Characterization of multidrug resistance by fluorescent dyes

Fluorimetric techniques were used to examine accumulation of fluorescent probes by the P388 murine leukemia and an anthracycline-resistant subline, P388/Adriamycin(ADR), which expresses the multidrug-resistant phenotype. P388 could be differentiated from P388/ADR on the basis of fluorescence intensity measurements using 3 classes of cationic dyes that are sensitive to membrane potential differences: rhodamine esters, cyanines, and styrylpyridinium dyes. But fluorescence intensity differences were also observed with potential-insensitive dyes: zwitterionic rhodamines and an acridine orange derivative. In all cases, fluorescence intensity differences were caused by impaired dye accumulation, and could be eliminated by treatment of P388/ADR cells with verapamil. Moreover, fluorescence signals from 2 anionic potential-sensitive dyes, merocyanine 540 and a bis-oxonol, were identical in P388 and P388/ADR. None of these dyes could be used to delineate CCRF-CEM, a lymphoblastic leukemia of human origin from the CEM/VM-1 subline that exhibits a markedly atypical drug resistance pattern not based on an enhanced outward transport. But accumulation of both neutral and cationic dyes was impaired in CEM/VLB100, a subline of CCRF-CEM expressing mdr. These studies show that many cationic and neutral fluorescent probes are substrates for the enhanced outward drug transport system associated with P388/ADR cells, and cannot be used to probe membrane-potential differences in cells expressing the mdr phenotype. With several dyes, differences in fluorescence intensity were sufficient so that flow cytometry could be used to delineate P388 from P388/ADR and CCRF-CEM from CEM-VLB100. The latter technique may be useful for identifying malignant cell populations expressing multidrug resistance in patients with neoplastic disease.     

Monoclonal antibodies specific for Corynebacterium sepedonicum, the causative agent of potato ring rot

BALB/c mice were immunized with Corynebacterium sepedonicum, and spleen cells from the immunized animals were fused with cells of the mouse myeloma line P3-X63-Ag8.653. Several hybridoma cell cultures were selected for further study. Monoclonal CS-B-5 was specific for C. sepedonicum and did not react significantly with other closely related phytopathogenic corynebacteria in an enzyme-linked immunosorbent assay (ELISA). As few as 10(3) organisms could be detected. This approach should prove useful for developing improved diagnostic procedures for a number of bacterial plant pathogens.     

Serial incontinence assessment in elderly inpatient men

Urinary incontinence is a major problem for elderly chronic care patients. As a consequence, a high level of nursing care is required for patient management. Because incontinence rehabilitation programs are usually implemented during the day shift, the incidence of incontinence according to time of day has major implications regarding patient management. Although treatment is usually based on severity, assessment of incontinence severity in elderly chronic care inpatients is difficult. In this study, a telemetric incontinence detection system was developed to identify incontinence episodes. An absorbent pad exchange technique was used for incontinence volume measurement. The study group, 66 chronic care inpatient men over 65 years old, were subject to incontinence measurements over 10 days during all nursing shifts using the telemetric incontinence detection system. The results showed a significantly high incidence of incontinence episodes during the evening nursing shift. The volume of involuntary urine loss was significantly higher during the night nursing shift. Thus, the highest level of incontinence severity occurred during the time of day when nursing staff on chronic care units is usually the lowest.     

Cost implications of new treatments for advanced colorectal cancer

BACKGROUND:

Since 1996, 6 new drugs have been introduced for the treatment of metastatic colorectal cancer. Although they are promising, these drugs frequently are given in the palliative and are much more expensive than older treatments. The objective of the current study was to measure the cost implications of treatment with sequential regimens that include chemotherapy and/or monoclonal antibodies.

METHODS:

A Markov model was used to evaluate a hypothetical cohort of 1000 patients with newly diagnosed, metastatic colorectal cancer. Patients supposedly received up to 3 lines of treatment before supportive care and subsequent death. Data were obtained from published, multicenter phase 2 and randomized phase 3 clinical trials. Sensitivity analyses were conducted on the efficacy, toxicity, and cost.

RESULTS:

Using drug costs alone, treatment that included new chemotherapeutic agents increased survival at an incremental cost‐effectiveness ratio (ICER) of $100,000 per discounted life‐year (DLY). The addition of monoclonal antibodies improved survival at an ICER of >$170,000 per DLY. The results were most sensitive to changes in the initial regimen. Even with significant improvements in clinical characteristics (efficacy and toxicity), treatment with the most effective regimens still had very high ICERs.

CONCLUSIONS:

Treatment of metastatic colorectal cancer with the most effective regimens came at very high incremental costs. The authors concluded that cost‐effectiveness analyses should be a routine component of the drug‐development process, so that physicians and patients are informed appropriately regarding the value of new innovations. Cancer 2009. © 2009 American Cancer Society.     

The effects of tifluadom and ketazocine on behaviour, dopamine turnover in the basal ganglia and local cerebral glucose utilization of rats

The purpose of the present study was to evaluate the interrelation between behavioural effects of kappa-opiates and cerebral neurochemical correlates in rats. Administration of the kappa-opiates tifluadom (2.5 mg/kg i.p.) or ketazocine (5 mg/kg i.p.) caused a marked initial decrease in locomotor activity lasting about 15-20 min, followed by an increase in locomotor activity at about 40 min after drug administration. At 15 min after i.p. injections of the same drugs 3,4-dihydroxyphenylacetic acid concentrations, measured by HPLC, were slightly increased in the nucleus accumbens, but unchanged in the striatum; dopamine concentrations were unchanged in both regions. The rates of glucose utilization, determined by quantitative [14C]2-deoxyglucose autoradiography, were mainly unchanged except for the nucleus accumbens, which showed an increased glucose utilization after both drugs given i.v. Tifluadom also decreased rates of glucose utilization in the caudate nucleus and parietal, sensorimotor, olfactory and frontal cortices. The above-mentioned effects on behaviour and local cerebral glucose utilization could be prevented by naloxone (3 mg/kg). The data suggest that changes in locomotor activity, neurotransmitter metabolism and neuronal activity in the nucleus accumbens are interrelated and that opiate-induced akinesia is mediated via the nucleus accumbens.     

Candidates for the Certificate of Added Qualifications in Geriatric Medicine. Who, why, and when?

We surveyed physicians who took the examination for certification for Added Qualifications in Geriatric Medicine, physicians who only inquired about the examination, and physicians who expressed no interest in the examination to learn about practice characteristics of those who took the examination and their reasons for taking it. Based on a 72% response rate, we were able to demonstrate that those who took the examination took care of an older population of patients and disproportionately more of the oldest-old. These physicians were more likely to report the care of older people to be a professional focus and, in internal medicine, were more likely to have had formal training in geriatrics. Their reasons for taking the examination were primarily to obtain credentials but also frequently to improve their ability to care for older people. Nearly two-thirds of those who had inquired about the exam but did not take it in 1988 plan to do so at a later date.     

Electromagnetic phased arrays for regional hyperthermia: optimal frequency and antenna arrangement.

This paper investigates the effects of the three-dimensional arrangement of antennae and frequency on temperature distributions that can be achieved in regional hyperthermia using an electromagnetic phased array. It compares the results of power-based and temperature-based optimization. Thus, one is able to explain the discrepancies between previous studies favouring more antenna rings on the one hand and more antennae per ring on the other hand. The sensitivity of the results is analysed with respect to changes in amplitudes and phases, as well as patient position. This analysis can be used for different purposes. First, it provides additional criteria for selecting the optimal frequency. Secondly, it can be used for specifying the required phase and amplitude accuracy for a real phased array system. Furthermore, it may serve as a basis for technological developments in order to reduce both types of sensitivities described above.     

In vitro evaluation of microcrystalline chitosan (MCCh) as gel-forming excipient in matrix granules.

Although much research has been carried out into the effects of chitosan and its chemical properties on drug release, less attention has been paid to the effects of its physical properties. The aim of this study was to characterize microcrystalline chitosan (MCCh) as a gel-forming excipient. Matrix granules containing chitosans of differing physicochemical properties (crystallinity, molecular weight, degree of deacetylation) and ibuprofen or paracetamol as model drugs were prepared. Gel formation by the chitosans in the granules and subsequent effects on drug release were studied at pH 1.2 and pH 5.8. The chitosan granules acted as slow-release formulations in the case of ibuprofen (a class-II drug in the Biopharmaceutics Classification System) but with paracetamol (class-I) no controlled-release formulation could be developed. Microcrystalline grades of chitosan had the most marked retardant effects on drug release, with the efficacy of gel formation by MCCh explaining the results. The kinetic constant for ibuprofen release (at pH 5.8) ranged from 22%.h(-1) (MCCh) to 31%.h(-1) (unmodified chitosan). The release rate was easily controlled by varying the amount or molecular weight of MCCh, and to a lesser extent by the degree of deacetylation. The effects were most pronounced when pH was markedly acidic, suggesting that MCCh granules might be particularly useful in preparing stomach-specific slow-release dosage forms.