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J Freitag

Publications and source records attributed to J Freitag.

At least 19 recordsLinked to original sources
PubMed2000

A novel high-pressure liquid-liquid extraction process for downstream processing in biotechnology: extraction of cardiac glycosides.

This investigation examines phase equilibrium phenomena that can be used to create two water-like solvents for liquid-liquid extraction in downstream processing in biotechnology: a completely miscible, binary liquid mixture of water and a hydrophilic organic solvent (e. g., an alcohol) reveals a liquid phase split, when it is pressurized with a "near-critical" gas (i.e., a substance which at ambient conditions is a gas, near its critical temperature). This phase split results in two hydrophilic liquid phases. Making use of this phenomenon in process development first requires research on the phase split phenomenon and, second, research on the feasibility of biomolecule extraction and separation. In this study, basic fluid phase equilibrium phenomena are briefly described. Then, experimental results are reported for the partitioning of small amounts of cardiac glycosides (digitoxin and digoxin) on coexisting liquid phases in the high-pressure, three-phase, vapor-liquid-liquid equilibrium of the ternary system of "near critical" CO(2) + water + 1-propanol, at 313 K and 333 K. Finally, a process for extraction and separation of the aforementioned glycosides by means of the high-pressure phase equilibrium phenomenon is discussed.

1-Propanol↗
PubMed2000

G protein betagamma complexes in circumvallate taste cells involved in bitter transduction.

G protein betagamma (Gbetagamma) complexes are considered to play an important role in second messenger signaling of phospholipase C (PLC). Monitoring the inositol 1,4,5-trisphosphate (IP(3)) response in circumvallate tissue homogenates upon stimulation with denatonium benzoate, it was demonstrated that a glutathione S-transferase-GRK3ct fusion protein-a Gbetagamma scavenger-attenuates the bitter tastant-induced second messenger reaction. Towards an identification of the Gbetagamma complex involved in rat bitter taste transduction, it was found that the G protein beta(3) subtype is specifically expressed in taste receptor cells of circumvallate papillae. Gbeta(3)-specific antibodies blocked the denatonium benzoate-induced IP(3) formation in a dose-dependent manner; the inhibitory effect was reversed by preincubation with the antigenic peptide. A less pronounced inhibition was observed using Gbeta(1)-specific antibodies. Analyzing individual taste cells by single cell reverse transcriptase-polymerase chain reaction approaches, overlapping expression patterns for PLCbeta(2), Galpha(gust), Gbeta(3) and Ggamma(3) could be demonstrated. Furthermore, the co-expression of all profiled signal transduction components in individual taste receptor cells could be detected. These data support the concept that the denatonium benzoate-induced IP(3) response is mediated by an activation of PLCbeta(2) via a Gbetagamma complex, possibly composed of Gbeta(3) as the predominant beta subunit and Ggamma(3), and imply that multiple second messenger pathways may exist in individual taste receptor cells.

Animals↗
PubMed1999

On the origin of the olfactory receptor family: receptor genes of the jawless fish (Lampetra fluviatilis).

In vertebrates, recognition of odorous compounds is based on a large repertoire of receptor subtypes encoded by a multigene family. Towards an understanding of the phylogenetic origin of the vertebrate olfactory receptor family, attempts have been made to identify related receptor genes in the river lampreys (Lampetra fluviatilis), which are descendants of the earliest craniates and living representatives of the most ancient vertebrates. Employing molecular cloning approaches led to the discovery of four genes encoding heptahelical receptors, which share only a rather low overall sequence identity but several of the characteristic structural hallmarks with vertebrate olfactory receptors. Furthermore, in situ hybridization studies demonstrated that the identified genes are expressed in chemosensory cells of the singular lamprey olfactory organ. Molecular phylogenetic analysis confirmed a close relationship of the lamprey receptors to vertebrate olfactory receptors and in addition demonstrated that olfactory genes of the agnathostomes diverged from the gnathostome receptor genes before those split into class I and class II receptors. The data indicate that the lamprey receptors represent the most ancient family of the hitherto identified vertebrate olfactory receptors.

Amino Acid Sequence↗
PubMed1999

Liposomal prostaglandin E1 (TLC C-53) in acute respiratory distress syndrome: a controlled, randomized, double-blind, multicenter clinical trial. TLC C-53 ARDS Study Group.

OBJECTIVE: To evaluate the safety and efficacy of an intravenous liposomal dispersion of prostaglandin E1 as TLC C-53 in the treatment of patients with acute respiratory distress syndrome (ARDS). DESIGN: Randomized, prospective, multicenter, double-blind, placebo-controlled, phase III clinical trial. SETTING: Forty-seven community and university-affiliated hospitals in the United States. PATIENTS: A total of 350 patients with ARDS were enrolled in this clinical trial. INTERVENTION: Patients were prospectively randomized in a 1:1 ratio to receive either liposomal prostaglandin E1 or placebo. The study drug was infused intravenously for 60 mins every 6 hrs for 7 days starting with a dosage of 0.15 microg/kg/hr. The dose was increased every 12 hrs until the maximal dose (3.6 microg/kg/hr) was attained or intolerance to further increases developed. Patients received standard aggressive medical/surgical care during the infusion period. OUTCOME MEASURES: The primary outcome measure was the time it took to wean the patient from the ventilator. Secondary end points included time to improvement of the PaO2/FIO2 ratio (defined as first PaO2/FIO2 > 300 mm Hg), day 28 mortality, ventilator dependence at day 8, changes in PaO2/FIO2, incidence of and time to development/resolution of organ failure other than ARDS. RESULTS: A total of 348 patients could be evaluated for efficacy. The distribution of variables at baseline describing gender, lung injury scores, Acute Physiology and Chronic Health Evaluation II scores, PaO2/FIO2, pulmonary compliance, and time from onset of ARDS or from institution of mechanical ventilation to the first dose of study drug was similar among patients in the liposomal prostaglandin E1 (n = 177) and the placebo (n = 171) treatment arms. There was no significant difference in the number of days to the discontinuation of ventilation in the liposomal prostaglandin E1 group compared with the placebo group (median number of days to off mechanical ventilation, 16.9 in patients receiving liposomal prostaglandin E1 and 19.6 in those administered placebo; p = .94). Similarly, mortality at day 28 was not significantly different in the two groups (day 28 mortality, 57 of 176 (32%) in the liposomal prostaglandin E1 group and 50 of 170 (29%) in patients receiving placebo; p = .55). In contrast, treatment with liposomal prostaglandin E1 was associated with a significantly shorter time to reach a PaO2/FIO2 ratio of >300 mm Hg (median number of days to reaching a PaO2/FIO2 ratio >300 mm Hg: 9.8 days in the liposomal prostaglandin E1 group and 13.7 days in patients receiving the placebo; p = .02). Among the subgroups examined, time to off mechanical ventilation was significantly reduced in patients who received at least 85% of a full dose (i.e., > 45.9 microg/kg) of liposomal prostaglandin E1 (median number of days to discontinuation of ventilation, 10.3 in the liposomal prostaglandin E1 group and 16.3 days in patients receiving placebo; p = .05). The overall incidence of serious adverse events was not significantly different in the liposomal prostaglandin E1 (40%) or placebo-treated (37%) groups. Drug-related adverse events of all kinds were reported in 69% of the patients receiving liposomal prostaglandin E1 compared with 33% of the placebo group, with hypotension and hypoxia (occurring in 52% and 24% of the liposomal prostaglandin E1-treated patients, respectively, and 17% and 5% of the placebo-treated patients, respectively) being noted most frequently. CONCLUSIONS: In the intent-to-treat population of patients with ARDS, treatment with liposomal prostaglandin E1 accelerated improvement in indexes of oxygenation but did not decrease the duration of mechanical ventilation and did not improve day 28 survival.

Adult↗
PubMed1999

Expression of olfactory receptors during development in Xenopus laevis.

A coordinated expression of tissue- and cell-specific genes during development is required to establish the complex functional organization of the vertebrate olfactory system. Owing to the unique features of its olfactory system and the well-characterized phases of its development, Xenopus laevis was chosen as a model organism to study the onset and the temporal and spatial patterns of expression of olfactory-specific genes. Using RT-PCR and in situ hybridization, it was found that expression of Xenopus olfactory marker protein and of class I receptors, which are thought to be responsible for the perception of water-soluble odorants, was detectable as early as stage 32, less than 2 days after fertilization. In contrast, expression of class II receptors, which are thought to recognize airborne odours, was not detected before stage 49, approximately 12 days after fertilization. The results indicate that the expression of olfactory receptors and marker protein is governed by temporally regulated cues during development.

Animals↗
PubMed1998

Olfactory receptors in aquatic and terrestrial vertebrates.

In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the 'living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family.

Animals↗
PubMed1998

Identification of a phospholipase C beta subtype in rat taste cells.

From rat circumvallate papillae a novel phospholipase C (PLC) subtype has been cloned and identified as most closely related to human PLC beta2. The corresponding mRNA was only detected in sensory lingual tissue but not in non-taste lingual tissue or any other tissues examined by Northern blot analysis. In situ hybridization revealed that a subset of taste receptor cells of circumvallate papillae was specifically labeled. A functional involvement of this PLC beta subtype in taste signal transduction emerged from biochemical analysis monitoring the second messenger response in circumvallate preparations induced by denatonium benzoate. This bitter agent elicited a rapid and transient increase of the inositol 1,4,5-trisphosphate level; this response was blocked by U73122, a potent inhibitor of PLC, and by PLC beta2-specific antibodies. These data indicate that a phospholipase C beta2 isoform mediates a denatonium benzoate-induced second messenger response of taste sensory cells in the circumvallate papillae.

Amino Acid Sequence↗
PubMed1995

Malignant chiasmal glioma: a rare cause of rapid visual loss.

The clinical, neuroradiological, and histological findings of an adult patient suffering from malignant optic glioma is reported. Rapid visual deterioration was misdiagnosed for several months until biopsy confirmed the tumor. The patient died despite radiation therapy nine months after first symptoms. Our presentation will focus on the problems of diagnosing and establishing therapeutic procedures in this rare malignant neoplasm.

Brain Neoplasms↗
PubMed1995

Two classes of olfactory receptors in Xenopus laevis.

Xenopus laevis possess a gene repertoire encoding two distinct classes of olfactory receptors: one class related to receptors of fish and one class similar to receptors of mammals. Sequence comparison indicates that the fish-like receptors represent closely related members of only two subfamilies, whereas mammalian-like receptors are more distantly related, most of them representing a different subfamily. The fish-like receptor genes are exclusively expressed in the lateral diverticulum of the frog's nose, specialized for detecting water-soluble odorants, whereas mammalian-like receptors are expressed in sensory neurons of the main diverticulum, responsible for the reception of volatile odors.

Amino Acid Sequence↗
PubMed1994

A dose-ranging study of the efficacy and safety of azelastine nasal spray in the treatment of seasonal allergic rhinitis with an acute model.

BACKGROUND: Oral azelastine, a nonsteroidal antiinflammatory respiratory investigational drug has demonstrated activity in the treatment of allergic rhinitis and asthma with a good safety profile. METHODS: Azelastine nasal spray was compared with sustained-release oral chlorpheniramine maleate and placebo for efficacy and safety in the treatment of seasonal allergic rhinitis in a double-dummy, two-center, 2-day, double-blind, randomized, dose-ranging, parallel-groups, onset and duration of action study. Two hundred sixty-four subjects reported to an outdoor park on Saturday morning during the height of the fall pollen season and remained there for 8 hours that day and the next to ensure maximal exposure to seasonal aeroallergens. Symptom diary cards were collected hourly Saturday from 8:00 AM to 10:00 AM (baseline period). Subjects who had sufficient symptoms were randomized into five groups and received medication at 10:00 AM and 10:00 PM on Saturday and at 10:00 AM on Sunday: azelastine 0.1% (1 spray [0.12 mg] per nostril every 12 hours, 2 sprays per nostril every every 12 hours, or 2 sprays per nostril once daily), Chlor-Trimeton Repetabs (12 mg twice daily), or placebo (twice daily). Diary cards were completed hourly (11:00 AM to 4:00 PM) and at 6:00, 8:00, and 10:00 PM on Saturday and again hourly on Sunday (from 8:00 AM to 4:00 PM) to evaluate rhinitis symptoms and adverse events. RESULTS: Two hundred fifty-nine subjects completed the study. The groups that received 2 sprays of azelastine per nostril once and twice daily and the chlorpheniramine group had statistically significantly more improvement in total rhinitis symptoms than the placebo group without serious adverse events. CONCLUSIONS: This study supports a once to twice daily dosing regimen for 2 sprays of 0.1% azelastine in the acute treatment of allergic rhinitis with onset of action within 2 to 3 hours.

Administration, Intranasal↗
PubMed1994

Hypothalamic hamartomas: with special reference to gelastic epilepsy and surgery.

This study presents six patients with hypothalamic hamartomas diagnosed on the basis of magnetic resonance imaging. Histological confirmation was performed in three patients who underwent surgery. Immunohistological assays were used to determine the neurosecretory pattern. Four patients presented with epilepsy, including gelastic seizures. Other symptoms included behavioral abnormalities in four patients and precocious puberty and visual impairment in two patients. One patient presented associated developmental defects. Good results without morbidity were achieved with surgical resectioning in two patients with large hamartomas associated with behavioral abnormalities and gelastic epilepsy that was unresponsive to conventional medical treatment and in one patient with visual impairment. We propose a classification of the hypothalamic hamartomas based on topographical and clinical data obtained from 36 selected cases in the literature and six of our own cases. This classification should help to classify the various treatment methods and the surgical risks into four subgroups (Types la, lb, lla, and llb). We conclude that the surgical approach is a realistic alternative in certain cases, including large and broad-based Type llb hamartomas associated with gelastic epilepsy and behavioral disorders.

Adult↗
PubMed1993

Arrestin-subtypes in insect antennae.

Arrestin is supposed to be involved in uncoupling receptor-mediated second messenger cascades. Clones encoding proteins homologous to arrestin have been isolated from antennal cDNA libraries of Locusta migratoria and Heliothis virescens. Based on the size and several characteristic motifs, the two proteins are considered as members of different arrestin subfamilies. One of the subtypes, which has also been found in Drosophila, lacks the regulatory acidic C-terminal. The putative site of interaction with phosphorylated receptors, a cationic region in the primary structure, is conserved in all identified arrestins from locust to human.

Amino Acid Sequence↗
PubMed1992

[Vertebrobasilar ischemia. Value of Doppler ultrasound in the acute phase].

We prospectively studied patients with acute vertebrobasilar ischaemia to assess the value of Doppler ultrasound compared to cerebral angiography during initial evaluation. Doppler ultrasound was diagnostic in 11 of 14 patients (79%). Transcranial ultrasonic examination yielded important information in addition to extracranial findings in 8 of 11 patients. Depending on the underlying vascular pathology, Doppler ultrasound proved to be a useful screening instrument to support acute management of vertebrobasilar ischaemia. With regard to clinical symptoms and ultrasonic findings, practical consequences for diagnostic evaluation are proposed.

Blood Flow Velocity↗
PubMed1991

[Association of arteriovenous and cavernous angioma of the head and neck area].

A 20-year-old man complained of pulse-synchronous noise in the ear and recurrent bleedings in the nose and throat region. From birth he had had an extensive haemangioma, black-blue with dark-red parts. It had been diagnosed as a cavernous haemangioma, part of a Sturge-Weber syndrome. An angiogram was performed before intended dermatological treatment of the disfiguring venous angioma. It demonstrated the capillary venous angioma (slow-flow angioma) in the lateral triangle of the neck, extending up to the skull base. In addition there was an arteriovenous angioma (high flow angioma) in the region of the clivus, which was supplied bilaterally largely by the ascending pharyngeal artery. The arteriovenous angioma also had connections to the outflow area of the capillary venous angioma. These findings and absence of ocular changes excluded Sturge-Weber syndrome. Because of the risk of life-threatening bleedings, the arteriovenous malformation was superselectively embolized by multiple injections of nonresorbable polyvinyl-alcohol particles via a microcatheter. This brought about the collapse of the cutaneous angiomatous spaces. This case demonstrates that external appearance indicating a capillary venous angioma is not reliable. Before treatment of this malformation a neuroradiological diagnosis should be undertaken.

Adult↗
PubMed1990

Selective cerebral intraarterial DSA. Complication rate and control of risk factors.

In 1095 patients 2770 brain supplying arteries have been studied by i.a.-DSA. Definitive neurological deficits occurred in 0.09%, transient deficits were observed in 0.45%. The reduced complication rate in comparison to former studies seems to be a continued effect of technical progress (DSA) and the use of new isoosmotic contrast media. In order to reduce the "training hospital effect" as to complication rate careful supervision of trainees is necessary. The average fluoroscopy time per vessel is proposed as an objective measure of the investigational skill of a neuroradiologist.

Adult↗
PubMed1990

[The value of diagnostic computerized tomography in tumor nephrectomy patients].

In 84 patients after nephrectomy due to renal cell carcinoma a computerized tomography was performed to evaluate local tumor recurrence. The findings are classified stage-dependent. Other metastatic lesions were found by conventional radiologic methods. Based on stage-dependent different occurrence of metastases or local recurrences recommendations are made to the use of computerized tomography in the follow-up of patients suffering from renal cell carcinoma after nephrectomy.

Adolescent↗