Ultrafast optical multidimensional spectroscopy without interferometry.

We present here the details of a phase retrieval technique that provides access to multidimensional modalities that are not currently available using existing interferometric techniques. The development of multidimensional optical spectroscopy has facilitated significant insights into electronic processes in physics, chemistry, and biology. The versatility and number of available techniques are, however, significantly limited by the requirement that the detection be interferometric. Many of these techniques are closely related to the vast range of multidimensional NMR spectroscopies, which revolutionized analytical chemistry more than 30 years ago. We focus here on the specific case of two-color multidimensional spectroscopy (analogous to heteronuclear NMR) and discuss the details of an iterative algorithm that recovers the relative phase relationships required to perform the Fourier transformation and find the unique solution for the 2D spectrum. A detailed guide is provided that describes the practical implementation of such algorithms. The effectiveness and accuracy of the phase retrieval process are assessed for simulated one- and two-color experiments. It is also compared with one-color experimental data for which the target phase information has been obtained independently by interferometry. In all the cases, the present algorithm yields results that compare well with the solutions obtained by other means. There are, however, some limitations and potential pitfalls that are identified and discussed. We conclude with a discussion of the potential applications and further advances that may be possible by adopting iterative phase retrieval algorithms of the type discussed here.

Highly purified CD44+ prostate cancer cells from xenograft human tumors are enriched in tumorigenic and metastatic progenitor cells.

CD44 is a multifunctional protein involved in cell adhesion and signaling. The role of CD44 in prostate cancer (PCa) development and progression is controversial with studies showing both tumor-promoting and tumor-inhibiting effects. Most of these studies have used bulk-cultured PCa cells or PCa tissues to carry out correlative or overexpression experiments. The key experiment using prospectively purified cells has not been carried out. Here we use FACS to obtain homogeneous CD44(+) and CD44(-) tumor cell populations from multiple PCa cell cultures as well as four xenograft tumors to compare their in vitro and in vivo tumor-associated properties. Our results reveal that the CD44(+) PCa cells are more proliferative, clonogenic, tumorigenic, and metastatic than the isogenic CD44(-) PCa cells. Subsequent molecular studies demonstrate that the CD44(+) PCa cells possess certain intrinsic properties of progenitor cells. First, BrdU pulse-chase experiments reveal that CD44(+) cells colocalize with a population of intermediate label-retaining cells. Second, CD44(+) PCa cells express higher mRNA levels of several 'stemness' genes including Oct-3/4, Bmi, beta-catenin, and SMO. Third, CD44(+) PCa cells can generate CD44(-) cells in vitro and in vivo. Fourth, CD44(+) PCa cells, which are AR(-), can differentiate into AR(+) tumor cells. Finally, a very small percentage of CD44(+) PCa cells appear to undergo asymmetric cell division in clonal analyses. Altogether, our results suggest that the CD44(+) PCa cell population is enriched in tumorigenic and metastatic progenitor cells.

Postnatal development of nitric oxide synthase expression in the mouse superior colliculus.

Since nitric oxide has a role in the refinement of the retinal projection to the superior colliculus (SC), we studied the onset of neuronal nitric oxide synthase (nNOS) expression in the mouse SC in order to compare its development with that of the refinement process. Sections from animals at ages P1, P5, P8, P11, P15, and P21 and adults were examined with nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry or immunocytochemistry using an antibody directed against nNOS. At all ages there was a wedge of labeled neurons in the dorsolateral periaqueductal gray extending into the deep layers of the SC. At P1 there was also a single superficial band of labeled neurons within the region that will become the intermediate gray layer (IGL). By P5, labeled neurons were also seen in what will become the superficial gray layer. There was a ventral to dorsal progression in nNOS expression with substantial changes in the numbers of labeled neurons in the different laminae between P5 and adulthood. The number of labeled neurons in the IGL peaked at P15, whereas in the superficial layers the numbers continued to increase through P21 and then declined in adults. At all ages these neurons represented a variety of morphological cell types. The onset of nNOS expression in the different laminae is earlier than has been reported in studies using NADPHd as a marker for nNOS. The temporal and spatial patterns of nNOS expression reported here match more closely the time course of pathway refinement in the SC, providing additional evidence for the involvement of nitric oxide in this process.

Variables associated with adolescent alcohol use: a multiethnic comparison.

The authors examined the influence of sociodemographic variables on the frequency and intensity of alcohol use among a nationally representative sample of Black, Hispanic, and White adolescents who had participated in the 1991 National Household Survey on Drug Abuse (U.S. Department of Health and Human Services, 1993). The sample consisted of 8,756 U.S. adolescents aged 12 to 18 years. The authors found that (a) approximately 19% of the respondents had used alcohol in the last 30 days: (b) among the respondents who had used alcohol, 21% had consumed 1 or more drinks per drinking episode; and (c) there were important similarities as well as important differences in variables that promoted alcohol use among Black. Hispanic, and White adolescents.

Peer review and risk management.

As physicians and other health-care providers are experiencing an increased number of lawsuits, external pressures also are being exerted by various third-party payers and peer review organizations. An overview of some of the problems that may arise and methods for responding is presented. Knowledge of the processes involved by peer groups will help in risk management concerns as well. A new approach to quality assurance by the federal government is also described, the Health Care Quality Improvement Initiative.

The application of preoperative radiation therapy for unresectable malignancies.

Preoperative radiation therapy is one of the major indications for the use of ionizing radiation in the treatment of malignant disease. The preoperative application of radiation treatment is given with the intention of reducing the size of bulky cancers, thus converting unresectable tumors into resectable ones. Other benefits are reduction in the risk of locoregional recurrence and in the risk of blood-borne dissemination of malignant cells promoted during surgical resection.This paper presents and discusses three cases of unresectable intrapelvic tumors initially treated by radiation therapy with the primary goal of palliation. These three cases included rectal, cecal, and uterine carcinoma. In each case, a preoperative radiation dose of 4500 to 5000 cGy was delivered. Evaluations during and after the completion of the radiation treatments revealed that the tumor responded remarkably well to the treatment, which encouraged the surgical intervention; at surgery, minimal tumor was found. These three patients are alive to date without apparent evidence of disease.

Partial inflow occlusion: a neglected technique for treating troublesome aortic leaks.

Most cardiac surgeons occasionally encounter troublesome bleeding from an ascending aortic site and are aware of the potential difficulties associated with repairing this complication. Partial inflow occlusion, as described below, is a simple method of depressurizing the aorta to facilitate suture placement after cardiopulmonary bypass.

Polypropylene suture--is it safe?

Polypropylene suture has steadily gained popularity for use in vascular and cardiac surgical procedures because of its long-term tensile strength and minimal tissue trauma. However, recently some questions have arisen concerning its safety. We recently had two cases of polypropylene fracture, one occurring early and the other late after operation. Comparison and collation of these two cases with other reports leads to the conclusion that polypropylene suture is safe in most situations, but care must be taken to avoid instrumentation trauma and kinking stresses at knots, which probably explain most of the reported cases of polypropylene failure. In addition, polypropylene probably should not be used in graft-to-graft anastomoses in which the continual sawing stresses of two rigid structures appears to lead to an excessive incidence of late suture fracture with resultant false aneurysm formation.

Proximal shunt dissection: a potential problem in carotid endarterectomy.

The use of a shunt routinely, selectively, or not at all in performing carotid endarterectomy is a controversial and thus far unsettled dilemma. We have routinely used a shunt because it allows the operation to be done meticulously and without a sense of urgency. However, we recently encountered a case in which proximal subintimal dissection occurred secondary to shunt insertion, which resulted in a postoperative neurologic deficit. We present the case, with a discussion of the probable cause of dissection and its future prevention.

Sequential bypass grafting for salvage of lower extremities.

Since 1978, 12 patients at our institution have had distal sequential bypass grafting for limb salvage with either polytetrafluoroethylene (PTFE) or reversed saphenous vein and anastomoses to two different distal vessels. Seven patients had had previous vascular operations. One patient died of a stoke in the early postoperative period; a second patient, who was lost to follow-up several months after operation, was presumed to have died. Follow-up is otherwise complete (range seven to 48 months), without early or late limb loss. Results are encouraging and suggest that the sequential anastomotic technique may offer improved results in appropriate limb salvage cases with poor distal runoff.

Use of cardiopulmonary bypass for thrombectomy in acute superior vena cava syndrome.

An increasing incidence of nonmalignant, indwelling catheter cases has been reported in relation to superior vena cava syndrome. Such cases may be life-threatening, with rapid development of facial and neck edema and the production of respiratory distress. This is the first reported case of atrial and superior vena caval thrombectomy requiring cardiopulmonary bypass; it is only the second case reported in which operative thrombectomy has been used. Because of the problems associated with an increase in the use of indwelling venous catheters and the satisfactory results we obtained in this case, such an aggressive form of treatment for acute, benign superior vena cava syndrome may be used more frequently in the future.

Coarctation of the abdominal aorta.

Coarctation of the abdominal aorta represents an unusual but surgically treatable form of hypertension. The cause is somewhat controversial but generally can be traced to congenital or acquired origins. A case is presented in which the anomaly appears to be congenital. The variability in anatomy and subsequent treatment are discussed along with appropriate evaluation of the problem.

Myocardial fibroma or fibrous hamartoma.

Early interest in myocardial tumors was directed primarily at their pathology. Today, however, interest must be in early diagnosis and planned operation utilizing cardiopulmonary bypass since such tumours, both benign and malignant, are potentially lethal due to their location and since most are resectable. The case of a patient with myocardial fibroma presented here offers an expanded pathological picture: the tumor contained fibrous tissue, cardiac muscle, vascular elements, adipose tissue, and smooth muscle. Smooth muscle has not been previously reported. A review of the literature reveals disagreement and confusion over proper nomenclature for the entity. Perhaps its varied histological presentation is better described as fibrous hamartoma than fibroma.