Calcium and phosphorus content of roots exposed to the oral environment

This study analyzed the calcium and phosphorus content of extracted tooth roots exposed to the in vivo oral environment. 20 teeth were obtained from 16 patients and divided into two groups of 10 teeth each. In group 1, the teeth had gingival probing depths of 5 mm or more, and teeth of group 2 had gingival recessions of 3 mm or more. Prior to extraction, the gingival margin location was recorded by placing a groove on the tooth surface. After extraction, the teeth were sectioned coronal-apically, air dried and coated with carbon. Energy dispersive X-ray spectra, excited in a scanning electron microscope, were analyzed to measure relative calcium and phosphorus contents and for calculation of their ratios. X-rays were collected from two positions on the sectioned root. Experimental positions were selected within the exposed portion of the roots of groups 1 and 2, and unexposed positions were selected from that portion of the same root with attached periodontal membrane. At each position, calcium and phosphorus content was measured at 4 depths into the root surface: in cementum, in dentin three-quarters of the distance to the pulp chamber, and at 2 locations in between on either side of the cemento-dentinal junction. Analysis of data demonstrated large variations in calcium and phosphorus content from surface to surface of individual teeth and from tooth to tooth in a subject. No statistically significant differences were found between experimental and unexposed locations. Calcium and phosphorus contents were greater in roots exposed to pockets when compared to roots exposed by recession at both experimental and unexposed locations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Thrombosed synthetic hemodialysis access fistulas: failure of fibrinolytic therapy

Seven episodes of acute thrombosis occurring in five patients with polytetrafluoroethylene dialysis fistulas were treated with local infusions of low-dose streptokinase. Bleeding from previous dialysis puncture sites necessitated stopping the infusion in six out of seven patients, although in one of these six, the graft reopened. The seventh patient had never been dialyzed through the graft and thrombolysis was achieved without incident. Surgery was avoided in only one patient. The authors contend that in these patients the risks of fibrinolytic therapy outweigh the benefits. Surgical thrombectomy, coupled with intraoperative angiography and possible angioplasty, is the preferred method of treating these patients. Venography prior to the creation of the fistula helps the surgeon avoid diseased vessels and may avert early failure of the fistula.     

Single-acquisition chemical-shift imaging of a binary system with use of stimulated echoes

A method for separating binary chemical-shift components with a single image data acquisition by means of stimulated echoes is demonstrated. With a strategy analogous to the modified Dixon method, three stimulated echoes were acquired to form three complex images. In each of the images, the complex pixel intensities were imparted, by design of the pulse sequence, with a phase factor carrying chemical-shift or field inhomogeneity information. With these three images, true fat/water separation can be obtained in biologic tissues. Studies at high field strength (4.7 T) on a toluene phantom, a pseudo-binary chemical-shift system, were used to evaluate the applicability of the method. Its clinical feasibility was demonstrated on a healthy human subject in a 0.6-T whole-body imaging system.     

Indwelling double-J ureteral stents for temporary and permanent urinary drainage: experience with 87 patients

Indwelling ureteral stents are a useful addition to the urologic armamentarium. The current double-J ureteral stent offers the advantages of ease of endoscopic insertion, exceptional patient tolerance and improved resistance to incrustation. We used these stents in 87 patients: to bypass obstruction in 57, as an adjunct to complicated upper tract surgery in 15, as initial treatment of upper urinary fistulas in 10 and for miscellaneous reasons in 5. The majority of the stents were placed endoscopically (58 per cent) and under local anesthesia (54 per cent). Half of the urinary fistulas healed without an operation and none of the patients treated with stents for malignant obstruction was hospitalized for more than 4 days. The stents were changed easily on an outpatient basis under local anesthesia and patient tolerance was excellent. When used as adjuncts to open procedures the stents frequently allowed for shorter hospital stay, since postoperative urinary drainage was decreased markedly. Of the 136 stents used in our series 13 became obstructed, usually after they were indwelling for more than 8 weeks. Irritative symptoms were noted in only 6 patients and responded well to pharmacologic therapy. We have found the double-J ureteral stent useful and reliable in patients with ureteral obstruction, as adjuncts to genitourinary surgery in selected instances and as internal diversion for upper urinary tract fistulas.