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Biomedical subjects

M Ericson

Publications and source records attributed to M Ericson.

54 records · Page 3Linked to original sources
PubMed1997

Pronounced resting bradycardia in male elite runners is associated with high heart rate variability.

Forty-eight hour Holter monitoring was undertaken of 16 male elite middle- and long-distance runners, age 25 +/- 3 years, with peak oxygen uptake 4.83 +/- 0.43 1 O2/min or 73.0 +/- 3.9 ml O2/kg/min. The athletes had pronounced bradycardia during the night-time, with heart rate calculated from four RR intervals < 30 beats/min in five runners. Twelve of 16 runners had RR intervals > 2 s. Of those, 10 runners had sinus pauses exceeding 2 s, the longest being 3.06 s. Three runners had AV block II, two with Mobitz type 1, and one with both Mobitz type 1 and 2. Autonomic function was estimated by time domain and power spectral analysis of heart rate variability. The runners were compared with a control group of 13 sedentary or moderately active subjects. The runners had a mean of 14 b.p.m. lower heart rate at night than the controls. The runners had higher heart rate variability in all spectral bands. In the time domain pNN50 and rMSSD, which are considered to reflect strongly vagal tone, were markedly higher in the runners than the controls. The findings suggest that an increased parasympathetic tone might at least partly explain the pronounced resting sinus bradycardias found in endurance-trained runners.

Bradycardia↗
PubMed1997

Lipoprotein A levels after intestinal bypass operation for morbid obesity.

BACKGROUND: Serum Lipoprotein A [Lp(a)] is considered an independent risk factor for cardiovascular disease. Reduction of other risk factors such as serum triglycerides and serum cholesterol is seen after weight reduction but it has been difficult to demonstrate a similar reduction of Lp(a). In this study Lp(a) is studied following weight reduction after intestinal bypass surgery for obesity. METHODS: A cross-sectional study was performed in which Lp(a) levels were compared between patients operated with intestinal bypass surgery for obesity (bilio-intestinal bypass) and a closely matched control group. The controls were chosen so as to correspond to the operated patients' preoperative body mass indices. RESULTS: The operated group had reduced their body mass index from a mean of 42 kg/m2 to a mean of 29 kg/m2 and had a significantly lower mean serum Lp(a) level (113 mg/l, SEM 34) than controls (207 mg/l, SEM 37), p < 0.05. CONCLUSION: Lowered Lp(a) levels are correlated to substantial weight loss following intestinal bypass surgery for obesity.

Adult↗
PubMed1997

Enteral nutrition therapy.

Nursing care is key to positive outcomes in patients who require enteral nutrition. Understanding the decision-making process for the use of this therapy along with the steps of feeding initiation, advancement, monitoring, and complication prevention, gives nursing personnel the tools they need to deliver nutrition in a safe, cost-effective manner. This article presents this essential information to help nurses care for patients who are receiving enteral nutrition.

Contraindications↗
PubMed1996

Voluntary ethanol intake in the rat: effects of nicotinic acetylcholine receptor blockade or subchronic nicotine treatment.

It has been suggested that the mesolimbic dopamine activating and the reinforcing properties of ethanol involve activation of central nicotinic acetylcholine receptors. To test this hypothesis, the effects of two nicotinic receptor antagonists and of subchronic nicotine treatment on voluntary ethanol consumption (ethanol 6% v/v or water) were studied in ethanol low-, medium- or high-preferring Wistar rats. After systemic mecamylamine (2 mg/kg) but not hexamethonium (0 mg/kg) high- but not low-preferring rats decreased their ethanol intake but, however, not their ethanol preference. When subchronically exposed to nicotine (0.35 mg/kg, s.c. daily) medium-preferring rats markedly increased their ethanol intake and preference. This effect lasted for more than 1 week after interrupting nicotine administration. Ethanol intake levels did not correlate with locomotor activity scores after nicotine challenge (0.35 mg/kg, s.c.) or with exploratory locomotor activity. However, exploratory locomotor activity correlated with locomotor activity scores both after nicotine (0.35 mg/kg, s.c.) and ethanol (0.125 g/kg i.p.) challenge. Dopamine release, as indicated by accumulation of 3-methoxytyramine after monoamine oxidase inhibition, was increased in the limbic forebrain (including the nucleus accumbens, the olfactory tubercles, the amygdala and the septum) after acute nicotine (0.35 mg/kg s.c.) or ethanol (2.5 g/kg i.p.) in animals subchronically exposed to nicotine compared to subchronically vehicle-treated controls. The present results further implicate central nicotinic receptors in the molecular events mediating the reinforcing properties of ethanol, and suggest that subchronic nicotine enhances the responsiveness of mesolimbic dopamine neurons both to nicotine and to ethanol. Clinical implications are discussed.

Alcohol Drinking↗
PubMed1996

Detection of empty HLA class II molecules on cord blood B cells.

Fetal mononuclear cells are increasingly used in transplantation of hematopoietic cells due to a reportedly lower incidence of graft-versus-host disease. Previous studies of immune responses of fetal lymphocytes have indicated a general hyporesponsiveness in response to polyclonal stimulation. Fetal B lymphocytes display many features typical of the resting state such as a low level of HLA class II expression, but a large proportion of cells also carry the activation-associated CD23 antigen. We show here that despite a low cell surface level of all three HLA class II isotypes on fetal B cells, their allogeneic capacity, measured as the ability to elicit a mixed lymphocyte reaction, is similar to that of adult B cells. Allogeneic stimulation is believed to be peptide-dependent. Surprisingly, the majority of the HLA class II molecules on cord blood B cells appeared to be devoid of stably bound peptide as detected by the binding of a recombinant and soluble invariant chain, as well as by the absence of sodium dodecyl sulfate (SDS) stable alpha beta heterodimers in whole cell lysates. Immunoblot experiments showed that HLA class II molecules of fetal B cells were predominantly present in high molecular weight aggregates in stark contrast to B cells of adult origin. However, a sensitive cell surface labeling technique followed by immunoprecipitation enabled us to detect an SDS-stable 120-kD molecule on fetal B cells. We propose that the 120-kD molecules could correspond to HLA class II doubledimers or superdimers. We hypothesize that the 120-kD HLA class II molecule functions as the antigen-presenting molecule in the mixed lymphocyte reaction of fetal B cells, as it is the major species detected on the surface. Secondly, we suggest that a high level of empty HLA class II molecules may be indicative of a particular stage in B-cell ontogeny.

Adult↗
PubMed1996

Luminescent oxygen channeling assay (LOCI): sensitive, broadly applicable homogeneous immunoassay method.

Luminescent oxygen channeling assay (LOCI) is a homogeneous immunoassay method capable of rapid, quantitative determination of a wide range of analytes--including high and very low concentrations of large and small molecules, free (unbound) drugs, DNA, and specific IgM. Assays have been carried out in serum and in lysed blood. Reliable detection of 1.25 microU/L thyrotropin (TSH) and 5 ng/L hepatitis B surface antigen (HBsAg) corresponds to detection limits approximately 3- and approximately 20-fold lower, respectively, than those of the best commercially available assays. An assay of chorionic gonadotropin is capable of quantification over a 10(6)-fold range of concentrations without a biphasic response. Latex particle pairs are formed in the assay through specific binding interactions by sequentially combining the sample and two reagents. One particle contains a photosensitizer, the other a chemiluminescer. Irradiation causes photosensitized formation of singlet oxygen, which migrates to a bound particle and activates the chemiluminescer, thereby initiating a delayed luminescence emission. Assay times range from 1 to 25 min.

Antigens, Viral↗
PubMed1994

Autonomic cardiovascular control in normal and pre-eclamptic pregnancy.

BACKGROUND: Pre-eclampsia is regarded as a primary placental disorder, in which defect placentation causes endothelial and cardiovascular disturbances. Evidence of disturbed neural cardiovascular control in this condition has been suggested, as well as in other hypertensive diseases. The purpose of the present study was to non-invasively evaluate the sympathovagal balance during normal and pre-eclamptic pregnancy. METHODS: In twelve healthy pregnant women, thirteen pre-eclamptic women and ten nonpregnant controls, heart rate, blood pressure and breathing movements were registered and recorded on a tape recorder for off-line analysis. Variability in heart rate, blood pressure and breathing movements were computed by an autoregressive spectral analysis algorithm. Heart rate variability was quantitated as the area under the spectral curve, and Student's t-test was performed on logarithmic values. RESULTS: Heart rate variability contained two major components in power, a low frequency peak predominantly attributed to sympathetic tone, and a high frequency peak reflecting vagal tone. Women with pre-eclampsia were characterized by a significantly reduced high frequency peak compared to healthy pregnant (p = 0.03) and non-pregnant (p = 0.02) women. In the low frequency band there were no significant differences in power between the groups. Blood pressure variability did not differ between the groups. CONCLUSIONS: The present results indicate that pre-eclampsia is associated with decreased vagal control of the heart. Furthermore, the results indicate that pregnancy per se does not change sympatho-vagal balance.

Adult↗
PubMed1992

Cell phenotype (CD23)-dependent variation in EBV genome copy numbers within lymphoblastoid cell lines (LCL).

Three Epstein-Barr-virus-transformed lymphoblastoid cell lines (LCL) were analysed on the basis of their CD23 expression. Levels of EBV-DNA were compared in the positive and negative subpopulations. Two lines were further analysed with regard to EBNA, cytoplasmic immunoglobulin (cIg) and lytic (EA/VCA) protein expression. Both subpopulations had a similar MHC class-II transcription, but the CD23- subpopulation had a lower plating efficiency and a lower rate of DNA synthesis. In the B6, NAD50 and 0467.3 cell lines, CD23- cells contained 2 +/- 0.2 - 6.4 +/- 3.0 times less EBV DNA than the corresponding CD23+ population. EBNA was expressed in 81 +/- 4.2% - 93 +/- 3.8% of the CD23+ cells and in 0 - 46 +/- 8.0% of the CD23- cells. No CD23+ cells in B6 or NAD50 contained any EA/VCA, while 19 +/- 2.8% - 24 +/- 4.2% of the CD23- cells were positive for the lytic-cycle-associated antigens. Of the CD23- cells, 70 +/- 8.6% - 86 +/- 6.0% were positive for cytoplasmic immunoglobulin compared to 14.7 +/- 2.7% - 14.9 +/- 1.8% in the corresponding CD23+ population. We have previously shown that only 18% of the cIg-positive cells were EBNA-positive in the B6 line compared to 94% in the cIg- population. This was open to 2 alternative interpretations: loss of EBV genomes from a fraction of the cells with subsequent differentiation to secretory immunoglobulin production, or down-regulation of EBNA expression in differentiating, EBV-genome-positive cells. Our present findings speak for the first alternative, indicating that a certain proportion of the cells may lose their EBV genomes in both long-established and freshly transformed LCLs. This is accompanied by a reduced percentage of EBNA-positive cells, the disappearance of at least one activation marker (CD23) associated with the virally induced blast transformation, and an increased synthesis of cIg.

Antibody Formation↗
PubMed1986

On the biomechanics of cycling. A study of joint and muscle load during exercise on the bicycle ergometer.

The aim of the study was to quantify the load induced in the lower limb joints and muscles during exercise on a bicycle ergometer and to study how these loads changed with adjustments of the bicycle ergometer or cycling technique. The forces, load moments and muscular power output acting on and about the hip, knee and ankle joints during cycling were determined using cine-film, pedal force measurements and biomechanical calculations based upon static and dynamic mechanics. The muscular activity of eleven lower limb muscles was recorded and quantified using EMG. The load moments acting about the bilateral hip, knee and ankle joint axes were found to be generally lower than those induced during normal level walking. The varus and valgus load moments acting about the antero-posterior knee joint axis were approximately the same as those induced during walking. The tibio-femoral compressive joint force and the anteriorly directed tibio-femoral shear force mainly stressing the anterior cruciate ligament were low. The talocrural joint compressive force and achilles tendon tensile force were low compared to those in level walking. The magnitude of lower limb muscular activity during cycling approximated that obtained during walking, with three major exceptions. M. vastus medialis et lateralis were more activated during cycling than during walking, and tibialis anterior was less activated. The hip extensor muscles produced 27%, hip flexors 4%, knee extensors 39%, knee flexors 10% and ankle plantar flexors 20% of the total positive mechanical work. Of the four parameters studied (workload, pedalling rate, saddle height, pedal foot position) workload was the most important adjustment factor for change of joint load and muscular activity. An increased pedalling rate increased the muscular activity in most of the muscles investigated, generally without changing the joint load. Increased saddle height decreased the maximum flexing knee load moment, but did not significantly change the flexing hip or dorsiflexing ankle load moment. Muscular activity in most of the muscles investigated was not generally changed by different saddle heights. Use of a posterior foot position instead of an anterior decreased the dorsiflexing ankle load moment, increased the gluteus medius and rectus femoris activity, and decreased soleus muscular activity but did not significantly change the hip or knee moments. It is suggested that cycling might be a useful exercise in the rehabilitation of patients with injuries to the anterior cruciate ligament, medial collateral ligament of the knee or achilles tendon.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1972

Location of glycoproteins that contain glucosamine in plant tissues.

When radioactive d-glucosamine is provided to Acer pseudoplatanus cells in liquid culture in order to label those glycoproteins that contain amino sugars, it is incorporated predominantly into a crude cell wall fraction. This observation was confirmed histologically by preparing autoradiographs of thin tissue sections from plasmolyzed cells. Highly purified cell wall material from unlabeled cells has also been shown to contain small amounts of glucosamine. Similarly, about one-half of the amino sugar recovered from cultured cells of Nicotiana tabacum is present in their cell walls. In corn roots, however, the labeled glycoproteins that are formed after glucosamine incorporation are predominantly cytoplasmic and not deposited outside the protoplast.

Journal Article↗
PubMedDate not supplied

Psychosocial factors and heart rate variability in healthy women.

OBJECTIVE: This study was conducted to investigate associations between psychosocial risk factors, including social isolation, anger and depressive symptoms, and heart rate variability in healthy women. METHODS: The study group consisted of 300 healthy women (median age 57.5 years) who were representative of women living in the greater Stockholm area. For the measurement of social isolation, a condensed version of the Interpersonal Support Evaluation List was used and household size assessed. Anger was measured by the anger scales previously used in the Framingham study and depressive symptoms by a questionnaire derived from Pearlin. Health behaviors were measured by means of standard questionnaires. From 24-hour ambulatory electrocardiographic monitoring, both time and frequency domain measures were obtained: SDNN index (mean of the SDs of all normal to normal intervals for all 5-minute segments of the entire recording), VLF power (very low frequency power), LF power (low frequency power), HF power (high frequency power), and the LF/HF ratio (low frequency by high frequency ratio) were computed. RESULTS: Social isolation and inability to relieve anger by talking to others were associated with decreased heart rate variability. Depressive symptoms were related only to the LF/HF ratio. Adjusting for age, menopausal status, exercise and smoking habits, history of hypertension, and BMI did not substantially change the results. CONCLUSIONS: These findings suggest heart rate variability to be a mediating mechanism that could explain at least part of the reported associations between social isolation, suppressed anger, and health outcomes.

Adult↗