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Biomedical subjects

J C Folan

Publications and source records attributed to J C Folan.

10 recordsLinked to original sources
PubMed1990

Variations in atrioventricular valve innervation in four species of mammals.

In this series of studies, the innervation patterns of whole-mount preparations of bicuspid and tricuspid valves were studied by light microscopy in the mouse, rat, guinea pig, and opossum. The acetylcholinesterase-positive networks of nerve fibers showed many similarities in the basic patterns of valve innervation in all of the species studied, but several interspecies variations were observed. The basal zone of the valve adjacent to the fibromuscular atrioventricular ring displayed the most dense plexus of nerves, with acetylcholinesterase-positive fibers being seen across the width of the valve. In the intermediate zone of the valve, less dense plexuses of nerve fibers were found; and these were more numerous in the cuspal areas and less numerous in the intervening commissural areas. In the distal portions of the valve, nerve networks arborized extensively, with some of their nerve fibers extending toward the chordae tendineae and the free edges of the valve cusps. Only in the guinea pig and opossum did these fibers reach the free margin of the valve cusp, where they either ended directly as free nerve endings or lay parallel to the free edge of the cusp, often running between adjacent chordae tendineae. Although the patterns of innervation were similar in both bicuspid and tricuspid valves, the innervation density of the bicuspid valve was greater than that of the tricuspid valve for each species examined. A distinguishing feature of guinea pig and opossum tricuspid valves was that their chordae tendineae were relatively more prominent and more densely innervated than the bicuspid chordae tendineae. Free nerve endings with no light microscopic evidence of specialization were present throughout the bicuspid and tricuspid valves of all species studied. Some nerve endings in the opossum showed evidence of specialization, with brush-like arborizations leading to presumed free terminals seen chiefly in the distal zone of the valve cusps. Although some general tendencies were apparent, we have demonstrated that interspecies heterogeneity exists in the terminal networks of the atrioventricular valves of mouse, rat, guinea pig, and opossum.

Animals↗
PubMed1990

Paraganglionic cell response to chronic imipramine and handling stress: an ultrastructural study.

The ultrastructure and connectivity of monoamine-storing paraganglionic cells in the rat superior cervical ganglion were investigated following chronic treatment with imipramine (Tofranil, Ciba-Geigy) and compared with uninjected unhandled controls and saline injected animals. The study reveals a significant decrease in the number of dense core vesicles in the drug-treated group (P less than 0.001) which is regarded as a specific effect due to receptor blocking actions of imipramine. A significant reduction in the maximum diameter of the external rim and internal cores of the vesicles (P less than 0.05) in the drug-treated group is mimicked to a certain extent by saline injections, indicating a mixed effect of stress handling and specific alteration. Although the paraganglionic cell morphology is unaltered in the group comparisons, the interrelationship of the paraganglionic cells to surrounding neural processes is significantly altered in both the control versus saline and the control versus drug group comparisons (P less than 0.05). The drug- and saline-induced alterations of neural connectivity may reflect stress-induced general changes demonstrating the plasticity of the paraganglionic cell population.

Animals↗
PubMed1989

Effect of infection with the ts22 mutant of Semliki Forest virus on development of the central nervous system in the fetal mouse.

The A7 strain of Semliki Forest virus induces rapid fetal death in pregnant mice, whereas the ts22 mutant derived from it is teratogenic for a proportion of fetuses. Both A7 and ts22 induce viremia and infect the central nervous systems and fetuses of pregnant mice. Using immunogold-silver staining, a cDNA probe for a Semliki Forest virus nonstructural sequence, and a riboprobe derived from the same sequence, we showed that the skin and musculoskeletal systems of fetuses from mothers infected with ts22 were often heavily infected but the central nervous systems were not labeled before day 17 of pregnancy. Damage to the neural tube, including open-neural-tube defects, was detected in fetuses following infection of the mother at days 8 and 10 of pregnancy with both A7 and ts22. For ts22, neural tube damage induced by fetal infection before day 17 of pregnancy appeared to be indirect and caused by virus infection of mesenchymal cells surrounding the developing neural tube.

Animals↗
PubMed1988

Teratogenicity of the Semliki Forest virus mutant ts22 for the foetal mouse: induction of skeletal and skin defects.

The maximum proportion of skeletal and/or skin defects induced by the Semliki Forest virus (SFV) mutant ts22 in the 17-day-old foetal mouse occurred following infection of the mother at day 10 of pregnancy. The skeletal defects were detected using a combination of Alcian blue staining for cartilage and Alizarin red staining for bone. Using immunogold-silver staining with anti-SFV IgG and in situ hybridization with a cDNA probe to SFV non-structural sequences, we have shown that mesenchymal cells in the dermis and surrounding developing cartilaginous plates were heavily infected in most foetuses at day 17 of pregnancy, following infection of the mother at day 10. Other infected foetal tissues contained less viral antigen and nucleic acid; they included the liver, muscle (including myocardium), lung and kidney. The central nervous system contained only small amounts of viral antigen and nucleic acid. It is proposed that the skeletal and skin defects induced in mouse foetuses by ts22 infection result from the tropism of the virus for mesenchymal cells involved in the development of such tissue.

Animals↗
PubMed1986

Visual memory and auditory recall in anatomy students.

The performance of medical students in anatomy assessments of the spot, viva and essay type were compared with their performance in visual memory and auditory recall tests. The results demonstrate that defects in visual memory might be a contributory factor to poor performance in anatomy.

Anatomy↗
PubMed1985

Anti-tetanus immunisation in orienteers.

The present state of anti-tetanus immunisation amongst orienteering runners from 20 countries was assessed by questioning the orienteers as to when they last received an anti-tetanus injection. The results demonstrate that approximately 55% were within five years of their last injection, 18% were within 5-10 years, 12% were greater than 10 years and a further 15% did not know when or had never had an anti-tetanus injection.

Adolescent↗
PubMed1981

Peroneus longus tenosynovitis.

Tenosynovitis of the tendon of peroneus longus has rarely been described in the literature (Aberle-Horstenegg, 1932; Burman and Lapidus, 1931). This is a report on the condition in two athletes and in one of whom the os peroneum was absent on the side of the tenosynovitis. It emphasises the importance of a detailed review of athletes' training patterns when assessing their injuries.

Adult↗
PubMed1975

The innervation of hyperplastic epidermis in the mouse: a light microscopic study.

The innervation of the skin of hairless mice has been studied following induction of epidermal hyperplasia by physical and chemical methods. Physical stimuli comprised ultraviolet irradiation, heat, wounding, and friction. Effective chemicals included benzene, carbon tetrachloride, chloroform, creosote, formaldehyde, hexadecane, hydrobromic acid, sodium lauryl sulfate, and turpentine. Epidermal hyperplasia, however produced, was associated with growth of sensory nerve fibers into the outer part of the epidermis. Following a single 10-min exposure to an ultraviolet sunalmp at 40 cm, the nerves extended into the epidermis within 24 hr and disappeared during the second week as the epidermis reverted to its normal thickness. Repeated irradiation (until tumors appeared) was accompanied by persistent hyperplasia and neural invasion. Of 32 papillomas examined, intraepithelial nerves were found in 28. The presence and location of nerves in the tumor epithelium were related to the incorporation of tactile hair disc epithelium. The hyperplastic regenerative epithelium at the margins of skin ulcers were also invaded by nerves which sometimes followed the migrating epithelium across the ulcer floor. Since the regenerative epithelium was not directly treated, it was concluded that the proliferation of nervous tissue in response to skin injury was the result of the hyperplasia per se, regardless of the method used to produce it.

Acids↗
PubMedDate not supplied

Immunohistochemical evidence for different opioid systems in the rat superior cervical ganglion as revealed by imipramine treatment and receptor blockade.

The distribution pattern of opioid-immunoreactive nerve cell bodies and varicose fibres in the rat superior cervical ganglion after chronic administration of the tricyclic antidepressant imipramine, various receptor blockades (muscarinic antagonist, atropine sulphate; opiate antagonist, naloxone; kappa-antagonist, MR2266BS), and denervation was investigated immunohistochemically using a biotin-streptavidin-peroxydase complex method. Antisera to four peptides derived from two different precursors of the opioid family were used. In control superior cervical ganglia sparsely scattered nerve fibres and no neuronal cell bodies were immunoreactive when antisera to dynorphin A (1-17) or alpha-neo-endorphin (cleavage products of prodynorphin) were applied. A moderate number of nerve fibres and neuronal perikarya were immunoreactive to antisera directed against met-enkephalin-arg-phe (cleavage product of proenkephalin) and leu-enkephalin (cleavage product of prodynorphin and proenkephalin); non-identical cell bodies contained met-enkephalin-arg-phe- or leu-enkephalin-immunoreactivity. After drug treatment specific changes in the immunoreactivity of the investigated peptides in the superior cervical ganglion were demonstrated. (a) Treatment with imipramine resulted in an increase of nerve fibres demonstrating immunoreactivity to antisera against dynorphin A and alpha-neoendorphin. In contrast, no alteration in the numbers of nerve fibers but a numerical increase of postganglionic cell bodies immunoreactive to either met-enkephalin-arg-phe or leu-enkephalin antisera was demonstrated. Moreover, some perikarya exhibited immunoreactivity to both these opioids. (b) Receptor blockade with the muscarinic antagonist atropine sulphate or the general opiate antagonist naloxone had no effect on the number and distribution of dynorphin A or alpha-neoendorphin immunoreactive fibres, whereas both met-enkephalin-arg-phe and leu-enkephalin-immunoreactive fibres and postganglionic perikarya were increased in number. (c) After the kappa antagonist (MR2266BS), an increase of fibres with prodynorphin-derived opioid immunoreactivity as well as those with met-enkephalin-arg-phe- or leu-enkephalin-immunolabelling was visible and the met-enkephalin-arg-phe and leu-enkephalin-immunoreactive cell bodies were increased in number. The preganglionic origin of the investigated fibres with prodynorphin cleavage products was concluded from the complete disappearance of such fibres after preganglionic denervation. Denervation also resulted in an increase of met-enkephalin-arg-phe- and leu-enkephalin-immunoreactive perikarya. Small intensely fluorescent (SIF) cells, which in controls were nonrea

Amino Acid Sequence↗