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Biomedical subjects

D Bader

Publications and source records attributed to D Bader.

At least 91 records · Page 5Linked to original sources
PubMed1982

Immunochemical analysis of myosin heavy chain during avian myogenesis in vivo and in vitro.

Monoclonal antibodies (McAbs) against the myosin heavy chain (MHC) of adult chicken pectoralis muscle have been tested for reactivity with pectoralis myosin at selected stages of chick development in vivo and in vitro. Three such McAbs, MF 20 and MF 14, which bind to light meromyosin, and MF 30, which binds to myosin subfragment two (S2), were used to assay the appearance and accumulation of specific MHC epitopes with: (a) indirect, solid phase radioimmune assay (RIA), (b) immunoautoradiography, (c) immunofluorescence microscopy. McAb MF 20 bound strongly and equivalently to MHC at all stages of embryonic development in vivo. In contrast, the MF 30 epitope was barely detectable at 12 d of incubation but its concentration rose rapidly just before hatching. No detectable binding of MF 14 to pectoralis myosin could be measured during myogenesis in vivo until 1 wk after hatching. Immunofluorescence studies revealed that all three epitopes accumulate in the same myocytes of the developing pectoralis muscle. Since all three McAbs bound with high activity to native and denatured forms of myosin, it is unlikely that differential antibody reactivity can be explained by conformational changes in myosin during development in vivo. When myogenesis in vitro was monitored using the same McAbs, MF 20 bound to the MHC at all stages tested while reactivity of MF 30 and MF 14 with myosin from cultured muscle was never observed. Thus, this study demonstrates three different immunochemical states of the MHC during development in vivo of chick pectoralis muscle and the absence of later occurring immunochemical transitions in the MHC of cultured embryonic muscle.

Animals↗
PubMed1981

Density and distribution of alpha-bungarotoxin-binding sites in postsynaptic structures of regenerated rat skeletal muscle.

Acetylcholine receptors (AChR) are organized in a discrete and predictable fashion in the postsynaptic regions of vertebrate skeletal muscle. When muscle is damaged, nerves and myofibers including muscular elements of the endplate degenerate, but the connective tissue elements survive. Muscle fibers regenerate within the basal lamina of the original myofiber. Postsynaptic differentiation in regenerated mammalian skeletal muscle can occur in different ways: (a) at the site of the original endplate in the presence or absence of the nerve, or (b) at ectopic regions of the regenerated myofiber in the presence of the nerve when the original endplate is not present. The present study used (125)I-alpha- bungarotoxin ((125)I-alpha-BuTX) and EM autoradiography to examine the density and distribution of AChR in postsynaptic structures regenerated at the site of the original endplate in the absence of the nerve and at ectopic sites of the myofiber in the presence of the nerve when the original endplate was removed. In regenerated myofibers, the density of alpha-BuTX-binding sites fell within the range of densities observed in uninjured muscle whether postsynaptic differentiation occurred at the site of the original endplate in the absence of the nerve or at an originally ectopic position of the regenerated myofiber. In addition, the distribution of alpha-BuTX-binding sites within the regenerated postsynaptic regions closely resembled the distribution of apha-BuTX- binding sites in uninjured muscle. Morphometric analysis was performed on postsynaptic structures formed at the site of the original endplate in the absence of the nerve or at an ectopic position of the regenerated myofiber by interaction of the nerve and muscle. Although variation in the depth of the primary cleft occurred, there was little difference between the overall structure of regenerated postsynaptic structures and that of endplates of uninjured muscles.

Animals↗
PubMed1980

The prevalence of refractive and ocular anomalies among 1242 institutionalized mentally retarded persons.

The population of a large Canadian institution, providing rehabilitative and health care for the mentally retarded, received oculo-visual assessments in an optometric clinic established in the hospital by the University of Waterloo, School of Optometry. The ocular and visual anomalies of 1242 residents have been compiled and analyzed. This paper reports the results and discusses their implications. The size of the sample makes the data useful in planning vision care delivery to the mentally retarded. Comparisons are made to similar data obtained from a concurrent study of a community sample and to studies from vision literature.

Adolescent↗
PubMed1980

The effects of corrective lenses on various behaviors of mentally retarded persons.

A questionnaire was developed to measure changes in certain behaviors at various intervals after correction of refractive errors in a sample of mentally retarded persons. The sample comprised three age groups: 0 to 6 years, 7 to 17, and 18 and above. In each age group, four subgroups were selected--one experimental (new-glasses) group and three control groups. In the group which received new spectacles, changes were recorded in social behaviors, gross and fine motor skills, and reading and writing skills. These changes were most evident in the youngest age group.

Adolescent↗
PubMed1979

Autoradiographic and electron microscopic studies of minced cardiac muscle regeneration in the adult newt, notophthalmus viridescens.

The regenerative response of minced cardiac muscle grafts in the adult newt was studied using autoradiography and electron microscopy. One-sixteenth to one-eighth of the newt ventricle was amputated, minced, and returned to the wounded ventricle. At five days after grafting, no reorganization of graft msucle pieces was apparent and there was degeneration of much of the muscle graft. Another, smaller population of 5-day myocytes had euchromatic nuclei and intact sarcolemmae. In 10- and 16-day grafts, continuity between ventricular and graft lumina was established and coalescence of graft pieces was apparent. Ultrastructurally, 10- and 16-day graft myocytes appeared to have fewer myofibrillae and increased amounts of rough endoplasmic reticulum, polyribosomes, Golig complexes, and dense bodies when compared to uninjured ventricular myocytes. The peak of proliferative activity of graft cells was observed at 16 days. Electron microscopic autoradiography revealed breadkdown of myofibrillar structure in labeled myocytes, whereas in myocytes in the later stages of mitosis only scattered myofilaments and no Z bands were present. By 30 days, grafts appeared as an integrated structure composed primarily of cardiac muscle. Myocytes of 30-day grafts were observed in various stages of myofibrillogenesis and contained numberous 10-nm filaments. Seventy-day graft mycoytes had numberous well organized myofibrillae and intercellular junctions similar to those seen in uninjured ventricular myocytes.

Animals↗
PubMed1977

Fever: genuine or factitious?

Although patients with factitious fever form a small subgroup of all patients investigated for fever of unknown origin, the diagnosis should be kept in mind. If unsuspected, this phenomenon can lead to a multiplicity of laboratory investigations and misuse of hospital beds, as well as to unnecessary risk to the patient.

Adolescent↗
PubMedDate not supplied

Two zinc fingers of a yeast regulatory protein shown by genetic evidence to be essential for its function.

The best-understood protein structure involved in DNA binding is the helix-turn-helix motif. A second DNA-binding domain, the finger structure, has been proposed on the basis of sequence analysis, partial proteolysis and zinc content of Xenopus transcription factor TFIIIA. Other eukaryotic proteins were subsequently found to contain contiguous repeat units of the postulated finger motif. Each repeat unit contains thirty amino acids and is thought to bind a zinc atom using two cysteines and two histidines as ligands. The protein loop or finger between apparent zinc ligands is rich in DNA-binding residues and is thought to make specific contacts with DNA. The yeast protein ADR1, a positive regulator of transcription of the gene ADH2, contains two finger domains in a region of the protein required for transcriptional activation. Nineteen independently isolated adr1 mutations induced by hydroxylamine were found at nine different amino-acid positions, seven of which are in the two finger domains. All four mutations that altered invariant cysteine or histidine residues led to an adr1 null phenotype. Only one other mutation caused an adr1 null phenotype. Thus, one finger domain is not sufficient for ADR1 activity. This provides the first evidence that, as is consistent with the proposed model, the invariant cysteine and histidine residues are essential for the formation of the finger structure.

Amino Acid Sequence↗
PubMedDate not supplied

Hyaluronan, heterogeneity, and healing: the effects of ultrapure hyaluronan of defined molecular size on the repair of full-thickness pig skin wounds.

The extracellular matrix macromolecule, hyaluronan, is thought to modulate wound healing. However, the molecular size of hyaluronan and contaminating associated proteins may be important determinants of these effects. We have examined the results of seven daily topical treatments of full-thickness skin wounds in pigs with ultrapure hyaluronan of defined molecular size. High molecular weight hyaluronan (>1000 kd) enhanced, whereas low molecular weight hyaluronan decreased, the rate of early wound contraction as compared with intermediate hyaluronan (molecular weight = 100 kd) and saline solution controls. Fracture strength at 21 days was reduced by high and intermediate molecular weight hyaluronan but not by low molecular weight hyaluronan. Wound perfusion, measured by means of a scanning laser-Doppler technique as a noninvasive indicator of angiogenesis, showed depression by high and intermediate molecular weight hyaluronan on day 3, but all forms of hyaluronan caused elevated blood flow on day 7. The architecture of granulation tissue in this wet healing model was highly organized, but no gross histologic differences were seen because of treatment. Different molecular species of hyaluronan have differential effects on contraction, angiogenesis, and the evolution of wound strength. Where hyaluronan is used as a treatment or vehicle for wounds, its precise composition should be specified.

Journal Article↗
PubMedDate not supplied

Genital prolapse in a preterm female infant.

Genital prolapse in the female infant during the neonatal period is relatively rare and is usually associated with anomalies of the central nervous system. A case of vaginal prolapse in a small-for-gestational-age preterm female infant, without any associated nervous system anomalies, is presented. The clinical presentation, diagnostic approach, management, and outcome of the case are discussed with reference to a review of the literature.

Female↗
PubMedDate not supplied

The effect of maternal smoking during pregnancy on sleep respiratory and arousal patterns in neonates.

Ten term infants who were exposed to maternal smoking during pregnancy and 10 age- and sex-matched control infants participated in the study. At the age of 48 hours (+/- 10), all infants underwent a 150- to 200-minute polygraphic study in a soundproof laboratory. Respiratory and heart rates, distribution of sleep states, and oxygen saturation were comparable in the two groups. The number and length of apneic events were similarly distributed in the two groups. The proportion of obstructive apneic events followed by arousal was significantly higher in the control group especially during quiet sleep (p = 0.001). It appears that exposure to smoking during pregnancy is associated with a higher arousal threshold in term infants. This finding could be of relevance in the assessment of maternal smoking as a risk factor for sudden infant death syndrome.

Apnea↗
PubMedDate not supplied

Bilateral ureteral atresia.

Congenital, bilateral, distal ureteral atresia with severe renal dysplasia in a preterm infant is presented. This rare anomaly is caused by a variable degree of failure of the ureteral bud development. Prognosis is usually dependent on the severity of the obstruction.

Abnormalities, Multiple↗