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Biomedical subjects

J H Kristensen

Publications and source records attributed to J H Kristensen.

At least 19 recordsLinked to original sources
PubMed2006

Transfer of the antidepressant mirtazapine into breast milk.

AIMS: To investigate the transfer of mirtazapine and desmethylmirtazapine into milk and to calculate dose to the infant via milk. METHODS: Plasma and milk samples were obtained from eight breast-feeding women who were taking a median dose of 38 mg mirtazapine per day. Milk/plasma ratio (M/P) and infant doses were estimated by standard methods. The infants were examined clinically and in four infants blood was taken for analysis. RESULTS: Mean (95% confidence interval) relative infant doses for mirtazapine and desmethylmirtazapine (n = 8) were 1.5% (0.8, 2.2) and 0.4% (0.2, 0.6) respectively. The mean M/P (area under curve n = 4, single or paired samples n = 3) was 1.1 (0.7,1.5) for mirtazapine and 0.6 (0.5, 0.7) for desmethylmirtazapine. No adverse effects were seen. Mirtazapine was detected (1.5 microg l(-1)) in only one of four infants tested. CONCLUSION: We suggest that mirtazapine use by lactating women is safe for the breast-fed infant. Nevertheless, each decision to breast feed should always be made on the basis of an individual risk/benefit analysis.

Antidepressive Agents, Second-Generation↗
PubMed2002

Transfer of metformin into human milk.

AIMS/HYPOTHESIS: The aim of this study was to characterize the milk-to-plasma ratio and infant dose for metformin in breastfeeding women, and to measure plasma concentrations and assess any effects in their infants. We hypothesized that metformin used by mothers is safe for their breastfed infants. METHODS: Seven women taking metformin (median dose 1500 mg orally daily) and their infants were studied. Metformin concentrations in plasma and milk were measured by high performance liquid chromatography. Infant exposure was estimated as the product of estimated milk production rate and the average concentration of the drug in milk and also expressed as a percentage of the weight-normalized maternal dose. RESULTS: The mean milk-to-plasma ratio for metformin was 0.35 (95%CI 0.2-0.5). The mean of its average concentrations in milk over the dose interval was 0.27 mg/l (0.15-0.39 mg/l). The absolute infant dose averaged 0.04 mg x kg(-1) x day(-1) (0.02-0.06 mg x kg(-1) x day(-1)) and the mean relative infant dose was 0.28% (0.16-0.4%). Metformin was present in very low or undetectable concentrations in the plasma of four of the infants who were studied. No health problems were found in the six infants who were evaluated. CONCLUSIONS/INTERPRETATION: The concentrations of metformin in breast milk were generally low and the mean infant exposure to the drug was only 0.28% of the weight-normalized maternal dose. As this is well below the 10% level of concern for breastfeeding, and because the infants were healthy, we conclude that metformin use by breastfeeding mothers is safe. Nevertheless, each decision to breastfeed should be made after conducting a risk:benefit analysis for each mother and her infant.

Adult↗
PubMed2001

Serum hepatocyte growth factor levels in patients with chronic renal disease--effect of GFR and pathogenesis.

UNLABELLED: Hepatocyte growth factor (HGF) is a growth-promoting peptide that appears to act in a renotropic and nephroprotective manner during acute renal damage. Recent studies suggest that HGF is also of importance in chronic renal diseases. The serum HGF level is correlated with serum creatinine, and it has been suggested that glomerular and tubular diseases affect serum HGF differently. In the present study. levels of serum HGF were determined and correlated to glomerular filtration rate (GFR) in 118 patients with various chronic renal diseases. GFR was determined by 99mTc-DTPA clearance, and the GFR values were evenly distributed in the interval 5-155 mL/min/1.73 m2. Serum HGF levels increased slightly with decreasing GFR: the Pearson correlation coefficient being 0.49 (p<0.0001). In 21 additional patients with end-stage renal disease treated with continuous ambulatory peritoneal dialysis, there was a more marked increase in the serum levels of HGF. The effect of glomerular and tubular diseases on serum HGF was examined by comparing the HGF levels in two groups of patients with similar GFR values: 57 patients with mainly glomerular disorders (diabetic nephropathy with micro- or macroalbuminuria or glomerulonephritis) and 14 patients with mainly tubular disorders (polycystic kidney disease). There was no significant difference between the HGF levels of the two groups (p=0.30). IN CONCLUSION: Serum HGF levels are correlated with GFR (for GFR > or = 5 mL/min/1.73 m2) in patients with chronic renal diseases, and glomerular and tubular disorders seem to affect the HGF level similarly.

Adult↗
PubMed2001

Effect of glutamine supplementation on exercise-induced changes in lymphocyte function.

The purpose of this study was to investigate the possible role of glutamine in exercise-induced impairment of lymphocyte function. Ten male athletes participated in a randomized, placebo-controlled, double-blind crossover study. Each athlete performed bicycle exercise for 2 h at 75% of maximum O(2) consumption on 2 separate days. Glutamine or placebo supplements were given orally during and up to 2 h postexercise. The trial induced postexercise neutrocytosis that lasted at least 2 h. The total lymphocyte count increased by the end of exercise due to increase of both CD3(+)TCR alpha beta(+) and CD3(+)TCR gamma delta(+) T cells as well as CD3(-)CD16(+)CD56(+) natural killer (NK) cells. Concentrations of CD8(+) and CD4(+) T cells lacking CD28 and CD95 on their surface increased more than those of cells expressing these receptors. Within the CD4(+) cells, only CD45RA(-) memory cells, but not CD45RA(+) naive cells, increased in response to exercise. Most lymphocyte subpopulations decreased 2 h after exercise. Glutamine supplementation abolished the postexercise decline in plasma glutamine concentration but had no effect on lymphocyte trafficking, NK and lymphokine-activated killer cell activities, T cell proliferation, catecholamines, growth hormone, insulin, or glucose. Neutrocytosis was less pronounced in the glutamine-supplemented group, but it is unlikely that this finding is of any clinical significance. This study does not support the idea that glutamine plays a mechanistic role in exercise-induced immune changes.

Adult↗
PubMed2000

Citalopram and demethylcitalopram in human milk; distribution, excretion and effects in breast fed infants.

AIMS: To characterize milk/plasma (M/P) ratio and infant dose, for citalopram and demethylcitalopram, in breast-feeding women taking citalopram for the treatment of depression, and to determine the plasma concentration and effects of these drugs in their infants. METHODS: Seven women (mean age 30.6 years) taking citalopram (median dose 0.36 mg kg(-1) day(-1)) and their infants (mean age 4.1 months) were studied. Citalopram and demethylcitalopram in plasma and milk were measured by high-performance liquid chromatography over a 24 h dose interval. Infant exposure was estimated (two separate methods) as the product of milk production rate and drug concentration in milk, normalized to body weight and expressed as a percentage of the weight-adjusted maternal dose. RESULTS: Mean M/PAUC values of 1.8 (range 1.2-3) and 1.8 (range 1.0-2.5) were calculated for citalopram and demethylcitalopram, respectively. The mean maximum concentrations of citalopram and demethylcitalopram in milk were 154 (95% CI, 102-207) microg l(-1) and 50 (23-77) microg l(-1). Depending on the method of calculation, mean infant exposure was 3.2 or 3.7% for citalopram and 1.2 or 1.4% for demethylcitalopram. Citalopram (2.0, 2.3 and 2.3 microg l(-1)) was detected in three of the seven infants. Demethylcitalopram (2.2 and 2.2 microg l(-1) was detected in plasma from two of the same infants. No adverse effects were seen in the infants, all were within appropriate percentile limits for weight and all had normal Denver developmental quotients. CONCLUSIONS: The mean combined dose of citalopram and demethylcitalopram (4.4-5.1% as citalopram equivalents) transmitted to infants via breast milk is below the 10% notional level of concern. Plasma concentrations of these drugs in the infants were very low or absent and there were no adverse effects. These data support the safety of the use of citalopram in breast feeding women. Nevertheless, each decision to breast feed should always be made as an individual risk:benefit analysis.

Adult↗
PubMed2000

Drowsiness and poor feeding in a breast-fed infant: association with nefazodone and its metabolites.

OBJECTIVE: To investigate whether adverse effects in a premature neonate could be attributed to nefazodone exposure via breast milk. CASE SUMMARY: The breast-fed white infant (female, 2.1 kg, 36 weeks corrected gestational age) of a 35-year-old woman (60 kg) taking nefazodone 300 mg/d was admitted to the hospital because she was drowsy, lethargic, unable to maintain normal body temperature, and was feeding poorly. A diagnosis of exposure to nefazodone via breast milk was considered only after other more likely diagnoses had been excluded. After breast feeding was discontinued, the infant's symptoms resolved slowly over a period of 72 hours. The maternal plasma and milk concentration-time profiles for nefazodone and its metabolites, triazoledione, HO-nefazodone, and m-chlorphenylpiperazine, were quantified by HPLC. The calculated infant dose for nefazodone and its active metabolites (as nefazodone equivalents) via the milk was only 0.45% of the weight-adjusted maternal nefazodone daily dose. DISCUSSION: Our data suggest a putative association between maternal nefazodone ingestion and adverse effects in a premature breast-fed neonate. The measured amount of drug exposure would normally be considered safe in a full-term infant. However, there was a temporal relationship between resolution of adverse effects in the infant and cessation of breastfeeding. CONCLUSIONS: This case highlights the importance of individualizing the risk-benefit analysis for exposure to antidepressants in breast milk, especially when dealing with premature neonates.

Adult↗
PubMed1999

Separation of (2)H MAS NMR spectra by two-dimensional spectroscopy.

New methods for optimum separation of (2)H MAS NMR spectra are presented. The approach is based on hypercomplex spectroscopy that is useful for sign discrimination and phase separation. A new theoretical formalism is developed for the description of hypercomplex experiments. This exploits the properties of Lie algebras and hypercomplex numbers to obtain a solution to the Liouville-von Neumann equation. The solution is expressed in terms of coherence transfer functions that describe the allowed coherence transfer pathways in the system. The theoretical formalism is essential in order to understand all the features of hypercomplex experiments. The method is applied to the development of two-dimensional quadrupole-resolved (2)H MAS NMR spectroscopy. The important features of this technique are discussed and two different versions are presented with widely different characteristics. An improved version of two-dimensional double-quantum (2)H MAS NMR spectroscopy is developed. The conditions under which the double-quantum experiment is useful are discussed and its performance is compared with that observed for the quadrupole-resolved experiments. A general method is presented for evaluating the optimum pulse sequence parameters consistent with maximum sensitivity and resolution. This approach improves the performance of the experiments and is essential for any further development of the techniques. The effects of finite pulse width and hypercomplex data processing may lead to both intensity and phase distortions in the spectra. These effects are analyzed and general correction procedures are suggested. The techniques are applied to polycrystalline malonic-acid-(2)H(4) for which the spinning sideband manifolds from the carboxyl and methylene deuterons are separated. The spinning sideband manifolds are simulated to determine the quadrupole parameters. The values are consistent with previous results, indicating that the techniques are both accurate and reliable.

Crystallization↗
PubMed1999

Distribution and excretion of fluoxetine and norfluoxetine in human milk.

AIMS: To characterize milk/plasma (M/P) ratio and infant dose, for fluoxetine and norfluoxetine, in breast-feeding women taking fluoxetine for the treatment of depression, and to determine the plasma concentration of these drugs in their infants. METHODS: Fourteen women (mean age 32.2 years) taking fluoxetine (mean dose 0.51 mg kg-1 day-1 ) and their infants (mean age 3.4 months) were studied. Fluoxetine and norfluoxetine in plasma and milk were measured by high-performance liquid chromatography over a 24 h dose interval in four patients, and by single point data collection in 10 patients. Infant exposure was estimated as the product of estimated milk production, and average drug concentration in milk, normalized to body weight and expressed as a percentage of the weight-adjusted maternal dose. RESULTS: Mean M/P values of 0.68 (95% CI 0.52-0.84) and 0.56 (95% CI 0.35-0.77) were calculated for fluoxetine and norfluoxetine, respectively. Mean total infant exposure (fluoxetine equivalents) was estimated to be 6.81% (range 2.15-12%) of the weight-adjusted maternal dose of fluoxetine. Contributions from fluoxetine and norfluoxetine were approximately equal. Fluoxetine (range 20-252 microgram l-1 ) was detected in five of the nine infants from whom samples were collected, and norfluoxetine (range 17-187 microgram l-1 ) was detected in seven of the nine infants. The highest of these concentrations was about 70% of the maternal plasma concentrations. CONCLUSIONS: The mean combined dose of fluoxetine and norfluoxetine transmitted to infants via breast milk is below the 10% notional level of concern. However, there was considerable interpatient variability in estimated infant dose and in some of the patients, the dose was >10%. Further, since adverse effects have been observed in breast-fed infants, careful monitoring of the infants is mandatory. Neonates exposed to these drugs in utero had higher concentrations of fluoxetine and norfluoxetine and are at greater risk of adverse effects.

Adult↗
PubMed1999

A narrative review on classification of pain conditions of the upper extremities.

Local and regional musculoskeletal discomfort and pain in the shoulder girdle or upper extremities are often reported, especially in the working population. In this review we describe the most important problems and factors when classifying musculotendinous pain in the upper extremities and shoulders. This includes an analysis of how four common diagnoses (wrist tenosynovitis, lateral epicondylitis, rotator-cuff tendinitis, myofascial pain syndrome) fulfil basic criteria of validity. It is evident that there are some serious problems regarding the validity of the current classification of the conditions. Clinical criteria are often poorly defined and the reliability insufficiently tested. The relationship to objective pathoanatomic or physiological findings seems inconsistent. Although magnetic resonance and ultrasonographic imaging are promising, they are still only preliminary methods for evaluation of tendon and connective tissue structures. The prognosis with and without treatment also seems heterogeneous and can vary between studies. A generally accepted terminology is lacking in the pathogenetically complex regional muscle pain conditions.

Acute Disease↗
PubMed1999

Evaluation of the Dade Behring N Latex Cystatin C assay on the Dade Behring Nephelometer II System.

The Dade Behring N Latex Cystatin C assay, a particle-enhanced nephelometric immunoassay for measuring serum cystatin C, was evaluated on the Dade Behring Nephelometer II. The assay time was 6 min and the throughput was 75 samples per hour. The sample volume was 40 microL and the measuring range was 0.25-7.90 mg/L. Imprecision studies revealed within-run CVs < 1.8% and between-run CVs < 1.8% in the concentration range 0.87-4.63 mg/L. Recovery was 92.4-101.3%. Linearity studies showed excellent correlation between the theoretical and obtained values. No interferences were detected from haemoglobin < 1.0 mmol/ L, bilirubin <512 micromol/L and Intralipid <20 g/L. Stability of cystatin C in serum was 7 days at temperatures from 20 degrees C to 20 degrees C and 6 months at -80 degrees C. Measurements of cystatin C in heparin-plasma and EDTA-plasma did not differ significantly from cystatin C measured in serum. Fifty patient samples run on the Dade Behring Nephelometer II (y) were compared to the Dako Cystatin C assay (x). The Passing-Bablok regression analysis revealed y = 1.105x - 0.340. In conclusion, the Dade Behring N Latex Cystatin C assay was precise and correlated with the Dako Cystatin C assay.

Calibration↗
PubMed1999

Randomised controlled trial of cisapride in preterm infants.

AIM: To determine the effect of cisapride on gastrointestinal motility in preterm infants. METHODS: Cisapride (0.2 mg/kg, 8 hourly ) or placebo was given first for seven days in a double blind randomised crossover study of 10 preterm infants. Gastrointestinal motility was assessed on day 3 of each treatment. The half gastric emptying time (GET1/2) was determined by using ultrasonography to measure the decrease in the gastric antral cross sectional area after a feed. The whole gastrointestinal transit time (WGTT) was assessed by timing the transit of carmine red through the gut. Treatments were compared using the Wilcoxon matched pairs signed ranks test. RESULTS: Median (range) birthweight was 1200 (620, 1450) g and postconceptional age 33 (29, 34) weeks at recruitment. GET1/2 was significantly longer during cisapride treatment than during placebo; the median of the differences (95% confidence interval) was 19.2 (11, 30 minutes, p=0.008). WGTT was also longer during cisapride treatment, but the difference was not significant; the median of the differences was 11(-18, 52 hours, p=0.1). CONCLUSIONS: Cisapride delays gastric emptying and may delay WGTT in preterm infants. Its use to promote gastrointestinal motility in this group cannot be recommended.

Cisapride↗
PubMed1998

Incidence and clinical epidemiology of necrobacillosis, including Lemierre's syndrome, in Denmark 1990-1995.

To establish the incidence and describe the clinical epidemiology of necrobacillosis and Lemierre's syndrome in Denmark, the clinical records of all laboratory-recorded cases of septicaemia due to Fusobacterium necrophorum biovar A, B, and C were reviewed retrospectively during a 6-year period. The incidence of necrobacillosis and Lemierre's syndrome was 1.5 and 0.8 per million persons per year, respectively, showing a tendency to increase during the period. Fusobacterium necrophorum was grown after three days' incubation, but the characteristic pleomorphic fusiform morphology was often disregarded as an important help in diagnosing necrobacillosis. The 24 patients with Lemierre's syndrome were all young and previously healthy, and none died, but pre-hospital delay was associated with a significantly higher morbidity and risk of metastatic infections. The remaining 25 patients with necrobacillosis had a high mortality, 24%, which was correlated with age and predisposing diseases, especially cancers. These findings stress the importance of a quicker clinical and microbiological diagnosis in cases of Lemierre's syndrome, and of screening for cancer in the remaining cases of necrobacillosis.

Adolescent↗
PubMed1998

Investigation of multiaxial molecular dynamics by 2H MAS NMR spectroscopy.

The technique of 2H MAS NMR spectroscopy is presented for the investigation of multiaxial molecular dynamics. To evaluate the effects of discrete random reorientation a Lie algebraic formalism based on the stochastic Liouville-von Neumann equation is developed. The solution to the stochastic Liouville-von Neumann equation is obtained both in the presence and absence of rf irradiation. This allows effects of molecular dynamics to be evaluated during rf pulses and extends the applicability of the formalism to arbitrary multiple pulse experiments. Theoretical methods are presented for the description of multiaxial dynamics with particular emphasis on the application of vector parameters to represent molecular rotations. Numerical time and powder integration algorithms are presented that are both efficient and easy to implement computationally. The applicability of 2H MAS NMR spectroscopy for investigating molecular dynamics is evaluated from theoretical spectra. To demonstrate the potential of the technique the dynamics of thiourea-2H4 is investigated experimentally. From a series of variable temperature MAS and quadrupole echo spectra it has been found that the dynamics can be described by composite rotation about the CS and CN bonds. Both experiments are sensitive to the fast CS rotation which is shown to be described by the Arrhenius parameters E(CS) = 46.4 +/- 2.3 kJ mol(-1) and ln(A(CS))= 32.6 +/- 0.9. The MAS experiment represents a significant improvement by simultaneously allowing the dynamics of the slow CN rotation to be fully characterized in terms of E(CN) = 56.3 +/- 3.4 kJ mol(-1) and ln(A(CN)) = 25.3 +/- 1.1.

Magnetic Resonance Spectroscopy↗
PubMed1998

Distribution and excretion of sertraline and N-desmethylsertraline in human milk.

AIMS: To characterise milk/plasma (M/P) ratio and infant exposure, for sertraline and N-desmethylsertraline, in breast-feeding women taking sertraline for the treatment of depression. METHODS: Eight women (mean age 28 years) taking sertraline (1.05 mg kg(-1) day(-1)) and their infants (mean age 5.7 months) were studied. Sertraline and N-desmethylsertraline in plasma and milk were measured by high-performance liquid chromatography over a 24 h dose interval at steady-state. M/P values were estimated from area under the plasma and milk concentration-time curves. All milk produced was collected over the dose interval. Infant exposure was estimated as the product of actual or estimated milk production, and average drug concentration in milk, normalized to body weight and expressed as a percentage of the weight-adjusted maternal dose. RESULTS: Mean milk production was 321 ml day(-1) (range 34-974 ml). Mean M/P values of 1.93 and 1.64 were calculated for sertraline and N-desmethylsertraline respectively. Infant exposure estimated from actual milk produced was 0.2% and 0.3% of the weight-adjusted maternal dose for sertraline and N-desmethylsertraline (as sertraline equivalents) respectively. When calculated from estimated milk production (0.15 l kg(-1) day(-1)), infant exposure was significantly greater (P<0.0001) at 0.90% and 1.32% for sertraline and N-desmethylsertraline respectively. Neither sertraline nor its N-desmethyl metabolite could be detected in plasma samples from the four infants tested. No adverse effects were observed in any of the eight infants and all had achieved normal developmental milestones. CONCLUSIONS: Irrespective of the method of calculation of infant exposure, the mean total dose of sertraline and its N-desmethyl metabolite transmitted to infants via breast-feeding is low and unlikely to cause any significant adverse effects.

1-Naphthylamine↗
PubMed1998

Distribution and excretion of venlafaxine and O-desmethylvenlafaxine in human milk.

AIMS: To characterise the transfer of venlafaxine (V) and its O-desmethyl metabolite (ODV) into human milk by measuring milk/plasma (M/P) ratio, and to estimate the likely dose received by a breast-fed infant. METHODS: Milk and plasma samples were collected from three lactating women who were taking venlafaxine for depression, and were at steady-state. In two of the patients, venous blood and milk samples were collected 0, 1, 2, 3, 4, 6, 8 and 12 h post dose, while in the third patient a single pair of blood and milk samples was obtained 0.83 h post dose. A plasma sample was obtained from each of their infants. V and ODV were measured in plasma and milk by high performance liquid chromatography. M/P was calculated and infant dose estimated as drug concentration in milk x a milk intake of 0.15 l kg(-1) day(-1), relative to the weight-adjusted maternal dose. RESULTS: Mean M/P for V was 4.1 (range 2.8-4.8) and 3.1 for ODV (range 2.8-3.8). The mean total infant dose (as V equivalents) was 7.6% (range 4.7-9.2%) of the maternal weight-adjusted dose, with approximately equal amounts of V (3.5%) and ODV (4.1%) in the dose. ODV (median 100 microg I(-1)) was detected in the plasma of all three infants. The infants were healthy and showed no acute adverse effects. CONCLUSIONS: These preliminary data show that the total dose of V and ODV ingested by breast-fed infants can be as high as 9.2% of maternal intake. Moreover there were measurable concentrations of ODV in the infants' plasma. We recommend that exposed infants should be observed closely.

Adult↗
PubMed1998

Serum cystatin C as a marker of the renal function.

The protease inhibitor cystatin C is a non-glycosylated low molecular weight protein (Mr=13359) which is produced by all nucleated cells at a constant rate, freely filtered by the renal glomeruli, and catabolized in the tubuli. The aim of the study was to elucidate the applicability of serum cystatin C as a marker of glomerular filtration rate (GFR) in patients with various kidney diseases with a wide range of renal function and in dialysis patients. Seventy-six patients with various kidney diseases (aged 20 to 79 years) and 61 dialysis patients (aged 21 to 82 years) were included. Serum cystatin C was measured by automated particle-enhanced immunoturbidimetry, serum and urine creatinine by an enzymatic method, and GFR by 99mTc-DTPA-clearance using a single plasma sample method. Serum cystatin C in patients with various kidney diseases was 1.90+/-0.98 mg/L (mean+/-SD) and in dialysis patients 7.14+/-1.91 mg/L. In the non-dialysis patients a linear relationship was found between 99mTc-DTPA-clearance and 1/serum cystatin C (r=0.91, p-value<0.0001), 1/serum creatinine (r=0.89, p-value<0.0001), and creatinine-clearance (r=0.88, p-value<0.0001). Comparison of the non-parametric ROC plots for serum cystatin C (area under the curve (AUC)=0.9665; SE=0.0169), serum creatinine (AUC=0.9554; SE=0.0205), and creatinine-clearance (AUC=0.9731; SE=0.0160) revealed no significant differences (p-values: 0.50, 0.78, and 0.49). In conclusion, cystatin C may be a likewise good marker of the GFR as serum creatinine and creatinine-clearance, cystatin C having the advantage being independent of gender and muscle mass.

Adult↗
PubMed1998

Postoperative nausea and vomiting: development of a management protocol.

Postoperative nausea and vomiting (PONV) is still an important and common problem. Despite the introduction of new antiemetic drugs, the management of PONV remains difficult. In this article we describe the development and evaluation of a management protocol for PONV, which consists of a treatment algorithm accompanied by a nursing education program. Implementation of this management protocol has been well-accepted by staff, appears to have reduced delay in patient treatment and improved patient care, and has significantly reduced staff workload. It is planned to use continuous quality improvement techniques to further refine the algorithm and continue assessment of its efficacy and of patient satisfaction.

Antiemetics↗