A de novo mutation in KIT causes white spotting in a subpopulation of German Shepherd dogs

Although variation in the KIT gene is a common cause of white spotting among domesticated animals, KIT has not been implicated in the diverse white spotting observed in the dog. Here, we show that a loss-of-function mutation in KIT recapitulates the coat color phenotypes observed in other species. A spontaneous white spotting observed in a pedigree of German Shepherd dogs was mapped by linkage analysis to a single locus on CFA13 containing KIT (pairwise LOD = 15). DNA sequence analysis identified a novel 1-bp insertion in the second exon that co-segregated with the phenotype. The expected frameshift and resulting premature stop codons predicted a severely truncated c-Kit receptor with presumably abolished activity. No dogs homozygous for the mutation were recovered from multiple intercrosses (P = 0.01), suggesting the mutation is recessively embryonic lethal. These observations are consistent with the effects of null alleles of KIT in other species.

Necrotizing meningoencephalitis of Pug dogs associates with dog leukocyte antigen class II and resembles acute variant forms of multiple sclerosis

Necrotizing meningoencephalitis (NME) is a disorder of Pug Dogs that appears to have an immune etiology and high heritability based on population studies. The present study was undertaken to identify a genetic basis for the disease. A genome-wide association scan with single tandem repeat (STR) markers showed a single strong association near the dog leukocyte antigen (DLA) complex on CFA12. Fine resolution mapping with 27 STR markers on CFA12 further narrowed association to the region containing DLA-DRB1, -DQA1 and, -DQB1 genes. Sequencing confirmed that affected dogs were more likely to be homozygous for specific alleles at each locus and that these alleles were linked, forming a single high risk haplotype. The strong DLA class II association of NME in Pug Dogs resembles that of human multiple sclerosis (MS). Like MS, NME appears to have an autoimmune basis, involves genetic and nongenetic factors, has a relatively low incidence, is more frequent in females than males, and is associated with a vascularly orientated nonsuppurative inflammation. However, NME of Pug Dogs is more aggressive in disease course than classical human MS, appears to be relatively earlier in onset, and involves necrosis rather than demyelination as the central pathobiologic feature. Thus, Pug Dog encephalitis (PDE) shares clinical features with the less common acute variant forms of MS. Accordingly, NME of Pug Dogs may represent a naturally occurring canine model of certain idiopathic inflammatory disorders of the human central nervous system.

DOGSET: pre-designed primer sets for fine-scale mapping and DNA sequence interrogation in the dog

DOGSET is an online resource that provides access to primer sequences that have been computationally mined from the reference genome using heuristic algorithms. The electronic repository includes PCR primers corresponding to 32,135 markers for genetic mapping and 334,657 sequence-tagged gene elements for targeted re-sequencing and mutation discovery. A customized report that tailors primer design to wet bench protocols can be exported for a region of interest by specifying genome coordinates in a graphical user interface.

Evidence for unique association signals in SLE at the CD28-CTLA4-ICOS locus in a family-based study

CD28, CTLA4 (cytotoxic T lymphocyte-associated protein 4) and ICOS (inducible T cell co-stimulator) are good candidate genes for systemic lupus erythematosus (SLE) because of their role in regulating T cell activation. CTLA4 inhibits CD28-mediated T cell activation. CTLA4 is expressed on CD4+ and CD8+ activated T cells, and also B cells, but CD28 and ICOS are largely restricted to T cells. An interval encompassing the CD28-CTLA4-ICOS locus on chromosome 2q33 was linked to lupus in two genome-wide linkage scans. This large family-based association study in 532 UK SLE families represents the first high-density genetic screen of 80 SNPs at this locus. There are seven haplotype blocks across the locus. In CTLA4, the strongest signal comes from two variants, located 2.1 kb downstream from the 3'-UTR. These polymorphisms, rs231726 (SNP 43) and rs231726 (SNP 44), are in complete linkage disequilibrium (LD) (r(2)=1) and are associated with SLE P=0.0008 (GH) and P=0.01 (family-based association test). There is also a signal in the distal 3' flanking region of CTLA4/ICOS promoter (P=0.003). There was no confirmation of published associations for SLE in the promoter or coding region of CTLA4. These SLE risk alleles are more distal than those identified in Graves' disease and are in LD with Graves' disease protective alleles identified in both of these regions of CTLA4 (Ueda et al. 2003). These factors suggest an SLE-specific pattern of association. The functional consequences of the associated polymorphisms are likely to influence CTLA4 expression, although it is possible that genetically modulated ICOS expression is involved in SLE susceptibility.

Circulating antibodies to guanosine in systemic lupus erythematosus: correlation with nephritis and polyserositis by acute and longitudinal analyses

Systemic lupus erythematosus (SLE) is characterized by autoantibodies, including antibodies to the nucleosides of DNA. Guanosine is the most immunogenic nucleoside. In this study serum antiguanosine antibody levels were compared with disease activity, determined by their SLEDI score, in 86 patients with SLE. Sera from these patients were tested, by ELISA, for autoantibodies to guanosine, single-stranded DNA (ssDNA), and double-stranded DNA (dsDNA). Anti-double-stranded DNA levels were also measured by RIA. Resultant values from these assays were correlated with SLE disease activity, and compared with specific features of SLE. The strongest correlation was higher levels of antiguanosine antibodies in patients with active lupus nephritis and polyserositis compared to patients with inactive disease (P < 0.0001). Antiguanosine levels also correlated with arthritis (P < 0.006), CNS lupus (P < 0.005), and hematologic manifestations of SLE (P < 0.002). To test the validity of this association in chronic SLE, serum antiguanosine antibodies were measured in patients with SLE at various phases of disease activity. Twelve patients with SLE had serum samples drawn at active, active-improved, and inactive phases over a 3-7 y period. Differences were significant for serum antiguanosine antibodies in the active group compared to the inactive group (P < 0.05) and the active vs the active-improved group (P < 0.02), unlike those for dsDNA and ssDNA by ELISA or RIA. Antiguanosine antibodies correlated more closely with disease activity in SLE patients in this longitudinal study than either anti-dsDNA or ssDNA antibodies. Thus, antibodies to guanosine correlated as well or better with disease activity than the other anti-DNA antibodies measured and should be considered to contribute to the pathology of SLE, especially lupus nephritis.

Prevention of recurrent central venous stenosis using endovascular irradiation following stent placement in hemodialysis patients

This study was done to evaluate the outcome after brachytherapy (BT) given to prevent restenosis after stent insertion for central venous stenosis in patients with ipsilateral hemodialysis arteriovenous fistulas (AVF). Angioplasty and stenting were performed on 9 primary central venous stenoses in 8 patients with AVF followed by BT, delivering Iridium-192 radiation using an afterloading technique. BT was also administered to three patients with five recurrent stenoses at the stent margins. There was no residual stenosis after angioplasty and stenting. Venographic follow-up (77-644 days, mean 272 days) showed no restenosis in seven primary stenoses. New strictures (45%-100%) developed at the stent margin in six veins (five patients). Angioplasty or stenting was performed for five margin stenoses in three patients, followed by a second BT. Residual stenosis before BT was 0-30%. In our venographic follow-up (140-329 days, mean 215 days), three restenoses occurred (35%-100%). All progressed to complete occlusion on later venographic follow-up irrespective of whether BT was given to the stent margin or not. The mean primary and assisted primary patency of the central veins were 359 days and 639 days, respectively. Endovascular irradiation with a noncentering source does not prolong the patency after angioplasty and stenting of central venous stenosis in hemodialysis patients.

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.

Excessive tumor-elaborated VEGF and its neutralization define a lethal paraneoplastic syndrome

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen and key regulator of both physiologic and pathologic (e.g., tumor) angiogenesis. In the course of studies designed to assess the ability of constitutive VEGF to block tumor regression in an inducible RAS melanoma model, mice implanted with VEGF-expressing tumors sustained high morbidity and mortality that were out of proportion to the tumor burden. Documented elevated serum levels of VEGF were associated with a lethal hepatic syndrome characterized by massive sinusoidal dilation and endothelial cell proliferation and apoptosis. Systemic levels of VEGF correlated with the severity of liver pathology and overall clinical compromise. A striking reversal of VEGF-induced liver pathology and prolonged survival were achieved by surgical excision of VEGF-secreting tumor or by systemic administration of a potent VEGF antagonist (VEGF-TRAP(R1R2)), thus defining a paraneoplastic syndrome caused by excessive VEGF activity. Moreover, this VEGF-induced syndrome resembles peliosis hepatis, a rare human condition that is encountered in the setting of advanced malignancies, high-dose androgen therapy, and Bartonella henselae infection. Thus, our findings in the mouse have suggested an etiologic role for VEGF in this disease and may lead to diagnostic and therapeutic options for this debilitating condition in humans.

Mutation analyses of 268 candidate genes in human tumor cell lines

We have performed a homozygous deletion screen on 268 candidate genes in 90 human tumor cell lines derived from multiple types of cancers. Most of the candidate genes investigated have been proposed to be involved in cellular processes that are germane to cancer progression, such as cell cycle control, genome maintenance, chromatin remodeling, cell adhesion, and apoptosis. We have detected novel homozygous deletions affecting four independent loci: Brahma-related gene (SMARCA4) on chromosome 19p in the TSU-Pr1 prostate and A427 lung carcinoma lines, Map Kinase Kinase 3 (MAP2K3) on 17q in the NCI-H774 lung tumor cell line, TMPRSS2 on 21q in the Bx PC-3 pancreatic carcinoma line, and Cadherin 6 (CDH6) on 5p in the SK-LU-1 lung carcinoma line. Subsequent analyses of the coding sequences of these four genes using cDNAs from a panel of tumor cell lines revealed multiple sequence variants. The results of this mutation study serve to demonstrate the feasibility of performing high-throughput screens of candidate genes in tumor cell lines to identify genes that may be targeted for mutation during the development of cancer.

Prospective study on renal outcome of IgA nephropathy superimposed on diabetic glomerulosclerosis in type 2 diabetic patients

BACKGROUND AND METHODS

In order to examine the clinical outcome of IgA nephropathy (IgAN) superimposed on diabetic glomerulosclerosis in type 2 patients we studied 36 Chinese patients (26 men, 10 women), who were recruited for renal biopsy when they had proteinuria of more than 1 g/day. Twenty-seven had isolated diabetic glomerulosclerosis and nine had IgAN superimposed on diabetic glomerulosclerosis (combined). Renal function was assessed by serial serum creatinine, 24-h urine protein and creatinine measurements. Patient survival rate, incidence of end-stage renal disease (ESRD), blood pressure, and glycaemic control status were determined.

RESULTS

The age at the time of renal biopsy was younger for the combined group when compared with the diabetic glomerulosclerosis group (44+/-3.6 vs 58+/-2.1 years, P=0.006). The duration of diabetes was, however, similar for the two groups (8.0+/-2.3 vs 6.7+/-1.2 years, P=NS). After a mean follow-up of 31.6+/-15.3 months, 15 patients (one in the combined group and 14 in the diabetic glomerulosclerosis group) developed ESRD. Nine patients (all in the diabetic glomerulosclerosis group) died during follow-up. With similar glycaemic and blood pressure control, the two groups had comparable rate of decline of creatinine clearance (CrCl) (-0.73+/-0.26 vs -0.73+/- 0.18 ml/min/1.73 m(2)/month, P=NS), final serum creatinine (363+/-134 vs 426+/-52 micromol/l, P=NS) and proteinuria levels (4.3+/-0.9 vs 4.4+/-0.6 g/day, P=NS), as well as CrCl (44.1+/-19.0 vs 33.4+/-6.9 ml/min/ 1.73 m(2), P=NS).

CONCLUSION

It is concluded that the superimposed IgAN does not significantly alter the medium-term clinical outcome of patients with diabetic glomerulosclerosis.

Species dependence for binding of small molecule agonist and antagonists to the C5a receptor on polymorphonuclear leukocytes

This study investigated the receptor binding affinities of a C5a agonist and cyclic antagonists for polymorphonuclear leukocytes (PMNs) isolated from human, sheep, pig, dog, rabbit, guinea pig, rat and mouse. The affinities of the two small molecule antagonists, F-[OPdChaWR] and AcF-[OPdChaWR], and the agonist, YSFKPMPLaR, revealed large differences in C5a receptor (C5aR) affinities between species. The antagonists bound to human, rat and dog PMNs with similar high affinities, but with lower affinities to PMNs from all other species. The C5a agonist also bound with varying affinities between species, but showed a different affinity profile to the antagonists. In contrast, recombinant human C5a had similar affinity for PMNs of all species investigated. The low correlation between the affinities of the antagonists and the agonist between species either suggests that different receptor residues are important for distinguishing between agonist/antagonist binding, or that the agonist and antagonist peptides bind to two distinct sites within the C5aR.

An inducible melanoma model implicates a role for RAS in tumor maintenance and angiogenesis

The established tumor is maintained through complex and poorly understood host-tumor interactions guiding processes such as angiogenesis. The numerous and diverse genetic alterations that accompany tumor genesis raises questions as to whether experimental cancer-promoting mutations remain relevant to tumor maintenance. Utilizing a new doxycycline-inducible H-RASV12G INK4a null mouse melanoma model, we have shown that melanoma genesis and maintenance are strictly dependent upon H-RASV12G expression. Withdrawal of doxycycline and H-RASV12G down-regulation resulted in clinical and histological regression of primary and explanted tumors. Moreover, the initial stages of regression were highlighted by dramatic activation of apoptosis in the tumor cells as well as host-derived endothelial cells. These data provide genetic evidence that H-RASV12G plays a critical role in tumor maintenance and tumor angiogenesis.

BRG1, a component of the SWI-SNF complex, is mutated in multiple human tumor cell lines

Human BRG1 is a component of the evolutionarily conserved SWI-SNF chromatin remodeling complex. BRG1 has been implicated in growth control through its interaction with the tumor suppressor pRb and may consequently serve as a negative regulator of proliferation. Postulating that BRG1 may itself be a tumor suppressor gene, we screened a panel of tumor cell lines to determine whether the gene is targeted for mutation. We report that the COOH-terminal region of BRG1 is homozygously deleted in two carcinoma cell lines, prostate TSU-Pr1 and lung A-427. In addition, biallelic inactivations of BRG1 were observed in four other cell lines derived from carcinomas of the breast, lung, pancreas, and prostate; their mutations in BRG1 included three frameshift lesions and one nonsense lesion. Point mutations were also discovered in a number of other cell lines, however in most cases any effect of these mutations on BRG1 function remains to be established. A variety of different mutations within BRG1, in several cell lines, suggest that BRG1 may be targeted for disruption in human tumors. Significantly, reintroduction of BRG1 into cells lacking BRG1 expression was sufficient to reverse their transformed phenotype inducing growth arrest and a flattened morphology. These data strongly support the model that BRG1 may function as a tumor suppressor and strengthen the hypothesis that the regulation of gene expression through chromatin remodeling is critical for cancer progression. It will be important to confirm these observations in primary tumors.

Efficacy of mycophenolate mofetil in patients with diffuse proliferative lupus nephritis. Hong Kong-Guangzhou Nephrology Study Group

BACKGROUND

The combination of cyclophosphamide and prednisolone is effective for the treatment of severe lupus nephritis but has serious adverse effects. Whether mycophenolate mofetil can be substituted for cyclophosphamide is not known.

METHODS

In 42 patients with diffuse proliferative lupus nephritis we compared the efficacy and side effects of a regimen of prednisolone and mycophenolate mofetil given for 12 months with those of a regimen of prednisolone and cyclophosphamide given for 6 months, followed by prednisolone and azathioprine for 6 months. Complete remission was defined as a value for urinary protein excretion that was less than 0.3 g per 24 hours, with normal urinary sediment, a normal serum albumin concentration, and values for serum creatinine and creatinine clearance that were no more than 15 percent above the base-line values. Partial remission was defined as a value for urinary protein excretion that was between 0.3 and 2.9 g per 24 hours, with a serum albumin concentration of at least 30 g per liter.

RESULTS

Eighty-one percent of the 21 patients treated with mycophenolate mofetil and prednisolone (group 1) had a complete remission, and 14 percent had a partial remission, as compared with 76 percent and 14 percent, respectively, of the 21 patients treated with cyclophosphamide and prednisolone followed by azathioprine and prednisolone (group 2). The improvements in the degree of proteinuria and the serum albumin and creatinine concentrations were similar in the two groups. One patient in each group discontinued treatment because of side effects. Infections were noted in 19 percent of the patients in group 1 and in 33 percent of those in group 2 (P = 0.29). Other adverse effects occurred only in group 2; they included amenorrhea (in 23 percent of the patients), hair loss (19 percent), leukopenia (10 percent), and death (10 percent). The rates of relapse were 15 percent and 11 percent, respectively.

CONCLUSIONS

For the treatment of diffuse proliferative lupus nephritis, the combination of mycophenolate mofetil and prednisolone is as effective as a regimen of cyclophosphamide and prednisolone followed by azathioprine and prednisolone but is less toxic.

Hypoxia during upper gastrointestinal endoscopy with and without sedation and the effect of pre-oxygenation on oxygen saturation

In Study A, the incidence of arterial oxygen desaturation was studied using pulse oximetry (SaO2) in 100 sedated and 100 nonsedated patients breathing room air who underwent diagnostic upper gastrointestinal endoscopy. Hypoxia (SaO2 92% or less of at least 15 s duration) occurred in 17% and 6% of sedated patients and nonsedated patients, respectively (p < 0.03). Mild desaturation (SaO2 94% or less and less than 15 s duration) occurred in 47% of sedated patients compared with 12% of nonsedated patients (p < 0.001). In Study B, the effects of supplementary oxygen therapy and the effects of different pre-oxygenation times on arterial oxygen saturation (SaO2) in sedated patients were studied using pulse oximetry. One hundred and twenty patients who underwent diagnostic upper gastrointestinal endoscopy with intravenous sedation were studied. Patients were randomly allocated to one of four groups: Group A (n = 30) received no supplementary oxygen while Groups B-D received supplementary oxygen at 4 1 x min(-1) via nasal cannulae. The pre-oxygenation time in Group B (n = 30) was zero minutes, Group C (n = 30) was 2 min and Group D (n = 30) was 5 min before sedation and introduction of the endoscope. Hypoxia occurred in seven of the 30 patients in Group A and none in groups B, C and D (p < 0.001). We conclude that desaturation and hypoxia is common in patients undergoing upper gastrointestinal endoscopy with and without sedation. Sedation significantly increases the incidence of desaturation and hypoxia. Supplementary nasal oxygen at 4 1 x min(-1) in sedated patients abolishes desaturation and hypoxia. Pre-oxygenation confers no additional benefit.

Randomized prospective study of the effect of increased dialytic dose on nutritional and clinical outcome in continuous ambulatory peritoneal dialysis patients

Cohort studies have shown that greater urea (Kt/V) and creatinine clearances (CCr) were associated with better survival in patients on continuous ambulatory peritoneal dialysis (CAPD). The possibility of improved patient outcome with increased dialytic dose remains unknown. We prospectively studied over 1 year the effects of an extra 2-L bag on the outcome of 82 patients undergoing three daily 2-L exchanges for at least 12 months. At 1 year, 36 patients were undergoing 6-L exchanges, whereas 30 patients underwent 8-L exchanges. The increased dialytic dose resulted in increased total weekly Kt/V (TKt/V; 1.82 to 2.02), whereas total weekly CCr (TCCr) was maintained (63.2 to 61.9 L/1.73 m(2)). Control patients had reduced solute clearances (TKt/V, 1.87 to 1.67; TCCr, 64.8 to 54.6 L/1.73 m(2)). The fourth bag exchange resulted in a significant increase in net ultrafiltration (0.83 to 1.51 L/d), whereas the control group also had greater ultrafiltration (0.68 to 1.01 L/d) after 1 year. Although the normalized protein equivalent of nitrogen appearance (nPNA) was stable in the controls, the patients using 8-L exchanges achieved a greater nPNA (1.10 to 1.24 g/kg/d). There was no associated change in serum albumin levels (3.79 to 3.48 g/dL). The hospitalization rate increased in the controls (0.9 to 1.8 admissions/12 mon), whereas it was unchanged in the patients using 8-L exchanges. In conclusion, a 33% increase in dialytic prescription led to increased peritoneal and total clearances. Despite achieving increased nPNA (13%), the serum albumin level was unchanged. However, the increased hospitalization rate observed in the controls was avoided in the group using 8-L exchanges.

Conformational selection of inhibitors and substrates by proteolytic enzymes: implications for drug design and polypeptide processing

Inhibitors of proteolytic enzymes (proteases) are emerging as prospective treatments for diseases such as AIDS and viral infections, cancers, inflammatory disorders, and Alzheimer's disease. Generic approaches to the design of protease inhibitors are limited by the unpredictability of interactions between, and structural changes to, inhibitor and protease during binding. A computer analysis of superimposed crystal structures for 266 small molecule inhibitors bound to 48 proteases (16 aspartic, 17 serine, 8 cysteine, and 7 metallo) provides the first conclusive proof that inhibitors, including substrate analogues, commonly bind in an extended beta-strand conformation at the active sites of all these proteases. Representative superimposed structures are shown for (a) multiple inhibitors bound to a protease of each class, (b) single inhibitors each bound to multiple proteases, and (c) conformationally constrained inhibitors bound to proteases. Thus inhibitor/substrate conformation, rather than sequence/composition alone, influences protease recognition, and this has profound implications for inhibitor design. This conclusion is supported by NMR, CD, and binding studies for HIV-1 protease inhibitors/substrates which, when preorganized in an extended conformation, have significantly higher protease affinity. Recognition is dependent upon conformational equilibria since helical and turn peptide conformations are not processed by proteases. Conformational selection explains the resistance of folded/structured regions of proteins to proteolytic degradation, the susceptibility of denatured proteins to processing, and the higher affinity of conformationally constrained 'extended' inhibitors/substrates for proteases. Other approaches to extended inhibitor conformations should similarly lead to high-affinity binding to a protease.

Inferior limbal-conjunctival autograft transplantation for recurrent pterygium

PURPOSE

To study the safety and efficacy of inferior limbal-conjunctival autograft (LCAT) transplantation in the surgical management of recurrent pterygium.

METHODS

Prospective non-comparative case series. Inferior limbal-conjunctival autografting was performed on 11 patients (11 eyes) with recurrent pterygium. Pterygium recurrence was considered a surgical failure.

RESULTS

Recurrence of pterygium was noted in two (18.2%) eyes, after a mean follow up of 16.2 +/- 0.9 months (range: 10-19 months). Neither recurrence required further surgical treatment. Nonprogressive pseudopterygium formation was noted at the donor site in five (45.5%) eyes.

CONCLUSION

Inferior LCAT appears to be a safe and effective option in the management of recurrent pterygium. In patients with suspected or proven glaucoma, this may be the procedure of choice, if mitomycin C is contraindicated.

A retrospective study of seven cases of Candida parapsilosis peritonitis in CAPD patients: the therapeutic implications

BACKGROUND

Candida peritonitis accounts for the majority of fungal peritonitis in continuous ambulatory peritoneal dialysis (CAPD), but the Candida species were not routinely subtyped in previous studies. The clinical course and the outcome of Candida parapsilosis peritonitis remain unclear.

OBJECTIVE

To study the clinical course and outcome of C. parapsilosis peritonitis in CAPD patients.

SETTING

Peritoneal dialysis unit in a regional hospital.

PATIENTS AND DESIGN

A retrospective study on seven cases of C. parapsilosis peritonitis occurring in a single center over 3 years.

RESULTS

The 7 patients included 4 males and 3 females. Their mean age was 62 +/- 11.5 years. Two (29%) were diabetic. Three (43%) had a history of preceding peritonitis and 5 (71 %) had received broad spectrum antibiotic within the previous 1 month. All presented with cloudy dialysate, abdominal pain, and fever. The mean dialysate white cell count was 300 +/- 168/mm3 with a predominance of neutrophils (81.4% +/- 13.1%). The mean time from onset of symptoms to diagnosis was 5.7 +/- 3.1 days. All had been treated with immediate catheter removal within 24 hours of diagnosis and antifungal therapy, including oral fluconazole, intravenous (IV) amphotericin, or their sequential combination. Environmental samplings were negative for C. parapsilosis. The overall complication rate was exceptionally high (71%), with three (43%) complicated by abscess formation requiring surgical drainage, one peritoneal adhesion (14%), and one mortality (14%). In the end, only two (29%) could resume CAPD.

CONCLUSIONS

The outcome of this study group appeared worse than those previously described in the literature, and the optimal treatment for this group of patients remains unclear.

Genomic structure, chromosomal location, and mutation analysis of the human CDC14A gene

Human CDC14A is a dual-specificity phosphatase that shares sequence similarity with the recently identified tumor suppressor, MMAC1/PTEN/TEP1. By radiation hybrid mapping, we localized CDC14A to chromosome band 1p21, a region that has been shown to exhibit loss of heterozygosity in highly differentiated breast carcinoma and malignant mesothelioma. We have mapped the exon-intron structure of CDC14A gene and found an in-frame ATG at 14 codons upstream of the previously reported start site (GenBank Accession No. AF000367). In screening a panel of 136 cDNAs from tumor cell lines for coding mutations, we have identified a 48-bp in-frame deletion in the cDNA of the breast carcinoma cell line, MDA-MB-436. This deletion is the result of an acceptor splice site mutation (AG to AT) in intron 12 that causes the skipping of exon 13 in the gene. Loss of expression of the wildtype allele in the same breast cell line supports the possibility that CDC14A may be a tumor suppressor gene that is targeted for inactivation during tumorigenesis.

Development of C5a receptor antagonists

During host defense, the human complement system of plasma proteins initiates inflammatory and cellular immune responses to stimuli such as infectious organisms, chemical and physical injury, radiation and neoplasia. Elevated levels of one of these plasma proteins C5a, a 74 amino acid peptidic anaphylatoxin which is one of the most potent pro-inflammatory agents, correlate with the initiation and development of many inflammatory diseases. New agents which prevent binding of C5a to its G-protein-coupled receptors can inhibit the pro-inflammatory actions of C5a and thus be potentially used to treat chronic inflammatory disorders driven by complement activation and C5a production. In recent years significant progress has been made towards the development of potent antagonists of human C5a receptors and clinically useful compounds can reasonably be expected within the next few years.

Low-molecular-weight peptidic and cyclic antagonists of the receptor for the complement factor C5a

Activation of the human complement system of plasma proteins during immunological host defense can result in overproduction of potent proinflammatory peptides such as the anaphylatoxin C5a. Excessive levels of C5a are associated with numerous immunoinflammatory diseases, but there is as yet no clinically available antagonist to regulate the effects of C5a. We now describe a series of small molecules derived from the C-terminus of C5a, some of which are the most potent low-molecular-weight C5a receptor antagonists reported to date for the human polymorphonuclear leukocyte (PMN) C5a receptor. 1H NMR spectroscopy was used to determine solution structures for two cyclic antagonists and to indicate that antagonism is related to a turn conformation, which can be stabilized in cyclic molecules that are preorganized for receptor binding. While several cyclic derivatives were of similar antagonistic potency, the most potent antagonist was a hexapeptide-derived macrocycle AcF[OPdChaWR] with an IC50 = 20 nM against a maximal concentration of C5a (100 nM) on intact human PMNs. Such potent C5a antagonists may be useful probes to investigate the role of C5a in host defenses and to develop therapeutic agents for the treatment of many currently intractable inflammatory conditions.

Mediastinal bronchogenic cyst manifesting as a catastrophic myocardial infarction

Congenital bronchogenic cysts of the lung and mediastinum develop from the ventral foregut during embryogenesis. These cysts are often incidental radiologic findings in adults, but patients can be seen with symptoms of chest pain, cough, dyspnea, or any combination of these. Acute presentations are unusual and have rarely been reported. We present the unique case of a 36-year-old man seen with an acute coronary syndrome and sudden hemodynamic collapse. The patient sustained a massive and ultimately fatal myocardial infarction, compression of the left main coronary artery by a bronchogenic cyst was demonstrated at postmortem examination. If detected, bronchogenic cysts should be surgically excised to limit associated morbidity and mortality.

Multiple idiopathic left ventricular aneurysms in a Japanese woman

Idiopathic aneurysms of the left ventricle (LV) are uncommon in Western society. Multiple idiopathic LV aneurysms are distinctly unusual and are rarely reported. As with aneurysms of atherosclerotic origin, these entities may be associated with chest discomfort, congestive heart failure, cardiac dysrhythmias, and thromboembolic phenomena. We present the case of a Japanese woman living in the United States with chest discomfort, ventricular arrhythmias, and a previous transient ischemic attack who demonstrated four discrete LV aneurysms on ventriculography. Extensive evaluation demonstrated no clear cause for these aneurysms. The patient was treated conservatively with medical therapy and has continued to do well without adverse clinical sequelae.

Identification of the in vivo promoters of bacteriophages S13 and phi X174 and measurement of their relative activities

Regions of bacteriophages phi X174 and S13 that contain putative promoter sequences were amplified by the polymerase chain reaction (PCR) and cloned into the reporter vector pKO-1. Assays of galactokinase activity revealed in vivo promoter activity in those constructs containing the promoter sequences with transcription initiation (+1) sites at nucleotide positions 45, 982, 1823, and 5211. These were identical in location to sequences with in vitro promoter activity and to the three known promoters PA, PB, and PD. P5211 is the location of a new, fourth, promoter. A site with a +1 position at nucleotide 4876, previously shown to initiate RNA synthesis in an in vitro run-off transcription assay, had no in vivo promoter activity. To investigate whether flanking sequences had effects on promoter activity, restriction fragments of phi X174 and S13 that encompass the in vivo promoters were cloned into the reporter vector pKO-1. The PA and P5211 promoter constructs showed dramatic effects with increases in activity of up to 7 times that shown with the PCR-generated promoter constructs. The phi X174 PB promoter construct had a 50% decrease in activity compared with the PCR-generated PB clone. While the data showed that in most instances promoter activity is affected by the flanking sequences in which the promoter is embedded, no general pattern correlating flanking sequences and promoter activity could be discerned. Additional evidence that the promoter sequence regions were active in vivo promoters was obtained by S1 nuclease mapping experiments. Initiation of RNA synthesis was shown at positions 45, 982, and 5211.

Multicentre study of preoxygenation practices by anaesthesia providers

A total of 155 consecutive anaesthetics in three public Malaysian hospitals were prospectively studied to assess preoxygenation practices by their anaesthesia providers. Preoxygenation was practised in 96.1% of patients. Specialist and non-specialist anaesthesiologist did not preoxygenate 8.8% and 2.3% of their patients, respectively. Overall incidence of arterial oxygen desaturation during induction was 15.5%. Arterial oxygen desaturation occurred more frequently with emergency surgery (30.2%) in comparison to elective surgery (9.8%). Arterial oxygen desaturation occurred more frequently with non-specialist (18.9%) than specialist anaesthesia providers (3.0%).

Effects of a new C5a receptor antagonist on C5a- and endotoxin-induced neutropenia in the rat

A new C5a receptor antagonist, the cyclic peptide Phe-[Orn-Pro-D-cyclohexylalanine-Trp-Arg], (F-[OPdChaWR]), was tested for its ability to antagonize the neutropenic effects of both C5a and endotoxin in rats. Human recombinant C5a (2 microg kg(-1) i.v.) caused rapid neutropenia, characterized by an 83% decrease in circulating polymorphonuclear leukocytes (PMNs) at 5 min. Administration of F-[OPdChaWR] (0.3-3 mg kg(-1) i.v.), did not affect the levels of circulating PMNs but, when given 10 min prior to C5a, it inhibited the C5a-induced neutropenia by up to 70%. Administration of E. Coli lipopolysaccharide (LPS, 1 mg kg(-1) i.v.) also caused neutropenia with an 88% decrease in circulating PMNs after 30 min. When rats were pretreated with F-[OPdChaWR] (0.3 - 10 mg kg(-1) i.v.) 10 min prior to LPS, there was a dose-dependent antagonism of the neutropenia caused by LPS, with up to 69% reversal of neutropenia observed 30 min after LPS administration. These findings suggest that C5a receptor antagonists may have therapeutic potential in the many diseases known to involve either endotoxin or C5a.

Combined surgery for severe eye trauma with extensive iridodialysis, posterior lens dislocation, and intractable glaucoma

A 44-year-old woman sustained a severe left eye contusion from the explosion of a plastic bottle containing fermented orange juice. This resulted in extensive iridodialysis, posterior crystalline lens dislocation, and intractable glaucoma. Eleven days after the injury, combined surgery of trabeculectomy with mitomycin-C, pars plana vitrectomy, lens removal, iridodialysis repair, and scleral-fixated intraocular lens implantation under general anesthesia was performed. Intraocular pressure (IOP) was under control until 5 weeks postoperatively; glaucoma implant surgery was then performed. At the last follow-up 15 months after the combined surgery, best corrected visual acuity was 20/50 and IOP was 15 mm Hg without medication. Combined surgery can be considered a safe, effective option in the management of severe eye trauma in selected cases.

The use of combined intravenous pulse methylprednisolone and oral cyclosporin A in the treatment of corneal graft rejection: a preliminary study

PURPOSE

Oral cyclosporin A used in addition to high-dose intravenous pulse methylprednisolone has been shown to have an adjunctive effect in reversing the rejection of liver and renal transplants. The aim of this prospective study was to evaluate the benefits and risks of this combined drug therapy in acute corneal graft rejection.

METHODS

Eleven patients with acute corneal graft rejection received the combined regimen of a single pulse of intravenous methylprednisolone (500 mg) and a low dose of oral cyclosporin A (to maintain a trough blood level of 100-200 micrograms/l).

RESULTS

At a mean follow-up of 16.5 months (range 8-22 months) from the presentation of the graft rejection, reversal of graft rejection was achieved in 10 of 11 cases (90.9%). No recurrence of graft rejection was encountered during the study period. One patient developed a duodenal ulcer, which healed after medical treatment. No other complications were encountered.

CONCLUSIONS

The high efficacy and low risk of the combined regimen demonstrated in this preliminary study call for a larger-scale prospective double-masked study to confirm the value of this treatment protocol.

Characterization of a carboxy-terminal BRCA1 interacting protein

There are several lines of evidence indicating that the carboxy-terminal region of the tumor suppressor protein BRCA1 is a functionally significant domain. Using the yeast two-hybrid and in vitro biochemical assays, we show that a protein, CtIP, interacts specifically with the carboxy-terminal segment of human BRCA1 from residues 1602-1863. A germ line truncation mutation, Y1853ter, that removes the last 11 amino acids from the carboxy-terminus of BRCA1, abolishes not only its transcriptional activation function, but also binding to CtIP. The function of CtIP is unknown, but its reported association with a transcriptional repressor CtBP lends further support that it may have a role in transcription. A sequence based screen of a panel of 89 tumor cell line cDNAs for mutations in the CtIP coding region identified five missense variants. In the pancreatic carcinoma cell line, BxPC3, the non-conservative lysine to glutamic acid change at codon 337 is accompanied with apparent loss of heterozygosity or non-expression of the wild type allele. Thus it is plausible that CtIP may itself be a tumor suppressor acting in the same pathway as BRCA1.

Mycobacterium chelonei keratitis: report of a case and review of the literature

BACKGROUND

Mycobacterium (M) chelonei keratitis is a rare opportunistic eye infection that can cause significant morbidity when not being treated properly. The first case was documented by Gangadharam et al in 1978 and since then, a total of 49 cases were reported in the literature. One alarming fact is that more than 50% of cases were found in the Chinese population and mostly reported in recent years. The key to successful management of M. chelonei keratitis is early diagnosis by high index of suspicion. In order to alert ophthalmologists of this condition, we report a typical case of M. chelonei keratitis and review the literature of all the reported cases with special reference to its risk factors, treatments and outcome.

METHODS

The cases reported in the literature and a case of our own were reviewed and analyzed.

RESULTS

Our case was a 42-year-old gentleman who developed M. chelonei keratitis following pterygium surgery. He had typical clinical features of irregular infiltrates with radiating projections, indistinct fluffy lesion margins, satellite lesions and associated epithelial defect. Penetrating keratoplasty was performed after failed medical treatments. He recovered fully with a best corrected visual acuity (BCVA) of 20/30 at 24 months after the corneal transplant. A total of 49 cases were reported in the literature. The major risk factor was corneal injury, including surgical trauma. Corneal foreign bodies (24 cases, 48%) were found to be highly correlated, especially metallic foreign bodies (16 cases, 32%). Diagnosis was usually delayed for weeks or months and medical treatment alone often failed. Amikacin is usually the treatment of choice but its efficacy is just sub-optimal. Multi-resistance to the commonly used board spectrum antibiotics is not uncommon. The drug sensitivity test against atypical mycobacterium is technically difficult to perform and in vitro results are well known to be poorly related to clinical response. Combined extirpative keratectomy and topical antibiotics had been tried and was shown to be effective. Penetrating keratoplasty appeared to be a good definitive treatment for drug-resistance and advanced cases.

CONCLUSION

M. chelonei keratitis is a rare opportunistic infection. The major risk factor is eye injury, with foreign bodies or surgical trauma. Diagnosis is often missed and delayed as a result of its scarcity and variable presentations. High index of clinical suspicion with early diagnosis and prompt combined medical and surgical intervention seem to be the best measure to decrease ocular morbidity. Good alertness and knowledge of this condition would help our patients in the Far East as the literature review has shown a recent trend of increase in frequency and more than 50% of the reported cases come from the Chinese patients.

Small molecular probes for G-protein-coupled C5a receptors: conformationally constrained antagonists derived from the C terminus of the human plasma protein C5a

Activation of the human complement system of plasma proteins in response to infection or injury produces a 4-helix bundle glycoprotein (74 amino acids) known as C5a. C5a binds to G-protein-coupled receptors on cell surfaces triggering receptor-ligand internalization, signal transduction, and powerful inflammatory responses. Since excessive levels of C5a are associated with autoimmune and chronic inflammatory disorders, inhibitors of receptor activation may have therapeutic potential. We now report solution structures and receptor-binding and antagonist activities for some of the first small molecule antagonists of C5a derived from its hexapeptide C terminus. The antagonist NMe-Phe-Lys-Pro-D-Cha-Trp-D-Arg-CO2H (1) surprisingly shows an unusually well-defined solution structure as determined by 1H NMR spectroscopy. This is one of the smallest acyclic peptides found to possess a defined solution conformation, which can be explained by the constraining role of intramolecular hydrogen bonding. NOE and coupling constant data, slow deuterium exchange, and a low dependence on temperature for the chemical shift of the D-Cha-NH strongly indicate an inverse gamma turn stabilized by a D-Cha-NH. OC-Lys hydrogen bond. Smaller conformational populations are associated with a hydrogen bond between Trp-NH.OC-Lys, defining a type II beta turn distorted by the inverse gamma turn incorporated within it. An excellent correlation between receptor-affinity and antagonist activity is indicated for a limited set of synthetic peptides. Conversion of the C-terminal carboxylate of 1 to an amide decreases antagonist potency 5-fold, but potency is increased up to 10-fold over 1 if the amide bond is made between the C-terminal carboxylate and a Lys/Orn side chain to form a cyclic analogue. The solution structure of cycle 6 also shows gamma and beta turns; however, the latter occurs in a different position, and there are clear conformational changes in 6 vs 1 that result in enhanced activity. These results indicate that potent C5a antagonists can be developed by targeting site 2 alone of the C5a receptor and define a novel pharmacophore for developing powerful receptor probes or drug candidates.

Phacoemulsification, primary posterior capsulorhexis, and capsular intraocular lens implantation for uveitic cataract

PURPOSE

To evaluate the safety and efficacy of phacoemulsification, primary posterior capsulorhexis (PCCC), and primary intraocular lens (IOL) implantation for uveitic cataracts.

SETTING

Institutional practice.

METHODS

Fifteen consecutive eyes of 13 patients with various causes of uveitis received anterior capsulorhexis, phacoemulsification, PCCC, and in-the-bag implantation of a heparin-surface-modified IOL for visually disabling cataract. The safety and efficacy of the combined operation were studied prospectively.

RESULTS

At a mean follow-up of 16.9 months (range 8 to 30 months), all eyes had a clear central visual area. Fourteen of 15 eyes (93.3%) had good visual improvement after surgery. Eight eyes (53%) achieved a best corrected visual acuity (BCVA) of 20/30 or better and 6 (40%), 20/20 or better. Seventy-three percent of eyes attained a BCVA of 20/80 or better. The mean improvement in visual acuity was 5.2 Snellen lines (range 0 to 11 lines). No cases of uveitis flare-up or other major complications related to the cataract surgery occurred.

CONCLUSIONS

The study's preliminary results are encouraging and indicate that phacoemulsification, PCCC, and IOL implantation can be considered in patients with visually disabling uveitic cataract.

Rad52 associates with RPA and functions with rad55 and rad57 to assemble meiotic recombination complexes

We show that the Saccharomyces cerevisiae recombination protein Rad52 and the single-strand DNA-binding protein RPA assemble into cytologically detectable subnuclear complexes (foci) during meiotic recombination. Immunostaining shows extensive colocalization of Rad52 and RPA and more limited colocalization of Rad52 with the strand exchange protein Rad51. Rad52 and RPA foci are distinct from those formed by Rad51, and its meiosis-specific relative Dmc1, in that they are also detected in meiosis during replication. In addition, RPA foci are observed during mitotic S phase. Double-strand breaks (DSBs) promote formation of RPA, Rad52, and Rad51 foci. Mutants that lack Spo11, a protein required for DSB formation, are defective in focus formation, and this defect is suppressed by ionizing radiation in a dose-dependent manner. DSBs are not sufficient for the appearance of Rad51 foci; Rad52, Rad55, and Rad57 are also required supporting a model in which these three proteins promote meiotic recombination by promoting the assembly of strand exchange complexes.

A randomized prospective comparison of oral levofloxacin plus intraperitoneal (IP) vancomycin and IP netromycin plus IP vancomycin as primary treatment of peritonitis complicating CAPD

OBJECTIVE

To compare the therapeutic efficacy of daily oral levofloxacin plus intermittent intraperitoneal (IP) vancomycin (group 1) versus daily IP netromycin and intermittent IP vancomycin (group 2) in the primary treatment of peritonitis complicating continuous ambulatory peritoneal dialysis (CAPD).

DESIGN

A randomized multicenter prospective open-label comparative clinical study.

SETTING

University and Hospital Authority hospitals in Hong Kong.

PATIENTS

All CAPD patients who developed bacterial or culture-negative peritonitis beyond 28 days of a previous episode and without evidence of septicemia, associated tunnel infection, or known sensitivity to trial medications were accepted into the clinical trial.

RESULTS

A total of 101 patients entered the trial. The primary cure rate was 74.5% for group 1 and 73.6% for group 2. Baseline culture results appeared to influence the clinical outcome: the primary cure rate for culture-negative, gram-positive, and gram-negative episodes was 83.3%, 78.6%, and 42.9% for group 1 and 69.1%, 76.9%, and 71.3% for group 2, respectively. The primary cure rate also varied considerably among individual centers and was particularly noticeable in group 1. In the latter group, it correlated closely with in vitro levofloxacin resistance which in turn correlated closely with previous exposure to fluoroquinolones.

CONCLUSION

Oral levofloxacin in combination with intermittent IP vancomycin has comparable efficacy to IP netromycin combined with intermittent IP vancomycin as primary treatment in CAPD peritonitis, but is simpler and more cost-effective to administer. It may be recommended as primary therapy in centers with relatively low exposure and, therefore, low background resistance to fluoroquinolones.

Intraoperative mitomycin C to prevent recurrence of pterygium after excision: a 30-month follow-up study

OBJECTIVE

The purpose of the study was to examine the efficacy of intraoperative mitomycin C (MMC) in preventing recurrence of pterygium after excision and the postoperative complications encountered.

DESIGN

The study design was a prospective, randomized, clinical trial.

PARTICIPANTS

A total of 180 primary and recurrent pterygia were recruited for the study. They were randomized into five groups: A, control with no MMC; B, 0.02% MMC for 5 minutes; C, 0.04% MMC for 5 minutes; D, 0.02% MMC for 3 minutes; and E, 0.04% MMC for 3 minutes.

INTERVENTION

All patients received pterygium excision with or without the above four modes of intraoperative MMC application.

MAIN OUTCOME MEASURES

Recurrence of pterygium and postoperative complications such as superficial scleral melting were measured.

RESULTS

At a mean follow-up of 30 (groups A-C) and 20 months (groups D and E), the respective recurrence rates in groups A through E were 75%, 8.3%, 8.6%, 42.9%, and 22.9%. There were two cases of postoperative superficial scleral melting in group C. Otherwise, no major postoperative complications were encountered.

CONCLUSIONS

The midterm results of a single intraoperative application of MMC at the concentration of 0.02% for 5 minutes are encouraging. Its application as an adjunctive therapy for the surgical treatment of pterygium appeared to be safe and effective. However, because of the possibility of serious late complications, the authors suggest that this procedure be reserved for patients who have high probability of recurrence after excision of pterygium.

Successful treatment of IgA nephropathy in association with low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue type

Kidney and the urogenital tract are among the various mucosal sites involved in mucosa-associated lymphoid tissue (MALT) lymphoma. We report a case with simultaneous onset of crescentic immunoglobulin (Ig) A nephropathy and gastrointestinal low-grade B-cell lymphoma of the MALT type with kidney infiltration. M-component of IgM lambda was detected in the serum, and the renal biopsy specimen showed monotypic lambda light chain staining in the lymphoma cells but not the glomeruli. The heavy proteinuria and impaired creatinine clearance returned to normal, and microscopic hematuria disappeared 20 months after treatment with chlorambucil as single-agent chemotherapy. This coincided with a complete resolution of the gastric and renal lymphoma infiltration. The close association of both the onset and successful outcome of the two entities thus support their possible causal relationship, and we discuss the possibility of an association of the disturbance of the MALT by the lymphoma cells with the pathogenesis of IgA nephropathy.

Clinical profile of patients with late-onset SLE: not a benign subgroup

The onset of systemic lupus erythematosus (SLE) in later life has been associated with a benign clinical course and better prognosis compared with those with earlier onset. However, different reported studies have failed to agree on a distinct pattern of presentation. We retrospectively studied the clinical profile of a predominantly Chinese lupus population to review the behaviour of late-onset patients. Cumulative clinical features and laboratory findings in 102 patients with SLE were collected. Late-onset patients tended to have a less marked female predominance, a more insidious onset at presentation (P < 0.001), a decreased incidence of cutaneous lesions (P < 0.05), an increased occurrence of serositis (P = 0.004) and a lower cumulative number of SLE manifestations (P = 0.022) compared with the early-onset group. The incidences of all major organ involvement as well as the requirement of immunosuppressive therapies were similar in the two groups. Thus, in this study, late-onset SLE patients had a different clinical profile from the early-onset group, but did not constitute a benign subgroup of the lupus population.

Towards protein surface mimetics

Proteins are generally poor drug candidates due to bioavailability problems that stem from conformational instability, susceptibility to proteolytic degradation, poor membrane penetration, and unfavourable pharmacokinetics. Since many proteins exert their biological activity through relatively small regions of their folded surfaces, their actions could in principle be reproduced by much smaller designers molecules that retain these localised bioactive surfaces but have potentially improved pharmacokinetic/dynamic properties. Unlike proteins, smaller peptides generally lack well defined three dimensional structure in aqueous solution and tend to be conformationally mobile. Considerable progress has been made in recent years towards the use of molecular constraints to stabilise bioactive conformations. By affixing or incorporating templates that fix secondary and tertiary structures of small peptides, synthetic molecules (protein surface mimetics) can be devised to mimic the localised elements of protein structure that constitute bioactive surfaces. This is a promising growth area of medicinal chemistry that could impact significantly on biology and medicine. In this perspective review we summarise and prescribe methods for mimicking individual elements of secondary structure (helices, turns, strands, sheets) and for assembling their combinations into tertiary structures (helix bundles, multiple loops, helix-loop-helix motifs). A detailed understanding of the features that stabilise secondary and tertiary structures is the key to developing appropriate templates to support and correctly position residues in smaller folded surfaces. The goal is to direct critical amino acids (or surrogates) into the same conformational space and orientation as in bioactive surfaces of a native protein, yet retain sufficient flexibility to bind cooperatively, and with complementarity, to a given receptor. The requirements of size, shape, and directionality for templates to control peptide assembly and folding are discussed in relation to selected mimetics of secondary and tertiary structures. Particularly striking is the general tendency for protease inhibitors and MHC-binding peptides to adopt strand conformations; agonists and antagonists for G protein-coupled receptors to predominate in turn structures; transcription factors, cytokines and DNA/RNA-binding motifs to be helical; and antigen-recognition segments of antibodies to involve multiple loops.

Recombinant human erythropoietin (rHuEPO) therapy has no effect on peritoneal transport in CAPD patients: a short-term study

While theoretically the vasoconstriction associated with the rise in hemoglobin (Hb) level may potentially alter peritoneal transport characteristics, the effect of recombinant human erythropoietin (rHuEPO) therapy on peritoneal transport in continuous ambulatory peritoneal dialysis (CAPD) patients remains unclear. We have therefore performed a prospective study on the short-term effect of rHuEPO on the peritoneal transport characteristics in terms of the change in corrected dialysate/plasma creatinine (D/Pcr) in the fast peritoneal equilibration test (PET). Eight consecutive CAPD patients started on rHuEPO had fast PETs performed before and 4 to 6 months after the initiation of rHuEPO therapy. Another 8 CAPD patients with stable Hb levels not receiving rHuEPO served as a control group. All patients (study and control) had been on CAPD therapy for more than 3 months upon enrollment, and none had peritonitis during the study period. Patients receiving rHuEPO showed significant increase in Hb level, while the Hb levels of those in the control group remained unchanged. Neither the study nor the control group patients showed significant change in the corrected D/Pcr value over a mean observation period of 5.25 +/- 0.89 months. While rHuEPO appears to be effective in increasing the Hb level in CAPD patients, there is no significant impact on the corrected D/Pcr in the fast PET test observed in this short-term study.

RAD51 interacts with the evolutionarily conserved BRC motifs in the human breast cancer susceptibility gene brca2

Recent work has shown that the murine BRCA2 tumor suppressor protein interacts with the murine RAD51 protein. This interaction suggests that BRCA2 participates in DNA repair. Residues 3196-3232 of the murine BRCA2 protein were shown to be involved in this interaction. Here, we report the detailed mapping of additional domains that are involved in interactions between the human homologs of these two proteins. Through yeast two-hybrid and biochemical assays, we demonstrate that the RAD51 protein interacts specifically with the eight evolutionarily conserved BRC motifs encoded in exon 11 of brca2 and with a similar motif found in a Caenorhabditis elegans hypothetical protein. Deletion analysis demonstrates that residues 98-339 of human RAD51 interact with the 59-residue minimal region that is conserved in all BRC motifs. These data suggest that the BRC repeats function to bind RAD51.

A genetic algorithm for multiple molecular sequence alignment

MOTIVATION

Multiple molecular sequence alignment is among the most important and most challenging tasks in computational biology. The currently used alignment techniques are characterized by great computational complexity, which prevents their wider use. This research is aimed at developing a new technique for efficient multiple sequence alignment.

APPROACH

The new method is based on genetic algorithms. Genetic algorithms are stochastic approaches for efficient and robust searching. By converting biomolecular sequence alignment into a problem of searching for optimal or near-optimal points in an 'alignment space', a genetic algorithm can be used to find good alignments very efficiently.

RESULTS

Experiments on real data sets have shown that the average computing time of this technique may be two or three orders lower than that of a technique based on pairwise dynamic programming, while the alignment qualities are very similar.

AVAILABILITY

A C program on UNIX has been written to implement the technique. It is available on request from the authors.

Clinical predictors of non-diabetic renal disease in patients with non-insulin dependent diabetes mellitus

BACKGROUND

Several studies had suggested that non-diabetic renal disease (NDRD) was common among non-insulin dependent diabetes mellitus (NIDDM) patients with renal involvement.

METHODS

We prospectively studied the prevalence of NDRD among a Chinese NIDDM population. Renal biopsy specimens were evaluated with light-, immunohistological and electron-microscopy. The cohort consisted of 51 patients who had NIDDM and proteinuria > 1 g/24 h.

RESULTS

Patients with both isolated diabetic nephropathy (DN, n = 34) and NDRD (n = 17) had comparable duration of DM, creatinine clearance, serum creatinine, albumin and glycosylated haemoglobin levels, as well as incidences of retinopathy, neuropathy and hypertension. Significantly more patients with NDRD had microscopic haematuria (P = 0.043) or non-nephrotic proteinuria (P = 0.004). IgA nephropathy accounted for 59% of the NDRD identified.

CONCLUSIONS

In this study, microscopic haematuria and non-nephrotic proteinuria predicted the presence of NDRD among NIDDM patients presenting with renal disease.

Human mitogen-activated protein kinase kinase 4 as a candidate tumor suppressor

Mitogen-activated protein kinases function in signal transduction pathways that are involved in controlling key cellular processes in many organisms. A mammalian member of this kinase family, MKK4/JNKK1/SEK1, has been reported to link upstream MEKK1 to downstream stress-activated protein kinase/JNK1 and p38 mitogen-activated protein kinase. This mitogen-activated protein kinase pathway has been implicated in the signal transduction of cytokine- and stress-induced apoptosis in a variety of cell types. Here, we report that two human tumor cell lines, derived from pancreatic carcinoma and lung carcinoma, harbor homozygous deletions that eliminate coding portions of the MKK4 locus at 17p, located approximately 10 cM centromeric of p53. In addition, in a set of 88 human cancer cell lines prescreened for loss of heterozygosity, we detected two nonsense and three missense sequence variants of MKK4 in cancer cell lines derived from human pancreatic, breast, colon, and testis cells. In vitro biochemical assays revealed that, when stimulated by MEKK1, four of the five altered MKK4 proteins lacked the ability to phosphorylate stress-activated protein kinase. Thus, the incidence of coding mutations of MKK4 in the set of cell lines is 6 of 213 (approximately 3%). These findings suggest that MKK4 may function as a suppressor of tumorigenesis or metastasis in certain types of cells.