Biomedical subjects
M Ramer
Publications and source records attributed to M Ramer.
Reduced sympathetic sprouting occurs in dorsal root ganglia after axotomy in mice lacking low-affinity neurotrophin receptor.
Following sciatic nerve injury, sympathetic axons sprout into the L5 dorsal root ganglion (DRG). The low-affinity neurotrophin receptor (p75) is strongly expressed by glial cells in DRG following axotomy. We tested the hypothesis that p75 is involved in this sympathetic sprouting by comparing sprouting following sciatic nerve cut in wild-type (CD1) and p75 knockout mice. Twenty-one days after injury sympathetic sprouting had occurred in both mouse strains, though the extent of sprouting (measured as length of sprouts per unit area of DRG) was less in p75 knockout mice. We conclude that p75 expression enhances, but is not required for, sympathetic sprouting.
Biomechanical validation of a new nail-plate for the repair of stable proximal femoral fractures.
The mechanical performance and the stress shielding effects of the Howmedica Spherolock MKII implant were evaluated. Three types of stable proximal femoral fractures were created in composite femurs and fixed with the nail-plate. The femurs were loaded to failure, and the yield strength, stiffness, and failure modes were noted. Additional intact composite femurs were fitted proximally with strain gauges, and the strain was examined under load. The femurs then underwent intertrochanteric fracture, plating, and re-testing. Comparative analysis showed that while the Spherolock system is less strong and stiff than other commonly used implants, it provides excellent and uniform load transfer across the fracture site. Varus rotation of the femoral head under load tended to open the fracture gap and localize the resultant load medially. Stress shielding of the calcar was less than 25% of the applied load even in the worst case. This very low stress shielding behavior was attributed mainly to the implant's low stiffness.
Keratoameloblastoma of the maxilla. A case report and review of the literature.
The keratoameloblastoma is a rare histologic variant of the ameloblastoma. Review of the English language literature revealed five case reports of keratoameloblastoma. We report the sixth case of this tumor. The tumor developed in the right posterior maxilla of a 26-year-old African-American man and demonstrated aggressive clinical behavior, analogous to conventional ameloblastoma. The initial biopsy specimen showed extensive cyst formation, which histologically resembled odontogenic keratocyst. However, the lining epithelium varied in thickness and there was separation and edema between the basal cells and the rest of the epithelium. The basal cells were strongly adherent to the underlying stroma unlike the basal layer of the odontogenic keratocyst, where cleavage often occurs in this area. Additionally, although the basal cells were palisaded and demonstrated nuclear polarization in areas, they were cuboidal rather than columnar. The excision specimen revealed more of a solid ameloblastic component in addition to the cystic component seen on the initial biopsy. Nevertheless, it is possible that the ameloblastoma had developed in an odontogenic keratocyst. Alternatively, it can be postulated that the keratoameloblastoma consists of both cystic and solid components, the former being analogous to the cysts of the conventional ameloblastoma.
Glandular odontogenic cyst: report of a case and review of the literature.
The glandular odontogenic cyst is a rare jawbone cyst of odontogenic origin, first described in 1988 by Gardner et al. We describe a previously unreported case of a combined cyst composed of glandular odontogenic cyst and ghost cell keratinization that was present for 33 years. We also reviewed the published 38 cases of glandular odontogenic cyst found in the world literature and add this additional case.
Childhood hypophosphatasia. A case report.
Hypophosphatasia is a hereditary disease that can present as premature exfoliation of deciduous dentition in young children. We present a case of a 32-month-old female with a history of skeletal problems who spontaneously exfoliated three mandibular primary teeth. It was the premature exfoliation of her mandibular teeth that led to the diagnosis of childhood hypophosphatasia.
Smoker's melanosis. Report of a case.
Melanin pigmentation of the oral cavity among tobacco smokers, "smoker's melanosis", was first described by Hedin in 1977. Studies performed on dark skinned ethnic groups found that although nearly all non-tobacco users had oral melanin pigmentation; tobacco smokers had significantly more oral surfaces pigmented than non-tobacco users. We present a case of oral smokers melanosis involving the tongue of a 37-year-old black female.
Hereditary gingival fibromatosis: identification, treatment, control.
Hereditary gingival fibromatosis, or HGF, is characterized by varying degrees of attached gingival hyperplasia. The authors describe a case of generalized severe hereditary gingival fibromatosis involving the maxillary and mandibular arches. Removal of excess gingival tissue by conventional gingivectomy dramatically improved the patient's appearance.
Epstein-Barr virus reactivation in hairy leukoplakia.
Hairy leukoplakia, often seen in patients with acquired immunodeficiency syndrome, is strongly associated with Epstein-Barr virus (EBV) infection and questionably associated with human papillomavirus (HPV) infection. To date, most in situ hybridization (ISH) studies suggest that the EBV is localized only to the superficial squamous layers, favoring the theory of lingual infection by saliva rather than by reactivation of latent lingual infection. We describe 11 formalin-fixed, paraffin-embedded specimens from patients with lingual hairy leukoplakia that we examined for the presence of the EBV, HPV, cytomegalovirus, and human immunodeficiency virus. We used standard DNA ISH for the EBV and cytomegalovirus and polymerase chain reaction ISH for the EBV, HPV, and human immunodeficiency virus. The EBV was present in all 11 specimens according to polymerase chain reaction ISH studies but in only seven specimens according to conventional DNA ISH. Polymerase chain reaction ISH localized the EBV to the basal and parabasal layers in addition to the strong localization in the upper epithelial layers. No evidence for HPV or cytomegalovirus DNA was found. The human immunodeficiency virus was focally localized to rare superficial squamous cells in seven specimens. The presence of EBV DNA in basal and parabasal lingual cells, as well as localization of latency-associated proteins in these layers, suggests that hairy leukoplakia in patients with acquired immunodeficiency syndrome might represent a reactivation of latent lingual infection accompanied by a dramatic increase in viral copy number in the more mature, superficial, squamous cells. The human immunodeficiency virus was also found in seven specimens, but the significance of this new finding is uncertain and requires further study. There is no evidence to suggest that the HPV is involved in the development of hairy leukoplakia.
Intrasplenic pancreatic pseudocyst: another cause of splenomegaly.
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Angiography in leiomyomatous neoplasms of the small bowel.
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