A phosphatidylinositol 4-kinase (Ptdlns 4-kinase, M(r) approximately 95,000) from the membranes of the electric organ of Torpedo californica was purified to apparent homogeneity. The Michaelis constant for ATP (KM = 280 +/- 60 microM at 20 degrees C) and the inhibition constant for adenosine (Ki = 0.4 mM at 20 degrees C) qualify the electrocyte Ptdlns 4-kinase as a type III kinase. The Ptdlns 4-kinase phosphorylates preferentially exogenous Ptdlns, added in the form of mixed Ptdlns/Triton X-100 micelles, whereas endogenously bound Ptdlns in the membrane fragments of electrocytes is a very poor substrate. It is important that the enzyme and the substrate Ptdlns are situated in different lipid bilayers. The catalytic turnover constant for exogenous Ptdlns is k = 55.3 +/- 6 min-1 at 20 degrees C and the molar Triton X-100/Ptdlns ratio of 16:1. For the substrate Ptdlns in the 'micellar solvent' Triton X-100, steady state kinetics were analysed in terms of the mole fraction X = n(Ptdlns)/[n(Ptdlns) + n(Triton X)] yielding the characteristic Michaelis mole fraction XM = 0.019 +/- 0.005 at 20 degrees C. The activity of the enzyme was enhanced about 5-fold in the presence of Triton X-114, yielding k = 277 +/- 30 min-1 at 20 degrees C. Triton X-114 has a shorter head-group, indicating that the vicinity of the Ptdlns head group in the mixed micelles should not be screened by bulky neighbours. The inhibition of the enzyme activity by Ca2+ is highly cooperative yielding the Hill inhibition constant Ki = 0.47 +/- 0.1 mM and the Hill coefficient h = 3.6 +/- 0.5. The enthalpy of activation is 100 +/- 10 kJ/mol between 0 degree C and 20 degrees C. Although the Ptdlns 4-kinase can be affinity-chromatographically copurified with the nicotinic acetylcholine (AcCho) receptor, suggesting tight association between the two proteins. AcCho does not affect the activity of the Ptdlns 4-kinase in the presence of the AcCho receptor.

1-Phosphatidylinositol 4-Kinase↗

PubMedDate not supplied

Ophthalmic screening of 38,000 children, age 1 to 2 1/2 years, in child welfare clinics.

Screening of 38,000 infants, age 1 to 2 1/2 years, showed a prevalence of 1.3% of strabismus and 0.5% of strabismic amblyopia. Esotropia was more than three times as frequent as exotropia. Approximately half of the cases with esotropia were amblyopic. Eighty-one percent of the cases with exotropia were intermittent, and in 29% the V-pattern was found. Significant ametropia was found in over 50% of the cases with strabismus. Although hypermetropia was the most frequent refraction in children with esotropia, myopia was a frequent finding in both esotropia and exotropia. Anisometroia was particularly frequent in constant unilateral esotropia. Accommodative strabismus was found in 7% of cases with infantile esotropia. In cases with paralytic strabismus, the most frequent muscle involved was the lateral rectus. Significant organic pathology, other than strabismus or amblyopia, was revealed in 0.2% of the series. "Rapid retinoscopy" through undilated pupils is an efficient method in detecting high refractive errors and candidates for nonstrabismic amblyopia in childhood. Since this method of examination is easy to perform, its adoption as a part of screening projects in childhood is recommended. "Rapid retinoscopy" performed by a trained orthoptist is also a useful method for detecting opacities in the ocular media.

Amblyopia↗

PubMedDate not supplied

Outcome of treatment of marked ametropia without strabismus following screening and diagnosis before the age of three.

Following early treatment of 39 consecutive cases with marked ametropia without strabismus, diagnosed by screening at the age of one to two and a half years, residual amblyopia was found in 20 (51%), including six (15%) with bilateral amblyopia, but with relatively good visual acuity in at least one eye. Anisometropia showed the highest rate of residual amblyopia. The main changes in refraction that occurred from the age of screening to the age of seven years was myopisation, especially in hypermetropic eyes without amblyopia. Heterotropia, always intermittent, developed in six of the 39 cases. Full stereopsis could be found in eight cases only, all without amblyopia. The majority, whether amblyopic or not, had partial binocular functions but four cases, all amblyopic, had none.

Amblyopia↗

PubMedDate not supplied

Prevention of strabismic amblyopia of early onset with special reference to the optimal age for screening.

Of 78 consecutive cases with constant unilateral esotropia diagnosed during screening and treated from the ages of seven months to three years, 82% ended up with visual acuity of 6/12 or better toward end of active treatment at the age of six to eight years. Of the cases with visual acuity of 6/12 or better at the end of treatment, 59% retained their vision when re-examined four to ten years later. The most important single parameter for the achievement of normal visual acuity was age of onset of treatment below two years and for long-term stability of the result this age dropped to 18 months. Initial large angles of esotropia had better prognosis probably because they were associated with an earlier onset of treatment. Poor prognosis was associated with faulty or no fixation of the esotropic eye when first diagnosed, with the failure to achieve alternation and with marked ansiometry. The optimal age for screening for strabismic amblyopia was suggested to be 12-18 months.

Age Factors↗

PubMedDate not supplied

[Analysis of cases of late syphilis in Poznań and the Poznań Province in the years 1965-1974 as a function of previous treatment].

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Adult↗