Treatment of hyperhomocysteinemia in renal transplant recipients. A randomized, placebo-controlled trial

BACKGROUND: Stable renal transplant recipients have an excess prevalence of hyperhomocysteinemia, which is a risk factor for arteriosclerosis. OBJECTIVE: To determine the effect of treatment with 1) vitamin B6 or 2) folic acid plus vitamin B12 on fasting and post-methionine-loading plasma total homocysteine levels in renal transplant recipients. DESIGN: Block-randomized, placebo-controlled, 2 x 2 factorial study. SETTING: University-affiliated transplantation program. PATIENTS: 29 clinically stable renal transplant recipients. INTERVENTION: Patients were randomly assigned to one of four regimens: placebo (n = 8); vitamin B6, 50 mg/d (n = 7); folic acid, 5 mg/d, and vitamin B12, 0.4 mg/d (n = 7); or vitamin B6, 50 mg/d, folic acid, 5 mg/d, and vitamin B12, 0.4 mg/d (n = 7). MEASUREMENTS: Fasting and 2-hour post-methionine-loading plasma total homocysteine levels. RESULTS: Vitamin B6 treatment resulted in a 22.1% reduction in geometric-mean post-methionine-loading increases in plasma total homocysteine levels (P = 0.042), and folic acid plus vitamin B12 treatment caused a 26.2% reduction in geometric-mean fasting plasma total homocysteine levels (P = 0.027). These results occurred after adjustment for age; sex; and pretreatment levels of total homocysteine, B vitamins, and creatinine. CONCLUSIONS: Vitamin B6 should be added to the combination of folic acid and vitamin B12 for effective reduction of both post-methionine-loading and fasting plasma total homocysteine levels in renal transplant recipients.     

Direct analysis of protein mixtures by tandem mass spectrometry

Methods to identify proteins contained in mixtures are described. The approach uses microcolumn liquid chromatography and automated tandem mass spectrometry in conjunction with protein and nucleotide database searching algorithms. This approach is applied to the identification of proteins obtained by immunoprecipitation reactions, interaction with a GST protein fusion products and interaction with a macromolecular complex.     

Performance of four computer-based diagnostic systems

BACKGROUND: Computer-based diagnostic systems are available commercially, but there has been limited evaluation of their performance. We assessed the diagnostic capabilities of four internal medicine diagnostic systems: Dxplain, Iliad, Meditel, and QMR. METHODS: Ten expert clinicians created a set of 105 diagnostically challenging clinical case summaries involving actual patients. Clinical data were entered into each program with the vocabulary provided by the program's developer. Each of the systems produced a ranked list of possible diagnoses for each patient, as did the group of experts. We calculated scores on several performance measures for each computer program. RESULTS: No single computer program scored better than the others on all performance measures. Among all cases and all programs, the proportion of correct diagnoses ranged from 0.52 to 0.71, and the mean proportion of relevant diagnoses ranged from 0.19 to 0.37. On average, less than half the diagnoses on the experts' original list of reasonable diagnoses were suggested by any of the programs. However, each program suggested an average of approximately two additional diagnoses per case that the experts found relevant but had not originally considered. CONCLUSIONS: The results provide a profile of the strengths and limitations of these computer programs. The programs should be used by physicians who can identify and use the relevant information and ignore the irrelevant information that can be produced.     

Detection of immunoglobulin M antibodies to glycoprotein G-2 by western blot (immunoblot) for diagnosis of initial herpes simplex virus type 2 genital infections

Western blots (immunoblots) for the detection of immunoglobulin M (IgM) antibodies specific for herpes simplex virus type 1 (HSV-1) and HSV-2 in patients' sera were developed. The locations of the type-specific glycoprotein G (gpG-2) of HSV-2 (92- and 140-kDa forms) and glycoprotein C of HSV-1 (gpC-1), which carries mostly type-specific antigenic epitopes, were checked with specific monoclonal antibodies. Western blot assays for IgM antibody to gpC-1 or gpG-2 were performed after depletion of IgG by precipitation with anti-human IgG. In patients with primary HSV-2 genital infections, seroconversion of IgM and IgG antibodies to both the 92- and 140-kDa forms of gpG-2 was observed, although both antibodies appeared in convalescent-phase serum after the first week. IgM and IgG antibodies to low-molecular-size polypeptides (40 to 65 kDa) were the first antibodies observed in patients with primary infection, but these antibodies were cross-reactive with HSV-1 and HSV-2. However, in patients with recurrent HSV-2 infections, IgG antibodies to both forms of gpG-2 and the low-molecular-size polypeptides were found no matter how early after onset the patient was bled, and IgM to gpG-2 did not appear. In patients with nonprimary initial genital HSV-2 infections, IgG antibody to HSV-1 was demonstrated in the first serum specimen, and HSV-2-specific IgM was found in 39% of the serum specimens. Hence, the Western blot assay can be used to test for IgM antibody to gpG-2, allowing for the retrospective diagnosis of inital HSV-2 infections and its use as a supplementary test to the gpG-2 IgG enzyme-linked immunosorbent assays developed elsewhere. In contrast, IgM antibody to gpG-2 is not usually detected in patients with recurrent HSV-2 infections.     

Epidemiological aspects of inflammatory bowel disease in a north Italian population: a 4-year prospective study

OBJECTIVE: To determine the incidence and clinical characteristics at presentation of inflammatory bowel disease (IBD) in a defined area of north Italy. DESIGN: A 4-year prospective population-based epidemiological study. SETTING: An area in Lombardia defined by the National Health Service scheme with about 294,000 inhabitants, two referral hospitals and 259 general practitioners (GPs). PATIENTS: Subjects presenting to a GP with symptoms compatible with IBD underwent a diagnostic work-up at one of the referral hospitals. Those with ulcerative colitis (UC), Crohn's disease (CD) or indeterminate colitis diagnosed according to a defined protocol were included, as were residents of the area with IBD diagnosed elsewhere. Rigid case ascertainment methods were used. Patients were followed for one year; 125 patients were identified. RESULTS: The patient ascertainment rate was constant over the 4 years; UC was diagnosed in 82 patients, CD in 40, and indeterminate colitis in three. The mean annual incidence of IBD for the whole period was 10.6/10(5) inhabitants (95% confidence limits, 7.2-15.1), 7.0/10(5) for UC (4.3-10.7) and 3.4/10(5) (1.6-6.3) for CD. The mean interval between onset of symptoms and diagnosis was under 6 months. The clinical characteristics of our patients were similar to those of north European and American series. CONCLUSION: The incidence of IBD was higher than previously observed in Italy but was still lower than in some north European countries and in the USA. Our data could be used as a basis for future longitudinal studies and in international comparative investigations.     

An inexpensive infrared growth sensor array for detection of bacterial antibiotic susceptibility

An inexpensive infrared sensor was constructed and used for the rapid testing of bacterial antibiotic susceptibility by detection of changes in absorbance at 950 nm. By comparing cultures of clinical isolates together with control strains (Escherichia coli NCTC 10418, Staphylococcus aureus NCTC 6571 or Pseudomonas aeruginosa NCTC 10662) after addition of an antibiotic, results on susceptibility were obtained within 3-5 h from the original plate culture. Representative strains of E. coli, P. aeruginosa, and S. aureus were tested successfully against ampicillin, penicillin, gentamicin or ciprofloxacin.     

Proteolytic cleavage of p53: a model for the activation of p53 in response to DNA damage

p53 is a multifunctional protein that reacts to DNA damage within the cell and regulates the cell growth arrest and/ or apoptotic pathways. However, the mechanism of p53 activation in response to DNA damage is unknown. Recently we have shown that interaction of p53 with sites of DNA damage induces selective proteolytic cleavage of p53, resulting in fragments of 40 and 35 kDa molecular weight. We have also shown that interaction of p53 with single-stranded (ss)DNAs results in a different pattern of selective proteolysis. This interaction gives a novel of 50-kDa protein generated by C-terminal cleavage of the full length protein and released from the p53-ssDNA complexes. Here we discuss a model where p53 responds to the DNA damage by generating different sets of the proteolytic fragments according to the type of the damage.     

Structure-based discovery of ligands targeted to the RNA double helix

Ligands capable of specific recognition of RNA structures are of interest in terms of the principles of molecular recognition as well as potential chemotherapeutic applications. We have approached the problem of identifying small molecules with binding specificity for the RNA double helix through application of the DOCK program [Kuntz, I. D., Meng, E. C., and Shoichet, B. K. (1994) Acc. Chem. Res. 27, 117-123], a structure-based method for drug discovery. A series of lead compounds was generated through a database search for ligands with shape complementarity to the RNA deep major groove. Compounds were then evaluated with regard to their fit into the minor groove of B DNA. Those compounds predicted to have an optimal fit to the RNA groove and strong discrimination against DNA were examined experimentally. Of the 11 compounds tested, 3, all aminoglycosides, exhibited pronounced stabilization of RNA duplexes against thermal denaturation with only marginal effects on DNA duplexes. One compound, lividomycin, was examined further, and shown to facilitate the ethanol-induced B to A transition in calf thymus DNA. Fluorine NMR solvent isotope shift measurements on RNA duplexes containing 5-fluorouracil provided evidence that lividomycin binds in the RNA major groove. Taken together, these results indicate that lividomycin recognizes the general features of the A conformation of nucleic acids through deep groove binding, confirming the predictions of our DOCK analysis. This approach may be of general utility for identifying ligands possessing specificity for additional RNA structures as well as other nucleic acid structural motifs.