Biomedical subjects
Publications and source records attributed to H A Hansen.
The structure of the modified dipeptide Z-Glyt-Gly-OBzl is reported with special emphasis on the linear and angular dimensions of the thiopeptide unit. It is shown that, except for the differences between the carbonyl and the thioacyl bond lengths, there are no significant differences between the oxopeptide and the thiopeptide unit.
This report describes our experience with six patients with dysphagia as the sole manifestation of radiographic, inconspicuous primary lung cancer and well-defined esophageal lesion by barium swallow. Esophagograms suggested leiomyoma, benign esophageal stricture, duplication cyst, achalasia, and primary carcinoma of the esophagus. Careful evaluation of the chest radiographs in all patients presenting with dysphagia is emphasized. The majority of esophageal findings are subcarinal and bronchoscopy should be considered essential in the workup of these patients.
This report details our experience in 40 patients with benign strictures of the esophagus who underwent colon (or gastric) interposition with our without esophageal resection between 1972 and 1980. There were 23 men and 17 women ranging from 5 to 76 years old. Twenty-seven patients had fibrotic strictures secondary to reflux esophagitis including 12 after failure of antireflux procedures; 4 had caustic strictures; 3 had a Barrett's esophagus; 2 had systemic candidiasis; 2 had scleroderma; and in 2 the etiology was undetermined. the right colon was used in 27 patients, the left colon in 4, the transverse colon in 1, and the jejunum in 1. In 7 patients the stomach was employed because of vascular insufficiency of the colon. Three surgical approaches were utilized. Manometric studies were done post-operatively in 10 patients. Complications occurred in 7 patients: cervical leaks, 4; reflux colitis, 2; and a late cervical stricture, 1. There were 4 deaths, only 1 of which was related directly to technique. This report summarizes the beneficial effect of right colon interposition for long esophageal strictures. Its vasculature is adequate, and it functions properly to propel food into the stomach irrespective of the peristaltic orientation.
In a retrospective study the frequency of infertility was estimated in women operated for perforated or non-perforated appendicitis before the age of 25. Of the 48 patients with simple perforation 19% were infertile, while this frequency was 31% in 16 patients with Douglas abscess. In the control group of 58 patients 12% could not have children. It is concluded that it is unlikely that appendicitis with perforation will cause infertility unless there is a Douglas abscess.
Although well protected and infrequently injured, penetration of the esophagus has a reported mortality of 10 to 30 per cent. The results of the management of seventy-seven patients with noniatrogenic penetrating injuries of the esophagus were reviewed. The region of esophageal injury was cervical in forty-five patients, intrathoracic in twenty-one patients, and intraabdominal in eleven patients. Gunshot wounds accounted for 75 per cent of the injuries. The overall mortality was 23 per cent. The highest morbidity and mortality was among patients with intrathoracic injuries, due to both difficulty in exposure and complexity of associated injuries. Because of the high incidence of late complications in intrathoracic injuries, cervical diversion and tube gastrostomy or complete esophageal exclusion must be considered early. Fundoplastic procedures were used in four patients with distal esophageal injuries. Although the overall mortality from truncal penetrating wounds has improved in recent years, the mortality from esophageal injuries remains high, reflecting a need for advancement in initial operative management.
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A recombinant DNA Chinese hamster ovary (CHO) cell line which produces tissue-type plasminogen activator (t-PA) was cultivated continuously in suspension with a constant dilution rate of 0.5 day-1. The cultivation consisted of four phases with four different ammonium chloride concentrations (0, 2.5, 5, and 7.5 mM) in the feed medium, causing a reactor ammonium concentration of up to 8 mM. Cell growth was not inhibited by these high ammonium concentrations, as cell densities of around 2.3 x 10(6) cells mL-1 were established. In contrast, the production of t-PA was reduced under high ammonium concentration. The decrease in specific t-PA production could be due to either a negative ammonium influence on productivity or a limitation of medium components, e.g., amino acids. Cell metabolism was changed under high ammonium concentrations, seen most clearly by a decrease in specific ammonium production by a factor of 8 and an increase in specific alanine production of 30%.
Preliminary electron density maps of the large and the small ribosomal particles from halophilic and thermophilic sources, phased by the isomorphous replacement method, have been constructed at intermediate resolution. These maps contain features comparable in size with what is expected for the corresponding particles, and their packing arrangements are in accord with the schemes obtained by ab-initio procedures as well as with the motifs observed in thin sections of the crystals by electron microscopy. To phase higher resolution data, procedures are being developed for derivatization by specific labeling of the ribosomal particles at selected locations with rather small and dense clusters. Potential binding sites are being inserted either by site directed mutagenesis or by chemical modifications to facilitate cluster binding on the surface of the halophilic large and the thermophilic small ribosomal particles, which yield the crystals diffracting to highest resolution (2.9 and 7.3 A (1 A = 0.1 nm), respectively). For this purpose, the surface of these ribosomal particles is being characterized and procedures are being developed for quantitative detachment of selected ribosomal proteins and for their incorporation into core particles. The genes of these proteins are being cloned, sequenced, mutated to introduce reactive side groups, mainly cysteines, and overexpressed. In parallel, two in situ small and stable complexes were isolated from the halophilic ribosome. Procedures for their crystal production in large quantities are currently being developed. Models, reconstructed at low resolution from crystalline arrays of ribosomes and their large subunits, are being used for initial low-resolution phasing of the X-ray amplitudes. The interpretation of these models stimulated the design and the crystallization of complexes mimicking defined functional states of a higher quality than those obtained for isolated ribosomes. These models also inspired modelling experiments according to results of functional studies, performed elsewhere, focusing on the progression of nascent proteins.