Covert stroke after non-cardiac surgery: a prospective cohort study.

BACKGROUND: Overt stroke after non-cardiac surgery has a substantial impact on the duration and quality of life. Covert stroke in the non-surgical setting is much more common than overt stroke and is associated with an increased risk of cognitive decline and dementia. Little is known about covert stroke after non-cardiac, non-carotid artery surgery. METHODS: We undertook a prospective, international cohort study to determine the incidence of covert stroke after non-cardiac, non-carotid artery surgery. Eligible patients were ≥65 yr of age and were admitted to hospital for at least three nights after non-cardiac, non-carotid artery surgery. Patients underwent a brain magnetic resonance study between postoperative days 3 and 10. The main outcome was the incidence of perioperative covert stroke. RESULTS: We enrolled a total of 100 patients from six centres in four countries. The incidence of perioperative covert stroke was 10.0% (10/100 patients, 95% confidence interval 5.5-17.4%). Five of the six centres that enrolled patients reported an incident covert stroke, and covert stroke was found in patients undergoing major general (3/27), major orthopaedic (3/41), major urological or gynaecological (3/22), and low-risk surgery (1/12). CONCLUSIONS: This international multicentre study suggests that 1 in 10 patients ≥65 yr of age experiences a perioperative covert stroke. A larger study is required to determine the impact of perioperative covert stroke on patient-important outcomes. CLINICAL TRIAL REGISTRATION: NCT01369537.

InVO4/TiO2 composite for visible-light photocatalytic degradation of 2-chlorophenol in wastewater.

InVO4/TiO2 composite was synthesized via amalgamation of InVO4 with TiO2 (Degussa P-25) powders. Application of the produced composite was evaluated as a catalyst for visible-light photocatalytic degradation of 2-chlorophenol (2-CP) in synthetic wastewater solutions. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy energy dispersive X-ray microanalyses and nitrogen physisorption. The degradation of 2-CP was affected by solution pH, light intensity, photocatalyst dosage and 2-CP initial concentration. InVO4/TiO2 showed higher photocatalytic degradation of 2-CP as compared with Degussa P-25 TiO2. Complete degradation of 2-CP was achieved with the InVO4/TiO2 catalyst under optimized conditions (1 g/L catalyst with a pollutant concentration of 50 mg/L at solution pH 5 and irradiation time of 180 min). Comparatively, 2-CP degradation efficiency of 50.5% was achieved with the TiO2 (Degussa P-25) at the same experimental conditions. The study confirmed that InVO4/TiO2 has high potential for degradation of 2-CP from wastewater under visible-light irradiation.

The pharmacology and therapeutic relevance of endocannabinoid derived cyclo-oxygenase (COX)-2 products.

The discovery of anandamide and 2-arachidonyl glycerol (2-AG) as naturally occurring mammalian endocannabinoids has had important and wide-reaching therapeutic implications. This, to a large extent, ensues from the complexity of endocannabinoid biology. One facet of endocannabinoid biology now receiving increased attention is the cyclo-oxygenase-2 (COX-2) derived oxidation products. Anandamide and 2-AG are oxidized to a range of PG-ethanolamides and PG-glyceryl esters that closely approaches that of the prostaglandins (PGs) formed from arachidonic acid. The pharmacology of these electrochemically neutral PG-ethanolamides (prostamides) and PG-glyceryl esters appears to be unique. No meaningful interaction with natural or recombinant prostanoid receptors is apparent. Nevertheless, in certain cells and tissues, prostamides and PG-glyceryl esters exert potent effects. The recent discovery of selective antagonists for the putative prostamide receptor has been a major advance in further establishing prostamide pharmacology as an entity distinct from prostanoid receptors. Since discovery of the prototype prostamide antagonist (AGN 204396), rapid progress has been made. The latest prostamide antagonists (AGN 211334-6) are 100 times more potent than the prototype and are, therefore, sufficiently active to be used in living animal studies. These compounds will allow a full evaluation of the role of prostamides in health and disease. To date, the only therapeutic application for prostamides is in glaucoma. The prostamide analog, bimatoprost, being the most effective ocular hypotensive drug currently available. Interestingly, PGE(2)-glyceryl ester and its chemically stable analog PGE(2)-serinolamide also lower intraocular pressure in dogs. Nevertheless, the therapeutic future of PGE(2)-glyceryl ester is more likely to reside in inflammation.

Identification and pharmacological characterization of the prostaglandin FP receptor and FP receptor variant complexes.

BACKGROUND AND PURPOSE: A prostamide analogue, bimatoprost, has been shown to be effective in reducing intraocular pressure, but its precise mechanism of action remains unclear. Hence, to elucidate the molecular mechanisms of this effect of bimatoprost, we focused on pharmacologically characterizing prostaglandin FP receptor (FP) and FP receptor variant (altFP) complexes. EXPERIMENTAL APPROACH: FP receptor mRNA variants were identified by reverse transcription-polymerase chain reaction. The FP-altFP4 heterodimers were established in HEK293/EBNA cells co-expressing FP and altFP4 receptor variants. A fluorometric imaging plate reader was used to study Ca2+ mobilization. Upregulation of cysteine-rich angiogenic protein 61 (Cyr61) mRNA was measured by Northern blot analysis, and phosphorylation of myosin light chain (MLC) by western analysis. KEY RESULTS: Six splicing variants of FP receptor mRNA were identified in human ocular tissues. Immunoprecipitation confirmed that the FP receptor is dimerized with altFP4 receptors in HEK293/EBNA cells co-expressing FP and altFP4 receptors. In the studies of the kinetic profile for Ca2+ mobilization, prostaglandin F2alpha (PGF2alpha) elicited a rapid increase in intracellular Ca2+ followed by a steady state phase. In contrast, bimatoprost elicited an immediate increase in intracellular Ca2+ followed by a second phase. The prostamide antagonist, AGN211335, selectively and dose-dependently inhibited the bimatoprost-initiated second phase of Ca2+ mobilization, Cyr61 mRNA upregulation and MLC phosphorylation, but did not block the action of PGF2alpha. CONCLUSION AND IMPLICATIONS: Bimatoprost lacks effects on the FP receptor but may interact with the FP-altFP receptor heterodimer to induce alterations in second messenger signalling. Hence, FP-altFP complexes may represent the underlying basis of bimatoprost pharmacology.

Factors associated with use of psychiatric intensive care and seclusion in adult inpatient mental health services.

AIMS: Within acute psychiatric inpatient services, patients exhibiting severely disturbed behaviour can be transferred to a psychiatric intensive care unit (PICU) and/or secluded in order to manage the risks posed to the patient and others. However, whether specific patient groups are more likely to be subjected to these coercive measures is unclear. Using robust methodological and statistical techniques, we aimed to determine the demographic, clinical and behavioural predictors of both PICU and seclusion. METHODS: Data were extracted from an anonymised database comprising the electronic medical records of patients within a large South London mental health trust. Two cohorts were derived, (1) a PICU cohort comprising all patients transferred from general adult acute wards to a non-forensic PICU ward between April 2008 and April 2013 (N = 986) and a randomly selected group of patients admitted to general adult wards within this period who were not transferred to PICU (N = 994), and (2) a seclusion cohort comprising all seclusion episodes occurring in non-forensic PICU wards within the study period (N = 990) and a randomly selected group of patients treated in these wards who were not secluded (N = 1032). Demographic and clinical factors (age, sex, ethnicity, diagnosis, admission status and time since admission) and behavioural precursors (potentially relevant behaviours occurring in the 3 days preceding PICU transfer/seclusion or random sample date) were extracted from electronic medical records. Mixed effects, multivariable logistic regression analyses were performed with all variables included as predictors. RESULTS: PICU cases were significantly more likely to be younger in age, have a diagnosis of bipolar disorder and to be held on a formal section compared with patients who were not transferred to PICU; female sex and longer time since admission were associated with lower odds of transfer. With regard to behavioural precursors, the strongest predictors of PICU transfer were incidents of physical aggression towards others or objects and absconding or attempts to abscond. Secluded patients were also more likely to be younger and legally detained relative to non-secluded patients; however, female sex increased the odds of seclusion. Likelihood of seclusion also decreased with time since admission. Seclusion was significantly associated with a range of behavioural precursors with the strongest associations observed for incidents involving restraint or shouting. CONCLUSIONS: Whilst recent behaviour is an important determinant, patient age, sex, admission status and time since admission also contribute to risk of PICU transfer and seclusion. Alternative, less coercive strategies must meet the needs of patients with these characteristics.

Presacral abscess as a rare complication of sacral nerve stimulator implantation.

A 50-year-old man with intractable anal pain attributed to proctalgia fugax underwent insertion of a sacral nerve stimulator via the right S3 vertebral foramen for pain control with good symptomatic relief. Thirteen months later, he presented with signs of sepsis. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a large presacral abscess. MRI demonstrated increased enhancement along the pathway of the stimulator electrode, indicating that the abscess was caused by infection introduced at the time of sacral nerve stimulator placement. The patient was treated with broad spectrum antibiotics, and the sacral nerve stimulator and electrode were removed. Attempts were made to drain the abscess transrectally using minimally invasive techniques but these were unsuccessful and CT guided transperineal drainage was then performed. Despite this, the presacral abscess progressed, developing enlarging gas locules and extending to the pelvic brim to involve the aortic bifurcation, causing hydronephrosis and radiological signs of impending sacral osteomyelitis. MRI showed communication between the rectum and abscess resulting from transrectal drainage. In view of the progressive presacral sepsis, a laparotomy was performed with drainage of the abscess, closure of the upper rectum and formation of a defunctioning end sigmoid colostomy. Following this, the presacral infection resolved. Presacral abscess formation secondary to an infected sacral nerve stimulator electrode has not been reported previously. Our experience suggests that in a similar situation, the optimal management is to perform laparotomy with drainage of the presacral abscess together with simultaneous removal of the sacral nerve stimulator and electrode.

Management of an acute catecholamine-induced cardiomyopathy and circulatory collapse: a multidisciplinary approach.

A phaeochromocytoma (PC) is a rare, catecholamine-secreting neuroendocrine tumour arising from the adrenal medulla. Presenting symptoms of this rare tumour are highly variable but life-threatening multiorgan dysfunction can occur secondary to catecholamine-induced hypertension or hypotension and subsequent cardiovascular collapse. High levels of circulating catecholamines can induce an acute stress cardiomyopathy, also known as Takotsubo cardiomyopathy. Recent studies have focused on early diagnosis and estimation of the prevalence of acute stress cardiomyopathy in patients with PC, but very little is reported about management of these complex cases. Here, we report the case of a 38-year-old lady who presented with an acute Takotsubo or stress cardiomyopathy and catecholamine crisis, caused by an occult left-sided 5 cm PC. The initial presenting crisis manifested with symptoms of severe headache and abdominal pain, triggered by a respiratory tract infection. On admission to hospital, the patient rapidly deteriorated, developing respiratory failure, cardiogenic shock and subsequent cardiovascular collapse due to further exacerbation of the catecholamine crisis caused by a combination of opiates and intravenous corticosteroid. An echocardiogram revealed left ventricular apical hypokinesia and ballooning, with an estimated left ventricular ejection fraction of 10-15%. Herein, we outline the early stabilisation period, preoperative optimisation and intraoperative management, providing anecdotal guidance for the management of this rare life-threatening complication of PC. LEARNING POINTS: A diagnosis of phaeochromocytoma should be considered in patients presenting with acute cardiomyopathy or cardiogenic shock without a clear ischaemic or valvular aetiology.Catecholamine crisis is a life-threatening medical emergency that requires cross-disciplinary expertise and management to ensure the best clinical outcome.After initial resuscitation, treatment of acute catecholamine-induced stress cardiomyopathy requires careful introduction of alpha-blockade followed by beta-blockade if necessary to manage ß-receptor-mediated tachycardia.Prolonged α-adrenergic receptor stimulation by high levels of circulating catecholamines precipitates arterial vasoconstriction and intravascular volume contraction, which can further exacerbate hypotension. Invasive pressure monitoring can aid management of intravascular volume in these complex patients.

Examination of the sensitivity of T cells to Fas ligation: induction of allospecific apoptosis.

BACKGROUND: Alloantigen-reactive T cells represent the major barrier to successful organ transplantation. However, it has been shown that cotransplantation of Fas ligand (FasL)-expressing cells can induce functional allograft tolerance in some model systems. In this study, the basis for this tolerance was investigated using a sensitive in vitro assay system. METHODS: T lymphocytes were activated by coculture with an allogeneic Epstein Barr virus-transformed B-cell line. Samples of the lymphocytes were taken daily and treated with agonistic anti-Fas antibodies or FasL-expressing cells. The time in culture required for development of optimal sensitivity to Fas-mediated apoptosis was assessed by Tdt-mediated nick end labeling (TUNEL) staining and the JAM assay of DNA fragmentation. After the induction of optimal apoptosis, a series of experiments was performed to assess the response of the T-cell population to antigen-specific rechallenge. RESULTS: Treatment of the allospecific lymphocyte population with anti-Fas antibodies or Fas-L-expressing cells did not induce apoptosis efficiently until between 6 and 7 days after initiation of the mixed lymphocyte culture; this time corresponded with decreases in the ambient interleukin 2 concentration and in Bcl-2 expression. In addition, induction of apoptosis by treatment with the agonistic anti-Fas antibody reduced the lymphoproliferative response of the T-cell population after antigen-specific rechallenge. CONCLUSIONS: These results give an important indication of the mechanism by which FasL-expressing third-party cells can reduce an allospecific T-cell response by an apoptotic mechanism. Furthermore, they demonstrate that apoptotic tolerance in vivo may only occur after the prolonged period of potentially graft-damaging T-cell activation required for acquisition of sensitivity to Fas-mediated apoptosis.

HIV type 1 protease inhibitors fail to inhibit HTLV-I Gag processing in infected cells.

Protease inhibitors are currently the most effective antiviral agents against human immunodeficiency virus type 1 (HIV-1). In this study we determined the effect of four HIV-1 protease inhibitors on human T cell leukemia virus type 1 (HTLV-I). Rhesus monkey cells infected with HTLV-I were treated with different concentrations of indinavir, saquinavir, ritonavir, or nelfinavir. The effect of these inhibitors was monitored through their effect on the processing efficiency of the viral Gag protein in cells, the natural substrate for the viral protease. These inhibitors failed to block processing of HTLV-I Gag. To confirm these findings, human cells were cotransfected with plasmids encoding infectious copies of HIV-1 and HTLV-I, and the cells were subsequently treated with these same HIV-1 protease inhibitors. At concentrations between 5 and 50 times the IC50 for inhibition of HIV-1 replication, inhibition of HIV-1 Gag cleavage was apparent. In contrast, no effect on HTLV-I Gag processing was seen. At higher concentrations, HIV-1 Gag processing was essentially completely inhibited whereas HTLV-I Gag cleavage was still unaffected. Thus, these inhibitors are not effective inhibitors of HTLV-I Gag processing. Sequence alignments of the HIV-1 and HTLV-I viral proteases and processing sites suggest that the active site of the HTLV-I protease may have subtle differences in substrate recognition compared with the HIV-1 protease.

Increased serum enzyme activity in microwave-exposed rats.

Heat stable serum enzymes were studied in rats exposed to microwaves (2.45 GHz, 120 Hz amplitude modulated) 24 hr after a single 4-hr exposure or immediately after 3 and 10 exposures to 0.1 to 55 mW/cm2. In addition, stable colonic temperature at 41.5 degrees C for 30 min was maintained by microwave exposure in a group of five rats under barbiturate anesthesia. Alkaline phosphatase and lactic dehydrogenase did not increase as a result of microwave exposure. Increased serum glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) were noted in the 41.5 degrees C group 24 hr after exposure. A threshold body temperature for acute cellular injury after microwave exposure was demonstrated. The acute cellular injury could be in the liver. These mild elevations in the serum enzyme levels (mean +/- SE, GOT = 167 +/- 40 U/liter: GPT = 74 +/- 26 U/liter) indicated that the injuries were not accompanied by any significant sequelae in the rat. From this threshold and colonic temperature (41.5 degrees C for 30 min) in barbiturate-anesthetized, microwave-exposed rats, we derived a tentative threshold for the whole-body average absorption rate at 14 W/kg (70 mW/cm2 at 2.45 GHz for adult rats) for 4 hr. This tentative threshold is subject to changes by duration of exposure and by compounding variables influencing maintenance of body temperature.

The relationship of decreased serum thyrotropin and increased colonic temperature in rats exposed to microwaves.

Although decreased serum thyrotropin (TSH) concentration has been found to be part of the endocrine response pattern in rats exposed to microwaves and other stimuli, the response of individual endocrine organs was not activated simultaneously by a given irradiance. Therefore, analytical evaluation of the function of endocrine organs individually as well as collectively is required to characterize the extent of biological involvement in microwave exposure. We have studied the changes in TSH concentration in unanesthetized rats exposed to 2.45 GHz amplitude modulated (120 Hz) microwaves in the far field for 2 and 4 h, between 0 and 55 mW/cm2, and from 1 to 10 times to demonstrate any possible cumulation, acclimation, or sensitization process. Ether inhalation was administered to test the responsiveness of TSH in groups of rats that failed to respond to microwave exposure by lowering TSH concentration. In addition, groups of rats were sampled 24 h after microwave exposure to test the persistency of the microwave effect on serum TSH concentration. Results showed that TSH concentration decreased in rats after microwave exposure. Influence of microwave exposure on serum TSH concentration was independent of the number of exposures indicating absence of cumulation, acclimation, or sensitization. The microwave effect on serum TSH could be dependent on duration of exposure. Decreased TSH concentration was usually accompanied by increased colonic temperature. For 4-h exposure, the lowest irradiance was 20 mW/cm2 or a 0.3 degree C increase in colonic temperature independent of the number of exposures. For 2-h exposure, the lowest irradiance was 30 mW/cm2 or a 1.1 degree C increase in colonic temperature regardless of the number of exposures. All the rats exposed at 10 mW/cm2 for 2 h had a lower TSH concentration than those of sham-exposed rats. Occasionally, significant reduction in TSH concentration could not be found in rats exposed to 20 or 25 mW/cm2 for 2 h. None of the rats exposed at an irradiance lower than 10 mW/cm2 had any change in TSH concentration. Failure of change in TSH concentration in response to microwave exposure was not a reflection of a deficiency since these rats responded to ether inhalation by lowering their TSH concentration. The effect of microwave exposure on TSH concentration was not persistent after exposure. The relation between TSH concentration and colonic temperature was curvilinear (exponential). From these results, two mechanisms and their implications for man were discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum-thyroxine levels in microwave-exposed rats.

The nature of the response of the thyroid gland in animals exposed to microwave irradiation is controversial. An enlarged thyroid and an increase of radioiodine uptake in microwave workers have been reported. Absence of thyroid disorders has also been reported in other exposed populations. Animal experimentation has contributed to the controversy because both increased and decreased thyroid functions have been reported. The thyroxine concentration in rats as representative of thyroid function in animals exposed to 2.45-GHz, 120-Hz amplitude-modulated microwaves has been studied. Comparison was made between thyroxine concentrations in microwave- and sham-exposed rats by Student's t test. After a 1-hr exposure, an increased thyroxine concentration was found in rats exposed at 40 and 70 mW/cm2, but not at 1, 5, 10, 20, 50, or 60 mW/cm2. After a 2-hr exposure, increased thyroxine concentration was noted in rats exposed at 25, 30, and 40 mW/cm2, but not at 1, 5, 10, and 20 mW/cm2. After a 4-hr exposure, thyroxine concentration increased in rats exposed at 1 mW/cm2 and decreased in rats exposed at 20 mW/cm2; but changes were not noted at 5 or 10 mW/cm2. Other experiments included animals that were exposed once for 4 hr (0.1, 1, 10, 25, and 40 mW/cm2), sampled 24 hr after a 4-hr exposure (0.1, 1, 10, 25, and 40 mW/cm2), or exposed for 4 hr 3 times (1, 10, 20, 30, 40, and 55 mW/cm2) and 10 times (1, 10, 20, 25, 30, and 40 mW/cm2), to evaluate the consistency of the thyroxine response. None of the rats in these experiments displayed any alteration of thyroxine concentration, except that decreased thyroxine was noted in rats exposed at 40 mW/cm2 for the third time. These studies covered a long time span; rats from two commercial sources (BS and CR) were used and subjected to different numbers of exposures, and therefore these data were evaluated for their stability. Two factors could influence the result significantly, i.e., source of animal and number of sham exposures. Rats used in the 2-hr exposures were from two different commercial sources; rats from CR had a higher (but normal) thyroxine concentration than did rats from BS. Therefore the data of these animals were separated by commercial source for reevaluation. Instead of increased thyroxine concentration in rats exposed at 25, 30, and 40 mW/cm2, changes were not noted in any microwave-exposed rats. The influence of sham exposure revealed that appropriate concurrent control and specification of animal source are needed in longitudinal studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of microwaves on the adrenal cortex.

Six-hundred-and-one male Long-Evans rats were used to study the effect of microwaves on adrenocortical secretion. Power density ranged from 0.1 to 55 mW/cm2 (SAR 0.02 to 11 W/kg). The microwave signal was 2.45 GHz amplitude modulated at 120 Hz. Serum corticosterone (CS) concentration was used as an index of adrenocortical function. Ten different exposure protocols were used to identify confounding factors influencing the sensitivity of adrenal cortex to microwave exposure. Increases in CS concentration were proportional to power density or colonic temperature and inversely proportional to the baseline CS. Increased CS concentration was never observed without increased colonic temperature and was not persistent 24 h after exposure. Acclimation (reduction in magnitude of response) could be noted after the tenth exposure. Facilitated heat loss attenuated the magnitude of CS increases by limiting the degree of hyperthermia. Ethanol enhanced the hyperthermic response and desensitized the adrenal response to microwave hyperthermia by increased baseline CS. Ether stimulated adrenal secretion irrespective of previous microwave exposure or adrenal stimulation induced by microwaves. Minor inhibition was also noted occasionally as decreased CS concentration at lower intensity (less than 20 mW/cm2) and decreased postexposure urinary CS excretion at 40 mW/cm2. Adrenal stimulation required minimally a 20 mW/cm2 (4 W/kg) or 0.7 degrees C increase in colonic temperature. An SAR lower than 4 W/kg may stimulate adrenal secretion by potentiating the hyperthermic effect if the ambient temperature is well above 24 degrees C.

Effects of microwaves on three different strains of rats.

Confounding factors influencing the sensitivity of biological indicators of microwave exposure--lethality, colonic temperature (Tco), decreased body mass (dW), corticosterone (CS), thyrotropin (TSH), thyroxine (T4), free thyroxine (FT4), and prolactin (PRL) concentration--were studied in Long-Evans (LE), Wistar-Kyoto (WKY), and spontaneous hypertensive (SHR) rats. The microwave signal was 2.45 GHz amplitude modulated at 120 Hz. Test power density ranged from 1 to 50 mW/cm2 for 2 h. In contrast to the LE and WKY rats, the SHR rats were characterized by intolerance (death) between 40 and 50 mW/cm2 (9.2 to 11.5 W/kg). The lowest lethal Tco was 41.1 degrees C. Survivors including all the LE and WKY rats were capable of maintaining Tco lower than 41.0 degrees C. In general, strain of rat seemed to influence other bioindicators and to interact with power density on these bioindicators. Except for Tco and PRL, baseline for the various bioindicators varied among the different strains of rats. Responses of T4 and FT4 were limited in magnitude and inconsistent among strains of rats. In general, the magnitude of Tco increase was more pronounced in SHR than in WKY. Differences between SHR and LE, however, could be noted only at 1, 10, and 50 mW/cm2. Increased Tco, increased magnitude of Dw, increased CS, decreased TSH, and increased PRL (stress reactions) could be noted in rats exposed to 30 mW/cm2 (approximately 6 W/kg) or higher, irrespective of strain. At least two of three strains of rats (WKY and SHR) exposed to 20 mW/cm2 (approximately 4 W/kg) showed changes in Tco, CS, TSH, and PRL. At 10 mW/cm2 (2 W/kg), increased Tco could be found in all three strains of rats accompanied by changes in dW and TSH in LE, TSH in WKY, and dW and CS in SHR. At 1 mW/cm2 (0.2 W/kg), increased Tco could be noted in two of three strains (LE and SHR) and increased PRL in LE only. The smallest Tco increases for a consistent response (increased magnitude of response with power density) were 1.59 degrees C for dW, 0.70 degrees C for CS, 0.24 degrees C for TSH, and 0.97 degrees C for PRL. Tentatively, the threshold intensity for response to microwave exposure for rats could be considered as 2 W/kg or a 0.24 degrees C increase at 24 degrees C ambient temperature.

Endogenous avidin-binding activity in human lymphoid tissue.

Biotin-avidin systems can be used as an alternative to indirect antibody sandwich methods in the detection of T lymphocyte subsets in cryostat sections of human lymphoid tissue. Appreciable endogenous avidin binding activity (EABA) has been found, however, in human lymph nodes and tonsils. Such EABA can be a source of false positive staining when biotin-avidin detection systems are used to identify cells in cryostat sections. The finding that avidin binding cells may also contain endogenous peroxidase activity and are morphologically similar to histiocytes suggests that such cells may be of histiocytic lineage. EABA is not seen in intrafollicular "tingible body" macrophages, however, and only rarely in medullary sinus histiocytes. Thus further studies are necessary to identify the lineage of avidin binding cells in lymphoid tissues. EABA can be effectively blocked by treatment of cryostat sections with 1% avidin followed by 0.01% biotin before specific staining with biotinylated antibodies and avidin-peroxidase or avidin-fluorochrome conjugates.

Survey of infection in patients receiving antibody replacement treatment for immune deficiency.

BACKGROUND: Primary antibody deficiency disorders are a heterogeneous group of disorders, which are treated by regular infusions of immunoglobulin. Despite replacement treatment, patients remain susceptible to infection. Effective management of infections is necessary to prevent the complications of chronic infection. AIMS: This retrospective survey of clinical practice examined the management of infections in patients who receive immunoglobulin replacement for immune deficiency. METHODS: Patients who received immunoglobulin replacement treatment in Newcastle during the year 2000 were identified. Medical records were reviewed. Basic clinical information and details of immunoglobulin replacement treatment were recorded. Episodes of infection were defined by documented symptoms, signs, or investigation results, and by the prescription of an antibiotic course. Details of episodes of infection and antimicrobial treatment were recorded. RESULTS: Thirty seven patients received immunoglobulin replacement during 2000. There were 101 episodes of infection. There was no correlation between the frequency of infection and the IgG trough value. Respiratory tract infections were most common (71 of 101). Where documented, 80% of infections were associated with clinical signs, 21% with pyrexia, and 64% with a raised C reactive protein value. Microbiological culture was performed in 30% of infections. Antimicrobial treatment was instituted along "best guess" lines in 99 of 101 episodes of infection. CONCLUSIONS: Management of respiratory tract infections represents the largest problem in antibody deficient patients. Greater use of microbiological culture might allow more effective prescription of antimicrobial treatment. The generation of treatment guidelines and improved communication with general practitioners could improve the management of all episodes of infection.

A rapid and simple procedure for the preparation of human lactate dehydrogenase-2 from erythrocytes using an ion-exchange mini-column.

We describe a simple ion-exchange chromatography technique for the rapid preparation of lactate dehydrogenase-2 from lysed human erythrocytes obtained either from plasma or serum clots. The procedure appears capable of scale-up to larger columns thus making it ideal as an initial step in a more extensive purification scheme.

Sister chromatid exchanges in Chinese hamster ovary cells exposed to high intensity pulsed ultrasound: inability to confirm previous positive results.

This study was undertaken in an attempt to determine a physical mechanism of action for a recently published report of a small but statistically significant increase in sister chromatid exchanges (SCEs) in Chinese hamster ovary cells exposed to high-intensity pulsed ultrasound. The "positive" report's protocol involved a sizeable chance of ultrasound beam impingement on the side wall of the cell exposure chamber. Ten experiments per regimen were conducted; the regimens included exposures of (a) chamber center, (b) chamber wall, (c) nine grid sites, 0.5 mm between sites, and (d) nine grid sites, 1.5 mm between sites. The last was an exact replication of the conditions previously reported to induce the small SCE effect. The results did not support the postulate of an increase in SCEs with the ultrasound exposures.

Two case reports of perineal hernia after laparoscopic abdominoperineal resection with a proposed modification to the operative technique.

Perineal hernia is a rare complication following laparoscopic abdominoperineal resection (APR) for rectal cancer. We present two case reports of perineal hernia following laparoscopic APR and discuss their management. We suggest that they developed because the pelvic peritoneum was left open during laparoscopic APR and propose that closure of the pelvic peritoneum should be routine in this operation.

Post-traumatic appendicular-cutaneous fistula: a case report.

Appendicular-cutaneous fistula is an uncommon condition that usually occurs as a complication of appendicitis. We report the case of a 28-year-old woman with a chronic appendicular-cutaneous fistula following a road traffic accident in which she sustained a penetrating injury to the abdomen.