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Biomedical subjects

J Wimmer

Publications and source records attributed to J Wimmer.

18 recordsLinked to original sources
PubMed2005

Modeling indicator dispersion in extracorporeal blood lines.

The measurement of indicators such as saline diluted by blood flow provides important information on transport characteristics during extracorporeal blood treatments. When saline is injected and measured using the extracorporeal system, the effects caused by dispersion within the extracorporeal system have to be taken into consideration in order to adequately identify intracorporeal transport characteristics. It was the aim of this study to quantify the extracorporeal contribution and to obtain a transport function for specified sections of the extracorporeal system. The dispersion of saline following an impulsive input was measured in arterial and venous segments of customary extracorporeal blood lines with different distribution volumes (V = 23-87 mL) using a range of different blood flows (Qb = 200-450 ml/min). The dispersion was analyzed using a modified Gamma distribution function characterized by three parameters n, k, and tau, where n is real, positive, and n > or = 1, where k = Qb/Vt*n2, and where tau refers to the indicator appearance time at the sampling site. The parameters n, k, and tau were identified by fitting the model function to experimental data. The value of n was 2.3+/-0.5 and largely independent of the type of line segment, Qb, or Vt tau showed a strong dependence on Vt and Qb which was described by tau = Vt/Qb*(n-1)/n. Thus, with a given n, and when Vt and Qb are known, the transport function for saline in important sections of the extracorporeal circulation can be determined for specific experimental conditions. With this information indicator dilution curves measured in extracorporeal blood lines can be corrected for extracorporeal effects.

Animals↗
PubMed2005

Analysis and evaluation of methodologies to assess technical urban water systems.

The paper reports on the methodology and findings of a recent project on behalf of the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management. The Ministry is seeking procedures for combining ecological and economic criteria to assess which technical urban water alternatives shall receive funding. To this end the current decision making process (DMP) for implementing urban water alternatives in Austria has been analyzed and compared with the situation elsewhere, e.g. in Sweden. The DMP entails specific requirements on assessment, whence the most common decision aid methodologies, ranging from LCA-based to multi-criteria methods, have been described and evaluated from an environmental, economic, legal and practical point of view, turning out recommendations to the Ministry. Their main points are: First the DMP should be kept as simple as possible in order to make it transparent. Second the aggregation of different criteria groups should and can be avoided. Therefore the stakeholders should not be allowed to make trade-offs. Finally clear objectives need to be stated.

Austria↗
PubMed2000

Interactions between equine cyclin T1, Tat, and TAR are disrupted by a leucine-to-valine substitution found in human cyclin T1.

Transcriptional transactivators (Tat) from human immunodeficiency and equine infectious anemia viruses (HIV and EIAV) interact with their transactivation response elements (TAR) to increase the rates of viral transcription. Whereas the human cyclin T1 is required for the binding of Tat to TAR from HIV, it is unknown how Tat from EIAV interacts with its TAR. Furthermore, Tat from EIAV functions in equine and canine cells but not in human cells. In this study, we present sequences of cyclins T1 from horse and dog and demonstrate that their N-terminal 300 residues rescue the transactivation of Tat from EIAV in human cells. Although human and equine cyclins T1 bind to this Tat, only the equine cyclin T1 supports the binding of Tat to TAR from EIAV. Finally, a reciprocal exchange of the valine for the leucine at position 29 in human and equine cyclins T1, respectively, renders the human cyclin T1 active and the equine cyclin T1 inactive for Tat transactivation from EIAV. Thus, the collaboration between a specific cyclin T1 and Tat for their high-affinity interaction with TAR is a common theme of lentiviral transactivation.

Amino Acid Sequence↗
PubMed1999

Interactions between Tat and TAR and human immunodeficiency virus replication are facilitated by human cyclin T1 but not cyclins T2a or T2b.

The transcriptional transactivator (Tat) from the human immunodeficiency virus (HIV) does not function efficiently in Chinese hamster ovary (CHO) cells. Only somatic cell hybrids between CHO and human cells and CHO cells containing human chromosome 12 (CHO12) support high levels of Tat transactivation. This restriction was mapped to interactions between Tat and TAR. Recently, human cyclin T1 was found to increase the binding of Tat to TAR and levels of Tat transactivation in rodent cells. By combining individually with CDK9, cyclin T1 or related cyclins T2a and T2b form distinct positive transcription elongation factor b (P-TEFb) complexes. In this report, we found that of these three cyclins, only cyclin T1 is encoded on human chromosome 12 and is responsible for its effects in CHO cells. Moreover, only human cyclin T1, not mouse cyclin T1 or human cyclins T2a or T2b, supported interactions between Tat and TAR in vitro. Finally, after introducing appropriate receptors and human cyclin T1 into CHO cells, they became permissive for infection by and replication of HIV.

Animals↗
PubMed1999

Interactions between human cyclin T, Tat, and the transactivation response element (TAR) are disrupted by a cysteine to tyrosine substitution found in mouse cyclin T.

The transcriptional transactivator Tat from HIV binds to the transactivation response element (TAR) RNA to increase rates of elongation of viral transcription. Human cyclin T supports these interactions between Tat and TAR. In this study, we report the sequence of mouse cyclin T and identify the residues from positions 1 to 281 in human cyclin T that bind to Tat and TAR. Mouse cyclin T binds to Tat weakly and is unable to facilitate interactions between Tat and TAR. Reciprocal exchanges of the cysteine and tyrosine at position 261 in human and mouse cyclin T proteins also render human cyclin T inactive and mouse cyclin T active. These findings reveal the molecular basis for the restriction of Tat transactivation in rodent cells.

Amino Acid Sequence↗
PubMed1998

Rabbit cells expressing human CD4 and human CCR5 are highly permissive for human immunodeficiency virus type 1 infection.

To evaluate the feasibility of using transgenic rabbits expressing CCR5 and CD4 as a small-animal model of human immunodeficiency virus type 1 (HIV) disease, we examined whether the expression of the human chemokine receptor (CCR5) and human CD4 would render a rabbit cell line (SIRC) permissive to HIV replication. Histologically, SIRC cells expressing CD4 and CCR5 formed multinucleated cells (syncytia) upon exposure to BaL, a macrophagetropic strain of HIV that uses CCR5 for cell entry. Intracellular viral capsid p24 staining showed abundant viral gene expression in BaL-infected SIRC cells expressing CD4 and CCR5. In contrast, neither SIRC cells expressing CD4 alone nor murine 3T3 cells expressing CCR5 and CD4 exhibited significant expression of p24. These stably transfected rabbit cells were also highly permissive for the production of virions upon infection by two other CCR5-dependent strains (JR-CSF and YU-2) but not by a CXCR4-dependent strain (NL4-3). The functional integrity of these virions was demonstrated by the successful infection of human peripheral blood mononuclear cells (PBMC) with viral stocks prepared from these transfected rabbit cells. Furthermore, primary rabbit PBMC were found to be permissive for production of infectious virions after circumventing the cellular entry step. These results suggest that a transgenic rabbit model for the study of HIV disease may be feasible.

Animals↗
PubMed1997

Implant overdenture with a tapered bar and Lew passive attachments: clinical report.

Although the Lew attachment was originally developed in 1977 to provide retention for overdentures fabricated in conjunction with subperiosteal implants, these attachments can be used with other types of implants. A case is presented describing the use of Lew attachments with a tapered bar and seven root form implants.

Dental Casting Technique↗
PubMed1987

An open randomised comparison of ofloxacin and doxycycline in lower respiratory tract infections.

The efficacy and tolerance of ofloxacin and doxycycline were compared in patients with lower respiratory tract infections. Doses used were 200 or 400mg twice daily for ofloxacin and 100mg twice daily for doxycycline. Of 230 patients treated, 219 could be assessed for effectiveness. 88 patients were treated for exacerbations of chronic bronchitis and 131 for pneumonia. Clinical cure was achieved in 18 of 52 patients with bronchitis treated with ofloxacin. Improvement occurred in 29 and failure in 5. In the doxycycline-treated bronchitis group 11 of 36 patients were cured, 22 improved and 1 failure occurred. Of 62 patients with pneumonia who were administered ofloxacin, 34 were cured, 26 improved and treatment failed in 2. In the doxycycline-treated group of patients with pneumonia 39 of 69 were cured, 23 improved and 7 failed to respond. Two patients experienced adverse effects during ofloxacin treatment and 7 while receiving doxycycline.

Anti-Infective Agents↗
PubMed1984

A neurological disorders workshop for school nurses.

The Neurological Disorders Workshop was a continuing education experience for school nurses in central Vermont. It examined neurologically-related clinical problems commonly encountered by school nurses such as neurological screening, mental retardation, seizure disorders, motor system disorders, attention and behavior disorders, diagnostic screening tools, and referral sources. The six-day workshop (five consecutive days plus a follow up four months later) used didactic presentations, demonstrations, and practicum experiences. After the workshop, written evaluations were conducted.

Clinical Competence↗
PubMed1976

Neonatal intensive care in community hospitals and remote areas. The problems and a possible solution.

This has been a brief summary of the problems emerging as more community hospitals develop neonatal intensive care, analyzing their possible origins and significance. A description of one solution to the problem has been given, exemplified by an outreach program from the University of California, San Diego, and University Hospital, San Diego, with the community of Las Vegas, Nevada. We feel strongly that the responsibilities of medical schools toward community hospitals and toward regionalization in isolated communities should be unique and are not covered by usual regulations or traditional concepts of regionalization.

Education, Continuing↗
PubMedDate not supplied

Genitourinary malformation with calcified intraluminal meconium and pulmonary hypoplasia.

Calcified intraluminal meconium is a rare finding in newborn infants that is often associated with communication between the urinary and gastrointestinal tracts. Frequently such infants die because of respiratory problems. An illustrative case is presented, and pulmonary hypoplasia is suggested as an etiology of the respiratory difficulties observed.

Calcinosis↗