Isometric contraction induces the Ca2+-independent activation of the endothelial nitric oxide synthase.

Shear stress and tyrosine phosphatase inhibitors have been shown to activate the endothelial NO synthase (eNOS) in a Ca2+/calmodulin-independent manner. We report here that isometric contraction of rabbit aorta activates eNOS by a pharmacologically identical pathway. Endothelium-intact aortic rings were precontracted under isometric conditions up to 60% of the maximal phenylephrine-induced tone. The NO synthase inhibitor NGnitro-L-arginine (L-NA) and the soluble guanylyl cyclase inhibitor NS 2028 induced an additional contraction, the amplitude of which depended on the level of precontraction. The maximal production of NO by isometrically contracted aortic rings (as estimated by the increase in cGMP in detector smooth muscle cells in a superfusion bioassay) was observed during the initial phase of isometric contraction and was greater than that detected following the application of acetylcholine. The supplementary L-NA-induced increase in vascular tone was inhibited by the nonselective kinase inhibitor staurosporine and the tyrosine kinase inhibitors erbstatin A and herbimycin A. Another tyrosine kinase inhibitor, genistein, the calmodulin antagonist calmidazolium, and the selective protein kinase C inhibitor, Ro 31-8220, had no effect. Coincident with the enhanced NO formation during isometric contraction was an increase in the tyrosine phosphorylation of endothelial proteins, which also correlated with the level of precontraction. Thus, isometric contraction activates eNOS via a Ca2+-independent, tyrosine kinase inhibitor-sensitive pathway and, like shear stress, seems to be an independent determinant of mechanically induced NO formation.

Ferula asa-foetida and Curcuma longa in traditional medical treatment and diet in Nepal.

Food and eating have powerful symbolic value among the hinduistically-influenced ethnic groups of Nepal. In addition, food plays a major role in the concepts of illness and curing and constitute an integral part of traditional medical prescriptions. Materials that are consumed in 0.5-1.5 g amounts in the daily diet (e.g. the spices turmeric and asafoetida) are used in minute amounts for medical purposes. Why? Three hypotheses are offered here to discuss this issue.

[PUVA treatment of organ transplants--experimental and clinical results]. / PUVA-Behandlung von Organtransplantaten--experimentelle und klinische Ergebnisse.

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.

Reduced MHC class II antigen expression on rat heart and kidney cells after in vitro exposure to longwave ultraviolet irradiation.

The pretreatment of both kidney and heart donor with the photosensitizer 8-methoxy-psoralen followed by in vitro longwave ultraviolet graft irradiation (PUVA therapy) significantly prolonged graft survival times in rats even across a strong major histocompatibility complex (MHC) barrier. Immunohistological studies using monoclonal antibodies (Mab) to rat MHC class I and II antigens showed a significant reduction of class II antigen expression after PUVA therapy in both Sprague-Dawley rat kidneys and hearts. Using MHC class I Mab there were no differences in distribution pattern in untreated as well as in PUVA treated organs. Thus, our results represent the first in vivo evidence that photochemotherapy-induced graft survival time prolongation is closely connected with its ability to reduce MHC class II antigen expression.

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.

31P-NMR spectroscopy and ultrastructural studies on nephrotoxicity of cyclosporine A.

NMR-spectroscopy and electron microscopy were applied in order to find out whether nephrotoxic effects of cyclosporine A in combination with ischaemia on rat kidney are of significance for the energy metabolism of the organ. CSA was administered in daily doses of 15 mg/kg rat over 20 days. Use was made of the particular advantage of 31P-NMR-spectroscopy to follow up the dynamics of high-energy phosphate concentrations in the same tissue. Ultrastructural changes were observed in the region of the proximal tubule. Some mitochondria showed degenerative changes, others increased density of cristae. The total number of mitochondria was increased. This observation together with the coexistence of vacuolarly degenerated mitochondria and mitochondria with increased activity after CSA treatment is interpreted as expression of a compensatory mechanism that keeps constant the totality of high-energy phosphates despite damage to some mitochondria.

Synergistic effect of photochemical donor pretreatment and cyclosporin therapy of the recipient on rat renal allograft survival.

Dose-response studies of cyclosporin (CsA) established that doses of 2 mg/kg body weight on 4 consecutive days (0-3) or higher gave complete suppression of rejection and permanent survival of all rat kidney allografts, while a dose of 2 mg/kg body weight on day 0 was much less effective in preventing deleterious rejection (30% permanent survival). Photochemical pretreatment of the kidney donor with 8-methoxypsoralen (8-MOP) and direct long-wave ultraviolet irradiation (UVA) of the kidney (PUVA) therapy) significantly prolonged the subsequent graft survival in allogeneic recipients. Forty per cent of the animals survived more than 100 days. However, when PUVA-treated kidney allografts were transplanted into temporary CsA immunosuppressed recipients (2 mg/kg on day 0) the graft survival rate was further improved. Seventy per cent of the PUVA + CsA-treated recipients survived permanently. Therefore, a synergistic effect of PUVA pretreatment and low-dose CsA therapy on rat renal allograft survival was demonstrated. The results suggested a possible clinical application of this treatment regimen in order to avoid high nephrotoxic CsA doses.

Synergistic effect of donor pretreatment with 8-methoxypsoralen and ultraviolet irradiation of the graft plus azathioprine and prednisolone therapy in prolonging rat renal allograft survival.

Pretreatment of the kidney donor with 8-methoxy-psoralen (8-MOP) and direct longwave ultraviolet (UVA) irradiation of the kidney graft (PUVA therapy) significantly prolonged survival in allogeneic recipients. 40% of the recipients survived more than 100 days with normal transplant function. The addition of standard clinical immunosuppressive agents azathioprine and prednisolone (both at dosages of 15 mg/kg body weight/day for 21 days) to the PUVA therapy further improved graft survival rate, with a recipient survival rate of 62.5%. The two drugs alone were less effective in prolonging graft survival rate (28.5%). A synergistic effect of PUVA therapy and standard immunosuppressive treatment with azathioprine and prednisolone was demonstrated. This suggested a possible clinical application of this type of immunosuppression and immunoregulation.

Prolongation of rat renal allograft survival time by donor pretreatment with 8-methoxypsoralen and longwave ultraviolet irradiation of the graft (PUVA therapy).

Pretreatment of the kidney donor with 8-methoxypsoralen (8-MOP) and ex vivo longwave ultraviolet irradiation (UVA) of the kidney prolonged the subsequent survival on allogeneic recipients. The efficacy of this treatment seems to be dependent on the time and dose of UVA irradiation rather than on the dose of 8-MOP. In conclusion, PUVA treatment is effective in reducing the immunogenicity of the rat kidney allograft, although the mechanism remains unclear. These experimental findings are new and preliminary results in clinical human kidney transplantation are favourable.

Postprandial hyperoxaluria and intestinal oxalate absorption in idiopathic renal stone disease.

Calcium and oxalate were studied in daily, fasting and postprandial urine specimens from healthy subjects and patients with idiopathic renal calcium stones in response to a test meal free of oxalate, and supplemented with calcium and 14carbon-oxalic acid. The data showed that the amount of oxalate in fasting urine of patients with stones did not differ from that in controls. Generally, patients with stones had considerable postprandial hyperoxaluria in terms of excretion and concentration, associated with a significantly higher degree of supersaturation with regard to calcium oxalate compared to controls. These findings were paralleled by decreased intestinal absorption of 14carbon-oxalate and by unchanged 24-hour urinary oxalate. Although the source of increased postprandial oxalate in patients with stones is not clear the possibility of enhanced de novo synthesis from oxalate precursors is discussed. In patients with different types of calciuria the 2 main risk factors (hyperoxaluria and hypercalciuria) for the process of stone formation are recognizable more readily in the postprandial urine specimens than in fasting or daily urine specimens.

Prevention of osteonecrosis following renal transplantation by using vitamin D2 (ergocalciferol).

Osteonecrosis is a frequently disabling complication of renal transplantation. Thirty-one of 244 patients (12.7%), who received cadaver renal transplants from 1968 to 1978 developed an osteonecrosis. An analysis of 14 possible risk factors suggested that only the following were significantly more frequent in the osteonecrosis group: greater than 3 pulse doses of 1.2 g prednisolone, serum creatinine greater than 133 mumol/L, steroid-induced diabetes mellitus and second and subsequent transplantation. An important decline in the incidence of osteonecrosis (26.7 per cent to 6.5 per cent) was seen with prophylactic vitamin D2 treatment and the onset of osteonecrosis was on average one year later. Dangerous side effects of the large doses of vitamin D2 were minimal. Hypercalcaemia due to overdosage with vitamin D2 during simultaneous prednisolone therapy was usually mild and returned to normal in a few days by dose reduction.

[Use of gen5 and gen6 ts-mutants of phage T3 as indicators of inhibitors of DNA synthesis]. / Nutzung von Gen5 und Gen6 ts-Mutanten des Phagen T3 für die Anzeige von Hemmstoffen der DNS-Synthese.

In an enzyme-specific drug screening system nalidixic acid and 3'-FTdR, inhibitors of DNA synthesis, both reduce the growth of wild type and temperature-sensitive point mutants of phage T3 with different efficiencies. The wild type shows the strongest sensitivity against the drugs, while an exonuclease mutant is the most insensitive variant. The DNA polymerase mutants exhibit an intermediate degree of inhibition. The anthracycline antibiotics violamycin BI and adriblastin which preferentially inhibit RNA synthesis show the same degree of inhibition for all mutants. This is true also for the RNA synthesis inhibitor lambdamycin, which is identical with chartreusin. The protein synthesis inhibitors chloramphenicol and o-phenanthroline, a chelating agent, impair all mutants to the same extent. Our data confirm the hypothesis that structural variants of essential viral enzymes, when compared with the wild type should reveal different sensitivities against specific inhibitors and show that this T3 system could be used for the indication of specific inhibitors of DNA synthesis.

The social consequences of accidental injury.

A case history is presented showing how traditional beliefs affect the understanding of accidental injury. The impact of such an event on the life of a particular village is also described, and certain implications for medical workers are noted.