小檗碱对局灶性脑缺血大鼠血小板聚集及血浆TXB2和6－keto－PGF1a水平的影响

以大鼠可逆性大脑中动脉梗塞（ＭＣＡＯ）致局灶性脑缺血为模型，观察小檗碱对大鼠ＭＣＡＯ２４ｈ后血小板粘附、聚集、血栓形成及血浆ＴＸＢ２和ＰＧＩ２生成的影响。结果表明，小檗碱２０ｍｇ·ｋｇ－１·ｄ－１ｉｐｌ，３或５ｄ，明显降低ＭＣＡｏ２４ｈ后血小板粘附性及ＡＤＰ、胶原和花生四烯酸诱导的血小板聚集率，抑制血浆ＴＸＢ２水平。同剂量ｉｐ３或５ｄ，则抑制血栓形成。提示小檗碱可能通过其抗血小板粘附和聚集及影响花生四烯酸代谢而发挥抗脑缺血作用。     

Bone regeneration at extraction sockets filled with leukocyte-platelet-rich fibrin: An experimental pre-clinical study

Background We aimed to histomorphometrically evaluate the effects of Leucocyte-Platelet-Rich Fibrin (L-PRF), with and without the combination of a bone grafting material, for alveolar ridge preservation using an in vivo canine model.Material and Methods Seven dogs (Female Beagles, ~18-month-old) were acquired for the study. L-PRF was prepared from each individual animal by drawing venous blood and spinning them through a centrifuge at 408 RCF-clot (IntrasSpin, Intra-Lock, Boca Raton, FL). L-PRF membranes were obtained from XPression fabrication kit (Biohorizons Implant Systems, Inc., AL, USA). A split mouth approach was adopted with the first molar mesial and distal socket defects treated in an interpolated fashion of the following study groups: 1) Empty socket (negative control); 2) OSS filled defect 3) L-PRF membrane; and 4) Mix of Bio-Oss® with L-PRF. After six weeks, samples were harvested, histologically processed, and evaluated for bone area fraction occupancy (BAFO), vertical/horizontal ridge dimensions (VRD and HRD, respectively), and area of coronal soft tissue infiltration.Results BAFO was statistically lower for the control group in comparison to all treatment groups. Defects treated with Bio-Oss® were not statistically different then defects treated solely with L-PRF. Collapsed across all groups, L-PRF exhibited higher degrees of BAFO than groups without L-PRF. Defects filled with Bio-Oss® and Bio-Oss® with L-PRF demonstrated greater maintenance of VRD relative to the control group. Collapsed across all groups, Bio-Oss® maintained the VRD and resulted in less area of coronal soft tissue infiltration compared to the empty defect. Soft tissue infiltration observed at the coronal area was not statistically different among defects filled with L-PRF, Bio-Oss®, and Bio-Oss® with L-PRF.Conclusions Inclusion of L-PRF to particulate xenograft did not promote additional bone heading at 6 weeks in vivo. However, we noted that L-PRF alone promoted alveolar socket regeneration to levels comparable to particulate xenografts, suggesting its potential utilization for socket preservation. Key words:L-PRF, bone healing, socket preservation.     

Bacteremia due to obligate anaerobes following large bowel surgery in a tertiary care hospital in South India

In view of the rising incidence of Anaerobic bacteremia(AB), the use of anaerobic blood culture bottles have been recommended in addition to the aerobic blood culture bottles. The need to perform antimicrobial susceptibility testing(AST) for anaerobes has become mandatory owing to increasing metronidazole resistance. The frequency of AB following large bowel surgery and the metronidazole susceptibility for members of the Bacteroides fragilis group were determined. The incidence of AB was found to be 16%. Seventeen obligate anaerobes were isolated in total, of which B. fragilis was the most common. Two of twelve isolates of B. fragilis were resistant to metronidazole.     

The anti-protozoal drug pentamidine blocks KIR2.x-mediated inward rectifier current by entering the cytoplasmic pore region of the channel

Background and purpose:

Pentamidine is a drug used in treatment of protozoal infections. Pentamidine treatment may cause sudden cardiac death by provoking cardiac arrhythmias associated with QTc prolongation and U-wave alterations. This proarrhythmic effect was linked to inhibition of hERG trafficking, but not to acute block of ion channels contributing to the action potential. Because the U-wave has been linked to the cardiac inward rectifier current (I_K1), we examined the action and mechanism of pentamidine-mediated I_K1 block.

Experimental approach:

Patch clamp measurements of I_K1 were made on cultured adult canine ventricular cardiomyocytes, K_IR2.1-HEK293 cells and K_IR2.x inside-out patches. Pentamidine binding to cytoplasmic amino acid residues of K_IR2.1 channels was studied by molecular modelling.

Key results:

Pentamidine application (24 h) decreased I_K1 in cultured canine cardiomyocytes and K_IR2.1-HEK293 cells under whole cell clamp conditions. Pentamidine inhibited I_K1 in K_IR2.1-HEK293 cells 10 min after application. When applied to the cytoplasmic side under inside-out patch clamp conditions, pentamidine block of I_K1 was acute (IC₅₀= 0.17 µM). Molecular modelling predicted pentamidine-channel interactions in the cytoplasmic pore region of K_IR2.1 at amino acids E224, D259 and E299. Mutation of these conserved residues to alanine reduced pentamidine block of I_K1. Block was independent of the presence of spermine. K_IR2.2, and K_IR2.3 based I_K1 was also sensitive to pentamidine blockade.

Conclusions and implications:

Pentamidine inhibits cardiac I_K1 by interacting with three negatively charged amino acids in the cytoplasmic pore region. Our findings may provide new insights for development of specific I_K1 blocking compounds.     

EFFECT OF SUBCLINICAL LEAD INTOXICATION ON LARYNGEAL CANCER

SUMMARY In this study we investigated the possible relationship of laryngeal cancer and subclinical lead intoxication, using the depression of aminolevulinic acid dehydratase (ALAD) activity in blood as indicator. Twenty-six patients with laryngeal cancer and 53 normal controls met the criteria to enter the study. Blood ALAD activity values in the patients with laryngeal cancer ranged from 27.1 to 75.3 U/l with a mean of 50.79 U/l. The respective values in the control group ranged from 36.2 to 98 U/l with a mean of 59.76 U/l. There was a statistically significant difference between the two means (0.001 <p<0.01), whereas blood lead concentrations in all patients were within normal limits. These findings support the hypothesis that low level lead intoxication (subclinical blood lead levels), from cars, industries and products, may contribute to the risk of laryngeal cancer. Further investigation is needed to clarify the exact relationship between lead and cancer of the larynx.     

Evaluation of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid in the inhibition of rouleaux formation

BACKGROUND: DIDS (4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid) inhibits the formation of serum-or plasma-induced rouleaux through its ability to bind to band 3 on red cell membranes. This property of DIDS was evaluated in the serologic testing of specimens exhibiting rouleaux. STUDY DESIGN and METHODS: Optimal test conditions for DIDS treatment of reagent red cells were determined by varying the volume and concentration of DIDS solution and the incubation temperature and duration and comparing the results of antibody screening procedures using specimens that exhibit macroscopically visible rouleaux. Blind titration studies compared untreated and DIDS-treated red cells to evaluate the maintenance of antigen integrity. The use of DIDS-treated red cells for antibody detection and identification was evaluated by comparing the results in donor specimens containing antibodies with those in untreated and DIDS-treated selected panel cells. In addition, 4-percent (wt/vol) dextran in serum was used to induce rouleaux formation as a way of determining the capability of DIDS to resolve ABO serum grouping discrepancies. RESULTS: Complete inhibition of rouleaux formation occurred when reagent red cells were treated by incubation at 37 degrees C for 10 minutes with 150 microliter (approx. 5 drops) of 0.05 mg per mL of DIDS in 0.9-percent NaCl. There were no significant differences in titration scores of untreated and DIDS-treated red cells tested with the 19 antisera used to assess antigen integrity. Antibody identification studies showed that DIDS-treated reagent red cells reacted similarly to untreated reagent red cells. In addition, DIDS resolved dextran-induced ABO serum grouping discrepancies. CONCLUSION: DIDS effectively resolved the serologic problems associated with the presence of rouleaux, without affecting the results of the test system itself. Implementation of this method to inhibit the rouleaux-forming properties of serum and plasma specimens can be useful in serologic testing.     

Therapeutic immunization against Helicobacter mustelae in naturally infected ferrets

BACKGROUND & AIMS: Helicobacter infection of the gastric antrum is responsible for a number of gastric disorders. Antibiotic therapy is lengthy and is not always effective. It has been shown previously that oral immunization against Helicobacter felis in mice can prevent colonization after challenge. The aim of this study was to investigate the efficacy of therapeutic immunization in eradicating an established Helicobacter infection and in reducing gastritis. METHODS: Domestic ferrets, confirmed to be infected with Helicobacter mustelae by gastric endoscopy, were orally immunized with varying doses of purified Helicobacter pylori urease in combination with the mucosal adjuvant cholera toxin. Ferrets were assessed 1 week and 6 weeks after treatment for infection and pathology. RESULTS: Therapeutic immunization eradicated Helicobacter colonization in 30% of all immunized ferrets, although there was no difference in efficacy between the varying doses of antigen tested. The difference was statistically significant when compared with animals administered cholera toxin alone or buffer (P = 0.04). The intensity of inflammation was also significantly reduced in immunized animals (P = 0.0003). CONCLUSIONS: Oral immunization with purified H. pylori urease and cholera toxin can eradicate H. mustelae in a natural host pathogen model. Oral immunization of chronically infected animals markedly reduced gastric inflammation. (Gastroenterology 1996 Jun;110(6):1770-5)