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M Löfgren

Publications and source records attributed to M Löfgren.

13 recordsLinked to original sources
PubMed1992

Some quantitative considerations about DNA adduct enrichment procedures for 32P-postlabelling.

The concentrations of 2'-deoxyribonucleoside-3'-monophosphates remaining in calf-thymus DNA digests after nuclease P1 digestion or extraction into 1-butanol, the most commonly used adduct enrichment procedures prior to the application of the 32P-postlabelling assay, were measured using HPLC and 32P-postlabelling methods. When 10 micrograms of DNA digested to mononucleotides was used, the total amount of nucleotides remaining in the samples were approximately 4 and approximately 14 pmol after nuclease P1 treatment or 1-butanol extraction respectively. The influence of various concentrations of normal nucleotides on the labelling efficiency of a 2'-deoxyguanosine-3'-monophosphate adduct of benzo[a]pyrene diol-epoxide was also studied and found to depend upon the ratio of normal nucleotides/adducted nucleotides present in the sample. Also, the ATP/normal nucleotides ratio in the phosphorylation reaction may affect the quantitation of the adducts and thus deserves due consideration.

1-Butanol↗
PubMed1992

Effects in vitro of progesterone and two 5 alpha-reduced progestins, 5 alpha-pregnane-3,20-dione and 5 alpha-pregnane-3 alpha-ol-20-one, on contracting human myometrium at term.

Progesterone is known to prevent labour at term in domestic animals, but its effect in primates is uncertain. 5 alpha-reduced progesterone metabolites are more potent central nervous system depressants than progesterone is itself. Progesterone and its 5 alpha-reduced metabolites also relax pregnant rat myometrium in vitro. The serum concentration of the initial 5 alpha-reduced metabolite, 5 alpha-pregnane-3,20-dione, is high during pregnancy, but decreases significantly prior to parturition. The next metabolite, 5 alpha-pregnane-3 alpha-ol-20-one, has anaesthetic properties in human beings. The purpose of this study was to ascertain whether these progesterone metabolites also suppress contracting human uterine muscle at term. An in vitro model was devised. Strips of human myometrial muscle were mounted in organ chambers and after regular contractions had become established, the strips were superfused with progestin solutions. The progestins were dissolved in the buffer using an ultrasound bath. Progesterone, used as reference substance, slightly reduced the measured amount of muscular work performed per contraction, recordable after 18 min of exposure (p less than 0.05). Similar results have been reported previously in the literature; 5 alpha-pregnane-3 alpha-ol-20-one showed the same tendency though not significant at the 5% level. 5 alpha-pregnane-3,20-dione evidently reduced the contraction frequency after 10 min of exposure (p less than 0.05). None of the substances affected the duration of the contraction. These 5 alpha-reduced progesterone metabolites are thus not potent inhibitors of contracting human term myometrium in vitro.

5-alpha-Dihydroprogesterone↗
PubMed1992

Progesterone concentrations in maternal and fetal serum are lower during functional dystocia than in normal labor.

Concentrations of progesterone and estradiol (E2) were measured in parturient serum and in fetal cord serum during normal labor and in women with functional dystocia. In the study group, there were no cases of cephalopelvic disproportion. In oxytocin-resistant dystocia, the course of labor could not be corrected with oxytocin. To ascertain the effect of oxytocin, we included a number of women whose labor had been induced with oxytocin, followed by normal cervical dilatation and descent of the fetus. All the parturients were grouped retrospectively into those with normal labor and those with dystocia, based on previous definitions. The serum concentrations of progesterone in both the fetal cord and maternal vein were found to be significantly lower in the oxytocin-resistant dystocia group than in women in spontaneous normal labor and those with oxytocin-induced labor and normal progression (P less than .05-.005). Oxytocin had no evident effect on the serum concentration of either progesterone or E2, nor did concentrations vary following epidural blockade. Serum E2 concentrations in the maternal vein were similar in all delivery groups. Fetal cord E2 serum concentrations were similar in all vaginal deliveries. Women with the most severe oxytocin-resistant dystocia, delivered by cesarean, had significantly lower serum concentrations of E2 in fetal cord serum compared with the vaginally delivered women (P less than .001).

Dystocia↗
PubMed1992

Relation between lightscanning and the histologic and mammographic appearance of malignant breast tumors.

The relation between real-time transillumination (lightscanning) and the histologic appearance of 243 breast carcinomas was evaluated. Lightscanning mainly failed in identifying ductal and lobular carcinomas in situ. The result of lightscanning was also poor regarding small, invasive carcinomas. The absorption patterns in elastosis and scar tissue associated with carcinoma played no important role in the ability of lightscanning to identify a cancer. The relation between the lightscanning and mammographic appearance of 85 breast cancers from the same material was also evaluated. Lightscanning performed poorly in identifying tumors characterized by classifications as compared to tumors with other mammographic appearances. However, the difference was not significant.

Adolescent↗
PubMed1990

Stereotactic fine-needle aspiration for cytologic diagnosis of nonpalpable breast lesions.

Fine-needle aspiration for cytologic diagnosis was performed on 219 nonpalpable breast lesions by using a stereotactic localization technique. Cytologic results were correlated with mammographic findings, and therapeutic decisions were based on the results of both procedures. Representative cytologic material was obtained in 74% of the lesions. Strict criteria of representativeness were observed. If only cases with representative cytologic yield are considered, the sensitivity was 93% and the specificity was 97%. The predictive values were high except for the predictive value of a negative cytologic finding in a spiculated lesion (50%). Sampling errors caused by abundant fibrosis, needle deviation, and difficulty in defining the lesion on the stereoscopic views are discussed. Another source of sampling error may be the mixed nature of some lesions consisting of benign and malignant components. Fine-needle aspiration of 219 nonpalpable breast lesions by using a stereotactic localization device yielded representative cytologic samples in 74% of the lesions.

Biopsy, Needle↗
PubMed1990

Serum concentrations of progesterone and 5 alpha-pregnane-3,20-dione during labor and early post partum.

Serum 5 alpha-pregnane-3,20-dione (5 alpha DHP) and progesterone (P) concentrations were studied in 11 women with uncomplicated pregnancies and deliveries during spontaneous labor and immediately after delivery. Blood samples were drawn 3-6 times during labor, as soon as possible post partum and 1, 3, 6 and 12 h post partum. P and 5 alpha DHP were analysed using RIA methods. There were no significant changes during labor in serum concentration of P and 5 alpha DHP, the values being 366 nmol/l +/- 25 SE and 128 nmol/l +/- 16 SE respectively. Whereas an earlier study has shown a significant decrease in 5 alpha DHP serum concentration between late pregnancy and spontaneous labor, this study showed no decrease during labor, indicating that the decrease occurred before the onset of labor. After parturition, the elimination of P from serum was faster and proportionally greater than for 5 alpha DHP, with a half-life of 38 min for P and 58 min for 5 alpha DHP. About 2-3 h post partum the serum concentrations stabilized just above luteal phase values. 12 h post partum, P and 5 alpha DHP were 12% and 23% respectively of pre-partum values.

5-alpha-Dihydroprogesterone↗
PubMed1988

X-ray guided fine-needle aspiration for the cytologic diagnosis of nonpalpable breast lesions.

X-ray guided localization of 215 nonpalpable, mammographically detected, breast lesions for fine-needle aspiration biopsy was performed using a two-dimensional coordinate grid. Representative material was obtained in 64% of the lesions. Very strict criteria of representativity were observed. The sensitivity of the cytologic procedure was 92%, the specificity 95%, the predictive value of positive cytologic diagnosis 88%, and the predictive value of a negative cytologic diagnosis 97%. Potential pitfalls in the localization and aspiration procedures are discussed. The results of cytologic examination should always be correlated with the mammographic findings, and further diagnostic and therapeutic decisions should be based on both modalities. In this setting, x-ray guided fine-needle aspiration cytologic study is a highly valuable diagnostic tool.

Biopsy, Needle↗
PubMed1988

Decrease in serum concentration of 5 alpha-pregnane-3,20-dione prior to spontaneous labor.

Serum 5 alpha-pregnane-3,20-dione (5 alpha DHP) and progesterone (P) concentrations before spontaneous labor were studied in 13 women whose pregnancy and delivery were uncomplicated. Blood samples were drawn twice weekly from the 36th week of gestation up to the onset of spontaneous labor. P and 5 alpha DHP values were analysed by applying RIA methods. Mean serum 5 alpha DHP concentrations declined significantly during the last week of pregnancy, from 135 +/- 12 nmol/l 5 days prior to spontaneous labor, to 111 +/- 10 nmol/l on the day spontaneous labor started (p less than 0.005). No significant changes in progesterone concentration occurred during the observation period. These results suggest a change in 5 alpha DHP production preceding the onset of spontaneous labor.

5-alpha-Dihydroprogesterone↗