Photopharmacology of Protease Inhibitors: Current Status and Perspectives

Proteases are involved in many essential biological processes. Dysregulation of their activity underlies a wide variety of human diseases. Photopharmacology, as applied on various classes of proteins, has the potential to assist protease research by enabling spatiotemporal control of protease activity. Moreover, it may be used to decrease side-effects of protease-targeting drugs. In this review, we discuss the current status of the chemical design of photoactivatable proteases inhibitors and their biological application. Additionally, we give insight into future possibilities for further development of this field of research.

Influence of Identity Development on Weight Gain in Adolescent Anorexia Nervosa

BACKGROUND

Anorexia Nervosa (AN) typically begins during early adolescence, an important phase of personality development. A substantial proportion of adolescent AN patients shows impaired personality functioning, which might be a relevant but understudied aspect of illness severity. The developmental status of identity as key element of personality is suggested to influence inpatient treatment outcome in adolescents with AN.

METHODS

This study analyzed existing data of N = 60 adolescents with AN. Multilevel models assessed the influence of identity functioning, measured by the Assessment of Identity Development in Adolescence (AIDA) at admission, on weight gain [BMI (body mass index), BMI-SDS (BMI standard deviation score)] during 10 weeks of inpatient treatment. Moreover, the influence of other indicators of illness severity, i.e., eating disorders and comorbid psychopathologies, was explored.

RESULTS

As expected, higher AIDA scores negatively influenced the course of weight gain. A similar effect was observed for other psychopathology measures, especially body image distortion. In general, higher weight at admission was associated with less weight gain. Higher weight at admission was also predicted by higher other psychopathology measures, but not AIDA scores.

CONCLUSION

The course of weight gain during inpatient treatment was hampered in adolescent AN patients who have difficulties developing a stable identity. Unlike other aspects of psychopathology, this was independent of the initial weight. Thus, in addition to the level of underweight and other aspects of psychopathology, difficulties in identity development constitute a relevant aspect of illness severity in AN. This recommends consideration of identity development during treatment.

Improvement of cognitive functions in chronic schizophrenic patients by recombinant human erythropoietin

Schizophrenia is increasingly recognized as a neurodevelopmental disease with an additional degenerative component, comprising cognitive decline and loss of cortical gray matter. We hypothesized that a neuroprotective/neurotrophic add-on strategy, recombinant human erythropoietin (rhEPO) in addition to stable antipsychotic medication, may be able to improve cognitive function even in chronic schizophrenic patients. Therefore, we designed a double-blind, placebo-controlled, randomized, multicenter, proof-of-principle (phase II) study. This study had a total duration of 2 years and an individual duration of 12 weeks with an additional safety visit at 16 weeks. Chronic schizophrenic men (N=39) with defined cognitive deficit (>or=1 s.d. below normal in the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS)), stable medication and disease state, were treated for 3 months with a weekly short (15 min) intravenous infusion of 40,000 IU rhEPO (N=20) or placebo (N=19). Main outcome measure was schizophrenia-relevant cognitive function at week 12. The neuropsychological test set (RBANS subtests delayed memory, language-semantic fluency, attention and Wisconsin Card Sorting Test (WCST-64) - perseverative errors) was applied over 2 days at baseline, 2 weeks, 4 weeks and 12 weeks of study participation. Both placebo and rhEPO patients improved in all evaluated categories. Patients receiving rhEPO showed a significant improvement over placebo patients in schizophrenia-related cognitive performance (RBANS subtests, WCST-64), but no effects on psychopathology or social functioning. Also, a significant decline in serum levels of S100B, a glial damage marker, occurred upon rhEPO. The fact that rhEPO is the first compound to exert a selective and lasting beneficial effect on cognition should encourage new treatment strategies for schizophrenia.

Fear of dental treatment and its possible effects on oral health

Working with 59 ambulant patients (average age 42 +/- 16 years), male and female, at the Dental Clinic of the University of Mainz, questions concerning fear of treatment were raised, and the answers compared with clinical findings on the status of oral health and with habits of oral hygiene. Pulse and blood pressure were also measured before and after treatment. 65% of the patients reported some level of fear of dental treatment. Younger patients had significantly more fear of treatment than older patients (p <0.05, Fisher-test). Patients reported the noise and vibration of the drill (56%), the sight of the injection needle (47%) and sitting at the treatment chair (42%) as especially fear provoking. As subjective elements of their fear, the patients reported muscle tension (64%), higher heart-beat (59%), accelerated breathing (37%), sweating (32%), and stomach cramps (28%). Among fearful patients, greater changes in pulse rate (>10 beats/min) and changes in blood pressure were measured. Oral health correlated with levels of fear only for younger patients. Although the frequency of caries (DMF/T) and the degree of treatment need (CPITN) showed a significant correlation (p >0.005) with subjective fear of treatment among patients under 35 years of age, the correlation weakens with increasing age of the patients studied. The present findings strongly suggest the need for more prophylactic measures, and dental education, in kindergartens and elementary schools. By such means, a considerable improvement in levels of oral hygiene might be achieved, together with lower levels of fear of dental treatment.

Two-photon near- and far-field fluorescence microscopy with continuous-wave excitation

We report on scanning far- and near-field two-photon microscopy of cell nuclei stained with DAPI and bisbenzimidazole Hoechst 33342 (BBI-342) with the 647-nm laser line of a cw ArKr mixed-gas laser. Two-photon-excited fluorescence images are obtained for 50-200 mW of average power at the sample. A nearly quadratic dependence of fluorescence intensity on laser power confirmed the two-photon effect. The nonlinearity was further supported by evidence of three-dimensional sectioning in a scanning far-field microscope. We find that the cw two-photon irradiation sufficient for imaging within typically 5 s does not significantly impair cell cycling of BBI-342-labeled live cells. Finally, high-resolution imaging in scanning near-field microscopy with good contrast is demonstrated.

Differential expression of two mRNA species indicates a dual function of peripheral myelin protein PMP22 in cell growth and myelination

Two peripheral myelin protein PMP22 transcripts, CD25 and SR13, have been identified by Northern blot and RNA-polymerase chain reaction (PCR) methods in rat. The CD25 and SR13 mRNA species (each approximately 1.8 kb in size) differ significantly in their 5'-untranslated region (5'-UTR) sequences but encode the same protein. While CD25 mRNA is largely confined to the peripheral nervous system, the SR13 transcript is more ubiquitously expressed in rat tissues. Both transcripts are differentially expressed during postnatal sciatic nerve development. While CD25 expression steadily increases from low levels in neonates up to a maximum at postnatal day 14, SR13 mRNA levels are elevated at birth but decrease throughout adulthood. CD25 and SR13 transcripts are expressed at very low constant levels in developing and adult brain. In degenerating and regenerating segments of injured peripheral nerve changes in CD25 mRNA levels clearly resemble the expression pattern of other myelin genes, whereas expression of SR13 is inversely correlated with the time course of Schwann cell proliferation. In cultured rat meningeal fibroblasts SR13 mRNA expression is strictly growth arrest-specific and independent of forskolin. On the other hand, regulation of CD25 mRNA levels in these cells is more complex with respect to interfering effects of serum and forskolin. In cultured Schwann cells neither CD25 nor SR13 expression is growth arrest-specific. However, both transcript levels are consistently enhanced by forskolin under all conditions of cell growth tested. Expression of CD25 (but not SR13) depends on high Schwann cell density. Our results substantiate the hypothesis that PMP22 serves two biological functions, one related to cell growth (SR13) and another to myelination (CD25).

Coexpression of PMP22 gene with MBP and P0 during de novo myelination and nerve repair

The recently cloned PMP22 gene, the rat variant of the murine growth arrest-specific gene gas3, encodes a new 22 kD integral membrane glycoprotein of peripheral myelin. By means of in situ hybridization and immunohistochemistry, we have (1) analyzed PMP22 expression in myelinated and nonmyelinated peripheral nerves, and (2) compared the spatio-temporal changes in the expression of PMP22 mRNA with the expression of the myelin genes P0 and MBP (myelin basic protein) in developing as well as degenerating and regenerating sciatic nerve of rat. (3) We further investigated the expression of PMP22 mRNA by Northern blot in cultured Schwann cells maintained under different conditions of cell growth and arrest. Expression of PMP22 mRNA is restricted to Schwann cells of myelinated peripheral nerve. Transection of sciatic nerve in adult rat leads to a simultaneous and rapid decline in both PMP22 and P0 mRNA to nondetectable levels in the degenerating distal stump. When a demyelinated and axon-free distal stump, as indicated by the lack of MBP and neurofilament immunoreactivity, was reanastomosed to its proximal counterpart, the coordinated reexpression of PMP22 and MBP succeeded axonal regeneration through the distal segment with a delay of 1-2 weeks. As in regenerating nerve, a striking synchrony of expression of PMP22 and P0 transcripts, as well as MBP immunoreactivity, could be observed during sciatic nerve development. Further, in vitro evidence suggests that, unlike NIH3T3-fibroblasts, expression of PMP22/gas3 is not strictly growth arrest-specific in Schwann cells.(ABSTRACT TRUNCATED AT 250 WORDS)