Polarographic Assay of Submicrogram Quantities of Cis-Dichlorodiamineplatinum (II) in Biological Samples

Differential pulse Polarographic assay of the antineoplastic agent cis-dichlorodiamineplatinum II and its analogues was performed after acid oxidative hydrolysis (HCIO4, HNO3, HCI) of biological samples (plasma, tissue homogenates, urine) and reaction with ethylenediamine. Platinum levels and kinetics were determined in blood and urine of patients with non-oat-cell lung carcinoma. Detection limit of the polarographic assay was 0.5 ng platinum; analytical error was ± 3%. Levels of free cis-dichlorodiamineplatinum (II) in plasma fell in samples stored at –20 °C; the half-life of free drug was 38 h.

Renin-angiotensin system at the crossroad of hypertension and hypercholesterolemia

AIM

The aim of this study is to discuss the reliable scientific evidence of an interactive link between hypertension and hypercholesterolemia considering the metabolic pathways and the pathogenetic mechanisms connecting the two risk factors.

DATA SYNTHESIS

Hypertension and hypercholesterolemia are highly prevalent in the general population and their coexistence in the same subjects additively increases the risk of cardiovascular disease. Probably, hypercholesterolemia is also a risk factor for the development of hypertension. On the other side, it is also possible that lipid-lowering treatment could improve blood pressure control. Although the mechanisms of interaction between these two risk factors have not been completely elucidated thus far, there is rapidly growing evidence that the involvement of the renin-angiotensin system (RAS) can be considered as the common link between hypertension and hypercholesterolemia. In particular, hypercholesterolemia seems to promote the upregulation of type 1 angiotensin II (AT1) receptor genes because of an increase in the stability of mRNA followed by structural overexpression of vascular AT1 receptors for angiotensin II. The treatment of both risk factors greatly improves individual risk profile, especially when statins and RAS blockers are used together.

CONCLUSIONS

Hypertension and hypercholesterolemia are highly coprevalent and strongly related from a pathophysiological point of view. The RAS could be the main mediator of this link.

Prognostic significance of serum uric acid in outpatients with chronic heart failure is complex and related to body mass index: data from the IN-CHF Registry

BACKGROUND AND AIMS

In the field of cardiovascular diseases, elevated levels of serum uric acid (UA) reflect a marked activation of the xanthine oxidase pathway with increase in free radicals production; it is often associated with an inflammatory state, oxygen consumption and endothelial dysfunction. All these associations have been also confirmed in heart failure (HF) but the pathophysiological role of UA in this setting is not well understood. The aim of this study was to evaluate the prognostic role of UA in outpatients enrolled in the Italian Registry of Congestive Heart Failure (IN-CHF).

METHODS AND RESULTS

All patients met the European Society of Cardiology (ESC) criteria for diagnosis of HF. We considered patients with complete clinical data and UA level available at the baseline and at 1-year follow-up. The study population was composed of 877 patients aged 63 ± 12 years. One-year mortality was 10.8% and dead patients had a higher level of UA than survivors (7.1 mg dl⁻¹ vs 6.6 mg dl⁻¹, p < 0.0207). In multivariable full model of analysis, UA did not result in an independent predictor of death in overall population, but only in patients with low body mass index (BMI) (≤22 kg m⁻²) (hazard ratio (HR): 2.38, 95% confidence interval (CI) 1.36-4.18). In this subgroup, a statistically significant gradual relationship between UA and survival was detected starting from values higher than 8 mg dl⁻¹.

CONCLUSION

Elevated level of UA is not an independent predictor of mortality in chronic HF, but it markedly worsens outcome if associated with low level of BMI. This association is likely an indicator of chronic inflammatory and catabolic state.

[Is viscoelastic the corneal tissue?]

PURPOSE

To compare the known viscoelastic properties of soft tissues with singular published observations on the behaviour of corneal tissue.

MATERIALS AND METHODS

The behaviour of the maxwellian element, typical viscoelastic biomechanical model, is compared with that of various previously studied soft tissues of animals. The same comparison can be made between stress-strain curves of riboflavin and UVA treated and untreated strips of human and porcine corneal tissue, stretched at constant velocity, from the literature.

RESULTS

The asymptotic stress-strain curves of the various soft tissues previously examined could be faithfully simulated by the Maxwell viscoelastic element. The exponential stress-strain curves of samples of corneal tissue were clearly different.

CONCLUSIONS

The observed divergence demonstrates incompatibility between the alleged behaviour of corneal tissue and the viscoelastic properties attributed to it. Thus there are two possibilities: either corneal tissue is viscoelastic and the experiment showing exponential behaviour suffers from some technical problem, or the data is correct and corneal tissue is not viscoelastic. In either case further research is necessary for correct interpretation of the mechanism of cross-linking and for consequent therapeutic choices.

Chemotherapy-induced myelosuppression by vinorelbine: a comparison between different dose schedules by simulation

A pharmacokinetic-pharmacodynamic (PK-PD) model was developed to simulate the plasma profile and the toxicity of vinorelbine after multiple oral dose treatment to humans. The PK drug profile was described by a three-compartment open model linked to a PD model aimed to describe the drug toxicity on the circulating neutrophils. Different dose schedules were simulated holding the total administered dose constant (100 mg p.o. during two weeks): 7.7 mg daily (13 doses), 20 mg every 3 days (5 doses) and 33.3 mg every 6 days (3 doses). The lowest values of the circulating neutrophils were observed after 18 days from the start of the treatment and at nadir the fraction of the circulating neutrophils were 0.733, 0.703 and 0.681 after the three doses in decreasing order. These differences were not clinically significant, however the drug bioavailability, which was fixed to 0.35 in the simulation, might be highly variable among subjects contributing to a large extent to the observed variability in drug toxicity.

Prognostic value of differential expression of Laminin-5 gamma2 in oral squamous cell carcinomas: correlation with survival

In oral squamous cell carcinomas of the head and neck, Laminin-5 gamma2 has been associated with tissue invasion, lymph node metastasis and histopathological grading. In the present study, we compared the expression of the subunit gamma2 of Laminin-5 under normal, dysplastic and invading epithelia in 65 biopsies previously diagnosed for oral squamous cell carcinoma. The number of gamma2-positive cells were analyzed in relation to patients' survival, tumor grading, size of the lesion, TNM stage, histopathological pattern of invasion and inflammatory reaction. Biopsies of oral squamous cell carcinomas were deparaffinised, processed for antigen unmasking procedures and stained with antibody anti-Laminin-5 gamma2. By light microscopy, 4 optical fields of x200 were selected in three different areas including normal, dysplastic and invading epithelia. Positive cells were counted and divided into three categories, which included <20 cells, between 21 and 50 cells and >50 stained cells. Patient survival was analyzed by Kaplan-Mayer curves. gamma2-positive cells were found in the basal layer of dysplastic epithelium, within inflammatory infiltrate, at the margins of differentiated invading islands and at the forefront of undifferentiated invading nests. Observations showed that an increased number of gamma2-positive cells correlated significantly with a shorter life expectancy under invading epithelia (log-rank test p<0.05), not when a count was performed under normal or dysplastic epithelia of the same patient. The number of gamma2-positive cells also correlated with the histopathological pattern of invasion. Our results show that gamma2 may be a reliable prognostic tool for oral squamous cell carcinomas.

Classical and molecular analyses to characterize commercial dry yeasts used in wine fermentations

AIMS

The aim of the work was to apply PCR-temperature gradient gel electrophoresis (PCR-TGGE) and restriction enzyme analysis (RE) assays to identify commercially available starters of Saccharomyces cerevisiae sensu stricto complex.

METHODS AND RESULTS

To characterize an analysed pool of 62 active dry yeasts of different brands used in wine fermentation practices, classical microbiological tests were also performed as well as evaluation of contamination with lactic acid bacteria and non-Saccharomyces yeasts. PCR-TGGE and RE were used in order to provide fast and reliable methods to identify and differentiate enological yeasts. Proposed molecular methods enabled to identify particular strains within 36 h after colony isolation and directly from dry yeast suspension.

CONCLUSIONS

The methods are highly recommended to obtain reliable results on yeast strain differentiation in a significantly shorter time if compared to classical fermentation tests.

SIGNIFICANCE AND IMPACT OF THE STUDY

The obtaining of yeast strain differentiation in a short time and without plating is a good tool for a rapid discrimination among enological strains used as starters in enological practices.

Pharmacokinetics of mitomycin C after resection of peritoneal carcinomatosis and intraperitoneal chemohyperthermic perfusion

Over the last few years surgery on patients with abdominal malignancies has become more aggressive but the majority of patients present locoregional recurrence as peritoneal dissemination. Cytoreductive surgery followed by intraperitoneal chemohyperthermic perfusion (ICHP) has been described for treatment and prevention of locoregional cancer spread from various origins. This paper reports our study of the pharmacokinetics of mitomycin C (MMC) administered by intraperitoneal chemohyperthermic perfusion (ICHP) in patients with peritoneal carcinomatosis. 28 patients received MMC 20 mg/m2 intraperitoneally as a perfusion over 60 min. MMC was determined in perfusate, plasma and urine samples with a UV-HPLC method. A compartmental model was used to fit the drug concentrations in plasma and perfusate. Our results showed a mean maximum plasma concentration (Cmax) of 0.14 +/- 0.086 microg/ml with a peak time (Tmax) of 48..7 +/- 5.61 min. The mean area under the curve (AUC) and terminal half-life (t1/2) were 15.8 +/- 9.8 mg x min/L and 83.7 +/- 31.74 min respectively. Clearance (CL) was estimated by fitting the data by a compartmental model and the mean value was 72 +/- 66 L/h. The percent of the dose absorbed was very variable and ranged between 14 and 57% (mean 37 +/- 14%). The mean percentage of dose recovered unchanged in the urine during 24 hours was 7.21 +/- 3.73%. We conclude that ICHP in patients with peritoneal surface malignancies seems to have clinical value since it gives high peritoneal and tumor MMC concentrations with limited systemic exposure and toxicity.

Is a long-term ranitidine-based triple therapy against Helicobacter pylori only a heritage of the past? A prospective, randomized clinicopharmacological study

BACKGROUND

Acid suppression plus two antibiotics is currently considered the gold standard anti-Helicobacter pylori treatment, but the effective role of gastric antisecretory drugs is still poorly understood.

AIMS

To compare a 14-day ranitidine-based triple regimen against Helicobacter pylori with one based on omeprazole, and to study the influence of antisecretory drugs on metronidazole pharmacokinetics in human plasma.

METHODS

A total of 150 dyspeptic H. pylori-infected patients were randomized for ranitidine 300 mg b.d. (RCM group) or omeprazole 20 mg b.d. (OCM group) 14-day triple therapy, with clarithromycin 500 mg b.d. and metronidazole 500 mg b.d. On the eighth day of therapy, metronidazole pharmacokinetics was studied in plasma by high-performance liquid chromatography. The pharmacokinetic parameters (terminal half-life, area under the curve, peak-plasma level, peak time) of metronidazole were computed using standard non-compartmental methods. H. pylori status was monitored before and 4 weeks after the end of therapy by histology, serology and rapid urease test.

RESULTS

On an intention-to-treat basis, eradication rates were 91 and 76% for the RCM and OCM groups respectively (P < 0.02). Significantly different pharmacokinetic parameters of metronidazole were found between the groups: peak-plasma level (P < 0.01) and area under the curve (P < 0.02).

CONCLUSION

Our results show that the RCM regimen was more effective than that based on OCM and that the antisecretory drugs affected metronidazole availability, increasing the efficacy of ranitidine-based regimens.

[Guidelines for the management of HCV infection in HIV-infected patients. Istituto Nazionale per le Malattie Infettive Lazzaro Spallanzani]

It is crucial to ensure an optimal clinical management of HCV infection in HIV-co-infected persons. The reasons for the development of guidelines on HCV-infection treatment in HIV-infected persons arise from the need for a standardised management of HIV/HCV coinfection in our Institute. The aim of these guidelines are: to clarify principles of clinical management of HCV infection in HIV-infected patients to care-providers; to improve the awareness of HIV-infected patients cared for our Institute on current management of HCV infection; to improve the quality of care on this topic. These guidelines, based on Evidence based Medicine principles, have been developed by a panel of experts, who conducted a systematic review of the literature, mainly taking into account current international recommendations. In the present document, the most frequent clinical presentation occurring in the management of HIV/HCV co-infected patients at our Institution are discussed. The adherence to present guidelines and their effectiveness at our Institution, outcome indicators will be evaluated. The present guidelines cannot entirely substitute the judgement of an expert clinician. However, adherence to these guidelines will contribute to the improvement of the standard of care of HIV/HCV-co-infected persons.

A short introduction to pharmacokinetics

Phamacokinetics is proposed to study the absorption, the distribution, the biotransformations and the elimination of drugs in man and animals. A single kinetic profile may be well summarized by Cmax, Tmax, t 1/2 and AUC and, having more than one profile, 8 parameters at least, the mean and standard deviation of these parameters, may well summarize the drug kinetics in the whole population. A more carefull description of the data can be obtained interpolating and extrapolating the drug concentrations with some mathematical functions. These functions may be used to reduce all the data in a small set of parameters, or to verify if the hypotheses incorporated in the functions are confirmed by the observations. In the first case, we can say that the task is to get a simulation of the data, in the second to get a model. The functions used to interpolate and reduce the pharmacokinetic data are the multiexponential functions and the reference models are the compartmental models whose solutions are just the multiexponential functions. Using models, new meaningfull pharmacokinetic parameters may be defined which can be used to find relationships between the drug kinetic profile and the physiological process which drive the drug absorption, distribution and elimination. For example, compartmental models allow to define easily the clearance which is dependent on the drug elimination process, or the volume of distribution which depends on the drug distribution in the tissues. Models provide also an easy way to get an estimate of drug absorption after extravasculare drug administration (bioavailability). Model building is a complex multistep process where, experiment by experiment and simulation by simulation, new hypothesis are proven and disproven through a continuous interaction between the experimenter and the computer.

gammadelta T-cell anergy in human immunodeficiency virus-infected persons with opportunistic infections and recovery after highly active antiretroviral therapy

gammadelta T lymphocytes recognize non-peptidic microbial antigens without antigen processing and major histocompatibility complex (MHC) restriction, representing an early defence mechanism against invading pathogens. As a defective response to non-peptidic antigens was observed in human immunodeficiency virus-positive (HIV+) persons, the aims of this study were twofold: to analyse the incidence of gammadelta T-cell anergy in HIV+ positive patients with opportunistic infections/co-infections (HIV-OIC), and to investigate the role of highly active antiretroviral therapy (HAART) on gammadelta T-cell functions. Peripheral gammadelta T-cell distribution and in vitro reactivity to a non-peptidic mycobacterial antigen, isopentenyl pyrophosphate (IPP), were analysed. gammadelta T-cell subset distribution was altered more in HIV-OIC patients than in asymptomatic HIV+ subjects (HIV-ASY). Specifically, the Vdelta2/Vdelta1 ratio was inverted as a consequence of a decrease in Vdelta2 T-cell number. Moreover, IPP-stimulated Vdelta2 T cells from the HIV-OIC group displayed a major defect in interferon-gamma (IFN-gamma) production. Interestingly, HAART induced a sustained recovery of naive CD45RA+ and CD62L+ T cells and restored gammadelta T-cell function. Accordingly, in vitro CD45RA depletion resulted in gammadelta T-cell hyporesponsiveness. Altogether, the incidence of gammadelta T-cell anergy was increased in HIV-OIC patients and dependent on CD45RA helper function. Moreover, HAART was able to restore gammadelta T-cell reactivity, extending the immune recovery to non-peptide microbial antigens.

[The correlations between color Doppler using a contrast medium and the neoangiogenesis of small prostatic carcinomas]

PURPOSE

To investigate if the use of a contrast agent (Levovist) improves the specificity of US in the diagnosis of prostate carcinoma, having the results of prostate biopsy as the gold standard.

MATERIAL AND METHODS

Thirty patients with physical findings suspicious for prostate carcinoma and PSA ranging 5 ng/mL to 15 ng/mL were examined with transrectal US (TRUS) integrated with the color Doppler mode and contrast agent administration (4 g injected at 4 mL/min: 300 mL concentration).

RESULTS

Based on bioptic and surgical results, 14 prostate carcinomas were found, all of them < 1.2 cm. Conventional US recognized the suspected nodule in 11 cases, with 78% sensitivity and 93% specificity. Color Doppler showed color signals in 8/14 cases, which were peripheral to the lesion or intranodular, but did not add any important finding to those of gray-scale US. In contrast, contrast enhanced studies showed 13/14 carcinomas, which improved sensitivity significantly (92%). Particularly, 11/14 lesions had a typical avascular pattern within the strongly enhanced peripheral gland, while 2 small lesions only exhibited intranodular vessels.

DISCUSSION AND CONCLUSIONS

We compared our results with the Microscopic Angiogenesis Grading System (MAGS) index and found it exceeded 30 in the 11 avascular lesions value indicates microneoangiogenesis. In the other two cases a value < 30 was correlated with a different type of tumor vascularization typical of macroangiogenesis.

[Dysmetabolic syndrome related to HIV-1 protease inhibitors. Review of the literature and personal data]

HIV-positive patients receiving antiretroviral therapy with HIV-1 protease-inhibitors (PI) frequently show insulin-resistance, impaired glucose tolerance, hypertriglyceridaemia and lipodystrophy (LD). LD has often been reported only after the beginning of PI therapy. Some authors link LD to HIV chronic infection, some others suggest that PIs increase pre-existent disturb. Preliminary data of an observational study drawn in IV day-hospital of Spallanzani Institute in Rome showed hypertriglyceridaemia in 36.4% and hyperglycaemia in 11.2% of patients treated with PI. Carr suggests that such drugs should have this lipid-increasing effect because of their inhibition of low density lipoprotein-receptor-related protein, cytoplasmic retinoic-acid binding protein type 1 and P450 3A cytochrome. This theory doesn't explain why both untreated patients and treated with only reverse transcriptase inhibitors show sometimes the same disorders. According to another hypothesis Tumor necrosis factor-alpha, through inhibition of lipoprotein-lipase, would determine high fat-storage in the adipose tissue. Cardiovascular risk factors have always to be assessed before starting a therapy with PI. Glycaemia, triglyceridaemia, cholesterolaemia have to be performed every three months during the treatment and, if necessary, C-Peptide and insulinaemia too. A treatment with lipid-lowering drugs is always recommended in patients with hypertriglyceridaemia > 500 mg/dl and/or hypercholesterolaemia LDL > 190 mg/dl in two following checks. Fibrates have proven to be effective in reducing hypertriglyceridaemia, but there is no certainty that such therapies could have good effects on the LD itself too.

A new model to assess tcpO2 changes during heat-dependent vasodilation: preliminary observations

The transcutaneous pO2 (tcpO2) changes induced by the increase of temperature to 45 degrees C after electrode stabilization at 37 degrees C were continuously recorded. The mathematical analysis of the curve led us to identify three different parameters: the half-slope "b" time, the angular "mT" coefficient and the angular "mb" parameter, which are not simply the expression of the maximum vasodilation capacity but mainly of the dynamic response of the microcirculatory system to skin heating. These parameters derived from the computerized mathematical analysis of the curve can be also obtained by a graphical approach with a very good approximation. The angular "mb" coefficient was shown to possess the highest statistical power in discriminating the POAD patients from normal controls. The clinical relevance and the possible pathophysiological meaning of these preliminary observations have to be confirmed.

Pharmacokinetic and immunogenic behavior of three recombinant human GM-CSF-EPO hybrid proteins in cynomolgus monkeys

MEN 11,300, MEN 11,301, and MEN 11,303 are three recombinant human hybrid proteins that, as has recently been described, induce in vitro erythroid differentiation. This article provides data on their pharmacokinetic and immunogenic behavior after repeated i.v. administration to cynomolgus monkeys at 0.8 or 1.6 micrograms/kg doses. Pharmacokinetic data, obtained after the first administration, showed that the half-life (t1/2) and clearance (CL) values are dose dependent, with no significant differences among the three hybrid proteins. After the tenth administration, MEN 11,300 and MEN 11,301, both a high and low dose, and MEN 11,303 at high dose were undetectable in plasma, whereas MEN 11,303 at the lower dose showed no alteration in its pharmacokinetic profile. Immunologic analyses of plasma provided an explanation for this different pharmacokinetic behavior. In fact, plasma samples from animals treated repeatedly with MEN 11,300 and MEN 11,301 showed specific antibody formation in response to both the high- and the low-dose regimens. These antibodies exerted in vitro a strong neutralizing activity of the hybrid proteins, with a predominant specificity for the erythropoietin (EPO) portion. By contrast, MEN 11,303 at the lower dose did not induce a detectable antibody response whereas the antibodies observed on the high-dose regimen did not exert neutralizing activity against the hybrid proteins nor against granulocyte-macrophage colony-stimulating factor (GM-CSF) or EPO. Hematologic parameters were not affected by the treatments, thus indicating that the anti-EPO neutralizing antibody response does not cross react with the endogenous monkey cytokine. The overall immunogenicity data suggest that among the three fusion proteins, MEN 11,303 could have a lower immunogenic potential.

[Insulin resistance. Receptor and post-receptor abnormalities]

Insulin action starts with binding to a membrane receptor (insulin receptor-tyrosine kinase) and with activating an insulin receptor substrate 1 (IRS-1) and substrate 2 (IRS-2). Insulin receptors interact at least with three cascade reactions, phosphorylating G proteins and IRS-1, that activate PLC "ras" and PI-3-K. NIDDM can be defined as a disease caused by defective transduction of insulin signals and IR as a complex phenotype manifesting itself, emphasized by individual and environmental factors, in the cellular systems of signal transduction. IRS is a syndrome characterized by NIDDM, hypertension, visceral obesity, CHD: the X syndrome. Up to day the described mutations of the insulin-receptor gene are rare (e.g. the leprechaunism): genetic IR. Obesity is the principal cause of IR by receptorial and post-receptorial defects: metabolic IR. The obese skeletal muscle shows a reduction of insulin receptor and IRS-1 phosphorylation and of PI-3-K activation; the scarce expression of these proteins would determine the muscular IR. IR is a pattern of essential hypertension. Hypertension, dyslipidemia and abnormality of glucose metabolism are linked by IR. The so called high erythrocyte Na(+)-Li+ counter-transport is a new biochemical marker for IR and hypertension. These drugs can reduce IR: metformin, sulphonilureas, fibrats, dexfenfluramine, troglitazone, doxazosin, ACE-inhibitors.

Amiloride pharmacokinetics in rat

The kinetics of amiloride was investigated in plasma, urine, faeces and tissues of rats after oral (10 mg/kg) and i.v. (10 mg/kg bolus and 35 microg/h for 4-days infusion) administration. Initially the experimental data were analyzed by a multiexponential model, then a compartmental model was developed to describe the drug kinetics in plasma, urine, faeces and tissues after the i.v. bolus and the oral administration simultaneously. Aim of the model was also to predict the drug kinetics in plasma and tissues of rats after continuous i.v. infusion. The results of the prediction and the discrepancies between prediction and observed data allowed a deeper insight into the pharmacokinetics of amiloride.

Artificial skin equivalent differentiation depends on fibroblast donor site: use of eyelid fibroblasts

Our objective was to construct and explore human skin equivalents from several normal and pathologic donor skin sites to determine if the fibroblast origin influences epidermal differentiation. Also, we wanted to find out if fibroblasts from some donor sites produced epidermis of superior quality for plastic surgery repairs. Skin equivalents were constructed from 15 normal skin specimens, 9 normal eyelid specimens, 15 lesional skin specimens taken from patients with psoriasis, and 4 specimens from keloid scars. Results show that the tissue origin of the donor fibroblasts determines epidermal differentiation and the time period for regeneration. Eyelid fibroblasts were very dependable in establishing well-differentiated skin equivalents in all nine specimens. Our findings contribute to the accumulated knowledge of wound healing and should also be of value in skin grafting, especially when large areas are denuded as in burns, severe trauma, or cancer ablation.

Pharmacokinetics of isosorbide dinitrate in healthy volunteers after 24-hour intravenous infusion

No studies have examined the pharmacokinetics of isosorbide dinitrate (ISDN) after infusion of long duration, even though such infusions are used in patients. We therefore measured ISDN and its active metabolites, isosorbide-5-mononitrate (IS5MN) and isosorbide-2-mononitrate (IS2MN), in plasma of 9 healthy volunteers who received a continuous intravenous infusion of ISDN for 24 hours at a dose rate that lowered diastolic blood pressure by 10% during the first 30 minutes of infusion. All subjects tolerated the infusion except one who experienced intolerable headache. Five subjects received 1 microgram.min-1.kg-1, one 2 micrograms.min-1.kg-1, and two 4 micrograms.min-1.kg-1 ISDN, whereas the full rate of 6 micrograms.min-1.kg-1 was used continuously in one subject. At all infusion rates the plasma concentrations of ISDN were higher at 24 hours than at earlier times, suggesting that a steady-state condition had not been reached at that time. The same was true for the mononitrate metabolites, which reached higher plasma concentrations and were cleared more slowly than the parent compound after the end of the infusion. Apparent elimination half-lives of ISDN, IS2MN, and IS5MN were 67 +/- 10 minutes, 115 +/- 13 minutes, and 272 +/- 38 minutes, respectively. Comparison of low-rate infusions (1 and 2 micrograms.min-1.kg-1) with high-rate infusions (4 and 6 micrograms.min-1.kg-1) showed that the plasma concentration ratios at 24 hours of mononitrate metabolites to parent drug and apparent plasma clearance of ISDN were almost halved at the higher infusion rates.

Endoscopic approach to traumatic visual loss

OBJECTIVE

To review our experience with the use of endoscopic optic nerve decompression in traumatic blindness.

METHOD

We did a retrospective analysis of patients with traumatic blindness that underwent endoscopic decompression of the optic canal to determine postoperative visual acuity and correlate it to preoperative visual loss and intraoperative findings. The setting was a Level I university trauma center. We identified 8 patients treated with both surgery and steroids over a 10-month period beginning in 1993 (Seven males, one female).

RESULTS

Four of six patients with total blindness (no light perception) had improvements in visual acuity. In three patients, visual acuity returned to preinjury levels. One patients with total blindness was operated on 6 weeks after injury and had a visual acuity of 20/800 at 1-year follow-up. Two patients with hand motion preoperatively had improvement in visual acuity. In one patient, vision returned to normal (20/20), and in the other it improved to 20/200). Five patients were operated on after megadose steroid treatment for at least 48 hours failed; four of five noted dramatic improvements in visual acuity.

CONCLUSION

The endoscopic approach may be used to successfully decompress the optic nerve in traumatic blindness.

Multiple genetic lesions in solid tumors: relevance to diagnosis, prognosis, and molecular mechanisms

In recent years, significant progress has been made in identifying characteristic chromosomal and molecular rearrangements associated with several solid tumors. Most solid tumors studied have been found to be characterized by recurrent chromosomal abnormalities that are specific to histologic types. We have studied primary specimens of malignant melanoma, gastrointestinal cancer, renal carcinoma, lung and ovarian cancer, by cytogenetic and molecular means, and we discuss the genetic alterations found. Brief descriptions of the potential clinical utility, and biological relevance changes in these disorders are also discussed.

[The pharmacokinetics of antibiotics: parenteral and oral administration, distribution in the organism, elimination]

The efficacy of antimicrobial therapy is largely dependent on the pharmacokinetics of the drug. Pharmacokinetics is the study of the kinetics, that is of the movements of drugs in the body fluids and tissue cells. Often, despite the complexity of mammalian organism, relatively simple compartmental systems are capable to describe the kinetics of many drugs and to provide a rationale in interpreting the experimental results. As most bacterial infections are localized in tissues, the pharmacokinetic modelling of antimicrobial agents should mainly be devoted to clarify the relationship between plasma and tissue drug levels, the former being easily accessible to sampling and the latter more closely related to therapeutic efficacy. In this paper an introduction to pharmacokinetic modelling is presented and the pharmacokinetics of many antimicrobial drugs is discussed.

Pharmacokinetics of exogenous adenosine in man after infusion

The plasma kinetics of adenosine was investigated in healthy volunteers after a 1 minute infusion of 2.5, 5 and 10 mg (38.79 and 148 micrograms.kg-1 respectively) and after infusion of 200 micrograms.kg-1 in 10 min followed by 400 micrograms.kg-1 in 10 min. As the dose in the 1 min infusion study was increased the mean CL of adenosine decreased (10.7, 4.70 and 4.14 l.min-1, respectively), its mean half-life increased (0.91, 1.24 and 1.86 min, respectively), and the mean volume of distribution did not show any clear trend (8-13 l). After the 20 minute infusion the plasma level of adenosine reached a peak value comparable to that observed after infusion of 5 mg in 1 min (about 0.5 micrograms.ml-1), but the mean clearance and half-life were significantly different (12.1 l.min-1 and 0.63 min respectively). In all the subjects the plasma concentration of adenosine had returned to the baseline value in 5-15 min after the end of the infusion.

Anesthesiologic findings in surgery for the treatment of trauma of the pelvis

The authors discuss the numerical increase in fractures of the acetabulum and the extent of surgical indications for their treatment, emphasizing the modernness and the usefulness of methods used to save blood in this type of surgery, which often involves a considerable loss. Out of 150 operations performed between 1985 and 1990 for trauma of the pelvis, 35% of the patients was not transfused with homologous blood, 25% was transfused with 1 U, 40% with several units (4.7 U on the average). Generally, the average quantity of erythrocytes transfused per patient was 2 U (440 ml).

[Sodium naproxen in postoperative pain in orthopedics. Comparison of 2 different doses]

In order to use etiopathogenetic criteria for the treatment of postsurgical pain, non-steroid anti-inflammatory drugs (NSAIDs) can be used rather than narcotic analgesics. These agents are often classified as peripherally acting analgesic drugs; nevertheless in the last years many pages have who showed a central supraspinal analgesic effect. Sodium naproxen is commonly used in the treatment of postoperative orthopedic pain because of its pharmacokinetic properties. The aim of this study was to evaluate the suitable dosage of sodium naproxen for post-surgical pain relief. Forty patients submitted to foot surgery were randomized into two groups of 20 patients each. At the end of surgery one group of patients (group I) received sodium naproxen 275 mg i.m.; the same dose was administered after 12 hours. A second group (group II) received sodium naproxen 550 mg i.m. at the same time intervals. Based on a Descriptive scale for algometric measurements, the results showed significant differences in analgesic activity for the two treatments. The best results (70% of patients with no pain or slight pain vs 20% of patients) were obtained in the group that received sodium naproxen at the higher dosage (p less than 0.001). No differences were observed in the incidence of side-effects in the two groups. These results are discussed.

The treatment of congenital hip dislocation between the ages of 1 and 3

A total of 81 patients (103 hips) with a diagnosis of congenital hip dislocation were reviewed, who had been treated between one and three years of age. All of the patients were initially treated with adhesive band traction prior to non-surgical reduction, which was performed under general anesthesia using gentle reduction maneuvers followed by immobilization in plaster. Non-surgical reduction was performed in 69 hips (67%), surgical in the remaining 34 (33%). A total of 91 associated surgical procedures were performed for the treatment of residual subluxation. Average follow-up was 12 years (minimum 5, maximum 19). The clinical results of the non-surgical reductions were excellent in 75% of the cases. Radiographically, 48% are hips which have a normal aspect, while 42% have a moderate degree of residual dysplasia or deformity of the femoral epiphysis and of the acetabulum. Hips that were initially classified as grade III dislocations show fair results. Hips treated non-surgically included 11 cases of avascular necrosis (16%); recovery was adequate. Hips treated surgically included 14 cases of avascular necrosis (30%), which was more accentuated in those hips that had initially been treated elsewhere, and in those classified as grade III. The clinical and radiographic results obtained for the hips treated surgically demonstrate poor results in 17% of the cases (6 out of 34), as a consequence of types III and IV osteochondrosis. It may be concluded that in this age group congenital hip dislocation is best treated by non-surgical reduction, possibly followed by surgery of the femur and acetabulum. Surgical reduction was only indicated when conservative methods failed.

Pharmacokinetics of heptastigmine in rats

Heptastigmine is a new long acting cholinesterase inhibitor that affects behaviour in a number of cognitive tests in animals. We have studied its pharmacokinetics in rats: plasma kinetics were evaluated after single intravenous dose (2 mg/kg), intramuscular (4 mg/kg) and oral (4 and 8 mg/kg) administration. Tissue distribution (heart, liver, kidney and brain) was studied after single intramuscular (4 mg/kg) and oral (8 mg/kg) administration. Plasma and tissue kinetics were also investigated after repeated oral doses (8 mg/kg b.i.d. for 7 days). Heptastigmine levels in plasma and tissues were determined using an HPLC method with an electrochemical detector. After a single dose, heptastigmine remained for a long time in plasma (the terminal half-life was about 12 h), distributed widely in tissues (the volume of distribution was about 61) and brain concentrations were very high (4-22 times those found in plasma). After repeated oral doses, the drug levels increased in plasma and, to a lesser extent, in liver and kidney.

Pharmacokinetics of rufloxacin in healthy volunteers

The plasma and urine kinetics of rufloxacin were assessed in healthy volunteers after single (100, 200, 400 and 800 mg) and multiple (300 mg followed by 150 mg daily, Group 1, and 400 mg followed by 200 mg daily, Group 2) oral doses. The kinetics of a single oral dose of 800 mg was assessed in fasting and non-fasting subjects to assess the influence of food intake on drug absorption. The AUCs were 134, 266 and 375 micrograms.h.ml-1 after 100, 200 and 400 mg, respectively. The AUC after 800 mg p.o. was 715 micrograms.h.ml-1 in fasting subjects and 614 micrograms.h.ml-1 in non-fasting subjects. The parameters of the model and the mean renal clearance values indicated some departure from linearity in rufloxacin kinetics. After multiple doses the plasma drug levels during the 6th treatment day were similar to those after the first dose in Group 1 and were about 30-40% higher after the first dose in Group 2. The half-lives after the last dose were much shorter than those estimated in the single dose studies (33-36 h and 50-80 h, respectively).

Pharmacokinetics of bamifylline during chronic therapy

The pharmacokinetics of bamifylline (Briofil) has been studied in 6 healthy volunteers both after acute and chronic administration. The kinetic variables were similar both after the first dose and after chronic treatment and no significant accumulation of the drug was observed after 7 days of therapy with bamifylline (600 mg b.i.d.). The analysis of minimal concentrations of bamifylline did not yield evidence of circadian variation in the kinetics of this drug; large differences among subjects and within each subject on different days may be explained by changes in drug bioavailability. Very low plasma levels of bamifylline were observed at the end of the dosing intervals in 50% of the cases; this observation does not necessarily invalidate the efficacy of this dosage regimen because the active metabolite of bamifylline (AC119) might contribute to the bronchodilator activity of this drug.

The pharmacokinetics of aztreonam and penetration into the bronchial secretions of critically ill patients

The pharmacokinetics of aztreonam were studied in ten critically ill intubated patients with lower respiratory tract infections. Serum and urinary concentrations of the drug and its penetration into bronchial secretions after a 2-g intravenous bolus were measured. Using a two-compartment linear model a terminal half-life of 1.87 + 0.46 h was determined. No interpatient differences were found for half-life values, AUC or volume of distribution, except in the case of one obese patient. The greatest variability was observed in the clearance values, and in particular the extrarenal clearance which ranged from 0.3 to 9.6 1/h. Maximum concentrations in bronchial secretions were reached very quickly in the 2 h after drug administration, with a range of 4.8-18.7 mg/l. No accumulation of aztreonam after repeated doses was detected.

Doxorubicin toxicity and pharmacokinetics in old and young rats

Doxorubicin (Dx) toxicity was compared in old (24 months) and young (6 weeks) Crl:CD(SD) BR male rats, and a clear age-related increase was found. The mortality of all animals receiving a single i.v. Dx dose was followed for 270 days. Old rats died after doses of 2.5 mg/kg, while young animals died after doses two times higher, 5 mg/kg. In old rats body weight loss started 10 to 15 days after Dx, compared to 50 to 80 days for young animals. In young and old rats pharmacokinetic and metabolic studies of Dx were conducted in vivo and in the liver perfusion model. Peak levels of Dx and areas under the time/concentration curves (AUC) in serum and in several tissues of old rats were 1.5 to 2 times higher than in young rats. Concentrations of Dx metabolites in serum and tissues (doxorubicinol, Dxol, and doxorubicinone, Dxone) in young and old rats were not noteworthy. However, higher percentages of Dxone than Dxol were found in both groups in vivo and in vitro. Old livers appeared to produce more Dxone as a percentage, particularly in the bile, which was higher. Urinary elimination of Dx markedly slowed with age; only small amounts of the metabolites were eliminated in urine. In vivo and in vitro availability of Dx and its metabolites is discussed in view of their possible role in the greater toxicity observed in 24-month-old rats.

Metabolism and disposition of intravenously administered acetyl-L-carnitine in healthy volunteers

The pharmacokinetics of acetyl-L-carnitine hydrochloride were investigated in 6 healthy volunteers of both sexes after i.v. injection of 500 mg of the drug, expressed as inner salt. Plasma concentrations and urinary excretion of acetyl-L-carnitine (A), L-carnitine (B) and total acid soluble L-carnitine fraction were evaluated over a period lasting from 24 h before to 48 h after the administration. Plasma concentrations of A increased quickly after administration and then declined reaching base values within 12 h. Conversely, plasma concentrations of B rose more slowly, reaching a peak in 30-60 min, and then declined to base values within 24 h. Most of the injected dose of acetyl-L-carnitine was recovered in the urine during the first 24 h after administration as B and A. Mean renal clearance of both A and B during the first 12 h after injection was higher than the base values, suggesting the presence of a saturable tubular reabsorption process which may counterbalance major changes occurring in plasma concentrations of L-carnitine pattern.

Pharmacokinetics of mifentidine after single and multiple oral administration to healthy volunteers

1. The pharmacokinetics of mifentidine, a new long acting histamine H2-receptor antagonist, were studied using two protocols. 2. In one study, on 5 different days six normal male subjects were given 2.5, 5, 10, or 20 mg mifentidine or placebo orally 60 min before starting a 3 h continuous gastric aspiration during which time blood samples were taken for measurement of mifentidine concentration. 3. The area under the curves of mifentidine plasma levels (AUC) vs time for the four doses was linearly related to the dose for each individual subject (r = 0.972, P less than 0.001). After doses of 2.5, 5, 10 and 20 mg, mifentidine reduced hydrogen ion output by respectively 36, 37, 60 and 75% and secretory volume by 1, 17, 40, and 47%. The effects at the two highest doses were statistically significant. AUC was correlated positively with the percentage reduction in hydrogen ion output (r = 0.802, P less than 0.001) and volume (r = 0.834, P less than 0.001) over a 3 h period. 4. In the second study, the pharmacokinetics were evaluated after once-daily treatment for 14 days in seven subjects given 10 mg and in seven others subjects given 20 mg. 5. After multiple dosing, renal clearance was similar for the two doses (11.6 +/- 2.11 l h-1 for the low dose and 17.0 +/- 2.0 l h-1 for the high dose). Plasma half-life (t1/2 lambda 2) was 16.0 +/- 3.0 h after the 10 mg dose and 11.9 +/- 1.2 h after 20 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of enteric-coated aspirin and inhibition of platelet thromboxane A2 and vascular prostacyclin generation in humans

We evaluated whether an enteric-coated aspirin formulation showed a "presystemic" component in its antiplatelet effect and if so would spare vascular cyclooxygenase. In six healthy volunteers, 30 to 45 minutes after ingestion of 325 mg enteric-coated aspirin, platelet thromboxane A2 generation was inhibited by about 20% before any drug could be detected in the peripheral venous blood. A further decline in thromboxane A2 generation occurred with appearance of aspirin in blood between 60 and 240 minutes. No presystemic component could be detected after 325 mg aspirin tablets. Ten patients undergoing saphenectomy received 325 mg of either aspirin tablet or enteric-coated aspirin; 12 hours later platelet thromboxane A2 and peripheral vascular prostacyclin generation were significantly reduced by 98% and 58%, respectively. The effects of the two aspirin formulations were not different. Aspirin formulations with "presystemic" component in their antiplatelet effect may not necessarily result in sparing of peripheral vascular cyclooxygenase.

Lipophilicity and disposition of 1-aryl-piperazines in the rat

The disposition of eight 1-aryl-piperazines was investigated in rats after i.v. administration. The concentration of 1-aryl-piperazine in body fluids and tissues was determined by h.p.l.c. or electron-capture g.l.c. Correlations of kinetics and physiological parameters with the lipophilicity of each 1-aryl-piperazine, determined by h.p.l.c. retention on a reverse-phase C18 column at neutral pH, were investigated. Binding to rat plasma proteins varied within the series, increasing with lipophilicity. For the majority of the derivatives the blood-to-plasma ratio was close to unity, implying an almost equal distribution between erythrocytes and plasma. The most lipophilic 1-aryl-piperazine of the series partitioned more into erythrocytes. The eight compounds differed widely in Vss and total Cl values and as a general trend both values increased with lipophilicity. The percentage of the dose excreted unchanged in the urine decreased progressively with increasing lipophilicity. 1-Aryl-piperazines were distributed extensively in all the tissues examined, concentrating particularly in the eliminating organs and lung. They easily entered the rat brain, Cmax values generally being reached within five minutes of parenteral injection. 1-Aryl-piperazine brain uptake increased with lipophilicity.