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Biomedical subjects

J L Atkinson

Publications and source records attributed to J L Atkinson.

At least 55 records · Page 3Linked to original sources
PubMed1996

Spontaneous spinal cerebrospinal fluid leaks and intracranial hypotension.

Spinal cerebrospinal fluid (CSF) leaks are often implicated as the cause of the syndrome of spontaneous intracranial hypotension, but they have rarely been demonstrated radiographically or surgically. The authors reviewed their experience with documented cases of spinal CSF leaks of spontaneous onset in 11 patients including their surgical observations in four of the patients. The mean age of the six women and five men included in the study was 38 years (range 22-51 years). All patients presented with a postural headache; however, most had additional symptoms, including nausea, emesis, sixth cranial-nerve paresis, or local back pain at the level of the CSF leak. All patients underwent indium-111 radionucleotide cisternography or computerized tomographic (CT) myelography. The location of the spontaneous CSF leak was in the cervical spine in two patients, the cervicothoracic junction in three patients, the thoracic spine in five patients, and the lumbar spine in one patient. The false negative rate for radionucleotide cisternography was high (30%). Subdural fluid collections, meningeal enhancement, and downward displacement of the cerebellum, resembling a Chiari I malformation, were commonly found on cranial imaging studies. In most patients, the symptoms resolved in response to supportive measures or an epidural blood patch. Leaking meningeal diverticula were found to be the cause of the CSF leak in four patients who underwent surgery. In three patients these diverticula could be ligated with good result but in one patient an extensive complex of meningeal diverticula was found to be inoperable. Two patients had an unusual body habitus and joint hypermobility, and two other patients had suffered a spontaneous retinal detachment at a young age. In conclusion, spontaneous spinal CSF leaks are uncommon, but they are increasingly recognized as a cause of spontaneous intracranial hypotension. Most spinal CSF leaks are located at the cervicothoracic junction or in the thoracic spine, and they may be associated with meningeal diverticula. The radiographic study of choice is CT myelography. The disease is usually self-limiting, but in selected cases our experience with surgical ligation of leaking meningeal diverticula has been satisfactory. An underlying connective tissue disorder may be present in some patients with a spontaneous spinal CSF leak.

Adult↗
PubMed1996

Spinal shock.

The term "spinal shock" applies to all phenomena surrounding physiologic or anatomic transection of the spinal cord that results in temporary loss or depression of all or most spinal reflex activity below the level of the injury. Hypotension due to loss of sympathetic tone is a possible complication, depending on the level of the lesion. The mechanism of injury that causes spinal shock is usually traumatic in origin and occurs immediately, but spinal shock has been described with mechanisms of injury that progress over several hours. Spinal cord reflex arcs immediately above the level of injury may also be severely depressed on the basis of the Schiff-Sherrington phenomenon. The end of the spinal shock phase of spinal cord injury is signaled by the return of elicitable abnormal cutaneospinal or muscle spindle reflex arcs. Autonomic reflex arcs involving relay to secondary ganglionic neurons outside the spinal cord may be variably affected during spinal shock, and their return after spinal shock abates is variable. The returning spinal cord reflex arcs below the level of injury are irrevocably altered and are the substrate on which rehabilitation efforts are based.

Humans↗
PubMed1995

Contrast-enhanced radicular veins on MR of the lumbar spine in an asymptomatic study group.

PURPOSE: To determine whether radicular enhancement occurs in asymptomatic persons and, if so, to provide insight into the mechanism of such enhancement. METHODS: Thirty asymptomatic volunteers were studied with gadolinium-enhanced MR (0.1 mmol/kg) of the lumbar spine. The precontrast axial T1-weighted sequences were reviewed for the entry section phenomenon of flow-related enhancement. If present, the sequence was repeated in combination with a superior saturation pulse in an attempt to eliminate this phenomenon. All studies were reviewed to document the incidence of radicular enhancement and determine its association with the entry section phenomenon. RESULTS: The entry section phenomenon was observed in 16 of 30 volunteers with successful elimination obtained in all cases. Eighteen of the volunteers demonstrated radicular enhancement; 16 of the 18 enhancing roots were associated with the entry section phenomenon. CONCLUSIONS: Radicular enhancement occurs commonly in asymptomatic volunteers. This phenomenon most likely represents the enhancement of prominent radicular veins. We urge caution in interpreting this finding as abnormal in the symptomatic population with degenerative disk disease.

Adult↗
PubMed1994

Effect of insulin and isoproterenol on lipid metabolism in porcine adipose tissue from different depots.

Significant differences were found in the rates of lipogenesis, glucose oxidation and lipolysis in porcine adipose tissue from four depots; outer subcutaneous (OSC), middle subcutaneous (MSC), perirenal (PR) and omental (OM). Lipogenesis was stimulated by insulin in all depots in the order PR > OM > MSC > OSC. Lipolysis was stimulated by isoproterenol in all depots in the order PR > OM > MSC > OSC. Differences in lipid metabolism by the different depots may have an important impact on lipid accretion in vivo.

Adipocytes↗
PubMed1994

Frontal sagittal meningioma: tumor parasitization of cortical vasculature as the etiology of peritumoral edema. Case report.

Peritumoral edema surrounding meningiomas is poorly understood; however, several theories have been proposed in the literature. A case is presented here of a frontal sagittal meningioma symmetrically effacing both frontal lobes that subsequently evokes peritumoral edema on only one side. The tumor is histologically identical on the left and right sides. Angiograms were obtained that support previous work, which suggests that the degree of cortical parasitization of blood supply correlates with peritumoral edema whether or not tumor secretory factors are involved.

Adult↗
PubMed1994

Strain comparison of turkey egg components.

Two experiments were conducted to quantify the composition of turkey hatching eggs in relation to strain of bird and age of breeder. In one experiment, 20 Nicholas and British United Turkeys of America (BUTA) eggs produced at 3, 12, and 24 wk of production were examined for physical and chemical components. Eggs from Nicholas hens were always some 4 g heavier (P < .05) due essentially to a larger albumen content. Although absolute components increased over time (P < .05), there were few changes in proportional composition (P > .05). Eggs from BUTA turkeys initially contained more yolk protein (P < .05). At 12 and 24 wk of production, eggs from Nicholas hens changed most rapidly and at these ages contained more yolk protein than the BUTA strain eggs (P < .05). At the end of the production cycle, BUTA eggs contained less lipid and protein in the yolk (P < .05). For both strains there was an increase in stearic acid content of yolk lipid with increased breeder age. In a second experiment, comparable studies were conducted on eggs obtained from male and female line BUTA breeding stock. Although male line eggs were heavier (87 vs 78 g), the smaller female line eggs exhibited proportionally more yolk (P < .05), as absolute yolk weight was similar for both strains (22.4 vs 22.5 g). It was concluded that only minor differences exist in components of eggs from different turkey strains.

Age Factors↗
PubMed1994

Enhanced lumbar nerve roots in the spine without prior surgery: radiculitis or radicular veins?

PURPOSE: To evaluate the clinical significance of continuous intradural lumbosacral nerve root enhancement in symptomatic patients without prior lumbar surgery. METHODS: Fifty-three patients without prior back surgery, referred to our institution for evaluation of low-back pain and radiculopathy, were studied with gadolinium-enhanced MR (0.1 mmol/kg) of the lumbar spine. Scans were reviewed for the presence of lumbosacral nerve root enhancement and any associated nerve root compression. Results were correlated with clinical history and physical examinations. RESULTS: Seventeen continuously enhancing nerve roots and two enhancing fila terminale were observed in 13 patients. Eight of 17 (47%) had no referable symptoms. Nine of these nerve roots (53%) were not associated with any degree of nerve root compression. Seven cases (41%) were noted to have flow-related enhancement on the entry section of the T1-weighted axial sequence. CONCLUSIONS: Lumbosacral nerve root enhancement correlates poorly with clinical radiculopathy. The use of contrast enhancement to detect lumbosacral nerve root enhancement in cases in which the unenhanced scan is less than diagnostic is not warranted. The high association between lumbosacral nerve root enhancement and entry-section flow-related enhancement suggests that these enhancing structures within the cauda equina are vessels. It is likely that lumbosacral nerve root enhancement represents intravascular enhancement of radicular veins and not a breakdown in the blood-nerve barrier.

Adult↗
PubMed1993

Addition of microbial phytase to diets of young pigs.

Microbial phytase was added at concentrations of 0, 500, and 1,000 phytase units per gram (PU/g) to a diet that derived the majority of its phosphorus content from organic sources. In addition, a positive control diet was prepared by adding calcium phosphate to increase the total dietary phosphorus by 1.7 g/kg. Each diet was available ad libitum for 3 wk to nine individually penned pigs approximately 5 wk old and with an initial weight of 10.2 kg. Digestibility of phosphorus was estimated, using chromic oxide as an indicator, from fecal samples obtained during the 3rd wk of the trial. Blood serum and metatarsal bones were obtained at slaughter. The addition of the microbial enzyme resulted in increased rate and efficiency of gain, increased digestibility of dietary phosphorus, increased serum phosphorus, decreased serum alkaline phosphatase, and increased metatarsal ash and weight of metatarsal phosphorus. The response to dietary microbial phytase was similar to that resulting from feeding a diet containing 1.7 g/kg of additional phosphorus from calcium phosphate.

6-Phytase↗
PubMed1993

Spontaneous thrombosis of posterior cerebral artery aneurysm with angiographic reappearance. Case report.

The case is presented of a 23-year-old man suffering ischemic brain infarction from spontaneous thrombosis of a left posterior cerebral artery P1-P2 junction aneurysm. Vasospasm and/or partial parent vessel occlusion were documented by magnetic resonance (MR) imaging and angiography. Repeat cerebral angiography and MR imaging 3 months later revealed patency of the posterior cerebral artery and luminal filling of a 1-cm fusiform aneurysm, which was successfully trapped at surgery.

Adult↗
PubMed1992

Broiler weight gain and carcass composition when fed diets varying in amino acid balance, dietary energy, and protein level.

Three experiments were conducted with broiler chicks where diet composition varied with respect to dietary protein, energy, and essential amino acid (EAA) balance. Birds fed diets varying widely in EAA balance and protein and energy levels performed differently with respect to percentage carcass fat and protein. The absolute carcass protein deposition remained relatively constant between treatments, but body fat content varied depending on level of energy intake. Although abdominal fat content varied with level of dietary protein and energy, these values did not correlate well with total carcass fat deposition. Carcass fat deposition correlated well with dietary energy intake, which in turn appeared to be influenced by birds eating to satisfy their EAA requirement. With diets of similar EAA balance, birds appeared to have similar EAA intakes rather than similar energy intakes. Birds fed diets with similar EAA levels, but varying widely in level of nonessential amino acids, energy, or both consumed similar amounts of feed and deposited similar amounts of carcass protein. The present data suggest that level and balance of EAA can have a significant effect on feed intake, thereby influencing weight gain and carcass composition.

Adipose Tissue↗
PubMed1991

Intracranial cerebrovascular vasa vasorum associated with atherosclerosis and large thick-walled aneurysms.

Atherosclerotic plaques that develop in the extracranial circulation are usually extensively vascularized by vasa vasorum. However, human vasa vasorum associated with intracranial atherosclerosis has not been adequately addressed. Anterior and posterior circulation specimens from fresh autopsy material were studied under the magnification of a dissecting microscope and proliferative vasa vasorum was found to be frequently associated with intrinsic atheromatous plaques. Vasa vasorum associated with an incidental large aneurysm supports the radiological literature demonstrating that many large and giant thick-walled aneurysms exhibit vascularized walls on contrast computed tomography scans. This information may aid in the preoperative assessment and possible repair of these aneurysms.

Adolescent↗
PubMed1990

The effect of carbon dioxide on the diameter of brain capillaries.

Cerebral capillaries in cats subjected to variations in carbon dioxide tensions were studied using carbon black perfusion fixation. Five animals each were grouped into hypocapnia, normocapnia, and hypercapnia and 500 cortical, 250 white matter and 250 caudate nucleus capillaries per group were analyzed at 400 x magnification. Capillary diameters were found to change significantly in the cortex (6.1-10.0 microns), white matter (6.5-9.6 microns) and caudate nucleus (6.3-8.8 microns) from hypocapnia to hypercapnia, respectively. These findings suggest that capillary vasomotion occurs and that capillaries are not rigid tubes as previously portrayed.

Animals↗
PubMed1990

Effect of dietary tryptophan on plasma and brain tryptophan, brain serotonin, and brain 5-hydroxyindoleacetic acid in rainbow trout.

In order to determine the effect of dietary tryptophan level on plasma and brain tryptophan, brain serotonin, and brain 5-hydroxyindoleacetic acid levels, juvenile rainbow trout (Salmo gairdneri) were raised for 16 weeks on semipurified diets containing 0.06%, 0.16%, 0.21%, 0.26%, 0.39%, or 0.59% tryptophan. After 14 weeks, feed intake was depressed in fish fed the diets containing 0.06% or 0.16% tryptophan. No further differences in feed intake were noted between the remaining treatments. In addition, body weight was lower in fish fed diets containing 0.06%, 0.16%, or 0.21% tryptophan compared with fish fed higher levels. After 16 weeks of feeding the test diets, plasma tryptophan levels were found to be directly related to dietary tryptophan levels. Similarly, increased dietary levels of tryptophan resulted in increased brain levels of tryptophan, serotonin, and 5-hydroxyindoleacetic acid. These results demonstrate that in rainbow trout, as in mammals, altered dietary levels of tryptophan result in alterations in plasma and brain tryptophan, brain serotonin, and brain 5-hydroxyindoleacetic acid.

Journal Article↗
PubMed1990

Allergic nephropathy associated with ciprofloxacin.

We report a case of ciprofloxacin-related allergic tubulointerstitial nephritis, which manifested as nonoliguric renal failure, eosinophilia, and eosinophiluria. Our patient responded to discontinuation of ciprofloxacin therapy and oral administration of a brief course of corticosteroids. Although rare, allergic tubulointerstitial nephritis apparently can be caused by ciprofloxacin therapy. Clinicians should be aware of this entity.

Acute Kidney Injury↗
PubMed1990

A comparative study in opening and closing pressures of cerebral aneurysm clips.

Modern aneurysm clips with newer metallurgic properties and state-of-the-art designs have evolved through the years. Regretfully, manufacturers are still not required to provide product information regarding clip strength, and when such information is supplied, there is no interbrand consistency to how it is obtained. This experiment compares the closing pressures of 5 commonly used brands of aneurysm clips: Yasargil, Sugita, Sundt-Kees, Vari-Angle McFadden, and Heifetz. Interclip comparison is also made of opening pressures, that is, the arterial pressure required to open an aneurysm clip. Findings show a distinct difference in closing forces among these brands of aneurysm clips. The study of opening forces indicates that the important factors determining clip release or displacement were the failure of the clip to cross the vessel completely and intrinsic characteristics of the vascular wall.

Constriction↗
PubMed1989

Radiation-associated atheromatous disease of the cervical carotid artery: report of seven cases and review of the literature.

The natural history of postirradiation extracranial cerebrovascular disease is uncertain. Previous reported cases spanning 20 years of carotid surgery are difficult to evaluate, because patients may sometimes have unspecified symptoms, physical examinations, postoperative results, and follow-up. Also, the evolution of carotid surgery over the past two decades makes it impossible to compare earlier operative technique with the state-of-the-art technique of today. Our series of 7 patients underwent 9 carotid endarterectomies with an average follow-up period of 46 months. The number of patients is small, and although technically this is a more difficult operation, we feel the results are favorable and may be comparable with endarteerctomy procedures in nonirradiated patients. These patients should be approached as if radiation changes are not a major factor when they are considered for reconstructive arterial surgery.

Aged↗