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Biomedical subjects

W R Boydston

Publications and source records attributed to W R Boydston.

12 recordsLinked to original sources
PubMed1995

Decision making in primary surgical repair of myelomeningoceles.

A 5-year review of 43 consecutive patients presenting to Scottish Rite Children's Medical Center with an open myelomeningocele defect was undertaken. The aim of the present study was to analyze the myelomeningocele defects, dimensions, and area to better define those factors that dictate the need for plastic surgical consultation for wound closure. Of the 43 patients identified, two were excluded because they first presented as older children; the remaining 41 all had their myelomeningoceles repaired within the first 36 hours of life. Of these, 31 underwent repair by the Neurosurgical Service, whereas for 10 patients (24.4%), the Plastic Surgery Service was asked to assist with closure. Comparison showed the mean (+/- standard deviation) area in the referred patients was 27.4 (7.6) cm2 versus 17.6 (7.9) cm2 in the patients not referred for closure (p = 0.002). A trend analysis predicting referral as a function of myelomeningocele area showed that 0 of 10 (0%) with an area of less than 15 cm2, 2 of 13 (15.4%) with an area equal to 15 to 20 cm2, 3 of 7 (42.9%) with an area of 21 to 25 cm2, and 4 of 9 (44%) with an area greater than 25 cm2 were referred (p = 0.001). Data from the interpretation of maximum myelomeningocele dimension also showed statistically significant trends in referral. Using multiple logistic regression, it was found that the odds of referral increased by a factor of 3.3 for every 1 cm increase in maximum dimension.

Decision Making↗
PubMed1994

Surgical correction of severe scaphocephalic deformities.

Sagittal synostosis may result in severe skull deformities. Characteristic components of the deformity include extreme elongation, frontal and occipital bossing, temporal pinching, and angulatory apical skull deformation. Conventional strip craniectomy often fails to correct these complex problems completely in severe early or late cases of sagittal synostosis. Techniques for total calvarial vault reconstruction have previously been reported, but a single large series has not been presented. Eighteen consecutive patients ranging in age from 3 months to 5 years (mean = 12 months) with severe early and late scaphocephalic skull deformities underwent total calvarial vault reshaping. All children required transfusions ranging from 250 to 1,100 mL. Operative times averaged 6 hours, and hospital stay ranged from 4 to 7 days. There was no perioperative mortality. Two patients experienced transient syndrome of inappropriate secretion of antidiuretic hormone, which responded to fluid restriction. One patient was noted to have a 2-cm parietal craniectomy defect 9 months after operation. Microscrews, which were used in all 18 patients, had to be removed in 2 patients when they became palpable. Excellent aesthetic results were noted in all 18 patients up to 36 months of follow-up.

Child, Preschool↗
PubMed1983

The role of epithelial cells in gut-associated immune reactivity.

Epithelial cells and their products are essential participants in both initial and final stages of reactivity to foreign materials in the gut lumen. Follicle-associated epithelial cells, called "M"-cells by others, more efficiently transport antigens from the lumen than do columnar absorptive cells. Epithelial cells degrade antigens intracellularly. The presence of Ia-like antigens on epithelial cells of the gastrointestinal tract and thymus suggests a role in antigen presentation. Actively phagocytic macrophages are present within the epithelium of Peyer's patches and appendix, providing antigen degradation and presentation. Follicle-associated epithelial cells transport materials from lamina propria into intestinal lumen. Therefore, FAE cells are capable of bidirectional transport. Plasma cells are located within and immediately beneath the epithelium of Peyer's patches and appendix, where defects in the basal lamina indicate diminished capability for molecular selection. Transmission of antibodies into the lumen would modulate further antigen uptake and provide for interaction with organisms.

Animals↗
PubMed1983

Decrease in acetylcholine receptor number correlated with increased naturally occurring trochlear motor neuron death during development.

It has been observed that daily application of neostigmine onto the chorioallantoic membrane drastically reduced the total number of acetylcholine receptors in the superior oblique muscle of duck embryos. Here the effects of neostigmine on the magnitude of naturally occurring death of trochlear motor neurons during embryonic development were investigated. There was an enhanced loss of neurons in the neostigmine-treated embryos. Neostigmine neither affected the initial production of normal numbers of motor neurons nor had any direct toxic effect on their ultrastructure. The decrease in muscle activity did not always correlate with increased motor neuron survival. There may be a relationship between acetylcholine receptor distribution and naturally occurring neuronal death.

Animals↗
PubMed1983

Architecture of human pancreas: implications for early changes in pancreatic disease.

An increased proportion of ductulelike structures, sometimes dilated, occurs in association with pancreatic adenocarcinoma, chronic pancreatitis, cystic fibrosis, and pancreatic ectasia associated with conditions such as uremia. This frequently is interpreted as ductular proliferation, implying origin in ductal elements. Recent animal studies have provided an altered view of pancreatic architecture that is consistent with acinar dedifferentiation leading to the ductulelike structures, or tubular complexes. The architecture of pancreas from organ donors was studied by light and scanning electron microscopy and by wax reconstruction of serial sections. It is concluded that the zymogen granule-containing cells of normal human exocrine pancreas are arranged as branching tubules that vary in diameter and curve acutely. The tubules frequently end blindly to form acinar structures; less frequently they anastomose. This arrangement is consistent with the interpretation that tubular complexes associated with pancreatic disease result from dedifferentiative changes in acinar cells. Tubular complexes may reflect a defect or defects common to pancreatic disease rather than ductular proliferation specific to each one.

Adolescent↗
PubMed1982

Origin of tubular complexes in human chronic pancreatitis.

Tissue samples from seven patients with chronic pancreatitis were studied by light and electron microscopy, using samples from the pancreas of seven organ donors as a reference group. Tubular complexes were observed in four of the patients with chronic pancreatitis. Tubular complexes, which have been interpreted as resulting from "ductular reduplication" in other studies of chronic pancreatitis, and "ductular proliferation" in studies of pancreatic adenocarcinoma, were studied carefully to determine their origin. Extensive retrogressive changes in acinar cells leading to diminished zymogen granules, decreased cell height, and concomitant increase in luminal diameter were consistent with the interpretation that phenotypic modulation of acinar cells to take on the characteristics of ductular cells produced the tubules. This it is concluded that in chronic pancreatitis, as has been shown for pancreatic adenocarcinoma, the tubular complexes originate from acinar cells rather than from proliferation of preexisting ductules. Fibrosis and thickening of the basal lamina of exocrine pancreatic cells and capillaries were consistent with an altered capability for transmission of material between blood vessels and exocrine cells.

Adult↗
PubMed1982

Influence of neostigmine treatment on embryonic development of acetylcholine receptors and neuromuscular junctions.

The postulated role of the acetylcholine receptor in the formation of neuromuscular synapses during the course of embryonic development was investigated in the superior oblique muscle of white Peking duck embryos. The possibility that the number of receptors could be experimentally lowered by chronic injections of the anticholinesterase agent, neostigmine methylsulfate, was determined using 125I-alpha-bungarotoxin. The total number of acetylcholine receptors on incubation day 12, 2 d subsequent to the onset of treatment, was reducted 45% as compared to saline-treated controls. A similar reduction in total receptor content (49%) was also observed on day 19. Radioautographic preparations showed that clusters of acetylcholine receptors were rare and that the grain density of extrajunctional receptors was also reduced. Hence, chronic treatment with neostigimine during development was observed to exert an effect on both the number and distribution of receptors in the developing superior oblique muscle. These changes occurred in the absence of any apparent effect on muscle differentiation in general. Myoblasts and myotubes were present on day 14 and further differentiated into myofibers by day 18 in both neostigmine and saline-treated muscles. The cytology of the develop;ing muscle cells also appeared normal. This is in contradistinction to the striking morphological changes that take place in adult mammalian and avian muscle after anticholinesterase treatment. More significantly, the decreased total receptor content and sparsity of clusters had no apparent effect on the formation of developing neuromuscular junctions at the electron microscopic level. The frequency of neuromuscular junctions in neostigmine-treated muscles was similar to that of the controls. It is concluded that acetylcholine receptor clusters are not required for the events leading to the morphological formation of neuromuscular junctions during in vivo development.

Animals↗
PubMed1982

Participation of follicle associated epithelium (fae), macrophages, and plasma cells in the function of appendix.

Rabbit appendix was studied by correlated scanning and transmission electron microscopy and light microscopy, taking advantage of luminal bacteria as naturally occurring markers for following antigen uptake. The three-dimensional relationship of lymphoid follicles to other structures was revealed clearly. The smooth luminal surface of the appendix is interrupted by stomata each leading to a recessed interval between the dome epithelium covering the apical pole of each follicle and the goblet cell-rich epithelium forming a cupola on the opposing surface. Bacteria abound in this recess. They are taken up by follicle associated epithelial (FAE) cells which comprise part of the dome epithelium. Intraepithelial macrophages phagocytize the bacteria. Bacteria-laden macrophages are numerous in the dome area of the follicle and in the germinal center. Large lymphatic sinuses surrounding the follicles are well visualized following stimulation of fluid movement. Plasma cells are located within the dome epithelial layer and immediately beneath it. Plasma cells may be concentrated along the base of epithelial cells, with the absence of a basal lamina indicating an absence of the molecular selection which it would normally provide. The appendix, like Peyer's patches, takes up antigens, processes them, and gives evidence of reaction to them locally, with the secretions from plasma cells possibly modulating antigen entry.

Animals↗
PubMed1979

Grafting of additional periphery reduces embryonic loss of neurons.

Effects of increased peripheral field of innervation on the magnitude of the spontaneously occurring embryonic cell death in the chick trochlear and isthmo-optic nuclei were examined. Grafting of an additional optic primordium and the surrounding mesoderm (which forms extraocular muscles) was performed at stage 11 (HH stage series). The grafted tissue is innervated by the appropriate neuron pool as revealed by the retrograde axonal flow of HRP. Cell counts of the trochlear nucleus on day 19 indicate a mean increase of 37% (range 19--62%) in the number of cells on the experimental side (contralateral to the graft) as compared to the ipsilateral control nucleus of the same embryos. Cell counts of the isthmo-optic nucleus on day 19 show an average increase of 35% (range 27--41%) on the experimental (contralateral) side over the ipsilateral control side. This increase in cell survival is not due to a stimulatory effect of grafting on cellular proliferation as revealed by the cell counts of trochlear and isthmo-optic nuclei on day 9 and 11 respectively. Thus, the increased cell survival is attributed solely to the reduction in the magnitude of the embryonic cell death. Whether this reduction in embryonic cell death is due to increased number of synaptic sites or increased amounts of trophic substances remains uncertain.

Animals↗
PubMedDate not supplied

Gliomas of the tectum and periaqueductal region of the mesencephalon.

Gliomas that arise in the tectal and periaqueductal region of the mesencephalon usually present with hydrocephalus secondary to occlusion of the aqueduct of Sylvius. A review of 486 brain tumors in children treated during a 5-year period revealed 6 children with gliomas of the tectal plate. The 6 children were shunted for hydrocephalus, presumed secondary to aqueductal stenosis, prior to establishing the diagnosis of tectal plate glioma. No abnormalities were noted on the initial, uncontrasted computed tomography (CT) scans. The tumors are isodense without contrast enhancement which makes the CT diagnosis difficult. Magnetic resonance imaging (MRI) is diagnostic and demonstrates the characteristic enlargement of the tectum with increased density on T2 images. T1 density and gadolinium enhancement are variable. Pathological confirmation was obtained by open biopsy in 2 patients, a stereotaxic biopsy was performed on 2 children; 2 children were not biopsied. The tumor histology obtained was that of pilocytic astrocytoma. Two patients were treated with radiation therapy at the time of diagnosis. One child was followed closely and subsequently irradiated after tumor progression. All patients in this series are alive and functioning adequately 2-10 years after the onset of symptoms.

Adolescent↗