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P Gröhn

Publications and source records attributed to P Gröhn.

At least 19 recordsLinked to original sources
PubMed2000

Non-invasive evaluation of the location, the functional integrity and the oxygen supply of implants: 19F nuclear magnetic resonance imaging of perfluorocarbon-loaded Ba2+-alginate beads.

19F nuclear magnetic resonance imaging (MRI) can be used as a non-invasive tool to simultaneously determine the location, the integrity and the oxygen supply of Ba2+-alginate implants. This requires that the beads (implants) are pre-loaded with the perfluorocarbon compound F-44E. Implantation of solid 19F-labelled beads into the peritoneum, below the kidney capsule or into the muscle of Wistar WU rats demonstrated that these beads could be detected by 19F-MRI for up to 18 months after implantation. This indicated that F-44E is not considerably released from the beads during implantation. The signal to noise ratio of liquid-core beads was higher by a factor of 4 than the signal to noise ratio of solid beads, but liquid-core beads were more fragile and also too large for implantation under the kidney capsule and into the intramuscular tissue. Quantitative 2-dimensional 19F-T1 maps (resolution 0.5 x 0.5 mm) could be deduced from 19F-MRI measurements. These T1-maps correlated to the local pO2-values. The partial oxygen pressure estimated in F-44E-loaded Ba2+-alginate beads showed that the oxygen supply inside the beads was very poor when they were implanted below the kidney capsule or into the peritoneal cavity. These low pO2-values obtained for the renal subcapsular site and the peritoneum may explain the failure of previous immunoisolated islet transplantation studies using these locations.

Alginates↗
PubMed1999

19F-MRI in vivo determination of the partial oxygen pressure in perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity and different tissues.

Semipermeable hydrogels formed with a biocompatible alginate solution and Ba(2+) ions protect encapsulated cells and tissues from a foreign immune system. For the viability and metabolic activity of the encapsulated materials, a sufficient oxygen supply inside the capsules is necessary. Quantitative (19)F-MRI was performed on perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity, the musculus quadriceps femoris, and beneath the kidney capsule of rats, in order to determine in vivo the partial oxygen pressure (pO(2)) inside the capsules at these implantation sites. The temporal behavior of the pO(2) values was observed for at least 3 months. The most stable values over time were observed in the kidney, where inter-rat pO(2) differences were considerable. In the muscle, the values were very high directly after implantation and decreased to nearly zero after 2 weeks. In the peritoneal cavity, values changed randomly over a wide range between different rats and over time. Magn Reson Med 42:1039-1047, 1999.

Alginates↗
PubMed1997

Biocompatibility of mannuronic acid-rich alginates.

Highly purified algin preparations free of adverse contaminants with endotoxins and other mitogens recently became available by a new purification process (Klöck et al., Appl. Microbiol. Biotechnol., 1994, 40, 638-643). An advantage of this purification protocol is that it can be applied to alginates with various ratios of mannuronic acid to guluronic acid. High mannuronic acid alginate capsules are of particular practical interest for cell transplantation and for biohybrid organs, because mannuronate-rich alginates are usually less viscous, allowing one to make gels with a higher alginate content. This will increase their stability and reduce the diffusion permeability and could therefore protect immobilized cells more efficiently against the host immune system. Here we report the biocompatibility of purified, mannuronic acid-rich alginate (68% mannuronate residues) in a series of in vitro, as well as in vivo, assays. In contrast to raw alginate extracts, the purified product showed no mitogenic activity towards murine lymphocytes in vitro. Its endotoxin content was reduced to the level of the solvent. Animal studies with these new, purified algin formulations revealed the absence of a mitogen-induced foreign body reaction, even when the purified material (after cross-linking with Ba2+ ions) is implanted into animal models with elevated macrophage activity (diabetes-prone BB/OK rat). Thus, alginate capsules with high mannuronic acid content become available for applications such as implantation. In addition to the utilization as implantable cell reactors in therapy and biotechnology, these purified algins have broad application potential as ocular fillings, tissue replacements, microencapsulated growth factors and/or interleukins or slow-release dosage forms of antibodies, surface coatings of sensors and other invasive medical devices, and in encapsulation of genetically engineered cells for gene therapy.

Alginates↗
PubMed1997

Collagen-coated Ba(2+)-alginate microcarriers for the culture of anchorage-dependent mammalian cells.

Several types of microcarriers suitable for large-scale cultivation of mammalian cells are commercially available. However, many of these carriers have disadvantages, e.g., the need for enzymatic digestion for cell harvesting, size limitations and insufficient biocompatibility. These limitations have been overcome by the development of collagen-coated Ba(2+)-alginate microcarriers. Ba(2+)-alginate microspheres, made with the air-jet droplet generator technique, were collagen-coated by incubation in a 0.5% collagen solution, with subsequent gelling of the collagen layer around the alginate microspheres. Human chang liver (CCL-13) and mouse fibroblast (L929) cell lines were cultivated in stationary, unstirred cultures as model systems. After a lag phase of nearly 24 h, the cells grew rapidly on these microcarriers and reached confluence after 3 days. The microcarrier cultures were stable for an additional 4-9 days and longer. Cells were harvested either by trypsinization or by dissolution of the alginate matrix using 5 mM EDTA. The main advantages of this new microcarrier system are that the preparation procedure is easy and can be accomplished on demand with standard laboratory equipment.

Alginates↗
PubMed1997

[Day case surgery nursing development].

Day case surgery in the North Karelia Central Hospital has been centred to LYHKI-unit which was opened in the autumn of 1994. The work and development is guided by a perioperative nursing model in which the patient's experiences and functions of nursing take place in three successive preoperative, intraoperative and postoperative phases. The more extensively the nurse participates in the pre and postoperative phases, the more skilled she is. The objective of development is a planned preadmission assessment between the patient and the nurse before the operation day. It is already realized for several patients, and documentation is improved by bringing into use a new case history form which is created according to the new perioperative nursing model. The nurses have committed themselves to implementation of the perioperative nursing. Developmental and educational activity is good in the unit. Plentiful positive feedback from the patients, encouraging support from the administration and continuous cooperation in developmental work have had an effect on the nurses' improved motivation for work. In the future the resources will be especially focused to the quality of care and to meet the societal challenges for day surgery.

Ambulatory Surgical Procedures↗
PubMed1995

Intermittent interferon and polychemotherapy in metastatic melanoma.

This study was conducted to evaluate the efficacy and the tolerability of a four-drug chemotherapy regimen combined with interferon alpha (IFN) in metastatic melanoma. Between March 1991 and August 1993, 55 patients with advanced melanoma were enrolled for the present multicentre phase II study. Forty-nine patients were eligible and evaluable for toxicity; 48 patients were evaluable for response. The treatment schedule consisted of a 5-day regimen of dacarbazine, vincristine, bleomycin and lomustine, plus 6 x 10(6) IU IFN alpha three times weekly subcutaneously for 2 weeks starting on day 8. The cycle was repeated on day 29. Among the 48 assessable patients, 16 objective responses were seen, yielding a response rate of 33% (95% confidence interval 20%-46%). Seven patients achieved a complete response (CR) of a median of 6+ months (range 1+ to 21+ months) and 9 patients achieved a partial response (PR) of a median of 9 months (range 4-13 months). The median overall survival was 12+ months (range 6+ to 23+ months) for the patients with CR and 15+ months (range 8-20 months) for the patients with PR. Even the survival of the 7 patients with stable disease was fairly long (median 12, range 7-17 months), appearing to be significantly longer than the survival of the 25 patients with progressive disease (median 5, range 1-24+ months). The treatment was moderately well tolerated, although all patients experienced some mild form of toxicity, mostly gastrointestinal symptoms, neurotoxicity and haematotoxicity. Grade 3-4 adverse effects were noted in 39% of the patients. No toxic deaths occurred. It can be concluded that the present regimen produces meaningful responses for patients with metastatic melanoma. A randomised study is needed to determine the effect on survival.

Adult↗
PubMed1995

The prognosis of stage III breast cancer treated with postoperative radiotherapy and adriamycin-based chemotherapy with and without tamoxifen. Eight year follow-up results of a randomized trial.

Sixty-one patients with primary node positive stage III breast cancers were randomized to receive postoperative radiotherapy and doxorubicin-based chemotherapy (eight cycles of CAFt: cyclophosphamide, adriamycin, oral ftorafur) with or without tamoxifen as adjuvant treatment. The five-year overall survival for all patients was 49% (with tamoxifen 48% and without tamoxifen 50%) and disease-free survival 33% (with tamoxifen 27% and without 39%). Local control for all patients was only 64% despite the postoperative radiotherapy. There was no significant difference between these two treatment groups in overall and disease-free survival or local control. The prognosis of stage III breast cancer remains grim despite modern adjuvant therapy. In addition to more effective systemic treatment more effective local therapy is also needed in order to obtain satisfactory local control. The most important studies in stage III breast cancer with 5-year survival results are reviewed here.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Large-scale production of Ba(2+)-alginate-coated islets of Langerhans for immunoisolation.

Islet xenografts immunisolated in alginate capsules have been proposed by many groups for clinical islet transplantation. However, diffusion limitations and the total volume of microcapsules required for transplantation are, among other things, factors which have so far prevented successful clinical application. In this study, these problems have been overcome by immobilisation of rat and porcine islets in a Ba(2+)-cross-linked alignate matrix using an air jet droplet generator technique in combination with subsequent density-gradient purification. This procedure leads to high yields of islets coated with a tailored, thin layer of cross-linked alginate which protects the islets against cytotoxic compounds present in human plasma. The recovery of encapsulated rat and porcine islets was about 70%. Empty capsules were nearly completely removed. Using this technique, the total volume of the resulting microcapsules increased only by a factor of about 1.5 compared to the volume of free islets. The technique can be used for large-scale production of coated islets.

Alginates↗
PubMed1994

Skin protection by sucralfate cream during electron beam therapy.

Acute skin reactions, such as erythema and moist desquamation, constitute major problems during radiotherapy of superficially located tumours. There are no drugs available for the skin care. Sucralfate, a widely used anti-ulcer drug, has anti-inflammatory properties, and it activates cell proliferation. Based on these data and our previous experience of sucralfate cream on the aging skin we performed a double-blind randomized study to compare the efficacy of sucralfate cream to a base cream in 50 breast cancer patients receiving postoperative electron beam therapy to their chest wall. The acute radiation reaction of the skin was statistically significantly prevented by the sucralfate cream. The recovery of the skin was also significantly faster in the sucralfate cream group. Side-effects due to the cream were rare.

Adult↗
PubMed1994

Combined intraperitoneal interferon alpha-2b and mitoxantrone in refractory ovarian cancer.

In a non-randomized clinical trial, combined intraperitoneal therapy with recombinant interferon alpha-2b (20-50 MU) and mitoxantrone (20-50 mg) was studied for recurrent ovarian cancer with ascites. Altogether 19 patients were treated. After primary operation, all patients had received intravenous chemotherapy, 16 of which included cisplatin. One patient had complete response, seven patients partial response, four no change and seven progressive disease. The mean duration of the responses was 5+ months (range 1-12), and mean survival time 4.5+ months (range 1-14+). Eight patients had side effects (flu-like symptoms, dyspnea, abdominal pain, vomiting, diarrhea, fever and bowel obstruction). It was concluded that the formation of ascites in refractory ovarian cancer can be reduced with intraperitoneal administration of interferon alpha-2b and mitoxantrone, with tolerable side effects.

Adult↗
PubMed1992

Treatment of metastatic carcinoid tumour with recombinant interferon alfa.

14 patients with metastatic carcinoid tumour were treated with recombinant interferon alfa 6-30 x 10(6) IU weekly for 3-25 (median 6.5) months. A decrease in the 24-h urinary 5-hydroxyindoleacetic acid (5-HIAA) level to less than 50% of the pretreatment value was observed in 5 of the 10 cases with an elevated urinary 5-HIAA level. In 4 of the 5 remaining patients, the 5-HIAA level decreased 30-50% from the pretreatment value. 5 of the 9 evaluable patients with carcinoid syndrome experienced symptomatic relief, but none became symptom-free. Severe toxicity was not observed. The median time to progression was 4.5 months, and, in patients with a greater than 50% decrease in 24-h urinary-5-HIAA, it was 17 months. Objective regression in tumour size could not be demonstrated in any of the patients.

Adult↗
PubMed1992

A phase II study of metastatic melanoma treated with a combination of interferon alfa 2b, dacarbazine and nimustine.

52 patients with metastatic melanoma have been treated with a combination of recombinant interferon-alfa-2b, dacarbazine and nimustine. The objective response rate was 23% with 9 complete responses (CR) and 3 partial responses (PR). The mean duration of the response was 18+ months for CR (6-31+ months) and 7 months for PR patients (4-10 months). The mean survivals were 24+ months (8-38 months) and 7 months (4-12 months), respectively. The mean duration of the response for patients with stable disease was 10+ months (2-48+ months) and the mean survival 17+ months (3-48+ months), while the patients with progressive disease died within 12 months (mean 4 months). The best responding sites were the lymph node, the lung and the subcutaneous metastases. Myelosuppression was the main adverse effect of the therapy. WHO grade 3-4 toxicity was seen in 27 patients leading to delay and reduced dosage of therapy; in 4 patients treatment was discontinued, 8 patients had no side effects. Combination therapy with interferon and dacarbazine and nimustine for metastatic melanoma offers no advantage over interferon and dacarbazine.

Adult↗
PubMed1992

The combination of radiotherapy, adjuvant chemotherapy (cyclophosphamide-doxorubicin-ftorafur) and tamoxifen in stage II breast cancer. Long-term follow-up results of a randomised trial.

Two hundred patients with node positive stage II breast cancer were randomised to four groups after radical mastectomy and axillary evacuation: (1) Postoperative radiotherapy, (2) Adjuvant chemotherapy with eight courses of CAFt (cyclophosphamide 500 mg m-2 + doxorubicin 40 mg/m-2 + ftorafur 20 mg kg-1 orally day 1-14) every fourth week, (3) Postoperative radiotherapy and adjuvant chemotherapy and (4) postoperative radiation, adjuvant chemotherapy and tamoxifen 40 mg daily for 2 years. Thirty-two per cent of the patients discontinued treatment due to GI-toxicity, while 26% required dose reductions due to leukopenia. Radiation pneumonitis was more frequent after the combination of postoperative radiotherapy with chemotherapy. There was a better relapse-free survival in the groups receiving chemotherapy compared to radiotherapy alone (P = 0.05), which was highly significant in a multivariate Cox analysis (P = 0.004). No significant survival differences were seen. Tamoxifen had no clear overall effect but there were better relapse-free (P = 0.04) and overall (P = 0.004) survival with tamoxifen in estrogen receptor positive patients, while estrogen receptor negative patients had a somewhat poorer survival (P = 0.07) after tamoxifen. Local control was better (NS) after the combination (93%) radiotherapy and chemotherapy compared to either treatment alone (76% with radiotherapy and 74% with chemotherapy at 5 years).

Administration, Oral↗
PubMed1990

Oral carmofur in advanced gastrointestinal cancer.

One hundred and twenty-four patients with a diagnosis of metastatic gastrointestinal cancer and no prior therapy were included in this clinical study of carmofur monotherapy, 300-500 mg/m2 daily for 6 weeks. For the 115 evaluable patients, the response rates were 19.4% in gastric cancer, 27.2% in cancer of mobile colon, and 12.5% in rectal cancer. No objective responses were seen in 38 patients with pancreatic cancer, although the disease of 13 of these patients has remained stable over a considerably long period of follow-up. The toxicity profile was interesting; the main adverse effects were urinary bladder symptoms and flush. Hematologic toxicity was minimal. The treatment proved to be safe and could be used for outpatients.

Administration, Oral↗