PubMed Health⌕ Search

Biomedical subjects

B A Green

Publications and source records attributed to B A Green.

At least 19 recordsLinked to original sources
PubMed1992

Acute traumatic central cord syndrome: MRI-pathological correlations.

The acute traumatic central cord syndrome (ATCCS) is commonly stated to result from an injury which affects primarily the center of the spinal cord and is frequently hemorrhagic. To test the validity of this widely disseminated hypothesis, the magnetic resonance images [MRI] of 11 consecutive cases of ATCCS caused by closed injury to the spine were analyzed and correlated with the gross pathological and histological features of 3 cervical spinal cords obtained at post mortem from patients with ATCCS, including 2 of patients studied by MRI. The MRI studies were performed acutely (18 h to 2 days after injury) in 7 patients and subacutely (3-10 days after injury) in 4. Ten of the 11 patients had pre-existing spondylosis and/or canal stenosis. The 11th suffered a cervical fracture. All patients exhibited hyperintense signal within the parenchyma of the cervical spinal cord on gradient echo MRI. None showed MRI features characteristic of hemorrhage on T1-weighted spin echo or T2-weighted gradient echo studies. Gross and histological examination of the necropsy specimens showed no evidence of blood or blood products within the cord parenchyma: the primary finding was diffuse disruption of axons, especially within the lateral columns of the cervical cord in the region occupied by the corticospinal tracts. The central gray matter was intact. In patients with ATCCS, the predominant loss of motor function in the distal muscles of the upper limbs may reflect the importance of the corticospinal tract for hand and finger function in the primate. In this study, the MRI and pathological observations indicate that ATCCS is predominantly a white matter injury and that intramedullary hemorrhage is not a necessary feature of the syndrome; indeed, it is probably an uncommon event in ATCCS. We suggest that the most common mechanism of injury in ATCCS may be direct compression of the cervical spinal cord by buckling of the ligamenta flava into an already narrowed cervical spinal canal; this would explain the predominance of axonal injury in the white matter of the lateral columns.

Adult↗
PubMed1992

An examination of dietary intakes and nutritional status of chronic healthy spinal cord injured individuals.

To examine the nutritional composition of the dietary intake of chronic healthy spinal cord injured (SCI) individuals, 33 subjects affiliated with 3 SCI rehabilitation centers logged their food consumption for 7 days. Prior to record keeping, subjects were trained by a registered dietitian on the accurate recording of their standard food choices and portion size, and were provided with scales to weigh food accurately. Dietary macro and micronutrients were analyzed with a computer software package, with nutritional analysis compared to the recommended daily allowances (RDA) of the Food and Nutrition Board of the National Academy of Sciences. Analysis showed caloric intake to be 75% of that recommended for able bodies persons, with a high reliance on fat for calories. Fat intake accounted for 37.9% of calories, well above the recommended level of 30%, but typical of the American diet. The ratio of polyunsaturated to saturated fat was approximately one half the recommended level, with carbohydrate calories averaging 16.5% below optimal RDA. Protein consumption was within normal range, but average dietary fiber was only 25% of recommended levels. Micronutrient analysis showed deficiencies in both water and fat-soluble vitamins, with suboptimal intake of multiple minerals. Given the apparent reliance on a high-fat and low-carbohydrate diet, this research shows that nutritional intervention and education of SCI persons are needed, and that a registered dietitian should be included in the SCI health care team.

Adolescent↗
PubMed1992

Hypothermia in spinal cord injury.

Early investigations involving central nervous system (CNS) temperature lowering to protect against the detrimental effects of hypoxia and ischemia were based on the observation that hypothermia reduces brain metabolism and energy consumption. The protective effects of hypothermia have been demonstrated in numerous experimental models of cerebral ischemia and recently in models of brain trauma. These observations also led to the application of hypothermia, in the form of local spinal cord cooling (LSCC), in animal models of experimental spinal cord injury (SCI). Although some investigators have reported negative results in studies of LSCC following traumatic SCI, the majority of studies have noted beneficial effects. The favorable results in animal experimentation led to a limited number of cases where LSCC was used in the treatment of human SCI. However, results are difficult to interpret because (1) most investigators report only a small number of cases, (2) the studies lack a control population, (3) the time interval from injury to the application of cooling has been highly variable, and (4) several investigators combined drug treatments with LSCC. In these experiments, LSCC was achieved via perfusion with a cold solution or an epidural heat exchanger and the aim was to lower cord temperatures significantly (about 10 degrees C). The application of the technique itself is fraught with difficulties. It requires acute surgery in a traumatized patient, a wide multilevel laminectomy, and minimizing the time interval between injury and the application of spinal cord cooling. Recent studies in experimental brain ischemia strongly suggest that a drastic lowering of CNS temperature may be unnecessary to lessen the degree of tissue damage occurring following an ischemic brain injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Reversal of adaptive left ventricular atrophy following electrically-stimulated exercise training in human tetraplegics.

Left ventricular (LV) myocardial atrophy and diminished cardiac function have been shown to accompany chronic human tetraplegia. These changes are attributable both to physical immobilisation and abnormal autonomic circulatory regulation imposed by a spinal cord injury (SCI). To test whether exercise training increases LV mass following chronic SCI, 8 neurologically complete quadriplegic males at 2 SCI rehabilitation and research centres underwent one month of electrically-stimulated quadriceps strengthening followed by 6 months of electrically-stimulated cycling exercise. Resting M-mode and 2-D echocardiograms were measured before and after exercise training to quantify the interventricular septal and posterior wall thicknesses at end-diastole (IVSTED and PWTED, respectively), and the LV internal dimension at end-diastole (LVIDED). LV mass was computed from these measurements using standard cube function geometry. Results showed a 6.5% increase in LVIDED following exercise training (p less than 0.02), with increases in IVSTED and PWTED of 17.8 (p less than 0.002) and 20.3% (p less than 0.01), respectively. Computed LV mass increased by 35% following exercise training (p = 0.002). These data indicate that myocardial atrophy is reversed in tetraplegics following electrically-stimulated exercise training, and that the changes in cardiac architecture are likely to be the result of both pressure and volume challenge to the heart imposed by exercise.

Adaptation, Physiological↗
PubMed1991

The e (P4) outer membrane protein of Haemophilus influenzae: biologic activity of anti-e serum and cloning and sequencing of the structural gene.

Outer membrane proteins of nontypeable (NT) Haemophilus influenzae are among the major candidates for inclusion in vaccines against these organisms. This article reports the purification of the e (P4) lipoprotein of H. influenzae and the subsequent production of antiserum directed against this protein. The anti-e polyclonal serum cross-reacted with e protein in multiple clinical NT H. influenzae isolates. Monoclonal antibody analysis of e protein showed at least one surface-exposed epitope to be conserved among NT H. influenzae strains. Anti-e serum also had bactericidal activity against multiple clinical isolates of NT H. influenzae. These results are in contrast to previous reports in the literature that purified P4 protein did not elicit biologically active antibodies. Anti-e antibodies exhibited synergistic bactericidal activity directed against NT H. influenzae when mixed with antibodies directed against another Haemophilus lipoprotein, PCP. This bactericidal synergy was observed against a variety of NT clinical isolates. We also report the cloning of the Haemophilus e lipoprotein, or hel, gene encoding the e protein and its expression and processing in Escherichia coli. The nucleotide sequence of the gene and deduced amino acid sequence of the protein are given. These results demonstrate that e protein is a viable candidate to be a component of a vaccine against NT H. influenzae.

Amino Acid Sequence↗
PubMed1991

Complications of epidural anesthesia: MR appearance of abnormalities.

Eight patients with acquired intradural arachnoid abnormalities caused by epidural anesthesia were evaluated with magnetic resonance (MR) imaging (eight patients) and intraoperative ultrasound imaging (four patients). Subarachnoid cysts were found in the lower cervical and thoracic spine in six patients. Irregularity of the surface of the cord was noted in seven cases. Associated intramedullary cysts and myelomalacia were seen in two patients. Arachnoiditis was unsuspected clinically in four patients; findings at MR imaging first suggested the cause of the patients' symptoms. The underlying mechanism for the intradural and cord abnormalities in seven of the eight patients was a chemically induced arachnoiditis produced by the administration of epidural anesthesia; in the eight case, an infection introduced at the time of the epidural injection was the cause of the abnormalities. The authors postulate that the preservative agents in the vials of anesthetic may have been the causative factor of this inflammation in the majority of the cases.

Adult↗
PubMed1991

Isoflurane-induced attenuation of motor evoked potentials caused by electrical motor cortex stimulation during surgery.

Dysfunction of spinal motor conduction during surgical procedures may not be reflected by changes in somatosensory evoked potential waveforms. A method of monitoring that allows direct and continuous assessment of motor function within the central nervous system during surgery would be useful. This paper describes one such method utilizing noninvasive electric cortical stimulation to evoke muscle activity (the motor evoked potential, or MEP) during surgery. The effect of isoflurane (superimposed on a baseline of N2O/narcotic anesthesia) on MEP's in response to cortical stimulation is specifically examined. Eight patients undergoing elective neurosurgical operations were included in the study. All patients received a background of general anesthesia and partial nondepolarizing neuromuscular blockade. The motor cortex was stimulated electrically via self-adhesive scalp electrodes. Electromyographic responses from multiple muscles were measured with subdermal electroencephalograph-type needle electrodes. Motor responses to stimulation were continually recorded on magnetic tape for off-line analysis. Once closing of the surgical incision was begun, a series of four to five stimuli of constant magnitude were applied to obtain "baseline" MEP responses. Patients were then ventilated with isoflurane for up to 8 minutes, during which time stimuli were continued every 15 to 20 seconds. Comparison was made of MEP responses for trials before, 1 minute after, and 5 minutes after the addition of isoflurane. All patients demonstrated reproducible motor responses to cortical stimulation during surgery. Addition of isoflurane [isoflurane)exp, less than or equal to 0.5%) to pre-existing anesthesia caused marked attenuation of MEP amplitudes in all patients within 5 minutes of its application, without affecting neuromuscular transmission as judged by direct peripheral nerve stimulation. It is concluded that: 1) monitoring motor system integrity and function with electric transcranial cortical stimulation during surgery is feasible when utilizing an N2O/narcotic anesthetic protocol; and 2) the quality of data obtained will likely suffer with the addition of isoflurane.

Adult↗
PubMed1991

Traumatic occipitoatlantal dislocation.

Four patients with traumatic occipitoatlantal dislocation are presented. The dislocations were the result of rapid deceleration motor vehicle accidents. The mechanism of injury was by hyperextension-rotation combined with a distraction force. Three patients sustained multiple injuries. Neurologic findings were variable. One patient with complete cord transection and closed head trauma died 4 days after the injury. In the three surviving patients, the occipitoatlantal dislocation was not diagnosed by the initial examiner. Prompt recognition and stabilization are essential to avoid further neurologic injury. Care must be taken not to increase the dislocation. A halo applied before operation facilitates reduction and allows posterior occipitoatlantal fusion to be performed under optimum conditions.

Accidents, Traffic↗
PubMed1990

A new mapping study of superoxide free radicals, vascular permeability and energy metabolism in central nervous system.

To study the role of free radicals in various pathophysiologies in the central nervous system (CNS), we have introduced a new simultaneous mapping technique of superoxide free radicals, vascular permeability and energy metabolism. The detection of superoxide anion in the CNS is based on the 380 nm chemiluminescence of 2-methyl-6-phenyl-3,7-dihydroimidazo [1,2-alpyrazin-3-one(CLA-phenyl)] upon reaction with superoxide in the frozen tissue section. The results show topographical relationships between activation of superoxide free radicals, increased vascular permeability, and changes of hydrogen transport system in the energy metabolism (Fig. 2). Prolonged formation of superoxide free radicals in the white matter without vasogenic oedema and necrotic tissue are interesting as a mechanism of progression of secondary tissue damage in ischaemic insults.

Animals↗
PubMed1990

A recombinant non-fatty acylated form of the Hi-PAL (P6) protein of Haemophilus influenzae elicits biologically active antibody against both nontypeable and type b H. influenzae.

An approximately 15,000-dalton outer membrane lipoprotein of Haemophilus influenzae, the Hi-PAL (P6) protein, has been shown to elicit bactericidal and protective antibodies against both type b and nontypeable H. influenzae strains and is a vaccine candidate for these organisms. To determine whether the lipid modification of this protein is required for immunogenicity or the elicitation of biologically active antibodies, a genetic fusion was constructed that contains the sequence of mature Hi-PAL fused to the polylinker region of pUC19. The protein expressed by this clone does not contain detectable lipid and was purified to homogeneity. This recombinant fusion protein, rPAL, elicited a strong immune response when injected into rabbits, and the antiserum reacted well with native Hi-PAL. The antiserum was bactericidal against a number of clinical nontypeable strains, duplicating the activity of anti-Hi-PAL. The anti-rPAL antiserum was also protective against type b bacteremia in the infant rat model. These results demonstrate that purified rPAL elicits antibodies with biological activities that are similar to those of anti-Hi-PAL antibodies. Thus, the lipid component of Hi-PAL is not required for either immunogenicity or elicitation of biologically active antibodies.

Acylation↗
PubMed1990

Antigenic conservation of the 15,000-dalton outer membrane lipoprotein PCP of Haemophilus influenzae and biologic activity of anti-PCP antisera.

A gene from Haemophilus influenzae encoding an outer membrane lipoprotein of about 15,000 daltons and which comigrates with the peptidoglycan-associated lipoprotein (PAL) of H. influenzae on sodium dodecyl sulfate-polyacrylamide gel electrophoresis has been previously reported and designated pcp gene, and its product has been designated PCP. in order to obtain specific immunologic probes for the analysis of PCP expression, cellular location, and antigenic conservation in H. influenzae, pcp was fused to the lac polylinker region of plasmid pUC19 and the hybrid gene was expressed in Escherichia coli. PCP purified from these cells was used to generate rabbit and mouse polyclonal antisera and mouse monoclonal antibody against PCP. Western immunoblot analysis with anti-PCP monoclonal antibody demonstrated that PCP is present and antigenically conserved in 30 tested strains of H. influenzae, including 27 clinical nontypeable strains. Polyclonal antiserum against PCP killed 9 of 11 clinical H. influenzae strains in a complement-mediated bactericidal assay, and bactericidal activity was additive with bactericidal activity of antisera against PAL. These results indicate that PCP is a potentially valuable component for a subunit vaccine against nontypeable H. influenzae disease, especially in combination with PAL or other components.

Amino Acid Sequence↗
PubMed1990

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management.

One hundred four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.

Adipose Tissue↗
PubMed1990

Bone mineral density after bicycle ergometry training.

The effect of functional electrical stimulation (FES) cycle ergometry on bone mineral density (BMD) was investigated in six spinal cord injury (SCI) quadriplegic men. Each subject trained three days a week for six months on an FES cycle ergometer. Pretraining and posttraining BMD measurements of the proximal femur were performed using dual photon absorptiometry. Mean pretraining BMD (percent norm) for the femoral neck, Ward triangle, and trochanter were 66.65, 57.43, and 57.67, respectively. After six months of FES cycle ergometry, mean BMD measurements were 66.15, 57.07, and 55.13, respectively. There was no statistically significant difference between the pretraining and posttraining BMD measurements. All subjects were found to have osteoporotic proximal femurs when BMD was expressed as a percent of their age-matched controls. Bone mineral density measurements were subsequently performed on three additional men with SCI who had exercised for three years with the FES cycle ergometry modality. Their mean BMDs were not significantly different from the experimental group. This study demonstrated that six months of FES cycle ergometry did not produce an increase in BMD.

Absorptiometry, Photon↗
PubMed1990

Rehabilitation therapy for patients with long-term spinal cord injuries.

The functional effects of three types of therapy for subjects with long-term incomplete cervical spinal cord injuries were investigated. Men and women, aged 18 to 45 years, were assigned to one of four groups using a restricted randomization process. The training period was divided into two consecutive eight-week time blocks where subjects received either (1) supervised physical exercise therapy (PET), (2) neuromuscular stimulation (NMS), or (3) electromyographic (EMG) biofeedback. Group 1 received EMG biofeedback followed by PET; Group 2 received EMG biofeedback followed by NMS; Group 3 received NMS followed by PET; and Group 4 received 16 weeks of PET. Dependent measures (manual muscle tests, self-care scores, mobility measures, and voluntary EMG activity) were assessed before training, at eight weeks, and after 16 weeks of training. A significant improvement (p less than .05) across time was found on all dependent measures except voluntary EMG. No difference was found on comparisons between groups.

Adolescent↗
PubMed1989

Acquired spinal subarachnoid cysts: evaluation with MR, CT myelography, and intraoperative sonography.

Fifteen patients with acquired spinal subarachnoid cysts (14 surgically proved, one presumed) were evaluated preoperatively with immediate and/or delayed CT myelography (seven patients), MR (11 patients), or both (three patients). CT myelography separated subarachnoid cyst from myelomalacia and/or intramedullary cysts in four cases but failed to diagnose them in three, while MR accurately diagnosed subarachnoid cyst in all 10 cases that were also surgically proved. The results of these preoperative examinations were evaluated to determine the efficacy of each study in diagnosing subarachnoid cysts, ascertaining their extent and internal architecture, and detecting associated abnormalities of the spinal cord. In addition, during surgery these cysts were studied with sonography to gain an understanding of the pathophysiological mechanisms involved in their formation and propagation and to guide the surgeon in their decompression. On the basis of our experience, MR appears to be the most efficient preoperative study in diagnosing and characterizing acquired subarachnoid cyst and associated abnormalities. Intraoperative sonography provides a reliable means of ensuring adequate decompression of these cysts.

Adult↗
PubMed1989

Dural laceration occurring with burst fractures and associated laminar fractures.

The cases of sixty patients in whom a burst fracture of a thoracic or lumbar vertebral body had been treated with posterior instrumentation and arthrodesis less than two weeks after the injury were retrospectively reviewed. Thirty of the patients had an associated laminar fracture. Eleven of the thirty, all of whom had a lumbar fracture and a preoperative neurological deficit, were noted at operation to have dural laceration. In four of the patients who had dural laceration, neural elements were entrapped between the fragments from the laminar fracture. None of the remaining thirty patients who did not have a laminar fracture had dural laceration (p = 0.0002). Univariate and multivariate statistical analysis revealed no significant association of the dural laceration with the patients' age or sex, or with the radiographic characteristics of the spine. There was a significant association between dural laceration and neurological deficit (p = 0.0001). In our series, the presence of a preoperative neurological deficit in a patient who had a burst fracture and an associated laminar fracture was a sensitive (100 per cent) and specific (74 per cent) predictor of dural laceration. The presence of this fracture pattern and an associated neurological deficit also predicted a risk of dural laceration with entrapped neural elements. This information may influence decisions as to whether an anterior or a posterior surgical approach should be used in such patients.

Adolescent↗