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Biomedical subjects

G May

Publications and source records attributed to G May.

At least 91 records · Page 5Linked to original sources
PubMed1989

[PUVA treatment of organ transplants--experimental and clinical results].

The aim of the present study was to evaluate the influence of a pretreatment of the heart and kidney donor with the photosensitizer 8-methoxypsoralen plus ex vivo longwave ultraviolet irradiation of the graft (PUVA) on survival time and immunogenicity of rat heart and kidney allografts. PUVA pretreatment significantly prolonged the survival of these transplants in allogenic recipients. Furthermore, a synergistic effect with conventional immunosuppression (azathioprine, cyclosporine) was demonstrated. Immunohistological studies using monoclonal antibodies showed a significant reduction of MHC class II antigen expression in heart cryostat sections after PUVA treatment. In clinical kidney transplantation the number of rejection episodes was significantly lower in the first 3 months in the PUVA-treated patient group.

Adult↗
PubMed1988

A physiological role for DNA supercoiling in the osmotic regulation of gene expression in S. typhimurium and E. coli.

The proU locus encodes an osmotically inducible glycine betaine transport system that is important in the adaptation to osmotic stress. We present evidence that DNA supercoiling plays a key role in the osmotic induction of proU transcription. An increase in extracellular osmolarity increases in vivo DNA supercoiling, and the expression of proU is highly sensitive to these changes. Furthermore, topA mutations can mimic an increase in osmolarity, facilitating proU expression even in media of low osmolarity in which it is not normally expressed. Selection for trans-acting mutations that affect proU expression has yielded only mutations that alter DNA supercoiling, either in topA or a new genetic locus, osmZ, which strongly influences in vivo supercoiling. Mutations in osmZ are highly pleiotropic, affecting expression of a variety of chromosomal genes including ompF, ompC, fimA, and the bgl operon, as well as increasing the frequency of site-specific DNA inversions that mediate fimbrial phase variation.

Betaine↗
PubMed1988

Patterns of mating and mitochondrial DNA inheritance in the agaric Basidiomycete Coprinus cinereus.

Patterns of mating and mitochondrial DNA (mtDNA) inheritance were investigated for the Basidiomycete, Coprinus cinereus in order to better understand the relationship of reproductive biology and mtDNA evolution in fungi. Results showed that the unique mating system of basidiomycetes can lead to the formation of mitochondrial mosaics (i.e., colonies composed of sectors differing in mtDNA). Mitochondria do not migrate along with nuclei during mating. Intracellular mixed or recombinant mtDNA molecules were not observed. Interestingly, it was found that mating asymmetry, caused by nonreciprocal nuclear migration, may be an important part of the reproductive biology of C. cinereus.

Agaricales↗
PubMed1987

Photochemical donor pretreatment in clinical kidney transplantation--preliminary report.

Extended experimental experience with the efficacy of pretreating the kidney donor and the allograft by means of photochemotherapy (photosensitizer + UVA irradiation = PUVA) was adopted in clinical kidney transplantation. In a preliminary unrandomized study similar patient populations were treated by generally uniform methods. Thirty-three PUVA-pretreated kidneys (group A) were compared with the experience regarding 26 non-pretreated kidney allografts (group B). The number of rejection episodes was significantly lower in the first 3 months in group A (p less than 0.05 vs group B) and fewer grafts failed because of irreversible rejection (2 vs 5). Furthermore, in group A the rate of infectious complications was lower (18% vs 34%). The cumulative allograft survival at 3 months was improved from 65% in group B to 81% in group A and at 12 months from 65% 76%, respectively. These differences were not significant. Therefore, our preliminary clinical experience with a photochemical donor pretreatment is encouraging and further use in a randomized study seems to be necessary.

Adolescent↗
PubMed1987

Individually disparate anti-inflammatory in-vivo susceptibility to corticosteroids in renal transplant recipients.

We used the strength of suppression of the interleukin-1-induced peak CRP response (CRPmax) post-transplant as a measure for the individual steroid susceptibility in vivo. This suppressive effect proved to be fully reversible after abrogation of steroid therapy following graft removal. The standardized suppressive therapy immediately post-transplant led to extremely different results in individual patients ranging from no suppression (26.1% of the patients) to a strong or practically absolute suppression of CRP synthesis in 20.7% of the patients studied. This behaviour is also reflected in anti-rejection bolus therapy whereby the percentage of prednisolone resistant patients strongly correlated with increasing (unsuppressed) CRPmax values. From our data we conclude that the disparate anti-inflammatory susceptibility for corticosteroids seems to be an individual feature of patients under high-dose steroid treatment.

Azathioprine↗
PubMed1986

[Present status and perspectives of kidney transplantation].

The kidney transplantation and the dialysis are established procedures in the treatment of patients with renal insufficiency. The indication for kidney transplantation could be enlarged by new recognitions of immunology and by the introduction of new immunosuppressive medicaments with simultaneous improvement of the results of the transplantations during the last ten years. The urgently necessary increase of the frequency of transplantation by the supply of donor kidneys must be the task of the next years.

Adolescent↗
PubMed1986

Binding protein dependent transport of glycine betaine and its osmotic regulation in Escherichia coli K12.

Glycine betaine, which functions as an osmoprotectant, is accumulated to high intracellular concentrations in Escherichia coli at high osmolarity. We demonstrate the presence of a high-affinity, binding protein dependent transport system for glycine betaine, which is encoded by the proU region. We show the osmotically regulated synthesis of a 32 kDa periplasmic protein that is a glycine betaine binding protein with a KD of 1.4 microM. ProU-mediated glycine betaine transport is osmotically stimulated at the level of gene expression. The osmolarity of the medium also regulates the activity of the transport system, while binding of glycine betaine to its binding protein is independent of the osmolarity. We also find a second glycine betaine transport system that is dependent on proP and exhibits a lower substrate affinity. Like ProU, this system is regulated at two levels: both gene expression and the activity of the transport system are osmotically stimulated. Using lambda plac Mu-generated lacZ operon and gene fusions, we find that expression of the proU region is osmotically regulated at the level of transcription. We cloned a part of the proU region together with the phi(proU-lacZ)hyb2 gene fusion into a multicopy plasmid and show that the DNA sequences required in cis for osmotic regulation are present on the plasmid.

Bacteriophage lambda↗
PubMed1986

Regulation of envelope protein composition during adaptation to osmotic stress in Escherichia coli.

Adaptation to osmotic stress alters the amounts of several specific proteins in the Escherichia coli K-12 envelope. The most striking feature of the response to elevated osmolarity was the strong induction of a periplasmic protein with an Mr of 31,000. This protein was absent in mutants with lambda plac Mu insertions in an osmotically inducible locus mapping near 58 min. The insertions are likely to be in proU, a locus encoding a transport activity for the osmoprotectants glycine betaine and proline. Factors affecting the extent of proU induction were identified by direct examination of periplasmic proteins on sodium dodecyl sulfate gels and by measuring beta-galactosidase activity from proU-lac fusions. Expression was stimulated by increasing additions of salt or sucrose to minimal medium, up to a maximum at 0.5 M NaCl. Exogenous glycine betaine acted as an osmoregulatory signal; its addition to the high-osmolarity medium substantially repressed the expression of the 31,000-dalton periplasmic protein and the proU-lac+ fusions. Elevated osmolarity also caused the appearance of a second periplasmic protein (Mr = 16,000), and severe reduction in the amounts of two others. In the outer membrane, the well-characterized repression of OmpF by high osmolarity was observed and was reversed by glycine betaine. Additional changes in membrane composition were also responsive to glycine betaine regulation.

Adaptation, Physiological↗
PubMed1986

[Serologic studies in patients with early transplant failure].

The appearance, specificity and dynamics of donor reactive antibodies have been studied in 9 patients who experienced early irreversible graft failure. In 5 out of 9 patients we were able to detect donor reactive antibodies. Their reaction patterns may be ascribed to a common responder type ("high responder"). Diagnostic and preventive possibilities for preventing early irreversible graft failures have been discussed.

Antibodies↗
PubMed1986

[In vitro sensitivity of T lymphocytes to theophylline in healthy adults and patients following cadaver kidney allotransplantation].

In the peripheral blood of healthy adults the number of theophylline-resistant T-lymphocytes (T-res) is 51 +/- 4% and 1,161 +/- 326/microliter, respectively, and the number of theophyllins-sensitive 11 +/- 2% and 252 +/- 95/microliters. The membrane markers show a heterogeneous distribution. The quotient from T-res/T-sens is 4.9 +/- 1.3. Within the T-sens 14% are CD4+ and 30% CD8+, 29% carry Fc-IgC and 34% Fc-IgM-receptors. Thus the T-res in their netto-function were helper cells and the T-sens suppressor/cytotox cells. Before the transplantation the preoperative ratio of the two subpopulation is significantly diminished (Q = 3.66 +/- 1.53), however, prognostic statements cannot be deduced from this. Activations of the immune system (rejection crises, cytomegalovirus infections) are accompanied by significant diminutions of the T-sens, whereby the T-res/T-sens-Quotient increases. Thus they are unequivocally included into immunoregulatory processes.

Adolescent↗