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Biomedical subjects

K Mahlberg

Publications and source records attributed to K Mahlberg.

At least 19 recordsLinked to original sources
PubMed1997

Prevention of high risk corneal graft rejection using cyclosporine A (CsA) incorporated into a collagen matrix.

The aim of this work was to compare the efficacy of cyclosporine (CsA) collagen shields and fragments in suppressing experimental allograft rejection in an animal model for high risk keratoplasty. Altogether 23 experimental animals were treated either with plain collagen shields, oral cyclosporine, collagen CsA shields, or with CsA collagen fragments after corneal transplantation (PKP) in previously vascularized corneas. The study medications were started immediately following PKP. For these animals slit lamp examinations were performed twice a week for the duration of the experiment and the signs of corneal rejection were observed. The animals were followed until an irreversible rejection or until the end of the experiment (14-149 days). The inflammation of the graft was also evaluated histologically when animals were sacrificed. The grafts treated with plain collagen shields all were rejected within 36 days, and the mean graft survival time for these corneas was 25 days. Five transplants that were treated with oral CsA had better survival, and two of five grafts stayed clear until postoperative day 119, when the treatment was stopped. The best graft survival was seen in grafts treated with CsA collagen fragments and all these stayed clear up to 77 days postoperatively. The treatment of the grafts with CsA collagen shields was almost as effective as with CsA fragments, and first signs of rejection appeared as late as nine weeks postoperatively in two of seven grafts. The other of these rejected corneas were later treated with CsA collagen fragments and showed a dramatic improvement in transparency of the cornea and disappearance of inflammation of the graft. The discontinuation of study medication caused an irreversible rejection to appear in a previously clear graft that had been treated successfully with any study medication. We conclude that topical CsA in shields or in fragments will provide a significant advance over systemic CsA alone, and that CsA fragments appear to be as effective as shields in preventing corneal allograft rejection.

Animals↗
PubMed1996

The effect of topical cyclosporin on conjunctiva-associated lymphoid tissue (CALT).

Topical cyclosporin A is increasingly being used in the treatment of ocular surface immune-mediated disorders. The availability of the drug in oil-based vehicles or collagen shields has restricted its use because of ocular irritation or blurring of vision. Although topical cyclosporin is being used more frequently, its effect on the immunocompetent cells of the conjunctiva is not known. Our aim was to study the effect of cyclosporin instillation on the immunocomponent cells of conjunctiva-associated lymphoid tissue (CALT) of Lewis rat, using a novel method of topical drug delivery. A suspension of collagen bits impregnated with cyclosporin A was instilled into eyes of Lewis rats for 4 days (group 1) or 8 days (group 2). Control rats (group 3) received the suspension without cyclosporin. Frozen sections of eyelids and conjunctiva were immunostained with the following monoclonal antibody markers: W3/13 (CD3), W3/25 (CD4, macrophages), OX-8 (CD8), MARD-3 (B cells), ED1, ED2 (macro/monocytes), OX-6 (class II MHC, Ia) and OX-39 (CD25, IL-2 receptor). Intraepithelial (IE) and substantia propria cells for each subset were counted and expressed as numbers per section. By day 8, intraepithelial and substantia propria cells for all the above markers, except B cells, showed a significant reduction in numbers. The p values were < 0.02 for W3/13 (CD3), W3/25 (CD4), OX-8 (CD8), OX-39 (CD25) (IE only), ED1, ED2 and OX-6 positive cells. Goblet cells of control animals showed strong positive reaction with OX-39 (CD25) antibody. This was completely abolished following 8 days of topical cyclosporin. This study demonstrated that topical cyclosporin A induces a marked reduction in numbers of all subtypes of immunocompetent cells in the conjunctival epithelium and substantia propria.

Administration, Topical↗
PubMed1994

Use of collagen shields in cataract surgery.

A randomized, prospective, multicenter study evaluated the efficacy and safety of using collagen shields to deliver drugs after cataract surgery. Collagen shields saturated with an antibiotic and a steroid were placed in 90 eyes postoperatively. A control group of 93 eyes received the same drugs through a peribulbar/retrobulbar injection. One day after surgery, the shield group had significantly less corneal edema, conjunctival hemorrhaging, and postoperative pain and fewer corneal opacities. All symptoms except the conjunctival hemorrhaging disappeared by day seven. Our study suggests that using collagen shields for drug delivery after cataract surgery decreases tissue damage and increases patient comfort without adverse side effects.

Adult↗
PubMed1991

Anterior uveitis in children. An analysis of 75 cases with special reference to retinal anti-S antibodies.

In this prospective study of childhood uveitis, 75 children with anterior uveitis were analyzed to determine whether a relationship could be found between the occurrence of uveitis, its clinical features, and humoral immunity to retinal S-antigen. For the purposes of analysis, children were divided into acute (18 cases) and chronic (57 cases) categories, depending on the duration of ocular inflammation. Clinical features of both of these groups were compared and significant differences were found in the occurrence of unilateral vs bilateral involvement, the incidence of complications, and visual outcome. Serum samples from children with acute (7 cases) and chronic uveitis (28 cases) and from healthy children (132 cases) were tested for antibodies to S-antigen by enzyme-linked immunosorbent assay (ELISA). A statistically significant difference in the level of specific antibodies between patients with chronic uveitis and controls was found. However, there was no difference between children with acute uveitis and healthy patients, nor was there any correlation between the severity of uveitis and antibody titer. For further elucidation of the significance of circulating anti-S antibodies, 14 children with chronic anterior uveitis were followed for as long as 18 months after the initial visit. Multiple serum antibody titers to bovine retinal S-antigen were determined and compared with the clinical activity at the time of each sampling. In only 6 of 14 patients did the titers to S-antigen tend to decrease with clinical improvement and stabilize at titers somewhat higher than normal values.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Prevention of experimental corneal allograft rejection in rabbits using cyclosporin-collagen shields.

Topical administration of cyclosporin A, a highly hydrophobic cyclic undecapeptide, has been relatively ineffective in preventing corneal allograft rejections due to poor drug penetration. Therefore, we investigated a new continuous-delivery system for cyclosporin A using collagen bandage shields fabricated from porcine scleral tissue. Collagen bandage shields containing 4 mg cyclosporin A were used for the treatment of four corneal allografts embedded in prevascularized rabbit corneas. Four controls were treated with shields containing no cyclosporin A. The shields were changed every 2nd day and signs of rejection were recorded. All controls were rejected by the end of the experiment. Treatment with collagen shields containing cyclosporin A effectively prevented such rejection. The clinical examinations were also confirmed with histopathological analysis. The results indicate that collagen shields can slowly release cyclosporin A and increase the penetration time for the drug. Thus, they are excellent delivery systems for hydrophobic drugs with poor penetration properties.

Animals↗
PubMed1989

The effect of gabexate mesilate on the outcome of acute hemorrhagic pancreatitis in pigs.

The effects of gabexate mesilate (GM) on hemodynamics and phospholipase A2 activities (PLA2) during acute hemorrhagic pancreatitis (AHP) were studied in 17 piglets which were randomly divided into three groups: The control group (CG) received only the fluid replacement, whereas the pretreatment group (PG) was given an infusion of GM (20 mg/kg/5h), which was started 30 min before and in the treatment group (TG) 30 min after the induction of AHP. AHP was induced by infusing a mixture of trypsin and sodiumtaurocholate (1 ml/kg) into the pancreatic duct, and the animals were followed up for 5h. Two animals of the CG died, but no mortality was observed in the other groups. Histologically, acute hemorrhagic pancreatitis was detected in all animals, but no significant differences were observed between the groups. PLA2 activity in the serum increased rapidly after the induction of AHP in the CG, and it was significantly (P less than 0.05) higher 5h after the induction in the CG than in TG or PG. No significant differences developed between the groups in cardiac indices or hemodynamic pressure parameters during the 5h of surveillance, but the volume of secreted exudate into the peritoneal cavity was significantly (P less than 0.05) smaller in the PG than in the CG. In conclusion, GM treatment and pretreatment reduced mortality and the amount of the secreted ascitic fluid during AHP. Moreover, the activity of circulating PLA2 was inhibited in the groups receiving GM.

Acute Disease↗
PubMed1989

Purification of bovine and human retinal S-antigen using immunoabsorbent polymer particles.

Bovine retinal S-antigen was prepared using gel filtration chromatography followed by DEAE A-50 or QAE A-50 anion-exchange chromatography. The final purification was performed using immunoadsorbents made from polymerized polyvalent antiserum (rabbit) to bovine serum components. The purity of the antigen was confirmed by polyacrylamide gel electrophoresis, double diffusion according to Ouchterlony, immunoblotting and by producing monospecific antiserum to the retinal S-antigen. Both S-antigen preparations (DEAE and QAE) proved to be highly uveitogenic, causing experimental allergic uveitis in guinea pigs within 14 days of immunization. DEAE separated the antigen into three protein peaks but QAE only into one distinct protein peak. All these protein peaks were S-antigen-active and the yield was about the same using both separation systems. After optimizing the purification for bovine retinas, human retinal S-antigen was also prepared.

Animals↗
PubMed1987

Correlation between histopathological, clinical and biochemical parameters in S-antigen-induced experimental autoimmune uveitis in guinea-pigs.

Footpad immunization with purified bovine retinal S-antigen in complete Freund's adjuvant was used to induce experimental allergic uveitis in 32 guinea-pigs. Thirteen animals immunized only with complete Freund's adjuvant were used as controls. Ninety-three point seven per cent of the animals immunized with S antigen developed clinical experimental allergic uveitis while none of the controls had any clinical manifestation of uveitis. Histopathological analysis in the experimental group revealed mono- and polymorphonuclear cell infiltration in the choroid, ciliary body and iris. Simultaneous disruption of the outer segment of photoreceptor cell layer was also noticed. For the anterior segment of the eye there was a strong correlation between the histopathological grading and the clinical grading. For the posterior segment this correlation was, however, poor. Histopathological changes in the eye were correlated with the clinical grading and biochemical parameters (phospholipase A2, prostaglandin E2, leukotriene C4, proteins and myeloperoxidase) measured from aqueous humour, serum samples and ciliary body-iris homogenate. Protein and phospholipase A2 levels in the aqueous humour correlated well with the histological grading of the anterior segment of the eye. The myeloperoxidase activity, measured from ciliary body-iris homogenate, also correlated with the inflammatory cell infiltration in the anterior segment. Leukotriene C4 and prostaglandin E2 levels in aqueous humour did not correlate with the histopathological, or with the clinical grading, although elevated mean values were recorded in eyes having uveitis. Gamma glutamyl transpeptidase, measured in the serum, had a poor correlation with the histological grading for the anterior segment. All other parameters, measured in serum, did not correlate with the histopathological or the clinical grading. Histopathological changes in the anterior uvea are thus reflected by elevated protein and phospholipase A2 levels in aqueous humour as well as by myeloperoxidase activity in ciliary body-iris homogenate.

Animals↗
PubMed1987

Suppression of experimental autoimmune uveitis in guinea pigs by ethylenediamine tetra-acetic acid, corticosteroids, and cyclosporin.

In the present study, footpad immunization using purified bovine retinal S-antigen mixed with complete Freund's adjuvant was used to induce experimental autoimmune uveitis (EAU) in guinea-pigs. The EAU-control group, receiving no treatment, was compared with test animals which received topically and systemically administered ethylenediamine tetra-acetic acid (EDTA) or subcutaneous and topical corticosteroid treatment, as well as a test group which received cyclosporin A subcutaneously. The severity of the uveal inflammation was clinically evaluated by slit lamp examination. The phospholipase A2 (PLA2) activity and the protein content of the aqueous humour as well as the myeloperoxidase (MPO) activity in the ciliary body were also determined. Serum antibodies to retinal S-antigen were followed using an immunoassay technique. Topical or subcutaneous EDTA significantly reduced the ocular inflammatory response to S-antigen induced autoimmune uveitis in the guinea-pigs. The best clinical suppression of EAU was obtained in the group treated subcutaneously with EDTA. Steroid treatment also suppressed the inflammatory processes in the eyes but was not as effective as EDTA or cyclosporine A. PLA2 activity in the aqueous humour and the MPO levels measured from iris-ciliary body homogenate were significantly lower in the groups treated subcutaneously with EDTA or cyclosporin A as compared with the untreated EAU-controls. The guinea-pigs treated subcutaneously with EDTA and cyclosporin A showed the lowest antiserum titres to retinal S-antigen. The prevention of PLA2 activity in aqueous humour after EDTA treatment correlated well with the milder inflammatory response in the eye. Based on the present study, it is therefore suggested that EDTA both locally and systematically reduces the S-antigen induced inflammatory response by decreasing the formation of inflammatory mediators derived from the arachidonic acid cascade.

Adrenal Cortex Hormones↗
PubMed1987

Suppression of experimental autoimmune uveitis in guinea-pigs by inhibition of phospholipase A2.

Retinal S-antigen mixed with complete Freund's adjuvant was used to induce experimental autoimmune uveitis (EAU) in guinea-pigs. Guinea-pigs receiving no treatment, was compared with test animals which received topically and systemically administered KLM-583B, a phospholipase A2 (PLA2) inhibitor, or subcutaneous (sub. cut) and topical corticosteroid treatment, as well as a test group which received cyclosporin A suc. cut. The best clinical suppression of EAU was obtained in the group treated suc. cut with KLM-538B. Steroids also suppressed the inflammation in the eyes but was not as effective as KLM-583B or cyclosporine A. PLA 2 activity in the aqueous humour and the myeloperoxidase (MPO) levels measured from iris-ciliary body were significantly lower in the groups treated suc. cut. with KLM-583B or cyclosporin A. Guinea-pigs treated suc. cut. with KLM-583B and cyclosporin A had the lowest antiserum titres to retinal S-antigen.

Animals↗
PubMed1987

Phospholipase A2, leukotriene C4 and prostaglandin E2 levels in aqueous humour of guinea pigs with experimental S-antigen induced autoimmune uveitis.

Purified S-antigen was used to induce experimental autoimmune uveitis in 42 guinea pigs. 16 animals were used as controls. Footpad immunization with fresh bovine S-antigen in physiologic saline mixed with complete Freunds's adjuvant induced a clinical disease in 95% of the eyes in test animals. In aqueous humour the increase in phospholipase-A2 and proteins as well as myeloperoxidase measured from iris-ciliary blocks correlated well with the severity of uveitis evaluated by clinical grading. Leukotriene C4 and prostaglandin E2 were only elevated in aqueous humour drawn from eyes showing a mild form of uveitis. Neither leukotriene C4 nor prostaglandin E2 were detected in eyes graded as clinically moderate or severe. In serum samples phospholipase A2, leukotriene C4, prostaglandin E2 and gamma glutamyl transpeptidase were measured. Of these biochemical parameters, only gamma glutamyl transpeptidase was significantly elevated in test animals with experimental autoimmune uveitis. Histological analysis revealed focal mononuclear cell infiltrations in the choroid. Mononuclear as well as polymorphonuclear cell infiltration was seen predominantly in the pars plana region of the ciliary body of test animals with uveitis. Simultaneous destruction of the outer segments of the photoreceptor layer was seen.

Animals↗
PubMed1986

Postoperative active specific immunotherapy with supportive measures in patients suffering from recurrent metastasized melanoma: case reports of six patients.

The clinical results from postoperative active specific immunotherapy using autologous polymerized tumor material in six patients suffering from metastasized melanoma is reported. Correction of an alleged systemic deficiency leading to malignant cell transformation was attempted by administering certain essential trace elements, amino acids, vitamins, and a diet containing lipids, extracted from the mammalian central nervous system, after heating. Vaccinations against influenza were also given as a precaution against certain viral infections sometimes seen to precede melanoma recurrence. The clinical results with this postoperative adjuvant therapy are so encouraging that we suggest that sterile tumor tissue should be saved at operation and treated to produce insoluble particles as an option for postoperative treatment of patients suffering from metastasized melanoma. Prospective randomized studies are indicated.

Adult↗
PubMed1985

Active specific immunotherapy with supportive measures in the treatment of palliatively nephrectomized, renal adenocarcinoma patients. A thirteen-year follow-up study.

The results of a 13-year (1971-1984) follow-up of specific active immunotherapy using polymerized autologous tumor tissue with adjuvants and supportive measures, following palliative nephrectomy in 71 patients suffering from advanced renal adenocarcinoma, are presented. The control patient group comprised 56 patients who received the best possible conservative treatment available. The statistically calculated life expectancy in the immunotherapy group is 44.5 months (SE 5.7) and in the control group 19.0 months (SE 3.3). The difference is statistically highly significant (generalized Wilcoxon [Breslow], t = 14.9, p less than 0.0001). There were no serious side effects from the immunization. The supportive measures entailing the administration of factors involved in cell regulatory functions mediated by the central nervous system, amino acids, trace elements, hormones and vitamins has still to be optimized.

Adjuvants, Immunologic↗
PubMed1980

Phospholipase A2 inhibitors and their possible clinical use in the treatment of acute pancreatitis.

A laboratory method was established for measurement of phospholipase A2 activity in buffer and serum. A series of different phospholipase A2 inhibitors was tested. The most effective inhibitors were Ca2+ chelating compounds like EDTA, DTPA, EGTA, and phytic acid. The calcium salt of EDTA also has some inhibitory effect. Serum phospholipase A2 activity in normal healthy control patients was measured. The activity in 27 patients with acute pancreatitis was tested. The activity was abnormally high in five patients. This activity was in vitro inhibited by EDTA and partly by CaNa2EDTA. The clinical picture of these patients did not differ from that of phospholipase-A2-negative patients. Six patients with acute pancreatitis were treated by intravenous infusion of CaNA2EDTA. Two of them had haemorrhagic pancreatitis and two were suspected of having early haemorrhagic pancreatitis. During the CaNa2EDTA infusion serum amylase and phospholipase A2 activities decreased. All patients recovered. No harmful side effects were noticed.

Acute Disease↗
PubMedDate not supplied

Compatibility of corticosteroids and antibiotics in combination.

PURPOSE: To study the compatibility of combinations of antibiotics and steroids commonly used in anterior segment surgery. SETTING: Research Laboratory, Helsinki University, Finland. METHODS: Aggregate production in vitro and in vivo was studied for three injectable antibiotics (cefotaxime sodium, tobramycin sulfate, and gentamicin) and four corticosteroids (triamcinolone acetonide, methylprednisolone sodium succinate, methylprednisolone acetate, and dexamethasone sodium phosphate) using conventional and dark-field microscopy. Aggregate formation on collagen shields and subconjunctival aggregate formation of tobramycin sulfate in combination with methylprednisolone acetate or dexamethasone sodium phosphate was also studied. RESULTS: Dexamethasone sodium phosphate (4 mg/mL) did not form aggregates with any of the three antibiotics tested. Cefotaxime sodium did not cause aggregates when 24 mg/mL of dexamethasone sodium phosphate was used both in vitro and in vivo or in association with collagen shields. CONCLUSIONS: To avoid undesired side effects, such as epithelial sloughing and corneal edema after collagen shield application, antibiotics and steroids must be carefully selected.

Animals↗