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Although common disturbances of grazing lands like plant defoliation are expected to affect their sensitivity to increasing atmospheric CO2 concentration, almost no research has been conducted to evaluate how important such effects might be on the direct responses of rangelands to CO2. This growth chamber experiment subjected intact plant-soil cylinders from a Wyoming, USA, prairie to a 3-way factorial of CO2 (370 vs. 720 μL L−1), defoliation (non-clipped vs. clipped) and soil nitrogen (control vs. 10 g m−2 added N) under simulated natural climatic conditions. Above- and below-ground biomass and N dynamics of the functional groups C3 grasses, C4 grasses and forbs were investigated. CO2 and defoliation had independent influences on biomass and N parameters of these rangeland plants. Growth under CO2-enriched conditions enhanced above-ground biomass 50% in C3 grasses alone, while shoot N concentration declined 16% in both C3 and C4 grasses. Plant-soil 15N uptake was unaffected by CO2 treatment. In contrast, defoliation had no effect on biomass, but increased tissue N concentration 29% across all functional groups. Without additional N, forage quality, which is in direct relation to N concentration, will decline under increasing atmospheric CO2. Increased dominance of C3 grasses plus reduced forage quality may necessitate changes in grazing management practices in mixed-species rangelands. [ABSTRACT FROM AUTHOR]

We evaluated the effects of livestock grazing on C content of the plant-soil system (to 60 cm) of two semi-arid grasslands: a mixed-grass prairie (grazed 12 years), and a short-grass steppe (grazed 56 years). Grazing treatments included season-long grazing at heavy and light stocking rates, and non-grazed exclosures. Significantly higher soil C (0-30cm) was measured in grazed pastures compared to non-grazed exclosures, although for the short-grass steppe higher soil C was observed with the heavy grazing treatment only. Excluding grazing caused an immobilization of C in excessive aboveground plant litter, and an increase in annual forbs and grasses which lack dense fibrous rooting systems conducive to soil organic matter formation and accumulation. Our data indicate that higher soil C with grazing was in part the result of more rapid annual shoot turnover, and redistribution of C within the plant-soil system as a result of changes in plant species composition.

Rotator cuff impingement symptoms may arise from intrinsic pathologic shoulder lesions related to instability or from extrinsic factors, primarily involving the coracoacromial arch. This report describes 2 unusual cases in which extrinsic impingement resulted from a distal clavicular osteochondroma. In both cases symptoms resolved after resection of the osteochondroma.

Spinous process fractures typically represent avulsion injuries involving the lower cervical spine. This case report describes the clinical and radiographic findings in a patient with spinous process fractures at the T-2, T-3, and T-4 vertebral levels. The fractures, which were obscured on conventional radiographs by overlying osseous and soft-tissue structures, were optimally shown on axial and computer-reconstructed sagittal computed tomographic (CT) images. Although isolated spinous process fractures do not compromise spinal stability, chronic sequelae associated with fracture nonunion may occur if a fracture is not recognized and treated. Because conventional radiographic assessment of the thoracic posterior elements is often limited, cases of clinically suspected spinous process fracture often require CT evaluation to confirm the diagnosis.

The objective of this study was to assess the association of ossification of the coracoacromial ligament (CAL) observed on conventional radiographs with the presence of rotator cuff pathology as demonstrated by magnetic resonance imaging (MRI), arthrography, and/or surgery. Conventional radiographs (internal and external rotation and outlet and axillary views) on eight patients showed ossification of the coracoacromial ligament. Rotator cuff integrity was assessed by physical examination in all 8 patients, by arthrography in 3 patients, and by MRI in 2 patients. Surgery was performed on four of the patients. Physical examination showed impingement findings and decreased rotator cuff strength suggestive of rotator cuff disease in all eight patients. The arthrograms and MRI examinations showed the presence of full-thickness rotator cuff tears. Four of these patients underwent surgery and the rotator cuff defects were confirmed and repaired. Identification of ossification of the CAL on conventional radiographs should be recognized as strongly suggestive of associated significant rotator cuff pathology.

The size of the occipital horn of the lateral ventricles was determined on parasagittal ultrasound scans in premature infants. In 52 neonates without evidence of intracranial haemorrhage, the pulvinar-posterior horn wall distance measured an average of 11.6 mm +/- 2 mm. In infants with intracranial pathology, the average length of the occipital horn varied from 16.3 mm +/- 2.5 mm to 31.8 mm +/- 7.4 mm. An occipital horn measurement greater than 16 mm indicated ventricular enlargement. Occipital horn asymmetry also indicated ventricular dilatation. In normal neonates the side-to-side difference averaged 0.6 mm while in neonates with ventriculomegaly the mean difference was 2.6 mm. The occipital horn frequently represents the first and may represent the only portion of the lateral ventricle to enlarge. Precise measurement of the occipital horn dimension, therefore, represents an excellent method for the identification and follow-up of ventriculomegaly in premature neonates.

Two hundred and seventy-three ultrasound examinations in 140 premature infants were performed with a transportable real-time scanner. Evidence for intracranial pathology was found in 86 (61%) of infants. In 66 infants (47%) a hemorrhage and in 79 infants (56%) ventricular dilatation was present. Choroid plexus larger than 12 mm was suggestive for either a bleeding into or onto the plexus. Cavum septi pellucidi was present in 72% of examined infants.

In 34 consecutive infants admitted to the neonatal intensive care unit with birth weight of less than 1,500 g, 80 cranial real-time sonograms were obtained to determine the incidence of choroid plexus hemorrhage. Choroid plexus hemorrhage was diagnosed only in the absence of germinal matrix hemorrhage. Diagnostic criteria included choroid plexus nodularity, enlargement (greater than 12 mm in anteroposterior diameter), or asymmetry between right and left (greater than 5 mm). Ipsilateral intraventricular clots or occipital horn dilatation supported the diagnosis of choroid plexus hemorrhage in most cases. Choroid plexus hemorrhage appeared to be the sole bleeding site in 10 (59%) of the 17 patients with intracranial hemorrhage. Hemorrhage in the region of the caudate nucleus was seen in the other seven cases (41%). Ventricular dilatation and/or intraventricular hemorrhage accompanied nine (90%) of the 10 cases of choroid plexus hemorrhage. This study suggests that in very low-birth-weight premature neonates, the choroid plexus may be a more frequent site of intracranial hemorrhage than previously believed.

In the neonate, ventriculitis and inflammatory infiltration of the choroid plexus usually accompany meningitis. Intracranial sonograms were reviewed from six infants referred for evaluation because of clinically suspected or confirmed ventriculitis. Findings included ventricular dilatation with irregularity of the ventricular margins and increased periventricular echogenicity. The choroid plexus margins also appeared poorly defined with loss of the normally smooth contour. Echogenic material was seen within the lateral ventricles, and intraventricular septa formation resulted in ventricular compartmentalization. Parenchymal changes included periventricular cavitation and a diffuse increase in cortical echogenicity. The ventricular pathology was more apparent on sonograms than on computed tomographic scans obtained at comparable times. In particular, sonography better demonstrated the ventricular compartmentalization from intraventricular septum formation. Identification of such partial ventricular isolation is especially important when treatment involves intraventricular shunt placement or the administration of intraventricular antibiotics. This experience suggests sonography should be the initial imaging method for evaluating ventriculitis and its complications in the newborn.

Intracerebellar hemorrhage in premature infants represents a life-threatening event. Prompt diagnosis of this form of intracranial hemorrhage is crucial, as surgical intervention may dramatically improve the prognosis. Whereas clinical signs associated with posterior fossa pathology in infants remain nonspecific, ultrasound provides a rapid, noninvasive means of identifying this potentially treatable abnormality. A case is presented.

We investigated platelet count, bleeding time, platelet aggregation, prothrombin time, activated partial thromboplastin time, and fibrinogen level in 58 very low-birth-weight infants during the first postnatal day to determine the relationship between hemostatic disorders and intraventricular hemorrhage. Thirty-two of the 58 infants (55%) were found to have periventricular-intraventricular hemorrhage by computerized tomography or autopsy. Nine patients (16%) had subarachnoid hemorrhage only and 17 (29%) had no evidence of intracranial hemorrhage. Infants with IVH had a significantly lower mean platelet count than did infants with no SAH/IVH. However, only five patients with IVH had initial thrombocytopenia. The IVH group had a mean bleeding time which was significantly prolonged compared to that of the group without SAH/IVH. Similarly, patients with IVH had a mean platelet aggregation response which was significantly diminished in comparison to that of patients with no SAH/IVH. Infants with IVH had a significantly longer mean PT than did infants with no SAH/IVH. In addition, babies with IVH had a significantly longer mean APTT compared to that of babies without SAH/IVH. The groups did not differ significantly with respect to fibrinogen levels. Three infants with IVH had disseminated intravascular coagulation in the early neonatal period. These data suggest that disorders of platelet-capillary interaction and defects in the intrinsic and extrinsic coagulation pathways may play important roles in intraventricular hemorrhage in the premature infant.

Magnetic resonance imaging (MRI) is evolving as a particularly valuable diagnostic procedure in the evaluation of musculoskeletal pathology. To assess the role of MRI as applied to the shoulder, we examined eight normal volunteers, six patients with seven arthrographically proven rotator cuff tears and two patients with impingement symptomatology but with negative double contrast conventional and computed tomographic arthrography. The studies were performed on a 1-Tesla magnet operating at 0.5 Tesla. Coronal T1-weighted images were obtained in all cases and coronal spin density and T2-weighted pulse sequences were employed in two cases. In the normal individuals, the supraspinatus muscle and tendon could be consistently demonstrated. The proximal humeral marrow, the superior glenoid labrum, and the acromioclavicular joint could also be examined. Findings in patients with rotator cuff tears included: (1) hypointense gap within the supraspinatus muscle-tendon complex on T1-weighted sequences, (2) absence of a demonstrable supraspinatus tendon with narrowing of the subacromial space secondary to elevation of the humeral head, and (3) increased signal within the supraspinatus tendon on T2-weighted images. In the patients with impingement syndrome and negative arthrography, MR demonstrated elevation of the supraspinatus tendon with subacromial impingement in one case and a normal supraspinatus tendon in the other. Impingement on the coracoacroaminal arch causes progressive fibrosis, atrophy, and eventual tear of the rotator cuff. The potential applications of MRI relative to the shoulder include assessment of tendon retraction in patients with supraspinatus tears and noninvasive evaluation of patients with impingement syndrome, permitting etiologic determinations, hopefully before irreversible tendon injury has occurred.

Fifty patients with suspected internal derangement of the knee had arthroscopic examinations after MR imaging with both a standard T1-weighted spin-echo (SE) sequence and a three-dimensional (3-D) gradient-echo sequence. This series permitted correlative evaluation of 100 menisci and 50 anterior cruciate ligaments. Meniscal tears were diagnosed when intrameniscal signal communicated with the meniscal surface. Criteria for diagnosing anterior cruciate ligament disruption included absence or discontinuity of the ligament, ligamentous laxity, and hyperflexion of the posterior cruciate ligament. Arthroscopic surgery confirmed the presence of 39 meniscal tears and 11 anterior cruciate ligament tears in this population. The sensitivity and specificity of the SE sequence for the diagnosis of meniscal tears were 77% and 98%, respectively. The 3-D gradient-echo sequence had a sensitivity of 87% and a specificity of 88%. For disruption of the ligament, the SE technique had a sensitivity of 82% and a specificity of 95% and the 3-D technique had a sensitivity of 64% and a specificity of 100%. Although these differences in sensitivity and specificity are not statistically significant at the p less than .05 level, probably because of the small sample size, the results show the relative strengths and weaknesses of the two imaging sequences. These data suggest that because of the complementary results of the two MR techniques, both the SE and the 3-D gradient-echo sequences have a role in the diagnosis of knee injuries.