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Biomedical subjects

R Weiss

Publications and source records attributed to R Weiss.

At least 271 records · Page 15Linked to original sources
PubMed1991

[Bone marrow changes in patients with thyroid carcinoma].

In 62 patients with thyroid carcinoma 79 MRI bone marrow examinations and 48 bone marrow scintigraphies were recorded before or following radioiodine therapy, to study the extent of bone marrow expansion. The results of both methods were the same. In 34/79 investigations normal findings were seen, in 18 the bone marrow expanded to the middle third and in 26 to the distal third of the femur. One patient showed bone marrow expansion to the tibia. These results were compared with the following data: histology of tumor, TNM-staging, time passed since thyroidectomy, accumulated doses of radioiodine therapy, results of 131I scintigraphy, hematological changes, thyroglobulin level, age and sex. No significant correlations were found between these and the bone marrow imaging results. Bone marrow changes in patients before radioiodine therapy were similar to those in patients treated with up to 48 GBq 131I. Blind biopsy of the posterior iliac crest in five patients showed slightly pathological reactive changes. In only 2/17 follow-up studies an increase of bone marrow expansion was seen. In 8 patients localized findings indicating malignant infiltration were observed. In 4/8 patients metastases of thyroid carcinoma were known or confirmed by pathological radioiodine uptake and in 2/8 metastatic involvement was assumed because of an increased thyroglobulin level.

Adenocarcinoma↗
PubMed1991

Relative accuracy of three scintigraphic methods for determination of right ventricular ejection fraction: a correlative study with ultrafast computed tomography.

The accuracy of three scintigraphic methods for determination of right ventricular ejection fraction (RVEF) was tested in 29 patients using ultrafast computed tomography (UFCT) as the gold standard. RVEF measurements by the ECG-gated first-pass approach showed excellent correlation with the UFCT results (r = 0.96, y = 0.06 + 0.91x), while both the standard gated acquisition blood-pool imaging (r = 0.71, y = 0.14 + 0.59x) and the nongated first-pass curve approach (r = 0.63, y = 0.18 + 0.37x) significantly underestimated RVEF. The error can be ascribed to partial inclusion of the atrial activity in the region assigned to the right ventricle. The tricuspid valve plane was found to move by a distance equal to 9%-33% (mean = 20%) of the right ventricular long-axis between systole and diastole. This translational motion was more pronounced with higher EFs.

Adult↗
PubMed1991

Hand-mirror variant of microgranular acute promyelocytic leukemia.

We report a case of microgranular acute promyelocytic leukemia (APL, M3 V) presenting with the typical features of disseminated intravascular coagulopathy and cells with irregular, folded, or bilobed nuclei with occasional intracytoplasmic multiple Auer rods in the peripheral blood. A cytogenetic study of the bone marrow and blood showed translocation between chromosomes 15 and 17, characteristic of APL. The flow cytometric study also confirmed this diagnosis. The unusual feature in this case is the existence of 80% hand-mirror cells, which also contain multiple Auer rods, in the bone marrow. The hand-mirror variant of acute leukemia has been frequently encountered in acute lymphoblastic leukemia, but documented in only six cases of acute myelogenous leukemia, including the FAB groups of M1, M2, M4, and M5. This patient is, to our knowledge, the first reported case of a hand-mirror variant in microgranular APL. The mechanism of hand-mirror cell formation and its prognostic implication are discussed.

Bone Marrow↗
PubMed1991

[Studies in riding arenas and on different riding path surfaces with respect to respiratory tract contamination in horses. Air hygiene studies in riding arenas].

Using the direct sedimentation method, the air pollution with fungal spores was measured in indoor riding arenas and compared to horse stables, outside riding arenas and covered sport courts. Depending on the location of indoor arenas and stables, the presence of "dust-nests", the number of horses ridden, and the moisture of the tread layer, an air pollution was measured which was equivalent to that in stables except at times of feeding and straw-giving. Outside and in sport arenas a low air pollution was found. Recommendations are given, regarding optimum air hygiene especially for horses with chronic and subclinical respiratory conditions.

Air Microbiology↗
PubMed1990

The catalytic domain of the neurofibromatosis type 1 gene product stimulates ras GTPase and complements ira mutants of S. cerevisiae.

Sequencing of the neurofibromatosis gene (NF1) revealed a striking similarity among NF1, yeast IRA proteins, and mammalian GAP (GTPase-activating protein). Using both genetic and biochemical assays, we demonstrate that this homology domain of the NF1 protein interacts with ras proteins. First, expression of this NF1 domain suppressed the heat shock-sensitive phenotype of yeast ira1 and ira2 mutants. Second, this NF1 domain, after purification as a glutathione S-transferase (GST) fusion protein, strongly stimulated the GTPase activity of yeast RAS2 and human H-ras proteins. The GST-NF1 protein, however, did not stimulate the GTPase activity of oncogenic mutant ras proteins, H-rasVal-12 and yeast RAS2Val-19 mutants, or a yeast RAS2 effector mutant. These results establish that this NF1 domain has ras GAP activity similar to that found with IRA2 protein and mammalian GAP, and therefore may also regulate ras function in vivo.

Cloning, Molecular↗
PubMed1990

Highly complex genetic rearrangement involving at least seven breakpoints in a case of chronic myeloid leukemia.

Cytogenetic analysis for an atypical case of chronic myeloid leukemia (CML) showed a complex karyotype with four chromosome breakpoints (5q12, 12q21, 12q24, and 22q11) and translocation products that included a typical Philadelphia chromosome but apparently normal chromosomes 9. Molecular genetic analyses using four breakpoint cluster region (bcr) probes indicated that three breaks were probably present on chromosome 22. Two apparently independent breaks appeared to exist within the bcr, one of which was probably associated with a deletion of some bcr sequences. By combining the molecular and cytogenetic data, we could infer a total of seven breaks. This case illustrates the extensive and complex types of genetic alteration that may be associated with a c-abl and bcr fusion.

Chromosome Aberrations↗
PubMed1990

A major segment of the neurofibromatosis type 1 gene: cDNA sequence, genomic structure, and point mutations.

Overlapping cDNA clones from the translocation breakpoint region (TBR) gene, recently discovered at the neurofibromatosis type 1 locus and found to be interrupted by deletions and a t(17;22) translocation, have been sequenced. A 4 kb sequence of the transcript of the TBR gene has been compared with sequences of genomic DNA, identifying a number of small exons. Identification of splice junctions and a large open reading frame indicates that the gene is oriented with its 5' end toward the centromere, in opposition to the three known active genes in the region. PCR amplification of a subset of the exons, followed by electrophoresis of denatured product on native gels, identified six variant conformers specific to NF1 patients, indicating base pair changes in the gene. Sequencing revealed that one mutant allele contains a T----C transition changing a leucine to a proline; another NF1 allele harbors a C----T transition changing an arginine to a stop codon. These results establish the TBR gene as the NF1 gene and provide a description of a major segment of the gene.

Amino Acid Sequence↗
PubMed1990

Evidence for variable metal-radical spin coupling in oxoferrylporphyrin cation radical complexes.

Oxoferrylporphyrin cation radical complexes were generated by m-chloroperoxybenzoic acid oxidation of the chloro and trifluoromethanesulfonato complexes of tetramesitylporphyrinatoiron(III) [(TMP)Fe] and the trifluoromethanesulfonato complex of tetra(2,6-dichlorophenyl)porphyrinatoiron(III) [TPP(2,6-Cl)Fe]. Coupling between ferryl iron (S = 1) and porphyrin radical (S' = 1/2) spin systems was investigated by Mössbauer and EPR spectroscopy. The oxoferrylporphyrin cation radical systems generated from the TMP complexes show strong ferromagnetic coupling. Analysis of the magnetic Mössbauer spectra, using a spin Hamiltonian explicitly including a coupling tensor J, suggests an exchange-coupling constant J greater than 80 cm-1. The EPR spectra show non-zero rhombicity, the origin of which is discussed in terms of contributions from the usual zero-field effects of iron and from iron-radical spin-dipolar interaction. A consistent estimate of zero-field splitting parameter D approximately + 6 cm-1 was obtained by EPR and Mössbauer measurements. EPR and Mössbauer parameters are shown to be slightly dependent on solvent, but not on the axial ligand in the starting (TMP)Fe complex. In contrast to the TMP complex, the oxoferrylporphyrin cation radical system generated from [TPP(2,6-Cl)FeOSO2CF3] exhibits Mössbauer and EPR spectra consistent with weak iron-porphyrin radical coupling of magnitude of J approximately 1 cm-1.

Chemical Phenomena↗
PubMed1990

The effect of an alpha-2 agonist on bladder function and cord histology after spinal cord injury.

Spinal injury in cats is accompanied by urinary bladder and hind limb dysfunction. Ten cats subjected to spinal contusion at the ninth thoracic segment were treated with guanabenz (an alpha-2 agonist) intraperitoneally (0.65 mg./kg.) three hours after injury, and twice daily for eight weeks. An additional six spinal cats were untreated and served as controls. Urodynamic studies were performed on a weekly basis on all animals. Guanabenz modified the vesico-somatic reflex: detrusor-sphincter dyssynergia was either ablated or abolished. In contrast, the controls demonstrated detrusor-sphincter dyssynergia, high residual urine, and spasticity below the lesion. Histological evaluations of the spinal cords revealed that the six paraplegic animals (untreated) suffered marked cavitation of the cord and complete destruction of the grey matter. The five incomplete paraplegic animals (treated) showed minimal cavitation with some preservation of the grey matter. The five ambulators (treated) demonstrated some distortion of grey matter with preservation of white matter. Treatment with guanabenz post traumatic cord injury results in decreased cord cavitation. Detrusor-sphincter dyssynergia is diminished and hind limb function is improved in treated animals.

Adrenergic alpha-Agonists↗
PubMed1990

Studies of antigenic components in acid extracts of group C streptococci with special reference to Streptococcus equi.

For the determination of a species-specific antigen of Streptococcus (S.) equi, acid extracts of group C streptococcal strains from horses (S. equi, S. zooepidemicus, S. equisimilis) were investigated using polyacrylamide gel electrophoresis and the immunoblotting technique. Using sera of horses suffering from strangles as well as sera from horses with respiratory infection of unknown etiology, Western blotting yielded more or less multiple banding reactions with bands in the 70, 54, 42, 40, and 31-28 kd molecular weight ranges against extracts of all of the 3 different bacterial species. However, an antigen found in this study at 18-16 kd which was highly sensitive to trypsin, proved to react specifically and regularly only with the serum of horses exposed to S. equi. The specificity of the reaction was assured by antisera of rabbits and horses vaccinated against S. equi, S. zooepidemicus or S. equisimilis, respectively, and by cross absorption of a serum originating from a mare recovered from strangles with Lancefield group C and group G streptococci as well as a strain of S. pyogenes. According to Western blot results on 180 serum pairs from horses with clinical signs of respiratory infection, 15.6% of which gave positive reactions, the 18-16 kd antigen appears as a marker suitable for qualitative testing of horse sera for antibodies to S. equi.

Absorption↗
PubMed1990

HIV infection and health policy.

The epidemic of human immunodeficiency virus (HIV) infection has given an urgency to health policy dilemmas that have long been brewing. By exacerbating long-standing problems, the epidemic has surpassed what we find tolerable and has pressured politicians and health officials to find solutions. Whether the approaches they take will substantially contribute to solving the underlying problems is unclear. Many persons engaged in health policy believe that in responding to the AIDS crisis we may be defining our society for future historians. Judgement may be passed on how compassionately we care for those who are sick, how effectively we choose our public health measures, and how creatively we apply our scientific knowledge. This paper addresses six challenges that face policymakers: (a) protecting people from discrimination, (b) designing testing and screening programs, (c) developing safe and effective antiviral drugs, (d) planning for future vaccine trials, (e) organizing and delivering health care to sufferers of HIV infection, and (f) financing such health care.

Delivery of Health Care↗
PubMed1990

Hitting the target.

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Community-Institutional Relations↗