High-performance liquid chromatography of HIV protease inhibitors in human biological matrices

Methods for HPLC analysis of protease inhibitors (PIs) in human biological matrices were reviewed. Assays have been developed for analysis of single PIs or for simultaneous measurement of multiple PIs in plasma-serum, saliva, cerebrospinal fluid and semen. Liquid-liquid extraction was most often applied for sample pretreatment, but solid-phase extraction and protein precipitation were used as well. Reversed-phase or ion-pair chromatography have been used to separate PIs. Detection of PIs should be sensitive enough for quantitation of plasma concentrations below trough levels of single PIs, or below proposed therapeutic thresholds for PIs. The large majority of assays employs UV detection. As the potential for interferences is large, the selectivity of every method should be evaluated properly. The available high-performance liquid chromatography (HPLC) methods have been applied in clinical pharmacokinetic studies and for therapeutic drug monitoring of PIs. Participation in an interlaboratory quality control program is recommended for every laboratory engaged in the bioanalysis of PIs.     

Food granules elicit heavy drinking in polydipsic rats independently of meal duration.

Excessive drinking, in rats made polydipsic on intermittent delivery of food pellets, is inversely related to the time the rat spends with its head in the feeder, early in the interfood interval. In a sensitization model, this explains why food textures that induce more oral activity, e.g., powder, do not elicit drinking. This hypothesis was examined by coding the behavior of polydipsic rats and varying the duration of the meal delivered in each interval, while holding texture constant. Polydipsic rats were presented with pellets, food granules, or food powder. The food granules were dispensed over periods lasting 1, 14, 21, and 28 s. All food deliveries were of the same mass. The food was delivered periodically at 60-s intervals in each condition. The 14 rats in the experiment served as their own controls by experiencing every condition. The food granule conditions induced the expected increases in feeding early in the interval. However, instead of progressively reducing drinking, the excessive drinking simply occurred later in the interval. By contrast, the powder condition resulted in the immediate elimination of polydipsia. The results suggest that food texture elicits excessive drinking independently of temporal factors and that elicitation of the sensitized drinking response must depend on other factors.     

Telomerase in Cancer Diagnosis and Therapy

Curing cancers is one of the most challenging tasks of modern medicine. The major problem is the heterogeneity of human tumours and thus finding a 'universal' target for cancer treatment. The discovery that the expression of the enzyme telomerase is a hallmark of immortality and cancer, and that it is found in the majority (>85%) of human tumours but is repressed in most normal cells, has therefore caused considerable excitement. These observations led to the design of potential telomerase inhibitors and ideas about targeting telomerase in the clinic. To date, several classes of telomerase inhibitory agents have been identified and are in preclinical development. However, the approach has not yet been tested clinically. Because of the proposed function of telomerase, and the understanding that replicative cell senescence or cell death result from progressive telomere shortening during successive cell divisions, even complete enzyme inhibition will not produce immediate cell death. Designing clinical trials for promising telomerase inhibitors requires consideration of the novel mechanism of action of these drugs. A lag period between initiation of treatment and occurrence of effects is likely, and thus anti-telomerase therapy might best be given in adjuvant treatment protocols after initial tumour debulking therapy and in combination with other cytostatic agents. The available knowledge of telomerase biology and its association with human tumours suggests that telomerase inhibition might prove a valuable addition to current cancer treatment regimens.     

Normal and tumor-bearing host macrophage responses: variability in accessory function, surface markers, and cell-cycle kinetics.

Normal and tumor-bearing host (TBH) peritoneal macrophage (M phi) responses to in vitro lipopolysaccharide (LPS) treatment were measured by assessing functional and phenotypic changes. Both normal and TBH untreated M phi suppressed mixed lymphocyte reaction (MLR) reactivity at all concentrations. Normal host M phi treated with LPS for 3 h were suppressive at all concentrations. TBH M phi treated with LPS for 3 h were not suppressive in the MLR until more than 5% were added. Surprisingly, 24 h treatment of normal and TBH M phi with LPS induced cells that significantly enhanced MLR reactivity when added at 2% or 5%. These cells were not suppressive until a 20% M phi concentration was reached. LPS treatment of normal and TBH M phi changed the percentage of cells expressing the surface markers Mac-1, -2, -3, and Ia as determined by flow cytometry. Normal host peritoneal M phi treated with LPS for 3 h had decreased Mac-1 and -3 expression, but there was no change in Mac-2 or Ia. Plating for 24 h did not change the percentage of M phi expressing Mac-1, -3, or Ia but did cause an increase in Mac-2+ M phi. Treatment of normal host M phi with LPS for 24 h led to a decrease in Mac-1+ and Ia+ M phi, no change in Mac-3+ M phi, but an increase in Mac-2+ M phi. LPS treatment of TBH M phi for 3 h decreased the number of Mac-1+ M phi, but Mac-2+, -3+, or Ia+ M phi numbers did not change. Plating TBH M phi for 24 h caused a decrease in the number of Mac-1+ M phi, no change in Mac-3+ or Ia+ M phi, but an increase in Mac-2+ M phi. Treatment with LPS for 24 h led to no change in the number of Mac-1+, -3+, or Ia+ TBH M phi, but Mac-2+ M phi increased. The phenotypic and functional changes after LPS treatment led us to ask if these changes were detectable at the level of DNA and RNA. Flow cytometric analysis of acridine orange-stained M phi was used to measure DNA and RNA levels. This analysis determines M phi cell-cycle kinetics and estimates their RNA synthesis. In normal host M phi, a 3-h LPS treatment caused a decrease of cells in G0/G1 but an insignificant change in RNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

CD4+ helper T cell depression in autism

CD4+ (helper) T cells are a heterogenous population of lymphocytes including at least two distinct subpopulations. To investigate the possibility that immune abnormalities in some subjects with autism may involve abnormal distributions of CD4+ and/or CD8+ cells, (suppressor) T cells, peripheral blood lymphocytes of 25 autistic subjects were characterized with monoclonal antibodies and flow cytometry. The autistic subjects had a significantly lower percentage and number of CD4+ cells, a lower number of T cells (CD2+ cells) and B cells (CD20+ cells), and a lower percentage and number of total lymphocytes than siblings and normal subjects. The level of blood values for female subjects appeared lower than those for males as compared to normal subjects of the same sex. These results suggest that a decrease in CD4+ cells is associated with autism.     

Reactivity of European and American isolates of Borrelia burgdorferi with different monoclonal antibodies by means of a microimmunoblot technique

Ten European and 3 North American isolates of Borrelia burgdorferi were compared as to their reactivity with 9 mouse monoclonal antibodies (MMA) to the type strain B. burgdorferi B31, and 1 MMA directed against B. hermsii. A Treponema pallidum strain was used for a genus-specific control. Differences in the protein patterns of the European and the North American strains were mostly based on the absence of distinct OspA and OspB bands. The OspA MMAs H 5332 and H 3TS were reactive with 3 European and the 3 North American strains. H 5332 alone reacted with another 3 strains from Europe, the remaining 4 were not recognized by one of the OspA MMAs. OspB MMAs showed reactivity with 3 European and the 3 North American strains. Of the flagella antibodies MMA H 9724 and H 604 reacted with all strains, whereas H 6TS reacted just with 2 each of the European and North American strains. There was no reactivity at all with the B. hermsii monoclonal H 9E11. No MMA reacted with the T. pallidum strain. According to a proposal for a serotyping system based upon major surface proteins of B. burgdorferi by A. G. Barbour, 6 of the strains investigated belong to serotype I, 3 to serotype II, and 4 to serotype III. Reactivity with 4 MMAs to OspB allowed to establish 5 subtypes. The geographical origin of the strains seems to be in relation with respective subtypes, an observation which needs to be substantiated for a larger group of strains. The microimmunoblot technique proved to be a useful tool which saves material and time and yields reproducible results.     

Molecular interactions of Leishmania promastigote surface protease with human alpha 2-macroglobulin

The interaction of Leishmania promastigote surface protease (PSP) with the plasmatic protease inhibitor alpha 2-macroglobulin (alpha 2M) was investigated. In plasma, solubilized PSP forms covalent complexes only with alpha 2M, at the exclusion of other protease inhibitors. The formation of complexes is accompanied by the proteolytic cleavage of the alpha 2M subunit and by the transition from the 'slow' to the 'fast' form of alpha 2M. The proteolytic activity of solubilized PSP on azocasein is inhibited by alpha 2M. In contrast, we found no evidence for a specific interaction of alpha 2M with the surface of promastigotes and PSP proteolytic activity on intact cells was not inhibited by alpha 2M.     

Angiogenic activity in injured rat corneas as assayed on the chick chorioallantoic membrane

The temporal appearance of an angiogenic effect in chemically cauterized rat corneas was determined by studying the responses that they induced in the vessels of the chick chorioallantoic membrane (CAM). Injured rat corneas were grafted to the CAM from 90 minutes to 7 days after cautery. As controls, uninjured rat corneas and corneas of healthy rats cauterized immediately after death were also grafted. The vascular responses to the grafts were graded in a masked fashion by stereoscopic biomicroscopy on a five-tiered scale, by evaluations of projected colored photographs on the same scale, and by histologic examination of the grafts. Separate coefficients of angiogenesis were determined for the stereoscopic and photographic evaluations. We detected significant differences between corneas of healthy rats that were uninjured or cauterized chemically immediately after death and those that were cauterized in the living rat. Uninjured corneas and corneas cauterized postmortem elicited a mild vascular response in the CAM, as reflected by low coefficients of angiogenesis. Whereas blood vessels were not detected in corneas injured postmortem, some normal corneas vascularized but only after being on the CAM for at least 7 days. The coefficients of angiogenesis of corneas that were cauterized during life were significantly higher than those of both control groups prior to grafting after comparable times on the CAM. Corneas vascularized on the CAM included those that were cauterized as soon as 90 minutes prior to grafting. The strongest vascular responses, as reflected by coefficient of angiogenesis and the frequency of histologically confirmed nucleated avian erythrocytes within intracorneal blood vessels, were found with corneas that were grafted to the CAM 3 days after chemical cauterization. Corneas that vascularized on the CAM were associated with a prominent leukocytic infiltrate suggestively derived from the chick embryo. The results suggest that chemically cauterized rat corneas contain a chemoattractant for polymorphonuclear leukocytes within 90 minutes of injury and that such polymorphonuclear leukocytes or other components of the injured corneas possess the ability to stimulate angiogenesis on the CAM.     

PMN chemotactic factor produced by glass-adherent cells in the acute inflammation caused by Paracoccidioides brasiliensis

Intraperitoneal inoculation of BIO.A mice with P. brasiliensis induces an acute inflammatory infiltrate in which 40-50% of the cells are PMN leucocytes. Previous depletion of serotonin, prostaglandin, histamine and complement does not alter the course of inflammation. Complement-derived factors appear to have no active participation in the process since C5-deficient mice depleted or not by Cobra venom factor (CoF) show the same kind of cellular influx. On the other hand, peritoneal cells incubated (6 h) with the fungus release a soluble factor that induces in vivo an active chemotaxis of PMN cells when inoculated i.p. The factor has the following characteristics: a) it is produced by adherent cells; b) it is protein in nature; c) its production is inhibited by incubation of peritoneal cells with 10 micrograms/ml puromycin and d) it has a molecular weight less than 15 000 daltons, as determined by gel filtration through a Sephadex G-75 column.