Differential responses of human tumor-cells to polyunsaturated Fatty-acids - stimulation of proliferation of a colon-tumor cell-line by docosahexaenoic Acid

The potential differential effects of polyunsaturated fatty acids (5-100 mu g/ml) on four human tumour cell lines of different origin and a human fibroblast cell line were investigated. Following 6 days exposure to the fatty acids, gamma linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid, culture growth was almost completely abolished at the highest concentration used. At lower concentrations, the tumour cell lines exhibited a differential sensitivity to the inhibitory effects of the fatty acids on cell number (IC50, breast=lung>melanoma>colon). MRC-5 fibroblast cell numbers were significantly increased at low concentrations of gamma linolenate and eicosapentaenoate, but significantly reduced by docosahexaenoate. These effects on cell numbers were rapid in onset. Following only 2 days exposure to low concentrations of the fatty acids, cell numbers in the breast tumour cell line, MCF-7, were significantly reduced relative to controls. In contrast, the colon cell line, WiDR, was largely unaffected at this time, and in some cases, cell numbers were significantly increased. In the normal fibroblast cell line, cell numbers were significantly reduced by docosahexaenoate at concentrations greater than or equal to 20 mu g/ml. Following only 2 days exposure to PUFA, cell death in the breast cell cultures was maximally increased above controls by 20 mu g/ml of docosahexaenoate, whereas cell proliferation was unaffected at this concentration. In contrast, under these circumstances, cell proliferation in the colon cell cultures was significantly increased by this PUFA while there were only small increases in cell death. Our observations have highlighted the differential responses of human tumour cell lines to PUFAs and documented the stimulation of a colon cell line by certain PUFAs.     

The necessity of a second prostate biopsy cannot be predicted by PSA or PSA derivatives (density or free:total ratio) in men with prior negative prostatic biopsies

Serum prostate specific antigen, prostate specific antigen density and free:total prostate specific antigen are known to be useful for determining the risk of prostate cancer in patients undergoing prostate cancer screening. The patient with a positive biopsy presents no future prostate specific antigen dilemma. Those with negative biopsies often go on to numerous repeat biopsies. Our goal was to establish criteria that could be used to identify patients who will require repeat prostate biopsies (possibly false negative initial biopsy), while not exposing the low risk population (probable true negative initial biopsy) to additional invasive procedures. Between March 1991 and March 1998, 148 patients who had a biopsy for an elevated prostate specific antigen value (4.1-10.0) or an altered digital rectal examination, had no cancer found in the specimen. From these, 51 (34.4%) had repeated biopsies, while the others persisted on close follow-up. We examined their serum prostate specific antigen, prostate specific antigen density and free:total prostate specific antigen value, as well as their age and histology results of the initial and repeat biopsy, to determine if any predictor of the need for a repeat biopsy could be identified. Eight (15.7%) from 51 men who had repeat biopsy had prostate cancer detected. Forty three (84.3%) patients persisted with a negative biopsy, despite filling the criteria for re-biopsy. Multivariate analysis failed to identify any significant predictors of prostate cancer in the repeat biopsy group. Despite initial success, the prostate specific antigen derivatives and free:total prostate specific antigen have not safely limited the number of biopsies performed for an abnormal prostate specific antigen (4.1-10.0). Neither prostate specific antigen density nor free:total prostate specific antigen predicted the need for repeat biopsy in this specific group. The results of this ongoing study demonstrate that to date, prostate specific antigen and prostate specific antigen derivatives can not be utilized to determine which patients will be at high risk for requiring repeat prostate biopsy. All patients must be closely monitored for evidence of a change in status from benign to malignant disease, and new markers for this purpose are urgently needed.     

The use of proteases as prognostic markers for the healing of venous leg ulcers

Abnormally high levels of some proteases are associated with pathological changes in the wound bed of venous leg ulcers. This study involved two experiments which measured proteases in wound fluid harvested from leg ulcers in order to predict healing. In the first experiment, neutrophil elastase, a protease, was harvested from wound fluid extracted from the bandages of seven patients with leg ulcers. This was undertaken once a week over a period of up to six weeks. The amount of elastase recovered from the bandages showed wide variation between patients and there was no consistent correlation between the activity of elastase and healing of the ulcers, as determined nine months after sampling for the enzyme. The second experiment determined the stability of neutrophil elastase that was added to bandages for one week. The stability was found to vary from approximately 50% to 100%, depending on the type of bandage used. In addition to the possibility of using protease measurements to predict healing, the procedure was found to be simple, non-invasive and relatively inexpensive, and could be performed routinely in the clinic.     

What do patients want and do we want to know? A review of patients' requests of psychiatric services

OBJECTIVE: A systematic review was conducted of the literature concerning patients' requests of psychiatric care in order to identify the types of requests patients make, psychiatrists' perceptions of their patients' requests, and the relationship between requests and the outcome of care. METHOD: A total of 28 published original articles which fulfilled specific inclusion criteria were reviewed. RESULTS: The studies showed that there are certain core requests that patients make irrespective of the type of service attended. Patients mainly request psychological approaches, and the most common requests are for 'clarification', 'psychological expertise' and 'psychodynamic insight'. There is evidence that patients normally feel inhibited about making requests, and that psychiatrists often fail to identify what their patients want. CONCLUSION: The majority of patients attending psychiatric services have requests which they will express when encouraged to do so, but little is known about the relationship between patients' requests and the outcome of care. Recommendations are made for future research.     

Vagal control of heart rate is modulated by extracellular potassium

Heart rate (HR) recovery from heavy exercise is associated with a shift in cardiac sympatho-vagal balance and a transient hypokalaemia. Since changes in extracellular potassium ([K+]0) affect membrane currents in the sino-atrial node, in particular the acetylcholine-activated potassium current (I(K,ACh)), the hyperpolarization-activated current (I(f)) and the L-type calcium current (I(Ca,L)), we investigated whether mimicking [K+]0 concentrations seen during and immediately after exercise could directly modulate the HR response to vagal nerve stimulation (VNS) in the isolated guinea-pig atria preparation pre-stimulated with noradrenaline (NA, 1 microM). Lowering [K+]0 from 4 to 3 mM significantly enhanced the HR response to VNS (5 Hz, 5 V, 30 s, deltaHR 84.5 +/- 14.1 bpm and 119.3 +/- 18.2 bpm, respectively). Increasing [K+]0 to 8 or 10 mM significantly decreased the drop in HR with VNS in comparison to the response to 3 mM K+ Tyrode (deltaHR 56.4 +/- 9.1 bpm and 52.1 +/- 8.7 bpm, respectively). These results could be simulated using the OXSOFT heart sino-atrial node computer model by activating I(K,ACh) during changes in [K+]0. However, changing [K+]0 in the model had no significant effect on the decrease in beating frequency brought about by decreasing I(f) or I(Ca,L). We conclude that the magnitude of the decrease in HR with VNS is enhanced in low [K +]0 and reduced in high [K+]0. The increased efficacy of cardiac vagal activation in low [K+]0 might therefore facilitate the drop in HR after heavy exercise where there is a transient hypokalaemia. Modelling suggests this result may be explained by the effects of changes in [K+]0 on the current-voltage relationship for I(K,ACh).     

The comparative validity of eleven alcoholism typologies

OBJECTIVE: This study directly compared the clinical validity of 11 empirically defined alcoholism typologies to determine whether some typologies are clinically more valid than others. METHOD: A sample of 360 hospitalized alcoholic men were extensively evaluated at entry into the study and again 1 year later. Twenty-three measures of clinical validity were employed; 15 were postdictive and 8 were predictive. Postdictive retrospective measures obtained at entry into the study included family history, age of onset and lifetime course characteristics associated with alcoholism severity, general psychopathology and psychosocial functioning. Predictive outcome measures drawn from information obtained during the 1-year follow-up included: abstinence, alcoholism severity and clinician ratings of outcome. The measures were subjected to various statistical analyses, including factor analysis. RESULTS: We found that all of the alcoholism typologies met at least 7 of the 23 a priori measures of clinical validity. The correlations between these conceptually and methodologically disparate typologies were often striking. Exploratory factor analysis, which explained 35% of the variance, suggested three possible underlying dimensions to account for the overlap among typologies: (1) age and its correlates, including age-of-alcoholism onset; (2) "pure" alcoholism versus psychiatrically heterogeneous alcoholism that encompassed antisocial personality disorder; and (3) current severity of psychiatric distress, impairment and dysfunction. CONCLUSIONS: No single method of subtyping alcoholics clearly emerged as superior. All demonstrated some degree of predictive and postdictive clinical validity. Most methods of subtyping correlated positively with each other at moderate, but typically significant, levels.     

"Mixed inhibitor-prodrug" as a new approach toward systemically active inhibitors of enkephalin-degrading enzymes.

In order to evaluate the possible advantages of potentiating the effects of the endogenous enkephalins, to obtain analgesia without the serious drawbacks of morphine, it was essential to design systemically active compounds which inhibit the two metabolizing enzymes, aminopeptidase N (APN) and neutral endopeptidase 24.11 (NEP). A new concept combining the idea of "prodrug" and "mixed inhibitor" was therefore developed. Given the high efficiency of beta-mercaptoalkylamines as APN inhibitors and of N-(mercaptoacyl) amino acids as NEP inhibitors, compounds associating these molecules through disulfide or thioester bonds, which are known to increase lipophilicity and to favor passage across the blood-brain barrier, have been synthesized. An HPLC study indicated that the disulfide bridge was resistant to serum enzymes but was cleaved by brain membrane homogenates, suggesting that the active inhibitors were released in the central nervous system. The validity of the approach was verified by the efficient antinociceptive responses obtained in the hot plate test in mice after iv administration of disulfide-containing inhibitors (ED50s of from 4 to 26 mg/kg on the jump latency time). The analgesic potencies of the "mixed inhibitor-prodrug" RB 101 [H2NCH(CH2CH2SCH3)CH2SSCH2CH(CH2Ph)CONHCH( CH2Ph)COOCH2Ph] after iv administration were three times greater than those of a similar combined dose of its two constitutive moieties. The separation of the two diastereoisomers constituting RB 101 showed that the analgesia has a stereochemical dependence, the (S,S,S)-isomer being more active than the (S,R,S)-isomer. Furthermore, in the tail flick test in the rat, RB 101 gave 38% analgesia at a dose of 80 mg/kg. Due to its high efficiency and its longer pharmacological effect, RB 101 was selected for a complete study of its analgesic properties.