Physiological condition of bank voles (Myodes glareolus) during the increase and decline phases of the population cycle.

The dynamics of animal populations are greatly influenced by interactions with their natural enemies and food resources. However, quantifying the relative effects of these factors on demographic rates remains a perpetual challenge for animal population ecology. Food scarcity is assumed to limit the growth and to initiate the decline of cyclic herbivore populations, but this has not been verified with physiological health indices. We hypothesized that individuals in declining populations would exhibit signs of malnutrition-induced deterioration of physiological condition. We evaluated the association of body condition with population cycle phase in bank voles (Myodes glareolus) during the increase and decline phases of a population cycle. The bank voles had lower body masses, condition indices and absolute masses of particular organs during the decline. Simultaneously, they had lower femoral masses, mineral contents and densities. Hemoglobin and hematocrit values and several parameters known to respond to food deprivation were unaffected by the population phase. There were no signs of lymphopenia, eosinophilia, granulocytosis or monocytosis. Erythrocyte counts were higher and plasma total protein levels and tissue proportions of essential polyunsaturated fatty acids lower in the population decline. Ectoparasite load was lower and adrenal gland masses or catecholamine concentrations did not suggest higher stress levels. Food availability seems to limit the size of voles during the decline but they can adapt to the prevailing conditions without clear deleterious health effects. This highlights the importance of quantifying individual health state when evaluating the effects of complex trophic interactions on the dynamics of wild animal populations.

Physiological adaptations to prolonged fasting in the overwintering striped skunk (Mephitis mephitis).

Wintertime physiology of captive striped skunks (Mephitis mephitis) in response to cold ambient temperature (Ta) and fasting was investigated with body temperature (Tb) and activity recordings and analyses of hematology, plasma biochemistry and tissue fatty acids (FA). After 105 days of food deprivation, the skunks were in phase II of fasting indicated by the elevated plasma nonesterified FA and glycerol but no accumulation of nitrogen end products. Shorter-chain saturated and monounsaturated FA together with C18-20 n-3 polyunsaturated FA were preferentially mobilized. Individual amino acids responded to fasting in a complex manner, while essential and nonessential amino acid sums remained stable. Increases in hemoglobin and hematocrit suggested dehydration. The activity levels were lower in mid-January-early March, and the activity bouts were mostly displayed between 17:00-23:00 h. Daily torpor was observed in two females with 29 and 46 bouts. The deepest torpor (Tb<31 °C) occurred between dawn and early afternoon and lasted for 3.3 ± 0.18 h. The average minimum Tb was 29.2 ± 0.15 °C and the lowest recorded Tb was 25.8 °C. There was significant relation between the average 24-h Tb and Ta. Increases in wintertime Ta, as predicted by climate change scenarios, could influence torpor patterns in the species.

Fatty acid mobilization in voles--model species for rapid fasting response and fatty liver.

Factors regulating fatty acid (FA) composition of small herbivores are poorly known. Because of the fast response to food deprivation, the tissue FA profiles of voles could be rapidly modified. The selectivity of incorporating dietary FA into tissue total lipids and mobilizing tissue FA was examined in two Microtus vole species either fed or fasted for 12-18 h. The FA composition of the tissues reflected the dietary lipids, but FA were selectively incorporated depending on their structure. The FA profiles of white and brown adipose tissues were different and contained more saturated and monounsaturated FA and less polyunsaturated FA (PUFA) than the diet. The essential PUFA precursors with smaller tissue percentages were likely converted into longer-chain derivatives for structural lipids. The FA composition of the vole tissues was selectively modified by food deprivation. The preferences for retention or loss were tissue-specific and related to the FA structure. Livers displayed steatosis with characteristic accumulation of triacylglycerols, while FA prevalent in membrane phospholipids decreased in proportion. Hepatic FA could be partly derived from lipids hydrolyzed in fat depots. The FA profiles of the vole tissues reflect the dietary lipids and are rapidly and selectively modified by food deprivation.

High-throughput analysis of testosterone in serum samples by on-line solid phase extraction liquid chromatography-tandem mass spectrometry.

BACKGROUND: Liquid chromatography tandem-mass spectrometer (LC-MS/MS) techniques are more and more common in the measurement of testosterone concentrations in biological samples. However, LC-MS/MS methods are more laborious than streamlined automated immunochemistry methods because of the need for tedious pre-purification of the sample before the mass spectrometric analysis. We therefore developed a robust and rapid sample clean-up method to improve the throughput of the whole LC-MS/MS analysis procedure by applying an automated on-line solid-phase extraction (SPE) technique instead of the still widely used conventional liquid-liquid extraction. METHODS: Testosterone was purified by the on-line SPE-column-switching technique after rapid precipitation of serum samples by zinc sulphate/internal standard solution before LC-MS/MS analysis. The results were compared with those of our previous routine LC-MS/MS method using liquid-liquid extraction with tert-butyl methyl ether for the pre-purification of the samples. RESULTS: The tested on-line SPE-LC-MS/MS method reached the specifications of the previous method with liquid-liquid extraction. The precision of the new method was notably better, especially in the lower concentration range, than with the former method; the total variation was below 10% in the whole quantitation range of 0.25-35 nmol/L. The new method liberates more than 50% of hands-on time of laboratory technicians as well as expensive instrument time for other applications compared with the older method. CONCLUSIONS: The on-line SPE-pre-purification technique tested in long-term use offers a rapid and reliable technique in the LC-MS/MS analysis of serum testosterone and is a valuable tool in the improvement of efficiency in the laborious steroid analytics.

Adaptation of the Diazyme Direct Enzymatic HbA1c Assay for a microplate reader at room temperature.

BACKGROUND: Measurement of hemoglobin A(1c) (HbA(1c)) is a key diagnostic criterion and a key parameter for the follow-up of the treatment of diabetes mellitus. Typically, immunochemical assays of HbA(1c) are performed in clinical chemistry analyzers. In this study, we applied the HbA(1c) assay on a microplate reader at room temperature. METHODS: HbA(1c) samples were measured using the Direct Enzymatic HbA(1c) Assay from Diazyme Laboratories (Poway, CA, USA) using a Plate Chameleon Microplate Reader (Hidex Co., Turku, Finland) according to the manufacturer's protocol and a modification of the method to room temperature. The Tosoh G7 HPLC method for HbA(1c) (Tosoh Co., Tokyo, Japan) was used as a comparative method. RESULTS: There was good correlation of HbA(1c) results when the assay was performed at room temperature (+22°C) compared with that at +37°C (r=0.987). The modified method was linear over the HbA(1c) range 4%-14%. Analysis of HbA(1c) results from 50 blood samples by the modified method showed good agreement with the HPLC method (r=0.990). CONCLUSIONS: The modified Diazyme Direct Enzymatic HbA(1c) Assay™ appears to work as good at +22°C as that performed according to manufacturer's protocol at +37°C.

Electrocardiographic alterations during hyperinsulinemic hypoglycemia in healthy subjects.

BACKGROUND: We evaluated the arrhythmogenic potential of hypoglycemia by studying electrocardiographic (ECG) changes in response to hyperinsulinemic hypoglycemia and associated sympathoadrenal counterregulatory responses in healthy subjects. METHODS: The study population consisted of 18 subjects, aged 30-40 years. Five-minute ECG recordings and blood samplings were performed at baseline and during the euglycemic and hypoglycemic hyperinsulinemic clamp studies. PR, QT, and QTc intervals of electrocardiogram and ECG morphology were assessed from signal-averaged ECG. RESULTS: Although cardiac beat interval remained unchanged, PR interval decreased (P < 0.01) and QTc interval (P < 0.001) increased in response to hyperinsulinemic hypoglycemia. Concomitant morphological alterations consisted of slight increases in R-wave amplitude and area (P < 0.01 for both), significant decreases in T-wave amplitude and area (P < 0.001 for both), and moderate ST depression (P < 0.001). Counterregulatory norepinephrine response correlated with amplification of the R wave (r =-0.620, P < 0.05) and epinephrine response correlated with flattening of the T wave (r =-0.508, P < 0.05). CONCLUSIONS: Hyperinsulinemic hypoglycemia with consequent sympathetic humoral activation is associated with several ECG alterations in atrioventricular conduction, ventricular depolarization, and ventricular repolarization. Such alterations in cardiac electrical function may be of importance in provoking severe arrhythmias and "dead-in-bed" syndrome in diabetic patients with unrecognized hypoglycemic episodes.

Effect of aerobic fitness on the physiological stress responses at work.

OBJECTIVES: The aim of the present study was to examine the effects of aerobic fitness on physiological stress responses experienced by teachers during working hours. MATERIALS AND METHODS: Twenty-six healthy female and male teachers aged 33-62 years participated in the study. The ratings of perceived stress visual analogue scale (VAS), and the measurement of physiological responses (norepinephrine, epinephrine, cortisol, diastolic and systolic blood pressure, heart rate (HR), and trapezius muscle activity by electromyography (EMG), were determined. Predicted maximal oxygen uptake (VO(2)max) was measured using the submaximal bicycle ergometer test. The predicted VO(2)max was standardized for age using residuals of linear regression analyses. RESULTS: Static EMG activity, HR and VAS were associated with aerobic fitness in teachers. CONCLUSIONS: The results suggest that a higher level of aerobic fitness may reduce muscle tension, HR and perceived work stress in teachers.

Comparison of HPLC method and commercial ELISA assay for asymmetric dimethylarginine (ADMA) determination in human serum.

The performance of a new ELISA assay kit (DLD Diagnostika GmbH, Hamburg, Germany) for the determination of asymmetric dimethylarginine (ADMA) was evaluated against a reversed phase HPLC method. ADMA concentrations of 55 serum samples were measured with both methods. The intra-assay CV for ADMA-ELISA was 19% (n=10). Inter-assay CVs for ADMA-ELISA were 9% for kit control 1 (0.410+/-0.037 microM) and 14% for kit control 2 (1.174+/-0.165 microM). The intra- and inter-assay CVs for HPLC assay for ADMA were 2.5% (0.586+/-0.015 microM) and 4.2% (0.664+/-0.028 microM), respectively. There was no correlation between these two methods (R(2)=0.0972). The effect of storage conditions of the samples on ADMA concentrations was investigated by HPLC. ADMA concentration was stable after four freezing and thawing cycles. Overall, the HPLC method offered better sensitivity, selectivity and, very importantly, simultaneous determination of ADMA, SDMA, l-homoarginine and l-arginine.

Psychophysiological stress in high school teachers.

OBJECTIVES: The aim of this study was to follow psychophysiological stress over a year with four repeated measurements in full-time employed high school teachers and to compare their results with those obtained in the part-time retired teachers, gardeners and rescue workers. MATERIALS AND METHODS: The subjects consisted of 17 (10 females, 7 males) full-time and 9 part-time employed teachers (7 females and 2 males) in three high schools, 12 female gardeners and 13 male rescue workers. The data on job conditions, well-being, and psychosomatic symptoms were obtained by a questionnaire. The perceived stress was recorded using a visual analogue scale. The neuroendocrine reactivity was assessed by determining the diurnal urine excretion of epinephrine and norepinephrine. Electromyography of the trapezius muscle was recorded during working days in all subjects and in full-time teachers on one day in the holiday season. Blood pressure and heart rate were measured in the morning and in the afternoon. RESULTS: Psychophysiological stress in the full-time employed teachers was at similar levels on all three working days in December, March and November. Recovery from psychophysiological stress of working period was observed on summer holidays. Blood pressure, static muscle tension, perceived strain, psychosomatic symptoms and epinephrine level decreased significantly during the summer holidays as compared to the working days. The full-time employed teachers reported more perceived stress and psychosomatic symptoms than the part-time retired teachers or gardeners and rescue workers. Also static muscle activity was higher in full-time teachers than in rescue workers on the working days. CONCLUSIONS: More emphasis should be given to prevent psychophysiolocigal stress among teachers as well as to develop stress coping methods, and part-time working systems to facilitate work ability of aging teachers.

Fatty acid composition in tissues of the farmed Siberian sturgeon (Acipenser baerii).

The fatty acid (FA) compositions of the diet and diverse tissues of the farmed Siberian sturgeon (Acipenser baerii) were analyzed in detail to assess their nutritional quality. Twelve male fish were sampled for muscle, fat, liver, brain, gill, kidney and gonad and the tissue FA measured by gas-liquid chromatography. The FA profile of the diet diverged from the FA signatures of the tissues, where the sturgeons accumulated particular highly-unsaturated FA (HUFA). They were probably derived from the diet but, as previous studies have shown that fish can also have desaturase enzymes, endogenous synthesis of these FA cannot be excluded. The sturgeon muscle tissue contained HUFA in proportions comparable to those of other fish species that are considered good sources of n-3 polyunsaturated FA. The indices of atherogenicity and thrombogenicity were also within the values considered to be health-promoting.

Fatty acid modifications during autumnal cold-hardening in an obligatory ectoparasite, the deer ked (Lipoptena cervi).

Poikilothermic organisms often modify their tissue fatty acids (FA) in response to cold exposure by increased unsaturation. In insects, this has been found to be accompanied by increases in the activities or mRNA expression of desaturase enzymes. In the present study, the FA composition of an obligatory ectoparasite, the deer ked (Lipoptena cervi), was analyzed in August-November. In addition to studying the general FA profile of the species, the possible contribution of FA to autumnal cold-hardening was examined. The FA composition of the deer ked imago was relatively similar to previously studied dipteran species, with high percentages of monounsaturated FA (especially 18:1n-9 and 16:1n-7) and 16:0. The individuals caught later in autumn had significantly higher values for the ratio of unsaturated to saturated FA and, regarding individual FA, the percentages of 18:1n-9, 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 were higher but those of 16:0 and 16:1n-7 lower than in August. Potential selective use of particular FA for energy could not account for the large increase in the levels of polyunsaturated FA (PUFA). The observed increased degree of FA unsaturation may have resulted from cold-induced desaturation, as observed previously in other species, or increased survival of the keds with relatively large PUFA contents. The PUFA with low melting points probably allow lipid membranes to maintain sufficient fluidity required to maintain protein functions at low ambient temperatures.

Manifestations of fasting-induced fatty liver and rapid recovery from steatosis in voles fed lard or flaxseed oil lipids.

Long-chain n-3 polyunsaturated fatty acids (PUFA) can have beneficial effects against fat deposition, cardiovascular diseases, and liver steatosis. We investigated how diets based on lard (predominantly saturated and monounsaturated fatty acids) or flaxseed oil (rich in 18:3n-3) affect liver fat-% and fatty acid profiles of tundra voles (Microtus oeconomus). We also studied potential participation of hyaluronan (HA) in the pathology of fatty liver and whether the development and recovery of fasting-induced steatosis are influenced by n-3 PUFA. The dietary fatty acid composition was manifested in the liver fatty acid signatures. Fasting for 18 h induced macrovesicular steatosis and the liver fat-% increased to 22% independent of the preceding diet. Fasting-induced steatosis did not involve inflammation or connective tissue activation indicated by the absence of both leukocyte accumulation and increased HA. Food deprivation modified the liver fatty acid signatures to resemble more closely the diets. Fasting reduced the proportions of long-chain n-3 PUFA in both dietary regimes and n-3/n-6 PUFA ratios in the lard-fed voles. Decreases in long-chain n-3 PUFA may promote lipid accumulation by modulating the expression of lipid-metabolizing genes. Dietary 18:3n-3 did not prevent the development or attenuate the manifestation of steatosis in the fasted voles or promote the recovery.

The analgesic concentration of oxycodone with co-administration of paracetamol -- a dose-finding study in adult patients undergoing laparoscopic cholecystectomy.

We have previously shown that paracetamol has an opioid-sparing effect in tonsillectomy, and now, we evaluated the analgesic efficacy of paracetamol i.v. in early post-operative pain after laparoscopic cholecystectomy (LCC). Twenty-four patients with LCC were randomized to receive paracetamol i.v. 1 g (group 1) or 2 g (group 2) at the end of surgery. All patients were provided 0.1 mg/kg of oxycodone i.v. 15 min. before the end of surgery. At the recovery room when the wound pain at rest was ≥ 3/10 and/or ≥ 5/10 during the wound compression, plasma sample was taken for the determination of oxycodone (minimum effective concentration, MEC), its metabolites and paracetamol. After that the patients were titrated with further doses of oxycodone i.v. to wound pain < 3/10 at rest and < 5/10 during wound compression, plasma sample was taken for the determination of minimum effective analgesic concentration (MEAC) of oxycodone. The total oxycodone dose needed for pain relief was similar, about 0.3 mg/kg (range 0.2-0.5), in both groups (p = 0.80). At the onset of pain, P-oxycodone (MEC) was similar in both groups, 25 ng/ml (19-32) in group 1 and 24 ng/ml (16-34) in group 2. The pain relief (MEAC) was achieved in group 1 with P-oxycodone 70 ng/ml (30-131) and in group 2 with 62 ng/ml (36-100) (p = 0.48). In conclusion, in the early-phase after LCC, there was no significant difference between the effect of paracetamol doses of 1 g and 2 g i.v. on the need of i.v. oxycodone.

Acute effects of ethanol on the transfer of nicotine and two dietary carcinogens in human placental perfusion.

Many mothers use, against instructions, alcohol during pregnancy. Simultaneously mothers are exposed to a wide range of other environmental chemicals. These chemicals may also harm the developing fetus, because almost all toxic compounds can go through human placenta. Toxicokinetic effects of ethanol on the transfer of other environmental compounds through human placenta have not been studied before. It is known that ethanol has lytic properties and increases the permeability and fluidity of cell membranes. We studied the effects of ethanol on the transfer of three different environmental toxins: nicotine, PhIP (2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine) and NDMA (N-nitrosodimethylamine) in placental perfusion. We tested in human breast cancer adenocarcinoma cell line MCF-7 whether ethanol affects ABCG2/BCRP, which is also the major transporter in human placenta. We found that the transfer of ethanol is comparable to that of antipyrine, which points to passive diffusion as the transfer mechanism. Unexpectedly, ethanol had no statistically significant effect on the transfer of the other studied compounds. Neither did ethanol inhibit the function of ABCG2/BCRP. These experiments represent only the effects of acute exposure to ethanol and chronic exposure remains to be studied.

Paracetamol (acetaminophen) penetrates readily into the cerebrospinal fluid of children after intravenous administration.

INTRODUCTION: The main action of paracetamol (acetaminophen) is presumed to be in the central nervous system. The central nervous system penetration of paracetamol has been described in children with intracranial pathologies but not in children with an intact blood-brain barrier. OBJECTIVE: We investigated the cerebrospinal fluid penetration of paracetamol in 32 healthy children, aged 3 months to 12 years, who were undergoing surgery in the lower body using spinal anesthesia. MATERIALS AND METHODS: In this open-label prospective study, children were given a single intravenous injection of paracetamol (15 mg/kg). Cerebrospinal fluid and venous blood samples were obtained between 5 minutes and 5 hours after injection. Paracetamol concentrations were determined from the cerebrospinal fluid and plasma by using a fluorescence polarization immunoassay. RESULTS: Paracetamol was detected in cerebrospinal fluid from the earliest sample at 5 minutes, although in this sample paracetamol concentration was below the limit of quantification of 1.0 mg/L. Subsequent paracetamol concentrations in cerebrospinal fluid ranged between 1.3 and 18 mg/L (median: 7.2 mg/L), plasma concentrations ranged between 2.4 and 33 mg/L, and cerebrospinal fluid/plasma ratios ranged between 0.06 and 2.0. The highest CSF paracetamol concentration was detected at 57 minutes. CONCLUSIONS: Paracetamol permeates readily into the cerebrospinal fluid of children. This fast and extensive transfer enables the rapid central analgesic and antipyretic action of intravenous paracetamol.

Disialotransferrin, determined by capillary electrophoresis, is an accurate biomarker for alcoholic cause of acute pancreatitis.

OBJECTIVES: Serum disialotransferrin is a specific marker of heavy alcohol consumption. We tested its accuracy and probability in detecting alcoholic cause of acute pancreatitis (AP). METHODS: Blood samples from 271 consecutive AP patients, admitted to the Helsinki University Central Hospital emergency unit, were analyzed. RESULTS: The median (range) disialotransferrin value was significantly higher (P = 0.001) in AP patients with alcoholic (n = 172) 1.6% (0.3%-14.4) than with biliary (n = 60) 0.7% (0.3%-1.3%) or other causes (n = 39) 0.8% (0.3%-4.1%). In receiver operating curve analysis, disialotransferrin, as a single analyte, was significantly (P = 0.001-0.0001) more accurate (area under the curve [AUC], 0.88; 95% confidence interval [CI], 0.84-0.92) in detecting alcoholic AP as compared with glutamyl transferase (AUC, 0.51; 95% CI, 0.45-0.57), aspartate aminotransferase (AUC, 0.57; 95% CI, 0.51-0.63), alanine aminotransferase (AUC, 0.63; 95% CI, 0.57-0.69), erythrocyte mean cell volume (AUC, 0.72; 95% CI, 0.67-0.78), amylase (AUC, 0.74; 95% CI, 0.67-0.78), C-reactive protein (AUC, 0.65; 95% CI, 0.59-0.71), and bilirubin (AUC, 0.55; 95% CI, 0.49-0.62). At a disialotransferrin cutoff of 1.2%, giving an 8% false-positive rate, the positive likelihood ratio was 8.47. Thus, a positive disialotransferrin test result, performed within 24 hours of admission, increased the probability of alcoholic AP from pretest 64% to posttest 94%. CONCLUSIONS: Disialotransferrin, determined by capillary electrophoresis, is accurate, simple, and a rapid single biomarker of the alcoholic cause of AP.