Prevalence of founder mutations in the BRCA1 and BRCA2 genes among unaffected women from the Bahamas.

Population-based testing for BRCA1/2 mutations detects a high proportion of carriers not identified by cancer family history-based testing. We sought to determine whether population-based testing is an effective approach to genetic testing in the Bahamas, where 23% of women with breast cancer carry one of seven founder mutations in the BRCA1 or BRCA2 gene. We determined the prevalence of founder BRCA mutations in 1847 Bahamian women without a personal history of breast or ovarian cancer, unselected for age or family history. We found that 2.8% (20/705) of unaffected women with a family history of breast/ovarian cancer and 0.09% (1/1089) of unaffected women without a family history carry a BRCA mutation. A total of 38% of unaffected women with a known mutation in the family were found to carry the familial mutation. We previously suggested that all Bahamian women with breast or ovarian cancer be offered genetic testing. These current data suggest that additionally all unaffected Bahamian women with a family history of breast/ovarian cancer should be offered genetic testing for the founder BRCA mutations.

Prevalence of PALB2 mutations in the Creighton University Breast Cancer Family Registry.

The purpose of this study is to determine the prevalence of PALB2 mutations among breast cancer families from the United States. The PALB2 gene was screened for mutations in 90 familial breast cancer patients from the Creighton University Breast Cancer Family Registry. These patients had previously tested negative for mutations in BRCA1 and BRCA2. Two of 90 breast cancer patients (2.2 %) were found to carry a truncating mutation in PALB2 (c.2411_2412delCT and c.2053delC). Both probands were diagnosed with breast cancer before age 35 and each had three relatives with breast cancer. Mutations in PALB2 are less common than BRCA1 and BRCA2 in familial breast cancer patients. However, testing for PALB2 mutations is a useful adjunct for patients undergoing testing for BRCA1 and BRCA2.

The prevalence of BRCA1 and BRCA2 mutations among young Mexican women with triple-negative breast cancer.

Various guidelines recommend that women with triple-negative breast cancer should be tested for BRCA1 mutations, but the prevalence of mutations may vary with ethnic group and with geographic region, and the optimal cutoff age for testing has not been established. We estimated the frequencies of BRCA1 and BRCA2 (BRCA) mutations among 190 women with triple-negative breast cancer, unselected for family history, diagnosed at age 50 or less at a single hospital in Mexico City. Patients were screened for 115 recurrent BRCA mutations, which have been reported previously in women of Hispanic origin, including a common large rearrangement Mexican founder mutation (BRCA1 ex9-12del). A BRCA mutation was detected in 44 of 190 patients with triple-negative breast cancer (23 %). Forty-three mutations were found in BRCA1 and one mutation was found in BRCA2. Seven different mutations accounted for 39 patients (89 % of the total mutations). The Mexican founder mutation (BRCA1 ex9-12del) was found 18 times and accounted for 41 % of all mutations detected. There is a high prevalence of BRCA1 mutations among young triple-negative breast cancer patients in Mexico. Women with triple-negative breast cancer in Mexico should be screened for mutations in BRCA1.

Strategies for recruitment of relatives of BRCA mutation carriers to a genetic testing program in the Bahamas.

The prevalence of BRCA1 and BRCA2 mutations among unselected breast cancer patients in the Bahamas is 23%. It is beneficial to advise relatives of mutation carriers that they are candidates for genetic testing. Women who test positive are then eligible for preventive interventions, such as oophorectomy. It is not clear how often relatives of women with a mutation in the Bahamas wish to undergo genetic testing for the family mutation. Furthermore, it is not clear how best to communicate this sensitive information to relatives in order to maximize patient compliance. We offered genetic testing to 202 first-degree relatives of 58 mutation carriers. Of 159 women who were contacted by the proband or other family member, only 14 made an appointment for genetic testing (9%). In contrast, among 32 relatives who were contacted directly by the genetic counselor, 27 came for an appointment (84%). This study suggests that for recruitment of relatives in the Bahamas, direct contact by counselor is preferable to using the proband as an intermediary.

Prevalence of BRCA1 and BRCA2 mutations in unselected breast cancer patients from Peru.

The prevalence of BRCA1 and BRCA2 mutations among breast cancer patients in Peru has not yet been explored. We enrolled 266 women with breast cancer from a National cancer hospital in Lima, Peru, unselected for age or family history. DNA was screened with a panel of 114 recurrent Hispanic BRCA mutations (HISPANEL). Among the 266 cases, 13 deleterious mutations were identified (11 in BRCA1 and 2 in BRCA2), representing 5% of the total. The average age of breast cancer in the mutation-positive cases was 44 years. BRCA1 185delAG represented 7 of 11 mutations in BRCA1. Other mutations detected in BRCA1 included: two 2080delA, one 943ins10, and one 3878delTA. The BRCA2 3036del4 mutation was seen in two patients. Given the relatively low cost of the HISPANEL test, one should consider offering this test to all Peruvian women with breast or ovarian cancer.

Long-term potential of in situ chemical reduction for treatment of polychlorinated biphenyls in soils.

Polychlorinated biphenyls (PCBs) are well-known for being hydrophobic and persistent in the environment. Although many treatment approaches have been demonstrated to result in degradation of PCBs in water or water/cosolvent systems, few examples exist where such approaches have been applied successfully for PCB degradation in soil-water systems. A possible explanation for the limited treatment of PCBs in soil-water systems is that reactants that are capable of degrading PCBs in the aqueous phase are unlikely to persist long enough to achieve meaningful treatment of slowly-desorbing PCBs associated with the soil phase. To investigate this explanation, laboratory studies were conducted to evaluate chemical reductants, including zero valent metals, palladium (Pd) catalyst, and emulsified zero valent iron (EZVI), for dechlorination of PCBs in the presence and absence of soil. In the absence of soil, Pd-catalyzed treatments (Pd with electrolytic ZVI or iron/aluminum alloy) achieved rapid destruction of a model PCB congener, 2-chlorobiphenyl, with half-lives ranging from 43 to 110 min. For treatment of soils containing Aroclor 1248 at an initial concentration of approximately 1,500 mg kg(-1), Pd-catalyzed treatments achieved no measurable enhancement over the background PCB depletion rate (i.e., that measured in the untreated control) of 5.3 mg kg(-1)week(-1). In the presence of soils, EZVI was the only approach evaluated that resulted in a clear enhancement in PCB dechlorination rates. EZVI achieved PCB concentration reductions of greater than 50% at an average rate of 19 mg kg(-1)week(-1). The results suggest that slow PCB desorption limits treatment effectiveness in soils.

Screening for BRCA1 and BRCA2 mutations among French-Canadian breast cancer cases attending an outpatient clinic in Montreal.

Study subjects were French-Canadian women with ductal carcinoma in situ (DCIS) or invasive breast cancer (incident or prevalent) who were treated and followed at a single breast cancer clinic affiliated with the Research Center of University of Montreal (CRCHUM), who were either aged less than 50 years at diagnosis or who were 50 years or older and with at least two affected first- or second-degree relatives. Subjects were tested for six founder mutations (three in BRCA1 and three in BRCA2); 1093 eligible cases were tested. Of these, 56 women (5.1%) were mutation carriers, including 43 BRCA2 carriers and 13 BRCA1 carriers. The prevalence of mutations was 5.3% for unselected women aged 50 and less and was 4.6% for familial cases over age 50. The prevalence of mutations was 3.3% for women with DCIS and was 5.3% for women with invasive cancer. It is rational to offer genetic testing to all French-Canadian women diagnosed recently or in the past with either DCIS or invasive breast cancer before age 50 or with familial breast cancer above age 50.

A comparison of the detection of BRCA mutation carriers through the provision of Jewish population-based genetic testing compared with clinic-based genetic testing.

BACKGROUND: Guidelines for genetic testing for BRCA1 or BRCA2 stipulate that a personal or family history of cancer is necessary to be eligible for testing. Approximately 2% of Ashkenazi Jewish women carry a mutation, but to date population-based testing has not been advocated. Little is known about the relative yield of a conventional genetic testing programme versus a programme of widespread testing in a population with common founder mutations. METHODS: We provided both referral-based and Jewish population-based testing between 2008 and 2012. We compared the numbers of BRCA mutation carriers identified through the two streams and estimated the number of genetic counselling hours devoted to each programme. RESULTS: From 2008 to 2012, 38 female carriers were identified through 487 referrals to our genetics centre (29 unaffected with cancer). During the same time, 6179 Jewish women were tested through our population-based programme and 93 mutation carriers were identified (92 unaffected with cancer). Fewer counsellor hours were devoted to the population-based than to the clinical referral-based testing programme. CONCLUSION: Genetic testing of all Jewish women above the age of 25 years will greatly expand the number of BRCA mutation carriers identified without a commensurate increase in the number of hours required for counselling.

BRCA1 and BRCA2 mutations among familial breast cancer patients from Costa Rica.

The contribution of mutations in BRCA1 and BRCA2 genes to the burden of breast cancer in Costa Rica has not been studied. We estimated the frequency of BRCA mutations among 111 Costa Rican women with breast cancer and a family history of breast cancer. These women were mainly from the metropolitan area of San José. A detailed family history was obtained from each patient and a blood sample was processed for DNA extraction. Mutations in BRCA1 and BRCA2 were sought using a combination of techniques and all mutations were confirmed by direct sequencing. Four different mutations were identified in five patients (four in BRCA2 and one in BRCA1) representing 4.5% of the total. Two unrelated patients were found to have a BRCA2 5531delTT mutation. Other BRCA2 mutations included C5507G and 6174delT. Only one BRCA1 mutation was found (C3522T). The family with the BRCA1 mutation had five cases of gastric cancer. Families with BRCA2 mutations were also reported to have cases of gastric and prostate cancers; however, the full range of cancers associated with BRCA1 and BRCA2 mutations in Costa Rica has not yet been established.

Radiation-enhancement of MDA-MB-231 breast cancer cell invasion prevented by a cyclooxygenase-2 inhibitor.

BACKGROUND: Recent evidences support that radiation can promote the invasion of cancer cells. As interactions between cancer cells and surrounding stromal cells can have an important role in tumour progression, we determined whether an irradiation to fibroblasts can enhance the invasiveness of breast cancer cells. The role of cyclooxygenase-2 (COX-2), an inflammatory enzyme frequently induced by radiotherapy, was investigated. METHODS: Irradiated 3T3 fibroblasts were plated in the lower compartment of invasion chambers and used as chemoattractant for non-irradiated human breast cancer cell MDA-MB-231, which are oestrogen receptor negative (ER(-)) and the oestrogen receptor positive (ER(+)) MCF-7 cells. Stimulation of COX-2 expression in irradiated 3T3 cells was measured by a semi-quantitative qPCR and western blot. Capacity of the major product of COX-2, the prostaglandin E2 (PGE(2)), to stimulate the production of the matrix metalloproteinase-2 (MMP-2) and cancer cell invasion were assessed with a zymography gel and invasion chambers. RESULTS: Irradiation (5 Gy) of 3T3 fibroblasts increased COX-2 expression and enhanced by 5.8-fold the invasiveness of non-irradiated MDA-MB-231 cells, while their migration was not modified. Addition of the COX-2 inhibitor NS-398 completely prevented radiation-enhancement of cancer cell invasion. Further supporting the potential role of COX-2, addition of PGE(2) has increased cancer cell invasion and release of MMP-2 from the MDA-MB-231 cells. This effect of radiation was dependant on the expression of membrane type 1 (MT1)-MMP, which is required to activate the MMP-2, but was not associated with the ER status. Although irradiated fibroblasts stimulated the invasiveness of MDA-MB-231 ER(-) cells, no enhancement was measured with the ER(+) cell line MCF-7. CONCLUSIONS: Radiation-enhancement of breast cancer cell invasion induced by irradiated 3T3 fibroblasts is not dependant on the ER status, but rather the expression of MT1-MMP. This adverse effect of radiation can be prevented by a specific COX-2 inhibitor.

Family history, BRCA mutations and breast cancer in Vietnamese women.

The purpose of this report is to estimate the proportions of familial and hereditary breast cancers among unselected cases of breast cancer in Vietnam. Two hundred and ninety-two unselected cases of incident breast cancer were recruited from the National Cancer Hospital, Hanoi, the largest cancer centre in Vietnam. Family histories were collected for 292 cases and a DNA sample was obtained for 259 cases. DNA samples were screened for mutations in the large exons of BRCA1 and BRCA2 using the protein truncation test and by allele-specific testing for 17 founder mutations which have been reported in other Asian populations. Complete gene sequencing was performed on two cases of familial breast cancer. Seven of 292 cases reported a relative with breast cancer and one patient reported a relative with ovarian cancer. A pathogenic BRCA mutation was detected in 2 of 259 cases; one BRCA1 carrier was diagnosed at age 51 and one BRCA2 carrier was diagnosed at age 42. Neither case reported a relative with breast or ovarian cancer. A family history of breast cancer is very uncommon among Vietnamese breast cancer patients. The frequency of pathogenic BRCA mutations in Vietnamese breast cancer patients is among the lowest reported worldwide.

The contribution of founder mutations to early-onset breast cancer in French-Canadian women.

In an ethnically-homogeneous population, it is valuable to identify founder mutations in cancer-predisposing genes. Founder mutations have been found in four breast-cancer-predisposing genes in French-Canadian breast cancer families. The frequencies of the mutant alleles have been measured neither in a large series of unselected breast cancer patients from Quebec, nor in healthy controls. These estimates are necessary to measure their contribution to the hereditary burden of breast cancer in Quebec and to help develop genetic screening policies which are appropriate for the province. We studied 564 French-Canadian women with early-onset invasive breast cancer who were treated at a single Montreal hospital. Patients had been diagnosed at age 50 or less, and were ascertained between 2004 and 2008. We screened all 564 patients for nine founder mutations: four in BRCA1, three in BRCA2 and one each in PALB2 and CHEK2. We also studied 6433 DNA samples from newborn infants from the Quebec City area to estimate the frequency of the nine variant alleles in the French-Canadian population. We identified a mutation in 36 of the 564 breast cancer cases (6.4%) and in 35 of 6443 controls (0.5%). In the breast cancer patients, the majority of mutations were in BRCA2 (54%). However, in the general population (newborn infants), the majority of mutations were in CHEK2 (54%). The odds ratio for breast cancer to age 50, given a BRCA1 mutation, was 10.1 (95% CI: 3.7-28) and given a BRCA2 mutation was 29.5 (95% CI: 12.9-67). The odds ratio for breast cancer to age 50, given a CHEK2 mutation, was 3.6 (95% CI: 1.4-9.1). One-half of the women with a mutation had a first- or second-degree relative diagnosed with breast or ovarian cancer. Thus, it can be concluded that a predisposing mutation in BRCA1, BRCA2, CHEK2 or PALB2 is present in approximately 6% of French-Canadian women with early-onset breast cancer. It is reasonable to offer screening for founder mutations to all French-Canadian women with breast cancer before age 50. The frequency of these mutations in the general population (0.5%) is too low to advocate population-based screening.

[Bortezomib-induced eruption: Sweet syndrome? Two case reports]. / Toxidermie au bortézomib : syndrome de Sweet? Deux cas.

BACKGROUND: Bortezomib (Velcade) is a proteasome inhibitor used in the treatment of myeloma and other blood dyscrasias. We report the cases of two patients who developed a peculiar toxic rash suggestive of Sweet's syndrome while receiving bortezomib; one patient also presented giant mucous membrane ulcerations. PATIENTS AND METHODS: Case 1: bortezomib treatment was started in a 62-year-old man for mantle cell lymphoma. Ten days after the first treatment cycle, giant, painful oral ulcerations were noted but they resolved spontaneously. One week after the second cycle, further oral ulceration appeared, this time with a papulonodular skin rash. Histology showed neutrophilic dermal infiltrates in the skin with predominantly lymphocytic inflammation of the oral mucosa. Bortezomib was stopped and all lesions resolved with colchicine treatment. Case 2: a 46-year-old woman was receiving bortezomib treatment for plasma cell leukemia. A febrile skin rash appeared two days after the first treatment cycle but resolved spontaneously. After the first bortezomib injection during the next cycle, painful papules and nodules appeared on the trunk. The skin biopsy results were consistent with Sweet's syndrome. The lesions disappeared spontaneously. Dexamethasone was administered concomitantly with bortezomib in the ensuing cycles and there was no relapse of the skin lesions. DISCUSSION: Bortezomib-induced skin lesions are common and usually do not justify treatment withdrawal. Published observations of bortezomib-induced eruption occasionally show clinical and histological features of Sweet's syndrome, but there has been no mention of oral mucosal ulcerations. In our cases, these could be related to bortezomib-induced neutrophilic dermatosis.

Breast cancer risks in women with a family history of breast or ovarian cancer who have tested negative for a BRCA1 or BRCA2 mutation.

Genetic testing for mutations in BRCA1 and BRCA2 is available in Canada for women with a significant family history of breast cancer. For the majority of tested women, a BRCA1 or BRCA2 mutation is not found, and counselling regarding breast cancer risk is based on the review of the pedigree. In this prospective study, we estimate breast cancer risks in women with a family history of breast cancer and for whom the proband tested negative for a mutation in BRCA1 or BRCA2. Families with two or more breast cancers under the age of 50 years, or with three cases of breast cancer at any age, and who tested negative for a BRCA1 or BRCA2 mutation were identified. Follow-up information on cancer status was collected on all first-degree relatives of breast cancer cases. The standardised incidence ratios (SIRs) for breast cancer were calculated by dividing the observed numbers of breast cancer by the expected numbers of breast cancers, based on the rates in the provincial cancer registries. A total of 1492 women from 365 families were included in the analyses. The 1492 first-degree relatives of breast cancer cases contributed 9109 person-years of follow-up. Sixty-five women developed breast cancer, compared to 15.2 expected number (SIR=4.3). The SIR was highest for women under the age of 40 (SIR=14.9) years and decreased with increasing age. However, the absolute risk was higher for women between the age of 50 and 70 (1% per year) years than for women between 30 and 50 (0.4% per year) years of age. There was no elevated risk for ovarian, colon or any other form of cancer. Women with a significant family history of breast cancer (ie, two or more breast cancers under the age of 50 years, or three or more breast cancers at any age), but who test negative for BRCA mutations have approximately a four-fold risk of breast cancer. Women in these families may be candidates for tamoxifen chemoprevention and/or intensified breast screening with an MRI.

Modeling the sorption kinetics of divalent metal ions to hematite.

The sorption kinetics of the divalent metals Zn, Co, Ni, and Cd to hematite were studied in single sorbate systems with high sorbate/sorbent ratios (from 1.67 to 3.33mol sorbate/mol sorption sites) in 10mM Na-piperazine N,N'-bis 2-ethane sulfonic acid (Na-PIPES) solution at pH 6.8. The experimental data showed a rapid initial sorption (half-time about 1min) followed by slower sorption that continued for 1-5 days. The sequence of fast to slow sorption kinetics was modeled by slow inner-sphere (IS) complexation in equilibrium with outer-sphere (OS) complexes. Although the OS reaction was fast and considered to be in equilibrium, the extent of OS complexation changed over time due to increased surface potential from the IS complexes. For example, the model showed that the dimensionless OS complexation function, K(os), decreased from 0.014 initially to 0.0016 at steady state due to sorption of 4x10(-5)M Zn(II) to 2gL(-1) hematite. Sorption rate constants, k(ads), for the various divalent metals ranged from 6.1 to 82.5M(-1)s(-1). Desorption rate constants, k(des), ranged from 5.2x10(-7) to 6.7x10(-5)s(-1). This study suggests that the conversion from OS to IS complex was the rate-determining step for the sorption of divalent metals on crystalline adsorbents.

Cloned genomic DNA of type 2 porcine circovirus is infectious when injected directly into the liver and lymph nodes of pigs: characterization of clinical disease, virus distribution, and pathologic lesions.

Infection of animals with a molecular viral clone is critical to study the genetic determinants of viral replication and virulence in the host. Type 2 porcine circovirus (PCV2) has been incriminated as the cause of postweaning multisystemic wasting syndrome (PMWS), an emerging disease in pigs. We report here for the first time the construction and use of an infectious molecular DNA clone of PCV2 to characterize the disease and pathologic lesions associated with PCV2 infection by direct in vivo transfection of pigs with the molecular clone. The PCV2 molecular clone was generated by ligating two copies of the complete PCV2 genome in tandem into the pBluescript SK (pSK) vector and was shown to be infectious in vitro when transfected into PK-15 cells. Forty specific-pathogen-free pigs at 4 weeks of age were randomly assigned to four groups of 10 each. Group 1 pigs served as uninoculated controls. Pigs in group 2 were each inoculated intranasally with about 1.9 x 10(5) 50% tissue culture infective doses of a homogeneous PCV2 live virus stock derived from the molecular clone. Pigs in group 3 were each injected intrahepatically with 200 microg of the cloned PCV2 plasmid DNA, and pigs in group 4 were each injected into the superficial iliac lymph nodes with 200 microg of the cloned PCV2 plasmid DNA. Animals injected with the cloned PCV2 plasmid DNA developed infection resembling that induced by intranasal inoculation with PCV2 live virus stock. Seroconversion to PCV2-specific antibody was detected in the majority of pigs from the three inoculated groups at 35 days postinoculation (DPI). Viremia, beginning at 14 DPI and lasting 2 to 4 weeks, was detected in the majority of the pigs from all three inoculated groups. There were no remarkable clinical signs of PMWS in control or any of the inoculated pigs. Gross lesions in pigs of the three inoculated groups were similar and were characterized by systemically enlarged, tan lymph nodes and lungs that failed to collapse. Histopathological lesions and PCV2-specific antigen were detected in numerous tissues and organs, including brain, lung, heart, kidney, tonsil, lymph nodes, spleen, ileum, and liver of infected pigs. This study more definitively characterizes the clinical course and pathologic lesions exclusively attributable to PCV2 infection. The data from this study indicate that the cloned PCV2 genomic DNA may replace infectious virus for future PCV2 pathogenesis and immunization studies. The data also suggest that PCV2, although essential for development of PMWS, may require other factors or agents to induce the full spectrum of clinical signs and lesions associated with advanced cases of PMWS.

The kinetic properties and sensitivities to inhibitors of lactate dehydrogenases (LDH1 and LDH2) from Toxoplasma gondii: comparisons with pLDH from Plasmodium falciparum.

Toxoplasma gondii differentially expresses two forms of lactate dehydrogenase in tachyzoites and bradyzoites, respectively, designated LDH1 and LDH2. Previously it was demonstrated that LDH1 and LDH2 share a unique structural feature with LDH from the malarial parasite Plasmodium falciparum (pLDH), namely, the addition of a five-amino acid insert into the substrate specificity loops. pLDH exhibits a number of kinetic properties that previously were thought to be unique to pLDH. In the present study, kinetic properties of LDH1 and LDH2 were compared with those of pLDH. LDH1 and LDH2 exhibit broader substrate specificity than pLDH. For both LDH1 and LDH2, 3-phenylpyruvate is an excellent substrate. For LDH2, 3-phenylpyruvate is a better substrate even than pyruvate. By comparison, pLDH does not utilize 3-phenylpyruvate. Both LDH1 and LDH2 can utilize the NAD analog 3-acetylpyridine adenine dinucleotide (APAD) efficiently, similar to pLDH. LDH1 and LDH2 are inhibited competitively by a range of compounds that also inhibit pLDH, including gossypol and derivatives, dihydroxynaphthoic acids, and N-substituted oxamic acids. The lack of substrate inhibition observed with pLDH is also observed with LDH2. By comparison, LDH1 differs from LDH2 in exhibiting substrate inhibition in spite of an identical residue (M163) at a cofactor binding site that is thought to be critical for production of substrate inhibition. For gossypol and gossylic iminolactone, but not the other gossypol derivatives tested, the in vitro inhibition of T. gondii LDH activity correlated with specific inhibition of T. gondii tachyzoite growth in fibroblast cultures.

Selective active site inhibitors of human lactate dehydrogenases A4, B4, and C4.

Human lactate dehydrogenases (LDH-A4, -B4, and -C4) are highly homologous with 84-89% sequence similarities and 69-75% amino acid identities. Active site residues are especially conserved. Gossypol, a natural product from cotton seed, is a non-selective competitive inhibitor of NADH binding to LDH, with K(i) values of 1.9, 1.4, and 4.2 microM for LDH-A4, -B4, and -C4, respectively. However, derivatives of gossypol and structural analogs of gossypol in the substituted 2,3-dihydroxy-1-naphthoic acid family exhibited markedly greater selectivity and, in many cases, greater potency. For gossypol derivatives, greater than 35-fold selectivity was observed. For dihydroxynaphthoic acids with substituents at the 4- and 7-positions, greater than 200-fold selectivity was observed. Inhibition was consistently competitive with the binding of NADH, with dissociation constants as low as 30 nM. By comparison, a series of N-substituted oxamic acids, which are competitive inhibitors of the binding of pyruvate to LDH, exhibited very modest selectivity. These results suggest that substituted dihydroxynaphthoic acids are good lead compounds for the development of selective LDH inhibitors. Selective inhibitors of LDH-C4 targeted to the dinucleotide fold may hold promise as male antifertility drugs. Selective inhibitors of LDH-A4 and -B4 may be useful for studies of lactic acidemia associated with ischemic events. More broadly, the results raise the question of the general utility of drug design targeted at the dinucleotide binding sites of dehydrogenases/reductases.

Metabolism of the 2-oxoaldehyde methylglyoxal by aldose reductase and by glyoxalase-I: roles for glutathione in both enzymes and implications for diabetic complications.

Numerous physiological aldehydes besides glucose are substrates of aldose reductase, the first enzyme of the polyol pathway which has been implicated in the etiology of diabetic complications. The 2-oxoaldehyde methylglyoxal is a preferred substrate of aldose reductase but is also the main physiological substrate of the glutathione-dependent glyoxalase system. Aldose reductase catalyzes the reduction of methylglyoxal efficiently (k(cat)=142 min(-1) and k(cat)/K(m)=1.8x10(7) M(-1) min(-1)). In the presence of physiological concentrations of glutathione, methylglyoxal is significantly converted into the hemithioacetal, which is the actual substrate of glyoxalase-I. However, in the presence of glutathione, the efficiency of reduction of methylglyoxal, catalyzed by aldose reductase, also increases. In addition, the site of reduction switches from the aldehyde to the ketone carbonyl. Thus, glutathione converts aldose reductase from an aldehyde reductase to a ketone reductase with methylglyoxal as substrate. The relative importance of aldose reductase and glyoxalase-I in the metabolic disposal of methylglyoxal is highly dependent upon the concentration of glutathione, owing to the non-catalytic pre-enzymatic reaction between methylglyoxal and glutathione.

Long-term survival and its relationship to membrane transport status in peritoneal dialysis.

We evaluated peritoneal membrane transport status (high, high-average, low-average, and low) of 35 patients on persistent peritoneal dialysis (PD) for 5-16 years. We noted that most of these patients (n = 21) had low-average transport by dialysate-to-plasma creatinine (D/PCr) ratio.