Understanding the tool influence function during sub-aperture belt-on-wheel glass polishing.

The tool influence function (TIF) during sub-aperture belt-on-wheel polishing has been evaluated as a function of various process conditions (belt use/wear, dwell time, displacement, belt velocity, and wheel modulus and diameter) on fused silica glass workpieces using C e O 2 polishing media. TIF spots are circular or elliptical in shape with a largely flat bottom character. The volumetric removal rate varies significantly with belt use (or wear), stabilizing after ∼15m i n of use. A modified Preston model, where the pressure dependence is adjusted using a different scaling of the wheel modulus (E w0.5), largely predicts the volumetric removal rate over the range of process conditions evaluated. The relatively high volumetric removal rate of 30-60m m 3/h using a fixed C e O 2-in-resin-host belt offers a rapid, and hence, more economical, initial polish of aspheric and freeform optics.

Kinesin is bound with high affinity to squid axon organelles that move to the plus-end of microtubules.

This paper addresses the question of whether microtubule-directed transport of vesicular organelles depends on the presence of a pool of cytosolic factors, including soluble motor proteins and accessory factors. Earlier studies with squid axon organelles (Schroer et al., 1988) suggested that the presence of cytosol induces a > 20-fold increase in the number of organelles moving per unit time on microtubules in vitro. These earlier studies, however, did not consider that cytosol might nonspecifically increase the numbers of moving organelles, i.e., by blocking adsorption of organelles to the coverglass. Here we report that treatment of the coverglass with casein, in the absence of cytosol, blocks adsorption of organelles to the coverglass and results in vigorous movement of vesicular organelles in the complete absence of soluble proteins. This technical improvement makes it possible, for the first time, to perform quantitative studies of organelle movement in the absence of cytosol. These new studies show that organelle movement activity (numbers of moving organelles/min/micron microtubule) of unextracted organelles is not increased by cytosol. Unextracted organelles move in single directions, approximately two thirds toward the plus-end and one third toward the minus-end of microtubules. Extraction of organelles with 600 mM KI completely inhibits minus-end, but not plus-end directed organelle movement. Upon addition of cytosol, minus-end directed movement of KI organelles is restored, while plus--end directed movement is unaffected. Biochemical studies indicate that KI-extracted organelles attach to microtubules in the presence of AMP-PNP and copurify with tightly bound kinesin. The bound kinesin is not extracted from organelles by 1 M KI, 1 M NaCl or carbonate (pH 11.3). These results suggest that kinesin is irreversibly bound to organelles that move to the plus-end of microtubules and that the presence of soluble kinesin and accessory factors is not required for movement of plus-end organelles in squid axons.

Synthesis and tumor-uptake study of phosphate esters of polyhedral hydroxyboranes.

The phosphorylations of B12H11OH2-,B12H10(OH)2-2-, and B20H17OH4-with POCl3 and (C6H5O)2POCl were investigated and the following derivatives were isolated: B12H11OPO3H3-,B12H11OPO3H2-2-,B12H11OPO(OC6H5)-2-2 minus, B12H11OPO(OC6H5)OH2 minus, b12h10(op2o6h2)2-4 minus, B12H10(OPO3H2)2-2 minus, B12Br10(OPO3H)2-4 minus, B12H10[O-PO(OC6H5)2]2-2 minus, B20H18OP2O6H2-4 minus, B20H18OPO3H2-3 minus. The B-O-P bonds proved very resistant to hydrolysis and the phosphates were administered in the for of Na+ salts at pH 7.2 to rats bearing subcutaneous glioma. The boron concentrations in tumors and the tumor/blood concentration ratios were compared with those of parent hydroxy derivatives. Except when the POH function was blocked by phenyl groups the phosphorylation invariably resulted in a greatly enhanced uptake of the borane into tumors and improved the tumor/blood boron ratio. The phopshate function appears to be one of the most effective handles for the incorporation of boron into brain tumors and the compounds show considerable promise for use in the neutron capture therapy of brain tumors.

A study of caloric restriction and cardiovascular aging in cynomolgus monkeys (Macaca fascicularis): a potential model for aging research.

Caloric restriction has been demonstrated to retard aging processes and extend maximal life span in rodents, and is currently being evaluated in several nonhuman primate trials. We initiated a study in 32 adult cynomolgus monkeys to evaluate the effect of caloric restriction on parameters contributing to atherosclerosis extent. Following pretrial determinations, at which time a baseline measure of ad libitum (ad lib) dietary intake was assessed, animals were randomized to an ad lib fed group (control) or a caloric restriction group (30% reduction from baseline intake). The animals are being evaluated for glycated proteins, insulin, glucose, insulin sensitivity measures, and specific measures of body fat composition by CT scans (e.g., intra-abdominal fat) over specified intervals. The results from the first year of observation demonstrate a significant diet effect on body weight, and specifically intra-abdominal fat. Further, insulin sensitivity has been significantly increased after 1 year of caloric restriction compared to the ad lib fed group. These studies indicate that caloric restriction has a marked effect on a pathologic fat depot, and this change is associated significantly with an improvement in peripheral tissue insulin sensitivity.

Expression of human activin C protein in insect larvae infected with a recombinant baculovirus.

In order to generate dimeric recombinant transforming growth factor-beta (TGF-beta) proteins, expensive eucaryotic cell systems, such as CHO cells, are usually used. An alternative represents the expression of such proteins in insects using a baculovirus expression system. In this study, recombinant human activin C protein was expressed in Noctuidae larvae. On SDS-PAGE, the expressed protein has a size of about 15 kD under reducing conditions and of about 20 kD under non-reducing conditions. This suggests that activin C is expressed as a dimer and disulfide bridges can be formed. Compared with expression in eucaryotic cell culture systems, expression in insect larvae presents a rapid and low cost method, without the need for expensive tissue culture scale-ups or special equipment.

Ultrasonographic diagnosis of varicoceles.

OBJECTIVE: To assess the ability of color duplex scrotal ultrasonography to detect subclinical varicoceles and confirm the diagnosis of clinical varicoceles. DESIGN: Physical examination, color duplex scrotal ultrasonography and internal spermatic venography was performed on 64 testicular units in 33 men. SETTING: Male fertility center. PATIENTS: Two hundred sixty-two consecutive men being evaluated for male factor infertility of whom 33 agreed to undergo venography. MAIN OUTCOME MEASURES: Ultrasonographic measurement of scrotal vein diameter of patients in the supine and upright position, before and during valsalva maneuver, and scrotal vein blood flow reversal with valsalva maneuver was compared with the findings of varicocele by physical examination and venography. RESULTS: The best predictor of a varicocele was internal spermatic vein diameter, and the best overall performance of ultrasonography was achieved with the patient at rest in the supine position. The best cutoff point for venous diameter for a clinical varicocele was 3.6 mm and 2.7 mm for a subclinical varicocele, but the overall accuracy was only 63%. CONCLUSIONS: Confirmatory studies are needed to support the ultrasonographic diagnosis of varicoceles before considering surgical repair.

Imaging approach to staging of renal cell carcinoma.

Current imaging techniques, especially CT and MR imaging, make accurate preoperative staging of renal cell carcinoma possible. Because surgery provides the only effective therapy and because survival depends on local and distant extent, precise staging is critical for preoperative planning and prognosis. This article reviews the advantages, limitations, accuracy, and pitfalls of each of the imaging approaches to staging renal cell carcinoma, concentrating on CT and MR imaging. This information then is summarized in a suggested overall approach to staging renal cell carcinoma.

The role of imaging in staging renal adenocarcinoma.

Numerous surgical options are available to physicians treating patients with renal adenocarcinoma. In the current clinical setting, imaging plays a key role in determining which options are selected. Newer imaging techniques such as helical CT with CT angiography, MRI, and ultrasound (US) have improved staging capabilities in this patient population. However, to approach staging accuracies recently reported, attention must be paid to proper imaging parameters. This article describes the strengths, limitations, and proper techniques used for staging renal adenocarcinoma with CT, MRI, and US.

CT diagnosis of acute flank pain from urolithiasis.

The use of noncontrast helical CT (NHCT) to assess patients with acute flank pain and hematuria for potential urinary tract stone disease was first reported in 1995. After several years of experience with the technique, sensitivity and specificity of NHCT has proven to be better than intravenous urography for evaluating ureteral stones. NHCT imaging findings for urinary calculi and the differential diagnosis are discussed in this article. Various extraurinary diseases found while using NHCT in searching for stone disease are addressed and illustrated. As experience with the use of NHCT has increased, clinicians have broadened the indications for this technique, which has a lower charge than standard CT, beyond the specific evaluation of urinary colic. This indication creep has increased the number of NHCT examinations ordered. It has also reduced the rate of stone positivity and increased the diagnostic yield for extraurinary disease.

MRI findings of sciatic endometriosis.

Endometriosis is a rare cause of sciatic mononeuropathy. We report a woman with cyclic, menstruation-related hip pain associated with right leg weakness and sensory loss. Examination and electrodiagnostic studies suggested sciatic nerve dysfunction. Magnetic resonance imaging (MRI) revealed abnormal signal consistent with endometriotic tissue in the region of the right sciatic nerve. The abnormal signal partially regressed after treatment of the endometriosis. This case further illustrates the utility of MRI in the assessment of rare pelvic disorders.

Computed tomography evaluation of colorectal carcinoma.

Knowledge of the extent of primary colorectal carcinoma at initial diagnosis is critical for proper management of disease. Currently, CT does not have a role in screening for colorectal carcinoma, though promising work on virtual colonoscopy is on the horizon. In patients with proven colorectal carcinoma, accurate prospective noninvasive assessment can identify those who may benefit from preoperative local radiotherapy, hepatic resection or cryoablation, or intra-arterial chemotherapy. CT should be considered complementary to the clinical assessment of colorectal carcinoma and to other modalities, such as barium enema, endorectal ultrasonography, MRI, and immunoscintigraphy. Although limited in evaluation of the primary tumor and local spread, CT has proven useful in assessing patients thought to harbor extensive local or metastatic disease. CT is generally the modality of choice for imaging the postoperative patient. The cross-sectional display of CT clearly depicts the operative bed, particularly after abdominoperineal resection. Baseline examinations should be obtained 2 to 4 months after surgery, with follow-up examinations every 6 to 9 months for 2 years, and yearly studies thereafter. CT-guided biopsies should be performed when findings suggest recurrent carcinoma.

Structure of an electron transfer complex. II. Chemical modification of carboxyl groups of cytochrome c peroxidase in presence and absence of cytochrome c.

Cytochrome c peroxidase forms an electron transfer complex with cytochrome c. The complex is governed by ionic bonds between side chain amino groups of cytochrome c and carboxyl groups of peroxidase. To localize the binding site for cytochrome c on the peroxidase, we have used the method of differential chemical modification. By this method the chemical reactivity of carboxyl groups (toward carbodiimide/aminoethane sulfonate) was compared in free and in complexed peroxidase. When ferricytochrome c was bound to cytochrome c peroxidase, acidic residues 33, 34, 35, 37, 221, 224, and 1 to 3 carboxyls at the C terminus became less reactive by a factor of approximately 4, relative to the remaining 39 carboxylates of peroxidase. Of the less reactive residues those in the 30-40 region and the 221/224 pair are on opposite sides of the surface area which contains the heme propionates. We, therefore, propose that the binding site for cytochrome c on cytochrome c peroxidase spans the area where one heme edge comes close to the molecular surface. The results are in very good agreement with chemical cross-linking studies (Waldmeyer, B., and Bosshard, H.R. (1985) J. Biol. Chem. 260, 5184-5190); they also support a hypothetical model predicted on the basis of the known crystal structures of cytochrome c and peroxidase (Poulos, T.L., and Kraut, J. (1980) J. Biol. Chem. 255, 10322-10330).

Pelvic lipomatosis with ureteral encasement and recurrent thrombophlebitis.

Multiple complications occurred in a patient with severe pelvic lipomatosis and recurrent superficial thrombophlebitis. Distal ureteral and rectal encasement by lipomatous infiltration caused obstructive uropathy and rectal deformity without substantial compromise of renal or gastrointestinal function. Clinical evidence suggests an association between pelvic lipomatosis and recurrent superficial thrombophlebitis.

MR appearance of sternal hyperostosis.

Sternal hyperostosis is characterized by prominent new bone formation and fibrosis with less pronounced areas of granulation tissue and round cell infiltration. In previously reported cases the process involved not only the sternum but adjacent bony areas as well. Depending upon the extent of disease, acquiring biopsy material for histologic analysis can be difficult. We report a case of sternal hyperostosis involving the sternum exclusively and extensively. Magnetic resonance imaging was useful in directing biopsy for optimal histologic yield. This unusual case of sternal hyperostosis is believed to be the result of an inflammatory process.

Directional electron transfer in ruthenium-modified horse heart cytochrome c.

Cytochrome c can be modified by [(NH3)5RuII/III-] specifically at the imidazole moiety of histidine 33, and we have recently discussed the thermodynamics and kinetics of electron transfer within this modified protein. X-ray crystal structures of the oxidized and reduced forms of tuna cytochrome c indicate that the separation between the haem group of cytochrome c and the ruthenium label is 12-16 A. Internal electron transfer from the [(NH3)5RuII-] centre to the Fe(III) haem centre occurs with a rate constant k congruent to 53 s-1 (25 degrees C) (delta H = 3.5 kcal mol-1, delta S = -39 EU), as measured by pulse radiolysis. The measured unimolecular rate constant, k congruent to 53 s-1, is on the same timescale as a number of conformational changes that occur within the cytochrome c molecule. These results raise the question of whether electron transfer or protein conformational change is the rate limiting step in this process. We describe here an experiment that probes this intramolecular electron transfer step further. It involves reversing the direction of electron transfer by changing the redox potential of the ruthenium label. Electron transfer in the new ruthenium-cytochrome c derivative described here is from haem(II) to the Ru(III) label, whereas in (NH3)5Ru-cytochrome c the electron transfer is from Ru(II) to haem(III). Intramolecular electron transfer from haem(II) to Ru(III) in the new ruthenium-cytochrome c described here proceeds much slower (greater than 10(5) times) than the electron transfer from Ru(II) to haem(III) in the (NH3)5Ru-cytochrome c. We therefore conclude that electron transfer in cytochrome c is directional, with the protein envelope presumably involved in this directionality.

Magnetic resonance imaging of pediatric hip disease.

The efficacy of magnetic resonance imaging (MRI) in the assessment of pediatric hip disease was tested by scanning the hips of 24 children (30 scans). Twelve patients with Legg-Calvé-Perthes disease (17 hips) showed characteristic areas of low-intensity signal representative of necrotic areas of the capital epiphysis. Abnormal scans were also obtained on patients with transient synovitis, avascular necrosis secondary to steroids, epiphyseal dysplasia, and multiple osteochondromatosis. MRI accurately shows articular cartilage, femoral head shape, quality of containment, and areas of necrosis in pediatric hips. The extent of involvement and revascularization can be identified in Legg-Calvé-Perthes disease.

Staging of renal adenocarcinoma: role of various imaging procedures.

Since the only successful curative treatment of renal adenocarcinoma is surgery, accurate radiologic information is crucial during initial tumor staging for optimal operative planning. Accurate radiologic staging can be achieved by use of proper imaging techniques, usually a combination of contrast-enhanced CT or multiplanar MR imaging with fast scanning techniques. These techniques permit the demonstration of regional lymph nodes, vascular extension, and distant metastases. Sonography and inferior venacavography are used occasionally to supplement the information obtained from CT or MR imaging. We review the principles of staging of renal adenocarcinoma, emphasizing the strengths and weaknesses of each imaging technique.

Postoperative computed tomographic evaluation of congenital hip dislocation.

The use of computed tomography (CT) in the postoperative evaluation of 19 congenitally dislocated hips is presented so that appropriate indications for reduction can be determined and radiologic criteria can be defined for judging whether reduction is satisfactory. The radiologic technique is presented. CT is an accurate and cost-effective modality that is capable of demonstrating subtle changes in femoral head position.

Evaluation of PACS in ultrasonography.

We review our experience with a picture archiving and communication system to replace film in the ultrasound section of a clinical radiology department. The system includes three ultrasound units connected by a fiberoptic network via acquisition nodes to a central data management system, workstation, and optical jukebox. The system handles 80% of sonographic studies in the department. Image production, interpretation, storage, and retrieval are evaluated. Despite limitations, a picture archiving and communication system can be integrated into a functioning ultrasound section of an active radiology department with minimal disruption and promising results.