Biomedical subjects
Publications and source records attributed to R Koster.
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In vertebrates, pattern formation in the eye, central nervous system, somites, and limb depends on hedgehog activity, but a general target gene controlled by hedgehog in all these signaling centers has remained largely elusive. The medaka fish gene spalt encodes a zinc-finger transcription factor, which is expressed in all known hedgehog signaling centers of the embryo and in the organizer region at the midbrain-hindbrain boundary. We show that the spalt expression domains expand in response to ectopic hedgehog activity and narrow in the presence of protein kinase A activity, an antagonist of hedgehog signaling, indicating that spalt is a hedgehog target gene. Our results also suggest a signaling mechanism for anterior-posterior patterning of the vertebrate brain that controls spalt expression at the midbrain-hindbrain boundary in a protein kinase A dependent manner likely to involve an unknown member of the hedgehog family.
The potential use of an alternating treatment strategy with nevirapine and zidovudine in prolonging the antiretroviral effects of nevirapine was evaluated. Ten human immunodeficiency virus type 1 (HIV-1)-infected p24 antigen-positive persons who had not received prior antiretroviral therapy were treated for 9-13 weeks with an alternating regimen of 1 week of nevirapine (200 mg/day) and 3 weeks of zidovudine (600 mg/day). Serum p24 antigen levels declined during the first week of nevirapine treatment (median, 59%); however, subsequent courses of nevirapine were characterized by rising p24 antigen levels, while antigen levels remained stable or declined during zidovudine treatment. Serum beta 2-microglobulin levels and CD4+ cell counts exhibited similar responses. HIV-1 isolates obtained from 2 patients revealed 40- and 1000-fold reductions in nevirapine sensitivity after 8 weeks. These findings demonstrate that alternating treatment with zidovudine and nevirapine does not prolong the effectiveness of nevirapine and does not prevent the development of nevirapine resistance.
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Forty patients with hypotony during retinal detachment surgery were treated with intravitreal Healon. Healon was very well tolerated, except for a transient rise in the intra-ocular pressure in 19 out of 40 patients. A relationship between the rise in intra-ocular pressure and the mount of Healon used was not found. Temporal corneal decompensation occurred in two patients. Early cases of proliferative vitreo-retinopathy with retinal detachment were treated successfully with external retinal-detachment surgery and intravitreal Healon.
Eighteen consecutive patients with proliferative vitreoretinopathy following retinal detachment were treated with radical pars-plana vitrectomy and silicone oil injection. At least 6 months follow-up demonstrated fully attached retinas in 12 patients, partly attached retinas in 3 patients and primary failure in 3 patients. The visual fields revealed serious defects in 50% of those patients with attached retinas. The expected complications such as cataract (100%), glaucoma, corneal decompensation and subretinal oil were seen as well, but the complication rate is expected to diminish with newer surgical techniques.
Ten rabbits underwent vitreous aspiration and replacement by either Healon or Hydroxy Propyl Methyl Cellulose 2%. Four weeks' observation did not reveal noticeable differences between Healon and HPMC with regard to anterior chamber reaction, intra-ocular pressure or cataract. The vitreous reaction in eyes with HPMC was much more severe than in Healon eyes, with typical white precipitates and vitreous bands. Post-mortem examination confirmed the clinical findings.
A case history of a newborn infant is discussed. At birth he showed bilateral buphthalmos with aniridia and congenital corneal opacities, agreeing with Peters' anomaly. A keratoplasty was performed. The dysgenesis mesenchymalis classification is mentioned briefly. High resolution banding technique of chromosomes revealed no abnormality.
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