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Biomedical subjects

J Pedersen

Publications and source records attributed to J Pedersen.

At least 73 records · Page 4Linked to original sources
PubMed1996

Genetic speciation of Candida isolates by arbitrarily primed polymerase chain reaction.

Candida species are opportunistic human pathogens capable of causing a variety of clinical diseases. Rapid and precise identification of Candida to species level is essential for effective treatment and management strategies. Conventional diagnosis of candidiasis is sometimes slow and variable. By using a random primer 5'-ACGGGCCAGT-3' in arbitrarily primed polymerase chain reaction, seven common Candida species (i.e., C. albicans, C. guilliermondii, C. parapsilosis, C. krusei, C. lipolytica, C. tropicalis and C. (Torulopsis) glabrata) produced characteristic DNA band patterns, which enabled rapid determination to species level among them. Further analysis of the nucleotide sequences of Candida specific fragments should improve our understanding of the molecular structures and possible functions of the gene regions involved.

Candida↗
PubMed1996

Ensemble coding of muscle stretches in afferent populations containing different types of muscle afferents.

Ensemble coding of simple mechanical stimuli (small sinusoidal stretches) was studied in simultaneously recorded mixed ensembles of primary- and secondary muscle spindle afferents (MSAs), and Golgi tendon organ (GTO) afferents recorded from L7-S1 dorsal root filaments. The experiments were made on 48 recorded afferents (29 primary MSAs, 6 secondary MSAs and 13 GTO afferents) in chloralose anaesthetised cats. For the analyses, we used a combination of principal component analysis and algorithms for quantification of stimulus discrimination. Mixed ensembles of primary- and secondary MSAs, and GTO afferents, discriminated significantly better between different muscle stretches than ensembles of only one or two types of these afferents. All kinds of ensembles showed a successive increase in discriminative ability with increased ensemble size and this ability seemed to level at larger populations. However, the increase in discriminative ability was significantly greater for the mixed ensembles. It is hypothesised that the main reason for the greater discriminative ability achieved by mixed ensembles, might be that the variation in response profiles (sensitivity tuning) among the individual afferents of the mixed ensemble will be larger than that for ensembles of only one type of afferent. Finally, the results in the present study give experimental support to some of the teleological arguments in favour of the ensemble coding theory.

Animals↗
PubMed1996

Use of arbitrarily primed polymerase chain reaction to differentiate Trichophyton dermatophytes.

Dermatophytes such as Trichophyton species are common human pathogens, the infection of which results in dermatophytosis (also known as ringworm). Several laboratory tests are used routinely for the diagnosis of dermatophytosis, but they are either slow or lacking specificity. Through examination of genomic DNA from Trichophyton dermatophytes and other fungi in arbitrarily primed PCR, it was shown that a random primer 5'-ACCCGACCTG-3' produced bands of 4.3 kb, 1.9 kb, 1.7 kb and 0.7 kb in T. rubrum DNA, bands of 2.5 kb, 1.9 kb and 0.8 kb in T. mentagrophytes var. interdigitale and T. mentagrophytes var. mentagrophytes DNA, and bands of 2.5 kb, 1.9 kb, 1.5 kb and 0.9 kb in T. tonsurans DNA. This primer amplified bands of different sizes in other fungal DNA. Therefore, based on the distinct band patterns observed in arbitrarily primed PCR using this primer, T. rubrum, T. mentagrophytes and T. tonsurans dermatophytes could be rapidly differentiated.

DNA Primers↗
PubMed1996

A neural network approach to real-time spike discrimination during simultaneous recording from several multi-unit nerve filaments.

A multi-channel, real-time, unsupervised spike discriminator was developed in order to reconstruct single spike trains from several simultaneously recorded multi-unit nerve filaments. The program uses a Self Organising Map (SOM) algorithm for the classification of the spikes. In contrast to previous similar techniques, the described method is made for use on a PC, and the method may thus be implemented at relatively low cost. In order to test the accuracy of the program, a robustness test was performed, where noise with different RMS levels was superimposed on the spikes. Furthermore, the maximal classification rate was determined. The program is easy to use, since the only manual inputs needed are the voltage threshold for spike detection, and the number of units present in each recorded nerve filament.

Action Potentials↗
PubMed1996

Long-term ganciclovir chemotherapy for congenital duck hepatitis B virus infection in vivo: effect on intrahepatic-viral DNA, RNA, and protein expression.

Long-term antiviral chemotherapy using the nucleoside analogue ganciclovir was undertaken with the aim of eliminating hepadnaviral covalently closed circular (CCC) DNA from the livers of ducks that were congenitally infected with the duck hepatitis B virus (DHBV). Twenty-four weeks of ganciclovir therapy caused a substantial reduction in viremia, intrahepatic viral DNA replicative intermediates, and viral core proteins. Unfortunately, ganciclovir therapy did not substantially affect CCC DNA or viral RNA levels, and the treatment resulted in an increase in the intrahepatic expression of the viral envelope proteins, pre-S and S. By the completion of therapy, the viral envelope proteins had assembled into large aggregates within the cytoplasm of most hepatocytes. Viral replication in the bile duct epithelial cells and in the extrahepatic sites was likewise not affected by long-term ganciclovir therapy. In conclusion, 24 weeks of ganciclovir therapy decreased most viral replication markers within the liver, except for those of viral CCC DNA, RNA, and envelope proteins. Long-term therapeutic strategies using nucleoside analogs such as ganciclovir should be used with caution in chronic hepatitis B virus (HBV) infection. The careful monitoring of serum and hepatic markers of viral replication may therefore be important to avoid possible toxic consequences, such as the selective accumulation of viral proteins.

Animals↗
PubMed1996

Percutaneous dilatational tracheostomy.

METHODS: Fifteen patients electively selected for percutaneous dilatational tracheostomy as performed with the Ciaglia Percutaneous Tracheostomy Introducer Set are reported in this preliminary study. RESULTS: The median time for insertion of the tracheostomy tube was 13.9 min. Complications were cuff puncture of the translaryngeal tube at an early stage of the procedure in one case, and minor bleeding controllable by the compressible effect of the dilatational procedure in three cases. During the posttracheostomy period, complications were one case of minor bleeding controllable by digital compression and one case of minor infection, i.e. cellulitis in a few millimetres around the stoma without purulent secretion. CONCLUSIONS: Our preliminary results indicate the technique as performed with the Ciaglia Introducer Set to be effective and safe with only minor complications. Furthermore, we now use it as a bedside procedure in the ICU, thus avoiding the transportation of critically ill patients to the operating theatre. The conclusion of the superiority of percutaneous tracheostomy to dissectional tracheostomy has to await clinical randomized studies, including more patients.

Adolescent↗
PubMed1996

Fertility after autotransposition of vas: a comparative study of absorbable and nonabsorbable suture material in rats.

The anastomosis patency after autotransposition of vas (ATV) using an absorbable and a nonabsorbable suture material (10-0 Vicryl vs Ethilon) and the fertility have been investigated in a rat model. The patency rate and fertility in the absorbable group were 84% and 48%, respectively, compared with 93% and 59% in the nonabsorbable group. Sperm granulomas occurred in 60% and 48%, respectively. Sperm antibodies were present in 36% of the cases but did not have an impact on the fertility. The fertility after ATV seems to be comparable to the fertility in experimental and clinical vasovasostomy series. Further, the two suture materials appear equivalent with respect to patency and fertility in ATV.

Animals↗
PubMed1995

The role of the gamma-system for improving information transmission in populations of Ia afferents.

Ensemble coding of simple mechanical stimuli (small sinusoidal stretches) was studied in populations of simultaneously recorded primary muscle spindle afferents (MSAs). The experiments were made on 39 primary MSAs in chloralose anaesthetised cats. For the analyses we used a combination of principal component analysis and algorithms for quantification of stimulus discrimination. Ensembles of primary MSAs discriminated better between different muscle stretches than individuals, and showed a successive increase in discriminative ability with increasing ensemble size. The ensemble effect disappeared after cutting the ventral roots, indicating an important role for the fusimotor system in ensemble coding. Simultaneously recorded ensembles of MSAs showed significantly better discriminative ability than pooled sequentially recorded MSAs. This difference was abolished by the cutting of the ventral roots. It is hypothesised that, since the muscle spindles are connected to each other via secondary MSAs (projecting to gamma-motoneurones to other spindles), the fusimotor-muscle spindle system may constitute a neural network, in which each 'neuron' (i.e., each individual muscle spindle) is influenced by the activity in the whole network. In populations of pooled sequentially recorded MSAs, the connections would not exist. Thus, the population would lose its neural network quality, and the encoding ability of the population would decrease.

Afferent Pathways↗
PubMed1995

p53 and Rb immunostaining in locally advanced bladder cancer: relation to prognostic variables and predictive value for the local response to radical radiotherapy.

The association between known prognostic variables and altered immunostaining for the nuclear proteins retinoblastoma (Rb) and p53 was studied in a homogeneous series of locally advanced bladder cancer. The predictive value of this immunostaining for the local response to intended radical radiotherapy was investigated. Among 262 patients treated with intended radical radiotherapy between 1967 and 1986, a total of 154 patients were evaluable with respect to local response to treatment. The paraffin-embedded specimen from the tumour prior to irradiation was immunostained with the monoclonal antibodies PMG3-245 for Rb and 1801 for p53 nuclear proteins after heating in a microwave oven for 40 min at 650 W. An altered expression of Rb and p53 was observed in 18 and 42% of the tumours, respectively. p53 overexpression was associated with higher tumour grade. However, the results of the p53 and Rb immunostaining procedures had no predictive value for tumor response to radiation treatment, local control or cancer-specific mortality.

Adult↗
PubMed1995

Experimental vas replacement by either vas or a vascular graft.

An experimental model for vas replacement by transplantation of either vas or a vascular graft in attempt to restore patency in cases of a substance loss of vas that cannot be overcome by vasovasostomy was developed. Three transplant lengths, representing 10, 20 and 30% of the entire vas length, were used. The results showed an overall patency of 43% but for the transplant length representing 10% of the vas patency was achieved in approximately 75% of the cases regardless of the type of transplant used. Unpatency was usually due to occlusion of the proximal anastomosis, which in turn was considered to be due to a combination of unfavourable nutritional, neural and surgical factors. It is concluded that vas replacement by transplantation using either vas or a vascular graft is possible to perform experimentally and gives acceptable patency rates up to a transplant length of 10% of the entire vas length.

Animals↗
PubMed1995

[Serratia marcescens nucleases. I. Comparison of native and recombinant nucleases using electrospray mass spectrometry].

Isoforms of the natural and recombinant nucleases of Serratia marcescens were characterized by their molecular mass, which was determined by electrospray mass spectrometry. The natural nuclease was isolated from the S. marcescens B10M1 culture, whereas the recombinant nuclease was obtained from Escherichia coli MT102 cells carrying plasmid p403-SD2 with the nuclease gene nuc. The primary structure for each of the isoforms isolated from the nuclease preparations was determined by comparing its molecular mass with that of known amino acid sequence, which was determined from the nucleotide sequence of the nuc gene. Both preparations included identical nuclease variants with N-terminal amino acid residues removed. The number of isoforms in the natural nuclease was, however, significantly greater than in the recombinant nuclease. The structures of some of the isoforms were confirmed by N-terminal analysis.

Chromatography, DEAE-Cellulose↗
PubMed1995

[Serratia marcescens nucleases. II. Primary structure analysis by peptide mapping combined with plasma-desorption mass spectrometry].

The primary structures of nucleases Sm1, Sm2, and Sm3 produced by Serratia marcescens were completely characterized using plasma desorption mass spectrometry (PDMS) of proteolytic peptides isolated by reverse-phase HPLC. The isoforms were separated by anion-exchange chromatography on DEAE cellulose and subjected to hydrolysis by the lysine-specific endoproteinase Lys-C. Comparative analysis of the peptides identified by PDMS showed that all three nucleases are N-terminal variants of the same protein: Sm2 represents a "mature" protein form, whereas Sm1 and Sm3 lack three and one N-terminal amino acid residues, respectively.

Amino Acid Sequence↗
PubMed1995

[Nuclease isoforms of natural and recombinant strains of Serratia marcescens. Comparative characteristics of plasma desorption mass spectrometry].

The primary structure of isoforms of natural nuclease secreted by Serratia marcescens as well as of recombinant nuclease produced by Escherichia coli has been characterized by plasma desorption mass spectrometry. The isoforms were isolated from the purified nuclease on a DEAE-cellulose anion-exchange column and digested with endoproteinase Lys-C. The peptides generated were isolated by reversed phase IIPLC and their molecular masses determined by plasma desorption mass spectrometry. Among the nuclease isoforms secreted by parent cells, a new isoform, Sm3, was found. Comparison of the peptides yielded by nuclease Sm2 and two isoenzymes, Sm1 and Sm3, demonstrated their distinction only in the N-termini; three amino acids are lacking in Sm1 and one residue in Sm3. Identity was demonstrated between nucleases Sm1 and Sm2 produced by S. marcescens and the isoforms rSm1 and rSm2 secreted by the recombinant E. coli strain.

Amino Acid Sequence↗
PubMed1995

[Characteristics of isoforms of Serratia marcescens from electrospray mass spectrometry].

Electrospray mass spectrometry was used to determine the molecular masses of nuclease isoforms isolated and purified from the cultural fluid of Serratia marcescens B10M1. The primary structure of each of the isoforms isolated from the nuclease preparations was established by comparing their masses with the known amino acid sequence encoded by the nuc-gene. The structure of some of these isoforms was verified by N-terminal sequencing, that of nearly all isoforms-by isoelectric focusing. All nuclease isoforms were found to be variants of native nuclease split at the molecular N-termini.

Chromatography, DEAE-Cellulose↗
PubMed1994

[Complications and late sequelae after nasotracheal intubation].

A total of 379 patients admitted to the Intensive Care Unit (ICU) for mechanical ventilation were prospectively investigated for lesions of the nose, nasal cavity, ears and larynx during and after nasotracheal intubation. One to two years later, the surviving patients were questioned to investigate late persisting sequelae. During intubation and up to five days following extubation, inflammatory changes and ulceration of the nostrils or nasal septum were found in respectively 76 (20%) and 110 (29%) patients. There were bleedings from the nasal cavity in 67 (19%) and fractures of the conchae in 40 patients (11%). Hoarseness was noted in 135 patients (42%). Inflammatory changes and ulcerations of the nostril and nasal septum were correlated to the duration of intubation. Among the 281 patients included in the follow-up study, 100 (35%) had symptoms from the nose and nasal cavity. Sixty-five (24%) had symptoms related to the ears, 56 (20%) to the maxillary sinus, 81 (29%) to the voice and 90 (32%) to the throat. Increasing duration of intubation was found to be correlated to persisting symptoms from the larynx. Former ulcerations of the nose were associated with a tendency toward nasal bleeding. To avoid as many complications as possible from the nose and nasal cavity, we recommend orotracheal intubation. As late sequelae from the larynx increase with the duration of intubation, perhaps tracheostomy should be performed earlier than is general practice today, but that has to be proven in forthcoming studies.

Adolescent↗
PubMed1994

Problems and pitfalls in the use of estimated age in anthropometric measurements of children from 6 to 60 months of age: a case from Mali.

Estimates of the age of children are often used uncritically in anthropometric measures. This study shows that even with construction of calendars for use of determination of age, substantial training, a careful follow-up in the field by research assistants, and control of all questionnaires immediately after the interviews of the caretakers and weighing of the children, errors remain in estimating the age of children. Such errors may affect the results substantially, leading to errors in the estimation of age-based measures of nutritional status. In the case of Northern Mali, the effect was most likely an underestimation of malnutrition by perhaps as much as 10 to 30 percentage points. The biases in age estimation in many cases are not constant across subgroups of a population. Therefore age estimation problems may lead to wrong decisions regarding policy formulation, planning of development programs and activities, identification of target groups, and, in particular, evaluation of programs and activities. In situations where age has to be estimated, anthropometric measurements that are less influenced by errors in age estimation are recommended.

Age Factors↗
PubMed1994

Extent of blood transfusion and cancer-related mortality after cystectomy and urinary diversion for bladder cancer.

OBJECTIVE: To assess the possible adverse effect of peri-operative blood transfusion on cancer-related survival after radical cystectomy for bladder cancer. PATIENTS AND METHODS: The hospital records of 130 patients treated with cystectomy and urinary diversion for bladder cancer between 1967 and 1986 were retrospectively reviewed. RESULTS: Standard proportional hazards estimation revealed tumour stage and radiation response after pre-operative irradiation to be significantly associated with cancer-related mortality, whereas age, tumour grade or the extent of peri-operative blood transfusion were not. In models which allowed time varying effects a significantly changed effect of blood transfusion (> or = 7 versus < or = 6 units) was observed, from an initially insignificantly increased relative hazard (RH) (RH = 1.44 at 6 months) to an insignificantly decreased effect after longer follow-up (RH = 0.53 after 2 years). CONCLUSION: Although no overall association between blood transfusion and cancer-related mortality was found, a tendency towards an increased risk early in the follow-up period was observed if more than 6 units were transfused. However, these results need confirmation in further studies before a restrictive attitude towards peri-operative blood transfusion is recommended.

Adult↗