Menstrual cycle variability in midazolam pharmacokinetics

Activity of cytochrome P450 3A4 (CYP3A4), the most abundant human P450 isoform and responsible for metabolizing approximately half of all therapeutic agents, has been speculated to vary during the menstrual cycle. This investigation evaluated CYP3A4 activity during the menstrual cycle, using midazolam clearance as a metabolic probe. Midazolam (1 mg i.v.) was administered to nonsmoking, nonpregnant female volunteers (N = 11, age 26 +/- 5 years) with normal menstrual cycles on three separate occasions during the same cycle: days 2 (menstrual phase), 13 (estradiol peak), and 21 (progesterone peak). Venous plasma midazolam concentrations were determined by gas chromatography-mass spectrometry. Midazolam clearance was determined by noncompartmental and compartmental analysis. Midazolam plasma disposition did not differ between phases of the menstrual cycle. There was no significant difference in any measure of midazolam clearance. Noncompartmental clearances (mean +/- SD) were 7.36 +/- 2.73, 6.34 +/- 3.59, and 6.23 +/- 2.04 ml/kg/min, respectively, on days 2, 13, and 21 of the menstrual cycle. These results suggest no difference in hepatic CYP3A4 activity on menstrual cycle days 2, 13, and 21. Consideration of menstrual cycle variability in the metabolism of CYP3A4 substrates does not appear indicated in the dosing or design of clinical trials.

Development of an automated mass spectrometry system for the quantitative analysis of liver microsomal incubation samples: a tool for rapid screening of new compounds for metabolic stability

There is a continuing need for increased throughput in the evaluation of new drug entities in terms of their pharmacokinetic parameters. One useful parameter that can be measured in vitro using liver microsomal preparations is metabolic stability. In this report, we describe an automated system that can be used for unattended quantitative analysis of liver microsomal samples for a series of compounds. This system is based on the Sciex API 150 (single quadrupole) liquid chromatography/mass spectrometry system and utilizes 96-well plate autosampler technology as well as a custom-designed AppleScript which executes the on-line data processing and report generation. It has the capability of analyzing at least 75 compounds per week or 300 compounds per month in an automated fashion.

Posttransplant lymphoproliferative disorders and gastrointestinal manifestations of Epstein-Barr virus infection in children following liver transplantation

BACKGROUND

Epstein-Barr virus (EBV) infection is common after liver transplantation in children and is associated with the risk of posttransplant lymphoproliferative disorders (PTLD).

METHODS

This retrospective study examined the frequency of gastrointestinal (GI) symptoms and the risk of PTLD in pediatric liver recipients who developed symptomatic EBV infection. We reviewed 172 children who received orthotopic liver transplants between March 1988 to December 1994. Twenty-two cases were retransplants. The mean age at transplantation was 3.7 years (range, 0.1-17 years). The immunosuppressive regimens consisted of induction therapy with Minnesota antilymphocyte globulin/antithymocyte globulin/OKT3 in most cases and maintenance therapy with prednisone and either cyclosporine or tacrolimus (FK506).

RESULTS

After 1 year of minimum follow-up, 54 of 172 patients had symptomatic EBV infections (confirmed by serology, histology, or whole blood polymerase chain reaction. At the time of infection, 38.5% (21/54) had either diarrhea or GI bleeding or both. PTLD developed in 11 patients (6.4%). The incidence of PTLD was 42.9% (9/21) when GI bleeding or diarrhea was associated with EBV infections, compared with 6.1% (2/33) when EBV infection was not associated with GI symptoms. Seven of 10 (70%) patients with GI bleeding and 2 of 11 (18.2%) with diarrhea developed PTLD. Of seven patients examined by endoscopy for GI bleeding, two had biopsy-proven PTLD of the GI tract, whereas one of two patients examined by endoscopy for diarrhea had biopsy-proven PTLD.

DISCUSSION

In summary, a high incidence of PTLD was found in patients who developed GI bleeding or diarrhea associated with EBV infection after pediatric liver transplantation. In these patients, endoscopy and biopsy may lead to early diagnosis of PTLD.

Identification of BCR-ABL fusion on chromosome 9 by fluorescence in situ hybridization in two chronic myeloid leukemia cases

We present two cases with hidden Philadelphia translocations that resulted from an insertion and a complex translocation. These cases were unusual in having the BCR/ABL fusion localized to chromosome 9q34. A review of cases with these uncommon presentations of BCR/ABL and prognostic presentation is presented.

Bottlebrush dendritic endings and large dendritic fields: motion-detecting neurons in the tectofugal pathway

In avian and mammalian brains, visual information from the retina is conveyed to the telencephalon via two separate pathways: the thalamofugal and the tectofugal pathways. Recently, Karten et al. ([1997] J. Comp. Neurol. 387:449-465) examined a portion of the tectofugal pathway, the projection from the optic tectum to the nucleus rotundus thalami, in pigeons. They defined two distinct subpopulations of tectal neurons projecting from the stratum griseum centrale (SGC; tectal layer 13) to specific divisions of the rotundus. The goal of this study in chick was to verify the existence of the type I and type II SGC neurons, as defined by Karten et al., and then examine in greater detail the connectivity and morphology of these SGC neurons. Furthermore, our results suggest how the unique morphological characteristics of SGC neurons contribute to the large receptive fields (20-50 degrees) found in physiological recordings and the SGC neuronal response to extremely small (ca. 0.05 degree), fast-moving (100 degrees/second) stimuli. By injecting retrograde tracer into various divisions of the chick rotundus, we verified that, indeed, the chick did possess type I and type II SGC neurons, as well as a "new" type of SGC neuron, type III, that is not found in the pigeon. We then used intracellular cell-filling techniques to define further these three types of SGC neurons. Our examination revealed the following: Type I SGC neurons had large, circular dendritic fields (average diameter, 1,725 microns) composed of smooth dendrites and ending in spine-rich, bottlebrush endings located in retinorecipient tectal layer 5b; type II SGC neurons had elliptical dendritic fields (average 1,447 microns) and dendritic endings located never more superficially than tectal layer 8; and type III SGC neurons had large dendritic fields (average 1,800 microns) of unknown shape and bottlebrush dendritic endings located in retinorecipient tectal layer 4. We suggest that the neuronal features of the SGC neurons (i.e., bottlebrush dendritic endings and large dendritic fields) are key morphological characteristics for the detection of motion within the tectofugal pathway. Furthermore, because neurons with similar morphology have also been found in the tecta of both mammals and reptiles, we suggest that these neuronal features are fundamental components of a phylogenetically conserved system used for the "extrastriate" detection of motion in vertebrates.

Use of power Doppler in pediatric neurosonography: a pictorial essay

In pediatric neurosonography, conventional color Doppler imaging has been the primary adjunct to routine gray-scale imaging. Power Doppler sonography is a relatively recent development that does not have the limitations of conventional color Doppler ultrasound. The power Doppler technique measures the energy of moving red blood cells instead of the velocity and direction of flow. Advantages of this technique include increased sensitivity for identifying flow in slow-flow states, more complete evaluation of a vessel, and more accurate evaluation of the course of the vessel. Power Doppler sonography is helpful in evaluation of the neonatal brain in a variety of clinical situations: identifying the exact locations of extraaxial fluid collections, differentiating intraventricular clot from normal choroid plexus, detecting intraventricular hemorrhage, and demonstrating asymmetries in cerebral perfusion. However, in certain difficult cases, use of both conventional color Doppler sonography and power Doppler sonography produces increased diagnostic accuracy because these techniques furnish complementary information.

Endotracheal flumazenil: a new route of administration for benzodiazepine antagonism

The purpose of this study was to determine if flumazenil is absorbed from broncho-pulmonary tissue after intratracheal administration and whether therapeutically significant plasma concentrations can be obtained. Six elective surgical patients received a dose of 1.0 mg flumazenil in 10 mL saline intratracheally during general anesthesia. Blood samples were drawn for 6 hours after administration and plasma concentrations were determined by gas chromatography-mass spectrometry (GC-MS). An average peak plasma flumazenil concentration of 65.9 +/- 43.1 ng/mL was attained within 1 minute after administration. No patients reported chest discomfort or dyspnea upon awakening and there were no other side effects noted. Administration of flumazenil via an endotracheal tube results in rapid attainment of therapeutic blood levels.

Investigating psychosocial aspects of participation in early anti-cancer drug trials: towards a choice of methodology

This paper presents the methodological approach and research methods chosen to explore psychosocial aspects of participation in early anti-cancer drug trials from the perspective of those actually involved. The paper describes how an appropriate methodology, or principles of reasoning behind the choice of research methods, emerged. The choice of methodology was based on three elements: first, an understanding of the competing philosophies about how research can be approached and conducted; second, the author's view of the subject area; and third, a consideration of previous research approaches which have investigated psychosocial aspects of cancer clinical trials. A qualitative methodology situated within an interpretative paradigm was eventually chosen as the most appropriate means of exploring trial participants' experiences and the aim and objectives of the research were developed within this methodological framework.

Effects of oral tolerance induction by myelin basic protein on Vbeta8+ Lewis rat T cells

Encephalitogenic T cells from Lewis rats use a restricted T cell receptor (TCR) gene combination, Vbeta8.2 and Valpha2. The oral administration of myelin basic protein (MBP) to Lewis rats prior to encephalitogenic challenge results in a marked inhibition of clinical neurologic signs of encephalitis, reduced central nervous system pathology, suppressed T cell reactivity to MBP, and decreased serum anti-MBP antibody responses. The present study determined the TCR Vbeta8 gene usage in rats rendered orally tolerant to MBP as compared with vehicle-fed or unfed controls. Total RNA was extracted from lymph node cells (LNC), Northern blots run, and hybridizations performed using a rat beta chain V region probe positive for Vbeta8.2. The results indicate that feeding MBP results in a decrease in Vbeta8+ TCR RNA expression in lymph nodes draining the site of encephalitogenic challenge. T cell proliferation was reduced in LNC of tolerized rats relative to control rats. No change in the Vbeta8+ TCR RNA expression or MBP reactivity was observed in the mesenteric lymph nodes (MLN) of vehicle-fed or MBP-fed rats, although an increase in cell number was found in the MLN of both groups. These results suggest that the mechanisms of orally induced tolerance involve local clonal deletion or migration of Vbeta8+ T cells, of which MBP-specific T cells are a part.

Integrin alpha v beta 6 enhances coxsackievirus B1 lytic infection of human colon cancer cells

Viral entry into host cells depends upon specific interactions between virus attachment proteins and cell surface receptors that enable virus binding and internalization of virus and/or the virus-receptor complex. We have recently reported that the ubiquitous cell surface molecule, decay-accelerating factor (DAF), is a major cell attachment receptor for Coxsackieviruses B1, B3, and B5. However, DAF permits only virus binding and not virus internalization, invoking the presence of secondary or accessory receptors. Among the known receptors for enteroviruses are members of the cell adhesion molecule family known as integrins. In the present study, we found that expression of the epithelial-restricted integrin, alpha v beta 6, on colonic epithelial cells significantly enhanced Coxsackievirus B1-mediated cell lysis. Importantly, the viral-mediated cell killing required the presence of the 11-amino-acid C-terminal cytoplasmic extension unique to the beta 6 subunit, providing the first evidence of regulation of viral infectivity by integrin cytoplasmic domains. These results indicate that alpha v beta 6 expression on intestinal epithelial cells critically affects Coxsackievirus B1 infectivity. This may be essential in the conversion of asymptomatic enterovirus infection into clinically apparent disease.

Elevated levels of circulating cell adhesion molecules in uncomplicated essential hypertension

Elevated levels of circulating soluble cell adhesion molecules are associated with the development of cardiovascular disease. We tested the hypothesis that circulating levels of soluble cell adhesion molecules are elevated in older men with uncomplicated essential hypertension, which may contribute to the increased risk of atherosclerosis in this population. Circulating levels of soluble intercellular adhesion molecule-1, vascular adhesion molecule-1, and E-selectin were measured in 11 hypertensive (69+/-1 years) and ten normotensive (65+/-1 years) older men who were free of overt atherosclerotic disease, diabetes, and dyslipidemia. The hypertensive subjects had higher (P < .05) circulating levels of soluble intercellular adhesion molecule-1 (232.4+/-16.5 v 189.8+/-11.1 ng/mL) and vascular adhesion molecule-1 (737.3+/-65.6 v 565.7+/-46.8 ng/mL) compared with their normotensive peers. However, there was no difference in the levels of soluble E-selectin between the hypertensive (51.1+/-3.9 ng/ mL) and normotensive (48.8+/-6.6 ng/mL) subjects. Univariate analysis revealed a positive correlation between soluble intercellular adhesion molecule-1 and both systolic (r = 0.50, P = .02) and diastolic (r = 0.49, P = .03) blood pressure. In addition, soluble vascular adhesion molecule-1 was positively correlated with age (r = 0.60, P = .004) and systolic blood pressure (r = 0.43, P = .05). The results of this study support the hypothesis that circulating levels of soluble cell adhesion molecules are elevated in older men with uncomplicated essential hypertension.

Establishing a programme for continuous ambulatory infusion chemotherapy

BACKGROUND

The development of venous access devices (VADs) and portable infusion pumps has enabled chemotherapy to be administered continuously within the home environment.

AIM

The objective of this study was to describe the experience of establishing an ambulatory chemotherapy programme for patients receiving protracted infusions (PVIs) of 5-fluorouracil (5-FU).

METHODS

The files of all patients receiving PVI 5-FU as a component of their treatment for gastrointestinal malignancy were reviewed. The types of VADs, infusion pump systems and their management were documented. Information packages and education programmes were developed for patients.

RESULTS

Seventy-four patients with gastrointestinal cancer were studies. At the end of the period the Portacath was the preferred VAD, while both pumps used were found to have advantages and disadvantages. The choice of pump was decided more by patient preference than systematic differences in performance of the pumps.

CONCLUSIONS

The findings in this review confirm that, with close attention to the potential pitfalls of ambulatory chemotherapy, an acceptable service can be provided.

Regression of proximal deep venous thrombosis is associated with fibrinolytic enhancement

PURPOSE

Recanalization after acute lower limb deep venous thrombosis (DVT) is well documented, but the precise mechanism and timing of these events has not been well characterized. Regression of DVT has been presumed to result from activation of the endogenous fibrinolytic system. This study was performed to compare measurements of the enzymatic components of the intrinsic fibrinolytic system (tissue plasminogen activator [tPA], plasminogen activator inhibitor [PAI-1]) with the observed morphologic changes in thrombosed venous segments using venous duplex ultrasound scanning (VDUS) at intervals after diagnosis of acute DVT.

METHODS

Nineteen patients with acute DVT underwent serial VDUS to assess regression of thrombus at intervals of 1 to 2 weeks, 3 to 6 weeks, 8 to 12 weeks, and 24 to 36 weeks. The extent of thrombus in each limb was quantitated at each interval by VDUS of the residual thrombus present in each of five major axial venous segments: the common femoral, superficial femoral, profunda femoris, popliteal, and tibial veins. Thrombus scores for the group at each interval were compared with baseline scores at diagnosis to calculate the percent residual thrombus. Endogenous fibrinolytic activity was determined at the same intervals by serologic assay of the biologic activities of tPA and its inhibitor PAI-1.

RESULTS

Thrombus regression was evident by VDUS at 1 to 2 weeks and progressed such that only 26% of residual thrombus remained at 24 to 36 weeks. Complete resolution of thrombus occurred in 10 of 18 patients (56%) who completed the 9-month study. Baseline mean tPA activity was 0.60 +/- 0.07 IU/ml and increased to 1.31 +/- 0.26 IU/ml at 1 to 2 weeks (p = 0.014). tPA activity remained significantly elevated through the 8 to 12 week interval and returned to baseline at 24 to 36 weeks. PAI-1 activity was elevated relative to an age-matched population at baseline (23.1 +/- 1.8 AU/ml) but remained unchanged throughout the study period. Progression of thrombus was observed in three patients (15.8%). Patients who experienced propagation of thrombus did not have the increased tPA activity that appeared to mark activation of intrinsic fibrinolysis.

CONCLUSIONS

Regression of acute DVT begins early and continues for at least 9 months. It is accompanied by significant enhancement of the endogenous fibrinolysis, which appears to be primarily mediated by increased tPA activity. Patients who have thrombus propagation in spite of standard antithrombotic therapy may have failure of activation of endogenous fibrinolysis.

Two distinct populations of tectal neurons have unique connections within the retinotectorotundal pathway of the pigeon (Columba livia)

The tectofugal pathway is a massive ascending polysynaptic pathway from the tectum to the thalamus and then to the telencephalon. In birds, the initial component of this pathway is known as the tectorotundal pathway; in mammals, it is known as the tectopulvinar pathway. The avian tectorotundal pathway is highly developed; thus, it provides a particularly appropriate model for exploring the fundamental properties of this system in all amniotes. To further define the connectivity of the tectorotundal projections of the tectofugal pathway, we injected cholera toxin B fragment into various rotundal divisions, the tectobulbar projection, and the ventral supraoptic decussation of the pigeon. We found intense bilateral retrograde labeling of neurons that stratified within layer 13 and, in certain cases, granular staining in layer 5b of the optic tectum. Based on these results, we propose that there are two distinct types of layer 13 neurons that project to the rotundus: 1) type I neurons, which are found in the outer sublamina of layer 13 (closer to layer 12) and which project to the anterior and centralis rotundal divisions, and 2) type II neurons, which are found in the inner sublamina of layer 13 (closer to layer 14) and which project to the posterior and triangularis rotundal divisions. Only the labeling of type I neurons produced the granular dendritic staining in layer 5b. An additional type of tectal neuron was also found that projected to the tectobulbar system. We then injected Phaseolus vulgaris-leucoagglutinin in the optic tract and found that the retinal axons terminating within tectal layer 5b formed narrow radial arbors (7-10 microm in diameter) that were confined to layer 5b. Based on these results, we propose that these axons are derived from a population of small retinal ganglion cells (4.5-6.0 microm in diameter) that terminate on the distal dendrites of type I neurons. This study strongly indicated the presence of a major bilateral oligosynaptic retinotectorotundal pathway arising from small retinal ganglion cells projecting to the rotundus with only a single intervening tectal neuron, the proposed type I neuron. We suggest that a similar organization of retinotectopulvinar connections exist in reptiles and in many mammals.

Active surveillance after orchiectomy for nonseminomatous testicular germ cell tumors: late relapse may occur

OBJECTIVES

To review the outcome of men with Stage I nonseminomatous germ cell tumors managed with a policy of active surveillance following orchiectomy.

METHODS

The clinical records of all men with Stage I nonseminomatous germ cell tumors seen at Royal Prince Alfred Hospital, Australia between 1982 and 1995 were reviewed. Data were obtained concerning the histologic type of tumor, levels of serum tumor markers, relapse and subsequent treatment, and survival.

RESULTS

Seventy-seven patients were entered into the active surveillance protocol between 1982 and 1995. With a minimum follow-up of 2 years, 27 (35%) have relapsed, with a median time to relapse of 5 months. Two late relapses occurred at 37 and 57 months after diagnosis. Relapses occurred most commonly in the retroperitoneal lymph nodes, with the lungs the second most common site. Following treatment with chemotherapy and surgery, all patients achieved complete remission, with 1 patient subsequently relapsing and ultimately dying of progressive tumor. One other patient died of acute myeloid leukemia, thought to be secondary to chemotherapy. Overall, 75 patients (97%) remain alive and free of disease.

CONCLUSIONS

Active surveillance is a safe and effective approach to the management of Stage I nonseminomatous germ cell tumors. Although most relapses occur within the first 2 years, late relapses may occur.

Ectopic induction of tendon and ligament in rats by growth and differentiation factors 5, 6, and 7, members of the TGF-beta gene family

Little is known about the regulatory signals involved in tendon and ligament formation, and this lack of understanding has hindered attempts to develop biologically based therapies for tendon and ligament repair. Here we report that growth and differentiation factors (GDFs) 5, 6, and 7, members of the TGF-beta gene superfamily that are most related to the bone morphogenetic proteins, induce neotendon/ligament formation when implanted at ectopic sites in vivo. Analysis of tissue induced by GDF-5, 6, or 7, containing implants by currently available morphological and molecular criteria used to characterize tendon and ligament, adds further evidence to the idea that these GDFs act as signaling molecules during embryonic tendon/ligament formation. In addition, comparative in situ localizations of the GDF-5, 6, and 7 mRNAs suggest that these molecules are important regulatory components of synovial joint morphogenesis.

Potential effect of cyclosporin A in formation of cholesterol gallstones in pediatric liver transplant recipients

Recent advancements in liver transplantation have resulted in extended survival both for grafts and recipients. Such improvement, together with the shortage of donor organs has prompted expansion of the donor pool to include less than ideal donors, especially in life-threatening situations. The use of older liver donors has been associated with lower long-term survival. However, potential morbidity such as gallstone formation has not been explored. We analyzed bile composition in a child who developed cholesterol gallstones in the proximal bile duct two years after undergoing emergency liver transplantation with a liver from a 78-year-old donor. Oral administration of ursodeoxycholic acid (ursodiol) shifted the cholesterol composition of the bile from a supersaturated, potentially crystallized state to a liquid (micellar) state. Unlike cyclosporin A, FK506 showed an increase in the proportion of chenodeoxycholic acid and a decrease in the proportion of cholic acid, and thus may exhibit minimal or no hepatotoxic effect. Thus, in donor livers with factors known to be associated with cholesterol gallstone formation (such as age, sex, or obesity), one may consider analyzing the bile composition at the time of procurement. Depending on cholesterol and bile acid composition the use of FK506 with or without addition of ursodeoxycholic acid may be warranted.

The role of cytochrome P450 3A4 in alfentanil clearance. Implications for interindividual variability in disposition and perioperative drug interactions

BACKGROUND

There is considerable unexplained variability in alfentanil pharmacokinetics, particularly systemic clearance. Alfentanil is extensively metabolized in vivo, and thus systemic clearance depends on hepatic biotransformation. Cytochrome P450 3A4 was previously shown to be the predominant P450 isoform responsible for human liver microsomal alfentanil metabolism in vitro. This investigation tested the hypothesis that P450 3A4 is responsible for human alfentanil metabolism and clearance in vivo.

METHODS

Nine healthy male volunteers who provided institutionally approved written informed consent were studied in a three-way randomized crossover design. Each subject received alfentanil (20 micrograms/kg given intravenously) 30 min after midazolam (1 mg injected intravenously) on three occasions: control; high P450 3A4 activity (rifampin induction); and low P450 3A4 activity (selective inhibition by troleandomycin). Midazolam is a validated selective in vivo probe for P450 3A4 activity. Venous blood was sampled for 24 h and plasma concentrations of midazolam and alfentanil and their primary metabolites 1'-hydroxymidazolam and noralfentanil were measured by gas chromatography-mass spectrometry. Pharmacokinetic parameters were determined by two-stage analysis using both noncompartmental and three-compartment models.

RESULTS

Plasma alfentanil concentration-time profiles depended significantly on P450 3A4 activity. Alfentanil noncompartmental clearance was 5.3 +/- 2.3, 14.6 +/- 3.8, and 1.1 +/- 0.5 ml.kg-1.min-1, and elimination half-life was 58 +/- 13, 35 +/- 7, and 630 +/- 374 min, respectively, in participants with normal (controls), high (rifampin), and low (troleandomycin) P450 3A4 activity (means +/- SD; P < 0.05 compared with controls). Multicompartmental modeling suggested a time-dependent inhibition-resynthesis model for troleandomycin effects on P450 3A4 activity, characterized as k10(t) = k10[1-phi e-alpha(t-tzero)], where k10(t) is the apparent time-dependent rate constant, k10 is the uninhibited rate constant, phi is the fraction of P450 3A4 inhibited, and alpha is the apparent P450 3A4 reactivation rate. Alfentanil clearance was calculated as V1 k10 for controls and men receiving rifampin, and as V1.average k10(t) for men receiving troleandomycin. This clearance was 4.9 +/- 2.1, 13.2 +/- 3.6, and 1.5 +/- 0.8 ml.kg-1.min-1, respectively, in controls and in men receiving rifampin or troleandomycin. There was a significant correlation (r = 0.97, P < 0.001) between alfentanil systemic clearance and P450 3A4 activity.

CONCLUSIONS

Modulation of P450 3A4 activity by rifampin and troleandomycin significantly altered alfentanil clearance and disposition. These results strongly suggest that P450 3A4 is the major isoform of P450 responsible for clinical alfentanil metabolism and clearance. This observation, combined with the known population variability in P450 3A4 activity, provides a mechanistic explanation for the interindividual variability in alfentanil disposition. Furthermore, known susceptibility of human P450 3A4 activity to induction and inhibition provides a conceptual framework for understanding and predicting clinical alfentanil drug interactions. Finally, human liver microsomal alfentanil metabolism in vitro is confirmed as an excellent model for human alfentanil metabolism in vivo.

Transition to post-operative epidural or patient-controlled intravenous analgesia following total intravenous anaesthesia with remifentanil and propofol for abdominal surgery

Remifentanil is an ultrashort acting mu opioid, well suited to total intravenous (i.v.) anaesthesia. Pain immediately following emergence from anaesthesia is a potential problem because of the rapid offset. This study investigated the transition from remifentanil/propofol total intravenous anaesthesia to post-operative analgesia with epidural or patient controlled analgesia morphine in 22 patients undergoing major abdominal surgery. A remifentanil post-operative infusion initiated during emergence was titrated in the recovery room for 30 min, at which time 14% of patients had a pain score of 2 and 86% had pain scores of 0 or 1 (0 = no pain; 1 = mild pain; 2 = moderate pain; 3 = severe pain), at a mean infusion rate of 0.086 microgram kg-1 min-1. A smooth transition was then made to either epidural analgesia or patient controlled analgesia with morphine; pain scores were not significantly changed during the transition. Nausea occurred in 16 of the 22 patients, but only following administration of morphine. Epidural analgesia produced significantly lower pain scores on the surgical ward compared with patient controlled analgesia.

Assessment of cytochrome P450 3A4 activity during the menstrual cycle using alfentanil as a noninvasive probe

BACKGROUND

Gender-dependent differences in cytochrome P450 activity, drug metabolism, drug elimination, and their clinical consequences are increasingly apparent. P450 3A4 is the most abundant P450 isoform in the human liver and is responsible for metabolizing a vast and diverse assortment of therapeutic agents, including opioids, benzodiazepines, and local anesthetics. P450, 3A4 activity is higher in women, influenced by steroid hormone levels, and is speculated to vary during the menstrual cycle. This investigation tested the hypothesis that P450 3A4 activity varies during the menstrual cycle. Alfentanil clearance was used as a metabolic probe for P450 3A4 activity.

METHODS

Alfentanil (20 micrograms/kg bolus) was administered to nine nonsmoking, nonpregnant female volunteers (age, 26 +/- 5 yr) with normal menstrual cycles on three separate occasions during the same menstrual cycle: days 2 (menstrual phase), 13 (estrogen peak), and 21 (progesterone peak). Venous plasma alfentanil concentrations were determined by gas chromatography-mass spectrometry. Alfentanil clearance was determined by noncompartmental methods and by a three-compartment model with both pooled population and two-stage analysis.

RESULTS

There was no significant difference in any measure of alfentanil clearance. Noncompartmental clearances (mean +/- SD) were 3.62 +/- 0.76, 3.81 +/- 0.96, and 3.60 +/- 0.84 ml/kg/ min, respectively, on days 2, 13, and 21 of the menstrual cycle.

CONCLUSIONS

Alfentanil clearances were not different on menstrual cycle days 2, 13, and 21, strongly suggesting no change in P450 3A4 activity. Menstrual cycle differences in alfentanil clearances do not contribute to interindividual variability in alfentanil disposition in women. If other P450 3A4 substrates are comparable, then menstrual cycle variability in their metabolism may not be a consideration in dosing or in the design of pharmacokinetic investigations.

Fibrinolytic responses to acute physical activity in older hypertensive men

We tested the hypothesis that the fibrinolytic response to acute physical activity is impaired in sedentary older hypertensive men, which may contribute to the risk of exertion-triggered acute myocardial infarction in this population. Tissue-type plasminogen activator (t-PA) antigen and activity and plasminogen activator inhibitor-1 (PAI-1) antigen and activity were measured in 12 hypertensive (69 +/- 1 yr) and 11 normotensive (64 +/- 1 yr) men before and after an acute bout of submaximal exercise. Contrary to our hypothesis, there were no differences between the two groups in the fibrinolytic response to exercise. t-PA antigen and activity were significantly elevated in both the hypertensive (38 and 172%, respectively) and normotensive (45 and 130%, respectively) groups immediately after exercise but they returned to resting levels within 30 min. There was no change in PAI-1 antigen levels immediately after exercise in either group; however, PAI-1 antigen was significantly lower at 30 and 60 min postexercise in both the hypertensive (31 and 16%, respectively) and normotensive (35 and 20%, respectively) groups. PAI-1 activity was significantly lower immediately after exercise in both the hypertensive (25%) and normotensive (22%) groups and remained lower than preexercise levels at 30 min (23 and 26%, respectively) and 60 min (16 and 12%, respectively) postexercise in both groups. The results of this study demonstrate that the fibrinolytic response to an acute bout of moderate physical activity is not impaired in sedentary older hypertensive men.

Limited utility of the phenylephrine-nitroprusside sigmoid curve method of measuring baroreflex function after myocardial infarction

BACKGROUND

Conventional testing of baroreflex function with phenylephrine bolus injection measures reflex vagal tone.

OBJECTIVE

To evaluate an alternative pharmacological method of baroreflex testing, which might provide more comprehensive evaluation of the baroreflex function in patients with uncomplicated myocardial infarction.

METHODS

Forty-eight patients, aged 59 +/- 7 years, were evaluated 5-7 days after myocardial infarction and after 6 weeks of rehabilitation. Baroreflex testing was performed with 10-14 incremental injections of nitroprusside and phenylephrine. The peak heart rate and blood pressure point from each injection were fitted to a four parameter (upper plateau, lower plateau, gain and median blood pressure) sigmoid logistic function. The baroreflex sensitivity (BRS) was also measured by conventional linear analysis of the response of the R-R interval to the initial rise in systolic blood pressure induced by phenylephrine bolus injection.

RESULTS

Non-linear curve fitting of four logistic curve parameters was possible for results from 91% of tests; in the remaining tests the upper plateau was held constant at the maximum heart-rate response to allow estimation of the other three parameters. When all four parameters had been estimated, the gain parameter could not be precisely determined (the coefficient of variation of the gain parameter was 85 +/- 10%). The upper (R = 0.72, P < 0.001) and lower plateaux (R = 0.76, P < 0.001) were strongly related to the resting heart rate and weakly related to measures of heart-rate variability. There was also a significant inverse correlation between the lower plateau and the BRS (R = -0.57, P < 0.001). The gain parameter was not related to the BRS or any measure of the heart-rate variability. After 6 weeks' rehabilitation there was a significant decrease in the lower plateau (from 54 +/- 2 to 48 +/- 1 beats/min, P < 0.001), an increase in BRS (from 9.4 +/- 0.8 to 12.1 +/- 0.8 ms/mmHg, P < 0.001) and no change in the other three sigmoid curve parameters.

CONCLUSIONS

Non-linear curve fitting of the heart-rate-blood-pressure relationship for patients after myocardial infarction is feasible but technical limitations and the lack of correlation between the gain parameter and other measures of autonomic function suggest that this method has limited usefulness. The lower plateau is related strongly to the BRS; both are vagal measures of cardiac autonomic function.

Defective fibrinolysis occurs after infrainguinal reconstruction

PURPOSE

Early thrombosis of infrainguinal bypass grafts may occur as a result of hypercoagulable states. Major surgical procedures are known to induce a procoagulant state that is manifested in part by reduced endogenous fibrinolytic activity or fibrinolytic shutdown. This study was performed to assess the timing and biologic mechanism of fibrinolytic shutdown after infrainguinal bypass procedures by direct assay of the serologic markers of in vivo fibrinolytic activity.

METHODS

Twenty patients underwent infrainguinal bypass procedures under epidural anesthesia. Endogenous fibrinolytic activity was assessed by measurement of tissue plasminogen activator (tPA) and its naturally occurring inhibitor, plasminogen activator inhibitor (PAI-1). The tPA and PAI-1 antigen (total protein) levels were determined using enzyme-linked immunosorbent assays, and measurements of in vivo biologic activity were performed using an amidolytic method. Measurements of tPA and PAI-1 were made before surgery, after surgery, and on postoperative days 1, 2, 7, and 30.

RESULTS

The mean preoperative PAI-1 activity was 20.6 +/- 1.4 arbitrary units (AU)/ml, which was higher than that of an age-matched population without severe atherosclerosis. PAI-1 activity rose significantly after surgery (29.6 +/- 2.2 AU/ml; p = 0.002) and remained elevated through the second day after surgery. Preoperative tPA activity level was 2.04 +/- 0.59 IU/ml and fell to 0.79 +/- 0.23 IU/ml (p = 0.046) immediately after the bypass procedure. All serologic indicators of fibrinolytic shutdown returned to baseline levels by 72 hours after surgery. No early graft thrombosis or other atherothrombotic complications occurred in these study patients.

CONCLUSIONS

Defective endogenous fibrinolytic activity occurs in the early postoperative period after infrainguinal bypass grafting procedures. Diminished endogenous fibrinolytic activity in these patients appears to be mediated by a combination of reduced tPA activity and significantly increased PAI-1 activity. No practical method is available to directly treat postoperative fibrinolytic shutdown, but postoperative antithrombotic therapy may be useful during this period to prevent early graft occlusion related to a relative hypercoagulable state.

Elevated germ cell markers in carcinoma of uncertain primary site do not predict response to platinum based chemotherapy

We carried out a retrospective review of the medical records of patients with metastatic carcinoma of unknown primary and either raised alpha fetoprotein (AFP) or beta human chorionic gonadotrophin (beta HCG) over a period of 6 years at three teaching hospital oncology units to assess response to platinum based chemotherapy. 15 patients were identified who fitted these criteria. Of these, 3 received no treatment because of poor functional status, 2 patients received only radiotherapy for symptomatic disease and died within 3 months of diagnosis and 1 patient died 2 weeks after diagnosis having received his first cycle of cisplatin-based chemotherapy. 9 patients received at least 2 cycles of chemotherapy. A complete tumour response was seen in only one patient who presented with midline lymphadenopathy and remains disease-free 46 months after treatment. This presentation was consistent with disease already known to herald platinum sensitivity. In the other 8 patients, there was only one partial response that lasted 2 months. The median survival for this group of 9 patients was 4.5 months (range 3 to > 46 months). Our data do not support the postulate that elevated germ cell markers in patients with carcinoma of unknown primary predict a response to cisplatin based chemotherapy.

Rapid development of hepatocellular siderosis after liver transplantation for neonatal hemochromatosis

A male infant with neonatal iron storage disease, also known as neonatal hemochromatosis (NH), underwent orthotopic liver transplantation (OLT) at the age of 55 days. The native liver contained an incidental hepatocellular carcinoma. Scant iron accumulation was found in a biopsy specimen of the implanted liver on the seventh postoperative day (POD); successive biopsies showed increasing siderosis. On POD 62, the patient died of a cardiac arrhythmia. Autopsy showed siderosis at many sites, including the implanted liver. We discuss the possibility that hemochromatosis recurred in the liver allograft and review possible factors contributing to the siderosis.

The effects of aging on the bone inductive activity of recombinant human bone morphogenetic protein-2

We examined the effects of gain on the ectopic bone-forming ability of recombinant human BMP-2 (rhBMP-2) in rats and investigated the mechanism by which aging might affect this type of bone. Bone formation induced after 12 days of sc implantation of 5 micrograms rhBMP-2 was reduced as animals aged from 1-16 months. The osteocalcin messenger RNA levels of implants also declined in aging animals. When the implant period was doubled, 16-month-old rats formed amounts of bone equivalent to those in 3-month-old rats. Increasing the dose of rhBMP-2 increased bone formation in older rats. To get a response comparable to that seen in 1-month-old rats given 5 micrograms rhBMP-2 for 12 days, 3-month-old rats required 30 micrograms rhBMP-2, whereas 16-month-old rats required 60 micrograms. Treatment with either GH or 1,25-dihydroxyvitamin D3 during the 12-day implantation period returned the bone formation in 16-month-olds rats to that in 3-month-old rats. These studies show that aging blunts rhBMP-2 inducted bone formation in rats. We speculate that the decreased response may be due in part to a decrease in the number of mesenchymal stem cells present in order rats or to a change in the responsiveness of these target cells to rhBMP-2.

GABAergic inputs to the nucleus rotundus (pulvinar inferior) of the pigeon (columba livia)

The avian nucleus rotundus, a nucleus that appears to be homologous to the inferior/ caudal pulvinar of mammals, is the major target of an ascending retino-tecto-thalamic pathway. Further clarification of the inputs to the rotundus and their functional properties will contribute to our understanding of the fundamental role of the ascending tectal inputs to the telencephalon in all vertebrates, including mammals. We found that the rotundus contains a massive plexus of glutamic acid decarboxylase (GAD)-immunoreactive axons using antibodies against GAD. The cells within the rotundus, however, were not immunoreactive for GAD. The retrograde tracer cholera toxin B fragment was injected into the rotundus to establish the location of the afferent neurons and determine the source of the gamma-aminobutyric acid (GABA) inputs into the rotundus. In addition to the recognized bilateral inputs from layer 13 of the tectum, we found intense retrograde labeling of neurons within the ipsilateral nuclei subpretectalis (SP), subpretectalis-caudalis (SPcd), interstitio-pretecto-subpretectalis (IPS), posteroventralis thalami (PV), and reticularis superior thalami (RS). All the neurons of the SP, SPcd, IPS, and PV were intensely GAD-immunoreactive. The neurons of layer 13 of the tectum were not immunoreactive for GAD. Following the destruction of the ipsilateral SP/IPS complex, we found a major reduction in the intensity of the GAD axonal immunoreactivity within the ipsilateral rotundus, but this destruction did not diminish the intensity of the GAD-immunoreactivity within the contralateral rotundus. Our studies indicated that the source of the massive GAD-immunoreactive plexus within the rotundus was from the ipsilateral SP, SPcd, IPS, and PV nuclei. These nuclei, in turn, received ipsilateral tectal input via collaterals of the neurons of layer 13 in the course of their projections upon the rotundus. We suggest that the direct bilateral tecto-rotundal projections are excitatory, whereas the indirect ipsilateral projections from the SP/IPS and PV are mainly inhibitory, possibly acting via a GABA-A receptor.

Recombinant human bone morphogenetic protein-2 induces a hematopoietic microenvironment in the rat that supports the growth of stem cells

In the mammalian bone marrow, stromal components support the growth and differentiation of blood cells. To study this complex system, we used a rat model in which ectopic hematopoietic tissue was induced to form after subcutaneous implantation of recombinant human bone morphogenetic protein (rhBMP-2). We showed that this organoid contained clonogenic precursors of both erythroid and myeloid lineages and progenitors competent to regenerate splenic lymphopoiesis. Furthermore, stem cells derived from ectopic foci conferred both short-term (30 day) and long-term (>6-month) protection in vivo against radiation-induced marrow aplasia. Lead shielding of the ectopic marrow in situ also permitted endogenous recovery of hematopoiesis after sublethal irradiation. Extending previous observations that most fibroblastoid cells of the marrow stain with the anti-ST3 antibody (but minimally with anti-ST4), whereas those growing from nonhematopoietic tissues react with anti-ST4, we found that analogous cells of the ectopic foci stained predominantly with anti-ST3. The ability to induce formation of a hematopoietic microenvironment from mesenchymal precursors may make possible the development of new strategies for the treatment of primary disorders of stem cells and irreversible stromal injury.

Ethical and practical problems of early anti-cancer drug trials: a review of the literature

Early clinical trials for new anti-cancer drug treatments typically use patients with cancer as research subjects. This paper identifies some of the ethical and practical concerns that arise from the recruitment of a vulnerable group of patients and their exposure to a drug of unknown risk or benefit. This review discusses the ethical principles related to recruitment and informed consent in cancer trials, and indicates that there is a lack of consensus concerning the requirements, process and practice of informed consent. It is suggested that, as yet, little is known about patients' decision making framework in this situation, and the need for further work that concentrates on the patient's point of view is highlighted. The paper concludes by discussing some of the difficulties associated with obtaining patients' opinions, and suggests that the use of a qualitative approach may overcome some of these problems.

Psychosocial aspects of participation in early anticancer drug trials. Report of a pilot study

Despite improvements in the treatment of many cancers, the need for effective new therapies is as great as ever. However, evaluating new drug treatments for cancer in clinical practice raises complex problems. Early trials of new drugs offer little in the way of therapeutic benefit, since their main aim is to identify toxic effects of the drug and subsequent doses for testing. The ethical and practical problems that these trials raise have received some attention in the literature. The main focus of previous studies has been the process of informed consent for trial participation, which has tended to reflect the perspective of the clinicians involved. Little attention has been given to patients' views in this context, and still less work has explored the total experience of clinical trial participation. In order to address these gaps in the literature, a research study was developed to explore the psychosocial aspects of participation in early anticancer drug trials from the perspective of the patient. This article reports the findings of a pilot study. The pilot study obtained the views of seven patients as they progressed through an anticancer drug trial. The informed consent process, the reasons behind decision-making concerning trial participation, and the impact of participation on the lives of the patients were explored, along with changing needs for information, care, and support as the trial progressed. Findings identify psychosocial aspects of clinical trial participation related to information, decision-making, and support from the perspective of those actually taking part.

The impact of outpatient drug services on abstinence among pregnant and parenting women

Although there is an increasing number of outpatient drug programs, there remains little consensus on which service components are most effective for pregnant and parenting women seeking treatment. In this investigation, we studied 48 women who remained in treatment for 5 consecutive months to: (1) examine differences between clients who maintained 30 to 90 days of abstinence and those who did not and (2) test the association between services and abstinence. Although we found no demographic differences between abstinent and nonabstinent women, we did find that significantly more abstinent women received family therapy services compared to nonabstinent women as they remained in treatment. Furthermore, we found that clients who were abstinent tended to receive more services overall than those who were not. Providers need to consider their population when deciding on which service components will be included: and family therapy is one service component that should be available to pregnant and parenting women.

The fibrinolytic system is not impaired in older men with hypertension

The fibrinolytic system is thought to be impaired in older hypertensive adults, thus contributing to the elevated risk of atherothrombosis, stroke, and acute myocardial infarction in this population. However, studies that have examined the fibrinolytic system in hypertensive individuals have failed to control for the confounding effects of other metabolic risk factors, making it difficult for one to determine the independent effect of hypertension on the fibrinolytic system. The purpose of the present study was to test the hypothesis that the fibrinolytic system is not impaired in older sedentary hypertensive men when the confounding effects of cardiovascular disease, diabetes, and dyslipidemia are controlled. Plasma concentrations of tissue-type plasminogen activator antigen and activity as well as plasminogen activator inhibitor-1 antigen and activity were measured under resting conditions in 12 hypertensive (69.4 +/- 1.4 years) and 11 normotensive 65.2 +/- 1.3 years) older men. The hypertensive and normotensive subjects had similar anthropometric and metabolic characteristics. There were no significant differences between the hypertensive and normotensive men in tissue-type plasminogen antigen (7.3 +/- 0.5 versus 6.1 +/- 0.6 ng/mL) and activity (1.8 +/- 0.3 versus 1.7 +/- 0.2 IU/mL) or plasminogen activator inhibitor-1 antigen (14.1 +/- 2.3 versus 10.8 +/- 2.2 ng/mL) and activity (17.4 +/- 1.2 versus 17.5 +/- 1.8 arbitrary units [AU]/mL) levels. In addition, the molar concentration ratio of active tissue type plasminogen activator to active plasminogen activator inhibitor-1 did not differ between the hypertensive (1:9.7 +/- 2.3) mmol/L) and normotensive (1:10.5 +/- 2.2 mmol/L) subjects, indicative of no impairment in fibrinolytic potential in either group. These results support the hypothesis that hypertension does not directly result in impaired fibrinolytic function in older adults. Furthermore, our findings suggest that abnormalities in fibrinolytic function in older hypertensive men are likely due to the primary effects of other metabolic disorders that usually accompany hypertension, such as hyperinsulinemia and dyslipidemia.

Self-administration of drugs on an oncology ward

This article focuses on the development of a programme of self-administration of medicines within an oncology setting. Previous studies which have developed this concept demonstrate that such a programme has a positive impact on a patient's knowledge of his/her illness and treatment. Compliance with drug regimens increases and patients are given back control over one aspect of their lives while in hospital. The development of an individualized drug administration programme within an oncology unit and how it will be evaluated in the future are described.

Teaching and learning clinical perception

A central task in clinical teaching is organization of the students' experience in clinical perception--the ability to observe, to recognize, to discriminate and to interpret clinical evidence. We cannot teach sensory perceptual experience. Students must experience the clinical phenomena for themselves. But we can ensure that what the student experiences is most likely to be turned into clinical learning. This paper dissects the learning task in order to derive plans for teaching clinical perception. A major purpose is to encourage closer study of physical examination, which has largely been upstaged by investigations. Students learn inductively from their experiences of examining patients, cumulating a 'clinical memory' of images of patients with diseases. Reflection on that experience with the clinical teacher translates the sensory evidence into words. Teachers link the clinical observations of 'disease in patients' with previously learned images of 'diseases in organs', to ensure that clinical features and underlying basic science knowledge are clearly integrated. Perception is an active process, not a passive reception of observational data. Learning and teaching clinical perception uses both the student's direct 'sense' experiences and the teacher's guidance in 'making sense' of them.

Centrifugal projections upon the retina: an anterograde tracing study in the pigeon (Columba livia)

Previous work has shown that the avian retina receives two types of centrifugal fibers from the brain. These types can be distinguished based on the size and the morphology of their terminal endings and have been termed convergent and divergent. The centrifugal fibers arise from the isthmooptic nucleus (ION) and the surrounding ectopic cell region (ECR). We used injections of anterograde tracers either to the ION/ECR or to the ECR only to determine the morphology, depth of termination, and regional distribution of the centrifugal fibers arising from each. We found that the ECR gives rise only to the divergent type of the centrifugal fiber, whereas the ION gives rise mainly to the convergent type but may also send some fibers of the divergent type. Most of the fibers project contralaterally, although a few from the ECR project ipsilaterally. The terminals of either type are not uniformly distributed throughout the retina; instead, they are found mainly in the inferior, midtemporal, to nasal portion of the retina and appear to avoid the fovea and most of the red field. By comparison, the ION receives a major projection from portions of the tectum that receive input from the fovea and the red field in a type of neural loop. The neural loop does not project to the same point (homotopic), but projects from the red field to the inferior retina (heterotopic), as was recently proposed by Holden (1990; Vis. Neurosci. 4:493-497). The distribution of centrifugal axons corresponds to displaced ganglion cells that selectively innervate the nuclei of the accessory optic system (AOS), including the nucleus of the basal optic root (dorsal, ventral, and lateral) and the nucleus lentiformis mesencephali, pars magnocellularis. We suggest that the centrifugal axons act by increasing the gain on the AOS, thereby enhancing retinal stabilization of gaze with improved accuracy of pecking of small objects.

Bicyclomycin and dihydrobicyclomycin inhibition kinetics of Escherichia coli rho-dependent transcription termination factor ATPase activity

The primary site of action for the novel antibiotic, bicyclomycin, in Escherichia coli has been identified to be the rho transcription termination factor. The inhibition of rho poly(C)-stimulated hydrolysis of ATP by bicyclomycin has been found to proceed by a non-competitive, reversible pathway with respect to ATP (Ki = 20 microM). Inhibition by dihydrobicyclomycin was similar (Ki = 75 microM). No change in the inhibitory properties of the antibiotic was observed under the assay conditions with the two rho mutants, Cys202Gly and Cys202Ser, indicating that Cys-202 does not affect drug binding to rho. Prolonged incubation (32 degrees C, 12 h) of wild-type rho with bicyclomycin (20 mM) led to protein degradation and a slow, permanent loss of rho ATPase activity after dialysis. Evidence was obtained that trace amounts of proteases present with bicyclomycin were responsible for the observed protein degradation. Treatment of wild-type and mutant rho proteins with purified bicyclomycin (25 mM) led to approximately 80% loss of ATPase activity after dialysis with no apparent loss of protein. However, a reduction of the electrophoretic mobility of the bicyclomycin-treated rho versus wild-type rho was seen. Addition of either ATP or poly(C) to wild-type rho led to partial protection against bicyclomycin inactivation, while inclusion of both ligands provided near complete protection against inactivation. The observed loss of ATPase activity upon prolonged incubation of rho with excess purified bicyclomycin is attributed to the covalent modification of the protein by the antibiotic at multiple sites.

A reassessment of ABO incompatibility in pediatric liver transplantation

The present study examined 144 pediatric liver transplants to determine the impact of ABO matching on liver allograft outcome. Pediatric transplants were divided into 3 groups: ABO identical (ABO-Id; n = 108), ABO-compatible nonidentical (ABO-Comp; n = 22), and ABO incompatible (ABO-Inc; n = 14). A higher proportion of United Network for Organ Sharing status 4 recipients in the ABO-Comp group (50% vs. 22% and 36% for ABO-Id and ABO-Inc, P < 0.05) and less time spent on the waiting list for ABO-Inc recipients (46 +/- 12 vs. 87 +/- 11 and 61 +/- 20 days for ABO-Id and ABO-Comp, P < 0.01) were noted. OKT3 induction therapy was greater in ABO-Inc grafts (57% vs. 19% and 14% for ABO-Id and ABO-Comp, P < 0.05), as was incidence of acute cellular rejection (79% vs. 59% and 41% for ABO-Id and ABO-Comp, P = 0.08). One- and 3-year patient survival rates were 87% and 83% in the ABO-Id group, 95% and 88% in the ABO-Comp group, and 79% and 79% in the ABO-Inc group (P = NS). One- and 3-year graft survival rates were 83% and 78% in the ABO-Id group, 87% and 80% in the ABO-Comp group, and 71% and 71% in the ABO-Inc group (P = NS). ABO-Inc transplantations can be performed successfully in pediatric recipients and warrant a reassessment of the utilization of ABO-Inc livers.

Intratelencephalic projections of the visual wulst in pigeons (Columba livia)

The visual wulst is the telencephalic target of the thalamofugal visual pathway of birds, and thus the avian equivalent of the striate cortex of mammals. The anterograde tracer Phaseolus vulgaris leucoagglutinin was used to follow the intratelencephalic connections of the major constituents of the visual wulst in pigeons. In particular, efferent pathways from the granular layer (Intercalated nucleus of the hyperstriatum accessorium, IHA), supragranular layer (hyperstriatum accessorium, HA), and infragranular layers (hyperstriatum intercalatus superior and/or hyperstriatum dorsale, HIS/HD) were investigated. These efferent projections were confirmed by injections of the retrograde tracer cholera toxin subunit B into their terminal fields. When a deposit of the anterograde tracer was centered in IHA, which receives the visual thalamic input, efferent fibers were seen mainly dorsomedially to IHA. When a deposit of the anterograde tracer was centered in HA, efferent fibers were seen to extend mainly in three directions: 1) medially to the tractus septomesencephalicus, which sends projections to extratelencephalic visual nuclei: 2) ventrolaterally to the lateral portion of the neostriatum frontale, where there were also labeled cells after the retrograde tracer was injected in HA; and 3) ventromedially to the paleostriatal complex, which is the avian equivalent of the mammalian caudale, 5) neostriatum intermedium, 6) archistriatum intermedium, and 7) hyperstriatum laterale. Finally, HIS/HD have projections predominantly to HA and the dorsocaudal telencephalon (area corticoidea dorsolateralis and area parahippocampalis), as well as relatively minor projections to the areas which also receive projections from HA. No anterogradely labeled fibers were seen in the tractus septomesencephalicus following the tracer injections in HIS/HD. These results indicate that the visual information from the granular layer is distributed via the supragranular layer HA to multiple areas within the telencephalon, such as the neostriatum frontale and paleostriatal complex. In addition, HA is the source of an extratelencephalic projection via the tractus septomesencephalicus. Thus, the avian supragranular layer HA contains neurons which are the source of both intratelencephalic and extratelencephalic projections, whereas neurons of the mammalian cortex are segregated into two distinct layers, supragranular and infragranular layers, based on the targets of their projections. The findings are further discussed and compared to the mammalian striate cortex.

Specificity of substance use in anxiety-disordered subjects

The current research (1) examines empirical evidence to substantiate the relationship between substance choice and chronology of onset of anxiety and substance use disorders, and (2) provides information on the specificity of substance choice among anxiety disorders. A study group of 181 subjects in the Harvard Anxiety Research Project (HARP) who had a history of substance use disorder were the focus of this examination. Subjects whose anxiety disorder had an onset before their substance use disorder (primary anxiety) were compared with those whose substance use preceded onset of an anxiety disorder (secondary anxiety) for differences in distribution of subjects among categories of substance of abuse. Primary and secondary anxiety groups do not have different ages of onset for substance use disorder, nor was there greater likelihood for choosing alcohol for any of the anxiety disorders. However, there is a decreased risk of alcohol use in the small group of generalized anxiety subjects and an increased risk of opioid use in the small group of posttraumatic stress disorder subjects. There was no indirect support for the self-medication hypothesis. Neither age of onset data, specific substance association, nor proximal diagnosis association support a simple interaction. The strongest finding supported an "avoidance" of CNS stimulants.

Clinical practice is not applied scientific method

Practice is often described as applied science, but real life is far too complex and interactive to be handled by analytical scientific methods. The limitations of usefulness of scientific method in clinical practice result from many factors. The complexity of the large number of ill-defined variables at many levels of the problem. Scientific method focuses on one variable at a time across a hundred identical animals to extract a single, generalizable 'proof' or piece of 'truth'. Clinical practice deals with a hundred variables at one time within one animal from among a clientele of non-identical animals in order to optimize a mix of outcomes intended to satisfy that particular animal's current needs and desires. Interdependence among the variables. Most factors in the illness, the disease, the patient and the setting are interdependent, and cannot be sufficiently isolated to allow their separate study. Practice as a human transaction involving at least two people is too complex to be analysed one factor at a time when the interaction stimulates unpredictable responses. Ambiguous data. Words have many usages. People not only assign different interpretations to the same words, they assign different 'meanings', especially according to the threat or hope they may imply. The perceptual data gleaned from physical examination may be difficult to specify exactly or to confirm objectively. The accuracy and precision of investigational data and their reporting can be low, and are frequently unknown. Differing goals between science and practice. Science strives for exact points of propositional knowledge, verifiable by logical argument using objective data and repetition of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)