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Biomedical subjects

M Persson

Publications and source records attributed to M Persson.

At least 37 records · Page 2Linked to original sources
PubMed1994

The association between spontaneous reversal of gingival recession in mandibular incisors and dentofacial changes in children. A 3-year longitudinal study.

In a previous 3-year longitudinal study, reversal of gingival recession in mandibular incisors was observed for 16 out of 28 participating children aged 6-13 years (Andlin-Sobocki et al., 1991). In the present report various dentofacial conditions that might be associated with this reversal were evaluated from dental casts and cephalometric radiographs by comparing the 16 children with spontaneous reversal of gingival recession (Group Rev) to the 12 children with persisting gingival recession (Group Per). Dental casts and cephalometric radiographs were obtained at baseline and after three years. The findings indicate that the children with persisting gingival recession tended to have a particular facial morphology and incisor pattern. They were likely to have a larger basal bone discrepancy between the maxillary and mandibular jaws, with somewhat more proclined and more irregularly positioned mandibular incisors. Although a reduction in incisor irregularity and a slight increase in anterior arch widths occurred for both groups during the observation period, the tooth alignment situation in Group Per at the end of the observation period was similar to that of Group Rev at baseline. Additionally, in Group Rev all facially deviating incisors with recession at baseline had self-corrected at 3 years. This was not the case for Group Per. Thus, spontaneous reversal of gingival recession in mandibular incisors seem to be related to developmental changes in the dentition favouring incisor alignment.

Adolescent↗
PubMed1994

Prospective study of prevalence and endoscopic and histopathologic characteristics of duodenal polyps in patients submitted to upper endoscopy.

BACKGROUND: Retrospective studies of duodenal polyps have shown a prevalence of 0.3%-1.5% in patients referred to upper endoscopy, and histopathologic classifications have been inconsistent. METHODS: A prospective consecutive study was carried out in 584 patients referred to diagnostic upper endoscopy. Symptoms were registered on a questionnaire, endoscopic and histopathologic findings on standard forms. The same pathologist evaluated all biopsy specimens. RESULTS: Twenty-seven patients had polyps in the first and/or second part of the duodenum, for a prevalence 4.6%. Sixteen polyps were either inflammatory (nine polyps) or ectopic gastric mucosa (seven polyps). Both of these polyp types were practically always non-solitary, sessile, small, and located in the duodenal bulb. Seven polyps were covered by normal mucosa, three being endoscopically typical lipomas. Two polyps were adenomas (0.4% of all the patients and 7% of the polyps), and both were found in the descending part. One hyperplastic polyp of the gastric type and one case of fibrosis were found. CONCLUSIONS: 1) Duodenal polyps are found in 4.6% of patients referred to upper endoscopy and should therefore be looked for. 2) Multiple, small polyps in the duodenal bulb are always benign and need neither biopsy nor treatment (in patients with familial polyposis biopsy is recommended). 3) In the descending duodenum polyps are rare, but a substantial number of them are adenomas. Biopsy is therefore mandatory in this localization.

Adenoma↗
PubMed1993

Tracer disequilibrium in CO2 compartments during NaH14CO3 infusion.

The failure of labeled CO2 to equilibrate between extracellular and intracellular CO2 compartments may influence the accuracy of substrate oxidation measurements during infusion of carbon-labeled tracers because it may generate errors in estimate of fixation of labeled CO2 derived from control experiments in which labeled bicarbonate is infused. In this study, normal volunteers received a 14-hour overnight primed continuous infusion of NaH14CO3. Over the last 4 hours of the study, steady-state conditions were achieved in the specific activities (SAs) of expired 14CO2 and plasma urea, which was used as a probe for hepatic intracellular CO2 SA. Plasma urea SA was approximately 17% lower than expired CO2 SA (46.4 +/- 5.6 v 56.8 +/- 3.9 disintegrations per minute.mumol-1, P < .02). Fractional 14CO2 recovery was 94.8% +/- 0.8%; when corrected for failure to equilibrate with intracellular CO2, fractional recovery was 89.5% +/- 1.9%. These data indicate that compartmentalization of CO2 may occur in humans. The duration of our experiments, required because of the long half-life of plasma urea, may have minimized the apparent magnitude of compartmentalization. Furthermore, it is possible that compartmentalization in extrahepatic tissues could be of either lesser or greater magnitude than that which we observed in liver. Whether this phenomenon contributes to incomplete recovery of 14CO2 during NaH14CO3 infusion cannot be determined from our results. Additional studies using different experimental approaches will be required to better measure CO2 compartmentalization.

Adolescent↗
PubMed1993

Metabolism of triacetin-derived acetate in dogs.

Triacetin is a water-soluble triglyceride that may have a role as a parenteral nutrient. In the present study triacetin was administered intravenously to mongrel dogs (n = 10) 2 wk after surgical placement of blood-sampling catheters in the aorta and in the portal, hepatic, renal, and femoral veins. [1-14C]Acetate was infused to allow quantification of organ uptake of acetate as well as systemic turnover and oxidation. Systemic acetate turnover accounted for approximately 70% of triacetin-derived acetate, assuming complete hydrolysis of the triglyceride. Approximately 80% of systemic acetate uptake was rapidly oxidized. Significant acetate uptake was demonstrated in all tissues (liver, 559 +/- 68; intestine, 342 +/- 23; hindlimb, 89 +/- 7; and kidney, 330 +/- 37 mumol/min). In conclusion, during intravenous administration in dogs, the majority of infused triacetin undergoes intravascular hydrolysis, and the majority of the resulting acetate is oxidized. Thus, energy in the form of short-chain fatty acids can be delivered to a resting gut via intravenous infusion of a short-chain triglyceride.

Acetates↗
PubMed1992

Characterization of a recombinant bifunctional enzyme, galactose dehydrogenase/bacterial luciferase, displaying an improved bioluminescence in a three-enzyme system.

The two structural genes encoding galactose dehydrogenase (Pseudomonas fluorescens) and the beta subunit of luciferase (Vibrio harveyi) were fused in-frame in order to prepare and subsequently characterize an artificial bifunctional enzyme complex. This hybrid enzyme exhibited both galactose dehydrogenase activity and bioluminescence when expressed in Escherichia coli together with the alpha subunit of luciferase. The purified conjugate was used to study possible proximity effects in a sequential three-enzyme reaction with the bifunctional enzyme catalyzing the first and the last reaction. The intermediate enzyme, diaphorase, was added separately. The engineered enzyme system, comprising the galactose dehydrogenase/luciferase conjugate, could display a twofold higher bioluminescence in the overall enzyme reaction compared to a corresponding reference system with separate native enzymes. The increased bioluminescence obtained for the engineered enzyme system is proposed to be due to an improved organization of the enzyme in solution.

Dihydrolipoamide Dehydrogenase↗
PubMed1992

Levodopa induced ON-OFF motor fluctuations in Parkinson's disease related to rhythmical masticatory jaw movements.

The motor disturbance in Parkinson's disease affects all voluntary movement, including innate rhythmical processes such as gait, breathing, and chewing. While there are good descriptions and pathophysiological hypotheses of the changes in gait less is known about the way masticatory movements are affected. By means of a three-dimensional optoelectronic recording technique the differences were investigated in mandibular movement displacement, velocity, and masticatory cycle duration during levodopa induced OFF and ON states. Recordings were made before ordinary morning medication and one hour after medication with 200 mg levodopa and a decarboxylase inhibitor (madopar). There were no differences before and after medication in the opening and closing duration of the masticatory cycle, but a significantly decreased occlusal level phase duration in the ON state was seen. Mandibular velocity and mandibular movement amplitude were significantly greater after medication. Thus the changes in dopamine transmission selectively influenced parts of the masticatory cycle but not the fundamental rhythmical pattern.

Administration, Oral↗
PubMed1992

Systemic and regional acetate kinetics in dogs.

Little is known about the sites of production and uptake of acetate in nonruminants. We placed blood sampling catheters in the femoral artery and in the femoral, portal, hepatic, and renal veins of mongrel dogs (n = 11). The animals were studied in the conscious state 2 wk later during a primed continuous infusion of [1-14C]acetate. Systemic acetate turnover, oxidation, and clearance were determined, as well as regional uptake and release, by measuring 14CO2 excretion as well as plasma concentration and specific activity at the five sampling sites. Results showed systemic acetate turnover was 8.8 +/- 1.9 mumol.kg-1.min-1, approximating 5% of energy expenditure in dogs. Simultaneous uptake and release of acetate was demonstrated in intestine, liver, kidney, and hindlimb. The intestine was the greatest contributor to acetate production, whereas the liver was the most important site of uptake. Plasma acetate oxidation was 77 +/- 4% of turnover. Both systemic clearance (129 +/- 22 ml.kg-1.min-1) and tissue fractional extraction (68-85%) were many times greater than values reported for glucose, free fatty acids, lactate, or amino acids. In conclusion, most tissues simultaneously take up and release acetate in dogs. This may represent a mechanism for interorgan transport of energy, especially under conditions of caloric deprivation.

Acetates↗
PubMed1992

Influence of Parkinson's disease on oral health.

Thirty patients with Parkinson's disease were investigated with regard to their oral health. They had significantly more teeth and less caries than a control group of corresponding age. However, the salivary secretion rate was significantly lower with advancing parkinsonian symptoms. It is concluded that not only motor impairment but also autonomic dysfunction, as an expression of a more advanced neuron degeneration, could be of importance when the possibility of maintaining a good oral health in parkinsonian patients is considered.

Activities of Daily Living↗
PubMed1991

Metal affinity precipitation of proteins carrying genetically attached polyhistidine affinity tails.

In this study, galactose dehydrogenase (EC 1.1.1.48) was chosen as a prototype target protein to investigate the capability of metal affinity precipitation to facilitate the purification of genetically engineered proteins. A DNA fragment encoding five histidine residues was fused to the 3'-terminal end of the galactose dehydrogenase gene from Pseudomonas fluorescens and thereafter expressed in Escherichia coli. The additional five histidines functioned as an affinity tail and the modified enzyme could be purified using metal affinity precipitation when the metal-chelate complex with ethylene glycol-bis-(beta-aminoethyl ether) N,N,N',N'-tetra-acetic acid, EGTA(Zn)2, was added to the protein solution. The affinity tail could also be applied for the purification of the fusion protein utilising immobilised metal affinity chromatography. After purification, the pentahistidine affinity tail could be removed enzymatically by carboxypeptidase A. Furthermore, growth rate experiments demonstrated that the expression of the metal-binding affinity tail in E. coli cells enhanced the tolerance to zinc ions when added to the growth medium.

Amino Acid Sequence↗
PubMed1991

Measurement of plasma acetate kinetics using high-performance liquid chromatography.

Previous studies suggest that plasma acetate may be an important fuel in man, accounting for approximately 10% of energy expenditure. Available methods for the determination of plasma acetate kinetics are difficult and time consuming. We describe here a procedure for the determination of plasma acetate concentration and specific activity using automated high-performance liquid chromatography that is precise and sensitive and accommodates large numbers of samples. The procedure involves extraction from plasma with diethyl ether, derivatization with bromoacetophenone, and separation on a C-18 reversed-phase column. The specific activities of D-beta-hydroxybutyrate and lactate can also be determined. Acetate turnover was measured in four dogs and was similar to that previously reported in sheep and humans. Transport of [14C]acetate into red blood cells was negligible.

3-Hydroxybutyric Acid↗
PubMed1991

Continuous regeneration of NAD(H) covalently bound to a cysteine genetically engineered into glucose dehydrogenase.

We introduced a cysteine residue on the surface of glucose dehydrogenase from Bacillus subtilis using site-directed mutagenesis. To this mutant, an NAD-analogue was covalently attached by a disulphide bridge so that it was active intramolecularly. The glucose dehydrogenase-cys44-NAD complex, which contained one reactive NAD molecule per subunit of glucose dehydrogenase, was operated together with lactate dehydrogenase in a coupled enzymatic regeneration of NAD(H) in a hollow fiber reactor. L-lactate and gluconic acid were continuously produced from pyruvate and D-glucose, respectively, with a turnover number of 45 cycles per minute for each NAD molecule. The total turnover per coenzyme was 135,000 for the first 2.5 days.

Bacillus subtilis↗
PubMed1991

Mandibular movement and velocity in relation to state of dentition and age.

Parameters of mastication, such as mandibular displacement, velocity and chewing cycle duration, were investigated in relation to age and rehabilitation with complete dentures. Two groups of elderly subjects (mean age 80 years), one with natural dentition and the other with complete dentures, and one group of young dentate adults (mean age 26 years) participated. Three-dimensional records of masticatory mandibular movements were obtained using the Selspot movement analysis system. There were no differences in the duration of the total or individual components of a chewing cycle, except for the closing phase, which was significantly longer in the complete denture group. Mandibular closing velocity was significantly lower in the two groups of elderly subjects than in the group of young adults. There was a high degree of inter-individual variation in mandibular displacement in all groups, but the mean vertical amplitude was smaller in the elderly groups compared to the group of young adults. For many of the parameters the variation was significantly greater in the groups of elderly subjects than in the younger group. Ageing thus appeared to have a more important effect than the state of the dentition on the parameters studied.

Adult↗
PubMed1991

3-year observations on gingival recession in mandibular incisors in children.

28 children aged 6-13 years, with gingival recession localized to mandibular incisors, were monitored longitudinally to evaluate any changes of the labial periodontal tissues. Measurements included dental plaque, gingival inflammation, gingival recession, probing depth, probing attachment level, keratinized and attached gingiva. Following baseline examination, the incisors were observed at yearly intervals over 3 years. The results showed that a high level of oral hygiene was maintained and that gingival inflammation occurred only to a minor degree throughout the observation period. Gradual reductions in the amount of gingival recession and probing attachment levels took place in all children except for 1 of the subjects with 1 severely malpositioned tooth. Probing depths and widths of keratinized and attached gingiva remained relatively unchanged. The finding that gingival recession in mandibular incisors in young children often improves over time suggests that preventive or reparative treatment in this part of the developing dentition may not be necessary. Decisions about such treatment should be postponed until any spontaneous improvement has taken place.

Adolescent↗
PubMed1991

Salivary levels of mutans streptococci and lactobacilli in dentate 80- and 85-year-old Swedish men and women.

The number of Streptococcus mutans, Streptococcus sobrinus, and lactobacilli in whole stimulated saliva was examined in 130 dentate 80- and 85-yr-old persons. 88.5% were positive for mutans streptococci and 29% carried greater than 10(6) cfu per ml saliva. S. mutans was most frequently isolated and was found in 114 persons (88%) alone or in combination with S. sobrinus. S. sobrinus was detected in 33 persons (25%), who also showed significantly higher salivary numbers of both mutans streptococci and lactobacilli than persons from whom S. sobrinus was not isolated. The S. sobrinus carriers also had significantly lower stimulated saliva secretion rates than the non-carriers. 95% of the subjects had detectable levels of lactobacilli in saliva with 35% having greater than 10(5) cfu per ml saliva. When the subjects were divided into classes according to the number of intermaxillary contacts, i.e. the Eichner classification, the distribution of subjects with high and low salivary counts of cariogenic bacteria varied. Thus fewer subjects belonging to Eichner class A showed higher salivary numbers of mutans streptococci (14% had greater than 10(6) cfu/ml) as well as lactobacilli (21% had greater than 10(5) cfu/ml) than, for example, subjects belonging to Eichner class B (26% had greater than 10(6) cfu/ml of mutans streptococci, 35% had greater than 10(5) cfu/ml of lactobacilli). Subjects who carried a removable denture(s) had significantly higher salivary numbers of both mutans streptococci and lactobacilli than subjects without removable dentures.

Aged↗
PubMed1990

Purification and site-specific immobilization of genetically engineered glucose dehydrogenase on thiopropyl-Sepharose.

The gene encoding glucose dehydrogenase (EC 1.1.1.47) from Bacillus subtilis was inserted in a plasmid 1.0 kb downstream from a lac promoter, resulting in a 70-fold higher production of the enzyme when expressed in Escherichia coli. A glucose dehydrogenase mutant containing a cysteine residue at position 44 could also be expressed at the same high level. This single cysteine residue was used as an 'affinity tag' to simplify the purification procedure as well as for site-specific immobilization of glucose dehydrogenase on Thiopropyl-Sepharose. This enzyme was purified to homogeneity with a final recovery of 65% and a specific activity of 240 U/mg. The oriented immobilization resulted in increased thermal stability.

Affinity Labels↗
PubMed1990

Tensile and shear strength of orthodontic bracket bonding with glass ionomer cement and acrylic resin. An in vitro comparison.

The tensile and shear strength for a polyalkeonate luting cement (AquaCEM) and a no-mix acrylic resin (Unite) in orthodontic bracket bonding were compared in an in vitro test. Brackets bonded/cemented to extracted premolar teeth were subjected to loads in a universal testing apparatus and the dislodging forces were recorded. The possible influences of setting time and of bracket base design were also studied. No significant differences between the cement and the resin were found after allowing 24 hours of setting time. This in contrast to the significantly stronger tensile strength but inferior shear strength for the polyalkeonate cement when stress was applied after 15 minutes. A significantly higher tensile strength value was recorded for a foil-meshed bracket base type compared to an integral base type with cut grooves after 15 minutes, but not after 24 hours. While the polyalkeonate cement adhesion mostly fractured within the cement layer, the acrylic bond more often failed in the enamel-adhesive interface. The results support the use of the fluoride-containing cement as an alternative to acrylic adhesives in orthodontic bracket bonding, especially in high-risk caries patients.

Acrylic Resins↗
PubMed1989

[Whipple's resection in cancer of Vater's ampulla and the pancreatic head].

A review is presented of 62 Whipple's resections between 1962 and 1984 for adenocarcinoma of the choledocho-duodenal junction (CDJ) and pancreatic head (PH). The operation was radical in 17 patients with CDJ (94%) and in 34 patients with PH cancer (77%). The cumulative 5-year survival rates were 22% and 9%, respectively. The overall perioperative mortality was 23%, but was lowered to 11% during the last five years. Histology, size of tumour and age also influenced survival. Sixteen of the 32 radically operated patients who survived more than three months had a period without pain. Whipple's resection is still the only hope for cure in otherwise fit patients with CDJ or PH cancer, estimated to be radically resectable by pre- and peroperative investigations. The operation should be centralized in a few departments.

Adenocarcinoma↗