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Biomedical subjects

D Drucker

Publications and source records attributed to D Drucker.

7 recordsLinked to original sources
PubMed1992

The development of parafoveal and mid-peripheral human retina.

The morphological development of parafoveal retina (1-1.5 mm from the foveal center) and the mid-peripheral (4 mm from the foveal center) human retina has been studied from fetal (F) 26 weeks to adulthood. At both retinal points, all layers and neuronal types are present at F26 weeks. In parafovea at F26 weeks photoreceptors have only a rudimentary inner segment and no outer segments. Short outer segments are present on both rods and cones at F36 weeks. By postnatal (P) 5-8 days the inner retina is relatively mature. Photoreceptors have elongated basal axons which cause the photoreceptor layer to become much thicker than in prenatal retina. At birth cone inner segments are untapered, but rod inner segments have already reached their adult width of 2 microns. Both rod and cone inner and outer segments are 30-50% of adult length. By 13 months both inner and outer retina are mature appearing, with the photoreceptors accounting for half the retinal thickness due to the elongation of the fibers of Henle. Cone outer segments elongate up to P5 years and rod outer segments to P13 years. At mid-peripheral or rod-ring retina outer segments are present on rods at F26 weeks and on cones at F36 weeks. At birth the inner retina is adultlike. The outer plexiform layer becomes thicker up to P45 months due to the elongation of fibers of Henle. At birth both rod and cone mid-peripheral inner segments are slightly longer and outer segments are 50% longer than in parafoveal retina. By P5 years mid-peripheral rod outer segments are slightly longer than in parafoveal retina, and this changes little thereafter. This anatomical study has found that the photoreceptors in peripheral rod-ring retina develop earlier than those in more central retina, and in turn parafoveal photoreceptors develop well in advance of foveal cones. This suggests that human neonates may utilize more peripheral retinal regions for some aspects of visual function before foveal cone vision becomes dominant.

Adolescent↗
PubMed1992

Revision of the acetabular component with an uncemented Harris-Galante porous-coated prosthesis.

One hundred and forty revisions for loosening of the acetabular component were performed in 124 patients, with the use of an uncemented Harris-Galante acetabular prosthesis. A component was considered loose if there was a change in its position or vertical or horizontal migration, or both, of four millimeters or more, as demonstrated on serial radiographs. All patients were followed prospectively for a mean of forty-one months (range, twenty-four to seventy-six months). Bone-grafting was performed at the time of the revision in 127 of the hips. Identifiable failure of fixation of the acetabular component occurred in only two hips (1 per cent), which had both severe acetabular bone loss and pelvic discontinuity. In one of these hips, fixation of the component could not be achieved during the revision, and the component subsequently migrated. No other components migrated. Only one patient had a revision of the index acetabular operation. A continuous radiolucency developed at the bone-mesh interface of five acetabular components, and in one other hip a small portion of the mesh separated. This hip was reoperated on for a problem with the femur, and the socket was found to be rigidly fixed. No other evidence of loosening was identified. All of the bone grafts united, but partial resorption of the graft occurred in thirty-nine hips. Although there were substantial osseous defects that necessitated major bone-grafting, revision with the uncemented Harris-Galante porous-coated acetabular component provided superior fixation compared with that reported in other series in which cemented acetabular components were used for revision. Of the 140 hips, eighty-nine (64 per cent) had a postoperative score of good or excellent, according to the Harris hip-rating system. Twenty-eight (70 per cent) of the forty hips that had revision of the acetabular component alone were rated as good or excellent.

Acetabulum↗
PubMed1986

Adrenocortical dysfunction in acute medical illness.

To further characterize the adrenocortical response to acute illness, we measured basal and adrenocorticotropic hormone (ACTH)-stimulated 11-deoxycortisol, androstenedione, and dehydroepiandrosterone sulfate (DHEAS). Acutely ill patients had higher ACTH-stimulated 11-deoxycortisol and androstenedione, and decreased basal and ACTH-stimulated androstenedione/cortisol and DHEAS/cortisol ratios. Our data suggest that a shift away from androgen synthesis toward the glucocorticoid pathway occurs in acute illness.

Acute Disease↗
PubMed1985

Variable adrenocortical function in acute medical illness.

Acute medical illness may produce dramatic changes in endocrine function. Although cortisol levels rise in acute medical illness, changes in adrenocortical function and reserve have not been well documented in medical ICU patients. We evaluated plasma ACTH and cortisol levels, and cortisol response to intravenous ACTH in 40 acutely ill patients and 20 anxious but nonacutely ill controls. A wide range of plasma cortisol values (212 to 8430 nmol/L) was observed. More severely ill patients did not necessarily have higher plasma cortisol values. Patients who survived hospitalization had lower mean initial and post-ACTH cortisol levels than patients who succumbed. ACTH levels varied widely and correlated poorly with levels of plasma cortisol. There was no evidence of occult adrenocortical insufficiency. We conclude that plasma cortisol elevations are common in acute medical illness.

Acute Disease↗
PubMed1985

Inappropriate TSH secretion with abnormal thyrotroph sensitivity to dopamine.

A 47-year-old male schizophrenic with hyperthyroidism was found to have non-neoplastic inappropriate thyrotropin (TSH) secretion. Anterior pituitary function, CT scan and alpha subunit determinations were normal. TSH rose after TRH (7.8 to 22.5 microU/ml) and propylthiouracil (26.1 microU/ml after 3 months) and decreased with oral T3 (Cytomel 25 micrograms po q.i.d.). Cytomel and glucocorticoid infusion blunted but did not completely suppress the TSH response to TRH. Intravenous dopamine infusion (4 micrograms/kg/min) completely suppressed the prolactin but not the TSH response to TRH. The association of schizophrenia and differential thyrotroph sensitivity to dopamine suggests a possible role for dopamine in the pathogenesis of selected cases of non-neoplastic inappropriate TSH secretion.

Dopamine↗