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O Fröhlich

Publications and source records attributed to O Fröhlich.

At least 19 recordsLinked to original sources
PubMed2001

Organization of the human gene encoding the epididymis-specific EP2 protein variants and its relationship to defensin genes.

The EP2 gene codes for at least nine message variants that are all specifically expressed in the epididymis. These variants putatively encode small secretory proteins that differ in their N- and C-termini, resulting in proteins that can have little or no sequence similarity to each other. We have isolated and sequenced the human EP2 gene to determine the molecular origin of these variants. The EP2 gene has two promoters, eight exons, and seven introns. Exons 3 and 6 encode protein sequences homologous to beta-defensins, a family of antimicrobial peptides. This sequence homology and the arrangement of promoters and defensin-encoding exons suggest that the EP2 gene originated from two ancestral beta-defensin genes arranged in tandem, each contributing a promoter and two exons encoding a leader sequence and a defensin peptide. The proposed evolutionary relationship between the EP2 gene and defensin genes is supported by the observation that the EP2 gene is located on chromosome 8p23 near the defensin gene cluster and is separated by 100 kilobases or less from DEFB2, the gene for beta-defensin-2. While the EP2 gene transcribes beta-defensin-like message variants, most of the known message variants code for nondefensin proteins or proteins containing only a partial defensin peptide sequence. We suggest that, during its evolution, the EP2 gene has acquired new functions that may be important for sperm maturation and/or storage in the epididymis.

Amino Acid Sequence↗
PubMed2001

Epididymal specificity and androgen regulation of rat EP2.

In primates, expression of the EP2 gene is androgen-dependent and epididymis-specific. EP2 mRNA expression was investigated in caput, corpus, and cauda regions of rat epididymis and in 15 other rat tissues. Polymerase chain reaction and Northern analyses showed that rat EP2 is expressed predominantly in the proximal caput epididymidis. EP2 mRNA expression was determined in proximal epididymides from castrated, sham-operated, and efferent duct-ligated rats. In castrated rats, EP2 mRNA decreased to <10% of that in sham-operated rats between Days 3 and 4 postcastration, demonstrating the androgen dependence of EP2 expression. In epididymides ligated unilaterally at the efferent ducts, EP2 mRNA levels were approximately equal to those in the unligated contralateral epididymides or in sham-operated rats, indicating that EP2 expression does not depend on testicular factors. In bilaterally castrated rats, immediate and delayed testosterone replacement showed the dependence of EP2 expression on circulating androgens. Injection of testosterone propionate (TP) on Days 0, 1, 2, and 3 postcastration maintained EP2 mRNA levels approximately equal to those in sham-operated rats. Starting at Day 4 postcastration, daily injection of TP for 7 days restored EP2 mRNA to approximately normal levels. These data indicate for the rat that EP2 is expressed specifically in the proximal caput epididymidis and that its expression depends on circulating androgens but not on testicular factors.

Androgens↗
PubMed2000

Pitfall of an internal control plasmid: response of Renilla luciferase (pRL-TK) plasmid to dihydrotestosterone and dexamethasone.

The thymidine kinase promoter-Renilla luciferase reporter plasmid (pRL-TK) is commonly used as a control for transfection efficiency in the Dual-Luciferase Reporter Assay System. While investigating hormone response elements in the promoters of the androgen-dependent, epididymis-specific EP2 gene, we found that hormone treatment affected the luciferase activity of pRL-TK-transfected cells. In African Green Monkey Kidney (CV-1) cells, cotransfected transiently with a hormone-responsive promoter-firefly luciferase reporter plasmid and with pRL-TK, Renilla luciferase activity increased in response to dihydrotestosterone (DHT) and decreased in response to dexamethasone (DEX). When a thromboxane synthase promoter Renilla luciferase plasmid (pRL-TS) was used in place of pRL-TK, Renilla luciferase activity remained constant in CV-1 cells treated with DHT but decreased in CV-1 cells treated with DEX. In transfection studies, internal control plasmid expression in response to treatment must be carefully monitored to ensure proper interpretation of normalized results.

Animals↗
PubMed1998

[Clinical and molecular biology studies of laryngeal papillomatosis].

BACKGROUND: Recurrent laryngeal papillomatosis is a benign neoplastic disease which is probably caused by but at least associated with the Human Papilloma Virus. It can be of significant importance for the affected patients because of its recurrent clinical course. A wide variety of therapeutic measures have been described including the surgical removal either with conventional instruments or laser. Malignancies developing from papillomas have been reported. PATIENTS: The clinical courses of all 95 patients who have been treated for laryngeal papillomatosis since 1960 were analysed retrospectively. The two most common forms of treatment, surgical removal either conventionally or with the use of the laser, were compared. "Hot-start" polymerase chain reaction and Southern blot hybridization were used to detect HPV-DNA. The case reports of all patients developing cancer of the larynx are included. RESULTS: Laryngeal papillomatosis is a disease of all ages, more often first diagnosed before age 10 or after age 30. Puberty had no effect on the clinical course. However, the rate of complications such as tracheostomy and glottic webs was significantly reduced after laser surgery. HPV-DNA was found in 10 of 11 samples. Squamous cell carcinoma subsequently developed in four cases, three of which occurred almost simultaneously and were therefore not included. CONCLUSION: The term juvenile laryngeal papillomatosis should be replaced by recurrent respiratory papillomatosis. The occurrence of squamous cell carcinomas in patients previously treated for papillomas underlines the need for repeated histological studies. The surgical treatment remains the mainstay in the management of laryngeal papillomatosis. The laser surgical technique is superior to conventional removal. Using the most sensitive and specific methods presently available, HPV-DNA can be detected in a large percentage of laryngeal papillomas.

Adolescent↗
PubMed1998

[Clinical and molecular biology studies of respiratory papillomatosis].

BACKGROUND: Recurrent laryngeal papillomatosis is a benign neoplastic disease which is probably caused by but at least associated with the human papillomavirus. It can be of significant importance for the affected patients because of its recurrent clinical course. A great variety of therapeutic measures has been described including the surgical removal either with conventional instruments or using the laser. Development of malignancies from papillomas have been reported. PATIENTS: The clinical courses of all 95 patients who have been treated for laryngeal papillomatosis since 1960 were analysed retrospectively. The two most common forms of treatment, surgical removal either conventionally or with the use of the laser, were compared. "Hot start" polymerase chain reaction and Southern blot hybridization were used to detect HPV DNA. The case reports of all patients developing cancer of the larynx are included. RESULTS: Laryngeal papillomatosis is a disease of all ages, more often first diagnosed in the first and fourth decade. Puberty had no effect on the clinical course. The different forms of treatment did not affect the rate of recurrence. However, the rate of complications such as tracheostomy and glottic webs was significantly reduced after laser surgery. Since the introduction of this new form of therapy no more tracheostomies had to be performed on these patients. HPV DNA was found in four of five samples (HPV 6:3, HPV 11:1). Squamous cell carcinoma subsequently developed in four cases, three of which occurred almost simultaneously and were therefore not included. CONCLUSION: The term juvenile laryngeal papillomatosis should be replaced by recurrent respiratory papillomatosis. One could then distinguish according to the age of onset, i.e., in children below the age of 16 years and in adolescents and adults older than 15 years. The occurrence of squamous cell carcinomas in patients previously treated for papillomas underlines the need for repeated histological studies. The surgical treatment remains the mainstay in the management of laryngeal papillomatosis. The laser surgical technique is superior to conventional removal. Using the at present most sensitive and specific methods HPV DNA can be detected in a large percentage of laryngeal papillomas.

Adolescent↗
PubMed1998

HE2/EP2, an androgen-dependent protein from the epididymis of the chimpanzee, Pan troglodytes.

A cDNA clone of chimpanzee EP2 was obtained from epididymal RNA by RT-PCR and was sequenced. Chimpanzee EP2 and human HE2 cDNA were > 99% identical and the proteins were 100% identical. The derived amino acid sequence of chimpanzee EP2 showed a consensus sequence for a leader peptide typical of secreted proteins. Northern blot analysis indicated that expression of the gene encoding chimpanzee EP2 is specific to the epididymis and not to other chimpanzee tissues examined. RT-PCR and northern blot analysis of epididymides recovered from an androgen deprived adult male chimpanzee showed that the expression of EP2 is androgen dependent.

Androgens↗
PubMed1996

Molecular cloning and characterization of EPI-1, the major protein in chimpanzee (Pan troglodytes) cauda epididymal fluid.

A 27-kDa glycoprotein comprises approximately 20% of the total protein in chimpanzee (Pan troglodytes) cauda epididymal fluid. Polyclonal antibodies generated against this glycoprotein react with 27- and 25-kDa components in chimpanzee cauda epididymal fluid and in human, gorilla, chimpanzee, and monkey seminal fluid. According to microsequencing, the 27- and 25-kDa components (chimpanzee EPI-1) are identical to the cloned putative human epididymal protein HE1. Screening of a chimpanzee epididymal cDNA library enabled isolation of a cDNA clone of chimpanzee EPI-1. On the cDNA level, chimpanzee EPI-1 and human HE1 are 99% identical. Northern analysis localized chimpanzee EPI-1 mRNA to the distal caput epididymidis. With EPI-1 primers, polymerase chain reaction of reverse-transcribed rhesus monkey (Macaca mulatta) epididymal RNA enabled isolation of a rhesus monkey EPI-1 cDNA clone. The derived amino acid sequence of rhesus monkey EPI-1 is identical to chimpanzee EPI-1 and to human HE1. Northern analysis localized rhesus monkey EPI-1 mRNA to the distal caput and the proximal corpus epididymidis. Northern analysis also showed that chimpanzee EPI-1 and rhesus monkey EPI-1 gene products are expressed specifically in the epididymis and not in any other tissue examined.

Amino Acid Sequence↗
PubMed1996

Recurrent laryngeal papillomatosis. Retrospective analysis of 95 patients and review of the literature.

BACKGROUND: Laryngeal papillomatosis is a benign neoplastic disease which is associated with and probably by the Human Papilloma Virus. It can be of significant importance for affected patients because of its recurrent clinical course. A great variety of therapeutic measures have been described including surgical removal either with conventional instruments or by using the laser. The aim of this study was to compare these two methods. PATIENTS: The clinical courses of all patients (53 male, 42 female) treated at the Dept. of Otolaryngology, Head and Neck Surgery, University of Kiel since 1960 were analysed retrospectively. The two most common forms of treatment, surgical removal either conventionally or with the use of the laser, were compared. RESULTS: Laryngeal papillomatosis is a disease of all ages, but often initially diagnosed in the first and fourth decade. In 25 cases the onset was before the age of 16. Puberty had no effect on the clinical course. A malignant degeneration was observed in four cases. Although the different forms of treatment did not affect the rate of recurrence, the rate of complications such as tracheostomy and glottic webs was significantly reduced after laser surgery. Since the introduction of this new form of therapy no further tracheostomies had to be performed on these patients. CONCLUSION: The term juvenile laryngeal papillomatosis should be replaced by recurrent respiratory papillomatosis. One could then make a distinction according to the age of onset, i.e. in children below the age of 16 years and in adolescents and adults older than 15 years. The occurrence of squamous cell carcinomas in patients previously treated for papillomas underlines the need for repeated histological studies. Our studies have shown that surgical treatment remains the mainstay in the management of laryngeal papillomatosis, with laser surgical technique being superior to conventional removal.

Adolescent↗
PubMed1993

Multiple carbohydrate moieties on the Na+/H+ exchanger.

Affinity-purified antibodies against the C-terminal region of the Na+/H+ exchanger (NHE-1) were used to analyse the carbohydrate moiety of the protein. The Na+/H+ exchanger in human placental brush-border membranes has an apparent molecular mass of 105 kDa. Incubation of intact or detergent-solubilized membranes with glycopeptidase F removed the carbohydrate moiety and increased the apparent mobility of the exchanger. Digestion with endoglycosidase-F caused a similar change in mobility, but endoglycosidase-H had no effect, suggesting that the placental Na+/H+ exchanger is a glycoprotein of the biantennary complex type. Removal of the carbohydrate moiety with glycopeptidase F had no effect on the ability of the protein to promote the exchange of Na+ for H+, and had no detectable effect on the sensitivity of the exchanger to trypsin. Limited digestion with glycopeptidase F and neuraminidase indicated the presence of two intermediate forms between the fully glycosylated and the deglycosylated protein. This suggests the presence of at least two, and possibly three, N-linked carbohydrate moieties.

Amidohydrolases↗
PubMed1992

Alpha 1-adrenergic stimulation of Na-H exchange in cardiac myocytes.

The activation of Na-H exchange in adult rat heart myocytes was characterized in response to a phorbol ester (phorbol 12-myristate 13-acetate) and an alpha 1-adrenergic agonist [6-fluoronorepinephrine (6F-NE)]. Transport activation was assessed by determining the initial rate with which intracellular pH (pHi) was returned from an acid pulse and by following changes in steady-state pHi; pHi was determined by a pH-sensitive fluorescent dye. Both agonists shifted the intracellular pH dependence of Na-H exchange by 0.10-0.15 pH units in the alkaline direction. This shift was prevented by the presence of sphingosine and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), inhibitors of protein kinase C. The agonists also alkalinized pHi at steady state. The alkalinization by 6F-NE was blocked by prazosin and H-7. This indicates that the adrenergic stimulation of cardiac Na-H exchange is mediated by an alpha 1-adrenergic mechanism and very likely involves the activation of protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Urinary concentrating ability in patients with Jk(a-b-) blood type who lack carrier-mediated urea transport.

Water homeostasis is regulated in large part by the proper operation of the urinary concentrating mechanism. In the renal inner medulla, urea recycling from the inner medullary collecting duct to the inner medullary interstitium is thought to be essential for the production of a concentrated urine; however, it has not been possible to test this hypothesis in humans. Recently, a unique combination of genetic abnormalities has been described: absence of Kidd blood group antigens and absence of carrier-mediated urea transport in erythrocytes. Because animal studies indicate a similarity between urea transport in red blood cells and the nephron, it was postulated that patients without the Kidd antigen might lack facilitated urea transport in their kidneys. Hence, their ability to concentrate urine maximally was measured. Current models of nephron function would predict that in the complete absence of urea transport, the maximal concentrating ability would be around 800 to 900 mosM/kg H2O. Two homozygous patients had a moderate decrease in maximal concentrating ability (UosM,max = 819 mosM/kg H2O); a heterozygote also had some limitation. These studies raise the possibility that the erythrocyte urea transporter and the kidney urea transporter are encoded by a single gene (detected by the mutational loss of the Kidd antigen) and that a lack of facilitated urea transport impairs urea recycling in the kidney and, hence, maximal urinary concentrating ability.

Adolescent↗
PubMed1991

Urea transport deficiency in Jk(a-b-) erythrocytes.

The activity of the urea transporter was determined in human erythrocytes of the Kidd blood type Jk(a-b-) by measuring unidirectional urea and thiourea fluxes in tracer flux experiments and urea net fluxes in light-scattering experiments. When compared with control cells, Jk(a-b-) cells exhibited diminished urea and thiourea fluxes and lacked the kinetic characteristics of mediated transport, suggesting that in these cells urea and thiourea moved only by simple diffusion through the lipid bilayer. Control experiments showed that anion, water, and ethylene glycol permeabilities were the same in Jk(a-b-) and control cells. These experiments thus demonstrate that Jk(a-b-) cells lack mediated urea transport and strongly support the notion that urea transport function is separate from the transport for anions, water, and ethylene glycol, probably because different proteins are responsible for these transport functions.

Biological Transport↗
PubMed1990

Anion transport in sickle red blood cells.

Anion transport in sickle cells (SS RBC) mediated by the band 3 membrane protein was evaluated by three different measures in both oxygenated and deoxygenated conditions and compared to normal red cells. First, Cl- self-exchange measured as 36Cl- efflux at 0 degrees C was normal in SS RBC in both Vmax and dependence on extracellular Cl- concentration. There was no effect of deoxygenation on either parameter. Second, stilbene-sensitive 35SO4=; SO4= exchange, measured at 37 degrees C where morphologic sickling occurred, was also unaffected by deoxygenation and was normal compared to normal red cells. Third, conductive Cl- flux was assessed by measuring the rates of Cl(-)-limited K+ efflux in valinomycin-treated cells at 37 degrees C. Both the stilbene-sensitive and insensitive components of net Cl- flux were similar in SS RBC and normal red cells, and were unaltered by morphologic sickling. Thus, despite dramatic alterations in cation transport in SS RBC and the demonstration of interaction between band 3 protein and sickle cell, anion transport functions appear to be normal in SS RBC and are unaffected by deoxygenation. These data suggest that the majority of the anion exchangers in SS RBC are functionally normal.

Anemia, Sickle Cell↗
PubMed1989

Antiporters.

Explore the source record for details and available documents.

Animals↗
PubMed1989

Na+-H+ exchange in isolated myocytes from adult rat heart.

The intracellular pH (pHi) in ventricular myocytes isolated from adult rat heart was measured in suspension using the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Steady-state pHi in bicarbonate-free media [extracellular pH (pHo) = 7.4] was 7.16 +/- 0.11 at 37 degrees C. With the use of the ammonium chloride prepulse technique, pHi was acidified, and the rate of return to resting pHi was determined. Initial rate analysis of the recovery was used to characterize the kinetics of proton net efflux via the Na+-H+ exchanger. At pHo = 7.4, proton extrusion was stimulated by extracellular sodium with a K1/2 = 58 +/- 16 mM and a maximal rate of recovery of 55 +/- 7 mmol/(1 cell H2O.min). Amiloride, which inhibited greater than 90% of the observed proton movements, was a competitive inhibitor with respect to Nao, with an inhibition constant of 3.5 microM. Proton net efflux was also inhibited by extracellular protons, with a maximal flux occurring above pHo = 8 and no net efflux occurring below pHo = 6.0. Efflux was stimulated by intracellular protons over a much narrower range (pHi = 6.6-7.1). This steep dependence indicates the involvement of at least one additional proton binding site besides the intracellular transport site, in accordance with the kinetic behavior observed in other cell systems.

Amiloride↗