Comparison of Long-Term Survival (Beyond 12 Years) in Patients on Peritoneal Dialysis and on Hemodialysis

Objective

We investigated the clinical condition and complications of patients on peritoneal dialysis (PD) and on hemodialysis (HD) for more than 12 years.

Design

This retrospective review was carried out in the renal unit of the Tung Wah Hospital, Hong Kong.

Patients and Methods

Of 103 HD and 341 PD patients who started dialysis before 1990, 14 HD and 22 PD patients were dialyzed for more than 12 years. We evaluated basic demography at the 12th year of dialysis and at the most recent follow-up, and assessed the prevalence of cardiovascular disease, bone disease, dialysis-related amyloidosis (DRA), and acquired cystic disease (ACD). Outcomes and mortality were recorded.

Results

The 36 patients in the study included 22 women and 14 men. The PD patients were older ( p = 0.021) and had lower levels of serum phosphate and calcium × phosphate product. Only 3 patients were diabetic. Cardiovascular disease was present in 30 patients (83.3%), the most common types being ischemic heart disease (IHD, n = 11) and left ventricular hypertrophy (LVH, n = 22). Symptomatic DRA was found in 13 patients (36.1%), more commonly in the HD group ( p = 0.014). Bone disease was present in 32 patients (88.9%), with parathyroidectomy being more frequently performed in the PD patients ( p = 0.048). Symptomatic ACD occurred in 5 patients (13.9%). At the most recent follow-up, 26 patients were still on dialysis, 3 patients had undergone renal transplantation, and 7 patients had died, the causes of death being sudden death ( n = 3), cerebrovascular accident ( n = 1), chest infection ( n = 2), and peritonitis ( n = 1). Patient survival was similar in the PD and HD groups. Age at commencement of dialysis predicted mortality ( p = 0.012), but mode of dialysis, sex, and presence of diabetes mellitus did not.

Conclusions

Long-term survival is possible for both dialysis modalities (PD and HD), particularly for young, non diabetic patients. Symptomatic DRA is less common in PD patients, but the prevalence of other long-term complications is similar for both groups. Cardiovascular-related problems remain the leading cause of death.

A prospective randomized study on three different peritoneal dialysis catheters

OBJECTIVE

We compared outcomes for catheters with different configurations: conventional straight, swan-neck straight tip, and swan-neck curled tip.

DESIGN

The study was conducted as a prospective randomized controlled trial in the continuous ambulatory peritoneal dialysis (CAPD) unit of a university center.

PATIENTS AND METHODS

We randomized 93 new regular CAPD patients without prior peritoneal dialysis (PD) catheter insertion to receive a conventional straight, double-cuffed catheter (CS), a swan-neck straight catheter (SNC), or a swan-neck curled tip catheter (SNC) in 2:1:1 ratio.

RESULTS

The exit-site infection (ESI) rate was slightly lower with swan-neck catheters as compared with straight catheters, but the difference was not statistically significant. The peritonitis rate and overall catheter survival were similar. In Staphylococcus aureus nasal non carriers as compared with carriers, ESI-free catheter survival was significantly better with swan-neck catheters (p = 0.0302 and p = 0.82 respectively). As compared with SC catheters, SNC catheters had a significantly higher migration rate (p = 0.022).

CONCLUSIONS

Swan-neck catheters were associated with a slightly better ESI rate, but SNC catheters are not routinely recommended because of a high migration rate. The SNS catheter is therefore recommended as the first-line catheter of choice, particularly in populations with a low rate of S. aureus nasal carriage.

Comparison of long-term survival (beyond 12 years) in patients on peritoneal dialysis and on hemodialysis

OBJECTIVE

We investigated the clinical condition and complications of patients on peritoneal dialysis (PD) and on hemodialysis (HD) for more than 12 years.

DESIGN

This retrospective review was carried out in the renal unit of the Tung Wah Hospital, Hong Kong.

PATIENTS AND METHODS

Of 103 HD and 341 PD patients who started dialysis before 1990, 14 HD and 22 PD patients were dialyzed for more than 12 years. We evaluated basic demography at the 12th year of dialysis and at the most recent follow-up, and assessed the prevalence of cardiovascular disease, bone disease, dialysis-related amyloidosis (DRA), and acquired cystic disease (ACD). Outcomes and mortality were recorded.

RESULTS

The 36 patients in the study included 22 women and 14 men. The PD patients were older (p = 0.021) and had lower levels of serum phosphate and calcium x phosphate product. Only 3 patients were diabetic. Cardiovascular disease was present in 30 patients (83.3%), the most common types being ischemic heart disease (IHD, n = 11) and left ventricular hypertrophy (LVH, n = 22). Symptomatic DRA was found in 13 patients (36.1%), more commonly in the HD group (p = 0.014). Bone disease was present in 32 patients (88.9%), with parathyroidectomy being more frequently performed in the PD patients (p = 0.048). Symptomatic ACD occurred in 5 patients (13.9%). At the most recent follow-up, 26 patients were still on dialysis, 3 patients had undergone renal transplantation, and 7 patients had died, the causes of death being sudden death (n = 3), cerebrovascular accident (n = 1), chest infection (n = 2), and peritonitis (n = 1). Patient survival was similar in the PD and HD groups. Age at commencement of dialysis predicted mortality (p = 0.012), but mode of dialysis, sex, and presence of diabetes mellitus did not.

CONCLUSIONS

Long-term survival is possible for both dialysis modalities (PD and HD), particularly for young, non diabetic patients. Symptomatic DRA is less common in PD patients, but the prevalence of other long-term complications is similar for both groups. Cardiovascular-related problems remain the leading cause of death.

Screening by trained nurses for peripheral vascular disease in continuous ambulatory peritoneal dialysis patients with and without diabetes

OBJECTIVE

We studied the effectiveness of a screening program for peripheral vascular disease (PVD) carried out by trained renal nurses in patients with and without diabetes on continuous ambulatory peritoneal dialysis (CAPD).

PATIENTS AND METHODS

We recruited 30 stable diabetic and 30 stable non diabetic CAPD patients into this cross-sectional study. Trained renal nurses measured the patients' ankle-to-brachial systolic pressure index (ABI) using a Doppler ultrasound machine and their foot vibration perception (VPT) using a biothesiometer, and administered a questionnaire on foot symptoms. An ABI < 1.0 was regarded as abnormal and suggestive of the presence of PVD. An ABI < 0.7 or > 1.3 was regarded as severely abnormal. Findings for VPT were classified as normal or abnormal. Patients were then followed for 1 year for any overt development of clinical PVD, leg complications, and other vascular complications and for clinical outcome.

RESULTS

The mean age of the patients was 63 +/- 9 years, and the ratio of men to women was 1:1.3. An abnormal ABI was seen in 22 patients (37%). The questionnaire detected clinical PVD symptoms in 3 patients. Abnormal ABI and VPT findings were more frequent in diabetic patients. After 12 months of follow-up, patients with an abnormal ABI (and particularly those with a severely abnormal ABI) were more likely to develop leg complications and any type of cardiovascular disease than were patients with a normal ABI. Foot vibration perception had no predictive value on subsequent development of leg complications. When risk factors including age, ABI, and VPT were analyzed by logistic regression, only ABI was a significant independent predictor of subsequent lower-limb vascular complications [odds ratio (OR): 21.0; 95% confidence interval (CI): 2.35 to 187.0; p = 0.00064]. The OR for moderately abnormal ABI was 13.0 (95% CI: 1.015 to 166.3); for severely abnormal ABI, it was 27.4 (95% CI: 2.35 to 187.0, p = 0.0045).

CONCLUSIONS

Measurement of ABI by Doppler ultrasound is a useful and effective screening test for PVD in CAPD patients. In this study, VPT was not shown to be predicative of future leg complications, indicating that peripheral neuropathy plays a less important role in the development of such complications. Our results proved that trained renal nurses can play an active role in detecting foot problems in renal patients by ABI measurement.

Effect of Kt/V on survival and clinical outcome in CAPD patients in a randomized prospective study

BACKGROUND

There has been a lack of randomized control study on the effect of Kt/V on patient outcome. This interventional study was designed to examine the effect of Kt/V on continuous ambulatory peritoneal dialysis (CAPD) patients' clinical outcome and nutritional status in a randomized prospective manner.

METHOD

A total of 320 new CAPD patients with baseline renal Kt/V <1.0 were recruited from six centers in Hong Kong and were randomized into three Kt/V targets: group A, 1.5 to 1.7; group B, 1.7 to 2.0; and group C,>2.0. Kt/V and nutritional status were assessed every 6 months and dialysis prescription adjusted accordingly. Nutritional assessment included serum albumin and composite nutritional index (CNI). Patients were allowed to withdraw at the discretion of their physicians or themselves.

RESULTS

Total Kt/V were significantly different between groups (P = 0.000) and the difference was contributed by peritoneal Kt/V only. The overall 2-year patient survival was 84.9%. There was no statistical difference in patient survival among the three groups (2-year survival in group A, 87.3%; group B, 86.1%; and group C, 81.5%). However, there were more patients withdrawn by physicians in group A (group A, 16; group B, 7; and group C, 6; P = 0.023). Total Kt/V or Kt did not significantly affect survival after adjustment to age and diabetes. There was no difference in serum albumin, CNI scores, and hospitalization rate, but there were more patients in group A requiring erythropoietin (EPO) treatment after 1 year.

CONCLUSION

Patients with total Kt/V maintained below 1.7 had significantly more clinical problems and severe anemia but there was no difference in outcome demonstrated for patients with Kt/V maintained above 2.0 and between 1.7 and 2.0. We recommended that the minimal target of total Kt/V should be above 1.7.

Analgesic efficacy of continuous delivery of bupivacaine by an elastomeric balloon infusor after abdominal hysterectomy: a prospective randomised controlled trial

OBJECTIVE

To investigate the analgesic efficacy and morphine-sparing effect of continuous bupivacaine wound infiltration after abdominal hysterectomy.

DESIGN

Prospective, randomised controlled trial.

SAMPLE

Fifty-two female ASA I or II patients were enrolled with 26 patients in each of the study and control groups.

METHODS

The study group received 0.5% bupivacaine infusion into the incisional (Pfannenstiel) wound via an elastomeric infusor at 2 mL/hr for 48 hours postoperatively plus morphine via a patient controlled analgesia (PCA) pump. The control group had only PCA morphine.

RESULTS

There were no significant differences in the visual analogue scores (VAS) for pain nor PCA morphine usage for 48 hours postoperatively

CONCLUSION

That continuous infusion of the incisional wound with 0.5% bupivacaine did not confer additional analgesia over PCA morphine after abdominal hysterectomy

Reactivation of systemic lupus erythematosus in a dialysis patient after tuberculous peritonitis

The disease activity of patients suffering from lupus nephritis usually becomes quiescent after the onset of end stage renal failure. Reactivation of lupus activity, especially after a long period of dialysis, is uncommon. Factors that might trigger off lupus reactivation after dialysis have not been well defined. We report a case of a 43-year-old Chinese woman on long-term peritoneal dialysis, who developed lupus reactivation with cerebral involvement 2 weeks after she was diagnosed to have tuberculous peritonitis. The close temporal relationship between the tuberculous peritonitis and the lupus reactivation raise the possibility that the tuberculous infection might have triggered off the lupus reactivation.

A retrospective survey of attitudes toward acceptance of peritoneal dialysis in Chinese end-stage renal failure patients in Hong Kong--from a cultural point of view

OBJECTIVE

We undertook to study the attitudes toward dialysis of patients approaching end-stage renal failure and to analyze those attitudes from a cultural perspective.

SETTING

The study was performed in the pre-dialysis clinic of a tertiary referral renal center.

PATIENTS

All patients of Chinese ethnic origin seen in the pre-dialysis clinic from 1995 to 2000 for assessment of dialysis therapy were included.

METHOD

We performed a retrospective analysis of patient records with regard to attitudes of the patients toward dialysis, reasons for those attitudes, and factors that could lead to a subsequent change in attitude.

RESULTS

We assessed 462 patients over the 6-year period. Their mean age was 65.5 +/- 13.3 years, and 43.9% of the patients had diabetes. Peritoneal dialysis (PD) was offered to 74% of the patients, and hemodialysis (HD) to 3.9%. Among the patients offered PD, only 44% accepted dialysis. After counselling, 54% of the patients who originally declined PD ultimately accepted it. The major reasons for refusing PD were the ideas of "having lived long enough" and "lack of family support." Most other reasons could be overcome by counselling. Only a minority of patients demanded hemodialysis.

CONCLUSIONS

Declining an offer of dialysis was common. Counselling helped patients to accept PD. Certain cultural elements that hindered acceptance of dialysis were involved in the ideas of "having lived long enough" and "lack of family support." Those cultural elements should be tackled more specifically during counselling.

Expression of apoptotic regulators and their significance in cervical cancer

Insufficient apoptosis is implicated in many human cancers, including cervical carcinoma. The objectives of this study were to explore changes of apoptosis-regulating gene expression and their clinical significance in cervical cancer. The expression of apoptosis-regulating genes, including five Bcl-2 family and two caspase family members, was evaluated in 43 cervical invasive squamous cell carcinomas, using immunohistochemistry. Specimens in which >or=10% of the neoplastic cells showed cytosolic immunoreactivity were considered to be immunopositive. Results were correlated with clinico-pathologic characteristics of the subjects. All seven apoptotic regulators examined were positive in a proportion of the tumors. The percentage of cases expressing Bax was higher in the patients without evidence of disease after treatment than in the patients alive with disease or who died of disease (P<0.05). A significant difference in disease-free survival was detected between Bax-positive and -negative groups (P<0.05), and in overall survival between Mcl-1-positive and -negative groups (P<0.05). Significant association between the seven markers tested was only found for caspase 3 and Bak immunoreactivity in cervical carcinoma (P<0.05). The results demonstrate expression of multiple apoptosis-modulating proteins in cervical cancer. There appears to be complex regulation of apoptosis protein levels in association with clinical behavior of cervical squamous cell carcinoma.

What factors contribute to differences in the practice of peritoneal dialysis between Asian countries and the West?

To study variations in the practice of peritoneal dialysis within Asia and between Asia and the West, relevant information was collected through questionnaires from nephrologists in several Asian countries and by a literature search. Data indicate that economy significantly affects dialysis treatment rates. Peritoneal dialysis was often underutilized. The effect of Kt/V on survival was less obvious compared to the West in countries where peritoneal dialysis patient survival rates were high. More cost-effective dialysis regimes should be developed to increase dialysis treatment rates.

Bispectral index in assessment of adequacy of general anaesthesia for lower segment caesarean section

Awareness among parturients during general anaesthesia for caesarean section, though now uncommon, remains a concern for obstetric anaesthetists. We examined the adequacy of our general anaesthetic technique for avoiding explicit awareness by determining the depth of anaesthesia using Bispectral Index (BIS) monitoring. Twenty ASA1 parturients having general anaesthesia for lower segment caesarean section were studied. The drugs and doses used for each anaesthetic were similar Intraoperative Bispectral Index, haemodynamic parameters, end-tidal isoflurane concentration and inspired nitrous oxide fraction were measured and the postoperative incidence of explicit awareness was assessed. All anaesthetists were blinded to the Bispectral Index value throughout the operation. The depth of anaesthesia at various stages of the operation was evaluated by recording the Bispectral Index. Patients were interviewed for any intraoperative recall or awareness at the end of operation. A median BIS of 70 or below was recorded on most occasions during surgery. The range was 52 to 70, with values reaching 60 and below at intubation, uterine incision and delivery. Haemodynamic stability was satisfactory and there was no case of uterine atony, fetal compromise or postpartum haemorrhage. No patient experienced intraoperative dreams, recall or awareness. Our current general anaesthetic technique appeared inadequate to reliably produce BIS values of less than 60 that are associated with a low risk of awareness. However, no patients experienced explicit awareness.

Tuberculosis infection in Chinese patients undergoing continuous ambulatory peritoneal dialysis

A retrospective study of the prevalence and pattern of tuberculosis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was performed. Thirty-eight cases of tuberculosis were diagnosed among 790 patients (18 men, 20 women; mean age, 58 +/- 12.6 years) between July 1994 and June 2000. The interval between the initiation of CAPD and onset of tuberculosis ranged from 1 to 168 months (median, 22 months). There were 18 cases of pulmonary tuberculosis, 14 cases of tuberculous peritonitis, 5 cases of tuberculous lymphadenitis, and 1 case of tuberculous synovitis. Patients with pulmonary tuberculosis usually presented with fever, constitutional symptoms, and pleural effusion or pulmonary infiltrates on chest radiograph. Abdominal pain and turbid dialysate were the main presenting symptoms in patients with tuberculous peritonitis. Diagnosis was established by positive culture in 20 patients, typical histological characteristics on a tissue biopsy specimen in 10 patients, and response to empirical antituberculous treatment in 8 patients. The duration of symptoms before the diagnosis of tuberculosis and initiation of antituberculous treatment ranged from 7 to 57 days (median, 30 days). Antituberculous treatment consisted of isoniazid, rifampicin, pyrazinamide, and ofloxacin for 9 to 15 months. Antituberculous treatment generally was well tolerated. Twenty-seven patients (71%) completed antituberculous treatment. No recurrence of tuberculosis was observed after a mean follow-up of 19.8 months. Eleven patients (29%) died while on antituberculous treatment; none of the deaths appeared to be directly caused by tuberculosis. We conclude that: (1) tuberculosis is prevalent among CAPD patients in our locality; (2) extrapulmonary tuberculosis, particularly tuberculous peritonitis, is common; and (3) a high index of suspicion for tuberculosis among CAPD patients is warranted to ensure early diagnosis and prompt initiation of treatment.

Progressive demyelinating neuropathy after initiation of continuous ambulatory peritoneal dialysis--report of two cases

We report on two patients who developed rapidly progressive demyelinating neuropathy within 6 to 10 weeks after the initiation of continuous ambulatory peritoneal dialysis. The neuropathy in one patient resolved after kidney transplantation while that of the other patient improved with immunosuppressive therapy. The close temporal relationship between the initiation of peritoneal dialysis and the onset of neuropathy suggests that these two events may be causally related.

Relationship between adequacy of dialysis and nutritional status, and their impact on patient survival on CAPD in Hong Kong

OBJECTIVE

Superior patient survival on continuous ambulatory peritoneal dialysis (CAPD) with 3 x 2-L exchanges has been reported from Hong Kong. This study examined the relationship between indices of dialysis adequacy and nutrition and patient survival on CAPD in Hong Kong.

DESIGN

A cross-sectional study on prevalent CAPD patients. Patients were assessed for indices of dialysis adequacy and nutritional status with a composite nutritional index (CNI). Patients were then followed for 24 months. Survival data were analyzed according to adequacy indices and nutritional status.

SETTING

All prevalent CAPD patients in nine dialysis centers in Hong Kong as of 1 April 1996.

MAIN OUTCOME MEASURE

Mortality.

RESULTS

937 patients were assessed: 68.2% were using 3 x 2-L exchanges per day; mean age was 54.6 +/- 13 years. Mean total Kt/V was 1.83 +/- 0.42 and total creatinine clearance was 55.6 +/- 19.5 L/week/1.73 m2. 19% of patients were moderately to severely malnourished according to the CNI. There was no significant correlation between indices of adequacy and serum albumin or CNI. The 1- and 2-year patient survival from the time of assessment was 90.9% and 79.8%. There was a trend toward better survival in patients with Kt/V greater than 2.0, but it was not statistically significant. Peritoneal Kt/V did not impact survival in anuric patients. Malnourished patients had poorer survival than patients who were better nourished (p = 0.0259). After adjusting for age and diabetes, CNI was predictive of mortality but Kt/V and creatinine clearance were not.

CONCLUSIONS

This study demonstrates the importance of nutritional status over adequacy indices in predicting patient survival. There was a lack of correlation between nutritional status and conventional indices of dialysis adequacy.

Polymicrobial outbreak of intermittent peritoneal dialysis peritonitis during external wall renovation at a dialysis center

OBJECTIVE

To investigate an outbreak of peritonitis in intermittent peritoneal dialysis (IPD) patients.

DESIGN

An outbreak investigation was performed to identify the etiology of the polymicrobial outbreak, and a retrospective case-control study was conducted to assess the risk factors for development of peritonitis.

SETTING

Renal dialysis center.

PATIENTS

Ten episodes of peritonitis occurred in 8 of 61 patients over a 6-month period in which 669 IPD procedures were analyzed.

INTERVENTIONS

Field visit to renal dialysis center to examine the entire IPD procedure, inspect the hospital environment, and perform air bacterial count.

MAIN OUTCOME MEASURES

The environmental factors and risk factors contributing to the polymicrobial peritonitis outbreak in IPD patients. The incidence of IPD peritonitis was determined before and after interventions.

RESULTS

The causative organisms included Acinetobacter baumanii (6), Stenotrophomonas maltophilia (2), Pseudomonas aeruginosa (1), Candida albicans (1), C. tropicalis (1), Enterococcus (3), and Enterobacteriaceae (2). Four episodes of peritonitis involved infection by more than one organism. Air sampling of the environment detected a median of 110 colony forming units of bacteria per cubic meter of air, 10% of which were found to be Acinetobacter baumanii. The source of this polymicrobial outbreak was attributed to the bamboo scaffolding structure covering the external wall of the hospital during renovation. A retrospective case-control study indicated that the absence of the flush-before-fill step was a risk factor for development of peritonitis.

CONCLUSION

In addition to invasive aspergillosis in transplant or oncology patients, Acinetobacter peritonitis in dialysis patients should be considered another microbial cause of outbreak associated with hospital renovation.

Single dose diclofenac suppository reduces post-Cesarean PCEA requirements

PURPOSE

To assess the analgesic efficacy of administering, immediately after surgery, a single dose of diclofenac (100 mg suppository) to women who had undergone lower segment Cesarean section (LSCS) under combined spinal-epidural anesthesia, and received post-operative patient-controlled epidural analgesia (PCEA) with ropivacaine 0.2% and fentanyl 2 microg x ml(-1).

METHODS

Forty-eight ASA physical status I or II term parturients scheduled for elective LSCS under regional anesthesia were enrolled into this randomised double-blind study. The patient-controlled epidural analgesia device was programmed to deliver a bolus of 4 ml of local anesthetic mixture with a lockout period of ten minutes and an hourly limit of 12 ml. There was no baseline infusion. The study commenced upon the patient's first demand for analgesia post-operatively and the patients were assessed at one, six, 12 and 24 hr post-operatively for pain scores on movement, dermatomal level of sensory blockade, degree of motor blockade and volume of local anesthetic used. At conclusion of the study, patients' satisfaction scores were recorded.

RESULTS

The two groups of patients were similar demographically. Patients who received a diclofenac suppository used 52.8 +/- 17.8 ml of local anesthetic mixture while those who did not, used 74 +/- 25 ml (P <0.005). Pain scores and satisfaction scores did not differ significantly between the groups.

CONCLUSION

A single administration of 100 mg diclofenac suppository is effective in reducing post-Cesarean epidural local anesthetic/opioid requirements by 33% for the first 24 hr post-operatively.

Simultaneous removal and reinsertion of Tenckhoff catheters for the treatment of refractory exit-site infection

Exit-site infection (ESI) refractory to medical therapy is an important complication of continuous ambulatory peritoneal dialysis (CAPD). Between July 1994 and June 1998, 28 patients in our hospital underwent simultaneous removal and reinsertion of Tenckhoff catheters for the treatment of refractory ESI. The ESI was caused by Pseudomonas aeruginosa in 22 patients (78%), methicillin-resistant Staphylococcus aureus in 5 patients (18%), and diphtheroid bacilli in 1 patient (4%). The patients had received antibiotic treatment for a mean duration of 11.6 +/- 5.8 weeks (range: 3-28 weeks) before their operations. During each operation, the old Tenckhoff catheter was removed and a new catheter was inserted in the opposite side of the abdomen. CAPD was resumed after two weeks of intermittent peritoneal dialysis. All patients received intravenous antibiotic cover for seven days after the operation. Early post-operative complications were uncommon. At one year after the operation, 22 patients (78%) were free of ESI. Six patients (22%) had a recurrence of ESI 21.3 +/- 6 weeks (range: 16-32 weeks) after their operation. All new infections were treated successfully with antibiotics. Seven patients (25%) had one episode of peritonitis each, all of which resolved with intraperitoneal antibiotic treatment. We conclude that simultaneous removal and reinsertion of Tenckhoff catheters is a safe and effective method for the treatment of refractory ESI. The procedure alleviates the need for temporary hemodialysis and allows an early return to CAPD.

Lenses of SPARC-null mice exhibit an abnormal cell surface-basement membrane interface

SPARC (secreted protein acidic and rich in cysteine) is a matricellular protein involved in cell-matrix interactions. We have shown previously that mice deficient in SPARC develop posterior cortical cataract early in life that progresses to a mature opacity and capsule rupture. To evaluate the primary effects of SPARC deficiency in the lens, we examined the lenses of SPARC-null and wild-type mice by electron microscopy and immunohistochemistry to investigate whether ultrastructural abnormalities occur at the basement membrane (capsule)-lens cell interface in SPARC-null mice. The most notable feature in the lenses of SPARC-null mice, relative to wild-type animals, was the modification of the basal surface of the lens epithelial and fiber cells at the basement membrane (capsule) interface. Electron microscopy revealed numerous filopodial projections of the basal surface of the lens epithelial and fiber cells into the extracellular matrix of the anterior, posterior, and equatorial regions of the lens capsule. In 1 week old precataractous lenses, basal invasive filopodia projecting into the capsule were small and infrequent. Both the size and frequency of these filopodia increased in precataractous 3-4 week old lenses and were prominent in the cataractous 5-6 week old lenses. By rhodamine-phalloidin labeling, we confirmed the presence of basal invasive filopodia projecting into the lens capsule and demonstrated that the projections contained actin filaments. In contrast to the obvious abnormal projections at the interface between the basal surface of the lens epithelial and fiber cells and the lens capsule, the apical and lateral plasma membranes of lens epithelial cells and lens fibers in SPARC-null mice were as smooth as those of wild-type mice. We conclude that the absence of SPARC in the murine lens is associated with a filopodial protrusion of the basal surface of the lens epithelium and differentiating fiber cells into the lens capsule. The altered structures appear prior to the opacification of the lens in the SPARC-null model. These observations are consistent with one or more functions previously proposed for SPARC as a modulator of cell shape and cell-matrix interactions.