Color Doppler sonography in the evaluation of erectile dysfunction: patterns of temporal response to papaverine.

Most studies of duplex Doppler sonography for the assessment of erectile dysfunction involve determination of peak systolic velocities 5 min after intracavernosal injection of papaverine. The purpose of this study was to determine the effect of the timing of Doppler measurements of flow after papaverine injection for establishing the presence of arterial and venous abnormalities. Color Doppler sonography was performed in 75 patients for evaluation of vasculogenic impotence. After intracavernosal injection of 60 mg of papaverine, measurements of peak systolic and end-diastolic velocities were obtained in each cavernosal artery at 5-min intervals for a total of 30 min. A peak systolic velocity of less than 25 cm/sec was used as the threshold for arterial insufficiency. An end-diastolic velocity of greater than 5 cm/sec was used to predict venous incompetence. Scanning was performed for direct assessment of dorsal venous flow. Thirty patients were subsequently evaluated by cavernosometry and cavernosography. In most patients (76%), maximum response to papaverine was achieved within the first 5 min. In eight patients, significant increases in systolic velocity were seen only after 5 min. In 10 patients, significant changes in end-diastolic velocity between 5 and 30 min resulted in diagnostic reclassification. Data acquisition for 30 min significantly improved the sensitivity (95%) and specificity (83%) for the prediction of venous incompetence in patients with correlative cavernosography. Transient, early dorsal vein flow was noted in normal subjects. Persistent dorsal vein flow had an 80% sensitivity and 100% specificity for venous incompetence. Our results suggest that, when using color Doppler sonography, gathering data for 30 min may improve the prediction of vasculogenic impotence.     

Norepinephrine amplifies human chorionic gonadotropin-stimulated androgen biosynthesis by ovarian theca-interstitial cells

Ovarian theca-interstitial cells, when cultured in serum-free medium, secreted androgens in response to hCG stimulation. This production was dependent on time (maximum production attained after 96 h) and dose (half-maximal effective dose of hCG, 9 ng/ml). When the sympathomimetics norepinephrine, epinephrine, and isoproterenol were added to the medium, androgen production in response to hCG was enhanced by 100-300%. The ability of the catecholamines to stimulate androgen production was dependent on the continuous presence of hCG. Treatment with catecholamines alone did not induce theca-interstitial cells to produce androgens. Catecholamine stimulation of steroid hormone metabolism was selective for intermediates in the delta 4-pathway, with greatest increases occurring in the production of androstenedione and testosterone. It was found that the effect of the catecholamines on androgen production was dependent on both beta 1-and beta 2-adrenergic receptors. The acquisition of catecholamine responsiveness was specific to hCG; if theca-interstitial cells were induced to differentiate with either prostaglandin E2 or cholera toxin, then isoproterenol did not enhance androgen synthesis. The catecholamine-induced increases in androgen production were not due to a granulosa cell contribution of steroid. The interstitial cells are the only steroid-producing cells in the ovary that are directly innervated by norepinephrine-containing fibers of the sympathetic nervous system. Our finding of catecholamine-augmented androgen production provides a direct link between the autonomic nervous system and regulation of ovarian steroid synthesis.     

The primary plasminogen-activator inhibitors in endothelial cells, platelets, serum, and plasma are immunologically related.

Monospecific antiserum to an unusually stable Mr 50,000 plasminogen-activator inhibitor (PAI) purified from cultured bovine aortic endothelial cells was employed in conjunction with reverse fibrin autography to determine whether human platelets, serum, and plasma contain immunologically related inhibitors. Reverse fibrin autography revealed the presence of a Mr 50,000 inhibitor in the platelet and serum samples but not in normal plasma. However, a Mr 50,000 inhibitor was detected in plasma obtained from individuals with increased PAI activity. In each case, treatment of the sample with the anti-inhibitor serum removed the Mr 50,000 inhibitor. The inhibitor present in each sample neutralized exogenously added tissue-type plasminogen activator in a rapid manner. Inhibition was associated with the formation of a NaDodSO4-resistant enzyme-inhibitor complex of Mr 120,000. Again, treatment of the samples with the anti-inhibitor serum removed both the inhibitory activity and the component in these samples that binds to tissue-type plasminogen activator. Thus, the rapidly acting PAI present in human platelets, serum, and patient plasma is immunologically related to the PAI synthesized by cultured bovine aortic endothelial cells. This molecule may be the physiologically relevant inhibitor of plasminogen activator in the vascular system and, as such, may serve an important role in regulating the initiation of vascular fibrinolysis.     

Practical selection criteria for unenhanced cranial CT in patients with acute headache

We studied clinical predictors of cranial computed tomography (CT) abnormalities in patients with acute or acutely worsened headache. Data were collected from chart review of 333 consecutive patients presenting to an emergency department and who were clinically selected for cranial CT. Patients with a positive neurologic examination were at 10.7 times greater risk for a positive CT than the rest of the sample (p<1.5 – 10⁻¹⁰). Using only neurologic examination to select patients for CT would have missed 30.3% of the positive scans. The amnesia, depressed sensorium, and hypertension variables had CT yields approximating 10% or greater even in the presence of a negative neurologic examination. Together with a positive neurologic examination, these variables detected 87.9% of the patients in this sample with positive scans; their absence had a negative predictive value of 98.0%. Of the four patients with positive scans who would have been missed using this strategy, one was discharged directly from the emergency department anyway and the other three developed positive neurologic examinations within 24 hours. One died of causes unrelated to the intracranial pathology. Positive neurologic examination, hypertension, history of amnesia, or a depressed sensorium provide reasonable initial guidelines to select for CT patients with an acute headache.     

Viscoelastic properties of intervertebral disc cells. Identification of two biomechanically distinct cell populations

STUDY DESIGN: A combined experimental and theoretical biomechanical study to quantify the mechanical properties of living cells of the porcine intervertebral disc. OBJECTIVES: To quantify zonal variations in the mechanical properties and morphology of cells isolated from the intervertebral disc. SUMMARY OF BACKGROUND DATA: Cellular response to mechanical stimuli is influenced by the mechanical properties of cells and of the extracellular matrix. Significant zonal variations in intervertebral disc matrix properties have been reported. No information is currently available on the corresponding regional variations in the mechanical properties of intervertebral disc cells, despite evidence of significant differences in cellular phenotype and biologic response to loading. METHODS: The micropipette aspiration test was used in combination with a three-parameter viscoelastic solid model to measure the mechanical properties of cells isolated from the anulus fibrosus, transition zone, and nucleus pulposus. RESULTS: Intervertebral disc cells exhibited viscoelastic solid behaviors. Highly significant differences were observed in the morphology, cytoskeletal arrangement, and biomechanical properties of the nucleus pulposus cells as compared with anulus fibrosus or transition zone cells. Cells of the nucleus pulposus were approximately three times stiffer and significantly more viscous than cells of the anulus fibrosus or transition zone. CONCLUSIONS: The findings of this study provide new evidence for the existence of two biomechanically distinct cell populations in the intervertebral disc. These differences in mechanical behavior may be related to observed differences in the cytoskeletal architecture between these cells, and may further play an important role in the development, maintenance, and degeneration of the intervertebral disc.     

Color Doppler flow imaging

The performance requirements and operational parameters of a color Doppler system are outlined. The ability of an operator to recognize normal and abnormal variations in physiologic flow and artifacts caused by noise and aliasing is emphasized. The use of color Doppler flow imaging is described for the vessels of the neck and extremities, upper abdomen and abdominal transplants, obstetrics and gynecology, dialysis fistulas, and testicular and penile flow imaging.     

Heel ultrasonography is not a good screening tool for bone loss after kidney and pancreas transplantation

BACKGROUND: Solid organ transplant recipients, particularly simultaneous pancreas kidney recipients, are at high fracture risk. We tested whether quantitative ultrasonography (QUS) of the heel predicts bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA) in solid organ transplant recipients. METHODS: Thirty-eight transplant recipients (22 Female/16 Male) were studied. Spine and hip BMD was measured with a Hologic DXA scanner. 'Stiffness' of the heel was measured with a Lunar Ultrasound densitometer and compared with BMD by DXA. Contributing factors to bone loss were also assessed. RESULTS: Mean age was 43.1 +/- 1.3 yr. Simultaneous pancreas-kidney, kidney, and pancreas alone transplant recipients were assessed. Mean time post-transplantation was 3.0 +/- 0.6 yr. Mean DXA spine T-score was -1.15 +/- 0.22 (mean +/- SEM) and hip T-score was -1.22 +/- 0.20. There was no difference in mean T-score between women and men at the hip or spine. Mean right heel stiffness T-score was -0.97 +/- 0.25. There was no correlation between QUS and DXA at either the hip or spine in women or men. QUS had a false negative rate for identifying osteopenia or osteoporosis of 17% compared with DXA. The false positive rate for identifying osteopenia was 61%. CONCLUSIONS: The QUS is an unacceptable tool for identifying those at risk for bone loss after kidney or pancreas transplantation.     

Revision total knee arthroplasty with modular components inserted with metaphyseal cement and stems without cement

The clinical and radiographic outcomes of 50 consecutive revision total knee arthroplasties in 47 patients, placed with metaphyseal cemented femoral and tibial components with press-fit cementless stems, were reviewed at 36-month average follow-up. Revision was performed for aseptic loosening (11/50), infection (17/50), periprosthetic fracture (8/50), component failure (6/50), instability (6/50), and malalignment (2/50). The press-fit cementless stems were 80 to 160 mm in length and tightly contacted the endosteum of the metadiaphyseal areas. Four (9%) knees were re-revised for infection, zero for aseptic loosening. The average modified Hospital for Special Surgery knee score improved from 49 to 87. One patient (2%) reported thigh pain, and 1 reported leg pain. Metaphyseal cemented revision total knee components with press-fit cementless femoral and tibial stems were not associated with significant thigh and leg pain.     

Replacement of the aortic valve in patients under 50 years of age: long-term follow-up of the St. Jude Medical prosthesis

BACKGROUND: Aortic valve replacement in the young adult (aged 18 to 50 years) is a choice between a mechanical prosthesis with attendant lifelong anticoagulation or biological prostheses of varying types that may have limited life expectancy in this age group. METHODS: The Cardiac Surgical Research Foundation database was accessed to determine long-term outcomes in patients having aortic valve replacement with the St. Jude Medical Valve. This database has been privately maintained since the world's first St. Jude Medical (SJM) valve implant in 1977. Patients were contacted by questionnaire or by telephone if the survey was not returned. Follow-up was 93% complete. RESULTS: From October 1977 through October 1997, 271 patients less than 50 years of age had isolated aortic valve replacement. Follow-up was 1957 patient years. Thirty-day operative mortality was 1.1% with 18 late deaths, 4 of which were valve related. Ninety percent of survivor INR responses indicated a frequency of monthly INR checks or less. Valve-related events including percent per patient year and mortality related to these events included thromboembolism, 6 episodes (0.3% per patient year, no deaths); anticoagulant-related bleeding, 6 events (0.3% per patient year, 2 deaths); paravalvular leak, 6 events (0.3% per patient year, 2 deaths); valve thrombosis, 2 events (0.1% per patient year, no deaths); and endocarditis, 3 events (0.15% per patient year, no deaths). There was no incidence of structural valve failure. CONCLUSIONS: The SJM valve has a long record of excellent performance with durability lasting more than 20 years. The incidence of untoward events is low and death over time due to valve-related complications is low (4 of 271). The SJM valve has become our valve of choice for younger patients.