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Biomedical subjects

G H Weiss

Publications and source records attributed to G H Weiss.

At least 19 recordsLinked to original sources
PubMed1992

Changes in urinary magnesium, citrate, and oxalate levels due to cola consumption.

The serum concentration and urinary excretion of four potential stone constituents: calcium, oxalate, phosphate, and uric acid; and of two potential inhibitors of urinary stone formation, citrate and magnesium, were studied before and during ingestion of a carbonated cola beverage. Four participants, after baseline serum determinations, abstained for forty-eight hours from cola consumption and then attempted to drink 3 quarts per day of cola in the following forty-eight hours. One participant failed to drink more than two quarts per day of cola. In all 4 participants twenty-four-hour urinary excretion of magnesium decreased by an average of 2.6 mg. In the 3 participants who succeeded in drinking 3 quarts of cola per day, twenty-four-hour urinary excretion of oxalate increased an average of 8.3 mg and excretion of citrate decreased an average of 122 mg. These results demonstrate changes in urine constituents which could contribute to enhanced kidney stone formation in patients who drink large quantities of cola-flavored carbonated beverages.

Adult↗
PubMed1992

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.

Adult↗
PubMed1991

Exact random-walk models in crystallographic statistics. VI. P.D.F.'s of magnitude of [E] for all plane groups and most space groups.

An exact calculation of the probability density function (p.d.f.) of magnitude of [E], the magnitude of the normalized structure factor, can be developed in terms of Fourier and Fourier-Bessel series whose coefficients can be expressed in terms of the characteristic function. This article provides the formulae for atomic contributions to such characteristic functions. The results presented in this study are applicable to all the plane groups and to 206 three dimensional space groups. Only the space groups isomorphous to the cubic point groups 432, 43m and m3m were omitted due to the complexity of the resulting expressions and the small deviations of the corresponding densities from the central-limit-theorem approximation, which have been observed in simulations for extreme atomic heterogeneities. Representative derivations illustrating the problems and techniques of their solution are provided. All the theoretical results have been computed numerically and compared with simulated distributions. Some results of these computations are illustrated in the accompanying paper, Part VII of this series [Rabinovich, Shmueli, Stein, Shashua & Weiss (1991). Acta Cryst. A47, 336-340].

Fourier Analysis↗
PubMed1991

Exact random-walk models in crystallographic statistics. VII. An all-space-group study of the effects of atomic heterogeneity on the P.D.F.'s of magnitude of [E].

Exact expressions have been found for the probability density functions (p.d.f.'s) of the magnitude of the normalized structure factor for all the two-dimensional and most three-dimensional space groups [Part VI: Rabinovich, Shmueli, Stein, Shashua & Weiss (1991). Acta Cryst. A47, 328-335]. The results of that investigation are used in the present article to examine some effects of atomic heterogeneity, in the various space-group symmetries, on the p.d.f.'s. Some typical comparisons are made between p.d.f.'s based on the central limit theorem and p.d.f.'s computed from exact formulae. In addition, the exact results are compared to histograms of simulated values of magnitude of [E]. It is found that the p.d.f.'s for some space groups are influenced rather strongly by the presence of outstandingly heavy scatters, but they are quite insensitive to the presence of such scatterers in other space groups. The often made general statement 'The presence of outstandingly heavy scatterers may invalidate the indications of Wilson's statistics' is made more precise here, insofar as it depends on the particular space group.

Fourier Analysis↗
PubMed1991

Molecular analysis of genetic changes in the origin and development of renal cell carcinoma.

Renal cell carcinoma has been characterized by an abnormality on the short arm of chromosome 3 which suggests the presence of a tumor suppressor gene at this location. In order to more precisely define the location of the renal cell carcinoma gene and to differentiate molecular changes occurring in early stages of renal neoplasia versus those occurring later in malignant progression, DNA from normal and tumor tissue from 60 patients with various stages of renal cell carcinoma was analyzed for loss of alleles at different chromosomal loci. In tumor tissue from 51 of 58 evaluable patients (88%) there was loss of heterozygosity at one or more of 10 loci tested on chromosome 3 independently of tumor stage. Analysis of the genotypes identified the distal portion of 3p bounded by D3S2 and D3S22 (3p21-26) as the region of the disease gene. In tumor tissue from patients with advanced renal cell carcinoma, we found loss of heterozygosity on chromosome 11p in 5 of 21 (24%), on chromosome 13 in 3 of 9 (33%), and on chromosome 17 in 2 of 19 (11%). We found no loss of heterozygosity at the loci on chromosomes 11, 13, or 17 in tumor tissue from patients with localized renal cell carcinoma (N = 5). These data suggest the existence of a tumor suppressor gene on chromosome 3p which may be essential to the genesis of sporadic renal cell carcinoma and that other tumor suppressor genes are associated with progression of this malignancy.

Adult↗
PubMed1991

von Hippel-Lindau disease: inadequacy of angiography for identification of renal cancers.

Selective renal angiograms were retrospectively evaluated for the identification of renal cell cancers in patients with von Hippel-Lindau disease (VHL). Seven patients underwent angiography and surgery because of solid or complex renal masses identified at cross-sectional imaging. Nine kidneys underwent detailed examination by the surgeon and by a pathologist. There were 31 renal cancers. Angiography had enabled identification of only five cancers (16%), and six others (19%) had been suspected. Cancers detected angiographically were larger than those not detected (P less than .05). Solid tumors tended to appear less hypervascular than expected and occasionally had the angiographic appearance of atypical cysts. There were no false-positive angiograms. Angiography revealed only one cancer not previously suspected and changed the surgeon's approach for only one kidney (11%). The sensitivity and specificity of angiography were 35% and 100%, respectively. In these patients, selective renal angiography is not helpful for the detection or exclusion of cancer in a kidney. It does not have a limited role for vascular mapping prior to partial nephrectomy or tumor enucleation.

Adult↗
PubMed1990

Exact random-walk models in crystallographic statistics. V. Non-symmetrically bounded distributions of structure-factor magnitudes.

Derivations of exactly formulated Fourier-series representations of probability density functions (p.d.f.'s) of the magnitude of the structure factor are based on the fact that the structure factor and its real and imaginary parts are bounded. In some situations the bounds of the real and imaginary parts of the structure factor are different, and this gives rise to modified forms of the p.d.f.'s. Three physical examples that call for such modifications are investigated: (i) effect of dispersive scatterers on the p.d.f. of a centrosymmetric structure factor, (ii) effect of the presence of a centrosymmetric fragment in the asymmetric unit of a non-centrosymmetric space group, and (iii) effect of heavy scatterers in special positions of a non-centrosymmetric space group, where the imaginary part of the trigonometric structure factor for these special positions vanishes by symmetry. The general form of an exact Fourier p.d.f., taking account of such modifications, is derived, and expressions for Fourier coefficients are obtained for selected examples of the above three situations. It is seen that the effects of pseudocentrosymmetry may be most pronounced and those of dispersion are significant mainly in the range of small values of the structure factor.

Data Interpretation, Statistical↗
PubMed1990

Clonal growth of bladder cancer cells in a double layer soft agar assay: needles addition of multiple culture supplements.

The necessity of multiple culture supplements, characteristic of Hamburger and Salmon (H&S) soft agar assay (1977), for the clonal growth of bladder cancer cells was systematically investigated. One murine and 6 human cell lines were cultivated in different culture supplemented conditions based on the H&S method. All cell lines successfully formed colonies in the absence of supplements. The inclusion of 2-mercaptoethanol to supplement-free medium stimulated the clonal growth of murine (MBT-2) cells, whereas it did not affect the growth of human cell lines. DEAE-dextran suppressed the clonal growth of 5 out of 7 lines. Tryptic soy broth stimulated the growth of 2 human cell lines, whereas it suppressed the other 2 cell lines. The chemosensitivity of MBT-2 cells was not affected by these supplements.

Animals↗
PubMed1990

Suramin in adrenal cancer: modulation of steroid hormone production, cytotoxicity in vitro, and clinical antitumor effect.

Suramin, a drug known to have antiparasitic effects, has been previously shown to have adrenocorticolytic activity in primates. We now confirm preferential accumulation of this compound in the normal adrenal gland, evaluate its in vitro effect against two human adrenocortical carcinoma cell lines (SW-13 and NCI-H295), and report the clinical activity of suramin in 17 patients with metastatic adrenocortical carcinoma. Inhibition of colony formation occurred in both adrenal cell lines in vitro at concentrations that are clinically achievable in humans. In addition, suramin concentrations as low as 100 micrograms/mL were able to inhibit glucocorticoid, mineralocorticoid, and androgen production by the NCI-H295 cell line. Of 16 patients with adrenocortical carcinoma now evaluable for tumor response, 2 achieved a partial response, 2 had a minor response, and 5 remained with stable disease for periods ranging from 3-10 months; the remainder progressed. One of 7 patients with excessive steroid hormone production achieved a partial normalization of her steroid levels for the duration of suramin therapy in the setting of radiographic disease stabilization. An additional patient treated off-study for lack of radiographically measurable disease, achieved complete normalization of plasma aldosterone levels. We conclude that suramin preferentially accumulates in adrenal cells, induces cytotoxicity and significant down-regulation of steroid hormone production in vitro, and has some therapeutic efficacy as a single agent in patients with metastatic adrenocortical carcinoma.

Adrenal Cortex Neoplasms↗
PubMed1989

Exact conditional distribution of a three-phase invariant in the space group P1. I. Derivation and simplification of the Fourier series.

An exact expression is derived for the conditional probability density function of a three-phase invariant and the general result is applied to the space group P1. The expression for the conditional density is given in terms of a sixfold Fourier series. A straightforward numerical evaluation of this series, without further analysis, is extremely time consuming. Much of the present paper is therefore devoted to an exposition of symmetries hidden in the various summations. The computational effort required for the evaluation of the above expression is thereby reduced to manageable proportions in a number of interesting cases. Results of numerical computations of the exact conditional density are given in the second paper in this series. It is also shown that the exact expression for the conditional probability reduces to that given by Cochran [Acta Cryst. (1955), 8, 473-478].

Chemistry, Physical↗
PubMed1989

Exact conditional distribution of a three-phase invariant in the space group P1. II. Calculations and comparison with the Cochran approximation.

The conditional probability density function of a three-phase invariant is computed from exact expressions derived and discussed in the first paper of this series [Shmueli, Rabinovich & Weiss (1989). Acta Cryst. A45, 361-367] and comparisons are presented of these computations with the approximate conditional density due to Cochran [Acta Cryst. (1955), 8, 473-478]. Conditional variances computed from the exact and approximate expressions are also compared. The computations are carried out for the space group P1. This is the first numerical comparison of conditional phase-invariant statistics evaluated from exact and approximate expressions. The discrepancy between these two kinds of statistics appears to be negligible if the E values involved are small and the number of atoms in the cell is moderately large. Very significant discrepancies are observed when the number of the atoms in the unit cell is small, as well as in the case of the presence of an outstandingly heavy atom. For a given triplet of magnitudes of E values or a fixed atomic composition of the unit cell the exact conditional density functions tend to have sharper peaks than the approximate ones.

Chemistry, Physical↗
PubMed1989

Explicit Fourier representations of non-ideal hypercentric P.D.F.'s of magnitude of E.

Explicit non-ideal hypercentric distributions of the magnitude of the normalized structure factor have been derived and investigated for the space group P1. One of the distribution types investigated arises when the asymmetric unit of P1 consists of several identical centrosymmetric motifs, interrelated by additional non-crystallographic centres of symmetry. The ideal version of such distributions was studied by Rogers & Wilson [Acta Cryst. (1953), 6, 439-449]. The other distribution type studied originates from atomic arrangements in which the asymmetric unit is composed of several unrelated centrosymmetric fragments that may differ in their sizes and chemical compositions. Explicit non-ideal probability density functions (p.d.f.'s) of the magnitude of the normalized structure factor were formulated for both above types of distribution as Fourier series, were evaluated numerically and were compared with appropriately simulated distributions of magnitude of E. The computations were carried out for a range of atomic compositions, and numbers of unrelated centrosymmetric fragments that comprise the asymmetric unit; both of these factors have a significant influence on the deviation of the hypercentric p.d.f.'s from the values predicted on the basis of the central-limit theorem approximation.

Crystallography↗
PubMed1988

Exact random-walk models in crystallographic statistics. IV. P.d.f.'s of [E] allowing for atoms in special positions.

The effect of scatterers, located in variable special positions, on the probability density function of the magnitude of the normalized structure factor has been investigated. Exact characteristic functions have been obtained for all the statistically different variable special positions in triclinic, monoclinic and ortho-rhombic space groups except in Fdd2 and in the space groups based on the point group 222, and the probability density functions have been evaluated from their Fourier or Fourier-Bessel series expansions. It is seen that the effect of heavy scatterers, located in the special positions investigated, is very marked and should be accounted for in cases of space-group ambiguities.

Crystallography↗
PubMed1988

Interleukin 2 suppression of a murine bladder cancer implanted into kidney, bladder and skin; its organ specificity.

Little is known about organ associated tumor response to systemic interleukin 2 (IL2) therapy. The effect of IL2 on bladder cancer growth in the skin and in the genitourinary tract was investigated. C3H mice were implanted with the syngeneic transitional cell carcinoma, MBT-2, intradermally (i.d.), beneath the left renal subcapsular area, and in one experiment, simultaneously in the bladder. IL2 (human recombinant form; Biogen Research Co) was given i.p. at 5000 U thrice daily for 5 consecutive days commencing on Day 3, or for 10 to 11 days commencing on Day 10 with some doses omitted at signs of toxicity. For comparison, mice bearing 3-d and 10-d tumors in the skin and subcapsular kidney were treated with chemotherapy (cisplatin, 6 mg./kg. X 3; mitomycin C, 3 mg./kg. X 3; cyclophosphamide, 75 mg./kg. X 1). IL2 therapy mediated growth suppression of 10-d tumors in the genitourinary organs and skin at a similar rate. In contrast to IL2, systemic chemotherapy mediated tumor suppression in an organ specific manner; renal subcapsular tumors responded to the chemotherapy, whereas i.d. tumors were insensitive. Three-day tumors (both i.d. and renal subcapsular tumor) responded relatively well to each treatment compared to 10-d tumors. These data suggest that in systemic immunotherapy with IL2, anatomic location of the tumor is less important for inducing an antitumor response than in chemotherapy.

Animals↗
PubMed1986

Predicting posttraumatic epilepsy in penetrating head injury.

Using data derived from a 15-year follow-up study of 520 veterans surviving penetrating brain wounds received in the Vietnam war, we have developed a predictive formula and tables for posttraumatic epilepsy based on time elapsed postinjury and presence of specific clinical and computed tomographic scan risk factors. Such patients remain at some increased risk for epilepsy even ten to 15 years postinjury, although most can be 95% certain of avoiding epilepsy if they have been seizure free for three years posttrauma. Epilepsy onset latency was independent of any risk factors identified.

Brain Injuries↗
PubMed1979

Cranioplasty: a review of 1030 cases of penetrating head injury.

A total of 491 cranioplasties performed in a population of 1030 cases of penetrating head injury are reviewed. The morbidity rate was 5.5%, and the mortality rate was 0.2%. The clinical criteria of improving cosmetic defects and restoring craniocerebral protection are established, based on the location and size of the skull defect. Cranioplasty after penetrating head injury should be deferred for a minimum of 1 year to control morbidity. Complication of the original injury and surgical debridement increase the morbidity rate of cranioplasty. Post-traumatic epilepsy is not related to skull defects per se; neither is it affected by cranioplasty. Acrylic is an acceptable cranioplasty material if there is strict adherence to good surgical technique.

Acrylic Resins↗