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Biomedical subjects

H E James

Publications and source records attributed to H E James.

At least 55 records · Page 3Linked to original sources
PubMed1987

Experimental carbon dioxide laser brain lesions and intracranial dynamics: Part 3. Effect on cerebral blood flow.

Experimental carbon dioxide brain lesions were created over the intact dura mater of the left parietooccipital region of the anesthetized albino rabbit (40-watt impacts of 0.5-second duration, for a total of 4 seconds, with 0.5-second intervals between impacts), and cerebral blood flow (CBF) studies were performed with the hydrogen clearance technique. The animals were mechanically ventilated to maintain a constant PaCO2. Blood pressure, central venous pressure, electroencephalogram, and intracranial pressure were continuously monitored. The control CBF before lesion was 64.1 +/- 15.8 and 70.9 +/- 13.4 ml/100 g/minute for the left and the right hemispheres, respectively. CBF studies at 2, 4, 6, 8, and 24 hours after the lesion did not significantly change from the control values, save for a trend to increase over the right hemisphere only at 2 hours (range 106.0 +/- 55.4 to 41.6 +/- 9.3). It is concluded that in this model the changes in intracranial pressure and brain edema that are seen and have been previously reported are not due to change in cerebral circulation. The brain edema that results probably has characteristics similar to those seen in the cryogenic lesion (vasogenic) model, and this could account for the rise in intracranial pressure.

Animals↗
PubMed1986

The effect of carbon dioxide laser irradiation on cranial bone healing. An experimental study.

An experimental study on the effects of carbon dioxide laser irradiation osteotomy of the calvarium of 4-week old rabbits was compared with tht of an osteotomy performed with a high speed drill. Histological studies of calvarium cross sections were performed at 2, 4 and 6 weeks following the osteotomies. As early as 2 weeks following high speed drill osteotomy connective tissue bridged the bone edges. By 4 weeks this bridge was thickened and endowed with numerous vessels. At 6 weeks numerous osteoblasts lined the bone edge and connective tissue bridge. Following laser osteotomy the carbonized edges interrupted the connective tissue from bridging the bone edges at 2, 4 and 6 weeks. By 6 weeks following the laser osteotomy connective tissue had grown past the carbonized residue and the healing process proceeded with osteoblast proliferation from points beyond the carbonized residue. The significance of these findings in reference to the reossification process following osteotomies for craniosynostosis and craniofacial surgery, is discussed.

Animals↗
PubMed1986

The effects of acute high dose fentanyl administration on experimental brain edema: analysis of intracranial pressure, systemic arterial pressure, central venous pressure and brain water content.

In rabbits who had brain edema and intracranial hypertension induced by a combined cold lesion (over the left hemisphere) and a metabolic blocker (6-aminonicotinamide), the authors analyzed the response of multiple parameters following the administration of 6 mcg/kg/dose of fentanyl every 5 minutes for 1 hour (12 doses), combined with nitrous oxide anesthesia. All animals were mechanically ventilated and the PaCO2 was maintained at 37-43 torr. Gross pathology and extent of Evans Blue extravasation was no different from pretreatment control animals. The systolic arterial pressure and the central venous pressure showed no change during the experiment. The intracranial pressure remained elevated despite fentanyl, but did not increase or decrease throughout the administration of the agent. The brain water content remained unchanged in the right hemisphere, but revealed a significant increase following fentanyl in the cold-lesioned left hemisphere for the gray (p less than 0.005) and white matter (p less than 0.05).

Animals↗
PubMed1986

An experimental study on the effects of DMSO and indomethacin on cerebral circulation and intracranial pressure.

Albino rabbits with a cryogenic lesion to the left parieto-occipital cortex had cerebral blood flow studies (CBF) with the hydrogen clearance technique 24 hours after the insult. Similar subgroups were treated with DMSO (1 g/kg) bolus, DMSO (2 g/kg) infusion, indomethacin (20 mg/kg) bolus, and indomethacin followed by DMSO. Following DMSO bolus administration there was an immediate rise in CBF over both hemispheres, with a significant paradoxical decrease at 30 minutes, followed by a second smaller rise at 60 minutes. With DMSO infusion, the rise in CBF was sustained throughout the infusion period with no paradoxical decrease. With indomethacin there was an initial decrease immediately following the drug, and at 60 minutes there was a rise in the insulted left hemisphere, more than the right one. Indomethacin administration 15 minutes prior to DMSO failed to halt the immediate increase in CBF noted following DMSO bolus injection. These results, together with the changes that occurred in intracranial pressure and brain water content, are analyzed.

Animals↗
PubMed1986

Ventriculoperitoneal shunts in low birth weight infants with intracranial hemorrhage: neurodevelopmental outcome.

Fifty preterm infants (mean birth weight, 1266 +/- 303 g; mean gestational age, 30 +/- 2 weeks) who required a ventriculoperitoneal (VP) shunt for posthemorrhagic hydrocephalus (92% with Grade III or IV hemorrhage) were followed for neurodevelopmental problems. VP shunts were placed at a median age of 29 days (range, 18 to 87 days) after serial lumbar punctures failed to control progressive and symptomatic ventriculomegaly. A total of 34 infants (68%) required one shunt revision or more, and the overall infection rate per patient was 50%. Seven infants died, 2 from shunt infections. The infants were evaluated with audiological, ophthalmological, and neurodevelopmental examinations. Of the survivors, 11 (28%) have severe visual loss and 10 (24%) have hearing impairment. Of the infants, 21 (49%) have severe motor handicaps and 19 (38%) have seizure disorders. Developmental and motor scores were obtained using the Bayley or Knobloch-Gesell scales. Seven infants (18%) have normal developmental outcomes; 26 (60%) have multiple handicaps. Grade IV hemorrhage or the occurrence of seizures was a predictor of poor neurodevelopmental outcome. We conclude that progressive posthemorrhagic hydrocephalus in low birth weight infants is associated with multiple handicaps despite early VP shunt placement.

Cerebral Hemorrhage↗
PubMed1986

Central nervous system anomalies associated with meningomyelocele, hydrocephalus, and the Arnold-Chiari malformation: reappraisal of theories regarding the pathogenesis of posterior neural tube closure defects.

Complete gross and microscopic neuropathological examinations of 25 children who died with meningomyelocele, the Arnold-Chiari malformation, and hydrocephalus revealed a wide range and frequency of associated central nervous system malformations. The most remarkable of these anomalies were hypoplasia or aplasia of cranial nerve nuclei (20%), demonstrable obstruction of cerebrospinal fluid flow within the ventricular system (92%), cerebellar dysplasia (72%), a disorder of migration of cortical neurons (92%), fusion of the thalami (16%), agenesis of the corpus callosum (12%), and complete or partial agenesis of the olfactory tract and bulb (8%). The anomalies associated with posterior neural tube closure defects can no longer be considered secondary, but rather must be considered part of a spectrum of malformations caused by an unidentified primary insult to the central nervous system. The frequency and pattern of brain malformations associated with neural tube defects of some children with meningomyelocele suggest that such malformations may seriously affect intellectual outcome.

Arnold-Chiari Malformation↗
PubMed1985

Neurosurgical staging of midline intra-axial (nuclear) tumors.

A staging system is needed for midline intra-axial (nuclear) tumors so that treatment results can be compared, insights about tumor biology can be obtained, and prognosis can be estimated. The TNM staging classification is of limited value because nuclear tumor margins cannot be defined by an operation, there are no nodes to sample, and the tumors rarely metastasize. Nuclear tumors can be staged best now by computed tomography (CT) and pathology findings. Diagnostic staging by CT scans will demonstrate tumor features that may be of prognostic importance: tumor size, density, volume, enhancement, laterality, and presence of cysts and calcifications. In the current series, prognosis was better for tumors with cysts or calcifications, and for tumors less than 5 cm, but correlated poorly with laterality and site. Biopsy and often partial resection can be performed on nuclear tumors with low risks, but operative staging is not helpful because operations are necessarily limited. Most diencephalic tumors are astrocytomas or mixed gliomas, but approximately 15% are malignant astrocytomas or malignant mixed gliomas that need more intensive therapy, and 5% to 10% are neoplasms such as hamartomas that require no additional therapy. Two individual histopathologic characteristics, high cell density and mitoses, indicate a worse prognosis. Pediatric brain tumor study groups need to accumulate additional radiographic and pathologic information to stage nuclear tumors more accurately.

Brain Neoplasms↗
PubMed1985

Systemic staging of supratentorial extra-axial brain tumors in children. Craniopharyngiomas, atypical teratoma and teratoid tumors of the suprasellar region (germinomas), and intracranial teratomas.

A staging system has been proposed for the following tumors: craniopharyngiomas, germinomas, and intracranial teratomas. Various aspects of the specific pathologic and growth characteristics of the tumor determines such categorization and subclassification of the tumors. A brief analysis of the clinical aspects in reference to classification is presented. The suggested systems will need to be tested in clinical studies to determine their validity.

Brain Neoplasms↗
PubMed1985

Carpenter syndrome: natural history and clinical spectrum.

Recently, we evaluated three sibs with Carpenter syndrome, permitting further clinical, orthopedic, radiographic, and psychometric delineation of this disorder. All three patients were operated on for craniostenosis at or before 2 months. Although all had gross motor delay in early infancy, two had normal intelligence at 12 months and 10 years, respectively. Bony abnormalities contributed to functional impairment especially in the older children. Preaxial polydactyly of feet was present in all three affected sibs and in all other reported individuals with this condition, allowing differentiation of Carpenter syndrome from the other autosomal-recessive acrocephalopolysyndactyly syndromes.

Adolescent↗
PubMed1985

Identification of gonadotropin-releasing hormone in neurons of a hypothalamic hamartoma in a boy with precocious puberty.

We have studied a 3 1/12-year-old boy who presented with a hypothalamic mass and precocious puberty. His history suggested a course of isosexual precocity progressing from birth. Gelastic seizures also began at an early age. Endocrine evaluation revealed normal thyroid-stimulating hormone and growth hormone secretion, elevated basal and stimulated prolactin concentrations, and luteinizing hormone responses to sequential intravenous injections of gonadotropin-releasing hormone (GnRH) that were pubertal in pattern and magnitude. A needle biopsy of the mass recovered tissue that contained neurons histologically similar to those found in the normal hypothalamus, and the mass was characterized as a hypothalamic hamartoma. Immunohistochemical staining of this tissue with anti-GnRH antiserum demonstrated positive staining for GnRH immunoreactivity in neurons. This suggests a neurosecretory pathogenesis for the precocious puberty found in patients with hamartomas in the hypothalamic region.

Biopsy, Needle↗
PubMed1985

Laser injury of peripheral nerve: a model for focal endoneurial damage.

A model of endoneurial oedema is presented which produces localised nerve fibre injury including Wallerian degeneration, endoneurial oedema and increased endoneurial fluid pressure. A carbon dioxide laser was used to irradiate rat sciatic nerve and quantitative results were collected 2 days and 6 days after irradiation. The increase in endoneurial fluid pressure is compared with other models of Wallerian degeneration in which the entire fascicle was involved to aid in a comparative study of the role of oedema in neuropathy.

Animals↗
PubMed1985

Real time ultrasound diagnosis of hemorrhagic pathological conditions in the posterior fossa of preterm infants.

Real time echoencephalography (RTE) was used to diagnose and serially follow intracranial pathological conditions in the posterior fossa of infants with a gestational age of less than 34 weeks. The posterior fossa was studied in four planes (coronal, modified coronal, sagittal, and parasagittal) with a sector scanner equipped with a high frequency transducer that was placed on the fontanelles and the sutures. Hemorrhagic complications were easily differentiated from normal anatomy. RTE diagnosis was confirmed with computed tomographic scans (5 patients) and postmortem examination of the brain (18 infants). RTE is a precise and noninvasive technique to visualize hemorrhagic and other forms of abnormalities in the infratentorial compartment.

Cerebral Hemorrhage↗
PubMed1985

Experimental carbon dioxide laser brain lesions and intracranial dynamics: Part 1. Effect on intracranial pressure, systemic arterial pressure, central venous pressure, electroencephalography, and gross pathology.

Experimental brain lesions were created in the left parietooccipital cortex of the albino rabbit through the intact dura mater with high radiating carbon dioxide laser energy (40-watt impacts of 0.5-second duration for a total of 4 seconds on a 12.5-mm surface). Behavior, intracranial pressure (ICP), systolic arterial pressure (SAP), central venous pressure (CVP), electroencephalography (EEG), and gross pathology were studied at 2, 6, and 24 hours after the insult at a constant PaCO2 (38-42 torr). Disruption of the blood-brain barrier (Evans blue extravasation) was uniformly seen extending from the impact crater into the surrounding white matter in all groups. The ICP was elevated in sham-operated animals at 2 hours after the impact, and it remained elevated at 6 and 24 hours. The EEG revealed severe slowing with high voltage waves in the insulted left hemisphere. There was no change in mean SAP or CVP when compared to the sham-operated group. In the dexamethasone-pretreated group, there was a reduction of ICP when compared to the untreated group at 24 hours after the insult (P less than 0.005), but no changes in the gross pathology were noted.

Animals↗
PubMed1985

Experimental carbon dioxide laser brain lesions and intracranial dynamics: Part 2. Effect on brain water content and its response to acute therapy.

Experimental brain lesions were created over the left parietooccipital cortex of the albino rabbit through the intact dura mater with high radiating carbon dioxide laser energy (40-W impact, 0.5-second duration, for a total time of 4 seconds on a 12.5-mm surface). The brain water content was studied 2, 6, and 24 hours after the insult. Another two groups of animals received acute therapy with either dexamethasone (1 mg/kg) or furosemide (1 mg/kg). In all groups, Evans blue extravasation uniformly extended from the impact crater into the surrounding white matter. The brain water content in the gray matter was elevated from the control value by 2 hours after impact (P less than 0.005) and remained elevated at 6 and 24 hours. The white matter brain water content did not increase until 6 hours after impact and remained elevated in the 24-hour group (P less than 0.005). After dexamethasone treatment, there was a significant decrease of water in the gray matter (P less than 0.01), but not in the white matter. With furosemide therapy, there was no reduction of gray or white matter brain water.

Animals↗
PubMed1984

The occipital transtentorial approach to the posterior fossa in the pediatric patient.

The occipital transtentorial approach to the high posterior fossa has been previously described for the adult neurosurgical patient. In this presentation 5 pediatric patients with differing pathology in the posterior fossa are reported following successful occipital transtentorial operations. The advantages of this approach over the suboccipital route for microneurosurgery are discussed.

Astrocytoma↗