Apremilast effectively inhibits TNFα-induced vascular inflammation in human endothelial cells.

BACKGROUND: Patients with chronic inflammatory diseases (e.g. psoriasis and rheumatoid arthritis) are at increased risk for the development of atherosclerosis and cardiovascular diseases (CVD). Previous studies have suggested that phosphodiesterase 4 (PDE4) inhibitors possess anti-inflammatory properties. OBJECTIVES: Here we examined the effect of the PDE4 inhibitor apremilast, a well-established anti-psoriatic drug, on pro-inflammatory responses in TNFα-activated endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVEC) were treated with tumour necrosis factor-α (TNFα) in the presence or absence of apremilast. Expression levels of pro-inflammatory cytokines, chemokines and adhesion molecules were assessed by ELISA, western blot and RT-PCR. Effects of apremilast on adhesion and transendothelial migration (TEM) of THP-1 monocytic cells were analysed in transwell assays. RESULTS: Apremilast suppressed TNFα-induced expression and secretion of important endothelial and monocytic pro-inflammatory factors, including granulocyte-macrophage colony-stimulating factor (GM-CSF), C-X-C motif chemokine ligand 10 (CXCL10), chemokine (C-C motif) ligand 2 (CCL2), vascular cell adhesion molecule 1 (VCAM-1), E-selectin and matrix metalloproteinase-9 (MMP9). Functionally, apremilast reduced adhesion of THP-1 cells to activated HUVECs and TEM in response to TNFα. Mechanistically, apremilast suppressed activation of nuclear factor κB (NFκB) and mitogen-activated protein kinases (MAPK) signalling in activated HUVECs. Furthermore, inhibition of p38, C-Jun-N-terminale Kinase (JNK) and NFκB in activated HUVECs decreased expression of GM-CSF, VCAM-1 and E-selectin. Additionally, apremilast decreased IL-17A-induced secretion of IL-6 and CCL2. CONCLUSIONS: We demonstrate that apremilast has distinct anti-inflammatory effects in activated HUVECs, indicating that apremilast could have the therapeutic potential to prevent higher risk for CVD in patients with chronic inflammatory diseases.

Correction to: A pilot study of improved psychological distress with art therapy in patients with cancer undergoing chemotherapy.

An amendment to this paper has been published and can be accessed via the original article.

A pilot study of improved psychological distress with art therapy in patients with cancer undergoing chemotherapy.

BACKGROUND: Art therapy may improve the physical, mental, and emotional wellbeing of individuals for a variety of purposes. It remains understudied and underutilized in cancer care. We sought to determine the ability of a pilot art therapy program to improve the physical, mental, and emotional well-being of cancer patients. METHODS: Chemotherapy-recipients, age 18 years and older, diagnosed with any type or stage of cancer, were considered eligible to participate in this single arm, pilot study, using four visual analog scales (VAS) with visually-similar, 0-10 scale (10 being worst) thermometers assessing: 1) pain, 2) emotional distress, 3) depression, and 4) anxiety. Participants were asked to complete all 4 metrics, pre-treatment, post-treatment, and at 48-72 h follow-up, after an hour-long art therapy session. Primary endpoints included post-intervention changes from baseline in the 4 VAS metrics. RESULTS: Through a reasonable pilot sample (n = 50), 44% had breast cancer, 22% gastrointestinal cancers, 18% hematological malignancies, and 20% had other malignancies. A decrease in all VAS measures was noted immediately post-treatment but remained low only for pain and depression, not for emotional distress and anxiety upon follow up. There was a significant difference between the depression VAS scores of Hispanics (32%) compared to non-Hispanics (56%) (p = 0.009) at baseline. However, compared to non-Hispanics, Hispanics exhibited higher levels of depression after art therapy (P = 0.03) and during the follow-up intervals (p = 0.047). CONCLUSION: Art therapy improved the emotional distress, depression, anxiety and pain among all cancer patients, at all time points. While depression scores were higher pre-intervention for Hispanic patients, Hispanic patients were noted to derive a greater improvement in depression scores from art therapy over time, compared to non-Hispanics patients. Discovering simple, effective, therapeutic interventions, to aid in distress relief in cancer patients, is important for ensuring clinical efficacy of treatment and improved quality of life.

Safety and effectiveness of neuraminidase inhibitors for influenza treatment, prophylaxis, and outbreak control: a systematic review of systematic reviews and/or meta-analyses.

OBJECTIVES: To review evidence from systematic reviews and/or meta-analyses (SR/MAs) regarding neuraminidase inhibitor (NI) safety and effectiveness. METHODS: We conducted an SR of SR/MAs of randomized control and/or observational studies. We searched eight electronic databases for SR/MAs that examined the effectiveness or safety of NIs administered for influenza (i.e. influenza-like illness or lab-confirmed) treatment or prophylaxis. RESULTS: We identified 27 (0.7%) eligible SR/MAs of 3723 articles reviewed. NI (n = 2) or oseltamivir (n = 1) versus no treatment were consistently associated with a decrease in mortality odds among the hospitalized, general population (OR range 0.2 - 0.8). Oseltamivir versus no treatment was associated with a decrease in hospitalization and pneumonia risk/odds in 2/4 SR/MAs. Oseltamivir (n = 4) and zanamivir (n = 3) were consistently associated with a 0.5 - 1 day decrease in symptom duration. Oseltamivir (n = 4) or zanamivir (n = 4) versus no prophylaxis were consistently associated with a decrease in the odds/risk of symptomatic secondary transmission (OR/RR range 0.1 - 0.5). Oseltamivir versus no treatment was consistently associated with a 1.5- to 2.5-fold increase in the odds/risk of nausea (n = 4) and vomiting (n = 5). CONCLUSIONS: NI treatment is likely to be effective at reducing mortality among hospitalized patients, and symptom duration by up to 1 day in the general population. Oseltamivir or zanamivir prophylaxis are likely to be effective at reducing secondary symptomatic influenza transmission. Increased nausea and vomiting are likely associated with oseltamivir use. We recommend that decisions regarding NI use are made in consideration of potential adverse events, particularly for the general population at low risk of complications. Among hospitalized patients, NI administration seems warranted to reduce mortality risk.

Safety and effectiveness of neuraminidase inhibitors in situations of pandemic and/or novel/variant influenza: a systematic review of the literature, 2009-15.

Objectives: To review systematically the published literature evaluating neuraminidase inhibitor (NI) safety and effectiveness in situations of pandemic and novel/variant influenza. Methods: We searched six online databases using comprehensive search criteria for observational studies and randomized controlled trials investigating the effects of NI treatment, prophylaxis or outbreak control in patients of all ages. Results: Overall, 165 studies were included (95% observational), which were generally of low methodological quality due to lack of adjustment for confounding variables. In studies reporting adjusted estimates in general populations, NI treatment appeared likely to be effective against mortality (primarily if administered within 48 h of symptom onset) and potentially effective in reducing pneumonia. NIs appeared effective in reducing secondary transmission when indicated for prophylaxis. Limited, low-quality data suggest NIs are likely safe in general populations and may be safe in pregnant women and children. Data are scarce regarding safety of NIs in adults and high-risk individuals. Conclusions: Most included studies were observational, statistically underpowered and at high risk of reporting biased and/or confounded effect estimates. NI treatment appeared likely effective in reducing mortality (cause unspecified) and pneumonia in general populations, with increasing benefit when administered with 48 h of symptom onset. NI pre- or post-exposure prophylaxis is likely effective in reducing secondary transmission of influenza in a general population. Our evidence suggests NIs are likely safe to use in the general population; however, data for children and pregnant women are limited. Knowledge gaps persist in specific populations such as Aboriginals, high-risk individuals and the elderly.

HP-Xe to go: Storage and transportation of hyperpolarized (129)Xenon.

Recently the spin-lattice relaxation time T1 of hyperpolarized (HP)-(129)Xe was significantly improved by using uncoated and Rb-free storage vessels of GE180 glass. For these cells, a simple procedure was established to obtain reproducible wall relaxation times of about 18 h. Then the limiting relaxation mechanism in pure Xe is due to the coupling between the nuclear spins and the angular momentum of the Xe-Xe van-der-Waals-molecules. This mechanism can be significantly reduced by using different buffer gases of which CO2 was discovered to be the most efficient so far. From these values, it was estimated that for a 1:1 mixture of HP-Xe with CO2 a longitudinal relaxation time of about 7 h can be expected, sufficient to transport HP-Xe from a production to a remote application site. This prediction was verified for such a mixture at a total pressure of about 1 bar in a 10 cm glass cell showing a storage time of T1≈9 h (for T1(wall)=(34±9) h) which was transported inside a magnetic box over a distance of about 200 km by car.

The free lateral arm flap-a reliable option for reconstruction of the forearm and hand.

BACKGROUND: This retrospective study was performed to verify the advantages and disadvantages of the free lateral arm flap for defect reconstruction of the forearm and hand. PATIENTS AND METHODS: Between 2001 and 2010, 21 patients underwent defect coverage of the forearm and hand with the free lateral arm flap. The mean patient age was 48 years (17-78). The results concerning defect origin, flap size, pedicle length, operative time, revisions of the anastomoses or other complications, donor site morbidity, and length of hospital stay were evaluated. RESULTS: The majority of defects were caused by infections or chronic wounds. The defects were localized at the forearm in 6 cases and at the hand in 15 cases. The flap width ranged from 3 to 8 cm, and the length was from 5 to 20 cm. All flaps survived. Only in one case, a revision of the anastomosis was necessary. Primary closure of the donor site was possible in all patients. No complications occurred during the healing procedure. The majority of the patients were satisfied with the aesthetic result at the recipient site as well as at the donor site. CONCLUSION: The free lateral arm flap is a very reliable option for defect coverage at the forearm and hand for small and medium size defects. A satisfactory aesthetic appearance, an excellent tissue quality, and frequent primary donor site closure are great advantages for selecting this flap.

Peroxisome proliferator activated receptor-α agonists suppress transforming growth factor-α-induced matrix metalloproteinase-9 expression in human keratinocytes.

The peroxisome proliferator-activated receptors (PPARs), PPARα, PPARδ, and PPARγ, are nuclear ligand-activated transcription factors that are best known as regulators of glucose and lipid metabolism. PPARα agonists have been shown to have profound anti-inflammatory and antiproliferative effects on human keratinocytes, and are important for maintaining homeostasis of the skin. To better characterize the mechanisms underlying these phenomena, we analysed the effects of PPARα agonists on transforming growth factor (TGF)-α-induced expression of matrix metalloproteinase (MMP)-9. MMP-9 expression in keratinocytes has previously been linked to inflammatory skin diseases, regenerative skin mechanisms, and tumour development and metastasis. We found that PPARα agonists effectively inhibited TGF-α-induced MMP-9 expression in human keratinocytes via a post-transcriptional mechanism, revealing a novel and important aspect of the anti-inflammatory and anticarcinogenic action of these compounds.

[Applications of free lateral arm flap for hand and forearm defect reconstruction]. / Einsatzmöglichkeiten des freien lateralen Oberarmlappens zur Defektdeckung an Hand und Unterarm.

BACKGROUND: The purpose of this retrospective study was to verify the advantages and disadvantages of the free lateral arm flap for defect reconstruction of the forearm and hand. PATIENTS AND METHODS: The data of 21 patients who underwent defect coverage of the forearm and hand with the free lateral arm flap between 2002 and 2010 were analyzed. The mean patient age was 48 years (range 17-78 years). The results concerning defect origin, flap size, pedicle length, operative time, revision of the anastomosis or other complications, donor site morbidity and length of hospital stay were evaluated. RESULTS: In 6 cases the defect was on the forearm and in 15 on the hand. The majority of defects were infections or chronic wounds. The overage flap width ranged from 3 to 8 cm and the length from 5 to 20 cm. Revision of the anastomosis was only necessary in one case and flap survival rate was 100%. In all patients primary closure of the donor site was possible without complications during the healing procedure. CONCLUSION: The results underline the good reliability of the free lateral arm flap with a satisfactory aesthetic appearance excellent tissue quality and frequent primary donor site closure.

ProvenCare: quality improvement model for designing highly reliable care in cardiac surgery.

OBJECTIVE: To test whether an integrated delivery system could, through the application of process redesign methodology and reliability science, implement multiple evidence-based medical practices across the continuum of care for a specific surgical intervention and deliver these practices consistently. METHODS: The programme-ProvenCare--had three components: establishing best practices for elective coronary artery bypass graft (CABG) patients; assembling a multidisciplinary team to "hardwire" these best practices into everyday workflow; and implementing the programme with real-time data collection, feedback and focused redesign to reach high reliability. Surgeons reviewed all class I and IIa 2004 ACC/AHA guidelines for CABG surgery and translated them into 19 clinically applicable recommendations. A frontline multidisciplinary team "hardwired" these, resulting in 40 measurable process elements. Feedback of gaps in care was given and the process redesigned as needed. Clinical outcome data on consecutive elective CABG patients seen in the 12 months pre-intervention were then compared with a post-intervention group. RESULTS: Initially, 59% of patients received all 40 elements. At 3 months, compliance reached 100%, fell transiently to 86% and then reached 100% again, and was sustained for the remainder of the study. The overall trend in reliability was significant (p = 0.001). 30-day clinical outcomes showed improved trends in 8/9 measured areas (eg, patient readmissions to ICU decreased from 2.9% to 0.9% and blood products usage decreased from 23.4% to 16.2%). Operative mortality decreased to zero, but only likelihood of discharge was significant (p = 0.033). Frequency and length of readmissions fell, as did mean hospital charges. CONCLUSION: Frontline medical care providers, led by process design specialists, can successfully redesign episodic processes to consistently deliver evidence-based medicine, which may improve patient outcomes and reduce resource use.

Role of human CYP1A1 and NAT2 in 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine-induced mutagenicity and DNA adducts.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is carcinogenic in multiple organs and numerous species. Bioactivation of PhIP is initiated by PhIP N(2)-hydroxylation catalysed by cytochrome P450s. Following N-hydroxylation, O-acetylation catalysed by N-acetyltransferase 2 (NAT2) is considered a further possible activation pathway. Genetic polymorphisms in NAT2 may modify cancer risk following exposure. Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles were used to test the effect of CYP1A1 and NAT2 polymorphism on PhIP genotoxicity. Cells transfected with NAT2*4 had significantly higher levels of N-hydroxy-PhIP O-acetyltransferase (p = 0.0150) activity than cells transfected with NAT2*5B. Following PhIP treatment, CHO cell lines transfected with CYP1A1, CYP1A1/NAT2*4 and CYP1A1/NAT2*5B each showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase (hprt) mutagenesis not observed in untransfected CHO cells. dG-C8-PhIP was the primary DNA adduct formed and levels were dose dependent in transfected CHO cells in the order: CYP1A1 < CYP1A1 and NAT2*5B < CYP1A1 and NAT2*4, although levels did not differ significantly (p > 0.05) following one-way analysis of variance. These results strongly support activation of PhIP by CYP1A1 with little effect of human NAT2 genetic polymorphism on mutagenesis and DNA damage.

Absorption of short-chain fatty acids, sodium and water from the forestomach of camels.

In camelids the ventral parts of compartments 1 and 2 (C1/C2) and the total surface of compartment 3 of the forestomach are lined with tubular glands, whereas in ruminants the surface of the forestomach is composed entirely of stratified, squamous epithelium. Thus, differences in absorption rates between these foregut fermenters can be expected. In five camels C1/C2 was temporarily isolated, washed and filled with buffer solutions. Absorption of short-chain fatty acids (SCFA) and net absorption of sodium and water were estimated relative to Cr-ethylenediaminetetraacetic acid as a fluid marker. SCFA were extensively absorbed in the forestomach; clearance rates of SCFA with different chain lengths were equal. After lowering the pH of solutions SCFA absorption rates increased, but much less than the increase of the non-ionized fraction. Absorption of propionate was lower when acetate had been added. Findings suggest that most of the SCFA in camels are transported in the ionized form, most likely via an anion exchange mechanism. Net water absorption is closely related to net sodium absorption. Apparently water absorption results from an iso-osmotic process. Differences between absorption mechanisms of SCFA from the forestomach of camelids and ruminants are discussed.

Feed intake, forestomach fluid volume, dilution rate and mean retention of fluid in the forestomach during water deprivation and rehydration in camels (Camelus sp.).

Camels were deprived of water for 11 days. Before and during water deprivation and during rehydration changes in body weight, feed and water intake were measured. Using the liquid marker Cr-EDTA forestomach fluid volume, mean fluid retention and fluid dilution in the forestomach were estimated. At the eleventh day of water deprivation hay intake had decreased to only 9.6% of controls, dilution rates had decreased to 31%, mean retention time of fluid in the forestomach had increased to 189%. At the end of dehydration flow of saliva of 2 l/h mainly contributed to the still rather high dilution rates. Thereby buffering capacity and flow of fluid into the forestomach for microbial digestion as well as the outflow from the forestomach were maintained. At the beginning of rehydration camels drank 97 l within a few minutes, and animals thereby replaced all the water lost. Following this first huge water intake water is rapidly absorbed from the forestomach, and forestomach volume decreased again to dehydration values. At the third day of rehydration control values were reached again. Although feed intake decreased dramatically during water deprivation, functions of the forestomach can be maintained sufficiently mainly due to saliva inflow. This explains the mostly rapid recovery of camels when water is available again.

Chewing activities and oesophageal motility during feed intake, rumination and eructation in camels.

It was the aim of this study to characterize rumination behaviour, eructation and oesophageal motility in camels to identify similarities and differences between camels and domestic ruminants. Recordings were carried out in five camels fed on a hay-based diet. On an average, the duration of rumination, feeding and resting was 8.3, 5.6 and 10.1 h per 24 h, respectively. Rumination activity peaked in the morning between 9:00 and 11:00 and in the night between 02:00 and 04:00 a.m. During rumination periods, on an average 67 boluses were regurgitated per hour. Each bolus was chewed for an average of 45 s with 68 chews per min. The pause between two rumination cycles lasted on an average 9 s. Hay intake took 61 min/kg dry matter (DM), rumination lasted 71 min/kg DM of hay consumed. The regurgitation of a bolus started with a contraction of cranial compartment 1 (C 1) during a B-sequence, followed by a deep inspiration with closed glottis. Digesta enters the oesophagus, and an antiperistaltic wave transported the bolus orally. Eructation starts with a contraction of the caudal C1 during a B-sequence when the cranial C1 is relaxed. After entering the oesophagus, a rapid antiperistaltic wave transports the gas orally. Results revealed that the parameter values obtained in the camels were remarkably similar to those in domestic ruminants despite profound morphological differences and different patterns of forestomach motility.

The maximum attainable body size of herbivorous mammals: morphophysiological constraints on foregut, and adaptations of hindgut fermenters.

An oft-cited nutritional advantage of large body size is that larger animals have lower relative energy requirements and that, due to their increased gastrointestinal tract (GIT) capacity, they achieve longer ingesta passage rates, which allows them to use forage of lower quality. However, the fermentation of plant material cannot be optimized endlessly; there is a time when plant fibre is totally fermented, and another when energy losses due to methanogenic bacteria become punitive. Therefore, very large herbivores would need to evolve adaptations for a comparative acceleration of ingesta passage. To our knowledge, this phenomenon has not been emphasized in the literature to date. We propose that, among the extant herbivores, elephants, with their comparatively fast passage rate and low digestibility coefficients, are indicators of a trend that allowed even larger hindgut fermenting mammals to exist. The limited existing anatomical data on large hindgut fermenters suggests that both a relative shortening of the GIT, an increase in GIT diameter, and a reduced caecum might contribute to relatively faster ingesta passage; however, more anatomical data is needed to verify these hypotheses. The digestive physiology of large foregut fermenters presents a unique problem: ruminant-and nonruminant-forestomachs were designed to delay ingesta passage, and they limit food intake as a side effect. Therefore, with increasing body size and increasing absolute energy requirements, their relative capacity has to increase in order to compensate for this intake limitation. It seems that the foregut fermenting ungulates did not evolve species in which the intake-limiting effect of the foregut could be reduced, e.g. by special bypass structures, and hence this digestive model imposed an intrinsic body size limit. This limit will be lower the more the natural diet enhances the ingesta retention and hence the intake-limiting effect. Therefore, due to the mechanical characteristics of grass, grazing ruminants cannot become as big as the largest browsing ruminant. Ruminants are not absent from the very large body size classes because their digestive physiology offers no particular advantage, but because their digestive physiology itself intrinsically imposes a body size limit. We suggest that the decreasing ability for colonic water absorption in large grazing ruminants and the largest extant foregut fermenter, the hippopotamus, are an indication of this limit, and are the outcome of the competition of organs for the available space within the abdominal cavity. Our hypotheses are supported by the fossil record on extinct ruminant/tylopod species which did not, with the possible exception of the Sivatheriinae, surpass extant species in maximum body size. In contrast to foregut fermentation, the GIT design of hindgut fermenters allows adaptations for relative passage acceleration, which explains why very large extinct mammalian herbivores are thought to have been hindgut fermenters.

Noninvasive monitoring of adrenocortical activity in roe deer (Capreolus capreolus) by measurement of fecal cortisol metabolites.

A method for measuring glucocorticoids noninvasively in feces of roe deer was established and validated. The enzyme immunoassay (EIA) measures 11,17-dioxoandrostanes (11,17-DOA), a group of cortisol metabolites. Such measurement avoids blood sampling and reflects a dampened pattern of diurnal glucocorticoid secretion, providing an integrated measure of adrenocortical activity. After high-performance liquid chromatography, the presence of at least three different immunoreactive 11,17-DOA in the feces of roe deer was demonstrated. The physiological relevance of these fecal cortisol metabolites to adrenocortical activity was evaluated with an adrenocorticotropic hormone challenge test: cortisol metabolite concentrations exceeded pretreatment levels (31-78 ng/g) up to 13-fold (183-944 ng/g) within 8-23 h. Starting from basal levels between 13 and 71 ng/g, a suppression of adrenocortical activity after dexamethasone administration, indicated by metabolite levels close to the detection limit, was obtained 36-81 h after treatment, whereas unmetabolized dexamethasone was detectable in feces 12 h after its injection. Fecal glucocorticoid metabolite assessment via EIA is therefore of use in the monitoring of adrenocortical activity in roe deer. In a second experiment, capture, veterinary treatment, and transportation of animals were used as experimental stresses. This resulted in a 7.5-fold increase of fecal metabolites (1200 +/- 880 ng/g, mean +/- SD) compared to baseline concentrations. The administration of a long-acting tranquilizer (LAT), designed to minimize the physiological stress response, 2 days prior to a similar stress event led to a reduced stress response, resulting in only a 4-fold increase of fecal metabolites (650 +/- 280 ng/g; mean +/- SD). Therefore, LATs should be further investigated for their effectiveness in reducing stress responses in zoo and wild animals, e.g., when translocations are necessary.

Functional characterization of nucleotide polymorphisms in the coding region of N-acetyltransferase 1.

N-acetyltransferase 1 (NAT1) catalyses the activation and/or deactivation of aromatic and heterocyclic amine carcinogens. A genetic polymorphism in NAT1 is associated with an increased risk of various cancers and drug toxicities, but epidemiological investigations are severely compromised by a poor understanding of the relationship between NAT1 genotype and phenotype. Human reference NAT1*4 and 12 known human NAT1 allelic variants possessing nucleotide polymorphisms in the NAT1 coding region were cloned and expressed in yeast (Schizosaccharomyces pombe). Large reductions in N- and O-acetyltransferase catalytic activities were observed for recombinant NAT1 allozymes encoded by NAT1*14B, NAT1*15, NAT1*17, NAT1*19 and NAT1*22. Each of these alleles exhibited NAT1 protein expression levels below the limit of detection as measured by Western blot. No differences between high and low activity NAT1 alleles were observed in relative mRNA expression or relative transformation efficiency. The recombinant NAT1 17 and NAT1 22 allozymes showed reduced intrinsic stability when compared with NAT1 4. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) N-acetylation was not catalysed by any of the NAT1 allozymes. Large differences in the metabolic activation via O-acetylation of 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP) were noted for NAT1 allelic variants. The results of these studies suggest an important role for the NAT1 genetic polymorphism in metabolism of aromatic and heterocyclic amine carcinogens. Furthermore, these results suggest that low NAT1 phenotype results from NAT1 allelic variants that encode reduced expression of NAT1 and/or less-stable NAT1 protein.

Functional characterization of human N-acetyltransferase 2 (NAT2) single nucleotide polymorphisms.

N-Acetyltransferase 2 (NAT2) catalyses the activation and/or deactivation of a variety of aromatic amine drugs and carcinogens. Polymorphisms in the N-acetyltransferase 2 (NAT2) gene have been associated with a variety of drug-induced toxicities, as well as cancer in various tissues. Eleven single nucleotide polymorphisms (SNPs) have been identified in the NAT2 coding region, but the specific effects of each of these SNPs on expression of NAT2 protein and N-acetyltransferase enzymatic activity are poorly understood. To investigate the functional consequences of SNPs in the NAT2 coding region, reference NAT2*4 and NAT2 variant alleles possessing one of the 11 SNPs in the NAT2 coding region were cloned and expressed in yeast (Schizosaccharomyces pombe). Reductions in catalytic activity for the N-acetylation of a sulfonamide drug (sulfamethazine) and an aromatic amine carcinogen (2-aminofluorene) were observed for NAT2 variants possessing G191A (R64Q), T341C (I114T), A434C (E145P), G590A (R197Q), A845C (K282T) or G857A (G286T). Reductions in expression of NAT2 immunoreactive protein were observed for NAT2 variants possessing T341C, A434C or G590A. Reductions in protein stability were noted for NAT2 variants possessing G191A, A845C, G857A or, to some extent, G590A. No significant differences in mRNA expression or transformation efficiency were observed among any of the NAT2 alleles. These results suggest two mechanisms for slow acetylator phenotype(s) and more clearly define the effects of individual SNPs on human NAT2 expression, stability and catalytic activity.

Metabolic evidence of a 'rumen bypass' or a 'ruminal escape' of nutrients in roe deer (Capreolus capreolus).

As short chain fatty acids produced in the forestomach are insufficient to satisfy the energy requirements of the concentrate selecting roe deer (Capreolus capreolus), it is proposed that these animals may have other mechanisms to avoid energy losses due to microbial fermentation. Nutrients bypassing down the ventricular groove (rumen bypass) or ruminal escape of unfermented or partially fermented nutrients may be two alternatives. As metabolic evidence for incomplete fermentation in the forestomach we investigated: (1) the abundance of the sodium-dependent glucose co-transporter (SGLT1) in the duodenum; (2) enzyme activities of maltase, saccharase and alpha-amylase in duodenal and pancreatic tissue; and (3) the proportion of essential, polyunsaturated fatty acids in depot fat samples from ruminants of different feeding type and--for comparison--from animals with a simple stomach. The high abundance of SGLT1, high enzyme activity and the high proportion of polyunsaturated fatty acids in the concentrate selecting ruminants support the hypothesis of rumen bypass or ruminal escape of nutrients in roe deer and reflect differences in nutrient utilization by ruminants that belong to different feeding types.

DNA adduct levels and absence of tumors in female rapid and slow acetylator congenic hamsters administered the rat mammary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine.

N-acetyltransferases (EC 2.3.1.5) catalyze O-acetylation of heterocyclic amine carcinogens to DNA-reactive electrophiles that bind and mutate DNA. An acetylation polymorphism exists in humans and Syrian hamsters regulated by N-acetyltransferase-2 (NAT2) genotype. Some human epidemiological studies suggest a role for NAT2 phenotype in predisposition to cancers related to heterocyclic amine exposures, including breast cancer. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine carcinogen prevalent in the human environment and induces a high incidence of mammary tumors in female rats. PhIP-induced carcinogenesis was examined in female rapid and slow acetylator Syrian hamsters congenic at the NAT2 locus. In both rapid and slow acetylators, PhIP-DNA adduct levels were highest in pancreas, lower in heart, small intestine, and colon, and lowest in mammary gland and liver. Metabolic activation of N-hydroxy-PhIP by O-acetyltransferase was highest in mammary epithelial cells, lower in liver and colon, and lowest in pancreas. Metabolic activation of N-hydroxy-PhIP by O-sulfotransferase was low in liver and colon and below the limit of detection in mammary epithelial cells and pancreas. Unlike the rat, PhIP did not induce breast or any other tumors in female rapid and slow acetylator congenic hamsters administered high-dose PhIP (10 doses of 75 mg/kg) and a high-fat diet.