Biomedical subjects
P E Palmer
Publications and source records attributed to P E Palmer.
Toxoplasmosis.
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MPP+ induced apoptotic cell death in SH-SY5Y neuroblastoma cells: an electron microscope study.
PD is a common, late-onset neurodegenerative disorder that results in part from the gradual loss of dopaminergic neurons in the substantia nigra pars compacta. The neurotoxin MPTP can induce PD-like clinical symptomatology and neuropathological destruction and, thus, has been used as a PD model. The human neuroblastoma cell line SH-SY5Y possesses many of the qualities of human neurons and, as such, has served as a model for them. Apoptosis is the mode of cell death induced in SH-SY5Y cells by MPTP, and this was confirmed with nick end labeling and bisbenzimide staining. Transmission electron microscopic analysis of the ultrastructural changes occurring in neurotoxin exposed SH-SY5Ys revealed many morphological characteristics consistent with apoptosis. These changes included plasmalemmal blebbing, altered cytosolic density, nuclear condensation and fragmentation, pronounced vacuole formation, ribosomal dispersion, and the disappearance of the golgi complex, microtubules, and smooth endoplasmic reticulum. Limited amounts of rough endoplasmic reticulum and mitochondria exhibited normal morphology throughout the apoptotic changes but then were disrupted during secondary necrotic changes. The in vitro induction of apoptosis by a parkinsonism neurotoxin might be reflective of the mechanisms of in vivo nigral degeneration occurring during PD.
The challenge of international radiological education. The First Antoine Béclère Lecture of the International Society of Radiology, Beijing, China, 1996.
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The accessory optic system in the frog, Rana Pipiens: an electron microscopic study of the retinal afferents utilizing the anterograde tracer biocytin.
The retinal afferents to the basal optic nucleus in the frog, Rana Pipiens, were labeled anterogradely with biocytin and subsequently studied at the electron microscopic level. Labeled synaptic terminals in the nucleus varied in size from 0.5 microns to 2.0 microns and made symmetric synaptic contacts with large and small dendrites, although very rare axospinous and axosomatic contacts were also demonstrated.
The town where Roentgen was born.
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Degeneration of long-term fetal neostriatal allografts in the rhesus monkey: an electron microscopic study.
Primate fetal neostriatal neurons were implanted into the ibotenic acid-lesioned primate striatum and the animals were allowed to survive for 8 months. Light microscopic examination of the transplanted tissue demonstrated that the grafts were between 1.0 and 1.5 mm in diameter. The transplants were highly gliotic, but contained both normal appearing and degenerating neurons. At the electron microscopic level, the transplanted neurons displayed ultrastructural features identical to those of medium spiny, medium aspiny, and large aspiny striatal neurons. However, the majority of the grafted neurons showed evidence of degeneration. The grafts' neuropil demonstrated numerous glial processes, as well as mature axodendritic and axospinous synapses. Although this study was limited to only two graft recipients, the degenerative changes seen in the long-term primate allografts suggest that extension of these techniques into the clinical setting may be premature at the present time.
A method for utilizing biocytin to study retinofugal pathways at the light and electron microscopic levels.
Numerous methods have been utilized in the past to study the retinofugal pathway at both the light and electron microscopic levels. However, many of these techniques have technical drawbacks that make them difficult to use in electron microscopic studies. We present herein a method for utilizing the anterograde tracer biocytin to study the retinal pathways at both the light and electron microscopic levels. Biocytin is an especially useful tracer since it clearly labels very small axons and boutons in addition to the larger fibers. In addition, the synaptic ultrastructure is left intact and the technique can be utilized in numerous double-labeling neuroanatomical studies.
Imaging equipment for small hospitals.
Imaging equipment is expensive and the correct choice is difficult. Guidelines are provided. The proper choice will result in high quality x-rays and ultrasound scans even where electrical power is unreliable and no technical staff are available.
Choline acetyltransferase- and substance P-like immunoreactive elements in fetal striatal grafts in the rat: a correlated light and electron microscopic study.
Fetal striatal neurons were transplanted into the ibotenic acid-lesioned rat striatum. Three months after transplantation, the graft tissue was processed for choline acetyltransferase- and substance P-like immunoreactivity and was subsequently examined at the light and electron microscopic levels. The study demonstrated that choline acetyltransferase- and substance P-like-immunoreactive neurons were homogenously present throughout fetal striatal grafts, although in decreased numbers compared with those in the normal rat striatum. The majority of the choline acetyltransferase-immunoreactive neurons had fusiform, oval, or polygonal somata with somatic diameters greater than 20 microns and contained deeply invaginated nuclei surrounded by copious cytoplasm. In addition, choline acetyltransferase-immunoreactive neurons with somatic diameters between 10 and 20 microns were also demonstrated. The grafts' substance P-like-immunoreactive neurons, which had somatic diameters between 10 and 25 microns and had oval or polygonal perikarya, could be classified into two types based on their ultrastructural characteristics. Type I neurons contained an unindented nucleus which was surrounded by a thin rim or moderate amount of cytoplasm, whereas Type II immunoreactive neurons contained an indented nucleus which was surrounded by copious cytoplasm. Choline acetyltransferase- and substance P-like-immunoreactive dendrites in the grafts' neuropil were contacted by multiple unlabeled axon terminals. In addition, choline acetyltransferase- and substance P-like-immunoreactive axon terminals forming symmetric contacts with unlabeled dendrites were present within the graft. The study demonstrated that many of the neuroanatomical features of choline acetyltransferase- and substance P-like-immunoreactive elements found in the normal rat striatum are present in mature fetal striatal grafts.
Descriptive morphology of developing fetal neostriatal allografts in the rhesus monkey: a correlated light and electron microscopic Golgi study.
Primate fetal striatal neurons were transplanted into the ibotenic acid lesioned rhesus monkey striatum. Ten weeks after transplantation the monkeys were transcardially perfused and graft tissue was histologically stained. Golgi impregnated, and processed for electron microscopy. The monkeys received magnetic resonance imaging (MRI) scans before lesioning, after lesioning, and ten weeks after transplantation to noninvasively study the striatal grafts. The study demonstrated that fetal striatal grafts, measuring up to 0.4 x 0.8 cm, can survive for extended periods of time in the non-human primate. Hematoxylin-eosin stained sections of the transplant demonstrated that neuronal, glial, vascular, and lymphocytic cells were present in the graft. The majority of the neurons had somatic diameters between 8 and 20 microns and were characterized by nuclei containing multiple nucleoli. A few neurons within the graft had somatic diameters up to 40 microns. These larger neurons exhibited more mature cytoplasm containing a moderate amount of Nissl substance. Some of the blood vessels within the graft were surrounded by a large number of plasma cells, but there was no evidence of hemorrhage or necrosis. Bielschowsky staining and Golgi impregnation of the transplanted tissue demonstrated that there were neurons at various degrees of differentiation. Some of the neurons had varicose dendrites, growth cones, and filopodia, which are all characteristics of immature neurons, while others had a much more mature appearance, including a moderate number of dendritic spines. Some of these neurons had an appearance typical of differentiating "medium spiny" neurons of the normal striatum. Electron microscopic analysis of the transplanted tissue and individual Golgi-impregnated neurons within the transplant confirmed that there were developing neurons within the graft. These neurons had an increased nuclear-to-cytoplasmic ratio and had nuclei containing multiple nucleoli. The neuropil surrounding these neurons was loosely organized and contained large areas of extracellular space. The neuropil exhibited developing dendrites, numerous growth cones, and mature synapses. In summary, the study demonstrated that fetal striatal allografts can survive for up to three months in the rhesus monkey and undergo normal differentiation as assessed by Golgi impregnation and electron microscopy.
Feeling unwell? Must you go straight to hospital?
If people ignore the primary level and go directly to hospital when they are ill the health care system becomes overburdened at the higher levels, inefficient, and unjustifiably expensive. The most effective way to persuade people to use the first level of care is to ensure that its services are reliable and its facilities are attractive as those of the referral levels. Financial incentives aimed at encouraging respect for the system can also play a part.
Fetal neostriatal transplants in the rat: a light and electron microscopic Golgi study.
Fetal striatal neurons were transplanted into the ibotenic acid lesioned rat striatum. Three months after transplantation the grafted tissue was Golgi-impregnated and examined at the light microscopic level to determine the morphological characteristics of the transplanted neurons. Golgi-impregnated neurons were then gold-toned and examined at the electron microscopic level. The transplanted neurons were classified by both somatic size and somatic and dendritic morphology, which demonstrated that at least seven distinct cell types are present in striatal grafts. Type I large neurons had aspinous somata, sparsely spined dendrites, and indented nuclei, whereas type II large neurons displayed somatic spines, sparsely spined dendrites, and indented nuclei. Type I medium neurons exhibited aspinous somata and proximal dendrites, heavily spined distal dendrites, and unindented nuclei. Type II medium neurons had somatic spines, sparsely spined dendrites, and indented nuclei. Type III medium neurons had aspinous somata, poorly branched and sparsely spined dendrites, and indented nuclei, while type IV medium neurons had aspinous somata, highly branched and sparsely spined dendrites, and indented nuclei. Type V medium neurons displayed aspinous somata, varicose dendrites, and indented nuclei. These results demonstrate that transplanted fetal striatal neurons differentiate into morphologically and ultrastructurally distinct striatal cell types.
Prolactinoma in wall of ovarian dermoid cyst with hyperprolactinemia.
A 41-year-old woman with long-standing amenorrhea and hyperprolactinemia that disappeared after hysterectomy and bilateral salpingo-oophorectomy was found to have a prolactinoma in the wall of a dermoid cyst. Prolactin was demonstrated in the tumor cells by immunohistochemical staining.
Rational use of diagnostic imaging in paediatrics. The report of a World Health Organization Study Group.
The World Health Organization (WHO) is the agency of the United Nations with primary responsibility for international health matters and public health. Through the exchange of the knowledge and experience of health professionals from 165 nations WHO promotes comprehensive health services worldwide. As a part of this effort WHO has in recent years been concerned with improving the availability and utilization of diagnostic imaging, especially as it relates to health services in developing countries. Having devised and specified suitable basic radiographic equipment (the WHO BRS) a WHO Scientific Group was convened in 1982 to study the utilization of radiographic procedures and to to recommend their more efficacious and rational use. Then in 1984, recognizing the implications of newer imaging technology on world health, a second WHO Scientific Group considered the design, impact and future use of ultrasonography and computed tomography in developing countries. The findings of these scientific groups were published as part of the WHO Technical Report Series which makes available the recommendations of such international groups of experts. Although some of the needs of children were considered in these previous Technical Reports, WHO felt that the size and socioeconomic importance of the paediatric population worldwide warranted a further study and report to address the particular technical and clinical problems of diagnostic imaging in the paediatric age group. Thus a third WHO Scientific Group met in Geneva from 18 to 24 November 1985 to review established practices and experience in paediatric imaging throughout the world; and to recommend rational guidelines for diagnostic imaging for children to age 14 years.(ABSTRACT TRUNCATED AT 250 WORDS)