Interaction of Nucleoside Analogues with the Sodium–Nucleoside Transport System in Brush Border Membrane Vesicles from Human Kidney

The therapeutic efficacy of nucleosides and nucleoside analogues as antitumor, antiviral, antiparasitic, and antiarrhythmic agents has been well documented. Pharmacokinetic studies suggest that many of these compounds are actively transported in the kidney. The goal of this study was to determine if therapeutically relevant nucleosides or analogues interact with the recently characterized Na⁺-driven nucleoside transport system of the brush border membrane of the human kidney. Brush border membrane vesicles (BBMV) were prepared from human kidney by divalent cation precipitation and differential centrifugation. The initial Na⁺-driven ³H-uridine uptake into vesicles was determined by rapid filtration. The effect of several naturally occurring nucleosides (cytidine, thymidine, adenosine), a pyrimidine base (uracil), a nucleotide (UMP), and several synthetic nucleoside analogues [zidovudine (AZT), cytarabine (Ara-C), and dideoxycytidine (ddC)] on Na⁺–uridine transport was determined. At a concentration of 100 µM the naturally occurring nucleosides, uracil, and UMP significantly inhibited Na+-uridine transport, whereas the three synthetic nucleoside analogues did not. Adenosine competitively inhibited Na+-uridine uptake with a K _i of 26.4 µM (determined by constructing a Dixon plot). These data suggest that naturally occurring nucleosides are substrates of the Na⁺–nucleoside transport system in the renal brush border membrane, whereas synthetic nucleoside analogues with modifications on the ribose ring are not. The K _i of adenosine is higher than clinically observed concentrations and suggests that the system may play a physiologic role in the disposition of this nucleoside.     

Comparison of sodium amylosulfate and sodium polyanetholsulfonate in blood culture media.

A comparison between sodium polyanetholsulfonate and sodium amylosulfate in unvented vacuum blood culture bottles containing tryptic soy broth was made with 5,800 sets of blood cultures. No statistically significant differences in isolation rates of bacteria were noted.     

结核性淋巴结炎的“结节病”样变型

对１２例经病理学专家会诊、从病变上认定的淋巴结“结节病”石蜡包埋组织，应用结核杆菌ＤＮＡ特异性序列片段的聚合酶链反应（Ｍ．ＴＢ－ＰＣＲ）技术、ＢＣＧ免疫组化（ＢＣＧ－ＩＨＣ）技术和抗酸染色（ＡＦ）进行了分支杆菌／结核杆菌检测。在这１２例考虑为“结节病”的病例中：有１例呈ＢＣＧ－ＩＨＣ和Ｍ。ＴＢ－ＰＣＲ两项阳性；另１例呈ＡＦ、ＢＣＧ－ＩＨＣ和Ｍ．ＴＢ－ＰＣＲ三项阳性。研究结果提示：（１）某些结核性淋巴结炎可呈结节病样病变；（２）淋巴结结节病很可能与分支杆菌／结核杆菌感染有关。     

Evaluation of BBL crystal MRSA ID system.

The BBL Crystal system (Becton Dickinson Microbiology Systems, Cockeysville, Md.) was evaluated for its accuracy in identifying oxacillin resistance in Staphylococcus aureus by testing of mec-specific-gene-positive and -negative isolates. Although the manufacturer makes no claim for use of the product for testing of staphylococci other than S. aureus, the product's potential utility in detecting oxacillin resistance in isolates of mec gene-positive and -negative Staphylococcus epidermidis was also explored. All mec gene-negative staphylococci yielded a negative MRSA ID test reaction. There was a close correlation between mec gene positivity and a positive reaction in the methicillin-resistant S. aureus identification system with 63 of 69 (91%) stock isolates of S. aureus yielding a positive result in 4 h, 66 of 69 (95%) yielding a positive result in 5 h, and 68 of 69 (99%) yielding a positive result in 6 h. The corresponding percentage agreements at 4, 5, and 6 h for mec gene-positive stock isolates of S. epidermidis were 87, 91, and 96%, respectively.     

Comparison of isolation of Haemophilus vaginalis (Corynebacterium vaginale) from peptone-starch-dextrose agar and Columbia colistin-nalidoxic acid agar.

A total of 447 cervical or vaginal specimens were inoculated in parallel onto peptone-starch-dextrose (PSD) and Columbia colistin (10 mg/ml)-nalidixic acid (15 mug/ml) (CNA) agar and were incubated for 48 h at 35 degrees C in an atmosphere with 2 to 10% CO2. One hundred (22.4%) of the cultures were positive for Haemophilus vaginalis. Forty-eight of the isolates were recovered from both PSD and Columbia CNA agar, five from PSD only, and 47 from Columbia CNA agar only (P less than 0.001). On Columbia CNA agar, 76 of the isolates were detected after 24 h of incubation, and the remainder were detected within 4 days of incubation.     

Microbiological and clinical evaluation of the isolator lysis-centrifugation blood culture tube.

In a controlled evaluation of 6,010 blood cultures, the yield of clinically significant microorganisms was greater from a lysis-centrifugation system (Isolator, Du Pont Co.) than from a nonvented vacuum bottle containing tryptic soy broth with sodium polyanetholesulfonate and CO2 and a vented bottle containing biphasic brain heart infusion medium with sodium polyanetholesulfonate. The Isolator significantly increased the frequency of isolation of Staphylococcus aureus and Candida spp. and significantly decreased the time required for the detection of S. aureus, Pseudomonas aeruginosa, and Candida spp.; however, anaerobic bacteria were recovered significantly more frequently from nonvented bottles with tryptic soy broth, and pneumococci were recovered significantly more frequently from both bottle systems. Contamination of cultures was significantly greater with the Isolator system than with either bottle system. Regardless of the number of blood cultures obtained per septic episode, the Isolator detected microbiologically proven bacteremia or fungemia in a significantly greater number of patients and significantly decreased the time required for detection.     

Multicenter clinical laboratory evaluation of a beta-lactamase disk assay employing a novel chromogenic cephalosporin, S1.

S1, a new chromogenic cephalosporin (International BioClinical, Inc., Portland, Oreg.), was used to detect beta-lactamase production among a variety of commonly encountered bacteria in a four-center collaborative study. Results of an S1 disk assay were compared with those obtained by a nitrocefin-based disk procedure (Cefinase; Becton-Dickinson Microbiology Systems, Cockeysville, Md.), with repetitive testing of five quality control organisms and with individual tests of recent clinical isolates of Neisseria gonorrhoeae (162 strains), Haemophilus influenzae (162 strains), Moraxella catarrhalis (155 strains), Staphylococcus aureus (161 strains), and Bacteroides fragilis (164 strains). The performances of the two beta-lactamase disk assays were comparable for the first three species cited above. However, the S1 assay appeared to be a more sensitive procedure than the Cefinase assay when applied to S. aureus and B. fragilis, with respect to both total numbers of positive results and length of time to a definitive positive endpoint.     

Protective efficacy in chickens, geese and ducks of an H5N1-inactivated vaccine developed by reverse genetics

We generated a high-growth H5N1/PR8 virus by plasmid-based reverse genetics. The virulence associated multiple basic amino acids of the HA gene were removed, and the resulting virus is attenuated for chickens and chicken eggs. A formalin-inactivated oil-emulsion vaccine was prepared from this virus. When SPF chickens were inoculated with 0.3 ml of the vaccine, the hemagglutinin-inhibition (HI) antibody became detectable at 1 week post-vaccination (p.v.) and reached a peak of 10log2 at 6 weeks p.v. then slowly declined to 4log2 at 43 weeks p.v. Challenge studies performed at 2, 3 and 43 weeks p.v. indicated that all of the chickens were completely protected from disease signs and death. Ducks and geese were completely protected from highly pathogenic H5N1 virus challenge 3 weeks p.v. The duration of protective immunity in ducks and geese was investigated by detecting the HI antibody of the field vaccinated birds, and the results indicated that 3 doses of the vaccine inoculation in geese could induce a 34 weeks protection, while 2 doses induced more than 52 weeks protection in ducks. We first reported that an oil-emulsion inactivated vaccine derived from a high-growth H5N1 vaccine induced approximately 10 months of protective immunity in chickens and demonstrated that the oil-emulsion inactivated avian influenza vaccine is immunogenic for geese and ducks. These results provide useful information for the application of vaccines to the control of H5N1 avian influenza in poultry, including chickens and domestic waterfowl.     

Effects of atmosphere of incubation and of routine subcultures on detection of bacteremia in vacuum blood culture bottles.

Studies comparing isolation rates of bacteria and yeasts from vented and unvented vacuum blood culture bottles containing soybean-casein digest broth showed significantly more frequent and more rapid recovery of Candida and Pseudomonas from the vented bottle and no other statistically significant differences between the two. Subculture of bottles on the day of their collection was shown to accelerate recovery of 48% of positive cultures by day 1. A second subculture of known positive cultures yielded additional organisms in 1.5% of cultures.     

Comparison of immunohistochemical markers in the differential diagnosis of adrenocortical tumors: immunohistochemical analysis of adrenocortical tumors.

Most adrenocortical tumors (ACTs) can be diagnosed directly by a combination of morphologic features and clinical findings. However, sometimes it may be difficult to distinguish ACTs from other neoplasms such as pheochromocytomas and some metastatic tumors, particularly for small biopsy specimens because they may be morphologically similar. Expression of calretinin has recently been suggested as a valuable immunomarker for the differential diagnosis between ACTs and other tumors; however, its diagnostic value is still under debate. To determine the diagnostic value of calretinin in Chinese patients with adrenocortical and non-ACTs, we employed both polyclonal and monoclonal anticalretinin to characterize the expression of calretinin in adrenal tissues and compared its expression with that of inhibin alpha, Melan-A, cytokeratin, or CD99 by immunohistochemistry in tissue microarrays and standard tissue sections of 414 specimens. Our results revealed that calretinin was expressed by adrenocortical cells, but not by the other cells tested and the percentage of calretinin-positive ACTs reached 99% when stained with polyclonal antibodies, which was higher than that with monoclonal anticalretinin (91.3%), anti-Melan-A (90.3%), antiinhibin alpha (81.6%). In addition, our results also revealed that ACTs were stained by cytokeratin (AE1/AE3) with variable degrees (58.7%). Furthermore, unlike anti-Melan-A that stained all metastatic malignant melanoma, anticalretinin did not recognize other tested tumors. Therefore, immunohistologic staining with polyclonal anticalretinin is more sensitive than other antibodies tested for the diagnosis of ACTs. However, monoclonal anticalretinin appeared to be more specific. Importantly, our data suggested that the fried-egg-like staining pattern, but not the mere cytoplasmic staining, was characteristic of anticalretinin staining in adrenocortical tissues. Notably, a few anticalretinin negative-ACTs were stained by other immunomarkers that we tested. Thus, the combinational characterization of calretinin (either by polyclonal or monoclonal antibody), inhibin alpha, and Melan-A expression is of great significance in the differential diagnosis of ACTs.