Response surface methodology of nitrilase production by recombinant Escherichia coli

Growth and nitrilase production by recombinant Escherichia coli cells harbouring pET 21 (b) plasmid, for the expression of Pseudomonas putida nitrilase were improved using response surface methodology. Central composite design was used for obtaining ideal concentration of critical medium components which include fructose, tryptone, yeast extract and lactose. The optimal values for the concentration of fructose, tryptone, yeast extract and lactose were found to be 1.13, 2.26, 3.25 and 0.9 percent (w/v), respectively. Here, fructose served as carbon source for the growth while lactose was preferably used as inducer for the expression of foreign protein. Yeast extract in the medium was used as a growth promoter while tryptone was added as a major nitrogen source. Using this optimized medium, an experimental growth of 6.67 (OD at 600 nm) and nitrilase activity of 27.13 U/ml was achieved. This approach for medium development led to an enhancement of the growth and enzyme activity by 1.4 and 2.2 times, respectively, as compared to the un-optimized medium.

Periorbital melanosis is an extension of pigmentary demarcation line-F on face.

BACKGROUND: To date, periorbital melanosis is an ill-defined entity. The condition has been stated to be darkening of the skin around the eyes, dark circles, infraorbital darkening and so on. AIMS: This study was aimed at exploring the nature of pigmentation in periorbital melanosis. METHODS: One hundred consecutive patients of periorbital melanosis were examined and investigated to define periorbital melanosis. Extent of periorbital melanosis was determined by clinical examination. Wood's lamp examination was performed in all the patients to determine the depth of pigmentation. A 2-mm punch biopsy was carried out in 17 of 100 patients. RESULTS: In 92 (92%) patients periorbital melanosis was an extension of pigmentary demarcation line over the face (PDL-F). CONCLUSION: Periorbital melanosis and pigmentary demarcation line of the face are not two different conditions; rather they are two different manifestations of the same disease.

Inducing repigmentation by regrafting and phototherapy (311 nm) in punch grafting failure cases of lip vitiligo: a pilot study.

BACKGROUND: Punch grafting followed by PUVA/PUVASOL is an established mode of therapy in vitiligo including that on the lips. AIMS: To assess the efficacy of NB-UVB along with regrafting in patients in whom punch grafting had failed to evoke any response. METHODS: Five patients with stable and isolated lip vitiligo in whom punch grafting and PUVA had failed to produce pigmentation were treated by regrafting and subsequent NB-UVB (311 nm) phototherapy. RESULTS: Complete repigmentation was observed in three of the five cases after 16 weeks. In the remaining two, the results were mixed. CONCLUSIONS: Stable lip vitiligo usually responds very well to punch grafting and PUVA/PUVASOL. In patients who fail to respond to this treatment, complete repigmentation following regrafting and NB-UVB is an observation that needs to be explained.