DNA and Gene Therapy: Uncoating of Polyoma Pseudovirus in Mouse Embryo Cells

Pseudovirions (host DNA fragments encapsidated by polyoma virus-coat protein) and polyoma virions are produced after infection of primary mouse embryo cells with polyoma virus. Purified pseudovirions are adsorbed to, and uncoated by, mouse embryo cells. The evidence for this uncoating is based on the conversion by pancreatic DNase of the uncoated pseudovirus DNA from an acid-insoluble to an acid-soluble form. The implications of these experiments to the eventual use of DNA for gene therapy are discussed.     

Direct inhibition of rat leydig cell function by tamoxifen

The effects of tamoxifen on rat testicular steroidogenesis were studied using dispersed interstitial cells. Tamoxifen significantly inhibited LH-, and 8-bromo-adenosine 3′,5′-monophosphate (8-bromo-cyclic AMP)-stimulated testosterone synthesis in a dose-dependent manner. Tamoxifen (10^?5M) also reduced LH-stimulated cyclic AMP formation. The addition of equimolar concentrations of 17β-estradiol or tamoxifen separately to interstitial cells resulted in similar inhibition of LH-stimulated testosterone synthesis. When equimolar concentrations of 17β-estradiol and tamoxifen were added concomitantly to interstitial cells, the inhibition was additive. Present studies demonstrate that tamoxifen has direct inhibitory effects on testicular steroidogenesis: both at the plasma membrane resulting in decreased cyclic AMP formation and also at steps subsequent to cyclic AMP.     

Moderate acute exercise (70% VO2 peak) induces TGF‐β, α‐amylase and IgA in saliva during recovery

Strenuous exercise promotes changes in salivary IgA and can be associated with a high incidence of upper respiratory tract Infections. However, moderate exercise enhances immune function. The effect of exercise on salivary IgA has been well studied, but its effect on other immunological parameters is poorly studied. Thus, this study determined the effect of moderate acute exercise on immunological salivary parameters, such as the levels of cytokines (TGF‐β and IL‐5), IgA, α‐amylase and total protein, over 24 h. Ten male adult subjects exercised for 60 min at an intensity of 70% VO₂ peak. Saliva samples were collected before (‘basal’) and 0, 12 and 24 h after an exercise session. The total salivary protein was lower after 12 and 24 h than immediately after exercise, whereas α‐amylase increased at 12 and 24 h after exercise compared with basal levels. The IgA concentration was increased at 24 h after exercise relative to immediately after exercise, and there was no difference in the IL‐5 while TGF‐β concentration increased in recovery. In conclusion, 70% VO₂ peak exercise does not induce changes immediately after exercise, but after 24 h, it produces an increase in salivary TGF‐β without changing IL‐5.     

Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

Lower limb asymmetry and patellofemoral joint incongruence in the etiology of knee exertion injuries in athletes

The association between different knee exertion injuries and lower limb malalignments was studied in 121 male athletes with knee exertion injuries and in 20 male athletes without knee symptoms. The associations between different malalignments was also analyzed. Leg length inequality (LLI), knee valgus, and different indexes of patellofemoral joint congruence were measured using radiological methods. Male athletes with patellar apicitis (n = 59) had significantly more LLI (P less than 0.001) and patella alta (P less than 0.05) than athletes without knee symptoms. The knee valgus was of the same numerical value in the shorter and longer leg sides in subjects with LLI of at least 5 mm (n = 58). A positive correlation was found between lateral patellar displacement (LPD) and patella alta (LT/LP) (P less than 0.001). Negative correlations were found between the sulcus angle (SA) and the lateral patello-femoral angle (LPA) (P less than 0.001) as well as between the LPD and the LPA (P less than 0.001).     

Chondromalacia patellae: assessment with MR imaging

Magnetic resonance (MR) images of the posterior patellar hyaline articular cartilage were obtained in 23 subjects to determine if MR imaging could accurately demonstrate the patellar cartilage. Arthroscopy was used as the standard of reference. Three subjects were asymptomatic volunteers. In the remaining 20 who had patellofemoral pain, arthroscopy was performed before MR imaging in seven and afterward in 12; one did not undergo arthroscopy. MR imaging showed focal areas of swelling of the patellar cartilage, focal hypointensity, surface irregularity, areas of thinning, and areas of cartilage loss with exposure of subchondral bone. The surgical findings agreed with those from MR images in all seven patients who underwent arthroscopy before MR imaging and in ten of the 12 who underwent surgery afterward. MR imaging is an accurate means of examining the posterior patellar cartilage and should be considered as an alternative to diagnostic arthroscopy when chondromalacia patellae is suspected.     

Acute experimental cerebral ischemia: MR enhancement using Gd-DTPA

The effects of a paramagnetic contrast agent, gadolinium-DTPA (Gd-DTPA), on magnetic resonance (MR) imaging of acute cerebral ischemia was investigated in a feline model of middle cerebral artery occlusion. Imaging was performed both before and after administration of an intravenous dose of 0.2 mmol/kg of Gd-DTPA. The animals were then sacrificed for pathologic correlation. No changes in intensity or relaxation times were noted before or after Gd-DTPA administration in two animals with 2 hours of occlusion. Infarcts were noted before and after contrast enhancement in all six cats with ischemia of greater than 16-hours duration. Gd-DTPA caused significant increase in intensity of infarct but not in that of normal cerebral tissue. Rapid enhancement was visible in infarcts of 16-24 hours, but such enhancement was slower in infarcts of 72-168 hours, presumably owing to slowed inflow caused by increased vasogenic edema in the latter group. Contrast enhancement of acute cerebral ischemic lesions with Gd-DTPA offers no improvement in sensitivity of MR imaging, although the conspicuity of the lesion may be improved. Additionally, contrast media may provide potential temporal and pathophysiological data for better characterization of cerebral ischemia.     

The efficacy of prophylactic intravenous antibiotics in elective foot and ankle surgery

A retrospective chart review of 555 patients who received elective foot and ankle surgeries between 1995 and 2001 at 1 outpatient podiatric hospital clinic was performed to evaluate the efficacy of preoperative intravenous antibiotic use. Only those patients who were having elective foot or ankle surgery for the first time, were being followed up at the hospital's outpatient clinic, and had a nontraumatic cause for their surgery were included in this study. A wound was considered infected when purulent material from the wound sites was noted and an organism(s) was cultured. A wound complication was defined as a superficial dehiscence, edema, erythema, or stitch abscess. Three hundred six (55.1%) patients received a preoperative antibiotic and 249 (44.9%) patients did not. Of the 306 patients who received a preoperative antibiotic, 9 (1.6%) acquired a postoperative wound infection, whereas 8 (1.4%) of the 249 patients who did not receive preoperative antibiotics acquired a postoperative infection. A logistic regression model and chi square tests of association were used to determine if preoperative antibiotic use, age, gender, type of surgical procedure, operative time, tourniquet use, past medical history, and internal fixation were predictive of or associated with postoperative wound infection or complication. None of the study factors was predictive of postoperative wound infection or complication (P >.01). Preoperative antibiotic use was associated with surgical category and internal fixation use (P <.001) but not postoperative wound infection or complication (P >.01). The results suggest that prophylactic intravenous antibiotic use in routine elective foot and ankle surgery is not warranted.