Biomedical subjects

S J O'Brien

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

At least 415 records · Page 23Linked to original sources

PubMedDate not supplied

Gene mapping in the spider monkey (Ateles paniscus chamek).

Sixteen isozyme markers have been assigned to the chromosome complement of the neotropical primate species Ateles paniscus chamek using three somatic cell hybrid panels. Several genetic associations were found to be common between humans and this species, despite the fact that Ateles is a karyologically rearranged taxon. Conversely, several human gene clusters were disrupted, resulting in gene associations not previously found in other primates. A comparison with other primates and mammalian orders, for which gene maps are available, was carried out for a comprehensive evaluation of genome evolution in these disparate taxa.

Animals↗

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Evolutionary conservation of ten microsatellite loci in four species of Felidae.

Short tandem repeat polymorphisms (STRP), or microsatellites, are widespread among vertebrate genomes and are useful in gene mapping and population studies due to a high level of length polymorphism. We describe here the isolation, characterization, and PCR amplification of 10 microsatellite loci from the domestic cat, Felis catus. The flanking primer sequences were conserved among other Felidae species, and amplification products demonstrated abundant polymorphism in puma, lion, cheetah, and domestic cat. The cheetah sample exhibited the lowest level of polymorphism for these loci among felid species.

Animals↗

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Molecular phylogeny of the red panda (Ailurus fulgens).

The phylogenetic placement of the red panda (Ailurus fulgens) and the giant panda (Ailuropoda melanoleuca) has been an evolutionary enigma since their original descriptions in the nineteenth century. A series of recent molecular analyses led to a consensus that the giant panda's ancestors were derived from early bears (Ursidae), but left unsettled the phylogenetic relationship of the red panda. Previous molecular and morphological phylogenies were inconclusive and varied among placement of the red panda within the raccoon family (Procyonidae), within the bear family (Ursidae), or in a separate family of carnivores equidistant between the two. To examine a relatively ancient (circa 20-30 million years before the present, MYBP) phylogenetic divergence, we used two slowly evolving genetic markers: mitochondrial 12S rRNA sequence and 592 fibroblast proteins resolved by two dimensional gel electrophoresis. Four different carnivore outgroup species, including dog (Canidae: Canis familiaris), cat (Felidae: Felis catus), fanaloka (Viverridae: Fossa fossa), and mongoose (Herpestidae: Galidia elegans), were selected to identify the root of the phylogenetic topologies. Phylogenetic reconstruction by distance-based methods, maximum parsimony, and maximum likelihood clearly indicate a distinct bifurcation forming the Ursidae and the Procyonidae. Further, our data consistently place the red panda as an early divergence within the Procyonidae radiation and confirm the inclusion of giant panda in the Ursidae lineage.

Animals↗

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Chromosomal mapping of two members of the human glutamate dehydrogenase (GLUD) gene family to chromosomes 10q22.3-q23 and Xq22-q23.

Glutamate dehydrogenase (GLUD) is an important mitochondrial enzyme that participates in neuronal transmission by catalyzing the deamination of L-glutamate, which serves as a potent excitatory neurotransmitter. The direct involvement of GLUD in the pathogenesis of certain human neurodegenerative disorders has been suggested recently. To investigate its possible role in the induction and progression of these disorders, we have initiated studies focusing on the chromosomal organization of the several members of the GLUD family and their functional status. In the present study using a panel of human x rodent somatic cell hybrids and in situ hybridization to metaphase chromosomes, we documented that the members of the GLUD gene family are dispersed in the human genome. The functional GLUD1 gene was mapped to chromosome 10q22.3-q23, and an intronless processed gene (GLUDP1) to chromosome Xq22-q23, while the truncated intron-containing GLUD pseudogene GLUDP2 was also assigned on chromosome 10, but not closely linked to the GLUD1 gene. These results provide novel information concerning the chromosomal organization of the human GLUD gene family.

Animals↗

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Fractures about the orbit in professional American football players.

A retrospective review was performed of records for players who suffered fractures about the orbit during participation in officially sponsored activities of the National Football League from 1980 to 1997. Clinical information was obtained on 19 of 29 players who sustained orbital fractures. The most common signs and symptoms included decreased visual acuity (74%, 14), decreased eye movement (42%, 8), hyphema (37%, 7), and infraorbital numbness (21%, 4). The mechanisms of injury were a digital poke (74%, 14) and blunt facial trauma (26%, 5). There were significantly more orbital fractures than zygomatic fractures suffered by offensive linemen as compared with all other positions. Fifteen of 19 players were managed with surgical reconstruction; 4 players were treated nonoperatively. The mean time from injury to surgical procedure was 7.7 days (range, 0 to 42). The mean interval to follow-up was 45.6 months (range, 3 to 146). At follow-up examination, eight (53%) of the patients treated surgically still reported diplopia with upper field gaze. Three of the four patients treated nonoperatively were asymptomatic. The mean time lost from games or practice was 25 days (range, 5 to 56). Ultimately, 17 (89%) players with orbital fractures were able to return to full football activities. Two patients were unable to resume their careers because of residual visual impairment.

Adult↗

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The anatomy and histology of the inferior glenohumeral ligament complex of the shoulder.

The gross and histologic anatomy of the inferior glenohumeral ligament was studied in 11 fresh frozen cadaver shoulders. Arthroscopic observations of the joint capsule through the normal range of motion revealed that the inferior glenohumeral ligament is actually a complex of structures consisting of an anterior band, a posterior band, and an interposed axillary pouch. While these components of the inferior glenohumeral ligament complex were present in all 11 specimens, they were best demonstrated in some shoulders by placing the humeral head in internal or external rotation in varying degrees of abduction. Histologic examination of the joint capsule revealed that the anterior and posterior bands of the inferior glenohumeral ligament complex were readily identifiable as distinct structures comprised of thickened bands of well-organized collagen bundles. Although slight variations were noted in the attachment sites of the anterior and posterior bands to the glenoid, the inferior glenohumeral ligament complex was observed to attach to the humeral neck in one of two distinct configurations. A collar-like attachment, in which the entire inferior glenohumeral ligament complex attaches just inferior to the articular edge of the humeral head, was observed in six specimens. In the remaining five specimens, the attachment was in the shape of a "V," with the anterior and posterior bands attaching adjacent to the articular edge of the humeral head and the axillary pouch attaching at the apex of the "V" distal to the articular edge. The orientation and design of the inferior glenohumeral ligament complex supports the functional concept of this single structure as an important anterior and posterior stabilizer of the shoulder joint.

Arthroscopy↗

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The iliotibial band lateral sling procedure and its effect on the results of anterior cruciate ligament reconstruction.

The effect of iliotibial band "lateral sling" augmentation on long-term outcome in ACL reconstruction using free autogenous central-third patellar tendon was evaluated retrospectively. Eighty reconstructions were reviewed; the minimum followup was 2 years and the average was 4 years. Sixty percent of the procedures involved supplementation with a lateral sling. By both clinical evaluation and KT-1000 measurement, there were no differences in the results of patients with lateral sling augmentation and those without it. In addition, 40% of patients had chronic pain and/or swelling related to the lateral sling. We do not currently recommend the routine use of a lateral sling augmentation for ACL reconstruction using central-third patellar tendon.

Adolescent↗

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Patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers.

To determine if the incidence and patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers are different from those seen in individuals injured in nonskiing athletic activities, we reviewed the records of 150 patients with acute anterior cruciate ligament injuries. All patients had undergone arthroscopic evaluation within 21 days from the time of injury. There were 75 individuals who were injured while skiing and 75 individuals who sustained an injury in some other high-load athletic activity. Associated meniscal injury was documented at the time of arthroscopy and characterized by location, region, zone, depth, shape, size, and stability. Thirty-one of 75 skiers had an associated meniscal injury as compared to 47 of 75 of the nonskiers. This suggested a strong trend of decreased incidence of meniscal injury in the skier group, but the nonskiers had a higher incidence of major meniscal tears that required repair or partial meniscectomy. The location of the meniscal tear was also significantly different. The incidence of isolated lateral meniscal injury in skiers was higher than in nonskiers. There was a strong trend of increased incidence of medial meniscal involvement in the nonskiers than in the skiers. While there was no difference in the zone or region of tear between the two groups, the skier group was more likely to have a longitudinal tear of the posterior horn of the lateral meniscus. In both groups, lateral meniscal tears were more likely to require conservative treatment or partial meniscectomy while medial meniscal tears were more likely to be repaired than excised.

Adolescent↗

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Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest.

Although the semitendinosus and gracilis tendons have long been used in ligamentous reconstruction procedures of the knee, their anatomic relationships have not been explicitly detailed. Therefore, cadaveric dissections were performed on fresh-frozen adult knees to examine these relationships. Several key anatomic points are useful in the harvest of these tendons. Their conjoined insertion site is medial and distal to the tibial tubercle. They become distinct structures at a point that is farther medial and slightly proximal. Tendon harvest is facilitated by identifying the tendons proximal to this point. The superficial medial collateral ligament lies deep to the tendons in this area and should not be disturbed. The tendons are ensheathed in a dense fascial layer that may impede tendon stripping. The accessory insertion of the semitendinosus tendon (which was present in 77% of the knees dissected) should be identified and transected to avoid tendon damage at harvest. Knee flexion may reduce the risk of injury to the saphenous nerve as it crosses the gracilis tendon. Variation in tendon diameter affects graft strength.

Adult↗

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Arthroscopic assessment of the medial collateral ligament complex of the elbow.

The extent that the medial collateral ligament complex could be visualized by arthroscopy was determined in 10 fresh cadaveric elbows from 10 individuals. We carefully exposed the medial collateral ligament complex through a muscle-splitting incision before performing arthroscopy. The anterior and posterior bundles were identified and marked by placing 4.0 nylon sutures deep to the bundles to aid in arthroscopic visualization. A portion of the anterior bundle was visible in only one elbow and in that elbow only the most anterior 25% of the anterior bundle was seen. Attempts to visualize the anterior bundle through additional portals were unsuccessful. Varying the flexion angle of the cadaveric elbow from 0 degrees to 130 degrees also failed to improve visualization. Conversely, the entire posterior bundle, including humeral and ulnar insertion sites, could be seen in all 10 specimens using the posterior portals. We also noted that direct pressure was placed on the ulnar nerve in all specimens when the arthroscope or any arthroscopic instrument was advanced into the posteromedial gutter in contact with the posterior bundle because of its proximity immediately adjacent to the ulnar nerve. The inability to reliably see the anterior bundle and the humeral or ulnar insertion sites of this ligament may limit the value of the arthroscope when assessing medial collateral ligament injuries. Additionally, great care should be taken when using the arthroscope or other instruments in the posteromedial gutter because the ulnar nerve lies immediately adjacent to the thin posterior bundle and capsule.

Arthroscopy↗

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Isolated closure of rotator interval defects for shoulder instability.

Fifteen patients noted at surgery to have an isolated defect in the rotator interval and no other pathologic abnormality underwent closure of the defect as an isolated procedure for recurrent instability symptoms. Intraoperative assessment of each of these shoulders after the closure demonstrated adequate stability, and no other stabilization procedures were performed. The average age of the patients was 24 years, and 10 of the 15 patients were women. Examination under anesthesia revealed increased inferior translation in all patients, as illustrated by at least a 1+ sulcus sign. The rotator interval defect averaged 2.75 cm in width and 2.3 cm in height. The rotator interval defect edges were freshened and approximated (nine patients) or imbricated (six patients), depending on the anterior capsular laxity and the degree of glenohumeral joint translation possible. Followup averaged 3.3 years (range, 2.2 to 5.3), and all patients achieved either a good or excellent result using the American Shoulder and Elbow Surgeons evaluation scale and the Rowe rating scale. Although most patients with a defect in the rotator interval require a standard stabilization procedure as a supplement to closure of the defect, approximation or imbrication of the defect as an initial step at surgery may confer adequate stability in selected patients and obviate the need for formal capsular advancement.

Adolescent↗

PubMedDate not supplied

Reflex sympathetic dystrophy of the knee. Causes, diagnosis, and treatment.

Sixty patients with the diagnosis of reflex sympathetic dystrophy of the knee were evaluated retrospectively at our institution. The average followup was 2 years. Fifty-five (92%) patients treated with outpatient sympathetic blockade had resolution of the symptoms attributed to reflex sympathetic dystrophy. The time from onset of symptoms to initiation of treatment did not affect the ultimate outcome. The prognosis was most closely related to the presence or absence of an anatomic lesion that would continue to act as a painful stimulus. Eighty-one percent (29 of 36) of patients who had a significant anatomic lesion or surgical correction of a lesion had a complete resolution of their knee symptoms. However, only 21% (5 of 24) of patients with a persistent anatomic lesion in the knee had complete resolution. Fourteen patients required preliminary sympathetic blockade therapy before the underlying cause could be identified. This study emphasizes the need for establishing a precise diagnosis before contemplating any surgery of the knee, including arthroscopy. Arthroscopic procedures were the most common event precipitating reflex sympathetic dystrophy in this study.

Adolescent↗

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The active compression test: a new and effective test for diagnosing labral tears and acromioclavicular joint abnormality.

Labral tears and acromioclavicular joint abnormalities were differentiated on physical examination using a new diagnostic test. The standing patient forward flexed the arm to 90 degrees with the elbow in full extension and then adducted the arm 10 degrees to 15 degrees medial to the sagittal plane of the body and internally rotated it so that the thumb pointed downward. The examiner, standing behind the patient, applied a uniform downward force to the arm. With the arm in the same position, the palm was then fully supinated and the maneuver was repeated. The test was considered positive if pain was elicited during the first maneuver, and was reduced or eliminated with the second. Pain localized to the acromioclavicular joint or "on top" was diagnostic of acromioclavicular joint abnormality, whereas pain or painful clicking described as "inside" the shoulder was considered indicative of labral abnormality. A prospective study was performed on 318 patients to determine the sensitivity, specificity, and positive and negative predictive values of the test. Fifty-three of 56 patients whose preoperative examinations indicated a labral tear had confirmed labral tears that were repaired at surgery. Fifty-five of 62 patients who had pain in the acromioclavicular joint and whose preoperative examinations indicated abnormalities in the joint had positive clinical, operative, or radiographic evidence of acromioclavicular injury. There were no false-negative results in either group.

Acromioclavicular Joint↗

PubMedDate not supplied

Multiplanar analysis of acromion morphology.

To more completely describe acromion morphology and its relationship to impingement syndrome, we performed three-dimensional magnetic resonance imaging (N = 111) or computed tomography (N = 27) on 132 symptomatic shoulders. The mean patient age was 46.2 years (range, 14 to 86). Four parameters were evaluated: the angle of anterior slope of the acromion in the midsagittal and lateral-sagittal planes, lateral acromial angulation in the coronal plane, and the presence or absence of medial encroachment in the acromioclavicular joint. Twenty-five asymptomatic age-matched shoulders were used as controls. All imaging data were combined because no significant differences existed between the two imaging techniques. The mean acromion angle was 19.4 degrees in the midsagittal plane and 20 degrees in the lateral-sagittal plane. In the coronal plane, 97 (73%) acromions were neutral and 35 (27%) were downward sloping. Medial encroachment was present in 31 (24%) shoulders. Age distribution from the 2nd to 8th decade demonstrated a consistent and gradual transition from a flat acromion in the younger decades to a more hooked acromion in the older decades that was significant in both the midsagittal and lateral-sagittal planes. Furthermore, a greater percentage of patients were found to have downward angulating acromions with increasing age. Ninety-eight patients (74%) had stage II or III impingement. Of these shoulders, 39 (40%) had type I acromions, 51 (52%) type II, and 8 (8%) type III. Twenty-eight of 33 acromions with coronal lateral downward sloping had impingement, and all 31 shoulders with medial encroachment had impingement.

Acromion↗

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Contact with farming environment as a major risk factor for Shiga toxin (Vero cytotoxin)-producing Escherichia coli O157 infection in humans.

In a prospective, unmatched case-control study of sporadic Shiga toxin (Vero cytotoxin)-producing Escherichia coli O157 (STEC O157) infection in England, exposure to the farming environment emerged strongly as a risk factor (adjusted odds ratio = 2.45; 95% confidence intervals = 1.49-4.02; p=0.0004) posing further challenges and opportunities for prevention.

Abdominal Pain↗

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The developmental anatomy of the neonatal glenohumeral joint.

The embryologic development of the capsular ligaments, synovial lining, rotator cuff, and bony structures of the shoulder is incompletely understood. The purpose of this study is to report the gross and microscopic anatomy of the developing glenohumeral joint on the basis of dissections of fetal shoulder specimens. After Institutional Review Board approval from our hospital, 51 shoulders in 37 fetal specimens were obtained from cases of fetal demise. The gestation time of these specimens ranged from 9 to 40 weeks. The morphology of the capsule, labrum, and associated ligaments were studied by dissection under a dissecting microscope. High-resolution radiographs were made, and sections were processed for routine histology. There was noted to be minimal variation in the shape and slope of the acromion. The coracoid was much larger in relation to the shoulder than in the mature shoulder. The coracoacromial ligament was grossly evident at this stage of development, with distinct anterolateral and posteromedial bands in this ligament. The inferior glenohumeral ligament was seen as a prominent thickening in the capsule, whereas the middle and superior glenohumeral ligaments were thinner and more difficult to identify as distinct structures. Upon histologic examination, the inferior glenohumeral ligament was seen to consist of several layers of organized collagen fibers. The inferior glenohumeral ligament inserted into the labrum and margin of the glenoid. The capsule was much thinner in the region superior to the inferior glenohumeral ligament. A rotator interval capsular defect was often present, and the coracohumeral ligament was seen as a distinct structure as early as 15 weeks. A bare spot in the glenoid was not observed. This study indicates that some of the important functional elements of the structure of the mature human shoulder are present early in development, including the glenohumeral and coracohumeral ligaments. The coracoacromial ligament plays a significant role in the formation of the coracoacromial arch in the neonatal shoulder. The presence of a capsular rotator interval indicates that this aspect of capsular anatomy is congenital.

Embryonic and Fetal Development↗

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Genetic heterogeneity and molecular epidemiology of GB virus C/hepatitis G virus in China.

OBJECTIVE: The inter- and intrapatient genetic variation of GB virus C (GBV-C)/hepatitis G virus (HGV) was investigated to characterize the molecular epidemiologic profile of GBV-C/ HGV infection in China, an area endemic for viral hepatitis. The intrapatient variation of hepatitis C virus (HCV) from the same patients was compared to that of GBV-C/HGV. STUDY DESIGN/METHODS: GB virus C/HGV RNA was amplified by polymerase chain reaction in 88 patients with hepatitis C, hepatitis B or presumed non-A-E hepatitis from three cities in China. Five clones of the GBV-C/HGV NS3 region were sequenced from each GBV-C/HGV RNA-positive patient. The corresponding region of HCV was also sequenced from patients co-infected with HCV. Representative sequences of the GBV-C/HGV NS3 region from each patient and those of isolates from other continents were subjected to phylogenetic analyses. RESULTS: GB virus C/HGV was detected in 22 (25.25%) of 88 patients: 9 (21.4%) of 42 patients with presumed non-A-E hepatitis, 10 (27.7%) of 36 patients with hepatitis C, 3 (30.0%) in 10 patients with hepatitis B and C, and in none of 60 volunteer blood donors. The extent of nucleotide variation was less between Chinese isolates (2.4-17%; median, 10.4%) than between Chinese isolates and seven isolates from outside China (10.5-19.5%; median, 15.3%). Intrapatient sequence variation ranged from 0 to 1.75%, with a mean of 0.57 +/- 0.51%. Phylogenetic analysis grouped most Chinese isolates into four geographically specific clusters with a divergence of 10% to 16% from each other. The ratio of nonsynonymous to synonymous substitutions of GBV-C/HGV (Ka/Ks 0.019) was much lower than for HCV (0.071) in the same patients. CONCLUSION: Chinese isolates of GBV-C/HGV are genetically distinct. There are local strains as well as shared strains between different locales. The extent of amino acid sequence conservation suggests strong selection against nonsynonymous substitutions in the GBV-C/HGV genome.

China↗

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Molecular genetic divergence of orang utan (Pongo pygmaeus) subspecies based on isozyme and two-dimensional gel electrophoresis.

The orang utan (Pongo pygmaeus), as currently recognized, includes two geographically separated subspecies: Pongo pygmaeus pygmaeus, which resides on Borneo, and P. p. abelii, which inhabits Sumatra. At present, there is no known route of gene flow between the two populations except through captive individuals which have been released back into the wild over the last several decades. The two subspecies are differentiated by morphological and behavioral characters, and they can be distinguished by a subspecies specific pericentric chromosomal inversion. Nei-genetic distances were estimated between orang utan subspecies, gorilla, chimpanzee and humans using 44 isozyme loci and using 458 soluble fibroblast proteins which were resolved by two-dimensional gel electrophoresis. Phenetic analysis of both data sets supports the following conclusions: the orang utan subspecies distances are approximately 10 times closer to each other than they are to the African apes, and the orang utan subspecies are approximately as divergent as are the two chimpanzee species. Comparison of the genetic distances to genetic distance estimates done in the same laboratory under identical conditions reveals that the distance between Bornean vs. Sumatran orang utans is 5-10 times the distance measured between several pairs of subspecies including lions, cheetahs, and tigers. Near species level molecular genetic distances between orang utan subspecies would support the separate management of Bornean and Sumatran orang utans as evolutionary significant units (Ryder 1987). Evolutionary topologies were constructed from the distance data using both cladistic and phenetic methods. The majority of resulting trees affirmed previous molecular evolutionary studies that indicated that man and chimpanzee diverged from a common ancestor subsequent to the divergence of gorilla from the common ancestor.

Animals↗