PubMed Health⌕ Search

Biomedical subjects

David R Kelly

Publications and source records attributed to David R Kelly.

At least 19 recordsLinked to original sources
PubMed2007

The tectorial membrane: anatomical, biomechanical, and histological analysis.

There is minimal information in the literature regarding the tectorial membrane. Further, information in the literature regarding the anatomy and function of this structure is often contradictory. We performed the current study to elucidate further this structure's detailed anatomy, function, and histology. Thirteen adult cadavers underwent dissection of their tectorial membranes and detailed observations and measurements were made of them. Ranges of motion of the craniocervical junction were performed before and after transection of this structure. Histological analysis was performed on all membranes. The tectorial membrane was found to attach much more superiorly than previously described and was found to be firmly adherent to the cranial base and body of the axis but not to the posterior aspect of the odontoid process. The mean thickness of this membrane was found to be 1 mm. Flexion of the head made the tectorial membrane fully taut at 15 degrees and extension made it fully taut at 20 degrees; however, there was a buckling effect (redundant tectorial membrane) noted at the level of the odontoid process in extension. With the alar and transverse ligaments cut and with flexion of the head, the middle portion of this membrane was stretched over the odontoid process, thus acting as a "hammock" that inhibited the odontoid process from moving posteriorly. The tectorial membrane did not limit cervical flexion per se but rather helped to insure that the odontoid process did not impinge into the cervical canal. Lateral flexion was not found to be limited by this structure. Histologically, parallel collagen fibers with spindle-shaped fibrocytes were observed within this membrane and near its attachment to the posterior axis, the collagen fibers were noted to be more homogenous with larger non-spindled fibrocytes. At the cranial attachment of the tectorial membrane, multiple calcified areas were noted that interdigitated with the underlying bone. Also near this cephalic bony attachment, there was an increase in the number of elastic fibers, which were found running parallel with the surrounding Type III collagen fibers. The tectorial membrane was found to attach much more superiorly than previously described. We would propose that the tectorial membrane provides for a second line of defense, preventing the odontoid process from compressing the spinal cord and by doing so, secondarily limits movement of the craniocervical juncture. This hypothesis is strengthened by the finding of many elastic fibers in the tectorial membrane. To our knowledge, our study is the first to perform a detailed histological analysis of the tectorial membrane. We hope that these data are useful to the clinician who investigates this ligament of the craniocervical region.

Aged↗
PubMed2007

Benign fibrous histiocytoma of the skull base. Case report.

The authors report the case of benign fibrous histiocytoma (BFH) of the skull base in an 11-month-old girl. During draining for a middle ear infection, the child was noted to have an anomalous mass in the skull base. On magnetic resonance imaging studies a soft-tissue mass of the skull base primarily involving the regions of the temporal and occipital bones was discovered. Results of a surgical biopsy were consistent with BFH. At the most recent follow-up examination--18 months postoperatively--the child was noted to be asymptomatic with no gross increase in tumor size.

Biomarkers, Tumor↗
PubMed2006

FGF-10 is decreased in bronchopulmonary dysplasia and suppressed by Toll-like receptor activation.

Many extremely preterm infants continue to suffer from bronchopulmonary dysplasia, which results from abnormal saccular-stage lung development. Here, we show that fibroblast growth factor-10 (FGF-10) is required for saccular lung development and reduced in the lung tissue of infants with bronchopulmonary dysplasia. Although exposure to bacteria increases the risk of bronchopulmonary dysplasia, no molecular target has been identified connecting inflammatory stimuli and abnormal lung development. In an experimental mouse model of saccular lung development, activation of Toll-like receptor 2 (TLR2) or Toll-like receptor 4 (TLR4) inhibited FGF-10 expression, leading to abnormal saccular airway morphogenesis. In addition, Toll-mediated FGF-10 inhibition disrupted the normal positioning of myofibroblasts around saccular airways, similar to the mislocalization of myofibroblasts seen in patients with bronchopulmonary dysplasia. Reduced FGF-10 expression may therefore link the innate immune system and impaired lung development in bronchopulmonary dysplasia.

Animals↗
PubMed2006

Oligopeptides as catalysts for asymmetric epoxidation.

Oligopeptides are versatile catalysts for the enantioselective epoxidation of electron deficient alkenes, (e.g. alpha,beta-unsaturated ketones) with alkaline hydrogen peroxide. This review describes optimisation of the catalyst, substrate range, synthetic applications of the products and rationalisation of the stereoselectivity by an active site model.

Alkenes↗
PubMed2006

Complete ossification of the human falx cerebri.

During the routine dissection of the head and neck of an adult male cadaver complete ossification of the falx cerebri was noted. Anomalous ossification was not found in any other dural component or other parts of the body. The brain appeared grossly normal. Histological sections showed normal ossification processes involving the falx cerebri. In addition, rare scattered deposits of metastatic poorly differentiated carcinoma within the trabecular spaces were seen. Reports of isolated islands of ossification involving primarily the most anterior part of the falx cerebri in man are found in the literature. Our case report represents to our knowledge, the first report of complete ossification of this dural partition. Whether this is simply an anomalous configuration or due to the few metastatic cells found within this region remains unclear.

Aged↗
PubMed2006

Pseudorheumatoid nodule in the liver of an adolescent male.

Focal hepatic lesions in the pediatric population are rare and are usually found on incidental imaging of the abdomen. The most common lesions are focal nodular hyperplasia and hemangioma, but the differential diagnosis is quite broad. We present a case of an adolescent male who was found to have a large pseudorheumatoid nodule of the liver that was successfully resected. Only one previous case is reported in the literature and none in the pediatric age group.

Adolescent↗
PubMed2006

Does the ganglion of Ribes exist?

Some have included the ganglion of Ribes (Francois Ribes, 1765-1845), lying on the anterior communicating artery, as the most superior ganglion of the sympathetic nervous system. To verify the presence of this structure, the anterior communicating artery was harvested from 40 fresh adult cadavers and histological analysis and immunochemistry performed. Grossly and with magnification, no ganglion-like structures were found in or around the anterior communicating artery in any specimen. However, scattered neuronal cell bodies were found in the adventitia of the anterior communicating artery with histological immunochemical analysis. Based on the lack of vasoactive intestinal peptide staining and the positive reaction to tyrosine hydroxylase, these neurons are most likely sympathetic in nature. Based on our findings, a grossly visible ganglion of Ribes does not exist. However, neuronal cell bodies were found in the adventitia of the anterior communicating artery although the function of such cells remains speculative.

Aged↗
PubMed2005

Occult spinal dysraphism and Pacinian hamartomas.

CASES: The authors report two patients with occult spinal dysraphism who, following histological analysis, were found to harbor associated Pacinian hamartomas. One patient's hamartoma was found in conjunction with their lipomyelomeningocele and the other was combined with a presacral myxopapillary ependymoma associated with a fatty filum terminale. DISCUSSION AND CONCLUSION: We review the literature and believe this to be only the third report of Pacinian hamartomas in association with occult spinal dysraphism. Although Pacinian hamartomas are seemingly rare in conjunction with occult spinal dysraphism, mesodermal elements are often found in this disease entity.

Hamartoma↗
PubMed2005

Spinal cord compression as a result of Rosai-Dorfman disease of the upper cervical spine in a child.

BACKGROUND: Rosai-Dorfman disease is characterized by massive painless cervical lymphadenopathy, but can also include nasal obstruction, tonsillar enlargement, or hearing abnormalities. The disease occurs most often in the third and fourth decades. Most authors have suggested that it represents either an autoimmune disease or a reaction to an infectious agent that has yet to be discovered. Less than 50 cases of central nervous system involvement have been reported. CASE ILLUSTRATION: We report a child with cervical spinal cord compression due to Rosai-Dorfman disease of the cervical spine. PROGNOSIS: This disease has variable outcomes from relatively benign to insidious over decades. Our case is unusual in that the patient was a child and had involvement of the spine with resultant cord compression, a combination that has been reported rarely.

Adolescent↗
PubMed2005

Aneurysm of the distal facial artery from a penetrating oral prosthesis.

We report a 94-year-old male who died of pneumonia. During the routine dissection of the head and neck for a gross anatomy course at our institution a mass was noted in the region of the right cheek. Macroscopic and microscopic observation of this mass revealed an aneurysm of the facial artery. A traumatic defect was noted at the apex of the aneurysmal wall related to an intraoral prosthetic clasp that had penetrated the buccinator muscle. Traumatic aneurysms of the face have been caused by blunt trauma to the jaw with or without fracture, surgical manipulation around the teeth and jaw, and following missile injury. Some have described compression of neighboring structures such as cranial nerves and other blood vessels with resultant compromise. We believe our case to be the first report of a facial artery aneurysm in a cadaver and we are unaware of other reports from the literature describing the production of a facial artery aneurysm from a puncture of an intraoral prosthesis through the medially placed buccinator muscle. Although seemingly rare, health care professionals should make efforts to ensure that oral prostheses do not develop sharp or irregular edges that could potentially perforate the lateral oral cavity with potential perforation of the overlying vasculature.

Aged, 80 and over↗
PubMed2005

Polyamino acids as synthetic enzymes: mechanism, applications and relevance to prebiotic catalysis.

Polyamino acids, such as polyleucine, behave as synthetic enzymes in the asymmetric epoxidation of chalcone and other electron-deficient alkenes (the Julià-Colonna reaction). The influences of reaction conditions, of the molecular structure of the catalysts and of the scaling-up of the process on the enantioselectivity of the reaction have been determined. The kinetics and mechanism have been investigated using a soluble PEG-polyleucine conjugate, which behaves in a similar way to an enzyme, showing saturation kinetics for both chalcone and HOO-. Enantioselective catalysis is achieved with peptides with as few as five residues and scalemic catalysts show high chiral amplification. Here, we discuss the relevance of these-enzyme like catalysts to prebiotic processes, such as the role of small peptides in the formation of optically active cyanohydrins.

Amino Acids↗
PubMed2005

The filum terminale externum.

OBJECT: The filum terminale externum (FTE) is the extradural component of the filum terminale internum and little attention has been dedicated to this structure in the literature. The authors theorized that the rare intrasacral ependymomas may originate from ependymal cell collections within the FTE. METHODS: To address this hypothesis, the FTE was dissected and analyzed histologically in 15 adult cadavers. None of the specimens was found to harbor ependymal or other glial cell collections. CONCLUSIONS: The authors found previously undescribed smooth-muscle cells within the FTE. Furthermore, histological analysis identified adipose, nerve, bone, and cartilage cells.

Adipose Tissue↗
PubMed2004

The preference for anti over Gauche migration in the Baeyer-Villiger reaction.

Explanations for stereoselectivity in the Baeyer-Villiger reaction have relied on the assumption that the antiperiplanar (app) group migrates. However, the magnitude of the preference for app-migration over gauche migration is unknown. To investigate this, the energy differences between the two were estimated from ab initio calculations. App-migration was found to be the preferred pathway since no transition structure could be located for gauche migration. Barriers for gauche migration were estimated by performing constrained optimizations. App-migration was found to be strongly favored with a barrier that is at least 3.8 kcal/mol and as much as 58.0 kcal/mol lower in energy than the gauche migration barrier.

Cyclization↗
PubMed2004

The mechanism of polyleucine catalysed asymmetric epoxidation.

Catalysis in the Julia-Colonna epoxidation of alpha,beta-unsaturated ketones is due to binding of the hydroperoxide enolate intermediate by the three N-terminal amidic N-H groups of alpha-helical poly-leucine; the N-terminal pair forms an oxy-anion hole, whilst the third aids displacement of hydroxide.

Catalysis↗
PubMed2004

Splenogonadal fusion diagnosed by Doppler ultrasonography.

Splenogonadal fusion usually presents as a left scrotal mass but rarely is the diagnosis suspected preoperatively. Herein, we present the first report of a left splenogonadal fusion which was suspected preoperatively by doppler ultrasonography in a 2 year old boy.

Abnormalities, Multiple↗
PubMed2003

Choristomatous polyps of the aural and pharyngeal regions: first simultaneous case.

The first known case of embryological development of a salivary gland choristoma of the middle ear and a hairy teratoid (choristomatous) mass of the pharynx arising in the same patient is reported. On the day after the patient, a female, was born, a posterior pharyngeal mass was discovered, resected, and diagnosed histopathologically as a hairy teratoid (choristomatous) polyp. At 10 months of age, the patient underwent myringotomy and tympanostomy tube placement, and another mass was found in the left middle ear. This mass was diagnosed as a salivary gland choristoma. Our review of the literature showed that, consistent with our case, choristomas are more prevalent in females, and those in the middle ear almost always occur on the left side. Both types of polyps are rare and are thought to be due to errors in development of the second and first branchial arches.

Biopsy, Needle↗