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Biomedical subjects

T Larsen

Publications and source records attributed to T Larsen.

At least 19 recordsLinked to original sources
PubMed1997

Intrauterine growth correlation to postnatal growth--influence of risk factors and complications in pregnancy.

In a population of 616 pregnant women with increased risk of intrauterine growth retardation, we examined the relationship of third trimester fetal growth to maternal and pregnancy risk factors, the infants condition at birth, and postnatal growth. Intrauterine growth velocity was calculated from repeated estimations of fetal weight using ultrasound. Postnatal growth up to 3 months was measured in 313 of the infants. Intrauterine growth velocity was directly correlated to birth weight deviation (R = 0.35, P < 0.0001) and inversely correlated to postnatal growth (R = 0.21, P = 0.0001). Heavy smoking throughout pregnancy was the most pronounced factor associated with loss of fetal growth percentiles (P = 0.006), and it was also associated with postnatal catchup (P = 0.01). Infants who needed neonatal care had significantly lower intrauterine growth velocities compared to the rest of the study group; no correlation was found between intrauterine growth velocity and Apgar scores or umbilical pH. It is concluded that growth retardation in the third trimester can be identified by ultrasound fetometry, and is associated with maladaptation at birth and postnatal catchup. However, the correlations were weak suggesting that deviation at birth reflects, only to a limited degree, acceleration or deceleration of growth in the third trimester.

Apgar Score↗
PubMed1997

Health services, coordination and the Internet.

The on-going specialization of medical services requires socioeconomic coordination of different health services. The GP is the key to improve this primary coordination. To qualify referral decisions by the GP an Internet-like information system (VisInfo) has been implemented in Denmark. This VisInfo contains information on (1) alternative periods of waiting, (2) medical guidelines for specific treatments (3) clinical home pages, and (4) links to non-medical providers of health services (NGOs). VisInfo was originally implemented in the Counties of Funen, Northern Jutland and Vejle in 1993-1995. A number of other counties are implementing similar information systems whereof the County of Frederiksborg, recently has implemented the first real Internet-system. Provisional experiences with the VisInfo strategy is presented on (1) the general user interest, (2) elaborations of the strategy, and (3) organization. Based on the BlackSeaDiab Action Plan and the BlackSea TeleDiab project, the potential for dissemination of medical informatics in the Black Sea Region through an adaption of the VisInfo strategy is discussed.

Caregivers↗
PubMed1997

Structure, function, and regulation of human cAMP-dependent protein kinases.

A large number of hormones, neurotransmitters, and other signaling substances that bind to G-protein-coupled cell-surface receptors have their signals converge at one sole second messenger, cAMP. The question of how specificity can be maintained in a signal-transduction system in which many extracellular signals leading to a vast array of intracellular responses are all mediated through one second-messenger system has been the subject of thorough investigation and a great deal of speculation. An increasing number of cAK isozymes, consisting of homo- or heterodimers of R subunits (RIalpha, RIbeta, RIIalpha, RIIbeta) with associated catalytic subunits (C alpha, Cbeta, Cgamma), may, at least in part, explain this specificity. The various cAK isozymes display distinct biochemical properties, and the heterogeneous subunits of cAK reveal cell-specific expression and differential regulation at the level of gene transcription, mRNA stability, and protein stability in response to a wide range of hormones and other signaling substances. The existence of a number of anchoring proteins specific to either RIIalpha or RIIbeta, and which localize cAKII isozymes toward distinct substrates at defined subcellular loci, strongly supports the idea that specific functions can be assigned to the various cAK isozymes. The demonstration that selective activation of cAKI is necessary and sufficient for cAMP-mediated inhibition of T-cell proliferation, and the observation that T-cell activation is associated with redistribution and colocalization of cAKI to the TCR, is also compatible with the notion of isozyme-specific effects.

Cloning, Molecular↗
PubMed1997

Evaluation of a new device for sterilizing dental high-speed handpieces.

Dental high-speed turbines and handpieces can take up and expel microorganisms during operation and thus need regular sterilization. This study established a method for validating devices used to sterilize high-speed turbines and handpieces. The air and water channels and turbine chambers were contaminated with suspensions of Streptococcus salivarius or endospores of Bacillus stearothermophilus. The effect of flushing and/or autoclaving performed by a new device combining both procedures was evaluated by counting the number of viable bacteria recovered from these devices. Further, the effect on clinically used handpieces was evaluated. In an initial experiment, the device partially reduced S. salivarius, and the endospores survived. In a second experiment, a 5 to 6 log reduction of S. salivarius in air and water channels was obtained. No growth was observed in clinically used high-speed handpieces, and both S. salivarius and endospores were eliminated from the turbine chambers. Thus, the method of validation proved capable of discriminating between different levels of bacterial reduction.

Air↗
PubMed1997

The energy value of short-chain fatty acids infused into the caecum of pigs.

The present work was undertaken to study the energy value of a mixture of acetic, propionic and butyric acids (0.682:0.226:0.092) infused intracaecally in growing pigs. A basal diet low in fibre (42 g NSP/kg DM) was given at below the requirement for maximum weight gain. In six 2-week periods, N and energy balance measurements in eight growing pigs were carried out with and without infusion of short-chain fatty acids (SCFA). Heat production was measured using open-circuit chambers and the concentration of SCFA in faeces was determined. Less than 1% of the infused SCFA was excreted in faeces illustrating the capacity of the hind-gut to absorb and metabolize SCFA. Infusion of SCFA did not affect the digestibility of nutrients and energy. However, N retention increased demonstrating that SCFA are an energy source for protein gain when pigs are fed at below the requirement of energy. Increased CH4 production together with an increased excretion of branched-chain fatty acids in faeces suggested that there was a higher microbial activity in the hind-gut during infusion. The partial utilization of the infused energy in SCFA was 0.821. A small proportion of the infused energy in SCFA was retained in protein (0.099) and a considerable amount was retained as fat (0.722).

Animals↗
PubMed1997

Improvements in automated PNA synthesis using Boc/Z monomers.

An optimized automated PNA synthesis protocol is reported. Under optimal conditions the product yield of a test 17-mer PNA is approximately 90%. The average coupling yield is 99.4%. The synthesis strategy is Boc/Z and the deprotected amine is neutralized in situ. The monomers are added in molar excess to HATU and pre-activated for 60 s before delivery to the resin. The concentration of the activated monomers is 0.08 M during the couplings. Heteroselective solvation provides the highest coupling yields. Acetic anhydride is used as capping reagent followed by a piperidine wash. The protocol has been developed in a 5 mumol scale but is easily scaled up to 10-50 mumol scale syntheses on the automated synthesizer (ABI 433A).

Biopolymers↗
PubMed1997

Development of resistance to metronidazole and minocycline in vitro.

By local delivery of antibiotics to periodontal pockets, very high initial concentrations are often quickly succeeded by subinhibitory concentrations, which may facilitate development of bacterial resistance. The purpose of the present study was to investigate possible development of resistance in suspected periodontal pathogens after exposure to subinhibitory concentrations of metronidazole and minocycline. The minimal inhibitory concentration (MIC) of 18 reference strains and 12 clinical isolates was determined by a broth dilution method. Subsequently, all strains with MIC < 8 micrograms/ml were exposed to serial passage on plates containing subinhibitory and gradually increasing concentrations of antibiotics, until growth was inhibited. Initially, most strains were inhibited at < or = 0.250 microgram/ml of minocycline and < or = 0.5 microgram/ml of metronidazole, though A. actinomycetemcomitans was resistant to metronidazole. After growth at subinhibitory concentrations, 8 strains survived 1-2 x and 11 stains survived 8-32 x their initial MIC of metronidazole, growing at up to 8 micrograms/ml. All A. actinomycetemcomitans survived 8-64 x their initial MIC of minocycline, growing at > or = 2 micrograms/ml, while all other strains were inhibited at < or = 0.250 microgram/ml, corresponding to a 1-8 x increase in their initial MIC. Thus, development of resistance was observed for periodontal bacteria growing at up to 64 x their initial MIC, but the final level of resistance was moderate.

Aggregatibacter actinomycetemcomitans↗
PubMed1997

A clinical and microbiological study of deep carious lesions during stepwise excavation using long treatment intervals.

Concern about the survival of microorganisms in deep carious lesions may often lead to unnecessary exposure of the pulp during final excavation. There are reasons, therefore, to initiate systematic studies on the alternative procedure known as stepwise excavation. Clinical evaluation of stepwise excavation was performed on 31 deep carious lesions considered to result in pulp perforation by traditional excavation. This study examines the clinical and microbiological alterations during the final excavation performed during long intervals (6-12 months) after the initial treatment that included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. The dentine colour and consistency were assessed by means of standardized scales before application of a Ca(OH)2 compound and a temporary sealing for 6-12 months. Reassessments were performed before the after final excavation. Microbiological dentine samples were obtained in 19 randomly selected lesions by a sterile bur, transferred to and diluted in reduced transport fluid, and plated on tryptic soy agar. After anaerobic incubation at 37 degrees C for 7 days, total colony-forming units per millilitre were counted from (1) peripheral excavated and hard dentine (control), (2) central demineralized dentine before and final excavation, and (3) central dentine after the final excavation. Six samples of central demineralized dentine were without any cultivable flora increasing to 9 samples after the final excavation. The clinical dentine changes occurring during stepwise excavation were characterized by enhanced hardness of the dentine which was associated with a marked reduction in bacterial growth after the final excavation. Despite the presence of bacteria in the excavated dentine none of the carious lesions resulted in pulp perforation, suggesting that the initial removal of the cariogenic biomass appears to be essential for control of caries progression. Stepwise excavation is not only an appropriate treatment of deep carious lesions but is also considered a suitable model for microbiological studies to determine the bacteria persisting in clinically excavated lesions.

Anaerobiosis↗
PubMed1996

[Vesico-amniotic shunt-therapy in fetal obstructive uropathy].

Due to the widespread use of obstetric ultrasound an increasing number of congenital malformations are diagnosed prenatally. Some of these can be treated in utero. A 17 week-old fetus with a posterior urethral valve was diagnosed due to a dilated bladder, bilateral hydronephrosis and oligohydramnios. An ultrasonically guided vesicoamniotic shunt was successfully placed in utero at 24 weeks of gestation in order to prevent development of dysplastic kidneys and hypoplastic lungs. Transurethral valve resection was performed five months postnatally. The one year-old infant is now well and has one normally functioning kidney.

Abnormalities, Multiple↗
PubMed1996

Acute growth hormone injection reduced gastrointestinal and increased hepatic oleic acid oxidation in swine.

Gastrointestinal, hepatic, and hindleg oxidation of 3H-labelled oleic acid and 14C-labelled glucose based on arterial-venous differences in 3H2O and 14CO2 were studied before and after an intravenous injection of 24 IU of growth hormone in 10 piglets. Hepatic oleic acid oxidation increased transiently while gastrointestinal oleic acid oxidation decreased correspondingly, maintaining a constant splanchnic oleic acid oxidation. Administration of a growth hormone led to a transient, parallel decrease in both hepatic and gastrointestinal glucose oxidation. We conclude that, in contrast to the growth hormone effect on splanchnic glucose oxidation, growth hormone effect on splanchnic fat oxidation appears to be organ specific.

Animals↗
PubMed1996

Growth hormone, insulin-like growth factor I and its binding proteins 1 and 3 in last trimester intrauterine growth retardation with increased pulsatility index in the umbilical artery.

OBJECTIVE: The interrelationships between maternal hormone levels and placental dysfunction in mothers bearing children with intrauterine growth retardation remain unclear. We have examined some endocrinological aspects of intrauterine growth retardation and, in particular, tested whether low levels of GH and IGF-I in maternal serum are associated with direct evidence of placental dysfunction. DESIGN: Prospective, descriptive and comparative. PATIENTS: Women with singleton pregnancies: 48 with a small for gestation fetus (SGA) (estimated fetal weight less than -1.5 standard deviation scores) and 28 with an appropriate for gestation fetus (AGA). MEASUREMENTS: Maternal serum GH, IGF-I, IGFBP-1 and 3 were determined, and fetal weight and umbilical artery pulsatility index (PI) was estimated by ultrasonography and Doppler ultrasound at 33 weeks gestational age. RESULTS: Serum IGF-I was lower in the SGA group (246 vs 297 micrograms/l, P = 0.03) but GH and IGFBP-1 and -3 did not differ between the groups. In the 16 SGA pregnancies with increased PI, IGF-I concentration was low (218 micrograms/l, quartiles 149-265), whereas in the 32 with normal PI, IGF-I was 269 micrograms/l, quartiles 219-382. Serum IGFBP-1 was increased in the high PI group compared to the normal PI group (161 micrograms/l vs 113, P = 0.05). CONCLUSION: Maternal serum IGF-I concentration was lower in small for gestational age pregnancies with increased pulsatility of the umbilical artery blood flow, compared to small for gestational age pregnancies with normal umbilical blood flow, which in turn was close to the IGF-I concentration in appropriate for gestational age pregnancies. Growth hormone concentrations did not differ among the groups.

Female↗
PubMed1996

Intrauterine growth curves based on ultrasonically estimated foetal weights.

Available standard intrauterine growth curves based on birthweights underestimate foetal growth in preterm period. New growth curves are presented based on data from four Scandinavian centres for 759 ultrasonically estimated foetal weights in 86 uncomplicated pregnancies. Mean weight of boys exceeded that of girls by 2-3%. A uniform SD value of 12% of the mean weight was adopted for the standard curves as the true SD varied non-systematically between 9.1 and 12.4%. Applied to an unselected population of 8663 singleton births, before 210 days of gestation, 32% of birthweights were classified as small-for-gestational age (SGA; i.e. below mean - 2 SD); the corresponding figures were 11.1% for gestational ages between 210 and 258 days, and 2.6% for ages of 259 days or longer. The new growth curves reveal better the true distribution of SGA foetuses and neonates, and are suggested for use in perinatological practice.

Anthropometry↗
PubMed1996

Resistance of Streptococcus sanguis biofilms to antimicrobial agents.

Bacteria living in biofilms as dental plaque on tooth surfaces are generally more resistant to antimicrobial agents than bacteria in batch culture normally used for in vitro susceptibility testing. In order to compare the resistance of free-living and surface-grown oral bacteria, the MIC of Streptococcus sanguis 804 and ATCC 10556 to amoxicillin, doxycycline and chlorhexidine was determined by a broth dilution method. Subsequently, S. sanguis biofilms established in an in vitro flow model were perfused with the antimicrobial agents for 48 h at concentrations equal to and up to 500 times the MIC, and biofilm cell number was determined during this period. The antibiotics at the MIC did not affect the cell number of S. sanguis biofilms compared to the starting point, and only after 48 h at 500 times the MIC were the biofilm bacteria eliminated. At intermediate concentrations biofilm cell number gradually decreased. Chlorhexidine also gradually reduced biofilm cell number, but was inhibitory at concentrations closer to the MIC than was the case for the antibiotics. Thus S. sanguis in biofilms survived up to 500 times the MIC found in batch culture for up to 48 h.

Amoxicillin↗
PubMed1995

The capsid size-determining protein Sid forms an external scaffold on phage P4 procapsids.

Although the phages P2 and P4 build their capsids from the same precursor, the product of the P2 N gene, the two capsids differ in size: P2 builds a 60 nm, T = 7 capsid from 420 subunits, whereas P4 makes a 45 nm, T = 4 capsid from 240 subunits. This difference leads to substantial changes in shell geometry and subunit interactions. Previous results have demonstrated that the P4 sid gene is responsible for the assembly of P4-sized shells. We have used cryo-electron microscopy and image reconstruction to determine the structure of a putative assembly intermediate of P4 capsids, produced in vivo from cloned genes. We demonstrate that Sid forms a P4-specific scaffold with icosahedral symmetry on the outside of the procapsid-like particles. The Sid molecules (60 or 120 copies) form lofty arches that interact with the gpN hexamers on the icosahedral 2-fold axes, and connect as trimers over the 3-fold axes, forming a continuous dodecahedrally shaped outer cage. The gpN shell inside the Sid cage is approximately 40 nm wide, consistent with the previously suggested maturational expansion. The main difference with respect to the mature P4 capsids is found in the hexamers, which appear strongly elongated and more protruding than in the mature shell. These and previous results are discussed in the light of a model for regulation of capsid size.

Amino Acid Sequence↗
PubMed1995

Prediction of birth weight by ultrasound-estimated fetal weight: a comparison between single and repeated estimates.

OBJECTIVES: Ultrasound estimation of fetal weight is used for diagnosing intrauterine growth retardation. The aim of the present study was to assess the accuracy of birth weight prediction by use of a single or repeated estimations of fetal weight in the third trimester. STUDY DESIGN: 1000 pregnant women considered at risk were scheduled to ultrasound estimation of fetal weight, using Warsof's formula, at 28, 31, 34 and 37 weeks of gestation. The 421 pregnancies with term delivery and complete set of ultrasound examinations and 57 pregnancies with preterm delivery with ultrasound examination at 16 and 28 weeks and once more before delivery were included in the present analysis. RESULTS: The accuracy of birth weight prediction improved significantly for every three weeks from 28 to 37 weeks of gestation in the term infants. Prediction based on the average of repeated weight estimates or linear extrapolation from two estimates or extrapolation by a second order polynomium fitted to four estimates did not improve accuracy compared to prediction based on the last estimate before delivery. CONCLUSION: When more than one ultrasound estimation of fetal weight are available, prediction of birth weight in relation to gestational age should be based on the last ultrasound examination only.

Birth Weight↗
PubMed1995

Parental origin of the X chromosome, X chromosome mosaicism and screening for "hidden" Y chromosome in 45,X Turner syndrome ascertained cytogenetically.

Our study confirms the finding that about 85% of X chromosomes in Turner girls are maternally derived. A new observation is the detection of a high frequency of mosaicism (15%) in Turner girls who by cytogenetic analysis were thought to have a pure 45,X karyotype. DNA examination of the material was done by hybridization with digoxigenin labelled, non-radioactive probes, and PCR products for microsatellite analysis were run on polyacrylamide gels. We screened for the presence of "hidden" Y chromosome mosaicism, using the primers SRY, ZFY, DYZ3, DYZ1 and DYS132. Contrary to other reports using the PCR technique to unravel "hidden" Y chromosome mosaics, we did not find any positive cases. A precise technical protocol for these new techniques is given, and the advantages are discussed.

Chromosome Banding↗