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Biomedical subjects

W Kammerer

Publications and source records attributed to W Kammerer.

7 recordsLinked to original sources
PubMed1992

The management of subglottic stenosis in patients with Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a multisystem inflammatory disease characterized by vasculitis, granuloma formation, and necrosis. Among 158 patients treated at the National Institutes of Health during the past 24 years, 145 (92%) had an otolaryngologic manifestation of their disease and 25 (16%) had subglottic stenosis (SGS). SGS varied from asymptomatic to life-threatening. Sixteen (80%) of 20 patients with fixed SGS required surgical intervention, including manual dilations, carbon-dioxide laser resections, and laryngotracheoplasty (LTP). LTP was performed with and without microvascular reconstruction. Thirteen of the patients required tracheostomy and all 13 were ultimately decannulated. Five patients who repeatedly failed dilations and/or endoscopic laser surgery underwent LTP. Since 1987, two patients have undergone LTP with microvascular free flaps. Both patients were subsequently decannulated. The authors' experience demonstrates that management of SGS in WG is complex, requiring individualized frequent multimodality interventions to achieve satisfactory results. Microvascular laryngotracheal reconstruction should be considered in the surgical armamentarium for patients with persistent stenoses.

Adolescent↗
PubMed1991

Developmental genetic studies of the moss, Physcomitrella patens.

The development of the haploid gametophyte stage of Physcomitrella patens presents excellent opportunities for the detailed study of plant morphogenesis at the cellular level. The filamentous protonema undergoes a number of developmental transitions that can be observed directly in living material using time-lapse video microscopy and that can be manipulated both by treatment with phytohormones and by environmental stimuli. Mutants affecting these processes can be isolated and can be analysed using conventional as well as parasexual methods. Molecular biological techniques are now being established since these will be essential if the mechanisms that bring about morphogenetic processes are to be understood at the molecular level. A technique for genetic transformation has been devised and is being exploited to attempt to tag developmentally-relevant genes using maize transposons. Changes in gene activity associated with developmental transitions and in response to treatment with phytohormones and environmental stimuli are being studied using cDNA library subtraction techniques. Heterologous genes involved in the control of transcription and of the cell cycle are being used to probe the P. patens genome to identify possible homologues involved in developmental regulation.

Cytokinins↗
PubMed1988

Enflurane metabolism produces covalently bound liver adducts recognized by antibodies from patients with halothane hepatitis.

The existence of a rare syndrome of "enflurane hepatitis" similar to that described for halothane and of a cross-sensitization between halothane and enflurane has been controversial, largely due to equivocal clinical case reports and a lack of a plausible molecular mechanism for the hepatotoxicity. The present study suggests a possible hypersensitivity basis for enflurane hepatitis and the apparent cross-sensitization between halothane and enflurane involving covalently bound liver microsomal adducts. Immunoblotting studies have revealed that antibodies in the sera of six patients with halothane hepatitis recognize liver microsomal antigens of Mr = 100,000, or both 100,000 and 76,000, formed in rats treated with enflurane or halothane. These antigens were not detected in microsomes from isoflurane- or sesame oil-treated rats. The recognition of these antigens could be abolished by preincubation of the sera with microsomes from halothane-treated rats. These data suggest that the difluoromethoxydifluoroacetyl halide metabolite of enflurane, as well as the trifluoroacetyl halide metabolite of halothane, covalently bind to similar hepatic proteins, and may become immunogens in susceptible patients. This mechanism may also account for the apparent cross-sensitization between halothane and enflurane anesthesia, and the development of hepatic necrosis.

Animals↗
PubMed1987

Large-scale preparation of a DNA fragment containing the strong promoter A1 of the phage T7.

A procedure has been developed to isolate DNA fragments on a large scale. A DNA fragment of 130 base-pairs containing the strong promoter A1 of the phage T7 was purified to homogeneity in amounts of 10 mg. The procedure includes the rapid purification of gram amounts of plasmid DNA, a new, simple method to separate small DNA fragments from the vector by a phenol/water partitioning system, and a liquid-liquid PEG-dextran partition chromatography for the final purification of the fragment. The fragment was cloned in two vector systems: The vector pDS1, to1+ (1), containing an efficient terminator downstream from the promoter integration site, gives high yields, 3-4 mg plasmid DNA per liter medium. In the plasmid pWH802 (2), which is not specially designed for the amplification of a strong promoter, the integration of the promoter was possible but the yield decreased by a factor of about 50. The stability of the inserts was tested in both systems. Monomeric inserts were stable in both plasmids, multimeric inserts up to a tetramer were only stable in pWH802. Only one orientation of the fragment was found.

Biotechnology↗
PubMed1986

Promoters of Escherichia coli: a hierarchy of in vivo strength indicates alternate structures.

The strength in vivo of 14 promoters was determined in a system which permits the quantitation of RNA synthesis with high accuracy. Up to 75-fold differences in promoter strength were measured and the most efficient signals are promoters from coliphages T7 and T5. Their activity approaches the strength of fully induced promoters of the rRNA operons which may be close to the functional optimum of a single sequence. By contrast, a synthetic 'consensus promoter' belongs to the less efficient signals. Our data show that optimal promoter function can be achieved by alternate structures and strongly suggest that information outside of the 'classical' promoter region contributes to promoter activity.

Base Sequence↗
PubMed1986

Functional dissection of Escherichia coli promoters: information in the transcribed region is involved in late steps of the overall process.

After binding to a promoter Escherichia coli RNA polymerase is in contact with a region of about 70 bp. Around 20 bp of this sequence are transcribed. Information encoded within this transcribed region is involved in late steps of the functional program of a promoter. By changing such 'down-stream' sequences promoter strength in vivo can be varied more than 10-fold. By contrast, information for early steps of the promoter program such as recognition by the enzyme and formation of a stable complex resides in a central core region of about 35 bp. Our data show that the strength of a promoter can be limited at different levels of the overall process. Consequently promoters of identical strength can exhibit different structures due to an alternate optimization of their program.

Base Sequence↗