attributed to C S Lau.

At least 91 records · Page 5Linked to original sources
PubMed1997

Continued competency: the experience of the California Dental Association.

The California Dental Association has developed a program--Quality Improvement through Lifelong Learning or QUIL3--that enables a dentist to privately and confidentially determine whether he or she meets current clinical practice standards and has the requisite knowledge to practice dentistry competently. Using the concept of continuous quality improvement (CQI), this innovative program was two years in development and attempts to positively and proactively address issues associated with dental performance. QUIL3 is an initial step.

California↗
PubMed1996

Expression of IL-2R, IL-4R, IL-6R on peripheral blood lymphocytes in systemic lupus erythematosus and correlation with disease activity: a prospective study.

AIMS: To study the expression of interleukin-2 receptor (IL-2R), interleukin-4 receptor (IL-4R) and interleukin-6 receptor (IL-6R) on peripheral blood lymphocytes (PBL) in patients with systemic lupus erythematosus (SLE); to correlate the level of expression of these receptors with SLE disease activity. METHODS: Peripheral blood lymphocytes were studied by a high sensitivity flow cytometry technique using monoclonal antibodies directed against CD25 (IL-2R alpha chain), CD122 (IL-2R beta chain), CD124 (IL-4R), and CD126 (IL-6R). SLE disease activity was scored using the SLE Disease Activity Index, C3 and C4 concentrations, anti-dsDNA level, and absolute lymphocyte count. RESULTS: Compared with normal controls, PBL from patients with SLE had a higher percentage of CD25+ cells (median 20.8% v 16.5%) and a lower percentage of CD122+ cells (median 13.1% v 22.4%). The difference in CD122+ cells was greater in the CD122weak population than the CD122strong (natural killer cell) population. The percentages of CD124+ and CD126+ PBLs in patients with SLE and controls were similar. On CD25+ cells, the relative antigenic level of the IL-2R alpha chain was significantly higher in patients with SLE (median 2.01 v 1.81). The relative antigenic levels of CD122+, CD124+ and CD126+ cells were similar in patients and controls. Neither the percentages nor the relative antigenic levels of all of these cytokine receptors were correlated with any of the parameters of disease activity. CONCLUSION: Lymphocyte activation in patients with SLE was evident from the increase in CD25 expression on PBL, with a reciprocal decrease in CD122 expression. As the expression of IL-2R, IL-4R, IL-6R did not correlate with disease activity, it seems that these cytokine/receptor systems do not play a direct role in disease activation in SLE.

Antigens, CD↗
PubMed1996

Dapsone syndrome in cutaneous lupus erythematosus.

Dapsone is increasingly used in the treatment of rheumatic diseases. It is indicated in many inflammatory skin conditions characterized by polymorphonuclear cell infiltration. Minor reactions to the drug are very common, but severe idiosyncratic reactions are rare considering the large number of patients taking this drug worldwide. We describe 2 patients with cutaneous lupus erythematosus who developed severe dapsone reaction after low dose therapy, with a fatal outcome in one. Physicians should be aware of the potentially lethal side effects of dapsone.

Adult↗
PubMed1995

Reduced red blood cell deformability in patients with rheumatoid vasculitis. Improvement after in vitro treatment with dipyridamole.

OBJECTIVE: To assess red blood cell deformability (RCD) in patients with rheumatoid arthritis (RA) without extraarticular manifestations and in RA with vasculitic complications (RV), and to assess whether in vitro dipyridamole improves RCD. METHODS: An improved filtration technique was used to measure RCD in 15 patients with RA, 18 patients with RV, and 20 age- and sex-matched normal control subjects. Washed erythrocytes suspended in buffer, at 5% hematocrit, were filtered through 4.7 mu Nuclepore Hemafil PC membranes. The initial steady-state relative filtration pressure (iRFP) was used as an index to assess RCD. A lower iRFP value reflects increased deformability, a higher value reflects a decrease. For each sample, 2 cell suspensions were prepared, one blank (control) and one containing 5 microM dipyridamole. RESULTS: The mean iRFP values of cells obtained from patients with RV were significantly higher than those of cells obtained from normal controls. There were no appreciable differences in iRFP between RA patients and normal controls. When the erythrocytes were pretreated in vitro with 5 microM dipyridamole before filtration, their deformability improved markedly (iRFP values were reduced) in all study subjects, compared with untreated cells. CONCLUSION: RCD is reduced in patients with RV, and treatment with dipyridamole may be beneficial if reduced RCD contributes to impaired microvascular perfusion.

Adult↗
PubMed1995

Transverse myelopathy complicating mixed connective tissue disease.

We report the case of a 46-year-old female patient with transverse myelitis complicating mixed connective tissue disease (MCTD). She responded well to steroid and immunosuppressive therapy. Unlike in systemic lupus erythematosus (SLE), transverse myelopathy in association with MCTD is very rarely described. The mechanisms, diagnosis and treatment of transverse myelitis in MCTD are briefly discussed.

Azathioprine↗
PubMed1995

Primary nocardial meningitis in systemic lupus erythematosus.

Nocardia is an important but often overlooked opportunistic infection agent in immunocompromised hosts. Nocardiosis is primarily pulmonary; central nervous system involvement, usually in the form of brain abscess, is less common. Primary nocardial meningitis without associated brain abscess and pulmonary lesion is extremely rare and poses a formidable diagnostic challenge. We report on a patient with systemic lupus erythematosus who presented with a clinical picture of chronic meningitis which failed to respond to empirical antibiotic treatment. She deteriorated and succumbed. Post-mortem examination showed nocardial meningitis without associated brain abscesses. Nocardial meningitis should be considered a differential diagnosis of subacute meningitis in immunocompromised hosts.

Adult↗
PubMed1995

Oral iloprost as a treatment for Raynaud's syndrome: a double blind multicentre placebo controlled study.

OBJECTIVE: To compare the efficacy, tolerance and safety of 50-150 micrograms orally administered iloprost given twice a day versus placebo in patients with Raynaud's syndrome. METHODS: The study was multicentre (n = 3), double blind and placebo controlled. Sixty three patients who had eight or more vasospastic attacks per week were enrolled. After a one week run-in period, all patients received either iloprost or placebo treatment to a maximum tolerated dose of 150 micrograms twice a day for 10 days. Diary cards assessed the duration and severity of the vasospastic attacks. Side effects were monitored by direct questioning. A global assessment of treatment efficacy was made by the patient at the end of treatment and two weeks later. RESULTS: Patient opinion tended to favour iloprost at the end of the 10 day treatment phase (p = 0.09) and this was significant at day 24 (the follow up visit) (p = 0.011). Although the duration and severity of attacks tended to decrease in the iloprost treated group, these results tended not to reach statistical significance (for severity p = 0.06 at end of treatment, p = 0.09 on day 24). CONCLUSION: Iloprost administered intravenously has been shown to be of benefit in the treatment of the Raynaud's syndrome associated with systemic sclerosis, but this route of administration is inconvenient. This study evaluated the use of iloprost administered orally to patients with Raynaud's syndrome. Patient documented improvement was significantly improved by iloprost. Diary card analysis showed a trend in favour of iloprost, but these results did not reach statistical significance.

Administration, Oral↗
PubMed1995

Digital blood flow response to body warming, cooling, and rewarming in patients with Raynaud's phenomenon.

Although the diagnosis of Raynaud's phenomenon (RP) is usually made easily from a careful history, the assessment of RP severity is difficult, for the vasopastic attacks are not easily induced under experimental conditions. In this study, the laser Doppler flowmetry (LDF) technique was used to quantify digital blood flow, which was standardized by body cooling and warming in patients with RP. Twenty-one healthy subjects and 56 RP patients were studied: 7 had primary RP, 22 had suspected secondary Raynaud's syndrome (susp RS), and 27 had systemic sclerosis (SSc)-associated secondary Raynaud's syndrome (SSc RS). The inherent variability in the acral cutaneous circulation was minimized by whole-body warming and cooling. Digital blood flow values at environmental temperatures of 40 degrees C, 12 degrees C, and after rewarming, to 40 degrees C were recorded, as was the time taken for blood flow to reach 25%, 50%, and 75% of the full effects of whole-body cooling and rewarming. Patients with primary RP and susp RS had normal blood flow values at ambient temperatures of 40 degrees C, 12 degrees C, and after rewarming to 40 degrees C when compared with controls, but they had significantly faster vasoconstrictor responses to whole-body cooling, suggesting a heightened sympathetic activity. Additionally, they had slower vasodilator responses with longer 25%max response time to whole-body rewarming. Patients with SSc RS had significantly lower blood flow values at 40 degrees C after initial warming and following subsequent rewarming, and despite a normal vasoconstrictor response to cooling, it took longer for them to vasodilate during rewarming, suggesting that poor digital blood flow in these patients may be more related to digital vasculature abnormalities and not an increase in sympathetic activity. In conclusion, our assessment technique can be used to quantify digital blood flow in patients with RP and may be potentially useful in the investigation of the etiologic role of the sympathetic nervous system in RP.

Adult↗
PubMed1994

CD5-positive and CD5-negative plaque-forming cells against poly-L-lysine-treated sheep erythrocytes in patients with systemic lupus erythematosus.

While attempting to evaluate CD5+ and CD5- anti-DNA-secreting plaque-forming cells (PFC) in patients with systemic lupus erythematosus (SLE), significant numbers of PFC against control sheep erythrocytes (ShE) treated with poly-L-lysine (PLL) but not further conjugated with single-stranded (ss) or double-stranded (ds) DNA were noted. Numbers of PFC obtained using PLL-ShE, ssDNA-ShE and dsDNA-ShE were not significantly different, all reactivity to DNA apparently being accounted for by binding of antibodies to PLL-treated ShE. Nevertheless, anti-PLL-PFC could be inhibited by soluble dsDNA included in the plaque assay. These findings might be explained by cationic anti-DNA antibodies binding non-specifically to anionic PLL. Control healthy subjects gave few PFC against PLL-ShE, ssDNA-ShE or dsDNA-ShE. Anti-PLL-PFC appeared to be related to disease activity, with higher numbers of both CD5+ and CD5- PFC in patients with clinically active SLE.

Adolescent↗
PubMed1993

Effects of fish oil supplementation on non-steroidal anti-inflammatory drug requirement in patients with mild rheumatoid arthritis--a double-blind placebo controlled study.

Maxepa contains eicosapentaenoic acid (EPA) (171 mg/capsule) and docosahexaenoic acid (DHA) (114 mg/capsule). EPA acts as an alternative substrate to arachidonate, leading to the formation of the less proinflammatory prostaglandins ('3' series) and leukotrienes ('5' series). If Maxepa has anti-inflammatory properties it could be expected to reduce the requirement for NSAIDs in patients with RA. This has not been investigated nor has Maxepa therapy been studied over a full 1-yr period. Sixty-four patients with stable RA requiring NSAID therapy only were studied. Patients received either 10 Maxepa or air-filled placebo capsules per day for 12 months. All then received placebo capsules for a further 3 months. Patients were reviewed at 3-monthly intervals. NSAID requirement at entry visit for each patient was assigned as 100%. Patients were instructed to slowly reduce their NSAID dosage providing there was no worsening of their symptoms. Clinical and laboratory parameters of RA activity were also measured. There was a significant reduction in NSAID usage in patients on Maxepa when compared with placebo from month 3 [mean (95% C.I. for mean) requirement--71.1 (55.9-86.2)% and 89.7 (73.7-105.7)%, respectively]. This effect reached its maximum at month 12 [40.6 (24.5-56.6)% and 84.1 (62.7-105.5)%, respectively] and persisted to month 15 [44.7 (27.6-61.8)% and 85.8 (60.5-111.1)%, respectively] (P < 0.001, ANOVA). These patients were able to reduce their NSAID requirement without experiencing any deterioration in the clinical and laboratory parameters of RA activity.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Cicaprost, an orally active prostacyclin analogue: its effects on platelet aggregation and skin blood flow in normal volunteers.

1. Prostacyclin (PGI2) and its analogues may be useful in peripheral vascular disease. However, most have to be given intravenously due to their metabolic instability. 2. We have investigated the pharmacological effects of cicaprost, a synthetic PGI2 analogue which is metabolically stable and bioavailable after oral administration, in eight healthy male volunteers. 3. This was a double-blind, placebo-controlled, cross-over study. The volunteers were given either placebo, 5 micrograms, 7.5 micrograms or 10 micrograms cicaprost (at 09.00 h, 14.00 h, 19.00 h and again at 09.00 h the following day) on four separate occasions each 14 days apart. 4. Platelet aggregation induced by collagen and ADP in platelet rich plasma (PRP) and whole blood were measured prior to and 1 h after the trial medication. Laser Doppler flowmetry measured skin blood flow on the face before and after medication. 5. There was a statistically significant dose relationship in the inhibition of platelet aggregation induced by 2 microM ADP and 0.4 microgram ml-1 collagen in PRP and 2 microM ADP and 0.6 microgram ml-1 collagen in whole blood by cicaprost (P = 0.008, P = 0.34, P = 0.011 and P = 0.036, respectively). The threshold dose was 7.5 micrograms. Attenuation of anti-platelet effects was seen with the 14.00 h and 19.00 h doses. This may be due to a decrease in absorption after meals or to the development of tachyphylaxis. 6. Similar dose dependent effects of cicaprost on skin blood flow were also found (P = 0.01 and P = 0.006 for maximum output signal and red blood cell flux, respectively). The threshold dose was 7.5 micrograms. 7. In conclusion, cicaprost has significant anti-platelet and vasodilatory effects when given in doses of 7.5 micrograms and 10 micrograms three times a day in healthy male volunteers.

Adult↗
PubMed1993

Baseline plasma fibrinolysis and its correlation with clinical manifestations in patients with Raynaud's phenomenon.

OBJECTIVES: (1) To assess if patients with various forms of Raynaud's phenomenon (RP) have abnormal plasma fibrinolysis that may contribute to diminished digital blood flow; (2) to assess whether patients with RP with evidence of endothelial damage have abnormal plasma fibrinolysis; (3) to determine the clinical relevance of abnormalities, if any, in plasma fibrinolysis in patients with RP. METHODS: One hundred and sixty eight patients with significant RP were studied--46 had primary Raynaud's disease (RD), 32 had suspected Raynaud's syndrome secondary to an undifferentiated connective tissue disorder (undifferentiated CTD), 25 had Raynaud's syndrome associated with atherosclerosis (athero RS), and 65 had an underlying connective tissue disease (CTD RS). All attended in the morning after a low fat light breakfast. After a clinical history was obtained, venous blood samples were collected without stasis for assays of plasma fibrinolysis and factor VIII von Willebrand factor antigen (fVIII vWF Ag). Results were compared with those obtained from normal subjects matched for sex and age. As patients with athero RS were significantly older than the other patients with Raynaud's phenomenon, two groups of control subjects were recruited--namely, 'old' and 'young' control subjects. RESULTS: Patients with CTD RS and athero RS had higher concentrations of fVIII vWF Ag (CTD RS median 174.5 range (45-370)% v 100 (38-202)%, p < 0.001; athero RS 182-5 (100-240)% v 100 (50-158)%, p < 0.001). Both had raised fibrinogen (CTD RS 3.25 (1.9-6.8) g/l v 2.4 (1.2-4.2) g/l, p < 0.001; athero RS 3.4 (2.2-6.2) g/l v 2.5 (1.8-3.9) g/l, p < 0.001) and both had diminished fibrinolysis with reduced plasminogen activator activity (CTD RS 79.5 (31-72) mm2 v 92 (37-197) mm2, p < 0.04; athero RS 73 (45-125) mm2 v 98 (41-197) mm2, p < 0.03). Patients with CTD RS also had raised plasminogen activity (3.3 (2.3-5.8) cU/ml v 2.9 (1.5-5.4) cU/ml, p < 0.001). On the contrary, patients with primary RD and undifferentiated CTD had normal fibrinogen and plasma fibrinolysis. Within each patient group, no significant differences in any of the measured variables were found between those who had RP all year and those who had RP in the winter only, those with RP of the hands only and of hands and feet, or those with and without digital ulcers. CONCLUSION: Diminished plasma fibrinolysis is found in patients likely to have endothelial damage (CTD RS and athero RS). These changes are probably a consequence rather than a cause of the disease.

Arteriosclerosis↗
PubMed1993

Abnormal plasma fibrinolysis in patients with rheumatoid arthritis and impaired endothelial fibrinolytic response in those complicated by vasculitis.

OBJECTIVES: (a) To assess plasma fibrinolytic parameters in patients with rheumatoid arthritis (RA) and to determine whether there are differences between patients with RA alone and those with RA complicated by vasculitis. (b) To determine if patients with RA respond differently to venous occlusion compared with normal subjects and to assess whether such a response differs in patients with RA alone and those with rheumatoid vasculitis. (c) To determine the extent of vascular damage in patients with rheumatoid vasculitis and if this correlates with the levels of plasma fibrinolytic parameters. METHODS: Sixty three patients with RA (38 had RA only and 25 had evidence of rheumatoid vasculitis) were recruited. Plasma levels of tissue plasminogen activator antigen (t-PA Ag), plasminogen activator inhibitor (PAI) activity, and factor VIII von Willebrand factor (vWF) were measured before and 10 minutes after venous occlusion. RESULTS: Patients with RA, with or without rheumatoid vasculitis, had higher baseline PAI levels than control subjects. The difference was statistically significant for patients with RA alone but was not statistically significant for patients with rheumatoid vasculitis. After venous occlusion, t-PA Ag levels increased significantly in normal subjects and patients with RA alone, but not in patients with rheumatoid vasculitis. Plasma levels of vWF were significantly higher in patients with rheumatoid vasculitis than in normal subjects and those with RA alone. In patients with RA alone, baseline vWF correlated positively with t-PA Ag levels, whereas a negative correlation was found between these two parameters in patients with rheumatoid vasculitis. A negative correlation between vWF and t-PA Ag levels after venous occlusion was also found in patients with rheumatoid vasculitis. CONCLUSIONS: Patients with rheumatoid vasculitis showed evidence of vascular damage with increased levels of vWF and impaired t-PA Ag release after venous occlusion, a useful measurement of endothelial reserve to remove fibrin. This may be of pathophysiological importance in the development of vasculitis in these patients.

Adult↗