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Biomedical subjects

B Haas

Publications and source records attributed to B Haas.

At least 109 records · Page 6Linked to original sources
PubMed1988

The 7S RNA from tomato leaf tissue resembles a signal recognition particle RNA and exhibits a remarkable sequence complementarity to viroids.

From tomato leaf tissue we sequenced and characterized a 7S RNA which consists of 299 nucleotides with either two or three additional uridine nucleotides at its 3'-terminus. About 56% of the nucleotides of this higher plant 7S RNA are in nearly identical positions as those of the human 7SL RNA which is an integral component of the signal recognition particle (SRP) that mediates protein translocation. Computer modelling and digestion studies with nucleases led to a secondary structure model for tomato 7S RNA, the overall shape of which is very similar to that of the human 7SL (SRP) RNA. This structural similarity strongly suggests that tomato 7S RNA is actually an SRP RNA and an integral part of the plant SRP, and that the protein translocation system of higher plants is very similar to the one operating in mammalian cells. Tomato SRP RNA contains a stretch of 36-53 nucleotides which exhibit a high degree of sequence complementarity to five viroid 'species' that cause disease in tomato. In the case of potato spindle tuber viroid and citrus exocortis viroid this complementarity spans the lower strand of the region, the nucleotides of which are known to modulate virulence. This extensive sequence complementarity could lead to a thermodynamically favoured base-pairing in vivo which renders the tomato SRP RNA a possible host target with which viroids could interact and thus incite disease.

Base Sequence↗
PubMed1988

Morphohistometric investigations in placentas of gestational diabetes.

Perinatal morbidity and mortality are increased in both overt and gestational diabetes. Since retardation of placental development has been documented in overt diabetes, we, thus, examined morphometrically the terminal villi of 26 patients with gestational diabetes in order to determine if there is an immaturity of placental development. Investigation of villous surface, degree of vascularization, and development of epithelial plates yielded values lying somewhere between those of non-diabetic patients and those of patients with overt diabetes. Only the surface areas of the vessels were reduced to levels lower than in overt diabetes. Our findings appear to explain the occasional development of acute placental insufficiency.

Blood Vessels↗
PubMed1988

Salvage of infected total knee arthroplasty.

Between 1981 and 1986, 25 patients with 26 infected total knee arthroplasties (TKAs) were treated with complete debridement of the knee, prosthetic removal, and six weeks of intravenous antibiotics, followed by insertion of a new prosthesis. The patients were followed for 12-57 months (average, 29 months). There was no evidence of residual infection at follow-up examination in any case. Applying the Hospital for Special Surgery knee rating system, 12 patients (50%) were rated excellent, six patients (25%) good, two patients (9%) fair, and four patients (6%) poor. Of the six patients with fair and poor results, five had reduced scores due to joint problems unrelated to the infected TKA. Fourteen patients had no pain at follow-up examination, and four had only slight pain. Nine patients had no limp, ten had a slight limp, one had a moderate limp, and the remainder either had a severe limp or were bedridden due to other joint problems. Eight patients could walk an unlimited distance and four could walk at least one-half mile. Twenty-one knees had a range of flexion greater than 90 degrees. Three patients had extensor lags of 20 degrees or greater. Only one patient required bracing for ambulation.

Aged↗
PubMed1986

Fetal adenoma of the pigmented ciliary epithelium associated with persistent hyperplastic primary vitreous.

A 1.5-year-old girl presented with a peripheral iris mass. When the girl was 3 years old, the lesion was excised after it had manifested significant growth. A stalk of fibrovascular tissue was noted to extend from the lesion to the optic disc. Histopathologically, the tumor was a well-circumscribed, pigmented ciliary body adenoma. Electron microscopy revealed characteristic neuroepithelial melanosomes, distinct from those of choroidal melanocytes, and occasional annulate lamellae. A fibrovascular membrane extended over the tumor surface and was adherent to lens capsule. The association of this adenoma with a persistent stalk of primary vitreous indicates a congenital origin of this tumor. Both adenoma and adenocarcinoma of the pigmented and nonpigmented ciliary epithelium tend to be disorders of adults. The authors report the youngest presentation of a pigment epithelium adenoma, the only well-documented case associated with persistent hyperplastic primary vitreous, and the only documentation of annulate lamellae in a ciliary body tumor.

Adenoma↗
PubMed1986

Purification and properties of an intranuclear virus-specific antigen from tissue infected with Borna disease virus.

A virus-specific antigen was extracted from brains of rats and from MDCK cells infected with Borna disease (BD) virus and purified to homogeneity by immunoaffinity chromatography and HPLC. The antigen consists of two components which are almost equal in size (38 000 mol. wt.), and it forms aggregates in its native form. The virus specificity of the two antigenic entities was confirmed by immunoblots with convalescent serum and monoclonal antibodies. Immunofluorescent staining with monoclonal antibodies and a hyperimmune serum prepared against the purified antigen showed the intranuclear fluorescence typical for BD virus-infected cells.

Animals↗
PubMed1985

Correlation between structure and pathogenicity of potato spindle tuber viroid (PSTV).

Sequence analysis by primer-extension at the level of their cDNA showed that the RNA genomes of various field isolates of potato spindle tuber viroid (PSTV) of different virulence differ from each other only in a few nucleotides in two distinct regions of the rod-shaped molecule. Despite insertions and deletions the chain length of 359 nucleotides is strictly conserved in all the isolates studied. Thermodynamic calculations revealed that due to the observed sequence differences the region located at the left hand part of the rod-like secondary structure of the PSTV molecule, denoted 'virulence modulating (VM) region', becomes increasingly unstable with the increasing virulence of the corresponding isolate. Based on these data we propose in molecular terms a model for the mechanism of viroid pathogenicity. It implies that the nucleotides of the VM region specify and modulate the binding- and hence the competition-potential of the PSTV RNA molecule for a still unknown host factor(s) and thus determine the virulence of PSTV.

Base Sequence↗
PubMed1983

Oligomeric forms of potato spindle tuber viroid (PSTV) and of its complementary RNA are present in nuclei isolated from viroid-infected potato cells.

Different oligomeric forms of PSTV are detected in nuclei isolated from PSTV-infected potato cells by means of molecular hybridization, using as probes synthetic oligodeoxyribonucleotides with sequence specificity for (+)PSTV and for (-)PSTV. In addition to several species of longer-than-unit-length (-)PSTV molecules, two oligomeric forms of (+)PSTV are detected, which correspond in size to RNA strands of approximately two and three times viroid unit-length. They must be considered as the precursors of the circular and linear (+)PSTV monomers accumulating in the cell nucleus.

Base Sequence↗
PubMed1982

Photoluminescent thermometry based on europium-activated calcium sulphide.

A photoluminescent thermometer, based on the transient emission response of a europium-activated calcium sulphide phosphor, is described in detail. This optical thermometry system has special advantages for temperature measurements in microwave and RF fields and potential application in electromagnetically induced clinical hyperthermia. A laboratory system has been constructed which utilises a fibreoptic probe with external diameter 0.8 mm. A system temperature resolution of 0.1 degree C has been achieved in the range 37-47 degrees C.

Calcium↗