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Biomedical subjects

J P O'Brien

Publications and source records attributed to J P O'Brien.

At least 73 records · Page 4Linked to original sources
PubMed1987

A model of chronic nerve compression in the rat.

This article describes a model of chronic nerve compression in the rat. The sciatic nerve of adult male Sprague Dawley rats was banded with a 1-cm Silastic tube for varying periods of time. Morphometric analysis, electrodiagnostic studies, and histological evaluation were carried out 3, 5, 8, and 12 months after banding. Histological evaluation at 3 months was normal. At 5 months perineurial thickening was demonstrated. In the periphery of the fascicles, segmental demyelination was noted; central fibers appeared normal. At 8 months there was further epineurial and perineurial thickening. Marked thinning of the myelin was noted in all fibers and evidence of Wallerian degeneration was apparent. Progressive connective tissue and nerve fiber changes were noted at 12 months. Nerve conduction studies after 3 months of compression demonstrated an increase in conduction velocity compared to the normal unbanded control nerves. Progressive slowing of conduction velocity was noted from 5 through 12 months.

Animals↗
PubMed1987

Vibratory sensory testing in acute compartment syndromes: a clinical and experimental study.

Invasive and noninvasive diagnostic testing was correlated in 11 patients with acute compartmental syndromes of the forearm. The excellent correlation between diminished perception of vibration and increasing compartmental pressure suggested that 256 cycle per second (cps) vibratory stimuli may be useful clinically in determining the appropriate time for surgical intervention in the acute compartmental syndrome. In 12 adult male volunteers, elevated compartment pressures were created in the anterior tibial compartment of the leg. A decrease in perception to 256 cycle per second (cps) vibratory stimulus was the earliest sensory abnormality to occur with elevated tissue compartment pressures. Analysis of variance showed significantly that 256-cps vibration was the most reliable and earliest sensory modality to change at pressures of 35 to 40 mmHg. These clinical and experimental findings support the use of the 256-cps tuning fork as a noninvasive diagnostic test in the evaluation of the patient with suspected acute compartment syndrome.

Adult↗
PubMed1987

Physical heterogeneity of neisserial lipooligosaccharides reflects oligosaccharides that differ in apparent molecular weight, chemical composition, and antigenic expression.

We studied the oligosaccharides (OS) of outer membrane lipooligosaccharides (LOS) of Neisseria gonorrhoeae and Neisseria meningitidis. OS from the LOS of an individual neisserial strain always eluted from Sephadex G-50S as multiple peaks; the polyacrylamide gel elution profiles were nearly identical to the polyacrylamide gel electrophoresis profiles of the sodium dodecyl sulfate-disaggregated native LOS from which the OS were derived. Neisserial OS coeluted with Dex14 to Dex27 dextran oligomers (Mr, 2,210 to 4,320). Monosaccharide composition varied among the several OS released from the LOS of a single strain. The two OS of a gonococcal strain sensitive to normal human serum (NHS) bacteriolysis (sers) varied in their ability to inhibit the binding of NHS immunoglobulin M to their parental LOS. The OS that was rich in hexosamines inhibited NHS immune lysis of its parent strain; the OS that was poor in hexosamines did not. We conclude that structural differences in their OS account for the Mr heterogeneity of the LOS of a strain.

Acetates↗
PubMed1987

Disc damage above a spondylolisthesis.

Fifty-two patients with low back pain and spondylolisthesis at L5/S1 had discograms performed at the L4/L5 level. Retrolisthesis at L4/L5 occurred in 44%, but no direct relationship was demonstrated between the extent of retrolisthesis and either the grade of spondylolisthesis or the presence of disc damage. There was an inverse relationship between the degree of spondylolisthesis and L4/L5 disc damage. Thirty-six patients were assessed for symptomatic pain reproduction during discography. Fourteen (39%) had normal nuclear morphology and no pain induction on injection. Twenty-two patients had disc damage and 11 (50%) had symptomatic pain induced by injection. These results were correlated with the discographic appearances.

Adolescent↗
PubMed1987

The rib deformity in adolescent idiopathic scoliosis. A prospective study to evaluate changes after Harrington distraction and posterior fusion.

A prospective study to investigate changes in the rib hump or rib deformity after correction of the lateral curvature in adolescent idiopathic scoliosis is reported. The operative treatment for 47 patients was by a Harrington distraction rod and posterior fusion. Before operation and at follow-up, measurements of the Cobb angle, of vertebral rotation, and of the rib deformity were taken. Despite operative correction of the lateral curve, there was a progression of the rib deformity in 64% of the cases after four years. Correction of the lateral curve may thus have no effect on vertebral rotation and cannot be guaranteed to effect a permanent reduction of the rib hump.

Adolescent↗
PubMed1986

Comparisons of preoperative and postoperative MMPI data in chronic back patients.

The purpose of this study was to analyze 42 patients disabled with low-back pain in order to assess Minnesota Multiphasic Personality Index (MMPI) changes before and after surgery, the predictive value of MMPI, the results of anterior lumbar fusion in one group of severely disabled lumbar low-back pain patients. Statistical analyses were performed to compare and contrast MMPI, pain assessment, functional and occupational levels, and disability index before and after surgery. The degree of morbidity of the patients preoperatively was severe. After surgery, the majority of the patients showed improvement in their overall status. The available evidence suggests the following: Improvement in physical condition can produce improvement in psychological test scores; The preoperative MMPI is not a reliable indicator of surgical success.

Back Pain↗
PubMed1986

Discogenic pain persisting despite solid posterior fusion.

Persistent back pain in the presence of an intact posterior fusion is commonly seen and is often regarded as being psychogenic in origin. This paper discusses five patients, all of whom were chronically disabled by such pain; all five had a confirmed posterior and/or lateral fusion. In each case lateral discography identified the disc within the fused segment as the source of symptoms and pain relief was obtained with an anterior interbody fusion. This source of pain should be considered as a possibility in similar cases of failed back surgery.

Adult↗
PubMed1986

Simultaneous combined anterior and posterior fusion. A surgical solution for failed spinal surgery with a brief review of the first 150 patients.

Simultaneous combined anterior and posterior fusion (SCAPF) is recommended for patients with severe disability and failed spinal operations. In 150 patients treated over the past five years, emphasis is placed on the evolution of the technique and the surgical principles that exclude decompression of the nerve roots. The available evidence suggests that 86% of the patients were improved; 60% were significantly improved.

Adolescent↗