PubMed Health⌕ Search

Biomedical subjects

C Persson

Publications and source records attributed to C Persson.

68 records · Page 4Linked to original sources
PubMed1990

Control of replication of plasmid R1: formation of an initial transient complex is rate-limiting for antisense RNA--target RNA pairing.

The replication frequency of plasmid R1 is determined by the availability of the initiator protein RepA. Synthesis of RepA is negatively controlled by an antisense RNA, CopA, which forms a duplex with the upstream region of the RepA mRNA, CopT. We have previously shown that the in vitro formation of the CopA-CopT duplex follows second-order kinetics and occurs in at least two steps. The first step is the formation of a transient (kissing) complex, which is subsequently converted to a persistent duplex. Here, we investigate the details of the reaction scheme and determine the rate constants of the pathway from the free RNAs to the complete duplex. Using a shortened CopA RNA (CopI) we have been able to determine the association and dissociation rate constants (k1,k-1) for the kissing complex (which are inferred to be the same for CopI-T and CopA-T), and measured the hybridization rate constant k2 (for CopA-T k2 is at least 1000-fold greater than for CopI-T). The analysis of CopA derivatives of mutant and wild-type origin shows that the rate of formation of the kissing complex is rate-limiting for the overall pairing reaction between CopA and CopT, both in vitro and in vivo. The biological implications of the kinetically irreversible RNA-RNA binding reaction scheme are discussed.

DNA Mutational Analysis↗
PubMed1989

Correlation of altered penile ultrastructure with clinical arterial evaluation.

We investigated the ultrastructural changes in the penile erectile tissue from 32 consecutive patients who underwent penile prosthesis implantation. Because most of the patients had undergone papaverine injection with or without duplex ultrasonography, we compared these results with the electron microscopic findings. In patients with a good arterial response and full erection after papaverine injection the ultrastructural findings were similar to those reported in normal men. In patients with moderate arterial disease a distinct increase in mitochondria with aggregation and cytoplasmic vacuolization in smooth muscle cells was noted. These findings could be interpreted as an active cellular attempt to respond to the altered environmental and nutritive situation. In patients with severe arterial insufficiency the cellular structure was markedly altered, the number of intracavernous smooth muscle cells was reduced and the density of the connective tissue separating individual cells was increased. These changes in the smooth muscle cells consisted of contour irregularity with fragmentation and loss of the basal lamina. The cytoplasm was largely devoid of contractile elements. The nuclei tended to be pleomorphic with unevenly distributed chromatin. The endothelium was also altered significantly in this group. A careful clinical evaluation of penile arterial function should be performed in all patients undergoing penile arterial or venous corrective surgery. If doubt remains, a penile biopsy may be indicated.

Adult↗
PubMed1988

Translational control by antisense RNA in control of plasmid replication.

Control of replication of plasmids involves two processes: measurement of the copy number of the plasmid and adjustment of the replication frequency accordingly. For both these processes IncFII plasmids use an antisense RNA (CopA RNA) that forms a duplex with the upstream region (CopT) of the mRNA of the rate-limiting RepA protein. The kinetics of duplex formation was measured in vitro for the wild type and for a cop mutant plasmid; the mutant showed a reduction in the second-order rate constant for the formation of the RNA duplex and a similar increase in copy number. Hence, the kinetics of duplex formation and the concentration of CopA RNA determines the copy number of the plasmid.

Base Sequence↗
PubMed1988

Control of replication of plasmid R1: kinetics of in vitro interaction between the antisense RNA, CopA, and its target, CopT.

The frequency of replication of IncFII plasmids is regulated by the availability of a rate-limiting protein, RepA. This protein acts to promote initiation of replication and its synthesis is negatively controlled both at the transcriptional and translational level. The translational control is exerted by the binding of a small antisense RNA, CopA RNA, to its target, CopT, which is located in the leader region of the RepA mRNA. As a consequence, formation of RepA is inhibited. Here we demonstrate the binding of CopA RNA to CopT RNA in vitro; the rate constant of binding was determined to be approximately 1 X 10(6) M-1 s-1 at 37 degrees C. We have also shown that in vitro synthesized RepA mRNA molecules differing in length, but which contain the whole CopT region, are able to bind CopA RNA with similar rates. Analysis of the binding of CopA/CopT molecules derived from a copy-number mutant plasmid showed that the effect of the mutation on the rate of in vitro binding correlates well with its phenotypic effect in vivo, i.e. the binding rate constant is lowered in proportion to the increase in copy number. Likewise, the result of an in vitro incompatibility test is in agreement with in vivo data.

DNA Replication↗
PubMed1986

Control of replication of the broad host range plasmid RSF1010: the incompatibility determinant consists of directly repeated DNA sequences.

A 500 bp DNA fragment located in the vicinity of the origin of replication of plasmid RSF1010 was cloned into the plasmid vector pBR322 and shown to exhibit incompatibility against parental RSF1010. The rightmost region of this fragment contains three perfect 20 bp direct repeats and a fourth half-repeat of 11 bp, as shown by DNA sequencing. Deletion of the four repeats from the cloned fragment resulted in complete loss of incompatibility whereas partial deletion of the repeated sequence resulted in a concurrent decrease in the expression of incompatibility. We conclude that the incompatibility determinant of RSF1010 is defined by the four repeats and also that the incompatibility expressed is not very strong, since the presence of about 1.5 times as many copies of the repeated sequence as are normally in a cell does not cause a total switch off of RSF1010 replication, but only a 40% reduction in the rate of replication.

DNA Replication↗
PubMed1986

Peak expiratory flow and risk of cardiovascular disease and death. A 12-year follow-up of participants in the population study of women in Gothenburg, Sweden.

A longitudinal population study of 1,462 women, aged 38-60 years at entry, was begun in Gothenburg, Sweden, in 1968-1969. This paper deals with the first 12-year follow-up period. In univariate analysis, peak expiratory flow showed a significant negative correlation with the 12-year incidences of myocardial infarction, electrocardiographic changes suggesting ischemic heart disease, stroke, and death. The association with incidence of myocardial infarction, stroke, and death remained in multivariate analysis, and was independent of age, body height, body mass index, adipose tissue distribution, chest deformity, history of pulmonary disease, smoking habit, serum cholesterol concentration, serum triglyceride concentration, systolic blood pressure, diabetes, and physical activity. The findings indicate that measuring peak expiratory flow is a simple procedure to identify women with an increased risk of cardiovascular disease or death. It seems urgent to find out what preventive measures might be taken as a consequence of these observations.

Adult↗
PubMed1986

[Urinary retention in herpes zoster].

We report on 4 cases of transient neurogenic dysfunction of the urinary bladder caused by herpes zoster. All patients noticed a slow urinary stream leading to complete urinary retention and loss of sensation following the vesicular stage of herpes zoster, necessitating the insertion of a suprapubic tube. Urodynamic evaluations revealed a detrusor acontractility, cystoscopic findings included a unilateral cystitis. Symptoms and residual urine spontaneously disappeared after 2 to 3 weeks. The cause is a sacral meningo-radiculitis with herpes zoster virus leading to a transient neuromotoric paralysis of the urinary bladder.

Cystoscopy↗
PubMed1986

[Neurotherapy of the hyperactive bladder].

Results in the treatment of non-neurogenic bladder hyperactivity are unsatisfactory. However, the first promising results from neurostimulation and our own findings in the neuroanatomy and neurophysiology of the lower urinary tract have led us to consider peripheral neurostimulation of the S2 - dorsal root or dorsal nerve of the penis for treating patients with hyperactive bladder dysfunction. We report on the first 14 cases treated by peripheral neurostimulation and S2-dorsal root blockade with local anesthesia for bladder hyperactivity. The bladder function became normal, and the bladder capacity increased up to 400% under neurotherapy. The methods, results and complications are discussed.

Adult↗
PubMed1986

[Ileocystodynamics: urodynamic studies of the continent ileal bladder].

The continent ileal bladder represents a combination of the Kock-Pouch and enterocystoplasty (Couvelaire-Camey): a continent intestinal urinary reservoir with antirefluxive nipple-ureteroileostomy and continence providing ileourethrostomy. Urodynamic investigations demonstrate the time dependent increase of maximal capacity and compliance reaching "normal"-bladder values in comparison to corresponding age groups within 4 months. The continent ileal bladder meets all requirements for bladder substitution including low-pressure reservoir function with reflux prevention, maintained continence and controlled voiding per viam naturalem.

Compliance↗