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Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 613 records · Page 34Linked to original sources

Conformation and dynamics of the Pribnow box region of the self-complementary d(C-G-A-T-T-A-T-A-A-T-C-G) duplex in solution.

Nuclear magnetic resonance (NMR) has been used to monitor the conformation and dynamics of the d(C1-G2-A3-T4-T5-A6-T6-A5-A4-T3-C2-G1) self-complementary dodecanucleotide duplex (henceforth called Pribnow 12-mer), which contains a TATAAT Pribnow box and a central core of eight dA X dT base pairs. The exchangeable imino and nonexchangeable base protons have been assigned from one-dimensional intra and inter base pair nuclear Overhauser effect (NOE) measurements. Premelting conformational changes are observed at all the dA X dT base pairs in the central octanucleotide core in the Pribnow 12-mer duplex with the duplex to strand transition occurring at 55 degrees C in 0.1 M phosphate solution. The magnitude of the NOE measurements between minor groove H-2 protons of adjacent adenosines demonstrates that the base pairs are propeller twisted with the same handedness as observed in the crystalline state. The thymidine imino proton hydrogen exchange at the dA X dT base pairs has been measured from saturation recovery measurements as a function of temperature. The exchange rates and activation barriers show small variations among the four different dA X dT base pairs in the Pribnow 12-mer duplex.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

Phalloidin shift on velocity sedimentation sucrose gradient centrifugation for identification of microfilament-associated proteins.

Velocity sedimentation by sucrose density gradient centrifugation has been used to characterize ascites microvillar microfilament cores and to identify microfilament-associated proteins. Fluoride, calcium, phalloidin and chemical cross-linking treatments of microvilli during Triton X-100 extractions increase the sedimentation rate of the microfilament core, compared with untreated control samples. Electrophoretic analyses of the distributions of actin, alpha-actinin and other microfilament-associated proteins across the gradients indicate that the primary mechanism for stabilization of the microfilament core is the reduction of fragmentation of the microfilaments. Significantly, alpha-actinin could be completely removed from the microfilaments by calcium treatment without causing a decrease in the size of the microfilament core. Because of the specificity of phalloidin in the stabilization of microfilaments, the shift on the gradients of microfilaments and their associated proteins in the presence of phalloidin provides a diagnostic tool for the identification of microfilament-associated proteins. This phalloidin shift technique should have widespread utility in the analysis of actin forms and microfilament-associated proteins from complex cell fractions.

Actin Cytoskeleton↗

Fibrinolytic therapy of St. Jude valve thrombosis under guidance of digital cinefluoroscopy.

Fibrinolytic therapy is an alternative to urgent reoperation for patients with St. Jude prosthetic valve thrombosis, but requires an accurate method for repeated assessment of prosthetic function. Since the St. Jude valve is not well visualized by conventional cinefluoroscopy, digital subtraction techniques were developed that improved visualization of the value and allowed assessment of leaflet separation and velocity. A 74 year old woman with prosthetic valve thrombosis 5 years after St. Jude aortic valve placement had an opening angle of 58 degrees (normal range 10 to 13; n = 8) with a maximal opening velocity of 1.37 degrees/ms (normal range 2.46 to 2.93). The closing angle was 125 degrees (normal range 120 to 127) with a maximal closing velocity of 1.38 degrees/ms (normal range 2.24 to 3.60). The patient received 250,000 U of streptokinase intravenously, then 100,000 U/h for 72 hours. Improvement in auscultatory findings occurred at 12 hours; repeat digital cinefluoroscopy showed an opening angle of 20 degrees with a maximal velocity of 2.77 degrees/ms, and a closing angle of 126 degrees with a maximal velocity of 1.91 degrees/ms. Digital cinefluoroscopy 4 weeks after discharge on warfarin and dipyridamole therapy was unchanged. There have been no thromboembolic complications after 6 months of follow-up. Thus, digital cinefluoroscopy is a new noninvasive technique that permits accurate measurement of normal and abnormal St. Jude leaflet function. Intravenous streptokinase dissolution of prosthetic valve thrombosis under digital cinefluoroscopic guidance may be an acceptable alternative to emergency reoperation. The frequency and significance of residual subclinical leaflet dysfunction after fibrinolytic therapy and the indications for elective reoperation require further evaluation.

Aged↗

The nucleocapsid of Berne virus.

In Berne virus-infected cells and in gradient-purified virions two major proteins with mol. wt. of 20K and 22K were detected. The 22K species is thought to represent the main envelope polypeptide; in infectious culture media it was present in a low envelope polypeptide; in infectious culture media it was present in a low density substructure which could be quantitatively converted into slowly sedimenting material by detergent treatment. The 20K polypeptide (accounting for about 80% of the 14C-amino acid label in the virion) was phosphorylated, occurred in an intracellular substructure of higher density than the virion (rho = 1.36 g/ml in CsCl) and was the only viral protein possessing RNA-binding properties; it was recognized preferentially by heterologous animal sera in immune precipitation. The 20K species is therefore identified as the main capsid protein. Two additional polypeptides (19K and 17K) were regularly detected in extracts of infected cells; they appeared to share oligopeptides with the 20K protein and are interpreted as being proteolytic cleavage products. The nucleocapsid of Berne virus was visualized after ether treatment as a flexible bacilliform structure with conspicuous transverse striation. Demonstration of a 20K nucleocapsid protein further supports the authors' proposal that Berne virus is a representative of a new family of enveloped RNA viruses (Toroviridae).

Animals↗

Liver-specific RNA metabolism in hepatoma cells: variations in transcription rates and mRNA levels.

The transcription rate and abundance of several liver-specific mRNAs as well as mRNAs common to many cell types were compared in a series of rodent hepatoma cell lines, normal liver cells, and primary hepatocyte cultures. The rat hepatoma cell line, Fao, which displays a liver-specific phenotype, contained eight of eight liver-specific mRNAs examined. However, the transcription rates of most liver-specific mRNAs were found to be low (1 to 30%) compared with normal liver in this and other differentiated cell lines. This low rate is similar to the transcription rates of liver-specific mRNA sequences measured in primary cultures of hepatocytes. Several variant cell lines that had lost differentiated traits contained few or none of the liver-specific mRNAs; clonal descendents which had regained differentiated function regained the tissue-specific mRNAs as a group, but at various concentrations. Because all of the changes observed in mRNA levels were not accompanied by parallel changes in transcription of the same sequences, differential posttranscriptional stabilization of the liver-specific mRNAs must also occur in the different cell lines. These results qualify the utility of cultured cell lines in the study of tissue-specific transcriptional control, but raise the possibility that posttranscriptional mechanisms act in cooperation with transcriptional controls to bring the level of tissue-specific mRNAs closer to those found in liver cells.

Albumins↗

Effects of dietary linoleic acid enrichment on induction of immune complex nephritis in mice.

In pharmacologic doses E series prostaglandins attenuate the development of immune complex nephritis. We studied the effect of the dietary prostaglandin precursor linoleic acid on murine apoferritin-induced immune complex glomerulonephritis. High, normal, or low linoleic acid diets were fed to mice for 4 weeks prior to and during the intraperitoneal apoferritin administration. A high linoleic acid diet feeding was associated with less proteinuria, less renal histologic damage, and prevented a rise in serum creatinine. We conclude that linoleic acid has a protective effect on the development of murine apoferritin-induced immune complex nephritis.

Animals↗

The radiographic evaluation of spinal trauma.

The authors describe a systematic approach to the radiographic evaluation of spinal trauma, discussing cervical spine anatomy, the mechanism of injury, and classification of injuries, and then discuss several specific injuries of the cervical and thoracolumbar spine and their radiographic evaluation.

Cervical Vertebrae↗

[Treatment of coronary disease with elantan. Results of a multicenter study].

10,229 patients with coronary heart disease (CHD) took part in a multicenter study to verify the efficacy and tolerance of a 14 days lasting therapy with elantan under practical conditions. The majority of patients with an average age of 59 +/- 10 years (58.8% men, 40.3% women) had suffered about four years on CHD and had already been treated with coronary efficient drugs. The 14-day therapy with elantan 20 in a dosage of 3 X 1 tabl./day showed a cure rate of 79.9% in patients who had already been treated, a complete remission of the angina pectoris attacks being achieved in 50% and a reduction of the frequency of the attacks in a further 29.9%. The reduced frequency of the attacks was associated with a reduced consumption of acute nitrates (nitroglycerine capsules). With the smaller group of patients who were being treated for angina pectoris for the first time, the therapy with elantan was characterized by a cure rate of 91%.

Angina Pectoris↗