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Biomedical subjects

M Hjelm

Publications and source records attributed to M Hjelm.

At least 19 recordsLinked to original sources
PubMed2002

Comparison of adhesion of the food spoilage bacterium Shewanella putrefaciens to stainless steel and silver surfaces.

AIMS: To compare the number of attached Shewanella putrefaciens on stainless steel with different silver surfaces, thus evaluating whether silver surfaces could contribute to a higher hygienic status in the food industry. METHODS AND RESULTS: Bacterial adhesion to three types of silver surface (new silver, tarnished silver and sulphide-treated silver) was compared with adhesion to stainless steel (AISI 316) using the Malthus indirect conductance method to estimate the number of cfu cm(-2). The number of attached bacteria on new silver surfaces was lower than on steel for samples taken after 24 h. However, this was not statistically significant (P > 0.05). The numbers of attached bacteria were consistently lower when tarnished silver surfaces were compared with stainless steel and some, but not all, experiments showed statistical significance (P < 0.05). Treating new silver with sulphide to reproduce a tarnished silver surface did not result in a similar lowering of adhering cells when compared with steel (P > 0.05). CONCLUSIONS: New or tarnished silver surfaces caused a slight reduction in numbers of attached bacteria; however, the difference was only sometimes statistically significant. SIGNIFICANCE AND IMPACT OF THE STUDY: The lack of reproducibility in differences in numbers adhering to the different surfaces and lack of statistical significance between numbers of adhered viable bacteria do not indicate that the tested silver surfaces can be used to improve hygienic characteristics of surfaces in the food industry.

Bacterial Adhesion↗
PubMed2001

Telepsychiatry in psychogeriatric service: a pilot study.

A pilot study on telepsychiatry was conducted in which a videoconferencing link was established between a regional hospital and a care and attention home. Using this system, a psychogeriatric outreach team provided 149 psychiatric assessments to 45 residents of the care and attention home over 11 months. Videoconferencing was found to be highly feasible. It was acceptable to staff and patients and more cost-effective than on-site visits.

Aged↗
PubMed2001

Growth and nutrition of Chinese vegetarian children in Hong Kong.

OBJECTIVE: The study investigated the nutritional status of Chinese lacto-ovo-vegetarian children aged 4-14 years. METHODOLOGY: Dietary intake over 7 days was assessed using a computer program, previously used for a local population-based dietary survey. Anthropometric measurements were made and fasting venous blood was examined for serum lipids, haematological data, iron, vitamin B12 and folate status. Bone mineral density (BMD) of the spine (L2 - L4) was measured as a reflection of calcium status. RESULTS: Fifty-one lacto-ovo-vegetarians aged 4-14 years were investigated. The mean +/- standard deviation (SD) daily energy intake was 1600 +/- 425 kcal. The mean (+/- SD) daily protein intake was 1.6 +/- 0.6 g/kg bodyweight which met the United States recommended dietary allowance. Compared to that of the local omnivore diet, the vegetarian diet was closer to the recommended healthy diet with lower fat (20-23%), more fibre (5.8-8.7 g/day) and better polyunsaturated to saturated fatty acid ratio (1.0-1.1). Growth and BMD of the vegetarian children were comparable to the general omnivore population. Two children had iron deficiency and two children had anaemia. The calcium status, as reflected by the BMD, was not impaired. Serum folate and vitamin B12 were within the normal range. Six (25%) boys and four (15%) girls were obese. Three boys had hyperlipidaemia. CONCLUSIONS: A Hong Kong Chinese vegetarian diet appears healthy, providing adequate iron and vitamin B12 nutrition, but the prevalence of obesity was high.

Adolescent↗
PubMed2001

Manganese intake and cholestatic jaundice in neonates receiving parenteral nutrition: a randomized controlled study.

UNLABELLED: Infants requiring parenteral nutrition (n = 244) were randomized to receive either 1 (group 1, n = 121) or 0.0182 micromol/kg/d (group 2, n = 123) of manganese supplementation. The whole-blood manganese and serum direct bilirubin concentrations of the infants were monitored, as was the development of cholestasis (peak serum direct bilirubin concentration >50 micromol/L). Subgroup analysis was carried out on the data of 78 infants in group 1 and 82 in group 2 who had received manganese supplementation and more than three-quarters of their total daily fluid as parenteral nutrition for >14 d. Of all the infants randomized, the high manganese group (group 1) showed a trend towards developing higher peak whole-blood manganese concentration [group 1 versus group 2: median (interquartile range): 606.0 (421.0; 1005.0) vs 566.0 (336.0: 858.0); p=0.061] and higher peak serum direct bilirubin concentration [37.0 (10.5; 122.5) vs 19.0 (8.0; 112.5); p=0.153], but the differences between the 2 groups did not reach statistical significance. The 2 groups did not differ in terms of the occurrence of cholestasis during parenteral nutrition (63/121 vs 57/123; p=0.444). Subgroup analysis of infants who had received more than three-quarters of their total daily fluid as parenteral nutrition showed, however, that the high manganese group developed significantly higher whole-blood manganese concentration [743.5 (498.0; 1211.0) vs 587.0 (438.0; 982.0); p=0.037] and serum direct bilirubin concentration [84.0 (28.0; 170.0) vs 25.5 (9.0; 117.0): p < 0.001]. Although there was no significant difference in the occurrence of cholestasis (58/78 vs 49/82; p = 0.073), more infants in the high manganese group developed a more severe degree of direct hyperbilirubinaemia, with peak serum direct bilirubin >100 micromol/L (32/78 vs 20/82; p = 0.038). CONCLUSION: We conclude that the pathogenesis of parenteral nutrition-related cholestasis is probably multifactorial, and that high manganese intake is a significant contributory factor.

Cholestasis↗
PubMed2001

Shewanella putrefaciens adhesion and biofilm formation on food processing surfaces.

Laboratory model systems were developed for studying Shewanella putrefaciens adhesion and biofilm formation under batch and flow conditions. S. putrefaciens plays a major role in food spoilage and may cause microbially induced corrosion on steel surfaces. S. putrefaciens bacteria suspended in buffer adhered readily to stainless steel surfaces. Maximum numbers of adherent bacteria per square centimeter were reached in 8 h at 25 degrees C and reflected the cell density in suspension. Numbers of adhering bacteria from a suspension containing 10(8) CFU/ml were much lower in a laminar flow system (modified Robbins device) (reaching 10(2) CFU/cm(2)) than in a batch system (reaching 10(7) CFU/cm(2)), and maximum numbers were reached after 24 h. When nutrients were supplied, S. putrefaciens grew in biofilms with layers of bacteria. The rate of biofilm formation and the thickness of the film were not dependent on the availability of carbohydrate (lactate or glucose) or on iron starvation. The number of S. putrefaciens bacteria on the surface was partly influenced by the presence of other bacteria (Pseudomonas fluorescens) which reduced the numbers of S. putrefaciens bacteria in the biofilm. Numbers of bacteria on the surface must be quantified to evaluate the influence of environmental factors on adhesion and biofilm formation. We used a combination of fluorescence microscopy (4',6'-diamidino-2-phenylindole staining and in situ hybridization, for mixed-culture studies), ultrasonic removal of bacteria from surfaces, and indirect conductometry and found this combination sufficient to quantify bacteria on surfaces.

Bacterial Adhesion↗
PubMed2000

Effect of labour and delivery on plasma hepatic enzymes in the newborn.

OBJECTIVE: To study the relationship between cord blood hepatic enzymes and obstetric and neonatal outcome in a Chinese population. MATERIALS AND METHODS: The study group consisted of 288 low-risk Chinese women with singleton term pregnancies. The following enzymes were assayed in cord blood: lactate dehydrogenase (LDH), glutamyl transferase (GGT), aspartate aminotransferase (AST) and alanine transferase (ALT). These were correlated to maternal and neonatal characteristics. RESULTS: A strong correlation was noted between cord blood AST and LDH (R = 0.582, p < 0.01), which was absent amongst those infants delivered by elective cesarean section. LDH, AST and ALT were negatively correlated with cord arterial pH and base excess (BE). GGT was inversely related only to gestational age (R = -0.18, p < 0.01). Both LDH and AST were weakly correlated with the duration of the first and second stages of labour. LDH was most closely linked to arterial pH, whereas AST was related to both arterial BE and duration of the second stage. CONCLUSIONS: The reference values are comparable to those published for Caucasian populations. There are moderate elevations in LDH and AST associated with the onset of labour and changes in acid-base status.

Acid-Base Equilibrium↗
PubMed1999

Maternal serum screening for Down syndrome in a teaching hospital in Hong Kong.

OBJECTIVE: To study prospectively the use of maternal serum alpha-fetoprotein (AFP) and total beta-human chorionic gonadotropin (hCG) concentrations for screening of Down syndrome in Hong Kong. METHODS: AFP and total beta-hCG were measured in serum samples from 1638 singleton Chinese pregnancies at 14-22 weeks of gestation, recruited over a twelve-month period. Gestational ages were determined by ultrasonographic parameters measured at the same visit as the test for all cases. The gestational-age-specific and weight-adjusted medians for serum AFP and total beta-hCG were calculated. Risk for fetal Down syndrome (FDS) was derived by mathematical modeling of the medians together with maternal age. Amniocenteses were offered to women with a calculated FDS risk of 1:270 or greater. RESULTS: The gestational-age-specific and weight-adjusted medians for maternal serum AFP were similar to previous studies while that of total beta-hCG were higher. A total of 101 patients (6.1%) were classified as being high risk for FDS, including 3.4% (48/1394) of those younger than 35 years of age and 21.7% (53/244) of those who were 35 or above. There were 4 cases of Down syndrome, 1 case of Tumer syndrome and 1 of Edward syndrome. Three out of the four cases of Down syndrome were screened positive, corresponding to a detection rate of FDS of 75%. A case of Tumer syndrome was also screened positive. A case of trisomy 18 was found to have very low levels of AFP [0.262 multiple of median (MoM)] and total beta-hCG (0.115 MoM). CONCLUSIONS: Maternal serum screening using double biochemical markers (AFP and total beta-hCG) in combination with gestational dating by ultrasonography is effective in the detection of fetal Down syndrome and possibly other chromosomal disorders in Chinese pregnant women.

Adult↗
PubMed1998

Contrasting plasma free amino acid patterns in elite athletes: association with fatigue and infection.

AIM: There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis of this pattern in the medical screening of elite athletes during both especially intense and light training periods. METHODS: Plasma amino acid analysis was undertaken in three situations. (1) A medical screening service was offered to elite athletes during an intense training period before the 1992 Olympics. Screening included a blood haematological/biochemical profile and a microbial screen in athletes who presented with infection. The athletes were divided into three groups who differed in training fatigue and were considered separately. Group A (21 track and field athletes) had no lasting fatigue; group B (12 judo competitors) reported heavy fatigue at night but recovered overnight to continue training; group C (18 track and field athletes, one rower) had chronic fatigue and had been unable to train normally for at least several weeks. (2) Athletes from each group were further screened during a post-Olympic light training period. (3) Athletes who still had low amino acid levels during the light training period were reanalysed after three weeks of additional protein intake. RESULTS: (1) The pre-Olympics amino acid patterns were as follows. Group A had a normal amino acid pattern (glutamine 554 (25.2) micromol/l, histidine 79 (6.1) micromol/l, total amino acids 2839 (92.1) micromol/l); all results are means (SEM). By comparison, both groups B and C had decreased plasma glutamine (average 33%; p<0.001) with, especially in group B, decreased histidine, glucogenic, ketogenic, and branched chain amino acids (p<0.05 to p<0.001). None in group A, one in group B, but ten athletes in group C presented with infection: all 11 athletes had plasma glutamine levels of less than 450 micromol/l. No intergroup differences in haematological or other blood biochemical parameters, apart from a lower plasma creatine kinase activity in group C than in group B (p<0.05) and a low neutrophil to lymphocyte ratio in the athletes with viral infections (1.2 (0.17)), were found. (2) During post-Olympic light training, group A showed no significant amino acid changes. In contrast, group B recovered normal amino acid levels (glutamine 528 (41.4) micromol/l, histidine 76 (5.3) micromol/l, and total amino acids 2772 (165) micromol/l) (p<0.05 to p<0.001) to give a pattern comparable with that of group A, whereas, in group C, valine and threonine had increased (p<0.05), but glutamine (441 (24.5) micromol/l) and histidine (58 (5.3) micromol/l) remained low. Thus none in group A, two in group B, but ten (53%) in group C still had plasma glutamine levels below 450 micromol/l, including eight of the 11 athletes who had presented with infection. (3) With the additional protein intake, virtually all persisting low glutamine levels increased to above 500 micromol/l. Plasma glutamine rose to 592 (35.1) micromol/l and histidine to 86 (6.0) micromol/l. Total amino acids increased to 2761 (128) micromol/l (p<0.05 to p<0.001) and the amino acid pattern normalised. Six of the ten athletes on this protein intake returned to increased training within the three weeks. CONCLUSION: Analysis of these results provided contrasting plasma amino acid patterns: (a) a normal pattern in those without lasting fatigue; (b) marked but temporary changes in those with acute fatigue; (c) a persistent decrease in plasma amino acids, mainly glutamine, in those with chronic fatigue and infection, for which an inadequate protein intake appeared to be a factor.

Amino Acids↗
PubMed1995

L-arginine increases exhaled nitric oxide in normal human subjects.

1. Endogenous nitric oxide plays an important physiological role and is synthesized by several isoforms of nitric oxide synthase from the semiessential amino acid L-arginine. Nitric oxide is detectable in the exhaled air of normal individuals and may be used to monitor the formation of nitric oxide in the respiratory tract. 2. We have investigated the effect of orally administered L-arginine (0.05, 0.1, 0.2 g/kg) compared with matched placebo on the concentration of nitric oxide in the exhaled air in 23 normal individuals. 3. L-Arginine caused significant increases in the concentration of nitric oxide in exhaled air at doses of 0.1 and 0.2 mg/kg, which was maximal 2 h after administration. This was associated with an increase in the concentration of L-arginine and nitrate in plasma. There were no significant changes in heart rate, blood pressure or forced expiratory volume in 1 s. 4. These results suggest that an increase in the amount of substrate for nitric oxide synthase can increase the formation of endogenous nitric oxide. This may have therapeutic relevance in diseases in which there is defective production of nitric oxide.

Administration, Oral↗
PubMed1995

Prediction of free levels of phenytoin and carbamazepine in patients comedicated with valproic acid.

Serum samples from patients receiving phenytoin (PHT) or carbamazepine (CBZ) and sodium volproate (VPA) polytherapy were filtered at 37 degrees C and the free concentrations were measured by high-performance liquid chromatography. The mean apparent dissociation constants (KD) for the binding of PHT and CBZ to albumin were calculated. The mean KD values were used to predict free levels of PHT or CBZ in serum from patients also taking VPA, based on information about the total serum concentrations of the drugs and albumin. In the presence of VPA the values of the free fraction (alpha) for PHT and CBZ increased and the values for the apparent dissociation constants (KD) decreased compared with the situation of monotherapy. These decreases in the value of KD and increases in the value of alpha were statistically significant. The correlations between values for predicted and analysed free levels of PHT or CBZ were close, with r values of 0.999 and 0.998, respectively. The mean prediction error was small, 0.01 +/- 0.22 mumol/L for PHT and 0.03 +/- 0.42 mumol/L for CBZ. The percentage differences between predicted and observed free levels for PHT and CBZ were < 10%. We conclude that our method of prediction is sufficiently accurate and precise for clinical use.

Adult↗
PubMed1994

The effects of different intravenous feeding regimens on the rates of synthesis of alpha1-antitrypsin after surgery.

The effects of two nutritional regimens on the synthesis of alpha-1 antitrypsin were investigated postoperatively in gynaecological cancer patients. Total parenteral nutrition (TPN) or a hypocaloric amino acid mixture was administered on the day of surgery and continued for 3 days. The rate of synthesis of alpha-1 antitrypsin was estimated by a computer model from serial plasma concentrations of this protein and a reference protein, albumin. The hypocaloric amino acid mixture resulted in a more negative nitrogen balance than that produced during administration of TPN containing the same amount of nitrogen but more non-protein energy. Urinary excretion of 3-methylhistidine was significantly greater (p = 0.017) in the hypocaloric amino acid group (350 +/- 40 mumol/day; mean +/- SE) on the third postoperative day, as compared to the TPN group (240 +/- 20 mumol/day). In spite of this the synthesis of alpha-1 antitrypsin was apparently greater in the hypocaloric amino acid than in the TPN group. The accumulated plasma appearance rate of alpha-1 antitrypsin was significantly higher (p = 0.0465) in HAA group, at 70 h it was 490 +/- 40 compared to 400 +/- 20 times the pre-operative synthesis in the TPN group.

Journal Article↗
PubMed1994

Antiepileptic drug pharmacokinetics and neuropharmacokinetics in individual rats by repetitive withdrawal of blood and cerebrospinal fluid: phenytoin.

The temporal pharmacokinetic (blood) and neuropharmacokinetic (cerebrospinal fluid, CSF) interrelationship of phenytoin was studied after acute and during chronic (up to 5 days) intraperitoneal administration of phenytoin (30, 50 or 100 mg/kg) using a new freely behaving rat model. After administration, phenytoin rapidly appeared in both serum (Tmax mean range 0.15-0.38 h) and CSF (Tmax mean range 0.9-1.4 h), suggesting ready penetration of the blood-brain barrier. However, transport across the blood-brain barrier may be rate limiting since whilst phenytoin concentrations rose dose dependently in serum, CSF concentrations did not. Further, the divergence between the blood and CSF compartments increased with chronic dosing. Cmax, AUC and t1/2 values for serum increased non-linearly, suggestive of accumulation kinetics. Based on these data, high initial phenytoin blood concentrations are essential if phenytoin entry into the brain is to be facilitated, and this may be important in studies of phenytoin in animal models of status epilepticus.

Animals↗
PubMed1994

Indications of changed amino acid homeostasis in untreated and treated PKU.

Amino acid patterns were investigated in children with untreated and treated phenylketonuria (PKU) and compared with a hospitalized paediatric control group. Correlation ratios, i.e. the ratio between the number of statistically significant correlations between pairs of amino acids, were calculated and found to be 0.125, 0.331 and 0.35 in the three groups. Link ratios, i.e. the frequency of statistically significant correlations between a particular amino acid and other amino acids, varied between 0.00 and 0.18, 0.06 and 0.56, and 0.18 and 0.59 in the same groups. Link ratios for especially isoleucine, histidine and arginine were decreased in treated PKU compared to the control group. A reverse nonlinear relationship was established between decreased plasma phenylalanine induced by dietary treatment and increased threonine in plasma. These findings indicate that amino acid homeostasis is disturbed in untreated PKU and not fully normalized in treated patients. The clinical relevance of the findings is unknown.

Amino Acids↗