Search PubMed⌕ Search

Biomedical subjects

P Larsson

Publications and source records attributed to P Larsson.

At least 109 records · Page 6Linked to original sources
PubMed1994

F response and H reflex for monitoring nerve block during epidural analgesia with ropivacaine.

The effect of a single epidural injection of ropivacaine on the motor and sensory function controlled from the L5/S1 level was investigated in 28 male volunteers. Concentrations of 1%, 0.75%, or 0.5% ropivacaine, 20 mL, administered at the L2/3 level were studied. Motor function was assessed quantitatively (measurement of muscle force by mechano-transducers), and sensory function by the pinprick method. In addition, F response and H reflex, tests which measure the conduction velocity in the central parts of peripheral nerves, were used. Epidural ropivacaine caused dose-dependent prolongation of the latencies of both these variables. F response latency recovered significantly later than motor function measured by mechano-transducers in the two lower concentration groups. H reflex latency recovered significantly later than sensory function assessed by the pinprick method in all three concentration groups. The time needed for recovery of F and H latencies was not significantly longer than the time from epidural injection to mobilization. At the time when the subjects could go through the mobilization procedure, 12 of 28 subjects were not completely recovered. In 5 of these 12 subjects, the H reflex latency was persistently prolonged at the end of the investigation, long after the subjects felt "normal" again. On follow-up recordings 5 mo later, the baseline latency had been regained in all five subjects. We conclude that F response and H reflex latencies are good indicators of the inhibition of nerve impulse conduction induced by epidural analgesia.

Adult↗
PubMed1994

Proliferation of human renal cell carcinoma studied with in vivo iododeoxyuridine labelling and immunohistochemistry.

Tumor cell proliferation is one interesting cell biological parameter of possible predictive value for prognosis. In the present study 176 tumor and 33 kidney cortex samples from 33 patients with renal cell carcinoma were studied after immunohistochemical detection of in vivo labelled iododeoxyuridine. The tumors had a mean labelling index (LI) of 1.06 +/- 0.59%, significantly different from LI of kidney cortex tissue 0.08 +/- 0.09% (p < 0.001). There was a tendency towards increasing LIs at higher clinical stages. No correlation was found between LI and tumor size. A significant difference existed for LIs between diploid and aneuploid tumors (p = 0.037). Within the limited number of patients with a relatively short follow-up, Kaplan-Meier curves indicated that LI might provide prognostic information.

Adult↗
PubMed1994

Cell proliferation in renal cell carcinoma. A clinical study with special reference to prognosis.

As the clinical behaviour of renal cell carcinoma (RCC) varies considerably from case to case, it is important to identify variables capable of predicting outcome in the individual patient. DNA ploidy status, analyzed by flow cytometry (FCM) in 59 patients with stage I disease, showed survival to be significantly better in the diploid than in the non-diploid subgroup. The prognostic value of S-phase fraction evaluated from DNA histograms (S-FCM) was studied in 69 RCC patients. The mean S-phase value was 7.5%, the values being significantly lower in the diploid than in the aneuploid subgroup. Both in the group as a whole and among patients with aneuploid tumors, survival was significantly better in the low (< 7.5%) than in the high (> or = 7.5%) S-phase fraction subgroup. Multivariate analysis showed both the S-phase fraction and tumor stage to be significant independent prognostic variables. Immunohistochemistry (IHC) studies with in vivo iododeoxyuridine labeling (IdUrd-IHC) performed in a series of 33 RCC patients, showed a mean labelling index (LI) of 1.06%. The LI values being significantly lower in diploid than in aneuploid tumors. In a series of 29 RCC patients cell kinetic studies with in vivo IdUrd labeling and subsequent FCM analysis (IdUrd-FCM), showed a mean tumor LI of 2.7%, and a mean potential tumor doubling time (Tpot) of 20.3 days (kidney cortex samples 137.7 days). Tpot was found to be a significant prognostic indicator, though as intratumor heterogeneity in Tpot was common it needs to be determined in multiple samples. Proliferating cell nuclear antigen (PCNA) expression evaluated by IHC using the monoclonal antibody PC-10 (PCNA-IHC) in 68 RCC patients, showed the mean PCNA index to be 4.9%, and values being significantly greater in aneuploid than in diploid tumors. Both in the group as a whole and among patients with non-metastatic disease, survival was better in the low (< 3.5%) than in the high (> or = 3.5%) PCNA index subgroup. Four different methods of cell proliferation (S-FCM, IdUrd-IHC, IdUrd-FCM, PCNA-IHC) were compared. Comparative analysis according to the Bland and Altman method, showed a good degree of agreement. The results indicated that the different methods seemed to provide comparable information on proliferative activity, although different cell-cycle compartments were monitored.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Tumor-cell proliferation and prognosis in renal-cell carcinoma.

In the present study the prognostic value of tumor S-phase fraction was evaluated in 69 patients with renal-cell carcinoma. The proportion of S-phase cells was calculated from DNA histograms by flow cytometry in multiple samples from each tumor. The mean tumor S-phase percentage varied between 1.0 and 17.0%, mean 7.5%, with a significant difference between diploid and non-diploid tumors. Stage-I tumors showed significantly lower S-phase values than tumors of stages II/III and IV. Histopathological grade correlated with fraction of cells in S-phase. Nineteen tumors were homogeneously diploid, I was tetraploid and 49 were aneuploid. Heterogeneity concerning S-phase values was found in 46 of the 69 tumors and concerning DNA ploidy in 34 tumors. Survival time was longer for patients with diploid tumors than for those with aneuploid tumors. Patients with S-phase values < 7.5% had a longer survival time than patients having tumors with S-phase values > 7.5%. Within the group of aneuploid tumors, patients with S-phase values < 7.5% had a significantly better prognosis. In multivariate analysis, only tumor stage and S-phase gave significant independent prognostic information. The S-phase fraction seems to be an additional prognostic parameter for patients with renal-cell carcinoma.

Adult↗
PubMed1993

Evaluation of amoxicillin clavulanate twice daily versus thrice daily in the treatment of otitis media in children. Danish-Swedish Study Group.

A total of 311 children who had recurrent otitis media or who had experienced failure of initial treatment of acute otitis media with phenoxymethylpenicillin, amoxicillin, ampicillin esters or cefaclor were entered into a single-blind study in two parallel groups in order to compare the clinical efficacy and safety of amoxicillin/clavulanate suspension given b.i.d. or t.i.d. for seven days. The patients were examined prior to the start of treatment, at an early follow-up visit 9 to 12 days after the start of treatment and at a late follow-up visit about three weeks later. Specimens for bacteriological culture were taken from the nasopharynx at entry, at the early follow-up visit, and at the late follow-up visit if there were symptoms of otitis. Both treatment groups showed a similar response, 90% or more of the patients being cured or showing improvement at the time of the early follow-up visit. The initial nasopharyngeal cultures showed growth of Haemophilus influenzae in 53% of the patients, Moraxella catarrhalis in 43% and Streptococcus pneumoniae in 39%. After treatment, cultures showed elimination of the initial pathogens in 30% of patients in both groups and recolonization in 23% in both groups. Haemophilus influenzae was the bacteria most frequently found in the nasopharynx at the first follow-up visit. Adverse effects, which consisted mostly of gastrointestinal and dermatological reactions, tended to be more common in the b.i.d. group but the difference was not statistically significant.

Acute Disease↗
PubMed1993

Use of a DNA hybridization method to verify results of screening for methicillin resistance in staphylococci.

Tests were performed by the disk diffusion method, agar dilution method and the E test to determine the susceptibility to methicillin and oxacillin of clinical isolates and control strains of Staphylococcus aureus (n = 106) and coagulase-negative species (n = 131). Results were compared with those of a dot blot DNA hybridization test, in which the mecA gene was detected using an oligonucleotide probe selected from the mecA gene. Among the Staphylococcus aureus strains the mecA gene was found in all but two strains inhibited by > or = 8 mg/l of methicillin and all but two strains inhibited by > or = 4 mg/l of oxacillin. A disk test using either 1 microgram oxacillin or 10 micrograms methicillin and a tentative resistance breakpoint of < or = 10 mm gave the best agreement with the hybridization test. For coagulase-negative staphylococci 34 of 35 strains inhibited by > or = 8 mg/l methicillin hybridized with the probe as well as 58 of 82 strains inhibited by 1-4 mg/l; 93 of 97 strains inhibited by > or = 0.5 mg/l oxacillin were also positive in the probe test. Using the 1 microgram oxacillin disk and a resistance breakpoint of < or = 10 mm good agreement was obtained between results of the disk diffusion and DNA hybridization tests. It is suggested that this genotypic method for detection of methicillin resistance is used as a reference method for routine methods.

Base Sequence↗
PubMed1993

Distribution and metabolism of aflatoxin B1 in the marmoset monkey (Callithrix jacchus).

Whole-body autoradiography of [3H]aflatoxin B1 (3H-AFB1) in marmoset monkeys (Callithrix jacchus) showed a localization of bound labelling, in addition to the liver, in the nasal olfactory and respiratory mucosa and the mucosa of the nasopharyngeal duct, the pharynx, the larynx, the trachea and the oesophagus. In vitro microautoradiography of these tissues incubated with 3H-AFB1 showed a localization of bound radioactivity in some cells in the epithelial linings of the tissues. This binding was abolished when the incubations were performed in the presence of the cytochrome P-450 inhibitor metyrapone. These results indicate a cytochrome P-450-dependent bioactivation of AFB1 in some structures in the epithelia of the nasal olfactory mucosa and the upper respiratory and alimentary pathways, in addition to the liver, in the marmoset monkey. Quantitation of the in vitro formation of tissue-bound radioactivity from the 3H-AFB1 showed that the nasal olfactory mucosa had the highest capacity to form bound metabolites among the tissues examined. Liquid chromatography of lipid-soluble metabolites formed by the nasal olfactory mucosa and the liver showed that aflatoxin M1 (AFM1) was the major metabolite. AFM1 was also the major metabolite found in the liver in vivo. In the pigmented tissues of the marmosets there was an accumulation of nonmetabolized AFB1. This can be related to a melanin-affinity of AFB1. The described tissues with a capacity to accumulate and metabolize AFB1 may be potential targets for the carcinogenicity of this substance in the marmoset monkey.

Aflatoxin B1↗
PubMed1993

Association of pepsin with type II collagen (CII) breaks control of CII autoimmunity and triggers development of arthritis in rats.

Lewis rats develop arthritis after immunization with heterologous but not homologous rat type II collagen (CII). We have observed that if the rat CII is prepared by pepsin digestion without subsequent extensive purification, it is arthritogenic in Lewis rats. To address whether pepsin in the CII preparations contributed to the development of arthritis and whether this was associated with the induction of an immune response to CII, Lewis rats were immunized with rat CII of various degrees of purity and with various pepsin contents. After immunization with a crude preparation of CII, containing relatively large amounts of pepsin, Lewis rats developed arthritis with an incidence of 80% together with a strong anti-CII autoantibody production. Further purification of the CII on DEAE-Sepharose, which removes pepsin, eliminated the arthritogenic properties and the capacity to activate CII-specific B cells. Likewise, lathyritic CII, prepared without pepsin, induced neither a CII-specific immune response nor arthritis. If, however, pepsin was added to non-arthritogenic batches of rat CII, arthritis appeared at an incidence of 40%. By using an ELISPOT technique to detect antigen-specific interferon-gamma-producing T cells and antibody-producing B cells, the immune response to CII and pepsin can be evaluated. Eleven days after immunization with lathyritic CII and pepsin, a B-cell response towards both CII and pepsin was seen. Pepsin-specific T cells were also seen at day 11, but CII-specific T cells did not appear until day 14 after immunization. In addition, a weak CII-specific proliferative response of the T cells could be demonstrated at day 14 but not at day 11 or 12. These data show that pepsin plays an important role in the triggering of a CII-specific immune response. We suggest a carrier-hapten mechanism where pepsin acts as a carrier and CII as a 'hapten' which will activate CII-specific B cells. Subsequently these CII-specific B cells will break the T-cell tolerance and evoke a T-cell-mediated immune response towards CII.

Animals↗
PubMed1993

Blockade of the abdominal muscles measured by EMG during lumbar epidural analgesia with ropivacaine--a double-blind study.

A single shot of 20 ml of 1%, 0.75% or 0.5% ropivacaine was administered epidurally (at L2/3 level) to 30 volunteers, in a double-blind manner. The blockade of the rectus abdominis muscle was measured quantitatively by registration of the average rectified electromyographic signal (AREMG) at the T7, T9 and T11 motor segmental levels and with a qualitative test for blockade of the rectus abdominis muscle (the so-called RAM test). The maximal cranial spread of analgesia, evaluated by the pin-prick method, was not significantly different for the three concentrations (T8-T10 dermatome; median value). The intensity of motor blockade, measured by the AREMG method, increased progressively from the T7 segment and caudally with all three concentrations. The blockade was partial (i.e. 85-25% of baseline AREMG activity was present at its maximum) in all subjects. When the effect of the three concentrations of ropivacaine was compared at the same segmental level, the intensity and duration of maximal motor blockade seemed to be dose-dependent, but the difference was not statistically significant. The total duration of motor blockade was shorter with the 0.5% solution than with the higher concentrations. The AREMG method gave a more exact and graded picture of blockade of the rectus abdominis muscle than the RAM test. The duration of sensory blockade did not outlast motor blockade at any level. In half of our subjects the maximal spread of sensory blockade was either equal to or higher than the spread of partial motor block. In the other half, this relationship was reversed--the maximal cranial level of partial motor block was 1-4 segments higher than the maximal level of analgesia.

Abdominal Muscles↗
PubMed1993

Influence of Escherichia coli on urease-induced crystallisation in human urine.

Urease was added to urines inoculated with Escherichia coli 24 hours earlier and to control urines not inoculated with E. coli. The inoculation did not change the concentration of the measured urine components. The urease-induced ammonium ion production and pH increase was reduced in E. coli-inoculated urines compared to control urines. This suggests that E. coli can inhibit urease. The precipitation of both phosphate and magnesium on glass rods inserted in the urine was reduced with 40-50% in the E. coli-inoculated urines. The results demonstrate that E. coli can influence urease-induced crystallisation.

Adult↗
PubMed1992

Binding of aflatoxin B1 metabolites in extrahepatic tissues in fetal and infant mice and in adult mice with depleted glutathione levels.

Whole-body autoradiography of 3H-labeled aflatoxin B1 (AFB1) in adult C57BL mice pretreated with the glutathione (GSH)-depleting agent phorone showed accumulation of tissue-bound radioactivity in the nasal olfactory and respiratory mucosa, the mucosa of the nasopharyngeal duct, and the tracheal and esophageal mucosa, which was not seen in unpretreated adult mice. The altered distribution pictures induced by the phorone are probably related to decreased tissue levels of GSH. The AFB1 is likely to be bioactivated locally in the extrahepatic tissues; in nonpretreated mice the reactive AFB1 metabolite formed is probably scavenged by GSH via the action of glutathione-S-transferase, whereas in the mice with depleted GSH levels a binding to tissue macromolecules will instead take place. The mechanism indicated above is supported by results of in vitro experiments in which the nasal olfactory mucosa and the esophageal mucosa were shown to have a capacity to form tissue-bound 3H-AFB1 metabolites. This formation was decreased when the incubations were performed in the presence of GSH. In addition, the treatments of mice with phorone were shown to induce a strong GSH depletion in the nasal olfactory mucosa and the esophageal mucosa. In autoradiographic studies performed with 1- and 5-day-old infant mice a marked localization of bound 3H-AFB1 metabolites was found in the nasal olfactory mucosa, and in the 5-day-old infant there was also a labeling of the mucosa of the nasopharyngeal duct, the pharyngeal and esophageal mucosa, and the tracheal mucosa. Experiments in vitro with the nasal olfactory mucosa of 5-day-old infants demonstrated a marked binding of 3H-AFB1 metabolites in this tissue. Incubations together with GSH decreased this binding, although the inhibition was less marked than in the adult animal. The in vivo accumulation of bound AFB1 metabolites in the extrahepatic tissues of the infant mice may be related to low glutathione-S-transferase (GST) activity in the tissues of the young animals. In addition, some extrahepatic tissues may have a considerable capacity to bioactivate the AFB1 at early age. Autoradiography of 3H-AFB1 in pregnant mice showed a labeling of the fetal nasal olfactory mucosa at day 18 but not at day 14 of gestation. This indicates that AFB1-bioactivating enzymes develop in the fetal nasal olfactory mucosa in late gestation.

Aflatoxin B1↗
PubMed1992

Bioactivation of aflatoxin B1 in the bovine olfactory mucosa: DNA binding, mutagenicity and induction of sister chromatid exchanges.

Nasal olfactory tumours occur in cattle in relatively high frequencies in several developing countries. Since affected animals sometimes show signs of severe aflatoxicosis, a role of aflatoxin B1 (AFB1) in tumorigenesis can be proposed. The results of the present study show that microsomal preparations of the bovine olfactory mucosa have a much higher ability than liver microsomes to induce covalent binding of AFB1 to calf thymus DNA and to microsomal proteins. The major DNA adduct formed was 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B1. Incubations of microsomal preparations of the bovine nasal olfactory mucosa with glutathione (GSH) and cytosolic fractions of the nasal mucosa resulted in decreased AFB1 DNA binding. A more pronounced decrease was observed when cytosolic fractions of mouse liver were added to the incubations. Mouse liver is known to contain a glutathione-S-transferase with a high ability to scavenge the reactive AFB1-epoxide via conjugation to GSH. Our results indicate that AFB1-GSH conjugation occurs less efficiently in the bovine nasal olfactory mucosa than in the mouse liver. Supernatant preparations (9000 g) of the bovine nasal olfactory mucosa incubated with AFB1 were shown to have the capacity to induce a strong genotoxic response both as regards induction of gene mutations in Salmonella typhimurium TA100 and the induction of sister chromatid exchanges in Chinese hamster ovary cells. Preparations of the bovine liver (9000 g) has a much lower ability to induce these effects. The results of the present study show that the bovine nasal olfactory mucosa has a high AFB1-bioactivating capacity, which can be related to the potent DNA damaging and mutagenic effects observed. It is considered that our results support the assumption that AFB1 plays a role in the aetiology of nasal tumours in cattle.

Aflatoxin B1↗
PubMed1992

Extrahepatic disposition of 3H-aflatoxin B1 in the rainbow trout (Oncorhynchus mykiss).

Whole-body autoradiography in rainbow trout (Oncorhynchus mykiss) after oral and intravenous administration of 3H-labelled aflatoxin B1 showed labelling of several extrahepatic tissues, such as the uveal melanin and the vitreous humour of the eyes, the trunk and head kidney, the olfactory rosettes and the pyloric caecae. Liquid chromatography of extracts of the vitreous humour showed that unmetabolized 3H-AFB1 was the main labelled material present at this site. Liquid chromatography of extracts of the uveal melanin showed presence of aflatoxicol and aflatoxin B1 in proportions of about 3:1. The binding to the pigment is probably due to a hydrophobic type of interaction with the melanin. Microautoradiography showed that melanin-containing cells in the trunk and head kidney and in the olfactory rosettes also accumulated high amounts of radioactivity. In the trunk kidney there was, in addition, a labelling of the second segment of the proximal tubules and of the distal tubules and the collecting ducts. Studies in vitro with microsomal and 12,000 x g supernatant preparations of the trunk kidney showed formation of DNA- and protein-bound metabolites from the aflatoxin B1. It is probable that the bioactivation of the aflatoxin B1 is confined to the cytoplasm of the cells, may be related to excretion and/or absorption processes. Microautoradiography of the olfactory rosettes, showed labelling of the sensory epithelium, but not the indifferent epithelium. A low formation of protein-bound aflatoxin B1-metabolites was found in incubations with microsomal preparations of this tissue. The same observation was made in incubations with microsomal preparations of the head kidney. In the pyloric caeca bound metabolites were observed in vivo at a level comparable to that found in the trunk kidney. Our results suggest that retention and metabolism in some extrahepatic tissues might be of importance as concerns the toxicologic potential of aflatoxin B1 in the rainbow trout.

Aflatoxin B1↗
PubMed1991

Interaction of P-fimbriated Escherichia coli with human meconium.

The ability of Escherichia coli with different receptor specificities to interact with meconium was studied. E. coli strains expressing P-fimbriae, specific for Gal alpha 1-4Gal beta-containing receptors, were agglutinated by meconium at high titres. This reaction was inhibited by globotetraosylceramide. The attachment of P-fimbriated E. coli to human colonic epithelial cells of the HT-29 cell line was inhibited by meconium. Some type 1 fimbriated strains were agglutinated by meconium, but the agglutination was rarely blocked by methyl alpha-D-mannoside. The attachment by type 1 fimbriated strains to HT-29 cells was reduced by meconium only in some cases. These results suggest that meconium interacts with the P-fimbriae of E. coli, in a way that may influence bacterial colonization of the neonatal intestine.

Adhesins, Escherichia coli↗