Genetic association analysis of KCNQ3 and juvenile myoclonic epilepsy in a South Indian population.

Juvenile myoclonic epilepsy (JME) is a common subtype of idiopathic generalized epilepsy that shows a complex pattern of inheritance. We have tested the association between JME phenotype and an intragenic marker in KCNQ3 by using the transmission disequilibrium test in 119 probands and their parents. Mutations in KCNQ3 are known to cause benign familial neonatal convulsions and are involved in the physiologically important M current in neurons. Our results provide suggestive evidence of allelic association between JME and KCNQ3 ( P-value=0.008) and raise an interesting possibility of a genetic contribution to JME, viz., of a gene that causes a monogenic form of human epilepsy.

Preparation of enantiomerically pure L-7-azatryptophan by an enzymatic method and its application to the development of a fluorimetric activity assay for tryptophanyl-tRNA synthetase.

The reaction of D,L-7-azatryptophan (D,L-7AW) with tryptophanyl-tRNA synthetase (TrpRS), adenosine triphosphate (ATP), and Mg2+ in the presence of inorganic pyrophosphatase results in the formation of a highly fluorescent l-7AW-adenylate complex. Detection of this complex is based on its enhanced fluorescence at 315 nm excitation and 360 nm emission after the addition of ATP. This stereoselective reaction was used to develop an activity assay for TrpRS using commercially available racemic D,L-7AW. The assay can be used to determine the activity of TrpRS from samples which contain less than 1 nmol of enzyme in 250 microL of sample. Thus the enzyme activity can be assessed without resorting to a radioactive assay of tRNATrp acylation. A secondary use of the stereoselective assay was for confirming the presence of pure L-7AW, D-7AW, or mixtures of the two enantiomers. D-7AW and L-7AW were prepared by reacting D,L-7AW with chloroacetic anhydride to form N-chloroacetyl-D,L-7AW (ClAc-7AW) followed by stereospecific proteolytic digestion of ClAc-7AW using carboxypeptidase A to produce the free L-7AW. The L-7AW could be separated from unreacted N-chloroacetyl-7AW by reverse-phase HPLC. The TrpRS-based assay was able to unambiguously discriminate between the two enantiomers of 7AW. The assay was then used to identify which enantiomer of 7AW was present in resolved fractions of the tripeptide L-lysyl-D,L-7-azatryptophyl-L-lysine. Digestion of the resolved tripeptides with protease enzymes produced the free L or D enantiomer of 7AW, which was easily identified using the TrpRS assay procedure.

Multizone photorefractive keratectomy for myopia of 8 to 23 diopters.

Multizone photorefractive keratectomy (PRK) was performed on 124 eyes of 69 patients for the treatment of high myopia using 4.5 mm, 5.0 mm, and 6.0 mm diameter ablation zones. Preoperative spherical equivalent refractions ranged from -8.00 diopters (D) to -22.5 D (mean +/- SD, -12.3 +/- 3.9 D). Mean attempted ablation depth was 109.5 +/- 37.8. Follow up ranged from 6 to 9 months. An uncorrected visual acuity of 20/60 or better was achieved in 63% of eyes and 20/40 or better in 48% of eyes. Sixty-seven percent of eyes achieved their pretreatment spectacle corrected visual acuity or were within two Snellen lines of it at 6 months postop. Subepithelial haze was mild in 23% of eyes and moderate in another 34% of eyes. This cleared without a trace in almost all of these eyes within 6 months. Twenty-five percent of the eyes had dense scars and required reablation.

Increasing the number of photorefractive keratectomy procedures from a single excimer laser gas fill.

Excimer laser ablative procedures are an expensive proposition for both the patient and the user. The high capital expenditure and the cost of consumables, notably the argon-fluoride gas, makes it imperative to achieve maximum utilization in terms of number of cases treated per fill of gas. This is particularly true in countries like India. The maximum number of cases can be treated by understanding not only the limitations of each fill of gas, but by proper patient scheduling and modifications to the treatment protocol. This paper outlines our modified protocol and the patient scheduling software that we developed to meet these criteria.

Retinopathy in tropical pancreatic diabetes.

In a study of the retinopathy profile of 40 patients with tropical pancreatic diabetes, a form of secondary diabetes seen in tropical countries, diabetic retinopathy was detected in 13 patients. Ten patients had background retinopathy and three patients had proliferative retinopathy requiring laser photocoagulation. In two patients, fibrous retinitis proliferans was present. Three patients had evidence of diabetic maculopathy. To our knowledge, this is the first report of severe and sight-threatening retinopathy occurring with secondary diabetes. Retinopathy in these forms of diabetes has hitherto been considered to be rare or, if present, only of a mild background type.

A new system of microsurgery for human and experimental corneal graftin. I. The contact lens corneal cutter, stereotaxic eye holder, donor disc chuck, and frame.

A new microsurgical system is presented for human and experimental corneal grafting. The system is based on novel methods of corneal cutting and holding which simplify collection procedures and minimise operator manipulation during transplantation.

A new system of microsurgery for human and experimental corneal grafting. II. Clinical and experimental applications.

After preliminary testing with pig, dog, rabbit, monkey, cat, and human cadaver eyes the CLCC system has been used for penetrating and lamellar keratoplasty in human subjects. Clinical experience covers a broad range of corneal pathology. Detailed operative instructions and observations are given. In the experimental situation the CLCC is being used to achieve deep lamellar corneal dissection for a continuing study of non-penetrating keratoplasty.