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Biomedical subjects

W K Lo

Publications and source records attributed to W K Lo.

At least 55 records · Page 3Linked to original sources
PubMed1998

Effectiveness of calcium acetate as a phosphate binder in patients undergoing continuous ambulatory peritoneal dialysis.

We compared the effectiveness of calcium acetate as a phosphate binder with that of calcium carbonate by substituting one for the other in patients undergoing continuous ambulatory peritoneal dialysis. Twenty patients who had been receiving calcium carbonate as a phosphate binder were instead given calcium acetate, initially with two thirds of the previous dose of elemental calcium. The calcium acetate dose was adjusted to achieve adequate calcium-phosphate balance; 65.6% of the previous dose of elemental calcium in calcium carbonate was required. Eighteen of the 20 patients completed the 3-month study. There were no significant differences in the pre-study and study levels of serum phosphate (1.81plus minus0.04 [SEM] versus 1.89plus minus0.06 mmol/L), corrected serum calcium (2.54plus minus0.04 versus 2.57plus minus0.03 mmol/L), calcium phosphate product (4.60plus minus0.15 versus 4.87plus minus0.18), serum alkaline phosphatase (64.75plus minus4.17 versus 69.94plus minus3.77 U/L), and serum parathyroid hormone (122plus minus31 versus 124plus minus27 ng/L). Three patients developed a total of five episodes of hypercalcaemia (corrected calcium level greater-than-or-equal2.85 mmol/L) and four other patients developed gastrointestinal upset. Calcium acetate can thus achieve similar phosphate control to calcium carbonate, using 65.6% of the dose of elemental calcium in calcium carbonate; however, its clinical superiority was not demonstrated in this study.

Journal Article↗
PubMed1998

Percutaneous transluminal angioplasty for stenosis of arteriovenous fistulae: a review of local experience.

The stenosis and subsequent thrombosis of the arteriovenous fistulae may lead to a loss of vascular access sites; this a major problem in chronic haemodialysis patients. Percutaneous transluminal angioplasty has been a popular way of correcting such lesions in recent years. We have reviewed patients who underwent this operation from 1993 to 1996 at the Queen Mary Hospital. Among 11 patients who were documented as having arteriovenous fistula stenosis, 60% of lesions were in the anastomotic area while 40% were in the venous limb. All patients had abnormal dialysis blood line pressures corresponding to the actual site of stenosis. The initial success rate of percutaneous transluminal angioplasty in treating the stenotic lesions was 73%. This method is thus a promising form of semi-invasive treatment for symptomatic arteriovenous fistula stenosis.

Journal Article↗
PubMed1997

Actin filament bundles in cortical fiber cells of the rat lens.

The distribution and organization of actin filament bundles were studied in cortical fiber cells of rat lenses at various ages (3 days to 2.5 months old), using thin-section electron microscopy, immunocytochemistry and immunoblotting. Electron microscopy showed that actin bundles were regularly found along cortical fiber cell membranes of the lens at all ages studied. The actin bundles were commonly arranged in three distinct units, one bundle in each fiber cell, located at the intersections where three hexagonal fiber cells meet as seen in cross sections. These actin bundles were approximately 150 nm in diameter and were composed of 7-nm small filaments. They were aligned parallel to the long axis of fiber cells as judged by both cross and longitudinal sections. The outside border of each bundle was always surrounded by a zone of 10-nm intermediate filaments which have the same orientation as that of the actin bundles. In longitudinal sections, elongated actin bundles were always parallel to the cell membranes. A number of individual actin bundles sometimes were found to form a chain with periodic short intervals. In addition, actin bundles were frequently associated with adherens junctions near the intersections and other regions of fiber cell membranes. By immunoelectron microscopy, we demonstrated that these filament bundles indeed contained actins. By rhodamine-phalloidin labelling, we found that labeled actin bundles appeared as large, distinct dots at the corners of hexagonal fiber cells in all ages studied. In addition, non-bundle F-actins were labeled preferentially along the cell membranes of the short sides of hexagonal fiber cells. This resulted in a unique zigzag pattern of actin labeling commonly seen in the cortical fiber cells of a mature rat lens. Finally, we showed that alpha-actinin was associated with the actin bundles in the fiber cells by immunofluorescent double labeling and immunoblotting. It is suggested that this unique arrangement of actin bundles in fiber cells may provide a stabilizing structure for forming a sharp angle at each corner of fiber cells, thereby the hexagonal shape of the cells can be maintained.

Actinin↗
PubMed1997

Resolution of eosinophilic peritonitis with ketotifen.

Eosinophilic peritonitis is frequently observed in patients of all ages started on peritoneal dialysis. Peritoneal effluent may or may not become noticeably turbid, and if an aliquot for white cell count is sampled at all, eosinophils will be seen to predominate. It does not usually cause concern and settles spontaneously, many times even without the clinician noticing. Occasionally, this condition lingers on for months, and a short course of intraperitoneal hydrocortisone has been shown to be effective in clearing up the eosinophilia. We report a patient with steroid-resistant eosinophilic peritonitis and its successful resolution with ketotifen.

Aged↗
PubMed1997

Immunodetection of membrane skeletal protein 4.2 in bovine and chicken eye lenses and erythrocytes.

PURPOSE: Protein 4.2 is a major erythrocyte membrane skeletal protein, playing an important role in maintaining the integrity and stability of the membrane. It is a transglutaminase-like molecule with no enzymatic cross-linking activity. Several protein 4.2-associated proteins (i.e. band 3, ankyrin, and protein 4.1) and transglutaminase activities have been detected in the lens. The purpose of this study is to find out if protein 4.2 is also expressed in lens fiber membranes. METHODS: Western blot analysis of cell membranes isolated from bovine and chicken lens fibers and erythrocytes, and immunocytochemistry of frozen sections of bovine and chicken lens fibers were carried out using two protein 4.2-specific antibodies. These two peptide antibodies have been used to identify two alternatively spliced protein 4.2 isoforms in human erythrocyte membranes: the short (P4.2S, or hP4.2(691)) and the long (P4.2L, or hP4.2(721)) isoforms. RESULTS: Western blot analysis using anti-P4.2(L) antibody demonstrated specific immunoreactive polypeptides in bovine and chicken lens fiber membranes and erythrocyte membranes, co-migrating with hP4.2(721). Immunofluorescence staining of bovine and chicken lenses, using anti-P4.2(L) antibody, revealed specific signals along the cell membranes of cortical fibers. The signals exhibited a unique, patchy pattern along the cortical fiber cell membranes in both cross-sectional and longitudinal views. In cross sections, the labeling of anti-P4.2(L) along the entire cell membranes gave an appearance of a hexagonal shape of fiber cells. CONCLUSIONS: Protein 4.2, or its analogs, is present in the lens fiber membranes. Its specific staining pattern in the lens fibers suggests that it participates in the architecture of the lens fiber cell membranes, and may play a role in the lens mechanics and pathology.

Amino Acid Sequence↗
PubMed1997

Diagnosing cytomegalovirus disease in CMV seropositive renal allograft recipients: a comparison between the detection of CMV DNAemia by polymerase chain reaction and antigenemia by CMV pp65 assay.

The optimal diagnostic test for CMV disease in renal allograft recipients in a locality with a high CMV seropositive rate has not been fully determined. We compared the usefulness of the CMV pp65 antigenemia (CMV-Ag) assay with the detection of DNAemia by a nested polymerase chain reaction (PCR) method in diagnosing CMV disease in 56 renal allograft recipients, of whom 50 (89.2%) were CMV seropositive prior to transplant (tx). Positive CMV-Ag assays were found in 126/281 samples (44.8%) of 27 patients (48.2%) of whom five had seven episodes of CMV disease. The remaining 22 patients were asymptomatic. The symptomatic patients had significantly higher median peak CMV-Ag levels than the asymptomatic patients [800 (160-1380) vs. 5 (1-604) per 2 x 10(5) peripheral blood leukocyte (PBL), p < 0.0001]. One hundred and eight samples were tested by both CMV-Ag and PCR methods. Out of the 108 samples, 89 showed concordant results (37 positive and 52 negative for both tests). Seventeen samples of 11 patients were CMV-Ag negative/PCR positive. Out of these 11 patients, two had CMV disease and the discrepancy in the results was due to blood samples taken after the start of ganciclovir therapy. Falsely negative PCR tests were found in two samples of two patients with positive CMV-Ag assays. With a outoff antigenemia level of 100 per 2 x 10(5) PBL, the sensitivity, specificity, positive and negative predictive values for diagnosing CMV disease were 100, 96, 71.4 and 100%, respectively. On the other hand, CMV DNAemia was detected in many asymptomatic patients, and the PCR test results correlated poorly with the clinical manifestations of the disease. In symptomatic patients undergoing ganciclovir therapy, the quantification of antigenemia level allowed the assessment of treatment efficacy. In addition, positive CMV-Ag assays at the end of therapy were associated with the subsequent relapse of CMV disease in two patients. The high specificity, together with the short processing time of 4 h, make the CMV-Ag assay the test-of-choice for diagnosing CMV disease in a renal transplant population with a predominance of CMV seropositive patients.

Adolescent↗
PubMed1996

Gap junction structures and distribution patterns of immunoreactive connexins 46 and 50 in lens regrowths of Rhesus monkeys.

Gap junction structures and distribution patterns of immunoreactive connexin46 (Cx46) and connexin50 (Cx50) in normal lenses and lens regrowths of rhesus monkeys were studied using electron microscopy and immunofluorescence double-labeling. Lens regrowths were collected from aphakic eyes of young monkeys whose natural lenses had been surgically removed 11-34 months earlier to simulate monocular congenital cataract surgery in human infants. Approximately 90% of the lens regrowths examined was in the form of a doughnut-shaped Soemmerring's ring located behind the iris. The lens regrowth consisted of lens epithelium and lens fibers enclosed within hypertrophied capsular material. The superficial equatorial region usually contained nucleated young fibers of normal appearance. The other regions consisted of many swollen fibers. Gap junctions were readily observed between fiber cells of both normal and swollen configuration in the lens regrowth. In superficial fibers, gap junctions were not associated with cytoskeletal components. In the intermediate and the deeper cortical regions, actin filament bundles were found specifically associated with gap junctions along both of their cytoplasmic surfaces. An immunofluorescence double-labeling study showed that Cx46 and Cx50 were labeled in the same gap junctions in both superficial and deeper cortical fibers of the normal lens. In contrast, in the lens regrowth strong co-labeling of Cx46 and Cx50 was only observed in the superficial fibers. The labeling for Cx50 was very weak or absent in the deeper cortex, whereas the strong labeling for Cx46 persisted throughout the major portion of the deeper cortex. The labeling for Cx46 finally disappeared in the much deeper cortex. This study shows that (1) the same distribution pattern of actin bundle/gap junction association found in normal lenses is seen in the lens regrowth, and (2) the immunoreactive distribution of Cx46 and Cx50 differ in the lens regrowths as compared with those in the normal lenses of rhesus monkeys.

Actins↗
PubMed1996

Optimal treatment and long-term outcome of tuberculous peritonitis complicating continuous ambulatory peritoneal dialysis.

A retrospective study of the treatment and short- and long-term outcomes of tuberculous peritonitis (TBP) complicating continuous ambulatory peritoneal dialysis (CAPD) among our dialysis patients over a 6-year period was performed. Ten cases of TBP complicating CAPD were identified among 601 dialysis patients between January 1988 and December 1994. There were four male and six female patients. The most common clinical features were abdominal pain, fever, and cloudy peritoneal fluid (PDF). Two patients had concurrent bacterial peritonitis. Extraperitoneal tuberculosis was not observed. The majority of the patients showed neutrophil predominance in the PDF. Only one patient had a positive acid-fast bacilli smear of the PDF. The acid-fast bacilli culture of the PDF was positive in all patients. The patients were treated with isoniazid, rifampicin, and pyrazinamide for 9 to 12 months (mean, 11 months). Continuous ambulatory peritoneal dialysis was continued in all patients. Two patients died, one from multiorgan failure at 2 months and the other from sudden cardiac death at 9 months. Two patients were converted to hemodialysis at 3 months. Six patients continued to receive CAPD after completion of the antituberculous treatment. Four of these six patients were still alive 5 years after the TBP. Three patients were still undergoing CAPD with satisfactory ultrafiltration and solute clearance. None of the patients developed relapse of TBP. We concluded that (1) TBP is a rare but important complication of CAPD, (2) removal of the Tenckhoff catheter is not mandatory in the management of TBP complicating CAPD, and (3) long-term continuation of CAPD is possible after TBP.

Antitubercular Agents↗
PubMed1996

A prospective randomized control study of oral nystatin prophylaxis for Candida peritonitis complicating continuous ambulatory peritoneal dialysis.

A prospective randomized study of the prevention of candida peritonitis (CP) in continuous ambulatory peritoneal dialysis patients using oral nystatin given concomitantly with antibiotic therapy was carried out for 2 years. Patients were randomized into two groups. Nystatin tablets 500,000 units four times a day were given to group 1 but not group 2 patients whenever antibiotics were prescribed. There were 199 patients at risk (mean follow-up, 18.0 months) in group 1 and 198 patients at risk (mean follow-up, 16.6 months) in group 2. The peritonitis and antibiotic prescription rates were comparable between the two groups. There were four episodes of CP in four patients in group 1 and 12 episodes in 11 patients in group 2. The probability of CP-free survival at 2 years was higher in group 1 compared with group 2 (0.974 v 0.915; P < 0.05). However, only three (75%) CP episodes in group 1 and six (50%) in group 2 were considered "antibiotics related." The incidence of antibiotics-related CP was 1.39 and 3.19 per 100 peritonitis episodes and 0.66 and 1.43 per 100 antibiotic prescriptions in groups 1 and 2, respectively (P = NS). We conclude that oral nystatin prophylaxis with each antibiotic prescription reduced the rate of CP in patients on continuous ambulatory peritoneal dialysis irrespective of its apparent temporal relationship to antibiotic prescription.

Administration, Oral↗
PubMed1996

Survival of CAPD patients in a center using three two-liter exchanges as standard regime.

Our objectives were to study long-term patient survival and dialysis adequacy of continuous ambulatory peritoneal dialysis (CAPD) patients treated with a standard regime of three 2-L daily exchanges. It was a retrospective analysis of patient survival and cross-sectional analysis of adequacy of dialysis. The setting was a dialysis unit in a tertiary referral center of a teaching hospital. All patients (n = 507) accepted into the CAPD program from 1983 to June 1994, were analyzed for survival. Adequacy of dialysis was analyzed in all existing patients in 1993 to 1994. The overall patient survival was 93%, 71%, and 57% at one, three, and five years, respectively. The three-year survival rate was 40% for diabetics and 78% for nondiabetics. It was 86%, 85%, 64%, and 43% for patients aged < 35, 35-50, 50-65, and over 65 years, respectively. The mean weekly KT/V of 201 existing CAPD patients was 1.76, and creatinine clearance was 57 L/week/1.73 m2. KT/V by dialysis was only 1.57. The age- and disease-adjusted survival in our center was comparable to centers that used standard four 2-L exchange regimes, despite a substantially lower mean KT/V and creatinine clearance (CrCl).

Adolescent↗
PubMed1994

Actin filament bundles are associated with fiber gap junctions in the primate lens.

A unique association between actin filament bundles and gap junctions in cortical fiber cells of human and monkey lenses was studied with thin-section electron microscopy and immunocytochemistry. Thin-section electron microscopy showed that distinct layers of filament bundles (approximately 55 nm thick) were consistently associated with fiber gap junctions (approximately 16 nm thick) from intermediate to deep cortical regions in both species studied. The filament bundle was composed of 6-8 nm microfilaments which lay along both cytoplasmic surfaces of the junction. Fluorescence microscopy revealed a patchy pattern of F-actin labeling along the fiber cell membranes in the intermediate and deep cortical regions of the lens. The size and distribution pattern of F-actin labeling appear to correlate well with those of filament bundles/gap junctions seen in thin-section electron microscopy. By immunoelectron microscopy, the anti-actin antibody was shown to be localized to filament bundles/gap junctions in the intermediate cortical fibers of human lens, indicating that filament bundles are F-actin in nature. The identical filament bundle/gap junction association was not found in other species examined, including rodent, bird and fish, by the same procedure, suggesting that an association between actin bundles and gap junctions has a special functional role in the primate lens. It is proposed that gap junction-associated actin bundles may provide added structural stability for the primate lens.

Actins↗
PubMed1994

Comparison of different measurements of lean body mass in normal individuals and in chronic peritoneal dialysis patients.

To evaluate different methods of measuring lean body mass (LBM) in chronic peritoneal dialysis (CPD) patients, we first made comparisons in seven normal subjects. Seven methods (total body potassium [TBK] counting, bioelectrical impedance with calculations according to Segal and Deurenberg, near-infrared interactance with and without exercise level included as a variable, anthropometric measurements, and creatinine kinetics) were compared with the standard method of underwater weighing (UW) for measuring LBM. Significant correlations with LBM measured by UW (r > 0.938) were found with LBM measured by all other methods. Compared with UW, the best result in normals was found with TBK as it had high r values, small y-intercepts, and slopes of regression lines close to unity in both measurements of LBM and %LBM; in addition, fat-free mass index by TBK best approximated that by UW and TBK had the lowest mean prediction error with UW. In 11 patients on CPD, LBM was measured by all the above methods except UW. Significant correlations of all methods with LBM measured by TBK used as the reference standard were noted (all r > 0.76) in the CPD population. The LBM measured by creatinine kinetics correlated best (by kilograms or percentage of body weight [%BW]) with LBM from TBK compared with the other methods in which values tended to be higher. The fat-free mass index by creatinine output was nearest to the fat-free mass index by TBK. The root mean square prediction error was lowest between LBM by creatinine output and that by TBK. The findings support the concept of measuring creatinine outputs in CPD patients for estimates of LBM as an index of nutritional status as well as for creatinine clearances as an index of adequacy. Total body potassium and creatinine output measurements of LBM reflect the LBM at normal body fluid volumes ("dry weight") and may be better indices of nutrition in dialysis patients than the other techniques, which include excess fluid in the LBM.

Adult↗
PubMed1994

Treatment of fungal peritonitis complicating continuous ambulatory peritoneal dialysis with oral fluconazole: a series of 21 patients.

Twenty-one episodes of fungal peritonitis occurred over 35 months among 290 patients on CAPD, accounting for 6.3% of all peritonitis episodes. Patients with more frequent bacterial peritonitis were at higher risk of developing fungal peritonitis, and 28.6% of cases followed antimicrobial therapy. Candida species accounted for 85.7% of cases. Oral fluconazole was used as initial therapy in all patients, which was followed by catheter removal if peritonitis failed to improve. The cure rate with fluconazole therapy alone without catheter removal was 9.5%. Fluconazole plus catheter removal, the latter necessitated in 85.7% of cases, resulted in a cure rate of 66.7%. The remaining 3 (14.3%) patients responded to intravenous amphotericin given as salvage therapy. Disease-related mortality was 14.3%. Reinsertion of dialysis catheter was attempted in 15 patients and CAPD was successfully resumed in 13 (86.7%). We conclude that oral fluconazole can be safely used as initial therapy in patients with fungal peritonitis complicating CAPD. Although catheter removal was necessary in the majority of patients, this sequential approach resulted in a relatively low prevalence of peritoneal adhesions and subsequent CAPD failure.

Administration, Oral↗
PubMed1994

Delayed recurrent thromboembolism of the allograft kidney.

Renal artery thromboembolism is a rare event in native kidneys and has never been reported to occur in allograft kidney. We report a case of allograft kidney infarction secondary to embolisation from thrombus in the hypogastric artery supplying the allograft on two separate occasions 1 and 2 years after transplant. Anticoagulation therapy alone was given and the patient responded well with partial recovery of renal function.

Adult↗