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Biomedical subjects

A Johnsson

Publications and source records attributed to A Johnsson.

At least 91 records · Page 5Linked to original sources
PubMed1976

Depression and daily temperature. A long-term study.

In a long-term observation of a manic-depressive female patient, three depressive episodes and two intervals without complaints were studied. During this period, the oral temperature was measured every 3 h. The temperature values were compared with a self-rating scale of the patient. The oral temperature showed a different pattern on the depressive days as compared with the interval days. The average temperature values were higher on depressive days. During the depression, changes were found in the daily temperature rhythm which resulted in a temperature maximum earlier in the day. The changes can be explained as indicating a desynchronization phenomenon of the circadian rhythms.

Adult↗
PubMedDate not supplied

Platelet-derived growth factor is structurally related to the putative transforming protein p28sis of simian sarcoma virus.

A partial amino acid sequence of human platelet-derived growth factor, the major mitogen in serum for cells of mesenchymal origin, has been determined. A region of 104 contiguous amino acids shows virtual identity with the predicted sequence of p28sis, the putative transforming protein of simian sarcoma virus (SSV). This similarity suggests a mechanism for transformation by SSV and other agents, involving expression of growth factors.

Amino Acid Sequence↗
PubMedDate not supplied

Antibodies against platelet-derived growth factor inhibit acute transformation by simian sarcoma virus.

A clue to the molecular mechanism of neoplastic transformation was provided by the finding of a near identity in amino-acid sequence between the platelet-derived growth factor (PDGF) B-chain and a region in the transforming protein, p28sis, of simian sarcoma virus (SSV), an agent that causes sarcomas and gliomas in experimental animals. This finding infers a direct link between the molecular biology of normal mitogenesis and oncogenesis since it suggests that the transforming activity of SSV is caused by a growth factor. Although PDGF agonist activity has been isolated from conditioned medium of SSV-transformed cells, it is not clear whether infection of responsive cells by SSV leads solely to autocrine stimulation of growth by a secreted PDGF-like factor or whether other, possibly intracellular, activities of p28sis or its processed products contribute to the transformation. To distinguish between these possibilities, we have studied the effect of anti-PDGF antibodies on acute SSV-transformation, and report here that these antibodies inhibit both proliferation and SSV-induced morphological changes in human diploid fibroblasts.

Antibodies↗
PubMedDate not supplied

A human osteosarcoma cell line secretes a growth factor structurally related to a homodimer of PDGF A-chains.

Platelet-derived growth factor (PDGF), as purified from fresh human platelets, is a protein of relative molecular mass (Mr) 30,000 composed of two disulphide-linked subunit chains of similar size, named A and B (ref. 1). The dimer structure of PDGRF seems to be important for its biological effects, as reduction irreversibly inactivates the factor; it is not known, however, whether PDGF exists as a heterodimer or as a mixture of homodimers. Amino-acid sequence analysis has revealed that the A- and B-chains of human PDGF are related to each other, and that the B-chain is almost identical to part of the v-sis gene product of simian sarcoma virus (SSV). There is experimental evidence that a PDGF-like protein is indeed operational in SSV-induced transformation and the biologically active v-sis product is probably structurally similar to a putative dimer of PDGF B-chains. PDGF-like growth factors and/or a 4.2-kilobase (kb) c-sis transcript are present in several transformed mammalian cell lines and in certain nontransformed cells; cloned c-sis complementary DNA from human T cells transformed with human T-lymphotropic virus (HTLV) or from human endothelial cells contains the coding sequence for a putative PDGF B-chain precursor, but apparently lacks PDGF A-chain sequences. We have previously partially purified and characterized a PDGF-like growth factor from U-2 OS cells (osteosarcoma-derived growth factor, ODGF) and shown that this factor has structural, functional and immunological characteristics in common with PDGF. We describe here a procedure for the preparation of homogeneous ODGF, and provide evidence that this factor, which binds to the PDGF receptor, has a structure similar to a homodimer of PDGF A-chains.

Cell Line↗
PubMedDate not supplied

cDNA sequence and chromosomal localization of human platelet-derived growth factor A-chain and its expression in tumour cell lines.

The amino-acid sequence of the precursor of the human tumour cell line-derived platelet-derived growth factor (PDGF) A-chain has been deduced from complementary DNA clones and the gene localized to chromosome 7. The protein shows extensive homology to the PDGF B-chain precursor. Expression of the PDGF A-chain gene is independent of that of the PDGF B-chain in a number of human tumour cell lines, and secretion of a PDGF-like growth factor of relative molecular mass 31,000 correlates with expression of A- but not B-chain messenger RNA.

Base Sequence↗
PubMedDate not supplied

Gastrointestinal damage induced by cytostatic treatment does not affect the bioavailability of co-trimoxazole.

Twelve lymphoma patients received prophylaxis with co-trimoxazole during cytostatic treatment according to the MACOP-B regimen with cyclophosphamide, doxorubicin, vincristine, methotrexate, bleomycin, folinic acid and prednisone. Gastrointestinal mucosal damage from cytostatic treatment was estimated by WHO toxicity scores. No correlation was found between the degree of gastrointestinal damage and the presumed bioavailability of co-trimoxazole as estimated from serum levels of trimethoprim and sulphamethoxazole. The serum concentrations were above the minimum inhibitory concentration for Escherichia coli, Staphylococcus aureus and coagulase-negative staphylococci irrespective of the degree of toxicity. There is no apparent reason to change the dosing regimen of prophylactic co-trimoxazole when there is clinical evidence of damage to the gastrointestinal mucosa induced by chemotherapy.

Adolescent↗
PubMedDate not supplied

Free-running human circadian rhythms in Svalbard.

The body temperature, activity-rest time, electrolytes of urine samples and mood was measured in two persons a 19 day period under continuous light conditions in the arctic (vicinity of Ny Alesund, Svalbard-Spitsbergen). For temperature recording a new thermoprobe and a portable printer was used. Possible week Zeitgeber of the 24 hour day did not synchronize the circadian system, since circadian rhythms of about 26 hours were found. These results open up the possibility to study effects of drugs on the circadian system of humans under Svalbard conditions.

Adult↗
PubMedDate not supplied

Influence of lithium ions on human circadian rhythms.

Lithium carbonate lengthens the circadian period of body temperature and sleep-wakefulness in humans under temporal isolation (arctic conditions in Svalbard, 79 degrees N) in two out of four groups.

Adult↗
PubMedDate not supplied

Photodestruction of Propionibacterium acnes porphyrins.

The fluorescence spectra of colonies of Propionibacterium acnes were studied under various experimental conditions. The spectra contained peaks at 580 nm and 620 nm. These bands were due to two different components; the 580 nm component was likely to be a metalloporphyrin, and there are indications that the 620 nm component could be a coproporphyrin. The 580 nm fluorescence was destroyed by the combined action of light and oxygen (no destruction under strict anaerobic conditions). A dark period interrupting the bleaching light stopped the destruction of this component for the time of the dark period. The initial production of the 620 nm component was due to the oxygen exposure. Upon light irradiation this component was later destroyed by the combined action of oxygen and light.

Anaerobiosis↗
PubMedDate not supplied

Phase response curve for the ultradian rhythm of the lateral leaflets of Desmodium gyrans using DC current pulses.

In the present study the leaf movement rhythm was perturbed by the application of DC current pulses (15 microA, 10 seconds, voltage applied: 10 V) to the upper part of the pulvinus, passing through the pulvinus and its stalk. The pulses were applied at four different positions of the leaflets: when the leaves were at the lowermost position, when moving up, at the uppermost position and when moving down. The pre-perturbed and the post-perturbed rhythms were compared. We found that the rhythms were shifted in phase and the phase shifts observed at the four different positions of the leaflets were significantly different in magnitude as well as direction. Furthermore, we could also observe phase advances, which is in contrast to an earlier finding. A phase response curve (PRC) was constructed to illustrate the sensitivity of the oscillating leaflet system to DC pulses. Substantial delays of about 50 s (as compared to the period of about 200 s) were obtained when pulses were administered at the lowermost position and when leaflet were moving upwards, while advances or no phase shifts were recorded in the uppermost position and when leaflet were moving down respectively.

Activity Cycles↗