Presence of donor- and recipient-derived DNA in cell-free urine samples of renal transplantation recipients: urinary DNA chimerism

BACKGROUND

Previous studies have indicated that microchimerism is present in body tissues, peripheral blood, and plasma of recipients after organ transplantation. We hypothesize that donor-derived DNA may also be present in cell-free urine of renal transplant recipients and that the concentrations of urine DNA may be correlated with graft rejection.

METHODS

Thirty-one female patients who had renal transplantation were enrolled in the study. In women with male organ donors, the SRY gene on the Y chromosome was used as a marker for donor-derived DNA. Real-time quantitative PCR for the SRY and beta-globin genes was carried out on cell-free urinary DNA from these patients. Serial urine samples from a female renal transplant recipient undergoing an acute rejection episode were also collected and analyzed with the beta-globin quantitative PCR system.

RESULTS

SRY sequences were detected in the urine of 14 of 17 female patients with male organ donors. None of the 14 patients with female organ donors had detectable SRY sequences in urinary DNA. The median fractional concentration of donor-derived DNA was 8.7% (interquartile range, 1.9-26.4%). During the acute rejection episode, urinary concentrations of the beta-globin gene were markedly increased, with the concentrations returning rapidly to normal following antirejection treatment.

CONCLUSIONS

Our results demonstrate that urinary DNA chimerism is present following renal transplantation. The measurement of urinary DNA using quantitative PCR may be useful for the diagnosis and monitoring of graft rejection.

Acute renal failure in a patient with Rosai-Dorfman disease

Acute renal failure developed in a 57-year-old woman who had Rosai-Dorfman disease diagnosed 1 year previously on a cervical lymph node. Organ imaging showed diffuse masses infiltrating both kidneys. The renal biopsy showed a lymphoplasmacytic and histiocytic process extensively replacing the parenchyma, which is in keeping with Rosai-Dorfman disease of the kidneys. However, the typical lymphophagocytic cells were lacking. This case illustrates that diagnosis of Rosai-Dorfman disease in renal biopsy can be very difficult, requiring both exclusion of many benign and malignant lesions and a high index of suspicion for this condition. In particular, lymphoma was excluded based on the mixed polyclonal composition of inflammatory cells and the absence of atypical lymphoid proliferation. The renal function partially recovered after a course of therapy combining VP-16 (etoposide) and dexamethasone and remained stable over 4-year follow-up. This report emphasizes the importance of early diagnosis and intervention to safeguard renal function in extensive Rosai-Dorfman disease.

Clinical and biochemical characteristics of type 2 diabetic patients on continuous ambulatory peritoneal dialysis: relationships with insulin requirement

Although glycemic control has an important impact on the clinical outcomes of patients with diabetes undergoing dialysis, there is a paucity of data on the relationship between glucose metabolism and clinical parameters in these patients. In this study, we compared a cohort of 48 patients with type II diabetes undergoing continuous ambulatory peritoneal dialysis (CAPD) with 84 age- and sex-matched patients with type II diabetes with similar disease duration but normal renal function. Compared with those with normal renal function, patients with type 2 diabetes undergoing CAPD had greater serum angiotensin-converting enzyme activity (median, 57.4 U/L; range, 33.5 to 100.0 U/L v 46.9 U/L; range, 11.6 to 111.2 U/L; P < 0.005), fasting C-peptide (median, 9.1 ng/mL; range, 0.9 to 30.0 ng/mL v 2.2 ng/mL; range, 0.2 to 20.3 ng/mL; P < 0.0001) and triglyceride levels, and lower serum albumin concentrations. Among the patients undergoing CAPD, there was a preponderance of men in the insulin-treated group. Insulin-treated patients also had greater plasma albumin levels and body weights and lower fasting serum C-peptide levels (2.81 +/- 1.77 v 3.12 +/- 2.04 ng/mL; analysis of variance, P = 0.007 adjusted for fasting glucose concentration). Multivariate analysis showed duration of diabetes, hemoglobin A(1c) (HbA(1c)) level, and body weight were independent determinants of insulin requirement in patients undergoing CAPD. The daily insulin dosage required was related to the duration of diabetes (r = 0.5; P = 0.007). In summary, among patients with end-stage renal failure, insulin-treated patients had greater body weights and plasma albumin levels but lower cholesterol levels. Plasma C-peptide concentration and duration of diabetes were the main determinants of insulin requirement, reflecting a decrease in beta-cell reserve, whereas the daily insulin dose correlated mainly with body weight, HbA(1c) level, and duration of diabetes. Kt/V had no effect on insulin resistance or insulin requirement of the patients.

Measured-to-predicted creatinine generation ratio increases with time and decline in residual renal function in continuous ambulatory peritoneal dialysis

The expression of measured-to-predicted creatinine generation ratio (M/P) has been proposed as an index of compliance in continuous ambulatory peritoneal dialysis (CAPD) patients. Although M/P may not be sensitive enough for cross-sectional study, serial monitoring has been suggested to identify noncompliance. We attempted to evaluate serial changes of M/P from a nonselected group of CAPD patients. Sixty-three patients, all followed up for 2 years, were reviewed retrospectively. Their M/P ratios at years 0 and 2 were computed and compared. Baseline M/P had a normal distribution with a mean of 0.96 +/- 0.26. There was significant correlation between baseline M/P and residual glomerular filtration rate (GFR; r = -0.81; P < 0.0001). There were weak correlations between M/P and duration of dialysis (r = 0.52; P < 0.0001), body weight (r = -0.52; P < 0.0001), Kt/V (r = 0.31; P < 0.02), weekly creatinine clearance normalized to body surface area (r = 0.53; P < 0.0001), and serum albumin level (r = -0. 28; P < 0.05). After 2 years, M/P increased in 56 of 63 patients (88. 9%). Average M/P increased from 0.96 +/- 0.26 to 1.31 +/- 0.27 (P < 0.0001). Multivariant analysis showed M/P at year 0, which was largely determined by residual GFR, was the only independent factor affecting increase in M/P from year 0 to year 2. The general trend of increasing M/P was still present when only anuric patients were analyzed, although that was not statistically significant (1.21 +/- 0.14 to 1.32 +/- 0.24; P = 0.12). The finding of increasing M/P with time in CAPD patients, particularly those with significant residual renal function, suggests M/P may not be a reliable indicator of noncompliance, even for serial follow-up of the same patient. Better methods for assessment of compliance in CAPD patients are required.

Lack of association of angiotensin-converting enzyme (DD/II) and angiotensinogen M235T gene polymorphism with renal function among Chinese patients with type II diabetes

The prevalence of diabetic nephropathy is greater in nonwhite patients with type II diabetes, including the Chinese, and genetic variation appears to have a role. We examined angiotensin-converting enzyme (ACE) DD/II and angiotensinogen (Atg) M235T polymorphism in a cohort of Chinese patients with type II diabetes with an average duration of diabetes of 14 years. Group A (n = 88) did not have significant diabetic nephropathy (creatinine levels </= 130 micromol/L [</=1.48 mg/L], without macroalbuminuria), and group B (n = 80) had significant diabetic nephropathy (macroalbuminuria or creatinine level >130 micromol/L [>1.48 mg/d], and those undergoing dialysis). The two groups were matched in different aspects, including age, duration of diabetes, blood pressure, and glycemic control. The results showed: (1) no difference of genotype distribution between groups A and B (DD:DI:II, 14%:45%:41% v 8%:38%:54%; P = 0.20; TT:TM/MM, 70%:30% v 76%:24%; P = 0.43), (2) no evidence of synergistic effect of ACE (DD/II) and Atg M235T gene polymorphisms, (3) no difference of allele frequencies between groups A and B (D:I, 36%:64% v 27%:73%; P = 0.20 and T:M, 86%:16% v 86%:14%; P = 0.73), and (4) ACE activity was greatest in patients with DD genotype and least in those with II genotype (DD:DI:II = 66. 9 +/- 13.3 U/L:61.5 +/- 19.9 U/L:45.0 +/- 17.0 U/L; P < 0.005). The data do not support a role of ACE (DD/II) or Atg M235T polymorphism in the development of diabetic nephropathy in Chinese patients with type II diabetes, and no synergistic effect was found between them. Greater ACE activity was associated with DD genotype, and its role in diabetic nephropathy remains to be elucidated.

Comparison of double-bag and Y-set disconnect systems in continuous ambulatory peritoneal dialysis: a randomized prospective multicenter study

We performed a multicenter, single-blinded, prospective randomized study on the use of a double-bag disconnect system (B) versus a Y-set disconnect system (Y). The peritonitis rate, exit site infection, clinical outcome, and patients' acceptance to the procedure were assessed. A total of 120 new end-stage renal failure patients of three regional hospitals were randomized: 60 each to the B and the Y systems. The results of 60 patients on the B system and 51 on the Y system were analyzable. They were followed up for a median of 16 months. Peritonitis rates for the B and the Y systems were 33.5 and 29.4 patient-months per episode, respectively. Exit site infection rates for the B and Y systems were 17.4 and 16.0 patient-months per episode, respectively. Four catheters were removed in each group. Patients on the B system were hospitalized for 2.1 days per patient per year related to peritonitis and exit site infection, and those on the Y system were hospitalized for 1.2 days. There was no significant difference between the B and Y systems in the incidences of peritonitis (all causes and those due to coagulase-negative staphylococci), exit site infection, and in hospitalization days. However, there was a higher percentage of gram-positive infections in the Y system (52%) than in the B system (32%) and a lower percentage of gram-negative infections in the Y system (16%) than in the B system (32%). Patients on the B system had a better acceptance of the procedure than patients on the Y system, as assessed by a six-item, 10-point questionnaire (total score, 43.1 +/- 10.2 v 37.6 +/- 9.4; P < 0.005 at 1 month; 44.6 +/- 9.1 v 39.8 +/- 8.6; P < 0.01 at 6 months). From this study, it is concluded that the B and Y systems are similar in the incidences of peritonitis and exit site infection, although the B system is better accepted by patients. This is probably the first multicenter randomized study comparing the double-bag and Y-set disconnect system using only new patients who had never used other systems of continuous ambulatory peritoneal dialysis.

Synthesis and sulfatase inhibitory activities of (E)- and (Z)-4-hydroxytamoxifen sulfamates

We report the development of (E)- and (Z)-4-hydroxytamoxifen sulfamates as estrone sulfatase inhibitors, potential therapeutic agents for the treatment of breast cancer. Both compounds competitively inhibit estrone sulfatase isolated from rat liver with apparent Ki of 35.9 microM for (E)-4-hydroxytamoxifen sulfamate and an apparent Ki of > 500 microM for the (Z) isomer.

Development of (p-O-sulfamoyl)-N-alkanoyl-phenylalkyl amines as non-steroidal estrone sulfatase inhibitors

Estrogen levels in breast tumors of postmenopausal women are as much as 10 times higher than estrogen levels in plasma, presumably due to in situ formation of estrogen. The major source of estrogen in breast cancer cells may be conversion of estrone sulfate to estrone by the enzyme estrone sulfatase. Thus, inhibitors of estrone sulfatase are potential agents for treatment of estrogen-dependent breast cancer. Several steroidal compounds have been developed that are potent estrone sulfatase inhibitors, most notably estrone-3-O-sulfamate. However, these compounds and their metabolites may have undesired effects, including estrogenicity. To avoid the problems associated with a potentially active steroid nucleus, we designed and synthesized a series of nonsteroidal estrone sulfatase inhibitors, the (p-O-sulfamoyl)-N-alkanoyl phenylalkyl amines. The compounds synthesized vary in the length of their alkanoyl chain and in the number of carbons separating the phenyl ring and the carbonyl carbon. The ability of these compounds to inhibit estrone sulfatase activity was tested using human placental microsomes and intact cultured human breast cancer cells. Estrogenicity was also evaluated, using growth of estrogen-dependent human breast cancer cells. All of the test compounds inhibited estrone sulfatase activity of human placental microsomes to some extent, with the most effective compound having an IC50 value of 72 nM. In general, compounds with longer alkanoyl chains (12-14 carbons) were more effective than those with shorter chains. The test compounds also inhibited estrone sulfatase activity in intact cultures of MDA-MB-231 human breast cancer cells. Again, the longer chain compounds were more effective. In both the placental and breast cancer cell sulfatase assays, the optimal distance between the phenyl ring and the carbonyl carbon was 1-2 carbons. The MCF-7 cell proliferation assay revealed that estrone and estrone-3-O-sulfamate were both estrogenic, but the (p-O-sulfamoyl)-N-alkanoyl phenylalkyl amines were not. Our data indicate the utility of (p-O-sulfamoyl)-N-alkanoyl phenyl alkylamines for inhibition of estrone sulfatase activity. Furthermore, our data support the concept that nonsteroidal estrone sulfatase inhibitors may be useful as therapeutic agents for estrogen-dependent breast cancers.

Effective treatment of high-grade lymphoproliferative disorder after renal transplantation using autologous lymphocyte activated killer cell therapy

Posttransplantation lymphoproliferative disorders (PTLD) is not uncommon and can occur in 2% to 5% of solid organ recipients on immunosuppression. Epstein-Barr virus (EBV) infection or reactivation and intensive anti-T lymphocyte treatment are important pathogenetic factors for a large proportion of these disorders. Nonclonal lesions with polymorphous histology have a potential for regressing when the immunosuppressants are reduced or stopped. Clonal tumors with a monomorphous histology carry a poor prognosis, and the mortality rate for monoclonal lymphoma has been reported as high as 80%. We report a renal transplant recipient who developed high-grade monoclonal lymphoma only 4 months after a live-donor transplantation. The tumor was EBV positive. Reduction of immunosuppressants resulted in minimal regression of the tumor. The patient was treated with adoptive immunotherapy using ex vivo generation of autologous lymphocyte activated killer (LAK) cells. She had leukapheresis, and autologous peripheral blood mononuclear cells were obtained and cultured in interleukin-2 (IL-2)-rich medium for 9 to 10 days. The IL-2-activated LAK cells were reinfused into the patient without any systemic administration of IL-2. The patient experienced no side effects during the infusion. There was no rejection episode, and the renal function of the patient remained stable after treatment. Computed tomography scan performed 2 months after the infusion showed marked regression of the lesions in the liver and spleen. Five months later, magnetic resonance imaging showed complete resolution of the tumor lesions. Ultrasonography 13 months after the LAK cell infusion showed no lesion. The allograft function was not affected after treatment. Adoptive immunotherapy using IL-2-activated autologous LAK cells was effective in treating this renal transplant patient with EBV-positive high-grade lymphoma. The patient's kidney allograft functioned well without any rejection.

Factors associated with active systemic lupus erythematosus after endstage renal disease

OBJECTIVE

Activity of systemic lupus erythematosus (SLE) often declines after patients reach endstage renal disease (ESRD). However, extrarenal activity is not uncommon, especially during the first few years of dialysis. We reviewed the clinical course of SLE patients with ESRD treated in our unit over the past 10 years, and tried to identify factors associated with postdialysis activity.

METHOD

A retrospective study of 18 patients with SLE (6 males) who received maintenance dialysis in our center from 1987 to 1996. Their clinical details, organ system manifestations, serologic profile, and treatment were reviewed. Patients with and without lupus flares after maintenance dialysis were compared.

RESULTS

Duration of followup was 43.4 +/- 32.7 months before dialysis and 33.8 +/- 28.9 months afterwards (4 hemodialysis, 14 peritoneal dialysis). Nine patients experienced 32 lupus postdialysis flares. The frequency was 0.63 flare per patient-year. Twenty flares (62.5%) developed within the first year of dialysis. Compared with the other 9 patients who had no flares, patients with flares were younger (median age at diagnosis of SLE 24 vs 33 years; median age when dialysis was initiated 26 vs 37 years; p < 0.05 both, Mann-Whitney U test) and more likely to have history of seizure (6 in 9 vs 1 in 9 patients, p < 0.05, Fisher's exact test). There was a trend that patients with history of serositis and vasculitis were also associated with postdialysis activity, although this was not statistically significant.

CONCLUSION

Postdialysis flare of SLE is not uncommon, particularly during first year of dialysis. Younger patients and those with history of seizure may have higher risk of postdialysis lupus flare. Careful followup is warranted, especially in potential transplant recipients.

Coexistence of Kaposi's sarcoma and tuberculosis in a renal transplant recipient

BACKGROUND

We describe a case of Kaposi's sarcoma that developed in a renal transplant recipient as early as 5 months after the transplant.

METHOD

The Kaposi's sarcoma evolved in an aggressive manner, involving the oral mucosa, the cervical and mediastinal lymph nodes, the gastrointestinal tract, and possibly the lung. Histological features of tuberculosis were also detected incidentally on an excisional biopsy of the lymph node. The patient was given 12 months of antituberculous chemotherapy. At the same time, immunosuppression was gradually tapered over a 2- to 3-week period.

RESULTS

Despite the aggressive nature of the disease, the Kaposi's sarcoma regressed completely without the institution of chemotherapy. The patient remained disease-free after a follow-up period of 30 months. The kidney allograft, however, was rejected and the patient required dialysis again.

CONCLUSION

Although lymphadenopathy is a well-recognized feature in organ transplant recipients who develop Kaposi's sarcoma, one has to watch out for other coexisting diseases, such as tuberculosis, lymphoma, and cytomegalovirus infection.

Development of potent non-estrogenic estrone sulfatase inhibitors

Estrogen levels in breast tumors of post-menopausal women are as much as 10 times higher than estrogen levels in plasma, presumably due to in situ formation of estrogen. The major source of estrogen in breast cancer cells may be conversion of estrone sulfate to estrone by the enzyme estrone sulfatase. Thus, inhibitors of estrone sulfatase have potential for the treatment of estrogen-dependent breast cancers. Several steroidal agents have been developed that are potent estrone sulfatase inhibitors, most notably estrone-3-O-sulfamate. These compounds may have undesired actions, especially estrogenicity. Recently, non-steroidal estrone sulfatase inhibitors have been designed that avoid the problems associated with an active steroid nucleus; however, these have not achieved the potency of estrone-3-O sulfamate. We have designed and synthesized a series of compounds, 17 beta-(N-alkylcarbamoyl)-estra-1,3,5(10)-trien-3-O-sulfamates (6a-d) and 17 beta-(N-alkanoyl)-estra-1,3,5(10)-trien-3-O-sulfamates (11a-d) that combine the structural features of the steroidal estrone sulfatase inhibitors with a membrane insertion region that should increase the affinity for the sulfatase enzyme and decrease the estrogenicity of the steroid. We tested the compounds for estrone sulfatase inhibition by measuring estrone sulfatase activity in intact cultures of human breast cancer cells (MDA-MB-231). We tested for estrogenicity by measuring growth of estrogen-dependent MCF-7 human breast cancer cells. All of the test compounds (10 nM) substantially inhibited estrogen sulfatase activity of intact MDA-MB-231 cells. Dose-response analysis indicated an IC50 of approximately 0.5 nM for two of the compounds (6a and 11a). In the test for estrogenicity, estrone and estrone-3-O-sulfamate significantly stimulated MCF-7 cell growth. In contrast, neither the 17 beta-(N-alkylcarbamoyl)-estra-1,3,5,(10)-trien-3-O-sulfamates++ + nor the 17 beta-(N)-alkanoyl)-estra-1,3,5,(10)-trien-3-O-sulfamates stimulated growth of MCF-7 cells at a concentration of 1 microM, indicating that they are not estrogenic at levels 2000 times greater than their IC50 for estrone sulfatase. Our data indicate the utility of the new compounds for inhibition of breast cancer cell estrone sulfatase activity. Further, our data support the concept that estrone sulfatase inhibitors may be useful as therapeutic agents for estrogen-dependent breast cancers.

Association of HLA class-II genes and anti-neutrophil cytoplasmic antibodies in Chinese patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease is common in the West but rare in China. The genetic factor predisposing to the disease is unclear. Ulcerative colitis (UC) is found to be associated with HLA DR2 alleles in the West. Subgroups of UC patients have been further defined by the presence of anti-neutrophil cytoplasmic antibodies (ANCA).

METHODS

We attempted to define the HLA class-II genes (DRbeta, DQalpha, DQbeta) and their relationship with ANCA in southern Chinese patients with UC. Patients were tested for class-II genes by restriction fragment length polymorphism and polymerase chain reactions. The indirect immunofluorescence test was used to detect ANCA in the sera. Ethnically matched normal controls were used for comparison.

RESULTS

In ANCA-positive UC patients (n = 18) there was a strong association with HLA-DQalpha1c allele (P < 0.0001) when compared with controls (n = 104). This association was not found in ANCA-negative UC patients (n = 10) (P = 0.21).

CONCLUSIONS

In Chinese UC patients positive ANCA is associated with the HLA-DQalpha1c allele, which is not the case in Caucasian patients.

Pain perception following subcutaneous injections of citrate-buffered and phosphate-buffered epoetin alpha

Subcutaneous injection of citrate-buffered epoetin alpha (EPO-alpha) causes pain. Substitution of citrate buffer with a phosphate buffer in the EPO-alpha resulted in a significant reduction in duration and severity of pain. It is possible that sodium citrate which is present in the EPO-alpha may be the agent that causes discomfort in the patients.

Chronic steroid sulfatase inhibition by (p-O-sulfamoyl)-N-tetradecanoyl tyramine increases dehydroepiandrosterone sulfate in whole brain

Dehydroepiandrosterone sulfate (DHEAS) is a neurosteroid which functions as a negative allosteric modulator of the GABA(A) receptor-gated chloride channel. Steroid sulfatase inhibitors including (p-O-sulfamoyl)-N-tetradecanoyl tyramine (DU-14), can potentiate the blockade of the amnestic effects of scopolamine by exogenously administered DHEAS. Moreover, when administered over a 15 day period, DU-14 can block scopolamine amnesia without the concurrent administration of DHEAS. Since the enzyme, steroid sulfatase, facilitates the hydrolysis of the sulfate moiety from DHEAS, the intent of this study was to determine whether chronic administration of DU-14 could increase whole brain concentrations of endogenous DHEAS. Rats were administered DU-14 or corn oil vehicle for 15 days. Following the last day the animals were sacrificed and the brains were removed and analyzed for DHEAS content. DU-14 increased the whole brain concentration of DHEAS 77.6%, from 0.65 +/- 0.06 to 1.15 +/- 0.12 microg/g (mean +/- SEM). This result suggests that steroid sulfatase inhibitors may enhance cognitive function following chronic treatment by increasing the concentration of excitatory neurosteroids such as DHEAS in the brain. Steroid sulfatase inhibitors, therefore, may provide a novel mechanism for facilitating central nervous system function.

Enhanced plasma DHEAS, brain acetylcholine and memory mediated by steroid sulfatase inhibition

Steroid sulfatase inhibitors can alter the metabolism of neurosteroids which modulate brain function. Administration of the non-steroidal steroid sulfatase inhibitor (p-O-sulfamoyl)-N-tetradecanoyl tyramine (DU-14) to rats for 15 days increased plasma dehydroepiandrosterone sulfate (DHEAS) concentrations by 88.2%, decreased plasma dehydroepiandrosterone (DHEA) concentrations by 84.6%, increased hippocampal acetylcholine (ACh) release determined via in vivo microdialysis by almost 3-fold, and produced a significant blockade of scopolamine-induced amnesia as measured by a passive avoidance test. These results suggest DHEAS rather than DHEA enhances brain cholinergic function and that steroid sulfatase inhibition may become an important tool for enhancing neuronal functions, such as memory, mediated by excitatory neurosteroids.

Association of IgA nephropathy with T-cell receptor constant alpha chain gene polymorphism

T-cell receptor (TCR) proteins recognize a complex of an antigen-derived peptide bound to the cell surface products of the major histocompatibility complex (MHC) that could be of importance in the immunopathogenesis of IgA nephropathy (IgAN). Previous studies found no difference on TCR constant beta chain gene frequencies in IgAN compared with control. Yet no study on the TCR alpha gene in IgAN was reported. We studied the TCR C alpha gene polymorphisms by restriction fragment length polymorphism (RFLP) in 53 patients with IgAN and in comparison with 67 healthy controls. The patients were also classified into different histopathological grading (I, II, and III with increasing histological severity) and renal functions. The extracted DNA were digested with Taq I enzymes and probed with a full-length TCR-alpha cDNA clone p1.2alpha probe. A 7-kb C-alpha Taq 1 fragment is found in 32 of 53 patients (60.3%) compared with 26 of 67 controls (38.8%) (P < 0.05). There was no association of any polymorphic fragment, including the 7-kb fragment, with either the histological grading or renal function. It is concluded that the TCR C-alpha gene is associated with IgAN but not with the prognosis of the disease.

In vitro effects of simulated gastric juice on swallowed metal objects: implications for practical management

BACKGROUND

Swallowed metal objects often pose a technical challenge for the endoscopist. We studied in vitro the effects of simulated gastric juice on metal objects commonly encountered in endoscopic practice and measured the physical-chemical changes.

METHOD

Razor blades, disc batteries, and pennies were incubated in simulated gastric juice at 37 degrees C. The weights of the objects were recorded hourly. When no change could be detected, the solution was subjected to mass spectrometry to verify absence of effect. The findings were correlated with clinical observation in one patient who swallowed razor blades repeatedly.

RESULTS

Dissolution of the razor blade was proportional to the duration of acid immersion. At 24 hours, the blades weighed 63% of the original weight. Double-edged razor blades could be broken with a snare at 15 hours. The thickened back of the single-edged blade totally dissolved in 2 hours. No leak of contents could be detected with disk batteries. Pennies were unaffected.

CONCLUSION

Corrosion of razor blades occurs rapidly in the normal stomach. Within 24 hours double-edged blades become fragile and can be broken with a snare. This observation may guide the timing of endoscopic removal. Modern disk batteries are acid resistant for 24 hours.

Dialysis adequacy of Asian patients receiving small volume continuous ambulatory peritoneal dialysis

The usage of three x 2 liter daily exchanges is adopted as the standard CAPD regime in Hong Kong over the last 10 years due to budgetary constraint. This dialysis prescription is considered suboptimal in Western standard. However, the necessity of maintaining Kt/V > 1.7 for CAPD dialysis adequacy is not unanimously agreed. We performed a cross-sectional study of 117 patients on CAPD. Seventy-eight percent of our patients had 3 x 2 liter daily exchange while the rest had 4 daily exchanges. Fifteen percent of patients were diabetic. Patients with Kt/V < 1.7 were similar to those with Kt/V > 1.7 in age, duration of CAPD, BUN, plasma creatinine, albumin, peritonitis rate, and incidence of hypertension. Patients with Kt/V > or = 1.7 had higher hemoglobin, higher nPCR, more residual renal function; and more of them received 4 daily exchanges. Their peritoneal permeability did not differ. Their employment and rehabilitation status was also similar. Our 5-year survival was 79% despite a lower Kt/V. Notably, the protein catabolic rate of our patients was higher than that in Western patients. This is likely due to dietary difference. Our study suggests small-volume dialysis may be acceptable in Asian population with smaller body size given the financial constraint.

Synthesis of sodium androst-5-ene-17-one-3 beta-methylene sulfonate

The synthesis of sodium androst-5-ene-17-one-3 beta-methylene sulfonate 2, a stable analog of memory-enhancing neurosteroid dehydroepiandrosterone sulfate, is described. The synthesis of compound 2 is carried out in six steps from dehydroepiandrosterone.

Structure-activity relationship studies of the amide functionality in (p-O-sulfamoyl)-N-alkanoyl tyramines as estrone sulfatase inhibitors

Recently, we reported the synthesis and biomedical studies of a series of (p-O-sulfamoyl)-N-alkanoyl tyramines as nonsteroidal estrone sulfatase inhibitors. One of the most potent inhibitors in this series is (p-O-sulfamoyl)-N-tridecanoyl tyramine 1 with an 1C50 value of 61.3 nM. In this study, we synthesized four analogs of 1 (compounds 2-5) to investigate the structure-activity relationships of the amide functionality in (p-O-sulfamoyl)-N-tridecanoyl tyramine. Replacement of the amide functionality in 1 with an ethylene moiety to form the alkyl analog 5 resulted in complete loss of sulfatase inhibitory activity (IC50 of 61.3 nM vs. > 20 microM). The keto, hydroxy, and ester analogs (inhibitors 2-4) are 8-15 times less in affinity to the sulfatase than inhibitor 1. However, their inhibitory activities are significantly higher than the alkyl analog 5. The results suggest that the amide functionality is favorable for sulfatase inhibitory activity and that there may be a hydrogen bonding component to the enzyme interaction in this region.