Use of bioengineered human commensal gut bacteria-derived microvesicles for mucosal plague vaccine delivery and immunization

Plague caused by the Gram‐negative bacterium, Yersinia pestis, is still endemic in parts of the world today. Protection against pneumonic plague is essential to prevent the development and spread of epidemics. Despite this, there are currently no licensed plague vaccines in the western world. Here we describe the means of delivering biologically active plague vaccine antigens directly to mucosal sites of plague infection using highly stable microvesicles (outer membrane vesicles; OMVs) that are naturally produced by the abundant and harmless human commensal gut bacterium Bacteroides thetaiotaomicron (Bt). Bt was engineered to express major plague protective antigens in its OMVs, specifically Fraction 1 (F1) in the outer membrane and LcrV (V antigen) in the lumen, for targeted delivery to the gastrointestinal (GI) and respiratory tracts in a non‐human primate (NHP) host. Our key findings were that Bt OMVs stably expresses F1 and V plague antigens, particularly the V antigen, in the correct, immunogenic form. When delivered intranasally V‐OMVs elicited substantive and specific immune and antibody responses, both in the serum [immunoglobulin (Ig)G] and in the upper and lower respiratory tract (IgA); this included the generation of serum antibodies able to kill plague bacteria. Our results also showed that Bt OMV‐based vaccines had many desirable characteristics, including: biosafety and an absence of any adverse effects, pathology or gross alteration of resident microbial communities (microbiotas); high stability and thermo‐tolerance; needle‐free delivery; intrinsic adjuvanticity; the ability to stimulate both humoral and cell‐mediated immune responses; and targeting of primary sites of plague infection.

Long-Term Indwelling Silastic Central Venous Catheters: Clinical Audit Leading to Improved Surgical Technique

A retrospective audit of the surgical insertion and clinical outcome of silastic venous catheters on our Haematology Unit was performed for the period 1985 to 1988. Twenty-three (58%) of the 40 lines had complications, and analysis showed that many were due to problems related to the surgical technique used.

This altered our clinical practice, and over a 12 month period (January 1989 to January 1990) 26 central venous catheters have been placed in 24 patients by a dedicated surgical team using a standardized, altered technique. This has been to place all catheters via the right internal jugular vein and to confirm line position by on-table radiographic screening. A significant improvement in results is presented.

An aerosol challenge model of tuberculosis in Mauritian cynomolgus macaques

Background

New interventions for tuberculosis are urgently needed. Non-human primate (NHP) models provide the most relevant pre-clinical models of human disease and play a critical role in vaccine development. Models utilising Asian cynomolgus macaque populations are well established but the restricted genetic diversity of the Mauritian cynomolgus macaques may be of added value.

Methods

Mauritian cynomolgus macaques were exposed to a range of doses of M. tuberculosis delivered by aerosol, and the outcome was assessed using clinical, imaging and pathology-based measures.

Results

All macaques developed characteristic clinical signs and disease features of tuberculosis (TB). Disease burden and the ability to control disease were dependent on exposure dose. Mauritian cynomolgus macaques showed less variation in pulmonary disease burden and total gross pathology scores within exposure dose groups than either Indian rhesus macaques or Chinese cynomolgus macaques

Conclusions

The genetic homogeneity of Mauritian cynomolgus macaques makes them a potentially useful model of human tuberculosis.

Establishment of an aerosol challenge model of tuberculosis in rhesus macaques and an evaluation of endpoints for vaccine testing

The establishment of an aerosol challenge model in nonhuman primates (NHPs) for the testing of vaccines against Mycobacterium tuberculosis would assist the global effort to optimize novel vaccination strategies. The endpoints used in preclinical challenge studies to identify measures of disease burden need to be accurate and sensitive enough to distinguish subtle differences and benefits afforded by different tuberculosis (TB) vaccine regimens when group sizes are inevitably small. This study sought to assess clinical and nonclinical endpoints as potentially sensitive measures of disease burden in a challenge study with rhesus macaques by using a new protocol of aerosol administration of M. tuberculosis. Immunological and clinical readouts were assessed for utility in vaccine evaluation studies. This is the first example of TB vaccine evaluation with rhesus macaques where long-term survival was one of the primary endpoints. However, we found that in NHP vaccine efficacy studies with maximum group sizes of six animals, survival did not provide a valuable endpoint. Two approaches used in human clinical trials for the evaluation of the gamma interferon (IFN-gamma) response to vaccination (enzyme-linked immunospot [ELISpot] assay and enzyme-linked immunosorbent assay [ELISA]) were included in this study. The IFN-gamma profiles induced following vaccination were found not to correlate with protection, nor did the level of purified protein derivative (PPD)-specific proliferation. The only readout to reliably distinguish vaccinated and unvaccinated NHPs was the determination of lung lesion burden using magnetic resonance (MR) imaging combined with stereology at the end of the study. Therefore, the currently proposed key markers were not shown to correlate with protection, and only imaging offered a potentially reliable correlate.

Determination of lesion volume by MRI and stereology in a macaque model of tuberculosis

Sensitive and reproducible methods are needed to measure the impact on the host following experimental challenge with Mycobacterium tuberculosis, in order to determine the degree of protection conferred by new vaccines. Here we compare how well different clinical and post-mortem measures of disease burden predict the response by the host to increasing doses of M. tuberculosis in rhesus and cynomolgus macaques. The total lung and lesion volume was quantified from magnetic resonance imaging (MRI) digital stacks obtained from lungs of M. tuberculosis infected animals that were formalin fixed and scanned ex-vivo. The total lung lesion volume relative to the fixed whole lung volume was superior at indicating disease burden when compared to thoracic radiography, pathology scores, changes in body weight and temperature, as well as erythrocyte haemoglobin concentrations and sedimentation rate. The total lesion volume accurately reflected differences in challenge doses of M. tuberculosis that ranged from 30 to 500 CFU delivered by aerosol. The determination of total lesion volume from MR images demonstrated a species-dependent difference between rhesus and cynomolgus macaques in susceptibility to M. tuberculosis infection. MR stereology provides an accurate, quantifiable and relatively simple assessment, which can be easily standardized between laboratories and should form an essential component of the clinical assessment of disease progression, or vaccine efficacy.

Scrapie infection alters the distribution of plasma metabolites in diseased Cheviot sheep indicating a change in energy metabolism

Nuclear magnetic resonance (NMR) spectroscopy has been used to profile the metabolic status of plasma from; sheep showing clinical signs of scrapie, those known to be infected with scrapie but yet to show clinical signs, and control animals. The NMR measurements have shown that energy metabolism in scrapie infected animals is altered before the onset of clinical symptoms. These metabolic changes may provide the foundation for a pre-clinical diagnostic test for scrapie in sheep.

Comparative evaluation of the performance of two commercial kits for the detection of central nervous system tissue in meat

The ScheBo Brainostic test, which detects neuron-specific enolase by Western blotting, and the r-Biopharm Ridascreen Risk Material ELISA test, which detects the presence of glial fibrillary acidic protein, were evaluated using meats containing spinal cord and brain central nervous system (CNS) tissue from ovine and bovine species. The meats were pork, cooked pork sausage, raw minced lamb and cooked minced lamb. Spiking of the CNS tissue ranged from 0.01 to 5%. No false-positives were observed with either test using the manufacturers' analytical protocols. The presence or absence of CNS tissue was correctly determined in 20 of 20 samples using the ScheBo Brainostic test and 18 of 20 samples using the Ridascreen tests. When results were placed in categories according to quantity of CNS tissue detected, 19 of 20 samples were classified correctly using the Brainostic test and 14 of 20 samples using the Ridascreen test. Both kits were considered appropriate for reporting the presence of 1% or more CNS tissue in meat products, but the ScheBo Brainostic test was more consistent at detecting the presence of CNS tissues below the 1% level. Overall, the format of the Ridascreen test was technically easier to use, and the data simpler to interpret.

Survey of stable sulfur isotope ratios (34S/32S) of sulfite and sulfate in foods

A study was conducted to determine the natural abundance sulfur isotope ratios in foods containing sulphite preservatives. This involved determining (1) the accuracy and repeatability of sulfur isotope ratios measured using an elemental analyser (EA) coupled to an isotope ratio mass spectrometer (IRMS); and (2) the isotope ratios of 21 samples of commercially available S(IV) oxo-anion compounds, nine samples of S(VI) sulfate salts and the isotope ratios of the sulfate obtained by modified Monier-Williams distillation of SO(2) from 33 retail foods containing sulfite preservatives. The sulfur isotope ratio data for SO(2) recovered from foodstuffs showed a large spread of results, which suggested that the SO(2) derived from sulfite preservatives does not have a distinctive sulfur signature ratio. The range of results (3.1-52.1) overlapped with that found for a range of commercially available sulfite and sulfate reagents commonly used to preserve food (sulfites 2.5-13.7, sulfates 10.0-16.9). Whilst the variability in isotope ratios originated from the food samples themselves, evidence from the analysis of SO(2) gas suggested that isotope fractionation during dissolution, reaction and recovery was also a confounding factor.

Radiation exposure with use of the inverted-c-arm technique in upper-extremity surgery

BACKGROUND

Intraoperative fluoroscopy is commonly used in surgical procedures on upper extremities. We compared radiation exposure from two possible positions of the mobile digital fluoroscopy unit (c-arm): (1) the standard technique, with the x-ray tube down (near the floor) and the image intensifier at the top of the c-arm, and (2) the inverted position, in which the image intensifier is used as a table and the x-ray tube is up.

METHODS

A commercially available c-arm was used to irradiate a phantom hand in one of three configurations. In the first, the phantom hand was placed on an armboard equidistant from the x-ray tube and the image intensifier with the beam directed upward. In the second, the c-arm was inverted with the beam directed downward and the image intensifier used as a table. The third configuration was identical to the second except that a magnified image was used. Radiation exposure was measured at four locations corresponding to the approximate position of the surgeon's head, chest, and groin and the patient's hand.

RESULTS

The amount of radiation exposure to both the surgeon and the patient was significantly less when the c-arm was used in the inverted position (p < 0.0001). The dose rate to the patient's hand was reduced by 59%. The radiation exposure to the surgeon's head, body, and groin with the inverted-c-arm technique was 67%, 45%, and 15% of the measured doses with the x-ray-tube-down configuration. When we used the magnification mode of the image intensifier, with its correspondingly smaller field size, the doses were further reduced to 46%, 32%, and 11% of the standard-configuration values.

CONCLUSIONS

Use of the inverted-c-arm technique with the image intensifier as an operating table can significantly reduce radiation exposure to the surgeon and the patient during surgical procedures on upper extremities.

Methicillin-resistant Staphylococcus aureus infection in vascular surgical patients

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infection is emerging as a major problem in vascular surgical practice. The aim of this study was to review the management of patients with MRSA infection complicating vascular surgical operations.

METHODS

Data were obtained from the vascular audit, case notes, intensive therapy unit (ITU) notes, high dependency unit (HDU) notes and microbiological records of patients who underwent either arterial reconstruction (n = 464) or limb amputation (n = 110) between April 1994 and October 1998.

RESULTS

Forty-nine vascular surgical patients developed clinical MRSA infection (9%). Clinical MRSA infection in patients who had undergone aorto-iliac reconstruction (n = 18) was associated with a 56% mortality (n = 10) and the most common infections were bacteraemia (55%) and pneumonia (50%). MRSA infection occurred in 17 patients who had undergone infra-inguinal bypass and was associated with a 29% mortality (n = 5). The most common site of MRSA infection was the groin wound (76%) leading to anastomotic dehiscence and death in one patient (11%) and necessitating wound debridement in 4 patients (22%). MRSA infection of the groin wound in the presence of a prosthetic graft (n = 3) led to anastomotic dehiscence in 2 patients, and graft excision in 2 patients. Similar complications were not observed in the presence of an underlying autogeneous long saphenous vein graft (n = 16). MRSA infection following major lower limb amputation (n = 14) was associated with death in 5 patients (36%). Wound infection in 10 amputees (71%) led to revision of the amputation to a higher level in 2 (14%) and wound debridement in 2 (14%).

CONCLUSIONS

MRSA infection has a high mortality in vascular surgical patients in general, and following aorto-iliac reconstruction in particular. Autogeneous vein may confer some protection against local complications following groin wound infection. Strategies aimed at reducing the incidence of infection, including strict adherence to infection control procedures, may reduce the severity of this problem.

Primacy in causal strength judgments: the effect of initial evidence for generative versus inhibitory relationships

The order in which people receive information has a substantial effect on subsequent judgment and inference. Our focus is on the order of covariation evidence in causal learning. The first experiment shows that the initial presentation of evidence suggesting a generative causal relationship (the joint presence or joint absence of cause and effect) leads to higher judged causal strength than does the initial presentation of evidence suggesting an inhibitory relationship (the presence of cause or effect in the absence of the other). Additional studies show that this primacy effect is unlikely to be due to fatigue or to an insufficient number of learning trials. These results are not readily explained by current contingency-based or associative theories of causal induction.

Causal status as a determinant of feature centrality

One of the major problems in categorization research is the lack of systematic ways of constraining feature weights. We propose one method of operationalizing feature centrality, a causal status hypothesis which states that a cause feature is judged to be more central than its effect feature in categorization. In Experiment 1, participants learned a novel category with three characteristic features that were causally related into a single causal chain and judged the likelihood that new objects belong to the category. Likelihood ratings for items missing the most fundamental cause were lower than those for items missing the intermediate cause, which in turn were lower than those for items missing the terminal effect. The causal status effect was also obtained in goodness-of-exemplar judgments (Experiment 2) and in free-sorting tasks (Experiment 3), but it was weaker in similarity judgments than in categorization judgments (Experiment 4). Experiment 5 shows that the size of the causal status effect is moderated by plausibility of causal relations, and Experiment 6 shows that effect features can be useful in retrieving information about unknown causes. We discuss the scope of the causal status effect and its implications for categorization research.

Plethysmography: the new wave in haemodynamic monitoring--a review of clinical applications

The plethysmograph, a useful, non-invasive circulatory assessment capability featured on most modern pulse oximeters, provides a waveform representation of pulsatile peripheral blood flow, from which can be drawn assessments of both the peripheral and central circulation. Implementation and maintenance of plethysmography monitoring is straightforward and uncomplicated by virtue of its non-invasiveness. Yet despite its capabilities, ease of use and widespread availability it remains an underutilised data source. Diagnostic and monitoring capabilities of the device include heart rate and rhythm monitoring, detection of myocardial and valvular dysfunction, assessment of intra-aortic balloon pump performance when pressure waveforms are unobtainable, detection and measurement of pulsus paradoxus, improved performance of the Allen's test and detection of peripheral vascular diseases, peripheral vasoconstriction and developing shock. This paper describes the range of established applications of plethysmography, reviews pertinent literature and describes the directions in which, in the absence of supportive literature, clinical practice is finding applications.

Determination of the oxygen-18/oxygen-16 isotope ratios of sugar, citric acid and water from single strength orange juice

The ratio of the stable isotopes of oxygen (18O/16O) has been measured in the sugar, citric acid and water from authentic single strength orange juices, originating from a number of different countries. The sugars and citric acid were recovered from the juices and their 18O/16O ratios were determined by pyrolysis/continuous flow-isotope ratio mass spectrometry (Py/CF-IRMS). The 18O/16O ratio of the fruit juice water was determined by the carbon dioxide/water equilibration method. The delta 18O/1000 values of 45 different sugars ranged from +29.1 to +38.8/1000 and 15 citric acids ranged from +18.9 to +25.4/1000. The delta 18O/1000 value of the water present in the same samples ranged from -2.1 to +7.8/1000. A correlation was evident between the delta 18O/1000 values of the sugar, citric acid and water from the juices. This information can be used to improve the assessment of the authenticity of commercial 'freshly squeezed' orange juices. The detection of the presence of reconstituted orange juice concentrate in 'freshly squeezed' orange juices was improved by 37% using regression analysis of the combined water and sugar delta 18O/1000 ratios when compared to the use of delta 18O/1000 ratios of fruit juice water alone.

Developmental toxicity and toxicokinetics of two endothelin receptor antagonists in rats and rabbits

Embryo-fetal development studies with toxicokinetic evaluations were conducted in rats and rabbits after oral or intravenous administration of two endothelin receptor antagonists. In the rat studies, females were administered SB-217242 (0.01-300 mg/kg/day) orally or SB-209670 (0.01-50 mg/kg/day) intravenously from days 6-17 postcoitus (pc). External and visceral fetal examinations were performed at necropsy on day 21 pc. Maternal body weight and food consumption were decreased only at 300 mg/kg/day SB-217242. Embryolethality was seen at 300 mg/kg/day SB-217242. Decreased fetal body weight occurred at 300 mg/kg/day SB-217242 and 50 mg/kg/day SB-209670. Dose-dependent increases in the mean percentage of fetuses per litter with malformations were seen at > or = 50 mg/kg/day SB-217242 and > or = 10 mg/kg/day SB-209670. Craniofacial, great vessel, heart, and thyroid were the predominant malformations. In the rabbit studies, females were administered SB-217242 (0.01-50 mg/kg/day) orally or SB-209670 (0.01-25 mg/kg/day) intravenously from days 6-20 pc. There was no drug-related effect on maternal body weight or food consumption. Embryolethality was observed at 50 mg/kg/day of SB-217242. Dose-related increases in the mean percentage of fetuses per litter with malformations were seen at > or = 10 mg/kg/day SB-217242 and > or = 10 mg/kg/day SB-209670. The malformations were similar to those observed in the rat studies, except that craniofacial development was not altered by SB-209670. The malformations observed are consistent with the pattern of endothelin-1 gene expression described in mouse embryonic pharyngeal arches and heart, and with the craniofacial and cardiovascular malformations observed in endothelin-1-deficient mice. Given the known role for endothelins in development, and concordant malformations in rats and rabbits observed in this study, teratogenicity is likely to be a class effect of endothelin receptor antagonists.

The role of screening blood tests in patients with arterial disease attending vascular outpatients

OBJECTIVE

To evaluate the benefits of a policy of performing screening blood tests in new patients with arterial disease referred to the vascular outpatients department.

METHODS

Clinical audit over a 12-month period of all new referrals with arterial disease to the vascular outpatients department at the Leicester General Hospital.

RESULTS

Two hundred and seventy-two patients had at least one blood test performed at their outpatient visit. All of these patients had a full blood count performed, of which 21 results (21%) were abnormal. Further investigation of patients with abnormal results revealed one case of bladder cancer, one case of leukaemia and one patient with polycythaemia. Urea and electrolytes were measured in 269 patients (99%). Of these, 26 (10%) were expectedly abnormal in patients with known renal impairment. A further 27 patients (10%) were identified to have some degree of unrecognised renal impairment. Serum non-fasting glucose was measured in 252 patients (93%). There were 11 unexpectedly raised results, but further investigation of these patients only diagnosed one of these patients as diabetic. Serum cholesterol was measured in 201 patients (74%). One hundred and thirty-two patients (66%) had an abnormally raised serum cholesterol level. Of these, only 12 patients (6%) were known to have hyperlipidaemia.

CONCLUSIONS

Screening new patients with arterial disease in vascular outpatients does identify significant abnormalities, in particular renal impairment and hyperlipidaemia. Correction of these abnormalities may reduce the morbidity associated with contrast induced nephrotoxic acute renal failure, and also contribute to secondary prevention of vascular events associated with raised lipids.

Enhancement of Xe-133 ventilation lung scan image acquired after Tc-99m perfusion scan

In nuclear medicine, the match and mismatch between the images of lung perfusion and ventilation provide an important criterion to diagnose pulmonary embolism. Usually, for imaging clarity, the ventilation scan using 133Xe is performed before the perfusion scan using 99mTc. But the inverse order is preferred clinically, since (i) if the perfusion image is normal, there is no need to do the ventilation scan, and (ii) if the perfusion image is abnormal, the ventilation image can be obtained by focusing on the perfusion abnormalities. However, the quality of the ventilation image is reduced if the ventilation scan is performed after the perfusion scan, because the 140 keV photons emitted from 99mTc will scatter into the acquisition window of 133Xe (81 keV). The purpose of this study is to apply image processing techniques to reduce the scattering effect of 99mTc to get a better 133Xe ventilation image. First, an image sequence in the preferred inverse order is simulated using the images acquired in the normal order. Image processing techniques are used to find an optimized way to reduce the scattering background in the ventilation image. Second, a real image sequence is acquired in the inverse order. An improved ventilation image is then obtained by applying image processing techniques to this image sequence.

Computer analysis of human depth EEG in different sleep stages

This study compares delta (< 4 Hz), theta (4-8 Hz), alpha (8-12 Hz) and beta (12-20 Hz) band EEG signals during wakefulness, rapid-eye-movement (REM) sleep, and stage 1 and stage 2 non-REM sleep recorded from both surface and depth electrodes in patients with drug-resistant partial seizures. Computer analysis utilizing Fast Fourier Transforms (FFT) was performed with the Neurovision software developed for this purpose. Mean amplitudes were calculated for each of the frequency bands. Preliminary analysis was performed with emphasis on the presence and characteristics of theta activity in the hippocampus of the brain. Results demonstrate theta wave activity in the hippocampus with an increase of theta activity in REM sleep as compared to non-REM sleep (stages 1 and 2).

Arterial thrombosis: a complication of loop ileostomy

Restorative proctocolectomy has become the surgical treatment of choice in ulcerative colitis. Most commonly, this is performed as a staged procedure which includes formation of a defunctioning loop ileostomy. High output loop ileostomies are associated with both local and systemic complications. We describe two patients with loop ileostomies who developed acute arterial thrombosis, a complication not previously described, thus further emphasizing the importance of careful management and early reversal of high output ileostomies.

In vivo resistance to simian immunodeficiency virus superinfection depends on attenuated virus dose

Infection of macaques with attenuated simian immunodeficiency virus (SIV) induces potent superinfection resistance that may be applicable to the development of an AIDS vaccine but little information exists concerning the conditions necessary for the induction of this vaccine effect. We report that only a high dose of attenuated SIVmac protected macaques against intravenous challenge with more virulent virus 15 weeks after primary infection. Three of four animals given 2000-20000 TCID50 of SIVmacC8, a molecular clone of SIVmac251(32H) with a 12 bp deletion in the nef gene, essentially resisted superinfection with uncloned SIVmac. In two animals challenge virus was never detected by PCR and in one animal challenge virus was detected on one occasion only. Although animals given 2-200 TCID50 of attenuated virus were superinfected they were spared from the loss of CD4 cells seen in infected naive controls. Protection from superinfection did not correlate with immune responses, including the levels of virus-specific antibodies or virus-neutralizing activity measured on the day of challenge; although, after superinfection challenge, Nef-specific CTL responses were detected only in animals infected with high doses of attenuated SIV. Unexpectedly, cell-associated virus loads 2 weeks after inoculation were significantly lower in animals infected with a high dose of attenuated SIV compared to those in animals infected with a low dose. Our results suggest that the early dynamics of infection with attenuated virus influence superinfection resistance.

Acute arterial thrombosis after a long-haul flight

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The pharmacokinetics of topotecan and its carboxylate form following separate intravenous administration to the dog

PURPOSE

To determine the relationship between topotecan and its ring opened hydrolysis product (SK&F 105,992) following intravenous administration of the two agents separately, and to determine the bio-availability of topotecan in female beagle dogs.

METHODS

The pharmacokinetics of topotecan and SK&F 105,992 were determined following separate administration as 30 minute intravenous infusions in a cross-over design. Topotecan was also administered orally to the same dogs.

RESULTS

When administered intravenously to dogs, SK&F 105,992 underwent interconversion to topotecan. Plasma concentrations of both topotecan and SK&F 105,992 appeared to decline multi-exponentially following i.v. infusion of either compound. A 2-compartment model was found to adequately characterize the data.

CONCLUSIONS

The clearance of topotecan by other routes proceeded at a faster rate than its interconversion to SK&F 105,992, whereas the clearance of SK&F 105,992 by other routes was slower than the rate of its interconversion to topotecan. Any SK&F 105,992 formed in the GI tract did not appear to be well absorbed following oral administration of topotecan to dogs. The steady-state volume of distribution for topotecan was approximately 8- to 9-fold greater than that for SK&F 105,992 in the dog. After intravenous administration of topotecan, the amount of topotecan in the dog was much greater than that of the carboxylate, even though their respective plasma concentrations were similar. The bioavailability of topotecan, calculated from oral topotecan data or from SK&F 105,992 data, was approximately 50%.

Evening dosing is associated with higher plasma concentrations of pranlukast, a leukotriene receptor antagonist, in healthy male volunteers

AIMS

To study the magnitude of differences in the pharmacokinetics of pranlukast, after morning and evening administration.

METHODS

Pranlukast (300 mg) was administered to 12 healthy male volunteers on two separate occasions, either in the morning or evening. Both doses were given 30 min after a standard high fat content meal. Blood samples were collected up to 18 h postdose. Plasma was assayed by high performance liquid chromatography. Standard pharmacokinetic and statistical analyses were performed.

RESULTS

Statistically significant (P < 0.05) increases were noted in AUC(o,t) (56%) and tmax (2.5 h) after evening administration. Cmax was 14% higher after evening dosing (95% C.I. 0.71-1.84).

CONCLUSIONS

Pranlukast bioavailability is apparently increased after evening dosing as compared with morning administration. Higher night-time and early morning plasma concentrations may confer additional therapeutic benefit at a time when asthmatics are at greatest risk of developing bronchospasm.

Regulation of mitogenesis by kinins in arterial smooth muscle cells

Recent evidence suggests that bradykinin (BK) plays a role in regulating neointimal formation after vascular injury. The present study examined the mechanism whereby BK regulates platelet-derived growth factor (PDGF) AB-induced mitogenesis in smooth muscle cells from rat mesenteric artery. BK, but not other activators of phosphoinositidase C (e.g., angiotensin II), inhibited PDGF-stimulated mitogenesis. The B1 receptor agonist des-Arg9-BK (DABK) was more potent than the B2 agonist BK; smaller BK fragments had no activity. In studies in which the B2 receptor antagonist HOE-140 {D-Arg0[Hyp3,beta-(2-thienyl)-Ala5,D-Tic7,Oic 8]BK} and the B1 receptor antagonist DHOE [[D-Arg0,Hyp3,beta-(2-thienyl)-Ala5,D-Tic7,Oi c8,des-Arg9]BK] were used, both receptors independently mediated inhibition of PDGF-induced mitogenesis. There was no evidence for metabolism of BK to DABK. The rank potency for activating phosphoinositidase C and increasing intracellular Ca2+ (BK > DABK) was opposite that for inhibiting mitogenesis (DABK > BK). Inhibition of cyclooxygenase did not prevent the kinin-mediated inhibition. Kinetic analysis of the cell cycle effects of kinins on PDGF-stimulated mitogenesis revealed that continuous exposure to DABK or BK was inhibitory even when added shortly before the cells initiated DNA synthesis (S phase). However, short-term exposure (5-60 min) to DABK or BK was inhibitory only when added after exposure to PDGF. These data suggest that the B1 and B2 receptors potently inhibited PDGF-stimulated mitogenesis and proliferation by activating an alternative signal transduction cascade not involving phosphoinositidase C or prostaglandins. The inhibition occurred at a point late in progression of the cell cycle from G1 to S and was dependent on the presence of kinins after exposure to PDGF.

Macaques infected with live attenuated SIVmac are protected against superinfection via the rectal mucosa

Good protection against systemic challenge in the SIVmac model of AIDS has been provided by prior infection with attenuated virus. To determine if such protection extends to intrarectal mucosal challenge two molecular clones, SIVmacC8 and SIVmacJ5, were used in this study. SIVmacC8 has an attenuated phenotype in vivo, due to a 12-bp deletion in the nef/ 3'-LTR, whereas SIVmacJ5 has a full size nef open reading frame and induces AIDS in infected macaques. The J5 molecular clone was shown to infect rhesus macaques following atraumatic intrarectal inoculation. The dynamics were similar to those following intravenous inoculation resulting in early, high, cell-associated viremia and seroconversion. Four macaques previously infected with the attenuated SIVmacC8 resisted superinfection with SIVmacJ5, following intrarectal inoculation. These animals also resisted intrarectal infection with an HIV/SIV chimeric virus (SHIV) composed of SIVmac239 expressing the HXBc2 env, tat, and rev genes, suggesting that immunity to the envelope proteins was unlikely to be involved in the superinfection resistance. Infection with the attenuated SIVmac generated cytotoxic T lymphocytes (CTL) detectable in the peripheral circulation, serum neutralizing antibodies, and SIV-binding antibodies in rectal fluids. SIVmacC8 proviral DNA was found in lymph nodes removed at necropsy but there was no evidence for local sequestration of challenge virus. SIV-specific CTL, were detected in gut-associated lymph nodes and may have a role in limiting superinfection following mucosal exposure.

An overview of the clinical pharmacology of topotecan

Topotecan (Hycamtin; SmithKline Beecham Pharmaceuticals, Philadelphia, PA), a topoisomerase I inhibitor, is a semisynthetic camptothecin that has been structurally modified for increased water solubility. The closed lactone ring predominates at acidic pH, but the reverse reaction of the parent into the metabolite predominates at physiologic pH. The pharmacokinetic profile of topotecan is usually characterized by a two-compartment model and is linear in the dose range of 0.5 to 3.5 mg/m2. Following intravenous administration for 5 days at doses of 0.5 to 1.5 mg/m2/d as a 30-minute infusion, topotecan has a volume of distribution of approximately 130 L. Mean plasma clearance for topotecan (total) was approximately 1,000 mL/min with a plasma half-life of 2 to 3 hours. Renal clearance is an important determinant of topotecan elimination, with approximately 30% of the dose excreted in the urine. In three phase I studies in which the schedule of five daily doses every 21 or 28 days was investigated, all found 1.5 mg/m2/d to be the maximum tolerated dose. Neutropenia (reversible and noncumulative over time) was the major dose-limiting toxicity; fevers and infections were infrequently reported. The magnitude of topotecan exposure was correlated to the observed myelosuppression.

The contribution of azodicarbonamide to ethyl carbamate formation in bread and beer

Data on ethyl carbamate concentrations in beers purchased and analysed between 1988 and 1990 are presented. The concentrations in draught beers were uniformly below the detection limit of 1 microgram/l. Canned beers contained rather more ethyl carbamate (up to 2.5 micrograms/l) which is considered to be due to their longer shelf-life and higher alcohol content (in some cases). Bottled beers contained even higher amounts of ethyl carbamate (up to 14.7 micrograms/l) and this was considered to be due to the use of azodicarbonamide as a blowing agent in the beer bottle cap liners. It is understood that modifications to the liner have led to reduced concentrations in bottled beers produced more recently. A survey of bread samples and related cereal products such as rusks, French toasts and pitta bread indicated typical ethyl carbamate concentrations between < 0.4 and 4.5 micrograms/kg. Toasting bread led to increases of between three- and eight-fold in ethyl carbamate concentrations ranging from 3.5 to 33.8 micrograms/kg on a wet weight basis. Analysis of the data indicated that commercial bread samples which indicated the use of azodicarbonamide as a flour improver showed statistically significant increases in ethyl carbamate concentrations. The mean increase for treated bread over untreated bread was 66%. When these breads were toasted, the mean increase for treated toast over untreated toast was 56%.

The effect of azodicarbonamide concentrations on ethyl carbamate concentrations in bread and toast

A series of baking experiments have been undertaken in order to test the proposition that the use of the flour improver azodicarbonamide influences ethyl carbamate concentrations in baked bread. Samples were prepared in a laboratory and contained 0, 20 and 45 mg azodicarbonamide/kg; 20 mg/kg reflecting normal commercial usage and 45 mg/kg the UK statutory limit. Samples incorporating 0 and 20 mg/kg of the additive were also prepared in a commercial bakery. Toast made from these breads was examined since it is known that toasting can lead to increased ethyl carbamate concentrations. Statistical analysis of the data indicated that, at 45 mg/kg, azodicarbonamide led to significant increases in ethyl carbamate concentrations in both bread and the toasts made from it. At 20 mg/kg some small increases in ethyl carbamate were seen for bread and this approached statistical significance for those samples made in the commercial plant. When these breads were toasted an increase in ethyl carbamate was observed but this was not attributable to the use of azodicarbonamide.

Must living renal donors be hospitalized overnight prior to surgery?

To determine whether preoperative intravenous hydration was an important determinant of perioperative safety for the kidney donor or of early allograft function, 21 consecutive living donor transplants were assessed retrospectively. Donors hospitalized overnight received 1008 +/- 169 mL of intravenous fluid during the 8 h prior to operation, compared to no preoperative hydration among a cohort of 15 patients. No differences between intraoperative blood pressures, fluid administration, urine output, or time in the operating room were identified between groups. Postoperative allograft function was not compromised by the lack of hydration. We conclude that living kidney donors can safely undergo elective nephrectomy without prior intravenous hydration.

The pharmacokinetics of pranlukast in healthy young and elderly subjects

Pranlukast is a novel LTD4 antagonist under development for the treatment of asthma. To assess the effect of age, the pharmacokinetics of pranlukast were studied in healthy young (9 females, 10 males, mean 30 years) and elderly subjects (9 per sex, mean 70.4 years). After an overnight fast volunteers were given 300 mg of pranlukast orally, 30 min after a light breakfast. Serial blood samples were collected for 24 hs, and the plasma was assayed by HPLC/UV. Pranlukast was well tolerated by the volunteers. The resultant mean plasma concentration vs. time data were very similar for both age groups. The estimated geometric mean AUCO-t and Cmax ratios (95% CI in parentheses) for elderly : young were 1.00 (0.71, 1.41) and 0.93 (0.66, 1.33), respectively. Median Tmax occurred at 4.5 h in both age groups. There were no significant differences observed in the pharmacokinetics of pranlukast between healthy young and elderly subjects. On stratifying the young and elderly data with respect to gender, no marked differences were observed between male and female subjects in the mean pharmacokinetic parameters of pranlukast, and the respective plasma concentrations profiles were very similar.

The bradykinin B2 receptor is a delayed early response gene for platelet-derived growth factor in arterial smooth muscle cells

Bradykinin and platelet-derived growth factor (PDGF) are inflammatory mediators important in the response to vascular injury. Based upon the known effect of oncogenic Ras to increase bradykinin receptor expression and the ability of PDGF to stimulate Ras, we examined whether PDGF regulates bradykinin B2 receptor expression in cultured arterial smooth muscle cells. Treatment with PDGF (AB and BB, but not AA) produced a dose- and time-dependent increase in both mRNA (6-7-fold increase at 2-4 h) and cell surface receptors (2-4-fold at 6-12 h) for the B2 receptor. There was a 60-min delay between exposure to PDGF and the initial increase in B2 receptor mRNA. Transcriptional inhibitors, actinomycin D or 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole, completely blocked the increase in B2 receptor mRNA when added up to 60 min after stimulation with PDGF. However, protein synthesis was not required, as treatment with cycloheximide did not block but rather superinduced the PDGF-induced increase in B2 receptor mRNA. Comparison with the immediate early response gene c-fos demonstrated that the increase in B2 receptor mRNA was similarly inhibited by the tyrosine kinase inhibitor, tyrphostin, as well as staurosporine. However, stimulation of c-fos was slightly more sensitive to genistein, while the B2 receptor mRNA was more sensitive to inhibition by the protein kinase C inhibitor, calphostin C. The increase in cell surface B2 receptors were functionally coupled to an increase in phosphoinositide-specific phospholipase C, and the effects of PDGF were selective as there was no increase in either angiotensin II- or arginine vasopressin-induced inositol phosphate formation or intracellular calcium release. Taken together, these results demonstrate that the B2 receptor is a delayed early response gene for PDGF in vascular smooth muscle cells.

The single and multiple dose pharmacokinetics of pranlukast in healthy volunteers

OBJECTIVE

The pharmacokinetics of pranlukast, a leukotriene LTD4 antagonist, were studied in 48 young, healthy subjects after single and repeated oral doses (given every 12 h) ranging from 112.5 to 675 mg. The doses were administered 30 minutes after a light breakfast.

RESULTS

Maximal drug concentrations generally occurred between 2 and 6 h after dosing, and there was some evidence of an absorption lag-time. Secondary peaks were observed in the plasma concentration vs. time profiles of many of the study subjects after both single and repeated doses, particularly during the period of maximum drug absorption. In general, after both single and repeated doses, there were related increases in the corresponding Cmax and AUC with a rise in dose, although the increase was diminished at doses above 450 mg. With repeated dosing of pranlukast the mean AUC was generally higher (up to 1.6-fold), and the higher plasma concentrations allowed characterisation of a longer mean t 1/2 than after single dose administration. The mean steady-state trough plasma concentrations attained after evening doses were considerably higher (up to 14-fold) than those obtained after the morning dose.

CONCLUSION

The data suggested that the pharmacokinetics of pranlukast are influenced by the time of dosing. Based on analysis of urinary 6 beta-hydroxycortisol excretion, there was no evidence that pranlukast modified the metabolic activity of cytochrome P-450 3A isoenzymes.

Constitutive expression of major histocompatibility complex class II antigens on monocytes and B cells correlates with disease in simian immunodeficiency virus-infected rhesus macaques

Constitutive host factors that influence progression to AIDS are understood poorly. In the macaque model for AIDS, 35 animals infected with simian immunodeficiency virus (SIV) were analyzed for major histocompatibility complex class II antigen expression on blood monocytes and B cells by immunostaining and flow cytometry. Expression varied widely between animals but was constant with time. Level of expression and the proportion of monocytes and B cells that expressed class II were not affected by SIV infection. Significantly more animals developed AIDS in the group with low class II expression than in the group with high expression (P < .001). Progression to disease was faster in animals that expressed poorly (P < .01), and opportunistic pathogens were more common (P < .05). Thus, the constitutive level of class II antigen expression may be a useful prognostic indicator for human immunodeficiency virus disease in humans and may be an important factor in the design of vaccine trials.

Simulation of the upper gastrointestinal fluoroscopic examination for calculation of absorbed dose in tissue

In order to simulate the upper gastrointestinal fluoroscopic examination, modifications were made to the Monte Carlo radiation-transport code that uses the anthropomorphic, mathematical reference phantoms ADAM and EVA. A set of discrete x-ray field projections of the principal anatomy of clinical interest has been previously defined. This note describes the new features incorporated in the simulations--divergent beams in oblique irradiation geometries, an esophagus and a duodenum, a double contrast medium consisting of a BaSO4-H2O mixture and air in the esophagus, stomach, and duodenum, and clinically representative beam qualities. The absorbed doses in tissues per unit entrance exposure (free-in-air) computed with the modified code appeared in Department of Health and Human Services Publication FDA 92-8282, Handbook of Selected Tissue Doses for the Upper Gastrointestinal Fluoroscopic Examination. A minor correction is described for the previously reported results for the esophagus.

A liquid chromatographic assay for the stereospecific quantitative analysis of halofantrine in human plasma

A stereospecific liquid chromatographic (LC) assay was developed for the quantification of the antimalarial drug, halofantrine, in human plasma. Following protein precipitation with acetonitrile, the enantiomers of halofantrine were extracted from human plasma using ammonium hydroxide and tert-butyl methyl ether-hexane. A precolumn derivatization step was employed using (+)-di-O-acetyl-L-tartaric acid anhydride to form diastereomeric derivatives of the halofantrine enantiomers. Chromatographic resolution of the diastereomers was performed using reversed-phase LC with UV detection at 254 nm. The recovery of (+/-)-halofantrine from human plasma at 25 and 2000 ng ml-1 was 68.2 and 61.4%, respectively. The derivatization yield following extraction and derivatization of 2000 ng ml-1 of (+/-)-halofantrine was 95.6%. Using 0.5 ml of plasma, the limit of quantification for each halofantrine enantiomer was 12.5 ng ml-1. Linear responses in analyte/internal standard peak height ratios were observed for analyte concentrations ranging from 12.5 to 1000 ng ml-1. Chromatograms of drug-free plasma showed no interfering peaks with retention times similar to those for (+)- and (-)-halofantrine or internal standard. Based on the validation data, the assay performed well over the enantiomer concentration range of 12.5-500 ng ml-1.

Case report: intestinal perforation--an unusual complication of endoscopic biliary stenting

The endoscopic placement of stents to decompress biliary obstruction is accepted practice in the management of malignant biliary strictures. In our patient, a 73-year-old man with a presumed malignant common hepatic duct stricture, palliation of his obstructive jaundice has been achieved. However, his clinical course was complicated by a colonic perforation--a previously unreported complication of distal stent migration.

The determination of the flour improver potassium bromate in bread by gas chromatographic and ICP-MS methods

The development and application of two methods for determining bromate in bread are described. A gas chromatographic (GC) method which relied on the formation of a volatile derivative of bromate gave a detection limit of 12 micrograms/kg. Duplicate analyses agreed well but recovery from breads spiked with bromate were low and averaged 30% for brown bread and 42% for white bread. Further studies indicated that this was caused by the derivatization reaction being suppressed by components of the sample and reagents used in their preparation. After taking both these factors into account, a recovery of 80% could be achieved. The GC method was used to carry out a survey of retail bread samples in 1989. Bromate was found in all six unwrapped breads analysed (median 35 micrograms/kg, range 17-317 micrograms/kg), whilst for 22 wrapped breads, seven were found to contain bromate (median < 12 micrograms/kg, range < 12-238 micrograms/kg). A second method of analysis employing inductively coupled plasma-mass spectrometry (ICP-MS) was developed which provided independent confirmation of the presence of bromate in these retail samples. The method gave a mean recovery of 71% from five spiked samples and a detection limit of 20 micrograms/kg. The GC and ICP-MS methods were compared by performing replicate analyses of a bread sample prepared with bromate-treated flour. Quantitative agreement between the two techniques was good. The precision of the ICP-MS technique (CV 12%) proved better than that found for the GC method (CV 18%). The Potassium Bromate (Prohibition as a Flour Improver) Regulation 1990 came into force on 1 April 1990 (Statutory Instrument 1990 Number 399).(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic transthoracic sympathectomy: successful in hyperhidrosis but can the indications be extended?

Endoscopic transthoracic sympathectomy (ETS) has recently become established as a successful treatment for severe palmar and axillary hyperhidrosis. In this unit the indications for ETS have been broadened to include patients with Raynaud's syndrome and critical upper limb ischaemia and this paper is primarily concerned with analysing outcome in relation to the indication for operation. In all, 68 operations have been attempted in 40 patients and complete follow-up details are available on 62 treated limbs. One operation was a technical failure because of an obliterated pleural cavity. In the hyperhidrosis group (n = 28), all the affected areas showed symptomatic improvement at a median follow-up of 17 months. In the Raynaud's group (n = 30), 28 limbs (93%) were improved to some degree at the time of discharge, but at a median follow-up of 18 months only 15 limbs (50%) remained symtomatically improved to some degree. The four upper limbs treated for critical ischaemia were improved by ETS and no amputations were necessary. Significant postoperative chest pain was noted by nine patients (23%). There were three postoperative pneumothoraces, two intercostobrachial neuralgias and one transient Horner's syndrome. The cosmetic result was reported as excellent or good by 97% of patients. As with other forms of surgical thoracic sympathectomy, excellent early results are not maintained in the longer term when ETS is used to treat Raynaud's syndrome. Nevertheless, the greater simplicity and lower morbidity of the endoscopic method suggest that it can be offered to Raynaud's sufferers with greater impunity than open sympathectomies.

Effect of human leucocyte antigen matching on the incidence of acute rejection in renal transplantation

The influence of human leucocyte antigen (HLA) matching on the incidence of acute rejection and graft survival was examined in 181 consecutive patients receiving cadaveric renal transplants. Allografts with better HLA-DR and HLA-B matching showed significantly lower rejection rates than less well matched grafts on both univariate (rejection rates 25, 62 and 82 per cent for zero, one and two DR mismatches; P < 0.001) and multivariate analysis. Rejection episodes occurred earlier in mismatched grafts (P < 0.001). Superior matching was associated with improved graft function at 1 year after transplantation (mean serum creatinine level 137, 180 and 225 mumol l-1 for zero, one and two DR mismatches; P < 0.05). No association was, however, demonstrated between the degree of matching and overall graft survival. Good HLA matching reduces the number of acute rejection episodes, producing significant savings in drug costs and hospital stay. Long-term graft function is improved and minimizing early graft damage helps to avoid later development of chronic rejection.

Obesity as a risk factor in major reconstructive vascular surgery

In a prospective analysis of 150 consecutive major vascular reconstructions, 104 patients were of normal weight (NW), 33 were overweight (OW) and 13 were obese (OB), as defined by body mass index calculations (BMI = kg/m2). Wound infections were more common in OW than NW patients (10/33 versus 10/104, p < 0.01) and in the OB compared to the NW group (4/13 versus 10/104, p < 0.05). Wound dehiscence was more common in the combined OW and OB groups than the NW patients (3/46 versus 0/104, p < 0.01). Chest infections were more common in OB (4/13) than NW (9/104) patients (p < 0.02). Median (interquartile range) in-patient stay was longer in OB patients [34 (15-41) days] compared to OW [14 (10-19) days, p < 0.001] and NW [11 (8-15) days; p < 0.001] patients. Nonetheless, there were no significant differences in the rates of more major complications or operative mortality between the three groups and early infrainguinal graft patency and limb salvage rates were not different. Only one prosthetic graft infection occurred in this series. In conclusion, despite the higher risk of infective complications, major vascular reconstruction can be performed safely in overweight and obese patients.

Effect of nifedipine on renal transplant rejection

The effect of early nifedipine therapy on acute renal allograft rejection was studied in 170 adult cadaveric transplant recipients. Acute rejection occurring in the first 3 months after transplantation was diagnosed by Tru-cut biopsy and the severity of each rejection episode assessed histologically. The incidence of acute rejection was significantly lower in patients treated with nifedipine (29 of 80; 36 per cent) than in controls (52 of 90; 58 per cent) (P < 0.01) and there was a higher proportion of histologically mild rejection episodes in the former group (P < 0.01). Multivariate analysis confirmed that nifedipine exerted a significant independent effect on the incidence of early acute rejection. Other factors identified in the multivariate model as influencing rejection were human leucocyte antigen (HLA) matching at the DR locus, blood level of cyclosporin during the first week, HLA matching at the B locus, donor age and donor sex. The 1-year graft survival rate was 88.6 per cent in patients given nifedipine and 63.8 per cent in controls (P < 0.02). These data suggest that nifedipine therapy has a useful role in human renal transplantation.

Different patterns of neuropathological disease in rhesus monkeys infected by simian immunodeficiency virus, and their relation to the humoral immune response

The brains of 21 rhesus monkeys inoculated with SIVMAC251 were examined after intervals ranging from 3 to 27 months and compared with five uninoculated controls. Eighteen animals became infected and individually exhibited several distinct patterns of disease. Nine (50%) had largely intramural leptomeningeal venous infiltrates (LMVI) without multinucleate giant cells (MGC) or foamy macrophages. Three (17%) had only MGC lesions, involving the cerebral parenchyma. One had both patterns and five (33%) neither. The controls had sparse and tiny LMVI only, similar to three inoculated animals that did not become infected. Immunohistochemistry showed the predominance of T and B lymphocytes in LMVI and choroid plexus mononuclear lesions but a predominance of macrophages over lymphocytes in the MGC lesions. Specific disease patterns differed in their association with the humoral immune response. Animals with LMVI were all hypergammaglobulinaemic when killed compared to pre-inoculation levels, and the size of the change in serum immunoglobulin concentration was positively correlated with a quantitative index of LMVI density. Furthermore, their post-mortem lymph node histology was hyperplastic. In contrast, animals found at autopsy to have MGC brain lesions were hypogammaglobulinaemic compared to preinoculation. The results are consistent with two phases in SIV-associated disease: one characterized by LMVI and hypergammaglobulinaemia and another featuring MGC and hypogammaglobulinaemia.