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Biomedical subjects

S Lundgren

Publications and source records attributed to S Lundgren.

At least 55 records · Page 3Linked to original sources
PubMed1994

A protein involved in calcium sensing of the human parathyroid and placental cytotrophoblast cells belongs to the LDL-receptor protein superfamily.

Monoclonal anti-parathyroid antibodies have been utilized to isolate a single-chain glycoprotein of 500 kDa, which apparently acts as a sensor of the extracellular calcium concentration and is expressed on the surface of human parathyroid, placental, and kidney tubule cells. The present contribution reports the isolation of a cDNA clone encoding this protein in human placenta and subsequent Northern blots confirming the mRNA expression also in human parathyroid and kidney cells. Close similarity in sequence as well as in tissue distribution is demonstrated with the rat Heymann nephritis antigen, a kidney tubule glycoprotein with calcium-binding ability. The 500-kDa protein belongs to the LDL-receptor superfamily of glycoproteins, claimed to function primarily as protein receptors and characterized by functionally important calcium-binding capacity. It is proposed that the currently identified protein constitutes part of a common structure for the sensing of extracellular calcium concentrations and influences calcium homeostasis in different organs.

Base Sequence↗
PubMed1994

Weekly doxorubicin with or without high-dose medroxyprogesterone acetate in hormone-resistant advanced breast cancer. A randomised study. The Norwegian Breast Cancer Group.

In a randomised study, 218 patients with advanced breast cancer, resistant to hormone therapy, received either doxorubicin 20 mg every week (Awkly) alone or Awkly combined with high doses (1000 mg daily) of oral medroxyprogesterone acetate (HD-MPA). Of the 210 evaluable patients, the response rates were 26% [95% confidence interval (CI) 18-34%] for Awkly and 38% (95% CI 29-47%) for Awkly + HD-MPA (P = 0.08). There was no significant difference with regard to duration of response. Median survival was 11 months in both groups. Considerable toxicity was seen from HD-MPA, particularly weight gain and fluid retention. The present study provides evidence that, in concordance with preclinical studies and a previous randomised study, interaction between chemotherapy and HD-MPA may exist in breast cancer normally resistant to hormone therapy. For further studies, other gestagens and/or a dose reduction could be investigated.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Minority influence: a meta-analytic review of social influence processes.

A meta-analytic review of 97 minority influence experiments evaluated the processes by which sources advocating deviant, minority opinions exert influence. Minority impact was most marked on measures of influence that were private from the source and indirectly related to the content of the appeal and less evident on direct private influence measures and on public measures. This attenuated impact of minorities on direct private and public measures suggests that in response to normative pressures, recipients avoided aligning themselves with a deviant source. Mediator analyses revealed that minorities perceived as especially consistent in the advocacy of their views were especially influential. The relation between normative and informational pressures in the minority influence paradigm was discussed.

Humans↗
PubMed1994

Nurses' experiences of change: a new professional collaboration model and all-R.N. staffing.

Changes in staffing toward a higher number of R.N.'s are common in a number of countries today. This article aims at describing the experiences of a management-induced change from mixed to all-R.N. staffing. All R.N.s in a surgical ward at a Swedish university hospital were interviewed two months after such replacements were completed. The nurses described a period of chaos and conflicts but also of support for the idea and enthusiasm for the future. A more careful planning of the change process is to be recommended.

Hospitals, University↗
PubMed1993

Maxillary sinus augmentation: histomorphometric analysis of graft materials for maxillary sinus floor augmentation.

This study used histomorphometric analysis to quantitate the bone composition of four different sinus grafting materials biopsied at the time of implant installation. The study consisted of five patients in whom eight bone biopsies were obtained from seven grafted sites. The grafting materials consisted of hydroxylapatite (HA) granules mixed with cortical chin bone, HA mixed with demineralized bone powder, HA alone, and cortical chin bone alone. Histomorphometry was performed using backscattered scanning electron microscopy images and a computerized image analysis system. The biopsy cores yielded 46 sections from which a total of 255 fields, measuring 2.0 mm x 2.0 mm each, were imaged and analyzed. The biopsy cores contained 44.4% bone after grafting with HA granules and chin bone, 59.4% bone after grafting with chin bone alone, 20.3% bone after grafting with HA granules alone, and 4.6% bone after grafting with HA granules and demineralized bone powder. The small number of biopsies did not permit analysis of statistical significance. However, this study demonstrated the feasibility of correlating mineralized tissue composition of different sinus grafting materials with clinical outcome after dental implant installation.

Aged↗
PubMed1993

Surgical considerations for endosseous implants in the craniofacial region: a 3-year report.

From 1987 to 1990, 28 patients were treated with titanium implants (Brånemark flange fixtures) in the craniofacial area for the support of craniofacial prosthesis or anchorage of bone-conduction hearing aids in the Orofacial Implant Center at the University of California, Los Angeles (UCLA). A total of 88 implants were placed, of which 22 were placed in previously irradiated areas. Twenty-three of the implants were placed in the orbital area, 37 in the mastoid area, 20 in the nasal area, and eight in various other craniofacial regions. Seven implants were lost in four different patients. The proper location and positioning of implants in specific areas of the craniofacial regions, as well as soft-tissue complications and management, are discussed.

Adolescent↗
PubMed1992

Psychological factors in orthognathic surgery.

27 patients subjected to various orthognathic surgery procedures were studied preoperatively and during a period of 18 months postoperatively by a team of psychologists to evaluate the patients' own opinions concerning the indication for surgery, information about the surgical procedure, the postoperative period and the long-term aesthetic and functional results. The patients were interviewed 5 times: 2 days before surgery, 2 days after surgery and 2, 6 and 18 months after surgery. The decision to undergo surgery was taken after a long period of time, 4 years on average, and half of the patients were influenced by their family or dentist before they made their decision. 60% gave three or more reasons for surgery, 85% mentioned functional problems, 74% facial appearance and 59% craniomandibular symptoms. 63% indicated that the facial appearance problems had negatively influenced their personal life and 44% their social life. Women experienced this problem more often than men. The results showed that the overall majority of patients were relieved of their presurgical problems. The aesthetic improvement was better than expected. It was found that improvements in facial features had a beneficial influence on the patients as individuals and also on their social life situation.

Adolescent↗
PubMed1992

Sensitivity to a low calcium diet in different bones: an experimental study in the adult rat.

Adult male Sprague-Dawley rats weighing an average of 550 g were age matched into one control group and one group given a low calcium diet. The animals were followed for 34 wk. There was a similar loss of cancellous bone tissue in the proximal tibia, the first tail vertebra and the mandible due to calcium deficiency. The bone loss was not related to the initial amount of cancellous bone or to the bone-forming activity, which did not differ between experimental and control animals.

Animals↗
PubMed1992

Short term bone healing in calcium deficiency osteopenia and disuse osteopenia: experimental studies in adult rats.

Adult male Sprague-Dawley rats (average weight 530-540 g) were studied in two different series. In series I, studying disuse osteopenia, the experimental rats had all maxillary molars extracted on one side. After 16 wk they had their mandibular first molar of the corresponding side extracted and were followed for another 4 wk. In series II, studying calcium deficiency osteopenia, the experimental rats were given a low calcium diet for 16 wk and at this time had their mandibular first molars extracted. Both disuse and calcium deficiency caused osteopenia, which did not seem to impair the healing process after tooth extraction in the short term. One puzzling finding in the disuse series (I) was that the alveolar height at the extraction site was higher in the experimental than in the control group 4 wk after extraction.

Alveolar Process↗
PubMed1992

Clinical pharmacokinetics of endocrine agents used in advanced breast cancer.

Endocrine therapy is important in the treatment of advanced breast cancer. The prototype antiestrogen tamoxifen and the prototype aromatase inhibitor aminoglutethimide have been in clinical use for more than 2 decades, as have synthetic progestin derivatives. Currently, several novel antiestrogens and aromatase inhibitors are used to treat breast cancer. This paper reviews the present knowledge of the clinical pharmacokinetics of these drugs. Drug monitoring in plasma and other body fluids has been improved over recent years by the introduction of sensitive and specific high performance liquid chromatography and gas chromatography-mass spectrometry methods. However, we still lack information on such basic pharmacokinetic parameters as the bioavailability of several of these drugs. It is important to study not only plasma but also tissue drug concentrations.

Aromatase Inhibitors↗
PubMed1992

Progestins in breast cancer treatment. A review.

The two most widely used synthetic progestins in breast cancer treatment, medroxyprogesterone acetate (MPA) and megestrol acetate (MA), are reviewed with regard to pharmacological, endocrinological and clinical aspects. In high oral doses as second- or first-line endocrine therapy in advanced breast cancer, they give a similar response rate as tamoxifen (TAM) and aminoglutethimide (AG). The mechanism of action is probably complex. Considerable changes in serum levels of different hormones are induced by progestin treatment. The decrease of serum estrone sulfate (E1S) may be part of the therapeutic mechanism. Some studies suggest that the two drugs, MPA and MA, have a different mode of action, and possibly a low cross resistance. Randomized studies using the two progestins with a cross-over design may answer these questions. Further studies on the influence of progestin on different receptors and growth factors are warranted. To determine the most effective clinical dose of the two progestins, studies with increasing therapeutic doses are needed.

Breast Neoplasms↗
PubMed1990

500-Kilodalton calcium sensor regulating cytoplasmic Ca2+ in cytotrophoblast cells of human placenta.

Two monoclonal IgG antibodies E11 and G11, which react with parathyroid and kidney tubule cells, are in the present communication demonstrated to immunostain the surface of cytotrophoblast cells in human placenta. The G11 but not the E11 antibody has earlier been found to interfere with the sensing and gating of extracellular calcium in parathyroid cells. Microfluorometric measurement of the cytoplasmic calcium (Ca2+i) concentration was performed on suspended placental cells loaded with fura-2. The E11-positive placental cells displayed biphasic and parathyroid-like increases in Ca2+i in response to extracellular Ca2+. This increase was blocked by the G11 antibody and absent in the E11-negative placental cells. A sandwich enzyme-linked immunosorbent assay was constructed in which the G11 and E11 antibodies were shown to react with the same molecule. This calcium sensor was isolated and found to consist of a single, glycosylated polypeptide of approximately 500 kDa.

Antibodies, Monoclonal↗
PubMed1990

Influence of aminoglutethimide on the metabolism of medroxyprogesterone acetate and megestrol acetate in postmenopausal patients with advanced breast cancer.

In this study the influence of amino-glutethimide (AG) on the disposition of medroxyprogesterone acetate (MPA) and megestrol acetate (MA) was studied. When 1,000 mg AG daily was supplementally given to six patients on chronic treatment with MPA (1,000 mg/day) or MA (160 mg/day), mean serum levels of progestin were reduced by 74% as compared with control levels (P less than 0.03). AG did not change the blood clearance rate of MPA when the latter was given i.v. This discrepancy between AG's influence on oral and parenteral progestin disposition could be explained by pharmacokinetic properties of the progestins, and our results suggest that AG stimulates the metabolism of progestins. The decrease in MPA and MA serum levels was accompanied by an increase in serum cortisol, sex hormone-binding globulin (SHBG) and testosterone levels. This suggests that AG reduces the biological activity of progestins.

Administration, Oral↗
PubMed1990

Cyclical use of tamoxifen and high-dose medroxyprogesterone acetate in advanced estrogen receptor positive breast cancer.

One-hundred and seventy patients with estrogen receptor positive (greater than or equal to 10 pmol/g protein) advanced breast cancer have been treated in a prospective randomized study either with continuous tamoxifen 30 mg x 1 daily (TAM), or with TAM 30 mg x 1 daily for 8 weeks alternating with medroxyprogesterone acetate 500 mg x 2 daily for 8 weeks (TAM/HD-MPA). The response rate was 62% in the group treated with cyclic TAM/HD-MPA versus 41% in the TAM alone group (p = 0.02). There was no significant difference in duration of remissions or survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Influence of progestins on serum hormone levels in postmenopausal women with advanced breast cancer--I. General findings.

The influence of oral high dose progestin (medroxyprogesterone acetate, MPA and megestrol acetate, MA) treatment on serum hormone levels was studied in ten postmenopausal women with advanced breast cancer. The gonadotropins and ACTH were significantly reduced by greater than 50 and 23%, respectively. Serum cortisol, DHEAS, androstenedione and testosterone were all significantly reduced (mean reduction between 64 and 76%), while serum estrone, estradiol and estrone sulfate were significantly reduced by 20-30%. Sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CGB) were reduced by 68 and 25%, respectively. Although the dose of MA used (160 mg/day) was only 1/6 of the MPA dose (1000 mg/day), the mean serum level of MA was 2-fold higher than the mean serum level of MPA. MPA treatment gave a more pronounced suppression of SHBG than MA treatment, while estrone sulfate levels were more suppressed by MA. These findings suggest a differential effect of MPA and MA on certain plasma hormones, possibly of importance for understanding the mechanism of action of the two drugs. The reduction of estrone sulfate may be beneficial for the action of MA against breast cancer.

Aged↗
PubMed1990

Influence of progestins on serum hormone levels in postmenopausal women with advanced breast cancer--II. A differential effect of megestrol acetate and medroxyprogesterone acetate on serum estrone sulfate and sex hormone binding globulin.

Serum estradiol, estrone, estrone sulfate and sex hormone binding globulin were measured in 10 postmenopausal patients with advanced breast cancer receiving sequential treatment with medroxyprogesterone acetate and megestrol acetate. Treatment with megestrol acetate caused a non-significant reduction in serum estradiol (mean reduction of 19%, 0.05 less than P less than 0.1) but significant reductions in serum estrone (mean reduction of 20%, P less than 0.02) and serum estrone sulfate (mean reduction of 54%, P less than 0.005) compared to treatment with medroxyprogesterone acetate. In contrast, treatment with medroxyprogesterone acetate reduced serum sex hormone binding globulin more compared to treatment with megestrol acetate (mean reduction of 69%, P less than 0.01). These findings suggest that the two progestins have differential effects on serum hormone levels. The finding that treatment with megestrol acetate causes a significant reduction in serum estrone sulfate level warrants further investigations of this potentially important mechanism of action of this drug in advanced breast cancer.

Aged↗
PubMed1990

The actual dose delivery from a diazepam enema differs depending on the patients position during administration.

In a randomized single-blind cross-over study on 14 volunteers the relation between dose, effect and serum concentration was studied when diazepam in solution was administered in a dose of 0.5 mg/kg bodyweight rectally with the volunteer placed either laterally or prone. When lying prone the delivered diazepam dose was on average 24% higher compared to in the lateral position. The difference in delivered dose affected sedation as well as serum concentration but did not prolong recovery time. At the time of clinical recovery, the serum concentration was still at a very high level. Oxygen (p02) and carbon dioxide (pCO2) tensions were monitored transcutaneously in 9 subjects and were unaffected by the sedative level. The study suggests that when diazepam enemas similar to the ones used here, they should be administered with the patient in a prone position.

Administration, Rectal↗