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Biomedical subjects

J Walter

Publications and source records attributed to J Walter.

At least 235 records · Page 13Linked to original sources
PubMed1985

[New scientific and practical education for successful reading training under difficult circumstances].

Neither traditional dyslexia research nor intensive efforts undertaken by the special education sector in reading-writing education have hitherto been able to remedy the fact that relatively large numbers of special education students are unable to read and write when they leave school. Learning to read and write continues to mean drudgery for many children. Experimental research in reading and writing learning processes has achieved approaches capable of providing effective help specifically to the "hard-core" cases of reading and writing failure. This, however, presupposes an understanding of the information processing and storage processes required in reading function, or, rather, of the deficiencies involved. The present contribution therefore intends to familiarize the special education practitioner with the still widely unknown psychological foundations of cognition and memory that are indispensable for implementing effective reading education course.

Child↗
PubMed1984

Structure of bovine pancreatic trypsin inhibitor. Results of joint neutron and X-ray refinement of crystal form II.

The structure of form II crystals of bovine pancreatic trypsin inhibitor has been investigated by joint refinement of X-ray and neutron data. Crystallographic R factors for the final model were 0.200 for the X-ray data extending to 1 A resolution and 0.197 for the 1.8 A neutron data. This model was strongly restrained, with 0.020 A root-mean-square (r.m.s.) departure of bond lengths from their ideal values and 0.019 A r.m.s. departure of planar groups from planarity. The resulting structure was very similar to that of crystal form I (r.m.s. deviation for main chain atoms was 0.40 A); nevertheless larger deviations were observed in particular regions of the chain. Twenty out of 63 ordered water molecules occupy similar positions (deviation less than 1 A) in both models. Eleven amide hydrogens were found to be protected from exchange after three months of soaking the crystals in deuterated mother liquor at pH 8.2. Their locations were in excellent agreement with the results obtained by two-dimensional nuclear magnetic resonance, but the rates of exchange are much lower in the crystalline state.

Amino Acid Sequence↗
PubMed1984

Peptidoglycans as promoters of slow-wave sleep. II. Somnogenic and pyrogenic activities of some naturally occurring muramyl peptides; correlations with mass spectrometric structure determination.

The structures of components of the sleep-promoting material purified from human urine were established by fast atom bombardment-mass spectrometry, as reported in the accompanying paper (Martin, S. A., Karnovsky, M. L., Krueger, J. M., Pappenheimer, J. R., and Biemann, K. (1984) J. Biol. Chem. 259, 12652-12658). We report here that two substances isolated from that preparation, viz. N-acetylglucosaminyl-1,6 -anhydro-N-acetylmuramyl-Ala-gamma-Glu-diaminopimelyl-Ala) and that compound lacking the terminal alanine, are active as somnogens. Cerebro-intraventricular administration of 1 pmol of the glycotetrapeptide was sufficient to induce prolonged excess sleep in rabbits. A similar substance obtained from Brevibacterium divaricatum in which the free carboxyls of the glutamic and diaminopimelic moieties, indicated above, were amidated (N-acetylglucosaminyl-1,6-anhydro-N-anhydromura-myl-Ala-iso- Gln- epsilon-amido-diaminopimelyl -Ala-Ala) was not active as a promoter of slow-wave sleep. Deamidation of this peptide to a mixture of the free dicarboxylic forms produced a somnogenic substance. Our findings show that in addition to the muramyl form of peptidoglycan monomers, the anhydro muramyl form, with no reducing end, is compatible with somnogenic activity. Furthermore, the data obtained with a natural product amplify our earlier observations with smaller synthetic molecules of the importance of amidation/deamidation in the structure-activity relationships of muramyl peptides.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

The refined 2.2-A (0.22-nm) X-ray crystal structure of the ternary complex formed by bovine trypsinogen, valine-valine and the Arg15 analogue of bovine pancreatic trypsin inhibitor.

Large orthorhombic crystals of the complex formed by bovine trypsinogen and a semisynthetic homologous bovine pancreatic trypsin inhibitor with the reactive-site lysine residue replaced by an arginine residue [( Arg15]PTI) have been obtained which are isomorphous with the crystals of PTI-trypsinogen [Bode, W., Schwager, P. and Huber, R. (1978) J. Mol. Biol. 118, 99-112]. The X-ray crystal structure of the ternary complex of trypsinogen-[Arg15]PTI with the dipeptide Val-Val has been determined by X-ray data to 2.2-A (0.22-nm) resolution by means of difference Fourier methods and has been crystallographically refined to a final R-value of 0.17. Replacement of the reactive-site Lys15 by an arginine residue is accompanied in the complex by small movements of polar side groups of trypsin and enclosed solvent molecules within the specificity pocket. Only solvent molecule 414 OH which mediates the hydrogen bond interactions between Lys15 NZ and Asp189 carboxylate is expelled, thus allowing the bulkier guanidyl group to approach this carboxylate. The dipeptide Val-Val binds in the pocket accepting the Ile-Val N-terminus in trypsin. The cavity left by the CD-methyl group of Ile16 upon replacement by a valine residue is only partially filled by slight rearrangements of neighbouring peptide side chains. Part of the positive free energy change observed upon replacement of Ile-Val may allow for the maintenance of this cavity.

Animals↗
PubMed1984

Muramyl peptides. Variation of somnogenic activity with structure.

Sleep-promoting activities of muramyl dipeptide (MDP) (NAc-Mur-L-ala-D-isogln) and the naturally occurring muramyl peptide(s), factor S, have recently been demonstrated. We now have amplified our understanding of structural requirements for somnogenic activity. The effects of several analogs of MDP on rabbit slow-wave sleep are presented and these results are compared to the dose-response relationship for MDP. Some tentative conclusions as to structural requirements for somnogenic activity are presented; most notably, amidation of the free gamma-carboxyl of MDP and several of its analogs resulted in the loss of somnogenic activity. MDP also can induce febrile and immunostimulatory responses. In the present paper, we show that some analogs possess immunostimulatory and pyrogenic activity but not somnogenic activity, thus suggesting that these biological activities of muramyl peptides may, in part, be mediated by separate mechanisms.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Clinical presentation of patients with acute cervical spine injury.

A retrospective review of 67 patients with acute cervical spine fracture and/or dislocation was conducted at two suburban community hospital emergency departments. The mean age was 39, and two-thirds of the patients were male. Motor vehicle accidents and falls accounted for more than 80% of all injuries. On emergency department evaluation, it was found that there was no history of loss of consciousness in 42 patients (63%), no associated cranio-facial injuries in 31 patients (46%), and a normal sensorimotor examination in 59 patients (88%). Thirty-four patients (50%) were evaluated for cervical range of motion, which was found to be normal in one-third of the cases. The absence of mental status changes, cranio-facial injuries, range of motion abnormalities, and focal neurological findings is, therefore, not uncommon in patients who have sustained cervical spine injury.

Acute Disease↗
PubMed1984

Sleep-promoting effects of endogenous pyrogen (interleukin-1).

When infused into the lateral cerebral ventricles of rabbits, human endogenous pyrogen (EP) preparations induced dose-dependent increases in slow-wave sleep concomitant with increasing body temperature. Heating EP to 70 degrees C destroyed its sleep-promoting and pyrogenic activity. Anisomycin (an antipyretic) prevented EP from increasing body temperature without affecting its sleep-promoting activity. Intravenous injection of EP induced fever and transient increases in slow-wave sleep but failed to induce prolonged increases in slow-wave sleep. We conclude that the somnogenic activity of EP is not secondary to its pyrogenic activity.

Animals↗
PubMed1984

[Comparative study of the effect of the calcium antagonist nifedipine, the beta receptor blockers acebutolol and propranolol and their combination on electrophysiologic parameters in the human].

It is well known that in the isolated atrium, nifedipine, verapamil and diltiazem slow down the spontaneous frequency and conduction velocity in the sinus- and in the atrioventricular node. Using therapeutic doses in man, we studied the influence of the calcium-antagonist nifedipine, the beta-blockers acebutolol and propranolol and a combination of these on sinus-node parameters (spontaneous cycle length AA, sinus-node recovery time SNRT, corrected sinus-node recovery time CSNRT, sinoatrial conduction time SACT), and on the intracardiac conduction time (PA-, AH-, HV-interval). Both beta-blockers slowed the spontaneous frequency of depolarization of the sinus-node, but lengthened sinus-node recovery time and sinoatrial conduction time (acebutolol: AA + 6% n.s.; SNRT +5% n.s.; CSNRT +2% n.s.; SACT +33% s.; propranolol: AA +9% n.s.; SNRT +15% s.; CSNRT +37% n.s.; SACT +32% n.s.). Simultaneously PA-, AH and HV-interval lengthened (acebutolol: PA +16% n.s.; AH +7% s.; HV +15% s.; propranolol: PA +19% n.s.; AH +16% s.; HV +9% s.). Nifedipine caused essentially no change in sinus-node parameters nor in intracardiac conduction time in man (AA -11% s.; SNRT -12% s.; CSNRT -7% n.s.; SACT +35% n.s.; PA +4% n.s., AH -2% n.s.; HV +5% n.s.). This is in contrast to results obtained in the isolated atrium, and is different from other calcium-antagonists such as verapamil, gallopamil and diltiazem. The effect of acebutololinduced beta-blockade is not intensified by nifedipine (AA -3% n.s.; SNRT -6% s.; CSNRT -12% s.; SACT -19% n.s.; PA -5% n.s.; AH +3% n.s.; HV +9% n.s.).

Acebutolol↗
PubMed1983

Pancreatic trypsin inhibitor. A new crystal form and its analysis.

Basic pancreatic trypsin inhibitor (Trasylol) was crystallized in a new crystal form with space group P212121 and lattice constants a = 74.1 A, b = 23.4 A, c = 28.9 A. Its structure was determined at 0.94 A resolution applying Patterson search techniques.

Crystallization↗
PubMed1983

Treatment of sleep disturbance in arthritis with chlormezanone.

A double-blind, crossover study was carried out in 31 patients with rheumatoid arthritis or osteoarthritis who suffered from insomnia which was considered to be caused primarily by their disease. Patients received 7-day courses of 400 mg chlormezanone, 200 mg chlormezanone and placebo in a pre-determined random order. Patients rated chlormezanone significantly (p less than 0.025) more effective than placebo in overcoming sleep disturbance and preferred the 400 mg dose. There was also a trend towards better quality of sleep with chlormezanone, although this did not attain statistical significance in this relatively small study. Daytime alertness was similar for both active and placebo treatment periods. Chlormezanone, therefore, would seem to be a useful addition to antirheumatic therapy when there is related insomnia.

Arthritis, Rheumatoid↗
PubMed1983

The X-ray crystal structure analysis of the refined complex formed by bovine trypsin and p-amidinophenylpyruvate at 1.4 A resolution.

The X-ray crystal structure of the complex formed by bovine beta-trypsin and the potent small inhibitor p-amidinophenylpyruvate at pH 7.6, has been determined by difference Fourier methods at 1.4 A resolution and subsequently refined to a crystallographic R value of 0.191, applying diagonal matrix least-squares procedures including energy constraints. The amidino and the phenyl group of this inhibitor are bound to the specificity pocket, essentially as previously observed in benzamidine-trypsin. The reactive Ser195 O gamma of trypsin forms a covalent bond of length 1.7 A to the carbonyl carbon of the pyruvate group. The hybridization of this carbonyl carbon is just between trigonal and tetrahedral. The imidazole ring of His57 is in a correct orientation to form bonds via its N epsilon 2 hydrogen to one of the carboxylate oxygens of p-amidinophenylpyruvate and to Ser195 O gamma. The probable proton shift makes Ser195 O gamma more nucleophilic and the attacked carbonyl carbon of p-amidinophenylpyruvate more electrophilic and thus facilitates bond formation. These specific interactions offer a qualitative explanation for the unique binding properties of p-amidinophenylpyruvate and for the applicability of the quantitative structure-activity relations previously found by Markwardt and coworkers for three series of p-amidinophenylalkanone compounds with carbonyl groups in alpha-, beta- and gamma-position to the phenyl ring.

Animals↗
PubMed1982

Care of the patient receiving antineoplastic drugs.

Caring for patients who receive chemotherapeutic agents is among the most challenging and potentially rewarding dimensions of oncologic nursing practice. The nurse must possess sound knowledge of not only the biologic and behavioral sciences, but also of current oncologic nursing practices, pathology, and the pharmaceutics of antineoplastic drugs. However, comprehensive nursing care must counterbalance clinical expertise with sensitivity to the unique problems patients with cancer and their families experience. Because the nurse is often the only health care professional with whom the patient and family have consistent contact, clinical expertise and sensitivity are of critical importance to the well-being of patients and their families during therapy. Through accurate, ongoing assessment and identification of problems, prompt recognition of learning needs, and intelligent, supportive, and creative interventions, nurses can do much to assure that patients and families receive the comprehensive care to which they are entitled. It is the purpose of this paper to discuss essential aspects of antineoplastic drug therapy and the important role of the nurse in caring for patients receiving this type of treatment.

Antineoplastic Agents↗
PubMed1982

[Prinzmetal phenomenon and a rare coronary anomaly as infarct and death cause of a 45-year-old patient].

We report about the sudden death of a 45-year-old woman with anomalous origin of both coronary arteries from a single ostium in the right sinus of Valsalva, the left coronary artery running between the aorta and the pulmonary trunk. The clinical picture was that of Prinzmetal's form of variant angina, and it preceded death of inferior myocardial infarction. Coronary spasm and the anatomical anomaly were demonstrated by coronary angiography. There was no atheromatous plaque or other obstructive lesion in the dominant right coronary artery which could have explained the inferior myocardial infarction seen at autopsy. This is the first detailed report in which this rare coronary anomaly has been associated with Prinzmetal's variant angina. The demonstration of spasm in the dominant coronary artery and of an infarct in that part of the myocardium supplied by it in the absence of any anatomical obstruction suggests that this patient's death resulted from coronary spasm.

Angina Pectoris, Variant↗