Radioreceptor Assay of Metoprolol in Human Plasma: Comparison with an Enantiospecific High-Performance Liquid Chromatographic (HPLC) Procedure

Plasma concentrations of metoprolol after acute and repetitive administration of R/S-metoprolol to healthy volunteers were measured by a -adrenoceptor subtype-specific radioreceptor assay (RRA) and by an enantiospecific high-performance liquid chromatographic (HPLC) method. In the RRA, R/S-metoprolol showed a 20-fold ₁-subtype selectivity: the S-( – )-enantiomer was 35-fold more potent than the R-( + )-enantiomer. A comparison between S-( – )-metoprolol concentrations detected in the plasma samples by HPLC and those detected by RRA yielded a 1/1 relationship, indicating that active metabolites are not present to a significant extent. These results were independent of the widely scattering metabolic clearance of metoprolol (with the potential of differences in the rate and extent of formation of active metabolites) in the volunteers. In general, HPLC methods can be validated by comparison with RRA in order to clarify whether active metabolites are present and—on the basis of the K_i value from RRA—whether the detection limit of the physicochemical procedure is sufficient to cover the therapeutically relevant range.     

Effect of dipyridamole on fluorodeoxyuridine cytotoxicity in vitro and in cancer patients

Summary Dipyridamole (DP) has previously been studied both in vitro and in vivo in combination with various antimetabolites, including methotrexate and 5-fluorouracil (5FU). We evaluated in vitro and clinically the effects of adding DP to fluorodeoxyuridine (FUDR) in colorectal cancer. Using a human colony-forming assay, we observed that 0.05 M DP increased the cytotoxicity of FUDR by a median of 33.5-fold vs 1.5-fold for 5FU against human colon-cancer cell lines. The mechanism of the DP-enhanced antitumor activity of FUDR is not completely understood but appears to be related to a profound inhibition by DP of thymidine accumulation in and FUDR efflux from colon-cancer cell lines. On the basis of these in vitro results, 28 patients with metastatic colon cancer were entered in a clinical trial of monthly courses of 0.1 mg/kg FUDR daily for 14 days and 75 mg oral DP 5 times daily for 14 days starting on the 3rd day of continuous i.v. FUDR infusion. The pharmacokinetics of DP was studied in three patients; the results showed that 98% of total serum DP was protein-bound and that free DP levels were significantly lower than the concentrations necessary for the expected in vitro DP/FUDR modulation. Treatment was well tolerated, with only 12 patients developing mild to moderate toxicity. Of 27 evaluable patients, 4 achieved a partial response that lasted 2, 3, 5, and 6+ months. This relatively low response rate (15%), which is similar to that achieved with FUDR alone, may be explained by the low steady-state plasma concentrations of free DP achieved in our patients. Other means of DP administration, such as i.v., i.a., and i.p. injection, may be required to achieve free DP concentrations necessary for successful biochemical modulation of FUDR in patients.Supported in part by grants CA17094, CA23074, and CA39629 from the National Institutes of Health, Bethesda, Md 20205, and a grant from the Arizona Chronic Disease Commission. HSG is a recipient of an American Cancer Society Career Development Award     

Detailed gene copy number and RNA expression analysis of the 17q12-23 region in primary breast cancers

Chromosome region 17q12-23 commonly shows an increase in DNA copy number in breast cancers, suggesting that several oncogenes are located at this site. We performed a high-resolution expression array and comparative genomic hybridization analysis of genes mapped to the entire 17q12-23 region, to identify novel candidate oncogenes. We identified 24 genes that showed significant overexpression in breast cancers with gain of 17q12-23, compared to cancers without gain. These genes included previously identified oncogenes, together with several novel candidate oncogenes. FISH analysis using specific gene probes hybridized to tissue arrays confirmed the underlying amplification of overexpressed genes. This high-resolution analysis of the 17q12-23 region indicates that several established and novel candidate oncogenes, including a Wnt-signaling pathway member, are amplified and overexpressed within individual primary breast cancer samples. We were also able to confirm the presence of two apparently separate and reciprocally amplified groups of genes within this region. Investigation of these genes and their functional interactions will facilitate our understanding of breast oncogenesis and optimal management of this disease.     

Role of RNA and protein in memory storage: A review

The literature on the possible role of RNA and protein in long-term memory is reviewed in terms of the following five criteria: (1) The molecule should have a defined role in normal brain function. (2) There should be a quantitative and/or qualitative change in the molecule as a function of learning. (3) The molecule should lead to some type of relatively permanent change in the functioning of the brain. (4) Altered synthesis or utilization of the molecule should lead to predictable consequences for memory. (5) The localization of the response should be consistent in terms of the utilization of that portion of the brain in the particular task.     

Enhanced cerebrovascular permeability by Metrazol: significance for brain metastases

Metrazol enhanced the penetration of two proteins (¹²⁵I human serum albumin and horseradish peroxidase), and the anticancer agent, razoxane, into the central nervous system of anaesthetized rats. Penetration was increased throughout the whole brain. With the exception of the bladder, no peripheral tissue was affected. The increase in brain permeability was temporary and reversed within 4 hours; brain levels of drug and protein were increased by up to three times.[/p]     

Patients with erythrophobia (fear of blushing) show abnormal autonomic regulation in mental stress conditions

OBJECTIVE: The objective of this study was to analyze the autonomic functions of patients with erythrophobia. METHODS: Forty patients with a diagnosis of erythrophobia (female/male ratio 18/22) without any other organic lesions and 20 healthy volunteers (female/male ratio 10/10) were assessed. Clinical evaluation was performed using a modified version of semistructured interviews. Autonomic testing was performed by means of spectral analysis of heart rate and continuous blood pressure by sparse discrete Fourier transformation at rest and under mental stress. RESULTS: There were no significant difference between the two samples in age, sex distribution, BMI, resting systolic, or diastolic blood pressure, nor was there a difference in autonomic baseline functioning between the 40 patients with erythrophobia and the control subjects. On the other hand, patients with erythrophobia consistently showed higher pulse rates (88 +/- 20 vs. 78 +/- 9 bpm, p <.05), higher total heart rate power values (8.40 +/- 0.63 vs. 8.07 +/- 1.02 p <.05), higher midfrequency spectral values (7.38 +/- 0.66 vs. 7.02 +/- 1.18, p <.01), higher high-frequency spectral values (6.89 +/- 0.86 vs. 6.48 +/- 1.44, p <.05), and lower baroreceptor sensitivity (8.62 +/- 8.16 vs. 11.65 +/- 4.42, p <.005) than the healthy subjects. ANOVA showed a significant group interaction (p <.0001) between the samples. CONCLUSIONS: This study provides evidence for abnormal autonomic functioning in patients with erythrophobia when under mental stress.     

Evaluation of a new cellulose sponge-tipped swab for microbiological sampling: a laboratory and clinical investigation

A new type of swab (Cellswab; Cellomeda, Turku, Finland), utilizing a highly absorbent cellulose viscose sponge material, was compared to some traditional swabs. The survival of 14 aerobic and 10 anaerobic and microaerophilic bacterial species in the Cellswab, two commercial swab transport systems (Copan, Brescia, Italy, and Orion Diagnostica, Espoo, Finland), and one Dacron swab (Technical Service Consultants Ltd. [TSC], Heywood, United Kingdom) was evaluated. Bacteria were suspended in broth, into which the swabs were dipped. The Cellswab absorbed 1.3 times more fluid and released 3.5 times more fluid upon plating than the other swabs. Aerobic bacteria were stored in dry tubes, the others in transport medium, at 4 degrees C and room temperature (RT), for up to 14 days. Swab samples were transferred to plates at 0, 1, 2, 4, 7, and 14 days. For 10 strains the Cellswab yielded > or =10% of the original CFU for longer than all the other swabs. In the clinical study, the ability of the Cellswab to detect beta-hemolytic streptococci from throat samples (n = 995) was compared to that of the TSC Dacron swab. The swabs performed equally, both when their samples were transferred to plates immediately and after storage for 1 day at 4 degrees C or RT. The changes in normal microbiota after storage were also similar. The Cellswab was found to perform at least as well as ordinary swabs. It was better at storing fastidious strains, and at keeping bacteria viable for long storage times; it might well be a useful replacement or complement to ordinary swabs.     

Antitumour effect of RA 233 alone and combined with radiotherapy

The effect of RA233 alone or in combination with radiation was investigated in vivo on the S180 sarcoma, the B16 melanoma and the Lewis lung carcinoma. The combined treatment was a significant improvement over radiation alone for the B16 and S180 tumours. RA233 alone did not influence the growth of these tumours. When the primary 3LL was irradiated, tumour size was unaffected but the number of pulmonary metastases was reduced. They were further reduced by the combination of RA233 and radiation. The number, volume and cytokinetics of the B16 cells and the 3LL cells were affected to varying degrees by RA233. The significance of these changes relative to the effects of RA233 are discussed.