A comparison of resolution of DNA fragments between agarose gel and capillary zone electrophoresis in agarose solutions

The resolving power of capillary zone electrophoresis (CZE) is compared to that of gel electrophoresis (GE) under similar conditions (agarose, similar length of DNA fragments, identical buffer) but with differences in temperature and field strength. The comparison is based on the time required to reach a desired degree of resolution by each of the two methods. A resolution parameter is developed which is equally applicable to CZE, with relatively diffuse initial conditions in the absence of stacking and measurements expressed in terms of time, and to GE, in which measurements are expressed in terms of spatial parameters. The resolution time in CZE using agarose solutions at 40 degrees C was found to be greater by at least one order of magnitude than that in GE using agarose gels. Thus, the increased migration velocity due to high field strength in CZE substantially outweighs the lower dispersion in GE.

Calcium tracer kinetics show decreased irreversible flow to bone in glucocorticoid treated patients

Osteopenia resulting from pharmacologic doses of glucocorticoids is well known. Previously, there has been no satisfactory quantitative model describing the kinetics of calcium flow in subjects on chronic steroid use. A mathematical model of calcium isotope interaction with bone is described and applied to determine an estimate of kinetic parameters characterizing these changes. Calcium tracer dilution kinetics after a bolus injection of 42Ca were measured in 14 subjects with juvenile dermatomyositis, 6 on prednisone regimens and 8 on treatment regimens without prednisone. Irreversible tracer loss from plasma bone is found to be significantly reduced (P = 0.043) in the glucocorticoid-treated patients compared with patients on nonsteroid regimens. Reversible flow to bone is noted to be similar in the two groups. These results suggest a direct effect of glucocorticoids on osteoblast function.

Expression of scatter factor in human bladder carcinoma

BACKGROUND

Scatter factor (SF) is a protein secreted by stromal (supporting) cells that induces disruption of intercellular junctions and stimulates motility and invasiveness of carcinoma cells. SF is also a potent inducer of angiogenesis (new blood vessel formation), a process required for tumor growth and dissemination. Invasion and angiogenesis are characteristics of biologically aggressive tumors, suggesting that the accumulation of SF within tumors might promote progression to a more malignant phenotype.

PURPOSE

This study was designed to determine if SF is overexpressed in carcinoma of the bladder and to evaluate the potential mechanisms that might account for such overproduction.

METHODS

We measured the SF content in urine from 20 patients with carcinoma of the bladder and various control groups. We also measured expression of SF in bladder tumor extracts, histologic sections of tumors, and cell culture models, using a variety of techniques, including enzyme-linked immunosorbent assays, immunohistochemistry, and Western and Northern blot analyses. Statistical comparisons were performed using two-tailed t tests.

RESULTS

Urinary SF content was found to be significantly elevated in patients with bladder carcinoma as compared with normal control subjects (P < .001), patients with benign prostatic hypertrophy (P = .0055), and patients with prostate carcinoma, another genitourinary malignancy (P = .002). Extracts of bladder cancers, especially those from high-grade, invasive tumors, contained very high levels of SF. Both SF and its proto-oncogene (c-met)-encoded receptor were detected in bladder carcinoma tissue sections by immunostaining. Three different bladder carcinoma cell lines produced no detectable SF but produced very high titers of a high-molecular-weight (> 30 kd), heat-sensitive protein that stimulates SF production by stromal cell types. High titers of a similar SF-inducing activity were detected in vivo, in bladder carcinoma extracts, and in the urine of patients with bladder carcinoma.

CONCLUSIONS

Our results suggest that SF is overproduced in bladder carcinomas and accumulates within the tumor and in the urine. Overproduction of SF may result from an abnormal urothelial-stromal interaction in which dysplastic or carcinomatous urothelium secretes factors that stimulate SF expression by bladder wall stromal cells.

IMPLICATION

Quantitation of SF in the urine and tumor deserves further study as a possible marker of urothelial malignancy.

Model of human transitional cell carcinoma: tumor xenografts in upper urinary tract of nude rat

An in vivo model for the study of human transitional cell carcinoma (TCC) in the urinary tract is desirable. Orthotopic xenografts are useful in order to approximate better the behavior of human tumor cells in situ. Prior models have been described in the urinary bladder of the nude mouse and rat. We have developed the first model of implantation of human TCC in the upper urinary tract of an experimental animal. The kidneys of homozygous nude rats 4 weeks of age were inoculated with 1-5 x 10(6) cells of the RT4 well-differentiated papillary human TCC line through bilateral flank incisions, with transparenchymal injection of tumor cells into either the collecting system (renal pelvis) or the parenchyma. The overall implantation rate was 92% (54/59 kidneys). However, implantation into the collecting system occurred in only 45% (18/45) of the group. Ligation of the ureter prior to inoculation to produce urine stasis improved the mucosal implantation rate. Despite suspect urine cytology findings in the renal pelvis injection group, no distal seeding of the urinary tract was seen. Intraparenchymal tumor growth was less differentiated and had a higher fraction of mitotic cells than mucosal tumors. Vascular and lymphatic invasion were commonly seen; however, distant metastasis was not observed. This model will prove useful in determining the role of seeding in recurrent disease and in developing less invasive modalities for the treatment of upper tract TCC.

A non-Markovian model for calcium kinetics in the body

We present a new generalized compartmental model for calcium kinetics as measured by tracer concentration in blood plasma. The parameter measuring incorporation of calcium in bone discriminates between different levels of physical development in female teenagers and between teenagers and adults.

Optimization of magnetization transfer experiments for kinetic rate measurements

A framework is developed for optimizing magnetization transfer experiments for measuring first-order rate constants of a two-component exchange network. In the analysis the spin-lattice relaxation time of the nonsaturated resonance is assumed to be known. However, we demonstrate that our work can also be applied to cases in which the spin-lattice relaxation time falls within a physiologically reasonable range for this parameter. We provide an algorithm for the parameters permitting the experimenter to optimize the selection of measurement times in order to control the error in a worst-case scenario. In addition, we compare the performance of the time-dependent saturation experiment with an inversion experiment in this framework, finding that the former always leads to a more effective design.

Effects of noncrystallographic symmetry on the epsilon 1 relationship. I. Bicentric arrangements in P1

An exact Fourier representation of the probability for the epsilon 1 relationship is derived, which takes into account the presence of noncrystallographic centrosymmetry in the asymmetic unit of the space group P1. Illustrative examples show that the main effect of noncrystallographic symmetry is to decrease the probability that E2h is positive, as compared to the corresponding probability in the absence of such symmetry. The effect appears to be more pronounced in the equal-atom case than it is for a structure having a heterogeneous atomic composition.

Exact conditional distribution of a three-phase invariant in space group P1. IV. Further improvements of Cochran-like approximations

A new approximate method of computing the conditional probability density function (c.p.d.f.) of a three-phase invariant is investigated, the results being compared to accurate calculations [Shmueli, Rabinovich & Weiss (1989). Acta Cryst. A45, 361-367]. A direct dependence on N, the number of atoms in the unit cell, is incorporated into the new approximation and its performance in the equal-atom case appears to be excellent over a large range of N values. The polynomial approximation of the recently published method [Posner, Shmueli & Weiss (1993). Acta Cryst. A49, 260-265] has been improved in both accuracy and range.

Generalized theory of the kinetics of tracers in biological systems

Most theoretical analyses of tracer kinetics in capillaries contain an implicit assumption that the tissues to which they are connected have homogeneous material properties. The microscopic description of the exchange of tracer molecules and tissues is then modeled in terms of first-order kinetics. We consider a class of more general models allowing us to assess the robustness of simplifying assumptions made above. It is shown that when amorphous properties are important the kinetics of the system may differ considerably from those predicted by standard theories.

Cytoreductive surgery prior to interleukin-2-based therapy in patients with metastatic renal cell carcinoma

From May 1985 to December 1990, 93 patients with the clinical diagnosis of metastatic renal cell carcinoma and their primary tumor in place were evaluated for cytoreductive surgery as preparation for systemic therapy with regimens based on interleukin-2. These patients had typical sites of metastatic disease and manifestations of paraneoplastic syndromes. Patients underwent removal of the primary tumor, as well as debulking when this could be performed safely. Thirty-two percent of patients (30/93) had a second surgical resection in addition to their nephrectomy, frequently because of the large size of the primary tumor and its invasion of adjacent structures. Thirteen percent of patients (12/93) experienced postoperative complications. There were no perioperative mortalities. Forty percent of patients (37/93) who underwent nephrectomy could not be treated with immunotherapy, usually because of progression of disease. A preoperative ECOG status greater than or equal to 2 was the only significant risk factor associated with failure to undergo immunotherapy (P = 0.043). The response rate to immunotherapy in the 56 patients receiving interleukin-2 was 27 percent (4 CR, 11 PR).

Exact conditional distribution of a three-phase invariant in the space group P1. III. Construction of an improved Cochran-like approximation

An exact representation of the accurately computable conditional probability density function (c.p.d.f.) of the three-phase invariant for the space group P1 was developed in paper I of this series [Shmueli, Rabinovich & Weiss (1989). Acta Cryst. A45, 361-367]. The computation of this function is too time-consuming for it to be of practical value. It is therefore desirable to find simple approximations based on the exact result that may be more accurate than the familiar Cochran approximation or its extensions. One such approximation, presented here, has the same functional form as the Cochran approximation but with a modified parameter in place of that appearing in Cochran's distribution. Some of the numerical procedures used in the estimation of this modified parameter are also discussed.

Numerical method for studying the detectability of inclusions hidden in optically turbid tissue

We introduce an efficient numerical method for studying the detectability of absorptive inclusions in a multiple-scattering optical medium. Use of the method is demonstrated by the forward calculation of integrated and time-gated photon intensities. Schemes for positioning the light source above an inclusion and otherwise determining the location of a hidden object, involving either reflected or transmitted reemissions, are discussed as examples. They are investigated for several illustrative models, and images are calculated as a function of the size and shape of the inclusion.

The natural history of renal lesions in von Hippel-Lindau disease: a serial CT study in 28 patients

OBJECTIVE

Von Hippel-Lindau disease is a multisystem disorder predisposing to renal cysts and cancer. The growth and development of these renal lesions have not been documented previously. We reviewed serial CT scans to determine the rates and patterns of growth of renal lesions associated with von Hippel-Lindau disease.

SUBJECTS AND METHODS

Twenty-eight patients with von Hippel-Lindau disease and renal involvement, including the spectrum from simple cysts to solid masses, had follow-up examinations for at least 1 year (mean, 2.4 years; range, 1-12 years) with serial contrast-enhanced abdominal CT. Renal lesions were measured and characterized. Surgical correlation was available in 12 patients.

RESULTS

Two hundred twenty-eight lesions (eight lesions per patient) were detected. On the basis of their CT appearance, 168 lesions (74%) were classified as cysts, 18 (8%) as cysts with solid components, and 42 (18%) as solid masses. Among 12 patients with pathologic confirmation, the solid components of cystic lesions and solid lesions almost always contained renal carcinoma. The majority of cysts remained the same size (71%) or enlarged (20%); 9% became smaller or entirely involuted during the follow-up period. Although it is generally presumed that renal cysts are precursors to cancers, the transformation of a simple cyst to a solid lesion was observed in only two patients. Among the 42 solid lesions, all but two enlarged with time, with a mean doubling time of 10 months.

CONCLUSION

The renal lesions associated with von Hippel-Lindau disease exhibited wide differences in growth. The majority of renal cysts grew slowly but some involuted. Transition to solid renal cancer was rare among cysts. Complex cystic and solid lesions contained neoplastic tissue that uniformly enlarged. These data may be used to help predict the progression of renal lesions in von Hippel-Lindau disease.