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Biomedical subjects

K M Chow

Publications and source records attributed to K M Chow.

53 records · Page 3Linked to original sources
PubMed2001

Reversible renal failure in paroxysmal nocturnal hemoglobinuria.

A Chinese patient with paroxysmal nocturnal hemoglobinuria (PNH) developed acute nonoliguric renal failure with intercurrent urinary tract infection and hemolysis. There was no evidence of renal vein thrombosis. Renal biopsy showed features of acute tubular necrosis (ATN) and hemosiderosis. Magnetic resonance imaging (MRI) showed characteristic features of renal hemosiderosis. The patient was stabilized with temporary hemodialysis and intravenous fluid. The renal function fully recovered 3 weeks later. We review the literature and summarize the clinical features of this disease entity. To our knowledge, this case is the first to report such disorder with thorough investigation including concomitant diagnostic MRI imaging and renal biopsy.

Acute Kidney Injury↗
PubMed2001

Contribution of gene polymorphisms in the renin-angiotensin system to macroangiopathy in patients with diabetic nephropathy.

The renin-angiotensin system is important in the control of hemodynamic status and pathogenesis of macrovascular disease, which is a major cause of morbidity and mortality in patients with type 2 diabetes with nephropathy. Serum angiotensin-converting enzyme (ACE) and angiotensinogen (Atg) levels are related to their respective gene polymorphisms. Seventy patients with type 2 diabetes with overt nephropathy (serum creatinine >/= 1.5 mg/dL) were studied. Serum ACE activity was measured by the spectrophotometric method. ACE deletion/insertion (D/I) and Atg M235T genotypes were determined by polymerase chain reaction. Patients with and without macroangiopathy were compared. Those with macroangiopathy had increased ACE activity (median, 60.9 U/L; range, 37.9 to 100 U/L versus without macroangiopathy, 47.9 U/L; range, 11.2 to 84.5 U/L; P = 0.01) and prevalence of ACE DD/DI genotypes (DD/DI:II: with macroangiopathy, 61%:39% versus without macroangiopathy, 34%:66%; P = 0.03). Multivariate analysis using age; sex; duration of diabetes; glycemic, blood pressure, and lipid level control; serum creatinine level; and presence of the ACE D allele showed that presence of the D allele (P = 0.03; odds ratio, 1.8; confidence interval, 1.1 to 3.1) and serum creatinine level (P = 0.0007) were independent risk factors for macroangiopathy. Association of the D allele became insignificant after serum ACE activity was included in the analysis in which only serum ACE activity (P = 0.004) and serum creatinine level (P = 0.01) were independent risk factors. Neither Atg M235T nor its synergistic effect with the ACE D allele showed an association with macroangiopathy. In conclusion, the ACE D allele is associated with macroangiopathy in Chinese patients with type 2 diabetes with nephropathy. The association is dependent on its effect on serum ACE activity, which is an independent risk factor for the development of macroangiopathy.

Aged↗
PubMed2001

Rapid recurrence of ANCA-negative pauci-immune vasculitis after cadaveric renal transplantation.

We report a patient with renal failure secondary to antineutrophil cytoplasmic autoantibody (ANCA)-negative pauci-immune systemic vasculitis who developed rapid recurrence of vasculitis involving skin, eye, and kidney allograft 1 month after cadaveric renal transplant while being maintained on cyclosporine, mycophenolate mofetil, and prednisolone. Despite early institution of aggressive treatment with plasma exchange, the disease remained uncontrolled and resulted in substantial morbidity and subsequent graft failure within 1 year post-transplantation. This case confirms that ANCA-negative vasculitides may recur in transplanted patients taking mycophenolate mofetil. Transplantation is contraindicated when active disease is evident.

Adult↗
PubMed2001

Nonconvulsive status epilepticus in peritoneal dialysis patients.

This report describes nonconvulsive status epilepticus (NCSE) in four patients with end-stage renal disease (ESRD) on peritoneal dialysis therapy. All patients presented with acute confusion or stuporous state without clinical motor seizures. Three patients had active systemic infections and were being administered antibiotics. Diagnoses were confirmed in all cases by electroencephalogram (EEG), which showed characteristic diffuse sharp waves and spikes. The EEG appearance improved after anticonvulsant therapy. All patients had satisfactory control of their electrical seizure activity and made varying degrees of mental recovery. To our knowledge, this is the first reported series of NCSE in patients with ESRD on peritoneal dialysis therapy. It shows NCSE as a differential diagnosis for acute confusion. We emphasize the need for nephrologists to consider NCSE as a differential diagnosis for uremic encephalopathy.

Aged↗
PubMed2001

Recurrent IgA nephropathy in renal transplant allografts.

Previous reports of renal transplantation for patients with underlying immunoglobulin A (IgA) nephropathy suggested a recurrence rate greater than 50% for transplant IgA nephropathy. Initially regarded as a benign condition, more recent data showed that recurrent transplant IgA nephropathy may be a significant contributor to graft loss. We performed a retrospective analysis in a single center of 48 kidney transplant recipients, all of Chinese origin, with biopsy-proven IgA nephropathy as the cause of end-stage renal failure to determine the recurrence rate of IgA nephropathy in the transplant allograft and subsequent clinical course in Chinese patients. Median duration of follow-up was 52 months (range, 18 to 155 months). Fourteen patients (29%) had biopsy-confirmed recurrent transplant IgA nephropathy after a median of 52 months (interquartile range, 23 to 82 months) posttransplantation. Recurrent transplant IgA nephropathy was associated with greater serum IgA levels (P = 0.01). The presence of HLA-A2 in transplant recipients (P = 0.002) appeared to protect them from developing recurrent IgA nephropathy in the transplant allograft. Twenty-nine percent of patients with recurrent transplant IgA nephropathy had progressive deterioration of graft function. The progressive graft dysfunction (GD) rate was greater in patients with a transplant from a living related donor (LRD; 21%) compared with those with a transplant from a cadaveric or living unrelated donor (URD; 3%; P = 0.062). Although the cumulative graft survival rate was 100% at 5 years for transplants from both LRDs and URDs, the 10-year graft survival rate was only 63% for a graft from an LRD versus 93% for a URD (log-rank test, P = 0.19). A review of other reported series of recurrent transplant IgA nephropathy also showed an apparently greater incidence of GD for a graft from an LRD (28%) compared with a URD (15%). Our data suggest that although recurrent transplant IgA nephropathy is highly prevalent among the Chinese population, the risk for disease recurrence is not particularly increased compared with other ethnic groups. The trend toward a greater risk for GD for living related compared with unrelated allografts in patients with IgA nephropathy needs to be confirmed with further prospective study.

Adult↗
PubMed2001

Severe bone marrow failure associated with the use of alternating steroid with chlorambucil in lupus membranous nephropathy in Chinese.

Severe pancytopenia associated with the use of alternating steroid with chlorambucil regimen was described in six patients with nephrotic syndrome secondary to lupus membranous nephropathy (WHO class V). We believe this is the first report describing the life-threatening degree of marrow toxicity associated with this regimen of alternating steroid with chlorambucil in a Chinese population. Our data suggests that the susceptibility to marrow toxicity with the use of chlorambucil may only be applicable to Chinese patients with underlying systemic lupus erythematosus as a similar degree of toxicity has neither been reported in lupus patients of other ethnic groups nor in non-lupus patients of Chinese origin.

Adult↗
PubMed2001

Cuffed-tunneled femoral catheter for long-term hemodialysis.

BACKGROUND: Hemodialysis access is a challenging problem in patients with exhausted dialysis access sites of their upper extremities. Femoral arterio-venous polytetrafluoroethylene (PTFE) graft is often necessary. The safety and efficacy of cuffed tunneled catheters at the femoral site for long-term hemodialysis has not been extensively studied. METHODS: We inserted 14 cuffed-tunneled femoral catheters in 11 hemodialysis patients with exhausted dialysis access sites of their upper extremities. Access survival and risk of infection were compared with the 11 femoral PTFE grafts in 10 patients of our center during the same period. The choice of dialysis access was determined by the individual nephrologist. Access survival was defined as the achievement of a blood flow rate of at least 180 ml/min. RESULTS: The median survival of tunneled femoral catheter and PTFE graft were 166 days and 560 days respectively (log-rank test, p = 0.33). Seven of the 14 tunneled femoral catheter remained in use 3 months after insertion. The incidence of catheter- or graft-related infection was 0.38 and 0.23 episodes per 100 catheter/graft days for tunneled femoral catheters and PTFE graft respectively (p = 0.6). Five tunneled catheters and one PTFE graft had to be removed because of infection. Blood flow rates achieved were comparable between tunneled femoral catheter and PTFE graft. CONCLUSIONS: Our preliminary data suggest that the cuffed tunneled femoral catheter has reasonable access survival and an acceptable risk of infection. It may provide a safe and effective access for long-term hemodialysis patients with exhausted access in their upper extremities, especially high risk patients who are not suitable for femoral PTFE graft creation.

Catheters, Indwelling↗
PubMed2001

The cost barrier to peritoneal dialysis in the developing world--an Asian perspective.

Countries in Asia vary significantly in culture and socioeconomic status. Dialysis costs and reimbursement structures are significant factors in decisions about the rates and modalities of renal replacement therapy. From our survey of Asian nephrologists conducted in 2001, a number of observations can be made. In many developing countries, the annual cost of continuous ambulatory peritoneal dialysis (CAPD) is greater than the per-capita gross national income (GNI). The median cost of a 2-L bag of peritoneal dialysis (PD) fluid is around US$5. The absolute cost of PD fluid among countries with significant differences in per-capita GNI actually varies very little. Thus, most renal failure patients can be expected to have problems accessing PD therapy in developing countries in Asia. In countries with unequal reimbursement policies for PD versus hemodialysis, a lack of incentive to prescribe PD also exists. Automated PD is nearly non existent in many developing countries in Asia. Some possible ways to reduce the cost barriers to PD in those countries include individual governments providing more public funding for treating dialysis patients; dialysate-producing companies reducing the cost of their products; physicians using appropriately smaller exchange volumes (3 x 2 L) in some Asian patients with smaller body sizes and with residual renal function; and reducing the complication rate for PD (for example, peritonitis) thereby reducing the costs required for treatment and hospitalization.

Asia, Western↗
PubMed2000

Studies on the subsite specificity of rat nardilysin (N-arginine dibasic convertase).

The subsite specificity of rat nardilysin was investigated using fluorogenic substrates of the type 2-aminobenzoyl-GGX(1)X(2)RKX(3)GQ-ethylenediamine-2,4- dinitrophenyl, where P(2), P(2)', and P(3) residues were varied. (The nomenclature of Schechter and Berger (Schechter, I., and Berger, A. (1967) Biochem. Biophys. Res. Commun. 27, 157-162) is used where cleavage of a peptide occurs between the P(1) and P(1)' residues, and adjacent residues are designated P(2), P(3), P(2)', P(3)', etc.) There was little effect on K(m) among different residues at any of these positions. In contrast, residues at each position affected k(cat), with P(2) residues having the greatest effect. The S(3), S(2), and S(2)' subsites differed in their amino acid preference. Tryptophan and serine, which produced poor substrates at the P(2) position, were among the best P(2)' residues. The specificity at P(3) was generally opposite that of P(2). Residues at P(2), and to a lesser extent at P(3), influenced the cleavage site. At the P(2) position, His, Phe, Tyr, Asn, or Trp produced cleavage at the amino side of the first basic residue. In contrast, a P(2) Ile or Val produced cleavage between the dibasic pair. Other residues produced intermediate effects. The pH dependence for substrate binding showed that the enzyme prefers to bind a protonated histidine. A comparison of the effect of arginine or lysine at the P(1)' or P(1) position showed that there is a tendency to cleave on the amino side of arginine and that this cleavage produces the highest k(cat) values.

Amino Acids↗
PubMed2000

Women with placenta praevia and antepartum haemorrhage have a worse outcome than those who do not bleed before delivery.

We set out to assess the maternal and neonatal outcomes of women with placenta praevia and antepartum haemorrhage (APH) between 1991 and 1997, compared with woman with a diagnosed placenta praevia who did not bleed. The demographic data, maternal and perinatal outcomes of 159 women with antepartum haemorrhage were compared with 93 women without antepartum haemorrhage in a retrospective study. Women with antepartum haemorrhage had the diagnosis of placenta praevia confirmed at an earlier gestation. More women with antepartum haemorrhage received antenatal steroids and tocolytic agents, and had emergency caesarean sections. The majority of women with bleeding had an emergency caesarean section for antepartum haemorrhage and more delivered early because of fetal distress. There were more preterm deliveries in women with antepartum haemorrhage. The mean birth weight was 2.69 kg in the women with antepartum haemorrhage and 3.06 kg in those without. More infants in the bleeding group had a low Apgar score at the first minute, respiratory distress syndrome, and admission to special baby care and neonatal intensive care unit. It is concluded that there is an increased risk of premature delivery in women with antepartum haemorrhage and placenta praevia. Aggressive management, tocolysis and cervical cerclage should be explored further to improve the perinatal outcome. Women without antepartum haemorrhage can be managed on an outpatient basis.

Journal Article↗
PubMed2000

Group B streptococcal meningitis in adults: recent increase in Southeast Asia.

BACKGROUND: Meningitis caused by Streptococcus agalactiae (Group B Streptococcus) is rare in adults and usually affects patients with predisposing conditions. AIMS: To describe an increase in adult group B streptococcal meningitis occurring in parallel in Hong Kong and Singapore. METHODS: All cases of bacterial meningitis admitted to the Prince of Wales Hospital, Hong Kong and Singapore General Hospital in 1998, aged 15 years or above, were reviewed. Medical records for the previous ten years were searched for previous cases of adult group B streptococcal meningitis. RESULTS: In 1998, 29 adult patients with bacterial meningitis were admitted to the two hospitals. S. agalactiae was isolated in 11 cases, Streptococcus pneumoniae in three cases, Klebsiella pneumoniae in two cases, and Pseudomonas pseudomallei in one case. In 11 cases no bacteriological diagnosis could be made. Two patients with adult group B streptococcal meningitis had predisposing conditions for infection. One patient died before a definite diagnosis could be established. A ten year review of records revealed one previous case of adult group B streptococcal meningitis in a patient with multiple risk factors. CONCLUSIONS: An increase of group B streptococcal meningitis has occurred among adults admitted to two major hospitals in two Southeast Asian cities. In the majority of cases there were no identifiable predisposing conditions. The cause of this increase of group B streptococcal remains unclear.

Adult↗
PubMed2000

Vascular endothelial growth pattern of endochondral bone graft in the presence of demineralized intramembranous bone matrix--quantitative analysis.

OBJECTIVE: To determine the timely ingrowth of new blood vessels of composite endochondral (EC) bone and demineralized bone matrix (DBM) prepared from intramembranous (IM) origin (EC-DBM(IM)) and to compare it with EC bone graft alone. DESIGN: Thirty-two rabbits with 32 critical-size (10 x 5 mm), full-thickness bony defects in rabbit parietal bone were divided into two groups: composite EC-DBM(IM) group-implanted with composite autogenous EC bone and DBM(IM); EC bone group-implanted with EC bone alone. Two rabbits from each group were sacrificed-1, 2, 3, 4, 5, 6, 7, and 14 days after grafting. Neovascularization was assessed by immunohistochemical staining with antihuman angiogenesis-related endothelial cell antibodies (EN 7/44). Quantitative analysis of neovascularization, represented by percentage area of positive immunohistochemical staining, was performed on 320 sections of the experimental groups by a computer-assisted image analyzer. RESULTS: Positive immunohistochemical staining was first identified on day 2 post grafting for the composite EC-DBM(IM) group in comparison with day 4 in the EC bone graft group. The composite EC-DBM(IM) bone graft group showed earlier and almost 100% more neovascularization when compared with the EC bone graft group. CONCLUSION: DBM(IM) enhances healing and integration of EC bone graft by enhancing vascularization as well as increasing the amount of new blood vessels formed. In clinical cases in which EC autogenous bone is used to graft a large defect such as in cleft palate and craniofacial surgery, DBM(IM) should allow better integration and healing of the EC bone graft to the host bone.

Animals↗
PubMed1999

Demineralized intramembranous bone matrix augments the healing of endochondral bone graft.

The aim of this study was to examine the osteogenic potential of demineralized bone matrix prepared from intramembranous bone (DBMIM) and to examine its effects on the healing of endochondral autogenous bone grafts. Twenty-four defects in 24 New Zealand white rabbits were used as experimental groups. Twelve defects were grafted with endochondral bone, and the other 12 defects were grafted with endochondral bone with DBMIM (EC-DBMIM). One rabbit from each group was sacrificed on days 1, 2, 3, 4, 5, 6, and 7 postgrafting, and the remaining 5 rabbits from each group were sacrificed on day 14 postgrafting. Another 8 defects in 4 rabbits were used as control groups: 4 defects were left empty (passive control), and 4 defects were grafted with rabbit skin collagen (positive control). They were all sacrificed at 14 days after grafting. Serial sections were made across the whole defect. Quantitative analysis was performed on 100 sections of the 14-day experimental groups by image analysis. Four hundred fourteen percent more new bone was formed in defects grafted with composite EC-DBMIM than in those grafted with endochondral bone alone (P < 0.0001). No bone was formed in either passive or positive controls. Histologic examination of the bone grafts revealed intermediate-stage cartilage, and immunohistochemical examination revealed earlier vascularization in the composite EC-DBMIM groups. In conclusion, DBMIM has extremely high osteoinductive properties and greatly enhances the integration of endochondral bone with defects of intramembranous bone in origin.

Analysis of Variance↗
PubMedDate not supplied

Concomitant occurrence of hypodontia and supernumerary teeth in a patient with Down syndrome.

Concomitant hypodontia and supernumeraries in a patient suffering from Down syndrome are presented. Concomitant hypodontia and supernumerary teeth are relatively rare, and this is the first case reported in a patient with Down syndrome. A conservative approach to management will be pursued, with the accent on oral hygiene reinforcement and prevention.

Abnormalities, Multiple↗
PubMedDate not supplied

Pseudo-renal failure following total abdominal hysterectomy.

Intraperitoneal urinary bladder perforation should be in the differential diagnosis of acute oliguric renal failure soon after gynecological surgery. We present a case of reversible acute pseudo-renal failure after total abdominal hysterectomy for uterine fibroid. Biochemical features of uremia occur as a result of intraperitoneal extravasation of urine, which is in turn reabsorbed through the peritoneum. Early recognition and surgical repair, as opposed to dialysis therapy, are warranted in such clinical setting. Nephrologists, who are often the first to encounter those patients with presumably acute renal failure, should be aware of this condition. Prompt recovery of the serum biochemistry is to be expected, in contradistinction to genuine renal failure or kidney insults.

Acute Kidney Injury↗