Biomedical subjects

F Friedrich

Publications and source records attributed to F Friedrich.

At least 19 recordsLinked to original sources

PubMed2002

Cloning and functional characterization of two glycine receptor alpha-subunits from the perch retina.

Glycine receptors are ligand-gated ion channel proteins mediating synaptic inhibition in the spinal cord, retina and brain of vertebrates. We have cloned and functionally characterized two glycine receptor alpha-subunits from the perch (Roccus americana) retina. Based on sequence homology with the mammalian counterparts, we termed these subunits alpha 1 and alpha 3. RT-PCR revealed the presence of both subunits in retina and brain, whereas alpha1 was predominant in spinal cord. A short splice variant of alpha1 was detected in the brain but not in the retina. Functional expression of the perch subunits in HEK-293 cells yielded robust glycine-gated currents sensitive to strychnine. The perch receptors displayed a high efficacy for taurine and GABA and thus differ from the mammalian counterparts. Because the retina is a rich source for taurine, this finding could be of physiological importance. The structural features of the ligand binding domain strongly support the notion of increased glycine/GABA discrimination in higher vertebrates.

Amino Acid Sequence↗

PubMed2001

Genomic characterization of wild-type measles viruses that circulated in different states in Brazil during the 1997 measles epidemic.

Despite the marked reduction in the incidence of measles in Brazil, a measles epidemic occurred in this country in 1997. The measles cases observed during this epidemic began to reappear in large numbers in São Paulo, and spread to Rio de Janeiro and other Brazilian states. In the present study molecular biology techniques were used for the detection and genomic characterization of measles viruses from clinical samples such as urine and nasopharyngeal secretions collected in the states of Rio de Janeiro, Minas Gerais and Paraná, during the 1997 epidemic. RT-PCR and nucleotide sequence analysis of part of the carboxyl-terminal region of the nucleoprotein gene of measles viruses obtained directly from clinical samples or from infected cell cultures during this epidemic classified all as wild-type of genotype D6. As the genotype D6 was identified in different Brazilian states, this study demonstrated that this genotype was circulating in Brazil during the 1997 epidemic.

Adult↗

PubMed2000

Recent measles viral activity in Uruguai: serological and genetic approaches.

In the summer 1999, a measles outbreak occurred in Uruguai. During this outbreak 58 cases were recorded, 36 of which were laboratory confirmed as positive for measles virus (MV) IgM. The cases occurred in touristic places (Montevideo and Maldonado) predominantly among health facilities and tourist service personnel. Urine specimens collected between days 1 and 4 after the onset of the rash from seven cases were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR with primers specific for the carboxyl-terminal region of the nucleoprotein (N) gene. Three of these specimens/cases were positive for MV. Sequencing of 300 nucleotides (nt) of PCR products corresponding to a part of the carboxyl-terminal region of the MV N gene detected in these specimens MV of D6 genotype. The same nucleotide sequences and the same genotype were also previously observed for MV isolates from the 1997 epidemic in Brazil and the 1998 epidemic in Argentina, demonstrating that the D6 genotype was, and may be still circulating in South America.

Adult↗

PubMed2000

Molecular evolution of oral poliovirus vaccine strains during multiplication in humans and possible implications for global eradication of poliovirus.

The oral poliovirus vaccine (OPV) has been effectively used in the control of poliomyelitis and in the eradication of wild polioviruses. Although there are many advantages in using attenuated OPV strains in the campaign to eradicate poliomyelitis, several studies have demonstrated that there are some disadvantages such as (a) excretion by vaccines of OPV-derived polioviruses with genomic modifications known to increase the neurovirulence, (b) appearance of vaccine-associated paralytic poliomyelitis (VAPP) and other adverse effects in vaccinees, (c) occurrence of persistent infections caused by OPV-derived strains in immunodeficient patients with VAPP, (d) transmission of OPV-derived polioviruses to susceptible individuals which develop VAPP, and (e) detection of OPV-derived polioviruses in the environment, which could be a source of infection for humans in the future. Different studies indicate that it is important to consider the possibility of persistent infections and excretion of OPV-derived polioviruses for long periods by humans, and also the survival in the environment of OPV-derived polioviruses excreted by humans, which could be transmitted and circulate in a non-immune population after stopping poliovirus vaccination. The findings reported here may have important implications for global poliomyelitis eradication initiative and indicate that surveillance of OPV-derived strains will also be important in the final step of eradication of poliomyelitis from the planet.

Animals↗

PubMed1998

Dynamics of surfactant release in alveolar type II cells.

Pulmonary surfactant, secreted via exocytosis of lamellar bodies (LB) by alveolar type II (AT II) cells, maintains low alveolar surface tension and is therefore essential for normal lung function. Here we describe real-time monitoring of exocytotic activity in these cells by visualizing and quantifying LB fusion with the plasma membrane (PM). Two approaches were used. First, fluorescence of LysoTracker Green DND-26 (LTG) in LB disappeared when the dye was released after exocytosis. Second, phospholipid staining by FM 1-43 resulted in bright fluorescence when this dye entered the LB through the fusion pore. Both processes were restricted to and colocalized with LB and occurred simultaneously. In AT II cells, FM 1-43 offered the unique advantage to independently define the moment and cellular location of single exocytotic events as well as the amount of material released, and to monitor its extracellular fate. Furthermore, both dyes could be used in combination with fura-2. The results indicate considerable diversity in the dynamics of LB exocytosis. In the majority of cells stimulated with ATP and isoproterenol, the first fusion of LB coincided with the rise of [Ca2+]i, but subsequent response of other LB in the same cell considerably outlasted this signal. In other cells, however, the onset of exocytosis was delayed by several minutes. After LB fusion, release of surfactant from LB into an aqueous solution was slow. In summary, stimulated exocytosis in AT II cells occurs at a much slower rate than in most other secretory cells but is still a more dynamic process than predicted from conventional measurements of surfactant released into cell supernatants.

Adenosine Triphosphate↗

PubMed1998

The effectiveness of intrauterine insemination in couples with sterility due to male infertility with and without a woman's hormone factor.

OBJECTIVE: To examine the efficacy of IUI on fecundity and baby-take-home rates in cases of infertility attributable to a male factor with and without a woman's hormone factor. DESIGN: Retrospective analysis. SETTING: Department of Gynecology and Obstetrics at the General Public Hospital, Horn, Austria. PATIENT(S): Seventy-eight long-standing involuntarily childless couples. INTERVENTION(S): After a follicular phase GnRH analog (buserelin) protocol with hMG stimulation of the woman and a Percoll gradient preparation and capacitation of the man's semen, an IUI was performed. MAIN OUTCOME MEASURE(S): Fecundity and baby-take-home rates. RESULT(S): One hundred nine inseminations were followed by 53 pregnancies (48.6%; 95% confidence intervals (CI) 38.9%-58.4%) and 38 deliveries (34.9%; 95% CI 26.0%-44.6%). Forty-nine children were born and 47 are alive (43.1%). CONCLUSION(S): Intrauterine insemination combined with buserelin gonadotropin stimulation, Percoll semen preparation, and sperm capacitation is a feasible solution to the problem of sterility attributable to a male factor with and without a woman's hormone factor.

Adolescent↗

PubMed1998

Neurologic complications associated with oral poliovirus vaccine and genomic variability of the vaccine strains after multiplication in humans.

The oral poliovirus vaccine (OPV) has been effectively used in the reduction and control of poliomyelitis cases on the planet. Despite several advantages of using the attenuated OPV strains, the rare occurrence of vaccine-associated paralytic poliomyelitis (VAPP) cases in vaccine recipients and their susceptible contacts is a disadvantage. Molecular biology studies of polioviruses isolated from stool and central nervous system (CNS) of patients with VAPP have confirmed the vaccine origin of the isolates and demonstrated genomic modifications known or suspected to increase the neurovirulence. Similar genomic modifications have also been identified in OPV-derived strains isolated from healthy vaccinees and healthy contacts, suggesting that host factors are also involved in the establishment of poliomyelitis. Other neurologic complications such as meningitis, encephalitis, convulsions, transverse myelitis and Guillain-Barré syndrome have also been rarely associated with the use of this vaccine. The characterization of polioviruses isolated from such cases has demonstrated their OPV origin.

Feces↗

PubMed1997

Nitric oxide donors inhibit spontaneous depolarizations by L-type Ca2+ currents in alveolar epithelial cells.

L2 cells, a cloned pneumocyte-derived cell line, express voltage-dependent L-type Ca2+ channels, causing transient depolarizing spikes of the membrane potential (Vm) [P. Dietl, T. Haller, B. Wirleitner, H. Völkl, F. Friedrich, and J. Striessing. Am. J. Physiol. 269 (Lung Cell. Mol. Physiol. 13): L873-L883, 1995]. In this study, we examined the effect of nitric oxide (NO)- and guanosine 3',5'-cyclic monophosphate (cGMP)-dependent cell signaling on the activity of L-type Ca2+ channels. Using conventional microelectrodes, spontaneous depolarizations (SD) of Vm by activation of these channels are regularly seen in the presence of 10 mM bath Sr2+. The NO donors sodium nitroprusside (SNP; 1 mM), 3-morpholinosydnonimine (SIN-1; 100 microM), as well as S-nitroso-N-acetyl-D,L-penicillamine (SNAP; 10 microM) caused a significant reduction of the frequency of Sr(2+)-induced SD. These effects were completely reversed by 6-anilino-5,8-quinolinequinone (10 microM), an inhibitor of the soluble guanylyl cyclase, and could be mimicked by 8-bromoguanosine 3'5'-cyclic monophosphate (8-BrcGMP; 100 microM). Perforated patch-clamp experiments revealed that 8-BrcGMP exerted a significant decrease of the depolarization-induced L-type Sr2+ current in the majority of tested cells. Consistent with the dependency of these NO-mediated effects on cGMP, incubation of L2 cells with SNP, SIN-1, and SNAP lead to a pronounced increase of cellular cGMP concentration. We conclude that the NO donors inhibit the activity of L-type Ca2+ channels in L2 cells via a cGMP-dependent pathway. In the alveoli, this might occur under conditions associated with the release of NO.

Aminoquinolines↗

PubMed1997

Rare adverse events associated with oral poliovirus vaccine in Brazil.

Oral poliovirus vaccine (OPV) developed by A. Sabin has been effectively used to control poliomyelitis in Brazil, and the last case with the isolation of a wild poliovirus strain occurred in March 1989. Although the vaccine controlled the circulation of wild strains and poliomyelitis cases associated with these strains were not detected during the last eight years, rare cases classified as vaccine-associated paralytic poliomyelitis (VAPP) have been detected. Molecular characterization studies of poliovirus strains isolated from VAPP cases and from healthy contacts have confirmed that the isolates are derived from the Sabin vaccine strains and also detected genomic modifications known or suspected to increase neurovirulence such as mutations and recombination. The molecular characterization of polioviruses isolated during the last eight years from paralysis cases classified as Guillain-Barré (GBS) syndrome and transverse myelitis (TM), and from facial paralysis (FP) cases also confirmed the vaccine origin of the strains and demonstrated mutations known to increase neurovirulence. Analysis of the epidemiologic data of these GBS, TM and FP cases demonstrated that in most of them the last OPV dose was given months or years before the onset of the disease and the isolation of the polioviruses. The temporal association between the isolation of these strains and the GBS, TM and FP suggested that the Sabin vaccine-derived poliovirus strains could also rarely trigger the diseases.

Brazil↗

PubMed1996

Two different store-operated Ca2+ entry pathways in MDCK cells.

Whole cell patch clamp experiments in conjunction with Fura-2 fluorescence microscopy were performed to study the mechanisms of 'store-operated' (capacitative) Ca2+ entry. In MDCK cells, depletion of inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ stores activates a store-operated cation current (SOCC) predominantly selective for Ca2+ than for Na+ or Mn2+ [Delles C., Haller T., Dietl P. A highly calcium-selective cation current activated by intracellular calcium release in MDCK cells. J Physiol 1995, 486: 557-569]. In the presence of extracellular Ca2+, thapsigargin (TG) stimulated both SOCC and a Ca(2+)-dependent K+ current (IK(Ca)), reflecting stimulation of store-operated Ca2+ entry. The Ca2+ entry blocker 1-[3-(4-methoxyphenyl) propoxyl]-1-(4-methoxyphenyl)-ethyl-1H-imidazole HCI (SK&F96365; 30 microM) did not inhibit SOCC. At the same concentration, it exerted a transient partial inhibition on IK(Ca) activated by TG-induced Ca2+ entry. It did, however, not directly inhibit IK(Ca). This was demonstrated by an unchanged relationship between the cytosolic Ca2+ concentration ([Ca2+]i) and IK(Ca) in experiments where [Ca2+]i was measured under whole cell patch clamp conditions and by a lacking effect of SK&F96365 on IK(Ca) prestimulated by a high 'clamped' [Ca2+]i. La3+ partially, but not directly, inhibited the TG-induced IK(Ca) at a concentration (10 microM) sufficient to entirely block SOCC. La3+ and SK&F96365 in combination exerted an additive reduction on the TG-induced whole cell conductance (G) and completely blocked IK(Ca) stimulated by TG. We conclude that two Ca2+ entry pathways with different pharmacological and biophysical properties are involved in 'store-operated' Ca2+ entry in MDCK cells.

Animals↗

PubMed1996

[Enzyme therapy in treatment of mastopathy. A randomized double-blind clinical study].

In this randomized double-blind clinical study the efficacy of an enzyme preparation (Wobenzym) was compared with hormone therapy (Lynestrenol) in 29 women with mastopathy. There was a significantly greater decrease in number of hardenings of the mammary gland after 2 months of enzyme therapy than Lynestrenol therapy: improvement in the former group was 100%, in the latter group 78.6%. No significant difference was observed regarding the numbers of lumps, or number and size of cysts, sensitivity to touch, feeling of tension, spontaneous pain, and pain on pressure. The efficacy of both medicines is valued as good. Wobenzym therapy was tolerated very well. No side effects appeared at all. Enzyme therapy is an alternative, low-risk therapy for the management of mastopathy, which does not interfere with the already upset hormonal balance of the patients.

Adult↗

PubMed1996

Poliovirus type 1 isolated from a vaccine-associated case of paralytic poliomyelitis in Brazil.

This study reports a type 1 poliovirus strain isolated in Brazil from a case classified as vaccine-associated paralytic poliomyelitis (VAPP). After serotyping of the viral isolate with hyperimmune equine sera, PCR and molecular hybridization techniques characterized the strain as P1/Sabin-derived. The isolate was partially sequenced to identify mutations at nucleotides 480, 525 and 6203, which are important for reversion of the P1/Sabin strain to neurovirulence. In a recent study, a P1/Sabin-derived strain isolated from the central nervous system of a VAPP case did not mutate at these positions, but maintained 480-G and 525-U (and 6203-C), suggesting that these mutations are not essential for the occurrence of disease (Georgescu et al., (1994), Journal of Virology, 68: 8089-8101). Although the Brazilian strain also maintained 480-G and 525-U (and 6203-C) and was isolated from the stool, the possibility that this isolate invaded the central nervous system after replicating in the gut, causing the paralysis, cannot be ruled out. This is the first report of a type 1 VAPP case in Brazil, although some cases caused by type 2 and type 3 strains have been described.

Brazil↗

PubMed1996

Type 2 poliovirus recombinants isolated from vaccine-associated cases and from healthy contacts in Brazil.

In a previous study (Friedrich et al., 1995b) P2/Sabin-derived strains isloated in Brazil from vaccine-associated paralytic poliomyelitis (VAPP) cases and from healthy contacts were analyzed for the presence of mutations at nucleotide (nt) 481 in the 5'-noncoding region (5'NCR) and at the codon of amino acid (aa) 143 of the capsid protein VP1, that are known to increase neurovirulence. In the present study a part of the 3Dpol-coding region of these strains was sequenced (3Dpol seq.) with the aim to find recombinant strains. In the 3Dpol seq., four out of ten strains isolated from VAPP cases turned out to be recombinants: one had 3Dpol seq. from the P1/Sabin strain, while the second had a part of 3Dpol seq. both from the P2/Sabin and P1/Sabin strains; the third and fourth recombinants had 3Dpol seq. from non-vaccine strains. The strains isolated from healthy contacts of the two VAPP cases, from which type 2 vaccine/non-vaccine recombinant strains were isolated, also consisted from recombinant genomes with the same nt sequences as those of the isolates from VAPP cases, confirming the transmission of P2/Sabin-derived recombinants. Comparison of the aa sequence of the viral RNA polymerase of the P2/Sabin strain with the predicted aa sequences of these recombinants in 3Dopl seq. demonstrated that an aa 69 (Asp-->Glu)) substitution was observed in most of the recombinant genomes, while an aa 113 (Thr-->Ser) substitution was observed in all the recombinant genomes. The possibility that the genomic recombination increased the neurovirulence of these strains cannot be excluded.

Amino Acid Sequence↗

PubMed1996

Genomic modifications in Sabin vaccine strains isolated from vaccination-associated cases, healthy contacts and healthy vaccinees.

The three attenuated strains developed by A.B. Sabin have been effectively used as an oral live poliovirus vaccine (OPV) to control poliomyelitis in many countries. Although rarely, vaccination-associated paralytic poliomyelitis (VAPP) cases occur with the type 2 and 3 strains, and less frequently with the type 1 strain. The greater number of attenuating mutations in the P1/Sabin strain is probably reflected in the higher safety of this strain in comparison to type 2 and 3 strains. For the P1/Sabin strain, many attenuating mutations were already identified in the 5'-non-coding region (5'NCR), in the capsid proteins coding region, in the 3Dpol coding region, and the 3'-non-coding region (3'NCR). For the P2/Sabin and P3/Sabin strains, one mutation in 5'NCR and another in the capsid proteins coding region have been demonstrated to be important determinations of attenuation, although it has been suggested that other mutations may also have some effect, though minor. Although reverting mutations in attenuating determinants, suppressor mutations, mutations in antigenic sites and genomic recombination have been observed in strains isolated from VAPP cases, the observation of similar genomic modifications in strains isolated from healthy contacts and from healthy vaccinees has supported the view that host factors are also involved in the establishment of the disease. Reverting mutations at nucleotides (nt) 480 (G-->A), 481 (A-->G) and 472 (U-->C) for the P1/Sabin, P2/Sabin and P3/Sabin strains, respectively, have been detected in almost all strains isolated from VAPP cases and also from healthy vaccinees. Although the Sabin vaccine strains have been implicated in rare VAPP cases, recent studies have suggested that the vaccine strains could also trigger the Guillain-Barré syndrome (GBS), transverse myelitis (TM) and facial paralysis.

Animals↗

PubMed1995

The pulmonary epithelial cell line L 2 as a new model for an inducible nitric oxide synthase expressing distal airway epithelial cell.

Nitric oxide released in large amounts by inducible nitric oxide synthase (iNOS)-containing pulmonary cells plays an important role in many aspects of lung function in health and disease. The aim of this study was to establish a permanent non tumor-derived alveolar epithelial cell line that exhibits the typical characteristics of an iNOS-expressing cell. Therefore, the pulmonary epithelial cell line L2 (adult rat) was incubated with lipopolysaccharide derived from Escherichia coli (serotype 0111:B4) and different cytokines. The strongest effect on iNOS gene expression and nitric oxide release could be detected when L2 cells were coincubated with interferon-gamma + tumor necrosis factor-alpha. iNOS complementary DNA concentration was 25 amol/microliters at 9h, and nitrite/nitrate levels were 99.43 +/- 3.97 nmol/10(6) cells at 24h, respectively. Our results show that L2 cells can be regarded as an appropriate model for investigating iNOS gene expression and nitric oxide functions in alveolar epithelial cells.

Animals↗

PubMed1995

Activation of L-type Ca2+ channels after purinoceptor stimulation by ATP in an alveolar epithelial cell (L2).

In the alveolar epithelium, ATP increases the intracellular Ca2+ concentration ([Ca2+]i) and stimulates the secretion of surfactant. We investigated the effects of extracellular ATP on the membrane potential (Vm), the whole cell current, and [Ca2+]i in a cloned rat alveolar epithelial cell line (L2). In microelectrode experiments, ATP caused a sustained depolarization of Vm, resulting from the activation of cation and Cl- conductances, as revealed by ion replacements. The depolarizing phase of the Vm shift was superimposed by Ca(2+)-dependent depolarizing spikes. Spikes were also induced by depolarizing Vm with charybdotoxin or maitotoxin. Replacement of bath Ca2+ with Ba2+ or Sr2+ also evoked repetitive spikes. Ca2+ (Ba2+, Sr2+)-induced spikes were unaffected by pretreatment with ionomycin or thapsigargin. They were, however, completely abolished by (+)-isradipine (100 nM) and stimulated by BAY K 8644 (100 nM). Whole cell L-type Ca2+ (Ba2+, Sr2+) currents were similarly abolished by (+)-isradipine and enhanced by BAY K 8644. L-type Ca2+ channels were further confirmed by demonstrating high-affinity dihydropyridine receptors stereoselectively labeled by (+)-[3H]-isradipine, apparent dissociation constant < 1 nM. In fura 2 experiments, ATP evoked a transient elevation of [Ca2+]i in the absence of Ca2+ and a biphasic sustained elevation in the presence of Ca2+, indicating intracellular Ca2+ release and Ca2+ entry. The ATP-induced fura 2 signals were unaffected by (+)-isradipine. We conclude that in L2 cells, L-type Ca2+ channels are activated after purinoceptor stimulation by ATP. The overall [Ca2+]i response is, however, mediated by Ca2+ entry through and (+)-isradipine-insensitive mechanism and by intracellular Ca2+ release.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1995

Genomic characterization of type 1 Sabin-related polioviruses isolated in Brazil.

Eight strains of P1/Sabin-derived polioviruses isolated in Brazil from paralysis cases were analyzed. The serotypes of the viral isolates were identified by neutralization test with hyperimmune equine sera. The relationship of the isolates to the P1/Sabin strain was demonstrated by molecular hybridization and PCR. The isolates were partially sequenced with the objective of finding mutations at nucleotides (nt) 480 and 525 of the 5'-noncoding region (5' NCR) and at nt 6203 of the 3Dpol coding region (3Dpol), which are important for reversion towards neurovirulence. Four isolates from paralysis cases classified as Guillain Barré Syndrome (GBS; three with sequels) were analyzed; one presented G-->A (480) and C-->U (6203) mutations, one G-->A (480) mutation, one G-->A (480) and U-->C (525) mutations, and one did not mutate at the analyzed positions. Two isolates from transient facial paralysis cases were analyzed; one presented U-->C (525) mutation and the other G-->A (480) mutation. One isolate from a transient paralysis case classified as a neuroviral disease and one isolate from a paralysis case with sequels were analyzed and none mutated at the analyzed positions. Although the isolates may not be the causative agent of the disease, a temporal association between the isolation of the P1/Sabin-derived isolates and the disease was observed. The possibility that GBS and the facial paralysis were caused by these isolates could not be excluded.

Base Sequence↗

PubMed1995

Genomic characterization of type 3 polioviruses isolated from vaccine-associated poliomyelitis cases in Brazil.

Eight strains of P3/Sabin-related polioviruses were analyzed; four from persistent paralytic poliomyelitis cases classified as vaccine associated, one from a transient paralysis case classified as transverse myelitis, one from a transient paralysis case classified as Guillain-Barré syndrome, one from a transient facial paralysis case, and one from a healthy vaccine. The serotypes of the viral isolates were identified by the neutralization test with hyperimmune equine sera and the relationship of the isolates with the P3/Sabin strain was demonstrated by molecular hybridization of the viral RNA of the isolates with a P3/Sabin-specific probe. The P3/Sabin relationship was confirmed by PCR, using a pair of specific primers for P3/Sabin-related isolates. The available data indicate that a U-->C mutation at nucleotide 472 in the 5' noncoding region of the genome of the type 3 Sabin strain increases the neurovirulence of this strain and this mutation was observed in all type 3 isolates from vaccine-associated cases. These eight P3/Sabin-related isolates were partially sequenced in the 5' noncoding region and seven presented a U-->C mutation at nucleotide 472, except the isolate from a transient paralysis case classified as transverse myelitis, that maintained a U at nucleotide 472. Although this virus maintaining U at nucleotide 472 may not be the etiological agent of the disease, the possibility that the virus was the causative agent of the disease could not be ruled out.

Base Sequence↗