Compartmental pressure monitoring after arterial reconstruction lacks clinical relevance

Anterior compartmental intramuscular pressure was studied by the continuous-infusion technique during and after arterial reconstruction of the abdominal or lower extremity vessels in 23 patients. Although there were significant differences between the mean pressures in those patients who had proximal or distal arterial reconstruction, the mean pressure did not increase in the sequential preocclusion, occlusion, and postoperative periods during a mean follow-up of 26 hours in proximal reconstructions and 19 hours in distal reconstructions. One patient had pressures consistent with a borderline compartmental syndrome but died of a ruptured left ventricle before complete correlation of the clinical course and pressures could be made. We conclude from this study that although routine measurement of compartmental pressures during arterial reconstruction of the lower extremities yields interesting findings, it makes no important contribution to the clinical management of the patient.     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.     

Hfq-dependent regulation of OmpA synthesis is mediated by an antisense RNA

This paper shows that the small RNA MicA (previously SraD) is an antisense regulator of ompA in Escherichia coli. MicA accumulates upon entry into stationary phase and down-regulates the level of ompA mRNA. Regulation of ompA (outer membrane protein A), previously attributed to Hfq/mRNA binding, is lost upon deletion of the micA gene, whereas overexpression of MicA inhibits the synthesis of OmpA. In vitro, MicA binds to the ompA mRNA leader. Enzymatic and chemical probing was used to map the structures of MicA, the ompA mRNA leader, and the complex formed upon binding. MicA binding generates a footprint across the ompA Shine-Dalgarno sequence, consistent with a 12 + 4 base-pair interaction, which is additionally supported by the effect of mutations in vivo and by bioinformatics analysis of enterobacterial micA/ompA homolog sequences. MicA is conserved in many enterobacteria, as is its ompA target site. In vitro toeprinting confirmed that binding of MicA specifically interferes with ribosome binding. We propose that MicA, when present at high levels, blocks ribosome binding at the ompA translation start site, which-in line with previous work-secondarily facilitates RNase E cleavage and subsequent mRNA decay. MicA requires the presence of the Hfq protein, although the mechanistic basis for this remains unclear.     

Cleveland clinic CorAide blood pump circulatory support without anticoagulation

The Cleveland Clinic CorAide left ventricular assist system consists of a permanently implantable centrifugal pump in which the rotating assembly is completely suspended and noncontacting. A series of chronic animal in vivo studies were conducted to evaluate the biologic effects of CorAide circulatory support without the use of anticoagulation therapy. The CorAide pump was implanted in six calves (five calves for 21 to 32 days and one calf for 95 days). The first five calves received intravenous heparin during the early postoperative periods (2-7 days). Heparin administration was then discontinued and no other anticoagulant drugs were used for the duration of the experiments. The last calf did not receive any anticoagulant except for a bolus dose of heparin (200 U/kg) during surgery. Hemodynamics were stable in all six calves, with a mean pump flow of 5.6+/-1.2 L/min and mean arterial pressure of 100+/-4 mm Hg. The blood pump surfaces were clean of thrombus in all six calves. Significant findings at autopsy were limited to one case of renal infarction. There was no incidence of mechanical failure, bleeding, or device infection. The CorAide pump can be safely run with minimal or no anticoagulant therapy.     

In vivo histologic and biomechanical characterization of a biodegradable particulate composite bone cement

A biodegradable particulate composite bone cement consisting of a crosslinked gelatin matrix and tricalcium phosphate particles was implanted intraosseously in rabbits for up to 12 weeks. Cured cylindrical implants were inserted in holes drilled in the proximal tibial metaphysis. Sequential fluorochrome labeling and radiographs were done, and specimens were processed for decalcified and nondecalcified histology. At 4 weeks, the cross-sectional diameter of the implant was slightly greater than at implantation. There was considerable dissolution of the matrix and some new bone ingrowth. At 12 weeks, the diameter was reduced to half the original diameter and bone had grown throughout the matrix. In the distal femur, freshly mixed cement was used to stabilize an osteochondral fracture. Mechanical testing of the cement-stabilized fracture revealed a decrease in compressive strength and modulus at 4 weeks followed by an increase to greater than initial values at 12 weeks. Over time, the osteochondral fragment subsided into the underlying cement, but the subsidence did not correlate with mechanical strength. This osteochondral fracture model permits measurement of the overall material properties of a cement simultaneously weakened by resorption and reinforced by ingrowing bone.     

Osteosarcomatosis

A review of the 690 cases of osteosarcoma in the radiographic file of the Armed Forces Institute of Pathology revealed 29 cases of "osteosarcomatosis" (multiple skeletal sites of osteosarcoma). Fifteen of these patients were 18 years old and under and manifested rapidly appearing, usually symmetric, sclerotic metaphyseal lesions. The remaining 14 patients were more than 18 years old and had fewer, asymmetric sclerotic lesions. In most patients (28 of 29), a radiographically dominant skeletal tumor was seen. Pulmonary metastases occurred in the majority of patients and were detected at the same time as the bone lesions. These 29 patients were studied with regard to demographic data and skeletal distribution and radiographic appearance of their lesions. As a result of the findings, a metastatic origin from a primary dominant osteosarcoma is favored over a multifocal origin as the basis for osteosarcomatosis. Osteosarcomatosis is more commonly encountered in the mature skeleton than has been previously recognized.     

Two-Generation Reproductive Toxicity Study of Dietary Tributyl Phosphate in CD Rats

Tributyl phosphate (TBP) was tested for reproductive toxicityin rats. Thirty weanlings/sex (F0) were exposed to TBP in thediet ad libitum at 0, 200, 700, or 3000 ppm for 10 weeks andthen randomly mated within groups for 3 weeks with continuedexposure. F0 parents and 10 F1 weanlings/sex/dose were necropsied,and adult reproductive organs, urinary bladders (both sexes),kidneys (males), and livers (females) were evaluated histologically.Thirty F1 weanlings/sex/dose continued exposure for 11 weeksand were bred as described above. F1 parents and P2 weanlings,10/sex/dose, were then necropsied as described above. Adulttoxicity was observed in both sexes and generations at 700 and3000 ppm; observations included reduced body weights, weightgain and feed consumption, urinary bladder epithelial hyperplasia(both sexes), renal pelvis epithelial hyperplasia only at 3000ppm (male kidneys), and centrilobular hypertrophy (female livers).At 200 ppm, transient reductions in body weight were observedin F0 and F1 females, with urinary bladder epithelial hyperplasiain F0 males and females and in F1 males. There was no evidenceof reproductive toxicity, of reproductive organ pathology, orof effects on gestation or lactation at any dose tested. Postnataltoxicity was evidenced by consistent reductions in F1 and F2pup body weights at 3000 ppm and by occasional weight reductionsin F2 litters at 700 ppm, and was associated with maternal toxicityobserved at these doses and times. Under the conditions of thisstudy, a NOAEL was not determined for adult toxicity; the NOAELfor reproductive toxicity was at least 3000 ppm and the NOAELfor postnatal toxicity was approximately 200 ppm.