[Kidney function of patients with healthy kidneys during cyclosporin treatment]

Corneal surface reconstruction using adult mesenchymal stem cells in experimental limbal stem cell deficiency in rabbits

PURPOSE

To investigate the ability of mesenchymal stem cells (MSC) to transdifferentiate to corneal epithelial cells in experimental limbal stem cell deficiency in rabbits.

METHODS

Total limbal stem cell deficiency was produced in 21 right eyes of 21 New Zealand rabbits; 6 eyes served as controls (group 1, G1). After removal of the conjunctival overgrowth, five eyes received amniotic membrane transplantation (AMT; G2). In four eyes, autologous limbal stem cell transplantation from the healthy eye was performed with AMT (G3). In another six eyes, enriched autologous MSC were injected under the amniotic membrane (AM) (G4). Within 280 days, corneoscleral discs were analysed for goblet cells, cytokeratin (CK) 3/12, connexin 43, β(1) -integrin, CK 19, α-enolase, p63 and ATP-binding cassette transporter subtype G-2 (ABCG-2) distribution patterns.

RESULTS

Cultivated MSC were positive for CK 3/12 and α-enolase, but negative for ABCG-2, p63 and connexin 43. On rabbit corneas, CK 3/12 was expressed in all corneal regions in all groups, but with significantly different intensities. Among all other parameters, expression levels of ABCG-2, β(1) -integrin and connexin 43 were significantly different between the transplanted groups and the control group. After a mean follow-up time of 172 (47-280) days, goblet cells were rarely present in the central cornea (G1-4).

CONCLUSION

CK 3/12 is not highly specific for differentiated corneal epithelium. Further, goblet cells are not a reliable marker for conjunctivalization in rabbits. Expression of ABCG-2, β(1)-integrin and connexin 43 after mesenchymal stem cell transplantation may indicate their ability to maintain their stem cell character or to transdifferentiate to epithelial progenitor cells.

Systemic ciclosporin A in high-risk keratoplasties

BACKGROUND

It was the purpose of this study to compile the results of all high-risk keratoplasties (kp) performed in our hospital under systemic ciclosporin A (Ci A) cover from 1987 through 1994.

METHODS

One hundred and thirty-one keratoplasties were performed. Ci A was administered for an average period of 9.4 months. We aimed at trough levels of 100-150 ng/ml (monoclonal RIA/TDx). The 29 kp in group A were second or third repeat kp and/or the recipient cornea had severe deep vascularization in all quadrants and/or a transplant position at the limbus was inevitable (expected risk: only immune reactions). The 40 kp in group B were threatened by severe ocular surface disorders (without severe limbal stem cell insufficiency) and by immune reactions (atopic keratopathy, keratoconus with severe endogenous eczema or chronic blepharokeratoconjunctivitis). In the 45 kp of group C resurfacing problems from severe limbal stem cell insufficiency and immune reactions were anticipated (severe burns, pseudopemphigoid or Lyell syndrome). Group D comprised 17 kp with various diagnoses (e.g. kp in newborns, rheumatic and Acanthamoeba keratitis).

RESULTS

In group A 91% of the grafts were clear 2 years postoperatively, in group B 76%, in group C 38% and in group D 18%. In 32 of 41 failed grafts (78%), resurfacing problems were the only reason for or participated in final graft failure. Immune reactions and other causes of graft failure were of minor importance.

CONCLUSIONS

(1) Systemic Ci A cover can efficiently suppress immune reactions. (2) With the suppression of immune reactions, resurfacing disorders become the most important single cause for functional graft failure. (3) For eyes with a considerable loss of limbal stem cells, limbal stem cell transplantation should be combined with systemic Ci A cover in order to improve the long-term prognosis for penetrating keratoplasty.

Effects of dietary sodium on blood pressure in IDDM patients with nephropathy

The objectives of the study were to assess the effects of moderate sodium restriction on blood pressure in insulin-dependent diabetic (IDDM) patients with nephropathy and high normal or mildly hypertensive blood pressure (primary objective), and to document possible associated changes of exchangeable body sodium, body volumes, components of the renin-angiotensin-aldosterone system, atrial natriuretic peptide, and catecholamines (secondary objective). Sixteen patients with untreated systolic blood pressure > or = 140 < 160 mmHg and/or diastolic blood pressure > or = 85 < 100 mmHg were included in a double-blind, randomized, placebo-controlled trial. After a 4-week run-in period on their usual diet and a 2-week dietary training period to reduce sodium intake to about 90 mmol/day, eight patients received 100 mmol/day sodium supplement (group 2) and eight patients a matching placebo (group 1) for 4 weeks while continuing on the reduced-sodium diet. Patients were examined at weekly intervals. Main response variables were mean values of supine and sitting systolic and diastolic blood pressure as measured in the clinic and by the patients at home. The differences in blood pressure between the beginning and the end of the blinded 4-week study period were calculated and the differences in changes between the two patient groups were regarded as the main outcome parameters. During the blinded 4-week study period, average urinary sodium excretion was 92 +/- 33 (mean +/- SD) mmol/day in group 1 and 199 +/- 52 mmol/day in group 2 (p = 0.0002). The differences in blood pressure changes between the two patient groups were 3.9(-1.2 to 9) mmHg [mean (95% confidence intervals)] for systolic home blood pressure, 0.9(-3.7 to 5.5) mmHg for diastolic home blood pressure, 4.9(-3.3 to 13.1) mmHg for clinic systolic blood pressure and 5.3(1 to 9.7 mmHg, p = 0.02) for clinic diastolic blood pressure. Combining all patients, there were relevant associations between changes of urinary sodium excretion and blood volume (Spearman correlation coefficient r = 0.57), blood pressure and angiotensin II (diastolic: r = -0.7; systolic: r = -0.48), and exchangeable body sodium and renin activity (r = -0.5). In conclusion, in this study of IDDM patients with nephropathy and high normal or mildly hypertensive blood pressure, a difference in sodium intake of about 100 mmol/day for a period of 4 weeks led to a slight reduction of clinic diastolic blood pressure. Studies including larger numbers of patients with various stages of nephropathy and hypertension are needed to definitely clarify the effects of sodium restriction in IDDM.

Altered clearance of N-1 methylnicotinamide associated with the use of low doses of cyclosporine

To improve the monitoring of patients on low doses of cyclosporine there is a need for new tests of tubular function. N-1 methylnicotinamide (NMM) is an endogenous organic cation that is secreted by the proximal tubule and its clearance can be measured. In 27 patients with psoriasis, serial measurements of NMN clearance, plasma aldosterone, plasma chloride, bicarbonate, and magnesium were compared with changes in the radionuclide measurement of glomerular filtration rate and renal blood flow before, during, and after a 3-month course of low-dose cyclosporine (< 5 mg/kg/d). N-1 methylnicotinamide clearance decreased significantly with cyclosporine only (2.5 mg/kg/d, n = 10, P < 0.01). Recovery of NMN clearance lagged behind that of glomerular filtration rate and renal blood flow. Serum magnesium decreased significantly on cyclosporine (2.5 mg/kg, n = 10, P < 0.01; 5 mg/kg, n = 9, P < 0.0001). In the whole group, plasma potassium increased significantly (n = 27, P < 0.02) and plasma aldosterone was inappropriately low. Low doses of cyclosporine in psoriasis cause a reduced clearance of NMN, hypomagnesemia, and a variable hyperchloremic acidosis. Nifedipine may alter these biochemical variables without necessarily improving renal hemodynamics. The delayed recovery of NMN clearance in comparison with renal haemodynamic measurements following cyclosporine therapy suggests that this noninvasive test of tubular function may be a marker of persisting cyclosporine nephrotoxicity and that it should be evaluated further.