Small-diameter silicon nanowire surfaces.

Small-diameter (1 to 7 nanometers) silicon nanowires (SiNWs) were prepared, and their surfaces were removed of oxide and terminated with hydrogen by a hydrofluoric acid dip. Scanning tunneling microscopy (STM) of these SiNWs, performed both in air and in ultrahigh vacuum, revealed atomically resolved images that can be interpreted as hydrogen-terminated Si (111)-(1 x 1) and Si (001)-(1 x 1) surfaces corresponding to SiH3 on Si (111) and SiH2 on Si (001), respectively. These hydrogen-terminated SiNW surfaces seem to be more oxidation-resistant than regular silicon wafer surfaces, because atomically resolved STM images of SiNWs were obtained in air after several days' exposure to the ambient environment. Scanning tunneling spectroscopy measurements were performed on the oxide-removed SiNWs and were used to evaluate the electronic energy gaps. The energy gaps were found to increase with decreasing SiNW diameter from 1.1 electron volts for 7 nanometers to 3.5 electron volts for 1.3 nanometers, in agreement with previous theoretical predictions.

Limitations of craniocaudal thallium-201 and technetium-99m-sestamibi mammoscintigraphy.

UNLABELLED: Previous studies with 201Tl and 99mTc-sestamibi (MIBI) have used large field of view (LFOV) cameras not optimized for breast imaging. The purpose of this study was to compare these agents and to determine if a small field of view (SFOV) camera designed to minimize the camera-to-breast distance could improve tumor detection. METHODS: A 28-cm (SFOV) camera was fitted with slant-hole and diverging collimators to perform craniocaudal scintigraphy for direct comparison with mammography. Of the 46 patients studied, 20 had 201Tl imaging alone and 26 had combined 201Tl and MIBI imaging. LFOV (40 cm) breast and axillary images also were obtained. Visual and quantitative analyses of tumor uptake were performed. RESULTS: The SFOV camera with nonparallel collimation showed variable 201Tl and MIBI normal breast activity. This was partly due to significant scatter from cardiac and abdominal activity. Overall, 201Tl had a sensitivity of 53%, which was 67% for tumors > or = 1.5 cm and 20% for tumors < or = 1.5 cm. MIBI sensitivity was 90% (9/10) for lesions > or = 1.5 cm. Specificity was 93% for 201Tl and 83% for MIBI. There was no significant difference in 201Tl (1.76 +/- 0.55) and MIBI (1.82 +/- 0.95) tumor uptake ratios (p = 0.75). CONCLUSION: Technetium-99m-MIBI was more sensitive than 201Tl for imaging lesions > or = 1.5 cm. Craniocaudal positioning minimized the camera-to-breast distance but did not increase 201Tl detection of tumors < 1.5 cm and increased background breast activity due to scatter.

Complications of peripheral blood stem cell harvesting: review of 554 PBSC leukaphereses.

The collection of PBSC for transplantation requires repetitive leukapheresis, typically via central venous catheters (CVC). To assess the complications of this procedure, we reviewed 75 consecutive PBSC transplant candidates requiring 554 leukapheresis on a Haemonetics V50 Plus apheresis system. CVC occlusion necessitating thrombolytic therapy or cancellation of the procedure was the most commonly observed complication, occurring among 37 patients on 86 occasions (15.9% of CVC-aided collections). Thrombolytic therapy was successful in 85%. Of the patients, 16% experienced an infectious complication during the PBSC harvesting; chemotherapy mobilization significantly increased this risk, whereas growth factor mobilization was protective (p < 0.02). Hematologic complications including anemia (median postapheresis nadir hemoglobin 8.8 g/dl) and transient thrombocytopenia (median postapheresis nadir 64,000/microliters) required transfusional support among 30.7% and 14.7% of patients, respectively. The use of chemotherapy mobilization was correlated with increased need for support of both red cells and platelets (p < 0.001). Additional complications included catheter placement problems, symptomatic citrate-related hypocalcemia, transient hypotension, and machine-related malfunctions. Although the complications of the PBSC harvests were manageable, given their frequency the decision to pursue this form of hematopoietic rescue in preference to traditional operative bone marrow harvesting must address these risks.

Nonlactational breast infection.

Experiences with the treatment and results of treatment of 96 patients with acute or chronic periareolar abscesses are presented. A mammillary sinus or fistula was demonstrable in virtually every instance. The key to preventing recurrence is demonstrating and either removing or unroofing the sinus tract.

The Stamm gastrostomy: a sound procedure.

A review of 100 personal cases of open gastrostomy using a modified Stamm technique showed that the majority (82.7%) could be performed using local anesthesia with intravenous sedation. Only one patient suffered a wound infection, and there were no other technical complications. The use of a separate stab wound for the introduction of the tube and the routine use of antibiotic irrigation might have contributed to the reduction of wound complications. The overall mortality was 18 per cent, and all of the deaths were due to the patients underlying diseases. The Stamm procedure, which can be performed under local anesthesia without undue discomfort in the majority of patients, has a very low morbidity and no intrinsic mortality. It has a proper place in the armamentarium of nutritional support for these terminally ill patients.

The preoperative use of iodine solution in thyrotoxic patients prepared with propranolol. Is it necessary?

Despite the numerous reports documenting the safety and efficacy of the use of propranolol, a selective beta-adrenergic blocker, as the sole agent for preoperative preparation of a hyperthyroid patient, many surgeons continue to add a solution containing iodine to the treatment regimen. The rationale for the concomitant use of iodine solution and propranolol is that the iodine solution reduces the amount of propranolol required to make the patient symptomatically euthyroid and that iodine administration reduces the vascularity of the gland, thereby minimizing intraoperative blood loss. To ascertain the validity of these beliefs, we retrospectively reviewed our experience with 42 consecutive hyperthyroid patients who underwent subtotal thyroidectomy. These patients either received propranolol alone (20 patients) or propranolol with iodine solution (22 patients) for preoperative preparation. Comparison of the medication doses, estimated blood loss, and postoperative changes in hemoglobin and hemocrit using the Student's t-test, failed to demonstrate any significant difference between the two treatment protocols (P greater than 0.1). We conclude that the addition of iodine to propranolol for preoperative preparation of hyperthyroid patients does not result in any significant advantage over the use of propranolol alone.

The anatomy of the cephalic vein.

A cutdown on the cephalic vein for the insertion of a central venous catheter is simple and safe. The surgical anatomy of the cephalic vein is described.

Reinsertion of a gastrostomy tube using the Seldinger technique.

By using the Seldinger technique to recannulate a contracted fistula tract with a small catheter, a stenosed fistula tract can be progressively dilated. A new gastrostomy tube can then be inserted, thus avoiding a reoperation.

Tissue carcinoembryonic antigen levels in benign and malignant diseases of the breast.

The peroxidase-antiperoxidase histochemical method of staining for tissue carcinoembryonic antigen (CEA) was performed on 20 samples of malignant breast tissue, 20 samples of fibroadenomatous breast tissue, and 15 samples of breast tissue that variably contained minimal fibrosis (N = 7), ductal ectasia (N = 5), and sclerosing adenosis (N = 3; the fibrocystic changes of the breast). The intensity of staining was described to be either negative, weak, intermediate, or strong and was assigned a point value of 1, 2, 3, or 4, respectively. The following weighted average values of tissue CEA were obtained: carcinoma, 3.35 +/- 0.88; fibroadenomas, 2.85 +/- 0.67; fibrocystic changes, 2.13 +/- 0.52. Carcinomatous tissue is likely (55%) to display intense tissue staining, whereas fibrocystic disease (0%) or fibroadenoma (15%) are unlikely to exhibit such a reaction. The tissue CEA content between carcinoma and fibrocystic changes (P less than 0.01), carcinoma and fibroadenoma (P less than 0.01), and fibroadenoma and fibrocystic changes (P less than 0.05) are statistically significant.

DNA-cytophotometry of lymph node touch imprints in cutaneous T-cell lymphoma.

Scanning DNA-cytophotometry was performed on touch imprints of 26 lymph nodes (LN) obtained from 25 patients with cutaneous T-cell lymphoma (CTCL), stained by the Feulgen technique, and interpreted without knowledge of histopathologic diagnosis. Four patterns of DNA distribution were identified, but only histograms that demonstrated cells containing nuclei with more than 4C DNA content (hypertetraploidy) reliably distinguished LN involved with CTCL from LN with reactive changes; for example, dermatopathic lymphadenitis. An abnormal DNA histogram with evidence of hypertetraploidy was demonstrated in 9 of 12 LN showing histopathologic evidence of involvement compared with no abnormal histograms in 14 LN without histopathologic involvement. One LN that was diffusely involved with CTCL had a DNA distribution characteristic of a relatively high level of cell proliferation, but without definite hypertetraploidy. Cytogenetic studies on the blood of this patient, who had Sézary syndrome, demonstrated a clone of lymphocytes with a pseudodiploid karyotype without a related polyploid subline. The remaining two histopathologically involved LN had normal DNA histograms; these LN were only focally involved with CTCL. These observations indicate that DNA-cytophotometry correlates well with the histopathologic findings in LN diffusely involved with CTCL, but may be normal in LN with focal involvement or in those that contain cytogenetically abnormal cells with a near-diploid DNA content.

Significance of a curled central venous catheter tip.

A malpositioned central venous catheter can cause constant excessive pressure on one particular area of a central vein, thus leading to perforation and hydrothorax. The following is a case report of an iatrogenic hydrothorax caused by a malpositioned central venous catheter. The subtle sign of malposition is a slightly curled catheter tip.

Esophagogastric anastomosis.

Sixty-one consecutive patients underwent an end to side esophagogastric anastomosis combined with plication of the stomach around the distal part of the esophagus. No instance of free leakage occurred. Heartburn and regurgitation have been uncommon in this series of patients.

In extremis use of a Foley catheter in a cardiac stab wound.

A case is discussed of a patient who presented in extremis after a stab wound to the right ventricle. He underwent successful resuscitation using a Foley catheter both for hemostasis and for administration of resuscitation fluids. While not commonly employed in cardiac trauma management, this technique may permit increased salvage due to its simplicity and speed.

Carcinoembryonic antigen levels in colonic lesions.

We evaluated the likelihood of tissues to be positive for carcinoembryonic antigen and the intensity of carcinoembryonic antigen staining in specimens of villous adenomas, mixed polypoid villous adenomas, polypoid adenomas, and diverticulitis using the peroxidase-antiperoxidase technique. The presence of carcinoembryonic antigen could be demonstrated in all of the specimens; however, the intensity of staining varied. Villous adenomas were the most intensely stained, followed by mixed polypoid villous adenomas, polypoid adenomas, and diverticulitis. We conclude that (1) the intensity of tissue levels of carcinoembryonic antigen parallels the malignant potential of these different groups of lesions, (2) carcinoembryonic antigen intensity of mixed polypoid villous adenomas is more similar to villous adenomas than polypoid adenomas, and (3) the presence of carcinoembryonic antigen in diverticulitis is not a result of dysplasia.

Effects of intravenous versus intraatrial administration of doxorubicin on the function and structure of the heart.

To evaluate the relationship of toxicity of doxorubicin to route of administration, we studied 21 mongrel dogs which were randomly assigned to one of three groups: 1) a control group undergoing intraatrial indwelling catheter placement but no drug therapy; 2) an IV group receiving weekly doxorubicin by peripheral IV bolus administration; and 3) a catheter group receiving weekly doxorubicin through an indwelling intraatrial catheter. After 8 weeks all dogs were evaluated hemodynamically and then sacrificed. Sections of right ventricle were evaluated by light and electron microscopy. Although no hemodynamic alterations were found in any of the three groups, significant ultrastructural damage consistent with doxorubicin cardiac toxicity was demonstrable in four of the six evaluable catheter dogs receiving intraatrial doxorubicin, but in none of the other 13 dogs evaluated. This finding suggests that the intraatrial administration of doxorubicin may lead to cardiac toxicity at a lower cumulative dose than noted with peripheral IV administration.

Hepatic artery catheterization via the superior pancreaticoduodenal artery.

The superior pancreaticoduodenal artery is a continuation of the gastroduodenal artery. Besides being a good-sized artery, it is easily accessible. It is a reasonable vascular access for hepatic artery cannulation.

Radionuclide venography in subclavian vein thrombosis complicating parenteral nutrition.

Subclavian vein thrombosis and thrombophlebitis are common complications of subclavian vein catheterization for parenteral nutrition. We report two cases that demonstrate that radionuclide venography can be used to diagnose subclavian vein obstruction before classic clinical signs develop.