Tungstate: a potent inhibitor of multifunctional glucose-6-phosphatase.

The insulin-like action of tungstate in diabetic rats (A. Barberà et al., 1994, J. Biol. Chem. 269, 20047-20053) prompted us to examine the effects of tungstate on the glucose-6-phosphatase system. Our results indicate that tungstate is a potent inhibitor of glucose-6-phosphatase, with a Ki in the 10-25 microM range determined with native microsomes and in the 1-7 microM range determined with detergent-treated microsomes. With both preparations, simple linear competitive inhibition was observed versus glucose 6-phosphate (glucose-6-P) as substrate with the glucose-6-P phosphohydrolase activity of the enzyme. Tungstate was a simple linear competitive inhibitor versus carbamyl phosphate (carbamyl-P) and a linear noncompetitive inhibitor versus glucose with the carbamyl-P:glucose phosphotransferase activity of the glucose-6-phosphatase system. These findings, in addition to the observation that tungstate protected the enzyme against thermal inactivation, indicate that tungstate binds with high affinity and competes at the active site of the enzyme where the substrates glucose-6-P and carbamyl-P bind prior to catalysis. Our results suggest that potent inhibition of glucose-6-P hydrolysis by tungstate is likely responsible, at least in part, for the normalization of glycemia and the rebound in hepatic glucose-6-P levels observed in earlier studies in which tungstate exhibited insulin-like action in diabetic rats.

Ileal hemorrhage caused by a parasitic uterine leiomyoma.

Parasitic uterine leiomyomas occur rarely and may present with a wide variety of symptoms. This report describes a uterine leiomyoma that became adherent to the distal ileum and caused massive lower gastrointestinal hemorrhage. The diagnosis was made preoperatively with a selective superior mesenteric arteriogram. The patient underwent an exploratory laparotomy, hysterectomy, and bowel resection, with subsequent resolution of symptoms. Pathologic evaluation revealed fibrous adhesions of the leiomyoma to the ileum, with bleeding from a dilated blood vessel in the submucosa of the bowel.

Rotator cuff sonography: a reassessment.

This study is both a retrospective and prospective evaluation of the clinical usefulness of shoulder sonography. Ninety-eight patients suspected of having rotator cuff tears underwent sonography of both shoulders. Sixty-two patients underwent double-contrast arthrography performed on the same day as sonography, and 38 patients underwent surgery after sonography. A comparison of the results from ultrasound and arthrography, using published diagnostic criteria, demonstrated a sensitivity of 75% and a specificity of 43% for detection of a rotator cuff tear. In this study, use of more restricted criteria, a subset of the published criteria, yielded a sensitivity of 68% and a specificity of 90%. A comparison of sonography with surgery, using this study's criteria, demonstrated a sensitivity of 57% and a specificity of 76%. This report shows that shoulder sonography is less reliable than previously reported and appears to have a very limited role in the evaluation of rotator cuff injuries.

Splenosis mimicking a renal mass.

Regenerated splenic tissue is commonly found after splenectomy. This tissue has been shown to have a desirable effect on postsplenectomy sepsis. Complications because of splenosis have been reported but are rare. The main significance of this tissue is to differentiate it from solid tumors which can be done most efficiently in a noninvasive fashion.

Computed tomography of renal angiomyolipoma presenting as right atrial mass.

Renal angiomyolipoma is a benign tumor with a propensity for extrarenal extension, although vascular invasion occurs only rarely. We present a case of an angiomyolipoma with extension via the left renal vein and inferior vena cava, into the right atrium.

Endometrial echo and its significance in female infertility.

The sonographic appearance of the endometrium was evaluated in 97 infertile women, 51 from a fertility unit (FU) and 46 from an in vitro fertilization (IVF) program. Three groups of patients were identified: those with normal findings, those with an incomplete endometrial echo, and those without any endometrial echo. Findings were correlated with the type of ovulation induction protocol, the peak estradiol level, and the number of successful pregnancies. In the IVF group, 72% of the patients did not exhibit normal endometrial echoes but had adequate estradiol levels, compared with 62% of the FU patients with normal endometrial echoes but significantly lower estradiol. The data suggest that IVF patients have a nonresponsive endometrium rather than inadequate estrogen stimulation and therefore that an endometrial abnormality may be an important cause of their infertility. Ultrasound may be used as a screening method to identify such patients.

Urosonography in spinal cord injury patients.

Urosonography, ultrasound of the urinary tract, is a noninvasive imaging method used to evaluate renal masses, renal parenchymal disease, hydronephrosis, bladder volume and calculi. The applicability of ultrasound was studied in 54 spinal cord injury patients by correlating uroradiological examinations with ultrasound. Emphasis was placed on ultrasonic imaging of ureterectasis and vesicoureteral reflux. Ultrasound confirmed all positive radiographic findings of renal and bladder abnormalities (renal calculi, chronic pyelonephritis, trabeculated bladder and bladder calculi), and yielded additional information in 27 per cent of the kidney and 13 per cent of the bladder studies. Ultrasound was used to confirm vesicoureteral reflux in 56 per cent of the patients and ureterectasis in 33 per cent. It is recommended that spinal cord injury patients undergo a baseline excretory urogram followed by periodical ultrasound examinations to detect hydronephrosis, renal parenchymal disease, and renal and bladder calculi, and to measure bladder volume and residual urine. Whenever real-time equipment and experienced ultrasonologists are available ultrasound can be used as an alternate to voiding cystourethrography to detect vesicoureteral reflux.

Hemodynamic assessment of transluminal angioplasty for lower extremity ischemia.

Seventy-two patients underwent hemodynamic testing before and after treatment for occlusive disease of their lower extremities. Percutaneous transluminal angioplasty (PTA) was used to treat lesions in 26 iliac segments and produced 23 initially improved ankle or upper thigh indices, two hemodynamic failures, and one technical failure; PTA for 54 femoropopliteal lesions produced initial hemodynamic improvement in 41 cases, three hemodynamic failures, and ten technical failures. Hemodynamic follow-up of the iliac segments showed improvement in 25 (92%) as measured by the systolic pressure index of the ankle; follow-up of the femoropopliteal segments showed continued patency of 41 (65.9%). The authors analyze these hemodynamic data.

Ultrasound assessment of normal renal dimensions.

This study confirms the accuracy and reliability of sonographic assessment of renal dimensions when meticulous scanning techniques are employed. Sonographic renal dimensions are smaller than those obtained by radiography, since there is neither the geometric magnification nor the change in size related to an osmotic diuresis from iodinated contrast material. Sonographically, with patients in the prone position, the mean right renal length was 10.74 cm (+/- 1.35 SD) and the mean left renal length was 11.10 cm (+/- 1.15 SD). A prospective sample demonstrated the mean depth (ventral-dorsal dimension) to be approximately 4.5 cm when the transducer was angulated for the lie of the kidney.

Ultrasound of the prostate. Analysis of tissue texture and abnormalities.

Thirty-nine patients with benign prostatic hypertrophy, prostatic carcinoma, or prostatitis underwent ultrasonography using a transabdominal suprapubic approach. In both benign hypertrophy and prostatitis, the gland was enlarged and exhibited a homogeneous echo pattern, being hypoechoic in prostatitis and either hypo- or hyperechoic in hypertrophy. Carcinoma was characterized by focal areas of increased or decreased echogenicity with irregular margins. The various sonographic appearances are explained by correlation with the histological findings, and the advantages of the transabdominal approach are discussed. The authors suggest that widespread application of this technique will improve early detection of prostatic carcinoma.

Percutaneous transluminal angioplasty: an angiographer's viewpoint.

We outline the present role of angioplasty in the management of peripheral vascular disease and its application to other portions of the arterial and venous systems; we summarize several large series, including our own, which encompass more than 4,000 cases; and we discuss the pathophysiology of balloon dilation techniques and the criteria for patient selection. With appropriate patient selection, initial (90%) and long-term (85%) patency results are now comparable with surgical techniques when the iliac arteries are involved. Treatment of femoropopliteal disease is slightly less successful but is indicated in appropriate patients. We present the role of angioplasty in conjunction with grafting procedures and in the management of renal vascular hypertension, and we review the potential complications (2% to 3%), adjunctive medical management, and areas for further investigation.