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Biomedical subjects

K Lang

Publications and source records attributed to K Lang.

At least 109 records · Page 6Linked to original sources
PubMed1986

Use of a trypsin-pulse method to study the refolding pathway of ribonuclease.

Trypsin pulses, applied after varying times of refolding, have been employed to probe the accessibility of the polypeptide chain of ribonuclease A during the process of refolding. The increase in resistance against proteolytic cleavage was measured by activity assays and by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The sites of cleavage which become inaccessible in the course of refolding are located in the 31 - 39 chain segment of the ribonuclease chain. Protection of this region against attack by trypsin is attained on the major slow refolding pathway in parallel with the formation of a native-like folded, active intermediate, when refolding is carried out under conditions which strongly stabilize the folded state. Under conditions of marginal stability intermediates are not observed during refolding and the formation of trypsin-resistant molecules occurs with the same kinetics as the generation of native ribonuclease. In the native protein the 31 - 39 region of the ribonuclease chain largely forms a loop structure, which is located at the surface of the molecule. Our results indicate that this part of the sequence is still accessible at early stages of refolding, when a hydrogen-bonded network is formed. It is structured and hence does not become inaccessible until the formation of the overall folded native or native-like structure. This suggests that the 31 - 39 region of the ribonuclease chain is not important for early steps which direct the pathway of refolding.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Folding kinetics of mammalian ribonucleases.

The folding kinetics of seven different pancreatic ribonucleases are compared both under native conditions and within the unfolding transition. In general, the folding kinetics of these proteins are similar despite numerous amino acid substitutions. Ribonucleases with 4-6 proline residues show 80% slow-folding species. For three ribonucleases with 7 prolines this number increases to 90%. Porcine ribonuclease with a unique Pro 114-Pro 115 sequence folds significantly slower than other ribonucleases which do not show this sequence.

Amino Acid Sequence↗
PubMed1986

[Diagnosis of thoracic aortic aneurysms and dissections using transesophageal echocardiography].

Transesophageal echocardiography was performed in 25 patients with the clinical suspicion of an aneurysm or dissection of the thoracic aorta. The results obtained were compared to those of conventional transthoracic echocardiography. An aortic dissection was found in 11 patients, an aortic aneurysm in 9 patients, and an aneurysm of the left subclavian artery, an abscess of the aortic ring and a perforated aortic sinus in one patient each. In 2 patients no abnormalities of the thoracic aorta could be found. The intimal flap was detected in 11 patients with transesophageal imaging and in 9 patients with the transthoracic approach. Aortic dissection was suspected in another 5 patients with transthoracic echocardiography which could be excluded by transesophageal echocardiography. In 13 patients (52%) imaging of the descending thoracic aorta was not possible with transthoracic echocardiography but in all patients it was possible from the transesophageal approach. Transesophageal echocardiography seems to be a useful diagnostic approach when diseases of the thoracic aorta were clinically suspected.

Abscess↗
PubMed1986

[Conservative therapy of phimosis].

Worldwide in about ten percent of boys general circumcision is performed. The motivations are religious or other rites and ethnic customs, but no scientific medical indication exist for this intervention, even not the small group with inborn phimosis. For these until now only the surgical way is given by circumcision. In 56 cases of boys before puberty with severe phimosis 53 could be completely cured by combined parenteral HCG and local Corticoid treatment within 4-6 weeks. The longtime follow up study did not show any later side effect. The therapeutic scheme is given.

Administration, Topical↗
PubMed1985

[Heart surgery with extracorporeal circulation in long-term hemodialysis patients].

Prolongation of life expectancy achieved by chronic dialysis permits occurrence of correctable cardiac disease to an increasing degree. In contrast to the previously poor prognosis in dialysis patients with coronary and valvular heart disease the present series demonstrates successful management of such interventions. Nine patients are presented (8 bypass operations, one aortic valve replacement) with a mean age of 51 years and a mean duration of dialysis treatment of 47 months. Patient risks are not markedly increased by this additional disease. Patients with chronic renal insufficiency and chronic continuous dialysis should not generally be excluded from surgery due to an assumed increased risk of operation.

Adult↗
PubMed1985

Clinical significance of different serum tumor markers in gynecological malignancies.

The purpose of this study was to compare the diagnostic significance of serum tumor markers in patients with gynecological malignancies and to evaluate the usefulness of the markers in the follow-up after primary treatment. Determined were tissue polypeptide antigen (TPA), carcinoembryonic antigen (CEA), and phosphohexose isomerase (PHI). Serum samples from 200 patients with cervical cancer, 206 patients with endometrial cancer, and 254 patients with ovarian cancer were analyzed. With regard to specificity, CEA and PHI exhibited false positive rates below 10% in normal controls (N = 96). For TPA, the same result was obtained only by using 120 U/l as a cut-off level. As for sensitivity, positive rates above 50% prior to therapy were demonstrated by PHI and TPA in ovarian cancer as well as CEA in cervical cancer. All three tumor markers showed some decline in positiveness after primary therapy. In ovarian cancer the decline of PHI and TPA strongly correlates with the achievable tumor resection. During the follow-up, all markers demonstrated some discriminatory power by comparing patients with recurrent disease versus recurrence free. Especially PHI and TPA in ovarian cancer, CEA in cervical cancer, and PHI in endometrial cancer seem to be the most suitable markers.

Carcinoembryonic Antigen↗
PubMed1981

Selective cell culture of brain cells by serum-free, hormone-supplemented media: a comparative morphological study.

We cultured single cell suspensions derived from enzymatically digested rat and mouse brains in the serum-free, hormone-supplemented media originally established for culturing glioma (C6) and neuroblastoma cell lines (B104). We succeeded in selecting different cell types by varying the hormones added to the culture medium. In addition to the medium the attachment factors used for coating the culture dishes proved important for the establishment of a selective culture system. In a comparative morphological study we show that different particular microenvironmental conditions determine the growth and/or survival of different cell types of dissociated brain cells.

Animals↗
PubMed1980

Renal handling of urate in healthy man in hyperuricaemia and renal insufficiency: circadian fluctuation, effect of water diuresis and of uricosuric agents.

To differentiate between extrarenal and renal causes of hyperuricaemia and gout, clearances of urate and creatinine were monitored for 3 1/2 days in fifty-two individuals (seven with a history of gout) with no gross impairment of renal function (creatinine clearance 52-137 ml/min). Dietary purine intake was kept constant. Monophasic circadian fluctuations of fractional urate excretion (= urate clearance over creatinine clearance) were observed with peak values in the afternoon, about 50% higher than during the night. Circadian fluctuations of urinary flow rate were almost identical. However, enhancement of urinary flow rate due to water diuresis had no effect on urate clearance. Despite wide variation of plasma urate concentrations among different individuals (+/- 30% SD), daily urate excretion varied little (+/- 4% SD) and did not correlate with plasma urate (r = 0.03). Thus extrarenal factors appear not to account for the occurrence of hyperuricaemia in these patients. In contrast, a clearcut negative correlation was apparent between plasma urate concentration and fractional urate clearance (r = 0.72), which could fully account for the variations of plasma urate concentration. To elucidate further the mechanism responsible for antiuricosuria in hyperuricaemic patients, the effects of the uricosuric agents benzbromarone and probenecid were tested. A clearcut correlation was apparent between control fractional urate excretion and uricosuric effect of both benzbromarone and probenecid (r = 0.83 and 0.88, respectively), suggesting that anti-uricosuria was due to defective secretion. In an additional series, the uricosuric effect of probenecid was tested in ten patients with renal insufficiency. In these patients the uricosuric effect was clearly blunted, indicating that urate reabsorption is reduced in renal insufficiency.

Adult↗
PubMed1979

[Sulfites in infusion solutions].

9 commercially available high-calorie carbohydrate solutions were investigated for their sulfite content. It became evident that 6 manufacturers of infusion solutions add varying amounts of sulfite to their solutions. We consider such an addition to be unnecessary and risky from the toxicological point of view.

Carbohydrates↗
PubMed1978

Diagnosis of dissecting aortic aneurysm with suprasternal echocardiography.

A 33 year old woman with Marfan's syndrome and aortic root dissection was studied with precordial and suprasternal echocardiography. The precordial approach revealed some typical features of aortic root dissection. With suprasternal echocardiography it was possible to visualize the characteristic diagnostic feature of this disease: within the aortic lumen an m-shaped pattern--the aortic intimal flap--moving downward to the posterior aortic wall during systole. The diagnosis was confirmed with aortic cineangiography and intraoperative findings. Thus, suprasternal echocardiography can be a useful method of detecting aortic root dissection, especially in patients with aortic arch dissection alone.

Adult↗