Do high-protein diets have the potential to reduce gut barrier function in a sex-dependent manner?

PURPOSE

Impaired gut barrier function is associated with systemic inflammation and many chronic diseases. Undigested dietary proteins are fermented in the colon by the gut microbiota which produces nitrogenous metabolites shown to reduce barrier function in vitro. With growing evidence of sex-based differences in gut microbiotas, we determined whether there were sex by dietary protein interactions which could differentially impact barrier function via microbiota modification.

METHODS

Fermentation systems were inoculated with faeces from healthy males (n = 5) and females (n = 5) and supplemented with 0.9 g of non-hydrolysed proteins sourced from whey, fish, milk, soya, egg, pea, or mycoprotein. Microbial populations were quantified using fluorescence in situ hybridisation with flow cytometry. Metabolite concentrations were analysed using gas chromatography, solid phase microextraction coupled with gas chromatography-mass spectrometry and ELISA.

RESULTS

Increased protein availability resulted in increased proteolytic Bacteroides spp (p < 0.01) and Clostridium coccoides (p < 0.01), along with increased phenol (p < 0.01), p-cresol (p < 0.01), indole (p = 0.018) and ammonia (p < 0.01), varying by protein type. Counts of Clostridium cluster IX (p = 0.03) and concentration of p-cresol (p = 0.025) increased in males, while females produced more ammonia (p = 0.02), irrespective of protein type. Further, we observed significant sex-protein interactions affecting bacterial populations and metabolites (p < 0.005).

CONCLUSIONS

Our findings suggest that protein fermentation by the gut microbiota in vitro is influenced by both protein source and the donor's sex. Should these results be confirmed through human studies, they could have major implications for developing dietary recommendations tailored by sex to prevent chronic illnesses.

Effects of iron deficiency and iron supplementation at the host-microbiota interface: Could a piglet model unravel complexities of the underlying mechanisms?

Iron deficiency is the most prevalent human micronutrient deficiency, disrupting the physiological development of millions of infants and children. Oral iron supplementation is used to address iron-deficiency anemia and reduce associated stunting but can promote infection risk since restriction of iron availability serves as an innate immune mechanism against invading pathogens. Raised iron availability is associated with an increase in enteric pathogens, especially Enterobacteriaceae species, accompanied by reductions in beneficial bacteria such as Bifidobacteria and lactobacilli and may skew the pattern of gut microbiota development. Since the gut microbiota is the primary driver of immune development, deviations from normal patterns of bacterial succession in early life can have long-term implications for immune functionality. There is a paucity of knowledge regarding how both iron deficiency and luminal iron availability affect gut microbiota development, or the subsequent impact on immunity, which are likely to be contributors to the increased risk of infection. Piglets are naturally iron deficient. This is largely due to their low iron endowments at birth (primarily due to large litter sizes), and their rapid growth combined with the low iron levels in sow milk. Thus, piglets consistently become iron deficient within days of birth which rapidly progresses to anemia in the absence of iron supplementation. Moreover, like humans, pigs are omnivorous and share many characteristics of human gut physiology, microbiota and immunity. In addition, their precocial nature permits early maternal separation, individual housing, and tight control of nutritional intake. Here, we highlight the advantages of piglets as valuable and highly relevant models for human infants in promoting understanding of how early iron status impacts physiological development. We also indicate how piglets offer potential to unravel the complexities of microbiota-immune responses during iron deficiency and in response to iron supplementation, and the link between these and increased risk of infectious disease.

Hepcidin-Mediated Hypoferremia Disrupts Immune Responses to Vaccination and Infection

BACKGROUND

How specific nutrients influence adaptive immunity is of broad interest. Iron deficiency is the most common micronutrient deficiency worldwide and imparts a significant burden of global disease; however, its effects on immunity remain unclear.

METHODS

We used a hepcidin mimetic and several genetic models to examine the effect of low iron availability on T cells in vitro and on immune responses to vaccines and viral infection in mice. We examined humoral immunity in human patients with raised hepcidin and low serum iron caused by mutant TMPRSS6. We tested the effect of iron supplementation on vaccination-induced humoral immunity in piglets, a natural model of iron deficiency.

FINDINGS

We show that low serum iron (hypoferremia), caused by increased hepcidin, severely impairs effector and memory responses to immunizations. The intensified metabolism of activated lymphocytes requires the support of enhanced iron acquisition, which is facilitated by IRP1/2 and TFRC. Accordingly, providing extra iron improved the response to vaccination in hypoferremic mice and piglets, while conversely, hypoferremic humans with chronically increased hepcidin have reduced concentrations of antibodies specific for certain pathogens. Imposing hypoferremia blunted the T cell, B cell, and neutralizing antibody responses to influenza virus infection in mice, allowing the virus to persist and exacerbating lung inflammation and morbidity.

CONCLUSIONS

Hypoferremia, a well-conserved physiological innate response to infection, can counteract the development of adaptive immunity. This nutrient trade-off is relevant for understanding and improving immune responses to infections and vaccines in the globally common contexts of iron deficiency and inflammatory disorders.

FUNDING

Medical Research Council, UK.

Sexual Dimorphism in Immune Development and in Response to Nutritional Intervention in Neonatal Piglets

Although sex disparity in immunological function and susceptibility to various inflammatory and infectious disease is recognized in adults, far less is known about the situation in young infants during immune development. We have used an outbred piglet model to explore potential early sex disparity underlying both mucosal immune development and systemic responses to novel antigen. Despite similarities in intestinal barrier function and therefore, presumably, antigen exposure, females had less CD172⁺ (Sirp-α) antigen presenting cells and expression of MHCIIDR at 28 days old compared to males, along with greater regulatory T-cell numbers. This suggests that, during infancy, females may have greater potential for local immune regulation than their male counterparts. However, females also presented with significantly greater systemic antibody responses to injected ovalbumin and dietary soya. Females also synthesized significantly more IgA in mesenteric lymph nodes, whereas males synthesized more in caecal mucosa, suggesting that plasma cells were retained within the MLN in females, but increased numbers of plasma cells circulated through to the mucosal tissue in males. Significant effects of inulin and Bifidobacterium lactis NCC2818 on the developing immune system were also sex-dependent. Our results may start to explain inconsistencies in outcomes of trials of functional foods in infants, as distinction between males and females is seldom made. Since later functionality of the immune system is highly dependent on appropriate development during infancy, stratifying nutritional interventions by sex may present a novel means of optimizing treatments and preventative strategies to reduce the risk of the development of immunological disorders in later life.

Cardiac Leiomyosarcoma in a Cat Presenting for Bilateral Renal Neoplasia

A 10-year-old neutered female domestic longhair cat was presented to a tertiary care veterinary hospital for evaluation of a right renal mass that was identified incidentally on abdominal radiographs and classified further as a sarcoma based on fine needle aspiration cytology. Further diagnostic workup, including ultrasound and cytology, identified a sarcoma in the left kidney. After approximately 1 month of conservative medical management, the clinical condition deteriorated and the cat was humanely destroyed. Post-mortem examination confirmed bilateral renal masses with multifocal infarction and extensive necrosis, and further identified a large mass at the apex of the heart as well as multiple pulmonary nodules. Microscopical examination of the masses identified a population of poorly-differentiated neoplastic spindle cells, consistent with sarcoma. Immunohistochemically, the neoplastic cells expressed smooth muscle actin and muscle-specific actin, but were negative for myoglobin and factor VIII. Phosphotungstic acid-haematoxylin staining was unable to identify cross-striations in the neoplastic cells. Based on these results and the pattern of lesion distribution, the cat was diagnosed with cardiac leiomyosarcoma with pulmonary and bilateral renal metastasis.

Development of Immune Cells in the Intestinal Mucosa Can Be Affected by Intensive and Extensive Farm Environments, and Antibiotic Use

Epidemiological studies have demonstrated that exposure to farm environments during childhood can be linked to reductions in the incidence of immune disorders, but generating an appropriate model is difficult. 108 half-sibling piglets were born on either extensive (outdoor) or intensive (indoor) farms: at 1 day old, a subset of piglets from each litter were transferred to a high-hygiene isolator facility to create differences in rearing environment either during birth/first day or during the subsequent 56 days of life. Interactions between CD14, CD16, MHCIIDR, and capillary endothelium were assessed using four-color quantitative fluorescence immunohistology. Effects of birth and rearing environment on the antigen-presenting microenvironment of the proximal and distal jejunum (professional and stromal) were apparent at 5, 28, and 56 days after birth However, effects on CD4⁺CD25⁺Foxp3⁺ regulatory T-cells (T_regs) in the intestinal mucosa were apparent around weaning at 28 days but had disappeared by 56 days. These T_regs were reduced in the isolator piglets compared to their farm-reared siblings, but this effect was less marked in piglets born on the extensive farm and required administration of antibiotics. Our results suggest that there may be at least two windows of opportunity in which different farm environments were influencing immune development: one during the perinatal period (up to the first day of life), and one during later infancy. Furthermore, the differences on T_regs suggest that the effects of early life influences may be particularly critical around weaning.

Early intervention with Bifidobacterium lactis NCC2818 modulates the host-microbe interface independent of the sustained changes induced by the neonatal environment

Inflammatory and metabolic diseases can originate during early-life and have been correlated with shifts in intestinal microbial ecology. Here we demonstrate that minor environmental fluctuations during the early neonatal period had sustained effects on the developing porcine microbiota and host-microbe interface. These inter-replicate effects appear to originate during the first day of life, and are likely to reflect very early microbiota acquisition from the environment. We statistically link early systemic inflammation with later local increases in inflammatory cytokine (IL-17) production, which could have important enteric health implications. Immunity, intestinal barrier function, host metabolism and host-microbiota co-metabolism were further modified by Bifidobacterium lactis NCC2818 supplementation, although composition of the in situ microbiota remained unchanged. Finally, our robust model identified novel, strong correlations between urinary metabolites (eg malonate, phenylacetylglycine, alanine) and mucosal immunoglobulin (IgM) and cytokine (IL-10, IL-4) production, thus providing the possibility of the development of urinary ‘dipstick’ tests to assess non-accessible mucosal immune development and identify early precursors (biomarkers) of disease. These results have important implications for infants exposed to neonatal factors including caesarean delivery, antibiotic therapy and delayed discharge from hospital environments, which may predispose to the development of inflammatory and metabolic diseases in later life.

Kinetically Selective Inhibitors of Histone Deacetylase 2 (HDAC2) as Cognition Enhancers

Kinetically selective inhibitors of HDAC2 enhanced learning and memory in a CK-p25 mouse model of neurodegeneration.

Aiming towards the development of novel nootropic therapeutics to address the cognitive impairment common to a range of brain disorders, we set out to develop highly selective small molecule inhibitors of HDAC2, a chromatin modifying histone deacetylase implicated in memory formation and synaptic plasticity. Novel ortho-aminoanilide inhibitors were designed and evaluated for their ability to selectively inhibit HDAC2 versus the other Class I HDACs. Kinetic and thermodynamic binding properties were essential elements of our design strategy and two novel classes of ortho-aminoanilides, that exhibit kinetic selectivity (biased residence time) for HDAC2 versus the highly homologous isoform HDAC1, were identified. These kinetically selective HDAC2 inhibitors (BRD6688 and BRD4884) increased H4K12 and H3K9 histone acetylation in primary mouse neuronal cell culture assays, in the hippocampus of CK-p25 mice, a model of neurodegenerative disease, and rescued the associated memory deficits of these mice in a cognition behavioural model. These studies demonstrate for the first time that selective pharmacological inhibition of HDAC2 is feasible and that inhibition of the catalytic activity of this enzyme may serve as a therapeutic approach towards enhancing the learning and memory processes that are affected in many neurological and psychiatric disorders.

Direct experimental evidence that early-life farm environment influences regulation of immune responses

BACKGROUND

  In mammals, early-life environmental variations appear to affect microbial colonization and therefore competent immune development, and exposure to farm environments in infants has been inversely correlated with allergy development. Modelling these effects using manipulation of neonatal rodents is difficult due to their dependency on the mother, but the relatively independent piglet is increasingly identified as a valuable translational model for humans. This study was designed to correlate immune regulation in piglets with early-life environment.

METHODS

  Piglets were nursed by their mother on a commercial farm, while isolator-reared siblings were formula fed. Fluorescence immunohistology was used to quantify T-reg and effector T-cell populations in the intestinal lamina propria and the systemic response to food proteins was quantified by capture ELISA.

RESULTS

  There was more CD4(+) and CD4(+) CD25(+) effector T-cell staining in the intestinal mucosa of the isolator-reared piglets compared with their farm-reared counterparts. In contrast, these isolator-reared piglets had a significantly reduced CD4(+) CD25(+) Foxp3(+) regulatory T-cell population compared to farm-reared littermates, resulting in a significantly higher T-reg-to-effector ratio in the farm animals. Consistent with these findings, isolator-reared piglets had an increased serum IgG anti-soya response to novel dietary soya protein relative to farm-reared piglets.

CONCLUSION

  Here, we provide the first direct evidence, derived from intervention, that components of the early-life environment present on farms profoundly affects both local development of regulatory components of the mucosal immune system and immune responses to food proteins at weaning. We propose that neonatal piglets provide a tractable model which allows maternal and treatment effects to be statistically separated.

An improved technique for Soave trans-anal pull-through

AIM

To describe a new technique for the Soave trans-anal pull-through.

METHOD

After the mucosectomy during a Soave's procedure, a laparoscopic wound retractor was used to line the distal rectal segment to facilitate delivery of the proximal bowel through a narrow scarred pelvis.

RESULTS

The technique greatly assisted delivery of the proximal bowel and helped prevent mesenteric injury.

CONCLUSION

Soave trans-anal pull-through is a difficult operation that is largely confined to specialist centres. We describe an improvement to the technique that greatly facilitates the procedure.

Uncomplicated general anesthesia in the elderly results in cognitive decline: does cognitive decline predict morbidity and mortality?

Elderly surgical patients constitute a unique surgical group. They require special consideration in order to preempt the long term adverse effects of anesthesia. This paper examines the proposition that general anesthesia causes harm to elderly patients with its impact being felt long after the anesthetic agents are cleared from the body. One complication, Postoperative Cognitive Decline (POCD), is associated with the administration of anesthesia and deep sedation. Its' occurrence may herald an increase in morbidity and mortality. Based on both human and animal data, this paper outlines a unitary theoretical framework to explain these phenomena. If this hypothesis proves to be correct, anesthesiologist should consider regional rather than general anesthesia for equivalent surgical procedures to reduce POCD and consequently achieving superior patient outcome.

Effects of fenofibrate on lipid parameters in obese rhesus monkeys

Fenofibrate is a member of the fibrate class of hypolipidemic agents used clinically to treat hypertriglyceridemia and mixed hyperlipidemia. The fibrates were developed primarily on the basis of their cholesterol and triglyceride lowering in rodents. Fibrates have historically been ineffective at lowering triglycerides in experimentally-induced dyslipidemia in nonhuman primate models. The spontaneously obese rhesus monkey is a well-recognized animal model for the study of human obesity and type 2 diabetes, and many of these monkeys exhibit naturally occurring lipid abnormalities, including elevated triglycerides and low HDL cholesterol (HDL-C), similar to patients with type 2 diabetes. To explore whether the obese rhesus model was predictive of the lipid lowering effects of fibrates, we evaluated fenofibrate in six hypertriglyceridemic, hyperinsulinemic, nondiabetic animals in a 20-week, dose-escalating study. The study consisted of a 4-week baseline period, two treatment periods of 10 mg/kg twice daily (b.i.d) for 4 weeks and 30 mg/kg b.i.d. for 8 weeks, and a 4-week washout period. Fenofibrate (30 mg/kg b.i.d) decreased serum triglycerides 55% and LDL-C 27%, whereas HDL-C increased 35%. Apolipoproteins B-100 and C-III levels were also reduced 70% and 29%, respectively. Food intake, body weight, and plasma glucose were not affected throughout the study. Interestingly, plasma insulin levels decreased 40% during the 30 mg/kg treatment period, suggesting improvement in insulin sensitivity. These results support the use of obese rhesus monkey as an excellent animal model for studying the effects of novel hypolipidemic agents, particularly agents that impact serum triglycerides and HDL-C.

Identification of a subtype selective human PPARα agonist through parallel-array synthesis

Using solid-phase, parallel-array synthesis, a series of urea-substituted thioisobutyric acids was synthesized and assayed for activity on the human PPAR subtypes. GW7647 (3) was identified as a potent human PPARalpha agonist with approximately 200-fold selectivity over PPARgamma and PPARdelta, and potent lipid-lowering activity in animal models of dyslipidemia. GW7647 (3) will be a valuable chemical tool for studying the biology of PPARalpha in human cells and animal models of disease.

A selective peroxisome proliferator-activated receptor delta agonist promotes reverse cholesterol transport

The peroxisome proliferator-activated receptors (PPARs) are dietary lipid sensors that regulate fatty acid and carbohydrate metabolism. The hypolipidemic effects of the fibrate drugs and the antidiabetic effects of the glitazone drugs in humans are due to activation of the alpha (NR1C1) and gamma (NR1C3) subtypes, respectively. By contrast, the therapeutic potential of the delta (NR1C2) subtype is unknown, due in part to the lack of selective ligands. We have used combinatorial chemistry and structure-based drug design to develop a potent and subtype-selective PPARdelta agonist, GW501516. In macrophages, fibroblasts, and intestinal cells, GW501516 increases expression of the reverse cholesterol transporter ATP-binding cassette A1 and induces apolipoprotein A1-specific cholesterol efflux. When dosed to insulin-resistant middle-aged obese rhesus monkeys, GW501516 causes a dramatic dose-dependent rise in serum high density lipoprotein cholesterol while lowering the levels of small-dense low density lipoprotein, fasting triglycerides, and fasting insulin. Our results suggest that PPARdelta agonists may be effective drugs to increase reverse cholesterol transport and decrease cardiovascular disease associated with the metabolic syndrome X.

A regulatory cascade of the nuclear receptors FXR, SHP-1, and LRH-1 represses bile acid biosynthesis

Bile acids repress the transcription of cytochrome P450 7A1 (CYP7A1), which catalyzes the rate-limiting step in bile acid biosynthesis. Although bile acids activate the farnesoid X receptor (FXR), the mechanism underlying bile acid-mediated repression of CYP7A1 remained unclear. We have used a potent, nonsteroidal FXR ligand to show that FXR induces expression of small heterodimer partner 1 (SHP-1), an atypical member of the nuclear receptor family that lacks a DNA-binding domain. SHP-1 represses expression of CYP7A1 by inhibiting the activity of liver receptor homolog 1 (LRH-1), an orphan nuclear receptor that is known to regulate CYP7A1 expression positively. This bile acid-activated regulatory cascade provides a molecular basis for the coordinate suppression of CYP7A1 and other genes involved in bile acid biosynthesis.

How much work is required to puncture dura with Tuohy needles?

The effects of needle bevel orientation and cerebrospinal fluid (CSF) pressure on dural displacement and force required to penetrate cadaveric dura were studied using 40 samples. A constant hydrostatic pressure was applied to the subdural surface, either high or low, simulating the sitting and lateral positions. A 17-gauge Tuohy needle was advanced through the dura with the bevel oriented parallel or perpendicular to dural fibres. Travel distance and peak force at which dural penetration occurred were measured under both pressure conditions. The work required to produce dural penetration was calculated. Greater force and work were required to penetrate dura in the perpendicular orientation (P < 0.05), regardless of the subdural pressure exerted. Dural displacement was similar under both pressure conditions.

Which is most pungent: isoflurane, sevoflurane or desflurane?

We compared the pungency and tolerability of three inhaled anaesthetics in a randomized, double-blind study. Eighty-one unpremedicated patients (n = 27, each group) inhaled 2 MAC of isoflurane (2.3%), desflurane (12%) or sevoflurane (4%) for 60 s from an anaesthetic breathing circuit via a mask. Two blinded observers recorded coughing, complaints of burning and irritation, and how long the inhalation was tolerated. One sevoflurane patient coughed, but completed the study period, whereas 11 isoflurane patients and 20 desflurane patients coughed, objected verbally or removed the mask forcefully. All sevoflurane, 20 isoflurane and seven desflurane patients completed the study period (average 60, 49 and 33 s, respectively, P < 0.05). The irritability grading was: desflurane > isoflurane > sevoflurane (P < 0.05). Sevoflurane is the least irritating agent for inhalation at 2 MAC concentration.

Cardiopulmonary complications during laparoscopy: two case reports

Laparoscopic surgery is growing in popularity. As a result, laparoscopic procedures are being done on a broader and older patient population. These patients may have underlying cardiopulmonary disease that predisposes them to complications not seen in younger patients. Anesthesiologists should be aware of this possibility and of the problems inherent to the pneumoperitoneum necessary for laparoscopy. We present two cases involving elderly patients to illustrate cardiopulmonary complications that can occur during establishment or maintenance of the increased intra-abdominal pressures required for laparoscopic surgery. The first case describes a patient who developed bradycardia and asystole during insufflation for a laparoscopic hernia repair. The second case involves severe hypercarbia and a pneumothorax due to massive subcutaneous emphysema that developed during a laparoscopic colon resection.

Inhibition of ileal sodium-dependent bile acid transport by 2164U90

Inhibition of the ileal bile acid active transport system, previously shown to be mechanism underlying the hypocholesterolemic activity of 2164U90 in rodents, was further characterized in isolated intestinal preparations from three species. 2164U90 inhibited sodium-dependent transport of taurocholic acid by Caco-2 cells and by monkey and human ileal brush border membrane vesicles in a concentration-dependent manner with IC50s of 7 microM, 5 microM, and 2 microM, respectively. In rat ileal brush border membrane vesicles, 2164U90 was a competitive inhibitor of sodium-dependent taurocholic acid uptake with an estimated Ki of 1.8 +/- 0.2 microM. In anesthetized rats, 5 microM 2164U90 placed in the isolated distal ileum with 3 mM [3H]taurocholic acid decreased ileal uptake, transport into the bile, and transport rate of taurocholic acid by 31-35%. Stereospecificity of inhibition by 2164U90 was demonstrated by the relative inactivity of three other possible stereoisomers in rat ileal sacs and brush border membrane vesicles. 2164U90 did not inhibit sodium-dependent glucose transport by monkey jejunal brush border membrane vesicles, indicating that 2164U90 may be specific for the bile acid transporter. These results suggest that 2164U90 is a potent, selective, stereospecific, competitive inhibitor of the sodium-dependent bile acid transporter in the ileal mucosal cell brush border membrane.

Effects of 2164U90 on ileal bile acid absorption and serum cholesterol in rats and mice

2164U90, [(3R,5R)-trans-3-butyl-3-ethyl-2,3,4,5-tetrahydro-5-phenyl-1,4- benzothiazepine 1,1-dioxide], was found to be a potent inhibitor of the ileal bile acid active transport system. In vitro, 2164U90 decreased uptake and active transport of taurocholic acid by rat everted ileal sacs with IC50s of 4.0 microM and 1.5 microM, respectively. In vivo, 2164U90 produced dose-dependent increases in 23,25-75Se-labeled homocholic acid taurine (SeHCAT) fecal excretion in rats and mice at doses of 3-30 mg/kg and 1-10 mg/kg, respectively. In rats, 30 mg/kg 2164U90 was equivalent to 500 mg/kg cholestyramine. Two days oral administration of 10 mg/kg 2164U90 to rats decreased the bile concentrations of total bile acids 42%, orally administered [3H]taurocholic acid ([3H]TC) 82%, and cholesterol 35%. Cholestyramine (500 mg/kg) had effects similar to 2164U90 on total bile acid and orally administered [3H]TC concentrations but had no effect on biliary cholesterol. The hypocholesterolemic activity of 2164U90 was determined in cholesterol-cholic acid-fed rats and cholesterol-cholic acid-coconut oil-fed mice. 2164U90 inhibited the dietary-induced increase in dextran sulfate-precipitable lipoprotein cholesterol (VLDL+LDL) at doses comparable to doses needed to increase the fecal excretion of bile acids. These data indicate that 2164U90 decreases bile acid absorption by inhibiting the ileal bile acid active transport system, resulting in hypocholesterolemic activity.

Studies on muscle cells isolated from Schistosoma mansoni: a Ca(2+)-dependent K+ channel

Muscle cells from adult male Schistosoma mansoni have been isolated using a combination of papain digestions and mechanical dissociation procedures. The muscle fibres isolated in this way lacked nuclei but they did contract and relax in response to high [K+], a response which was blocked in the presence of Co2+. From this we conclude that the isolation procedure yields viable muscle fibres useful for physiological studies. Patch-clamp recordings taken from the isolated fibres show a variety of discrete ionic conductances. In inside-out patches one prominent channel was a Ca(2+)-activated K+ channel with a conductance of 195 pS and a selectivity greater than 10:1 for K+ over Na+, Cs+ or NH4+. Percentage open time was dependent on [Ca2+] at the intracellular face. With [Ca2+] at 1 microM or greater percentage open time was greater than 95%; at 0.1 microM it was less than 2%. No voltage sensitivity could be detected in the voltage range from -50 to -10 mV membrane potential. Ba2+ (10 mM), but neither tetraethylammonium nor 3,4-diaminopyridine blocked the channel from the intracellular face. This Ca(2+)-activated K+ channel in the muscle membrane of this acoelomate animal is similar in most respects to the maxi-K+ channels which have been described in a variety of cells from more highly evolved animals.

In vivo transport kinetics and distribution of taurocholate by rat ileum and jejunum

The transport kinetics and distribution of taurocholate (TC) from the ileum and jejunum were evaluated in anesthetized Sprague-Dawley rats. Uptake and transport kinetics were determined after simultaneous administration of equimolar solutions of [3H]taurocholic acid ([3H]TC) in the ileum and [24-14C]taurocholic acid ([14C]TC) in the jejunum of anesthetized rats. At TC concentrations between 0.3 and 15 mM, total ileal absorption exceeded jejunal absorption 15- to 25-fold. The apparent Km and Vmax for ileal absorption of TC were 5.6 mM and 65.5 nmol.min-1.cm-1, respectively. Tissue distribution studies following uptake from the ileum and jejunum were done with 75Se-labeled homocholic acid taurine (75Se-HCAT). In the ileum, 82% of the 75Se-HCAT removed from the lumen was found in the bile, 10.6% was found in the ileal wall, and 7.3% was found in the liver. In the jejunum, 24.1% was found in bile, 0.6% was found in the liver, and 75.3% remained in the jejunal wall. These data show that the ileum is much more efficient and better equipped than the jejunum to take up and transport TC at concentrations up to 15 mM.

Blood irradiation: rationale and technique

Upon request by the local American Red Cross, the Savannah Regional Center for Cancer Care irradiates whole blood or blood components to prevent post-transfusion graft-versus-host reaction in patients who have severely depressed immune systems. The rationale for blood irradiation, the total absorbed dose, the type of patients who require irradiated blood, and the regulations that apply to irradiated blood are presented. A method of irradiating blood using a linear accelerator is described.

Midazolam infusion and the benzodiazepine antagonist flumazenil for sedation of intensive care patients

ICU patients often require sedation. Midazolam (M), a new imidazobenzodiazepine, features rapid onset and rapid elimination time. Flumazenil (Ro 15-1788) is a new benzodiazepine antagonist. We studied the efficacy and safety of M by continuous infusion in 28 ICU patients: 16 post major surgery, and 12 medical patients, aged 20-77 years. M was administered as a loading dose of 0.05-0.15 mg/kg per min followed by continuous infusion of 0.05-0.1 mg/kg per h titrated to maintain patients asleep but arousable. M was administered for up to 14 days in doses of 1-15 mg/h and cumulative doses of up to 1915 mg. No untoward effects were noted except for slight decreases in blood pressure following the loading dose. ACTH challenge tests performed before and 24 h or more following the start of M showed no depression of adrenal responsivity. All patients meeting weaning criteria were weaned off mechanical ventilation while still on M. In 13 patients extubation was performed immediately after M was stopped, and flumazenil (0.38 +/- 0.27 mg, i.v.) given until full awakening. Patients remained awake yet calm. Vital signs remained stable after flumazenil. Midazolam by continuous infusion appears to be a safe and effective mode of sedation in ICU patients. Flumazenil may increase the flexibility and safety of this mode of sedation.

Evaluation of the hypolipidemic activity of xenalipin in experimental animals

Xenalipin (4'-trifluoromethyl-2-biphenylcarboxylic acid) is a chemically novel compound which has been found to be an effective hypolipidemic agent in two animal species. Significant reductions in serum cholesterol and triglycerides were observed in cholesterol-cholic acid-fed rats following oral doses of 10-30 mg/kg/day. Xenalipin was considerably more potent than clofibrate, nicotinic acid, and cholestyramine in the same model. Lipoprotein analysis showed that xenalipin reduced cholesterol and protein content in very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL). Triglycerides were reduced in VLDL and IDL. Xenalipin was also effective in reducing serum cholesterol and triglyceride concentrations in normocholesterolemic rats. In diet-induced hypercholesterolemic African green monkeys, xenalipin at oral doses of 15-60 mg/kg b.i.d. reduced serum LDL-cholesterol concentrations. These results suggest that xenalipin has a profile of activity which would be beneficial in therapy for hyperlipidemia.

Colostomy or ileostomy after colorectal anastomosis?: a randomised trial

Sixty one patients were entered in a randomised trial to compare transverse loop colostomy with loop ileostomy after a colorectal anastomosis thought to be at risk of dehiscence. Radiologically proven breakdown of the colorectal anastomosis occurred in 13% of these selected patients and most frequently in the colostomy group. Ileostomies functioned earlier than colostomies (P less than 0.001) but there was no other significant difference in outcome between the groups. In 52 patients intestinal continuity was restored by excision of the stoma within a month of construction with no difference in morbidity between the two groups. A loop ileostomy, closed as soon as the colorectal anastomosis has healed, is recommended as an alternative to transverse colostomy.

Specificity of the surface aminopeptidase in Moniliformis moniliformis (Acanthocephala)

The hydrolysis of various oligopeptides in solution by intact Moniliformis moniliformis was examined using paper chromatographic analysis of the incubation medium. In the presence of transport inhibitors, the respective peptide sub-units and/or amino acid residues accumulated in the bathing medium. Only peptides with serine, methionine, leucine or alanine at the NH2-terminal end of the peptide were hydrolysed. There was no hydrolysis when these amino acids were located internally or at the COOH-terminus indicating genuine aminopeptidase activity of the class, alpha-aminoacylpeptide hydrolase. Hydrolysis was negligible when the NH2-terminus was arginine, aspartic acid, glutamic acid, glycine, histidine, lysine, phenylalanine, proline, tryptophan, tyrosine, or valine. In separate experiments, mediated uptake of 0.1 mM 3H-leucine by the worms in 2 min was inhibited 100% by 5 mM unlabelled leucine or tri-serine, but only partially inhibited by 5 mM Ser-Gly (66%), 10 mM Ser-Gly (74%), 5 mM Leu-Leu (69%), 10 mM Leu-Leu (70%), 5 mM Leu-Gly (58%) or 5 mM Met-Met (69%). Because the inhibitions produced by 5 mM Leu-Leu plus 5 mM Met-Met (79%) or 5 mM Leu-Leu plus 5 mM Ser-Gly (76%) were not additive, a single enzyme is indicated. The name serine aminopeptidase is proposed because of its preference for serine.

A randomized trial to compare single with multiple phenol injection treatment for haemorrhoids

One hundred and twenty consecutive patients were entered into a randomized trial of single versus multiple phenol injection for the treatment of haemorrhoids. Follow-up at 3 and 12 months was available in 105 patients (56 in the single group and 49 in the multiple group). The results have shown that injection therapy, whether this be single or multiple, is an extremely effective form of therapy for patients with first or second degree haemorrhoids.

Determinants of visual attention in real-wound scenes

The present study examined the saliency of size, movement, and human content variables in visual selective attention. Ss named stimuli present in motion pictures of real world scenes or in animated cartoon controls during a 15-sec. exposure period. Regardless of the type of presentation that they saw, Ss tended to name large and/or moving stimuli more often than small and/or nonmoving stimuli. Also, small human stimuli were named more frequently than small nonhuman stimuli, while there were no differences between the frequencies with which large human and nonhuman stimuli were named. The order in which Ss named stimuli was not related to either the size, movement, or human content variables. Results are discussed in terms of the generalizability of the results of previous studies to conditions simulating the real world.