Mobile ionophores are a novel class of P-glycoprotein inhibitors. The effects of ionophores on 4'-O-tetrahydropyranyl-adriamycin incorporation in K562 drug-resistant cells

The decrease of the intracellular concentration of drug in resistant cells compared to sensitive cells is, in most cases, correlated with the presence, in the membrane of resistant cells, of a 170-kDa P-glycoprotein responsible for an active efflux of the drug. In an attempt to identify mechanism(s) by which multidrug resistance can be circumvented, we have examined the cellular accumulation of 4'-O-tetrahydropyranyl-adriamycin, alone and in conjunction with various ionophores on the one hand and with cyclosporin A on the other hand. The present study was performed using a spectrofluorometric method with which it is possible to follow continuously the uptake and release of fluorescent molecules by living cells, as the incubation of the cells with the drug proceeds. Erythroleukemia K562 cell lines were used. Using experimental conditions in which these ionophores were unable to modify either the intracellular pH, or the transmembrane potential, or to induce an intracellular ATP depletion, we have shown that mobile ionophores as well as cyclosporin inhibit the P-glycoprotein-mediated efflux of 4'-O-tetrahydropyranyl-adriamycin in K562 resistant cells, whereas gramicidin, a channel-forming ionophore, does not. The concentration that must be used to inhibit 50% of the efflux was 0.7 microM for valinomycin, 0.4 microM for nonactin, 0.2 microM for nigericin, 1.1 microM for monensin, 0.4 microM for lasalocid, 1.2 microM for calcimycin and 0.4 microM for cyclosporin. Due to the high toxicity of the ionophores, the observation that they increased 4'-O-tetrahydropyranyl-adriamycin accumulation in the multidrug-resistant cells is not correlated with an effect of these compounds on drug resistance. However, the correlation exists in the case of cyclosporin. From our data showing that lipophilic neutral complexes, formed between carboxylic ionophores and metal ions, are both able to inhibit the P-glycoprotein-mediated efflux of anthracycline we can infer that the lipophilicity but not the cationic charge is an important physical property.

Correlation between the short-term measurements of drug accumulation in living cells and the long-term growth inhibition

The basic distinguishing feature of all cells expressing functional P-glycoprotein-multidrug resistance (P-gp-MDR) is a decrease of steady state drug levels as compared to drug-sensitive controls. Recently it has been pointed out that there appears to be a discrepancy between the amount of drug accumulated at steady state by drug-sensitive and highly resistant cells and their degree of resistance. These observations could suggest two things: (1) that factors other than drug accumulation may be important in MDR, (2) that they reflect a discrepancy between the short-term measurements of drug accumulation at 60 min versus long-term (72 hr) growth inhibition. Due to the different experimental conditions and the different type of cells used it is very difficult to compare the literature data. For this reason we have investigated the effect of 12 compounds in overcoming resistance in relation to drug accumulation. We have used a spectrofluorometric method which allows the determination of the nuclear drug accumulation directly on living cells. Our data clearly establish that, at least for the compounds used in that study, there is a very good correlation between their ability to increase drug accumulation, measured at short-term, and their ability to reverse MDR accumulation, measured at short-term, and their ability to reverse MDR, but no correlation with their ability to inhibit protein kinase C activity. In addition, their efficiency to reverse MDR correlates with their pKa values, the efficiency being the highest when the pKa is the lowest.

[Primary intrahepatic lithiasis: report of a case and review of the literature]

Primary intrahepatic lithiasis is an entity defined by intrahepatic stones exclusively located in the IH ducts above the emergence of the common bile duct. The disease is classified in two types: Eastern type (stones formed primarily in intrahepatic ducts; frequent in Japan) and Western type (stones formed in the extrahepatic bile system, usually in gallbladder, which migrate up to the intra-hepatic ducts). The mechanisms of lithogenesis in the entity are as yet not fully understood; multiple factors seem to operate synergistically: anatomical changes of the intrahepatic ducts, metabolic disorders, infections, idiopathic alteration. All these factors may facilitate biliary stasis leading ultimately to stone formation. We report on a case of and review the literature on primary intrahepatic lithiasis, which is a rare occurrence in the West and a disease of difficult surgical approach and high mortality.

Non-competitive inhibition of P-glycoprotein-associated efflux of THP-adriamycin by verapamil in living K562 leukemia cells

The decrease of the intracellular concentration of drug in resistant cells as compared to sensitive cells is, in most of cases, correlated with the presence, in the membrane of resistant cells, of a 170-kDa P-glycoprotein (P-gp) responsible for an active efflux of the drug. The fluorescence emission spectra from anthracycline-treated cells suspended in buffer have been used to follow the P-gp-associated efflux of these drugs in the absence or presence of verapamil. In the present study, 4'-o-tetrahydro-pyranyladriamycin (THP-adriamycin) was used. Two different methods were used to determine the kinetics of active efflux of THP-adriamycin: (1) at the steady-state, (2) directly, after the addition of glucose to cells first incubated with THP-adriamycin in the presence of N3- and in the absence of glucose. Kinetic analysis indicates: (1) a saturation of the active efflux when the cytosolic free drug concentration increased (the Michaelis constant Km = 0.5 +/- 0.3 microM) and (2) that the inhibitory effect of verapamil on P-gp-associated efflux of THP-adriamycin in living cells is non-competitive.

[Activities at the polyvalent intensive care unit of the Santo António dos Capuchos Hospital]

The authors present an audit to a multidisciplinary Intensive Care Unit of a tertiary Hospital (HSAC) over its first year (1/07/1991-30/06/1992). The total study population numbered 282 patients, 52.5% admitted from the emergency room. The mean age was 57.91 +/- 18.16 years. Cardiovascular failure (39%) and respiratory failure (35%) were the main diagnostic categories for admission; 50.7% of the patients needed mechanical ventilation, 44% echocardiogram, 13.5% bronchoscopy and 10.3% hemodynamic evaluation with Swan-Ganz catheter. These are patients with high mean values of severity scoring systems, ICU mortality (27%) and Hospital mortality (37.6%). APACHE II, SAPS I and TISS on day one of admission and maximum value over a 24 hour period of two multiple organ failure systems-MOF and OSF were validated in this population and were good outcome predictors.

Late outcome of unsupported annuloplasty for rheumatic mitral regurgitation

OBJECTIVES

The aim of this study was to evaluate medium- and long-term (range 4 months to 17 years) clinical results in a series of patients treated surgically by unsupported mitral annuloplasty.

BACKGROUND

Mitral valve regurgitation has usually been treated by valve replacement or ring annuloplasty. A few series have reported plastic repair procedures without annular support or remodeling. Furthermore, in rheumatic lesions the results have been inferior to those in degenerative mitral insufficiency, and the majority of previous reports have provided information on short- or medium-term follow-up.

METHODS

One hundred fifty-four patients were operated on (55 male [36%] and 99 female [64%]). The mean age +/- SD was 36 +/- 16 years (range 5 to 73). Associated lesions comprised 47 aortic and 21 tricuspid valve lesions and 2 atrial septal defects. Patients with concomitant mitral stenosis were not included. Preoperative functional class was I or II in 19% and III or IV in 81%. The cardiothoracic ratio was 0.61 +/- 0.10. All patients underwent an unsupported mitral annuloplasty procedure in which the mural portion of the annulus was reduced by applying two buttressed mattress sutures at the commissures without compromising the width of the septal leaflet. When necessary, additional chordal procedures were performed. No patients received ring or posterior annular support.

RESULTS

The early mortality rate was 1.9% (three patients; one of the three died of myocardial failure and two of pulmonary thromboembolism). The late mortality rate was 5.8% (nine patients; three of the nine died of myocardial failure, one each of septicemia, pulmonary thromboembolism and sudden arrhythmic death and three of unknown causes). Twenty-eight patients (18.2%) were reoperated on because of mitral valve dysfunction and 2 (1.3%) because of prosthetic aortic valve dysfunction. A residual late systolic murmur was present in 48% of patients. Late complications were systemic thromboembolism in 5.8% (one third with an aortic valve prosthesis), infective endocarditis in 1.3% and pulmonary thromboembolism in 0.6%. Postoperative functional class was I or II in 84% and III or IV in 16%. Cardiothoracic ratio was 0.58 +/- 0.10. Actuarial probability of late survival was 79.5 +/- 5.3% at 10 years and 71.0 +/- 7.4% at 14 years. Event-free survival was 67.9 +/- 8.9% at 10 years and 56.1 +/- 11.7% at 14 years.

CONCLUSIONS

Rheumatic mitral regurgitation can be effectively treated by annuloplasty without prosthetic annular support, with late results comparable to those obtained with more complicated procedures. This observation is particularly important for treatment of children and young adult patients.

Increased risk of meningitis and bacteremia due to Listeria monocytogenes in patients with human immunodeficiency virus infection

The incidence, demographics, and clinical outcome of infections due to Listeria monocytogenes in individuals infected with the human immunodeficiency virus (HIV) were evaluated by prospective population-based surveillance. During a 2-year study period, 37 cases of invasive listeriosis occurred in metropolitan Atlanta (annual incidence, 0.8 case per 100,000 population). Seven of these cases occurred in known HIV-infected individuals (19% of all cases); five had an AIDS-defining illness, and the other two had CD4 lymphocyte cell counts of < 200/microL. The estimated incidence of listeriosis among HIV-infected patients in metropolitan Atlanta was 52 cases per 100,000 patients per year, and among patients with AIDS it was 115 cases per 100,000 patients per year, rates 65-145 times higher than those among the general population. HIV-associated cases occurred in adults who were 29-62 years of age and in postnatal infants who were 2 and 6 months of age. Mortality among the HIV-infected group was 29%. L. monocytogenes serotypes 1/2a, 1/2b, and 4b were isolated from the HIV-infected patients. L. monocytogenes is an important opportunistic pathogen in HIV-infected patients.

(+)-Anatoxin-a is a potent agonist at neuronal nicotinic acetylcholine receptors

The effects of the nicotinic agonist (+)-anatoxin-a have been examined in four different preparations, representing at least two classes of neuronal nicotinic receptors. (+)-Anatoxin-a was most potent (EC50 = 48 nM) in stimulating 86Rb+ influx into M10 cells, which express the nicotinic receptor subtype comprising alpha 4 and beta 2 subunits. A presynaptic nicotinic receptor mediating acetylcholine release from hippocampal synaptosomes was similarly sensitive to (+)-anatoxin-a (EC50 = 140 nM). alpha-Bungarotoxin-sensitive neuronal nicotinic receptors, studied using patch-clamp recording techniques, required slightly higher concentrations of this alkaloid for activation: Nicotinic currents in hippocampal neurons were activated by (+)-anatoxin-a with an EC50 of 3.9 microM, whereas alpha 7 homooligomers reconstituted in Xenopus oocytes yielded an EC50 value of 0.58 microM for (+)-anatoxin-a. In these diverse preparations, (+)-anatoxin-a was between three and 50 times more potent than (-)-nicotine and approximately 20 times more potent than acetylcholine, making it the most efficacious nicotinic agonist thus far described.

Antihypertensive efficacy, safety, and tolerability of isradipine in hypertensive patients with diabetes

The aim of this study was to investigate the efficacy, tolerability, and safety of isradipine in hypertensive diabetic patients. Twenty-eight patients (14 men and 14 women), of whom 15 had type II (non-insulin-dependent) and 13 had type I (insulin-dependent) diabetes mellitus, received isradipine for 6 months. A significant reduction was observed in both systolic and diastolic blood pressures (P < .00005). There were no significant differences between the type I and type II diabetes patients; metabolic control remained stable. Moderate or slight headaches were reported by four patients. In conclusion, the overall efficacy of isradipine and its tolerability were found to be very good.

[The use of a rate-responsive pacemaker after heart transplantation]

PURPOSE

The indications and the results of pacemaker implant following orthotopic cardiac transplantation.

METHODS

Four patients implanted a cardiac pacemaker (PM) in the early post-operative period (PO) of orthotopic cardiac transplantation (from 10th to 16th PO day). The patients were 33 to 55 year-old and the indications to PM were supraventricular arrhythmia (atrial fibrillation or flutter) associated with atrioventricular block in three, and complete atrioventricular block in one patient. Previous to PM implant, patients were submitted to endomyocardial biopsy, which was normal in two patients, evidenced mild rejection in one and moderate rejection in the remaining. A ventricular rate responsive pacemaker was implanted in all patients, with sensors responsive to muscular activity in one patient, and to minute ventilation in three.

RESULTS

One patient died in the 20th PO due to acute allograft rejection not controlled by immunosuppressive drugs. Three other patients had satisfactory evolution and the pacemakers were programmed during exercise testing, previous to hospital discharge. Recent evaluation revealed that these patients are in good clinical condition at the 6th, 14th and 24th PO months. Adequate pacemaker function was insured by exercise testing and ambulatory electrocardiographic recording.

CONCLUSION

A ventricular rate responsive pacemaker represented a satisfactory mode of pacing, in patients with severe bradycardia, following heart transplantation.

[Hospital risk factors in subclavian-pulmonary anastomosis with polytetrafluoroethylene graft]

PURPOSE

Identification of risk factors for mortality in subclavian-pulmonary anastomosis using polytetrafluorethylene (PTFE).

PATIENT AND METHODS

Immediate surgical results (30 days) were analyzed in 180 cyanotic patients consecutively operated on from september 1979 to march 1989.

RESULTS

The hospital mortality was 12.7% (23 patients) and age at surgery, low weight (less than 3 kg) and preoperative diagnosis were considered risk factors for mortality. Pulmonary artery diameter at echocardiography, date of surgery and diameter of the conduits were associated with increased risk, but this association lacked statistical significance. Sex and previous palliative surgery have not increased hospital mortality.

CONCLUSION

We believe that identification of risk factors to PTFE conduit implant plays an important role in the preoperative management of those patients in order to obtain better results in this life saving procedure.

[Chronic hypoparathyroidism: review of 5 clinical cases]

In 5 patients with a long clinical evolution of tetany and/or convulsions and with documented hypocalcaemia and hyperphosphatemia, low or inappropriate values of parathormone were detected. Only two of the patients had a history of subtotal thyroidectomy and all presented with basal ganglia calcification, bilateral subcapsular cataracts and prolonged QTc interval in the ECG. After one month of oral therapy with calcium and calcitriol, the values of calcaemia and phosphatemia were in a near-normal range with the exception of a patient in which that normalization was much slower and only occurred after correction of magnesaemia. In this last patient statistical correlation between QTc interval in the ECG and the calcaemia was statistically significant (P less than 0.001). We conclude that the QTc interval can be a useful and accessible index in acute situations of symptomatic hypocalcaemia.

[Assessment of the first myocardial infarctions with lead ECG --implications in the study of hospital mortality and its reduction using thrombolytic drugs]

STUDY OBJECTIVE

Correlation between mortality reduction of first Myocardial Infarction (MI) by thrombolytic therapy and MI size evaluated with the classical Electrocardiogram (ECG).

DESIGN

A retrospective sequential study.

SETTING

Coronary Unit patients.

PATIENTS

Sequential sample of 132 patients with first MI obeying all the following criteria: 1) no previous MI; 2) age less than or equal to 70 years; 3) clinical evolution less than 12 hours; 4) no Left Bundle Branch Block in the CCU first ECG; 5) ischemic ST elevation in greater than or equal to 1 initial ECG leads. Patients were divided into Group A, with less than or equal to 3 initial ECG leads with ischemic ST elevation (n = 80), and Group B, with greater than or equal to 4 initial ECG leads with ischemic ST elevation (n = 52). Only 34 patients (25.7%) did thrombolytic therapy with IV Streptokinase (SK); 15 from Group A and 19 from Group B.

MEASUREMENTS AND MAIN RESULTS

17 patients died in MI acute phase (12.8%); 4 in Group A (5%) and 13 in Group B (24.9%). Inhospital mortality was statistically worst in Group B than in Group A (24.9% vs 5% with p less than 0.01). Creatin kinase (CK) maximal values (A = 911.5 UI; B = 1444.6 UI with p less than 0.01) and initial Heart Rate (A = 75.7; B = 86.7 with p less than 0.001) were also statistically greatest in Group B. Inhospital mortality was smaller in patients treated with SK (8.8% vs 14.3%), as in Group B (10.5% vs. 33.3%), both without statistical significance.

CONCLUSIONS

Inhospital mortality and thrombolytic therapy benefit were so bigger as MI size evaluated by the number of initial ECG leads with ischemic ST elevation, by initial HR and maximal values of CK. Classical ECG can be useful by identifying patients with first MI that can more benefit with thrombolytic therapy (greater than or equal to 4 leads with ischemic ST elevation).

[Influence of body fat topography on glucose homeostasis and serum lipids]

Predominant fat distribution in the upper body segment evaluated by waist to hip circunference ratio (WHR) has been associated with diabetes mellitus and cardiovascular morbidity excess. To investigate metabolic alterations underlying this risk excess, we selected 2 groups of 10 obese women without history of hypertension, menstrual irregularities or oral contraceptives, matched according to age (mean +/- SD): 30.5 +/- 5.3 vs 30.6 +/- 5.8 years and BMI 35.5 +/- 6.5 vs 35.7 +/- 6.7 Kg/m2. Each matched pair had a difference in WHR superior to 0.15 (0.83 +/- 0.04 vs 1.02 +/- 0.05). Insulin and C peptide were determined during an oral glucose tolerance test (75 g). At 30, 60, 90 and 120 minutes differences were significant for glycaemia, insulinaemia and C peptide. Fasting triglycerides were 103 +/- 48 in the lower WHR group vs 164 +/- 84 mg/dl (p less than 0.05); total cholesterol 186.5 +/- 31 vs 215.2 +/- 29.4 mg/dl (p less than 0.05); LDL cholesterol/HDL cholesterol 2.46 +/- 0.89 vs 3.18 +/- 0.96 (p less than 0.05). No significant differences were found in androgenic activity. We conclude that preferential fat distribution in the upper segment is, by itself, an aggravating factor of metabolic alterations associated with obesity, particularly dyslipidaemia and hyperinsulinaemia.

[The diabetic foot]

A review of the physiopathology of foot problems in diabetics is presented and the need for all the members of the health care team to take part in educating the diabetic in appropriated foot care is stressed. A quick evaluation of three components (vascular, neuropathic and infectious) is essential. Primary and secondary prevention with proper evaluation of predisposing and precipitating factors are stressed as fundamental to reduce the number of amputations and improve quality of life.

Self-inflicted burns

Suicide by self-inflicted burns is uncommon in Western cultures. The majority of patients who attempt suicide in this manner have preexisting psychiatric illness, including a history of prior suicide attempts. A history of previous self-inflicted burn is rare, however, as are further suicide attempts in survivors. In this series of 33 patients, a cultural trend can be identified, with an increased incidence among Latin women.

On using a self-tuning controller for blood pressure regulation during surgery in man

The generalized minimum-variance self-tuning controller of Clarke and Gawthrop has been used to adjust the flow rate of a modified Vickers Treonic IP4 syringe pump delivering phenylephrine to 20 patients undergoing lower abdominal surgery during epidural analgesia. This proved to be a very effective method of restoring and maintaining normal arterial pressure. The method has also been used to produce controlled hypotension in 18 patients undergoing plastic or neurosurgical procedures via sodium nitroprusside infusions. Valuable insight into patient responses to surgical stimuli, blood loss, fluid loads, opioids, relaxants and other agents was provided.

Auscultatory measurement of arterial pressure during anaesthesia: a reassessment of Korotkoff sounds

The accuracy of the indirect auscultatory method, using Korotkoff sounds for determination of arterial pressures, was investigated by comparison with direct intra-arterial measurements. Eight hundred and sixty-three comparisons were made in 25 patients aged between 27 and 75 years over blood pressures ranging from 59 to 235 mmHg for systolic and 28 to 145 mmHg for diastolic. The regression equation for all systolic pressure measurements was y = 13.9 + 0.81x, and for all diastolic pressure measurements was y = 21.4 + 0.71x. Although there was a significant (P less than 0.001) correlation coefficient between direct and indirect measurements for both systolic (r = 0.93) and diastolic pressures (r = 0.79), the 95% confidence limits (+/- 22 mmHg for systolic and +/- 19 mmHg for diastolic) were very wide, reflecting the influences of observer variation and other sources of error.

Angiography in cystadenoma and cystadenocarcinoma of the pancreas

The angiographic findings 9 surgically proved cases of primary cystic neoplasms of the pancreas are reported. Angiography demonstrates the extent and origin of the tumour and permits in many cases a differentiation between benign and malignant lesions.

Five years' experience with intrauterine transfusion

Five years' experience with intrauterine transfusion involving 94 transfusions on 50 fetuses forms the basis of the paper. Twenty-three fetuses survived, which represents an overall salvage of 46%. Of 22 fetuses who received intrauterine transfusions before 28 weeks' gestation, seven (31.9%) survived, which justifies the attempt. Of 28 fetuses who received intrauterine transfusions after 28 weeks' gestation, 16 (57.1%) survived, which compares favourably with other series. A comparison of two different procedural techniques shows no statistically significant difference in ultimate results. Indications for amniocentesis are outlined and intrauterine transfusion was advised if the optical density difference fell in Liley's zone III (or a very high zone II) and rose at a rate which anticipated a zone III reading prior to 32 weeks' gestation. A pediatric assessment and therapeutic management of the 33 live births are presented. Twenty-eight babies received exchange transfusions. Five were excluded for reasons outlined in the text. Ten of the live-born died neonatally. The 23 survivors continue to thrive mentally and physically and follow-up continues.