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D J Gower

Publications and source records attributed to D J Gower.

At least 19 recordsLinked to original sources
PubMed2001

Possible postcranial pneumaticity in the last common ancestor of birds and crocodilians: evidence from Erythrosuchus and other Mesozoic archosaurs.

Birds and crocodilians (extant archosaurs) have differing, distinctive morphologies. Birds have respiratory airsacs with diverticula that pneumatize the postcranial skeleton, a feature absent in crocodilians. Bony correlates of pneumatic sinuses are known in the vertebrae of some non-avian dinosaurs and in pterosaurs--taxa more closely related to birds than crocodilians. This and the apparent absence of pneumatic postcranial bones in fossil archosaurs more closely related to crocodilians than to birds, has been interpreted as evidence that postcranial pneumaticity is a derived character of birds and their nearest fossil relatives. The presence of apparent osteological correlates of postcranial pneumaticity is here reported in some non-crown-group archosaurs, and some of the fossil taxa more closely related to crocodilians than to birds. This suggests that the last common ancestor of birds and crocodilians might have had a pneumatized postcranium, and that the absence of this feature in crocodilians might be derived.

Alligators and Crocodiles↗
PubMed1994

Pediatric syringomyelia.

Syringomyelia was first recognized as a disease process some 400 years ago. The process of cystic dilation of the spinal cord is unpredictable and may result in a delay of many decades before the symptoms and signs of neurologic and orthopedic changes become apparent and commensurate with the observed cystic changes within the spinal cord. The syringomyelic process is usually associated with trauma, tumor, or congenital abnormalities at the craniocervical junction or along the spinal neuraxis. Several theories have been proposed as to processes involved in the development of spinal cyst formation, although none are completely compatible with the observed clinical pathology of syrinx development. Magnetic resonance imaging has markedly improved our ability to study the anatomy and natural history of syrinx formation, but to date, our understanding of the process remains imprecise. In view of the limited understanding of the pathophysiology of this disease process, it is not surprising that a variety of treatment regimens have been proposed and their efficacy remains difficult to fully evaluate.

Brain Diseases↗
PubMed1994

Thoracic intraspinal lipoma.

Intraspinal lipomas are rare congenital tumours that most commonly occur at the conus. We describe a thoracic intraspinal lipoma presenting with a myelopathy and imaged by MRI. Surgical decompression and dural enlargement appears to be the treatment of choice in those patients who develop spinal cord dysfunction associated with an intraspinal lipoma.

Adult↗
PubMed1992

Enlarging endostoma (bone island) of the spinous process.

Endostoma of bone (bone island) is a rare lesion and has been described in the spinous process in only one previous publication. Although these lesions are benign, they have a potential for enlargement. Radiography cannot completely differentiate these lesions from more aggressive processes, and removal of the lesion should be considered.

Adrenal Cortex Hormones↗
PubMed1992

e-PTFE ventricular shunt catheters.

The perfect polymer surface for implantation should resist the adhesion of bacteria while producing no reaction in surrounding tissues. Silicone elastomer is a common material used for medical implantation devices. This material is superior to most available for implantation because of its flexibility and low, but detectable, tissue reaction. We have evaluated a flexible, expanded polytetrafluoroethylene (e-PTFE) ventricular catheter for cerebrospinal fluid shunting and have found that although e-PTFE is safe for cerebral implantation, the porosity of the material allows tissue ingrowth that obstructs the lumen. Our limited clinical evaluation of 5-microns internodal distance e-PTFE revealed that this open-cell structure, allowing tissue ingrowth, apparently is a poor candidate to replace silicone elastomer in cerebrospinal fluid shunting devices. However, further investigation may provide a polymer superior to silicone elastomer to create a cerebrospinal fluid shunt.

Animals↗
PubMed1991

The rear-view halo.

Explore the source record for details and available documents.

Cervical Vertebrae↗
PubMed1990

Water deprivation protects photoreceptors against light damage.

Photoreceptor cell death after light-damage and during aging in rats is associated with the hormonal status of the animal, as well as other environmental and intrinsic factors. Restricted caloric intake extends the life of rodents and is usually accompanied by a reduction in water consumption. In this study, male and female rats were placed on restricted water intake for either 3 or 7 days to induce dehydration. Following exposure to damaging visible light, the retinas were evaluated for severity of damage and photoreceptor survival, heat shock (stress) protein (HSP) and total protein synthesis, and plasma arginine vasopressin (AVP) levels. Photoreceptor cells of 7-day, dehydrated male and female rats survived light-damage significantly better than those allowed water ad libitum; however, after 3 days of water restriction, only the male rats demonstrated protection from photodamage. Severity of photoreceptor damage could not be correlated with retinal HSP synthesis and content, although the latter was significantly reduced in dehydrated animals. Total retinal protein content and synthesis were unchanged by restricted water intake. AVP increased by 350% during the 7-day period of dehydration. Protection of photoreceptors from light-damage in this study may be correlated with osmotically stimulated changes in the retinas of dehydrated animals.

Aging↗
PubMed1990

Cystic optic glioma.

A pilocytic astrocytoma of the optic nerve, chiasm, hypothalamus, or third ventricle is a relatively common tumor of childhood. This case report illustrates such a tumor, originating from this location, which is unusual because of the association with two very large cystic extensions into the middle cranial fossa and into the third ventricle. The massive size and extent of this tumor and cysts was demonstrated on a magnetic resonance imaging (MRI) scan, with gadolinium enhancement. This case illustrates a novel macroscopic appearance for a pilocytic glioma of the anterior third ventricle. The purpose of this report is to alert clinicians to the varied morphology this tumor may present as we apply increasingly our improved radiological, operative, and histopathological techniques.

Astrocytoma↗
PubMed1990

Changing concepts in spinal epidural abscess: a report of 29 cases.

A review of our recent experience with spinal epidural abscess (SEA) reveals several important changing concepts in diagnosis, etiology, management, and outcome. All cases of SEA seen by our service from August 1975 to July 1989 were reviewed retrospectively, and 29 patients were identified (19 men and 10 women, aged 13-78 years). Abscesses were located in the lumbar (n = 21), thoracic (n = 7), and cervical (n = 1) epidural spaces. Gram-positive organisms were the infectious agent in 72% of the cases, and Staphylococcus aureus was the sole agent in 45%; other agents were Gram-negative aerobes (n = 5), a Gram-negative anaerobe (n = 1), Mycobacterium tuberculosis (n = 1), and Sporotrichum schenckii (n = 1), the last occurring in a young woman with acquired immune deficiency syndrome. Seventeen patients had concomitant extraspinal infections. Diagnosis was confirmed by myelography, computed tomography, or magnetic resonance imaging. All patients underwent operative decompression and debridement; 2 required a second procedure for persistent infection. The most common operative findings were pus and granulation tissue in the epidural space (52%); the preoperative course correlated poorly with operative findings. The wound was closed primarily in 84% of cases. Postoperative intravenous antibiotic courses for the bacterial abscesses ranged from 1.5 to 6 weeks (median, 2 weeks), followed by antibiotics given orally for 0 to 6 weeks. Two patients died perioperatively. Neurological outcome was good in 21 patients and fair in 6 (mean follow-up, 1.4 years). Over the last 50 years the spectrum of organisms causing SEA has broadened, and the distinction between acute and chronic SEAs has minimal clinical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Abscess↗
PubMed1990

Shunt-related brain abscess and ascending shunt infection.

We report the fifth case of shunt-related brain abscess. Two prior cases have been associated with colonic perforation and infection with gram-negative enteric organisms. These cases strongly suggest that ascending shunt infection is possible despite bulk cerebrospinal fluid flow in the opposite direction and add to our understanding of shunt infections.

Brain Abscess↗
PubMed1989

Surgical repair of aneurysms of the posterior inferior cerebellar artery--a clinical series.

Aneurysms of the posterior inferior cerebellar artery are relatively rare. Fourteen such aneurysms (10 vertebral, 4 peripheral) are reported, and their clinical presentation, surgical therapy, and outcome are discussed. All 14 patients had suffered a subarachnoid hemorrhage; 93% (n = 13) underwent direct clipping of the aneurysm while 7% (n = 1) underwent coating of the aneurysm. Two patients died in the perioperative period (one from vasospasm and one from rebleeding). Full activity was achieved by all but one (92%) of the remaining patients in extended follow-up.

Adult↗
PubMed1989

Spinal cord injury and the stress protein response.

The heat shock or stress response is a highly conserved primary cellular response to injury. Synthesis of stress proteins (also called "heat shock proteins") is an integral component of this response. Protection from various forms of sublethal stress following increased production of stress proteins has been demonstrated in a number of systems, including the retina. This immunocytochemical study demonstrates the synthesis, accumulation, and redistribution of the 70-kD stress protein following spinal cord injury in rats. The observations confirm that stress protein production is a fundamental feature of the molecular response of the spinal cord to injury, and raise the possibility that augmentation of this response could enhance posttraumatic neuronal survival.

Animals↗
PubMed1989

Image guided stereotaxic surgery.

Computerized tomographic (CT) scanning and magnetic resonance imaging (MRI) can demonstrate areas of abnormal tissue within the brain, sometimes smaller than can be safely found and biopsied by open surgery or free-hand needle techniques. Image guided stereotaxic surgery can accurately and reproducibly place a needle in the brain based upon data from high resolution images. Tissue biopsy, abscess or cyst drainage, placement of radioactive seeds, or removal of a parenchymal hematoma can be done with less patient morbidity and in-hospital time.

Brain Neoplasms↗
PubMed1988

Hyperthermia protects against light damage in the rat retina.

An increase in the synthesis of heat shock proteins that is induced in cells in vitro by hyperthermia or other types of metabolic stress correlates with enhanced cell survival upon further stress. To determine if a similar increase in stress tolerance could be elicited in vivo, rats were made hyperthermic, and then their retinas were tested for sensitivity to light damage. This treatment resulted in a marked decrease in photoreceptor degeneration after exposure to bright light as compared to normothermic animals. Concomitant with such protection was an increase in retinal synthesis of three heat shock proteins. Thus, a physiological rise in body temperature enhances the stress tolerance of nerve tissue, perhaps by increasing heat shock protein production.

Animals↗