PubMed Health⌕ Search

Biomedical subjects

K Pedersen

Publications and source records attributed to K Pedersen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Microbial growth and accumulation in industrial metal-working fluids.

The dynamics of microbial growth in metal-working fluids (MWF) and the effect of the addition of biocides were studied in large fluid systems, in this case, one central tank which holds 150 m3. In this system, populations of Pseudomonas pseudoalcaligenes (greater than 10(8) CFU/ml) were sustained for a year, although large quantities of biocides were added. Quantitation of 3-OH lauric acid, a marker for many Pseudomonas spp., by gas chromatography indicated that the bacterial biomass exceeded the viable counts by approximately 15 times. Fungi were grown on several occasions, the dominating genera being Fusarium and Candida. Soon after the old MWF was removed and the tank was provided with fresh MWF, which consisted of an emulsion of mineral oil in water, there was a massive growth of P. pseudoalcaligenes that reached levels of greater than 10(8) bacteria per ml. Initially, only low concentrations of other species were found for some weeks. After this period, different enterobacteria and other gram-negative rods often appeared at high concentrations (10(7) and 10(8) bacteria per ml, respectively). Bacteria identified as P. pseudoalcaligenes showed great variation with respect to colony morphology and a certain heterogeneity with respect to biochemical characteristics. Certain bacterial species grew as microcolonies on metal strips immersed in the circulating MWF, but P. pseudoalcaligenes was not recovered from this habitat. The total bacterial count in the air surrounding the machines in the metal-working shop showed an inverse relation to increasing distance from the machine. The concentration of bacteria in the air varied because of the number of machines in use, temperature, and humidity.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Microbiology↗
PubMed1989

Colonization of the porcine gastrointestinal tract by lactobacilli.

Eight strains of lactobacillus isolated from the porcine gastrointestinal tract were tested for their ability to adhere in vitro to cells collected from stratified squamous epithelium in the digestive tracts of newborn piglets. Piglets were inoculated with individual strains, and their digestive tracts were sampled at intervals to determine the colonizing ability of the lactobacilli. The results of the in vitro test did not predict whether a lactobacillus strain would associate with stratified squamous epithelium in the piglet digestive tract, but epithelial association in vivo appeared to be an important factor in the maintenance of lactobacillus populations in the tract. None of the lactobacillus strains used as inocula was numerically dominant in the tract 7 days after inoculation of the piglets with a single dose of the bacteria.

Animals↗
PubMed1989

A neurophysiological study of patients undergoing radical prostatectomy.

24 men suffering from localized prostatic cancer undergoing radical retropubic nerve-sparing prostatectomy were investigated by the following electrophysiological methods: Bulbocavernosus reflexes elicited from the penile skin or the posterior urethra, sensory thresholds in the posterior urethra, cerebral evoked potentials after stimulation of the pudendal nerve or the posterior urethra. 15 men were examined 4-33 months postoperatively only, 5 men were examined only preoperatively and 4 men were examined both pre- and postoperatively. 10 men suffering from minor problems due to benign prostatic hyperplasia served as controls. In patients with localized cancer of the prostate, the findings did not differ from those in the control group. In the operated group the findings were pathological in a large proportion of the patients, indicating injuries both to nervous pathways running through the pelvic nerve plexus and in the pudendal nerve. The conclusions were: Localized cancer of the prostate has minimal or no risk at all of impaired functioning in the pelvic nervous pathways. Radical retropubic prostatectomy may in some cases be undertaken without any objective evidence of injury to these nervous pathways, but is often followed by findings indicating such injury. The dorsal nerve of the penis may be affected by the operation. Transcranial stimulation of the motor cortex is a useful method in the evaluation of prolonged or absent bulbocavernosus reflexes.

Aged↗
PubMed1987

Self-assessment of hearing problems in an elderly population. A longitudinal study.

As part of a large population study, 386 randomly selected probands 70 years of age, representative of the population of an industrialized Swedish city, were questioned regarding hearing difficulties in different social conditions. The same questions were presented to the participants of that study, at the age of 75 and 79 years. The results showed that of the 70-year-old persons, more than 95% had quite a good estimate of their hearing capacity. The subjective hearing problems increased with increasing age. However, at the age of 79 years, 86% still had no hearing problems or had only slight or moderate difficulties. The males reported that they had more hearing problems than the females. The prevalence of irritating tinnitus was about the same for males as for the females (8%). The number of probands with severe tinnitus was constant throughout the investigated period. It is suggested that hearing difficulties experienced when talking to only one person can be used to estimate the need for hearing amplification. A comparison between two cohorts with an age difference of 5 years was made. In a difficult listening situation at the age of 70 years, the hearing of subjects born in 1906-07 was reportedly worse than that of these born in 1901-02.

Aged↗
PubMed1987

Routine synthesis of carbon-11-carboxyl-labeled L-dopa.

Carbon-11-carboxyl-labeled L-dopa has been synthesized by the modified Bucherer-Strecker method. The reaction mixture was first purified by chiral HPLC followed by deprotection using hydriodic acid. The entire procedure was performed in a remotely operated system which gave the product in 28% radiochemical yield (decay corrected) in an overall synthesis time of 55-60 min.

Carbon Radioisotopes↗
PubMed1986

Sequence analysis and characterization of a maize gene encoding a high-sulfur zein protein of Mr 15,000.

We have isolated a gene coding for a sulfur-rich zein protein from a maize genomic library. The nucleotide sequence of this gene predicts a protein composed of 180 amino acids, including a 20-amino acid signal peptide. As is true of other zeins, there are no intervening sequences in the gene. Comparison of the nucleotide sequence of this gene with that of a homologous cDNA clone revealed only a single difference resulting in a valine/alanine substitution. The Mr 15,000 zein contains no repetitive nucleotide sequences and shows no homology with genes encoding the Mr 22,000 and 19,000 zeins. Circular dichroism analysis of the Mr 15,000 zein protein revealed that it is composed primarily of beta and turn structures. This gene has a short region of nucleotide sequence homology to the cysteine-rich domain of the Mr 27,000 zein, as well as the cysteine-containing barley B-hordein.

Amino Acid Sequence↗
PubMed1986

Effects of presbycusis and other types of hearing loss on auditory brainstem responses.

Auditory brainstem responses were studied in 373 healthy individuals of various ages and with sensorineural hearing loss of differing degrees. 209 subjects were elderly and had a hearing loss which included a component of presbycusis. The remainder were young or middle-aged with cochlear hearing loss. Altogether 606 ears were tested. The old individuals had generally longer ABR wave latencies than the young subjects. The I-V interpeak latency (IPL) was also prolonged in the older age groups compared with the group of younger individuals, except for subjects with pronounced hearing loss. The results of the study indicate that an age-related dysfunction of the auditory pathway in the brainstem can be present in presbycusis.

Adult↗
PubMed1985

Brain-stem auditory evoked potentials in different age groups.

Brain-stem auditory potential (BAEP) latencies were measured from individuals with normal or nearly normal hearing. Different age groups were studied separately. Males have 0.1-0.2 msec longer latencies of waves III and V and longer I-V IPLs than females in all age groups. The latencies of waves I, III and V increase 0.1-0.2 msec with increasing age, but the I-V IPL was the same in all age groups. The recognizability was very good for waves I, III and V and fairly good for waves II and IV. There was no interaural time difference.

Adolescent↗
PubMed1984

Auditory brain stem responses in patients with vertigo.

Sixty-two patients with vertigo were examined with ABR. Eight of the 30 patients with vestibular neuronitis had abnormal ABR indicating brain stem dysfunction. Most of the patients with abnormal ABR showed continued ABR abnormality after recovery from the disease. Only one patient with epidemic vertigo had abnormal ABR, the remaining 15 patients had no signs of brain stem involvement. All 16 patients with benign positional vertigo had normal ABR.

Acute Disease↗
PubMed1982

A structural model for maize zein proteins.

With the knowledge of the amino acid sequences of two maize zein proteins (apparent molecular weights of 19,000 and 22,000), a structural model is proposed for their molecular conformation. The circular dichroic spectrum taken in the 190-240 nm range for a zein protein mixture in methanol solution showed the zein secondary structure to be largely helical. The polar, hydrophobic, and turn characteristics of the zein residues, as well as the homologous repeat units in their primary sequences, suggested a structure with nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. Polar residues distributed along the helical surfaces allowed intra- and intermolecular hydrogen bonding such that the zein molecules could be arranged in planes. The proposed glutamine-rich turns located between the helices and at the cylindrical caps would favor side chain interactions resulting in stacking of the molecular planes. Physical properties observed for the zein proteins are explained by the model.

Amino Acid Sequence↗
PubMed1982

Cloning and sequence analysis reveal structural variation among related zein genes in maize.

We have isolated a gene encoding one of the 19,000 dalton zein proteins from a maize genomic library constructed in Charon 4A. This gene occurs on a 7.7 kb Eco RI fragment, and based on Southern hybridization analysis, represents one of several homologous sequences present in the maize genome. The nucleotide sequence of the gene predicts a protein composed of 235 amino acids, including a signal peptide of 21 amino acids. There are no intervening sequences in the gene. By comparing the nucleotide sequence of this gene with that of a homologous cDNA clone, we have identified a basis for microheterogeneity within the gene family. The 5' nucleotide sequences of the genomic and cDNA clones are identical, but they differ in the center of the protein, where repeated amino acid sequences occur. A nucleotide sequence encoding a conserved peptide of 20 amino acids is repeated nine times in the center of both of these clones.

Base Sequence↗