Surgical correction of astigmatism after perforating keratoplasty]

Microsurgical control of astigmatism after perforating keratoplasty has widely remained an unsolved problem in spite of many sophisticated suggestions and inventions. The frequent irregularity in the recipient cornea and poor predictability with respect to wound healing are the major obstacles. If spectacles or contact lenses cannot provide useful vision, postoperative surgical correction is needed. Ablative or thermal laser techniques have not been sufficiently tried for such cases to be justified, and one may hesitate anyway to apply destructive methods in transplants. We therefore still use T-incisions and wedge resections, which are said to be rather imprecise. Only 3 out of more than 700 keratoplasties performed in our clinic from 1987 through July 1991 required such procedures. Two more cases were referred by surgeons outside the hospital. All five surgical corrections resulted in a good longterm effect with considerable improvement of vision. Thus, as long as alternative methods for surgical correction of postkeratoplasty astigmatism have not proved to be superior, we should continue to practice these "old" methods, which, indeed, are not bad if properly applied.     

The release profiles of intact and enzymatically digested hyaluronic acid from semisolid formulations using multi-layer membrane system.

A multi-layer membrane system was used to measure in vitro release of hydrophilic macromolecules such as hyaluronic acid (HA) from semisolid formulations. One enzymatically digested HA-derivative with molecular mass of 22 kDa (HA-D) and 1200 kDa intact HA (HA) were incorporated into three semisolid formulations: water-containing hydrophilic ointment (WHO), amphiphilic cream (AC) and water-containing wool wax alcohol ointment (WWO). Because of the high hydrophilic properties of HA-D and HA, the artificial model membranes consisted of collodion as the matrix and glycerol as the hydrophilic acceptor phase. The area under the concentration-time curve and the mean dissolution time were used as a quantitative parameter to characterise the rate and extent of release in vitro. This study showed that the HA-D and HA release as hydrophilic substances from WHO was higher than both from AC and WWO. It was observed that 83% of HA-D1 was released from WHO after 2 h; in contrast, only 10% was released from 2% HA from the same vehicle during the same time. In conclusion, the in vitro availability of enzymatically digested HA-D was higher for WHO than for the other formulations, AC and WWO. Similarly, the availability of HA-D was higher than that of HA from the same formulations.     

Circulating growth factor levels are associated with tumorigenesis in neurofibromatosis type 1.

PURPOSE: Neurofibromatosis type 1 (NF1) is characterized by systemic development of neurofibromas. Early clinical diagnosis can be ambiguous, and genetic diagnosis can be prohibitively difficult. Dysregulation of a number of growth factors has been suggested to be a mechanism of pathogenesis. This study was performed to assess the contribution of circulating growth factors for diffuse tumorigenesis and the diagnostic value of circulating growth factor identification in serum. EXPERIMENTAL DESIGN: The growth stimulation of neurofibroma-derived cells by serum from NF1 patients was tested, and serum growth factor levels in a cohort of NF1 patients (n = 39) between the ages of 7 and 70 years were analyzed. RESULTS: Concentrations of midkine (MK) and stem cell factor, but not epidermal growth factor, were substantially increased in serum of NF1 patients when compared with healthy controls. Within the NF1 group, MK levels increased dramatically at puberty from an average of 0.79 ng/mL in patients <18 years to 1.18 ng/mL in patients >18 years old. Stem cell factor and MK concentrations above a defined threshold in serum of NF1 patients are of diagnostic benefit for 96% of patients in the cohort tested. Furthermore, serum from NF1 patients enhanced proliferation of human neurofibroma-derived primary Schwann cells and endothelial cells substantially better than normal serum. CONCLUSIONS: Enhanced circulating growth factor levels contribute to diffuse tumorigenesis in NF1 and may provide the basis for molecular diagnosis.     

Longitudinal monthly body measurements from 1 to 12 months of age: a study by practitioners for practitioners

A longitudinal growth study with monthly measurements during the 1st year of life was conducted by nine paediatricians working in private practice in Zurich. Of 92 children, none was lost to the study and only 32 of 1104 planned visits were missed; the quality of the measurements was comparable to that of a specialised university clinic. Compared to the Zurich Longitudinal Growth Studies, children of this study were considerably heavier and taller. In 92% of the subjects, growth velocity was at least once outside the reference range (3rd–97th percentile). For weight increments, the corresponding proportion was 87%. Conclusions The data indicate that current standards for the 1st year of life for the Zurich area might no longer be appropriate and need to be updated. The currently used velocity percentiles based on 3-monthly measurements are not suitable to assess individual height and weight increments calculated from monthly measurements. Received: 9 June 1997 / Accepted in revised form: 21 November 1997     

Interaction of topiramate with glycine receptor channels

Glycine receptor channels are pentameric ligand-gated ion channels that respond to the application of inhibitory neurotransmitters by opening of a chloride-selective central pore. Topiramate (TPM) is a broad-spectrum antiepileptic drug used as add-on or monotherapy for focal seizures. In the present study the interaction of TPM with glycine receptor channels was studied on outside-out patches from HEK293 cells expressing alpha1beta glycine receptor channels. The patch clamp techniques combined with ultra fast solution exchange enabled us to investigate the kinetics of receptor channels in presence of TPM. Our study showed no agonistic or potentiating effect for TPM on glycine receptor channels. However, in presence of 1 mM glycine + 1 mM TPM, the desensitization got faster and the peak current amplitude decreased. After the end of glycine + TPM pulses, off-currents occurred, suggestive for a specific channel block mechanism.     

Acupuncture of specific points influences cortical auditory evoked potentials--a volunteer crossover study

Specificity of acupoints remains a crucial question in acupuncture research. The aim was to investigate whether acupuncture of specific points influences the Cortical Auditory Evoked Potentials (CAEP). Ten healthy volunteers were enrolled in this study according to inclusion criteria. One of 4 acupoints: TH3, GB43 (both claimed as specific for auditory system by Traditional Chinese Medicine) and non-specific points H7 and ST44, was stimulated during one session. Each volunteer received 4 sessions of acupuncture with an interval of 1 week between the sessions. The latencies and amplitudes of CAEP were registered before and after the acupuncture during each session. The mean peak latencies of P2 component decreased after stimulation of TH3 by 11 ms and GB43 by 14 ms whereas the peak latencies of N2 component increased after stimulation of TH3 by 9 ms and GB43 by 4 ms compared to baseline values (p<0.05). The stimulation of H7 and ST44 did not produce any changes. These findings confirm the specificity of acupuncture points TH3 and GB43 in relation to auditory system.