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Biomedical subjects

A L Weber

Publications and source records attributed to A L Weber.

At least 109 records · Page 6Linked to original sources
PubMed1979

Evaluation of mucoceles of the paranasal sinuses with computed tomography.

Eighteen patients with mucoceles of the paranasal sinuses were studied by plain radiography, pluridirectional tomography, and computed tomography (CT). Sixteen of the lesions had a homogeneous appearance on CT but demonstrated variable absorption characteristics, with acutely infected mucoceles showing rim enhancement. Plain radiography and pluridirectional tomography were usually sufficient for making a diagnosis and defining the extent of the lesion, but CT more accurately demonstrated orbital and intracranial extension. Both transverse and coronal CT are essential for adequate evaluation.

Adolescent↗
PubMed1978

The formation of peptides from the 2'(3')-glycyl ester of a nucleotide.

We have synthesized 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate), an analogue of the 3'-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5'-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine. The aminolysis of 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.

Adenosine Monophosphate↗
PubMed1978

Genetic code correlations: amino acids and their anticodon nucleotides.

The data here show direct correlations between both the hydrophobicity and the hydrophilicity of the homocodonic amino acids and their anticodon nucleotides. While the differences between properties of uracil and cytosine derivatives are small, further data show that uracil has an affinity for charged species. Although these data suggest that molecular relationships between amino acids and anticodons were responsible for the origin of the code, it is not clear what the mechanism of the origin might have been.

Amino Acids↗
PubMed1978

Amino acid activation with adenosine 5'-phosphorimidazolide.

Amino acids are activated by reaction with adenosine 5'-phosphorimidazolide in aqueous imidazole buffers. If adenosine 5'-(O-methylphosphate), an analogue of the 3'-terminus of t-RNA is present, 2'(3')-O-aminoacyladenosine 5'-(O-methylphosphate) is formed. Fifteen percent of this compound accumulated at pH 5.8, but less was formed at higher pHs. The highest efficiency of utilization if ImpA attained in our experiments was about 24%. Analogous reactions occured with several other amino acids, including a number that have functional side-chains.

Adenosine Monophosphate↗
PubMed1978

Computed tomography of the paranasal sinuses and face: part I. Normal anatomy.

With the ability to image both bone and soft tissue structures, computed tomography (CT) is capable of visualizing many normal anatomical structures of the paranasal sinuses and face not seen with other radiological techniques. The superficial and deep fat planes, all of the muscles of mastication, and many of the facial muscles are readily identified. The extraocular muscles, optic nerves, and globes are clearly seen. The purpose of this report is to review the normal anatomy of the paranasal sinuses and face imaged by CT in both the transverse and coronal planes.

Face↗
PubMed1978

Computed tomography of the paranasal sinuses and face: part II. Pathological anatomy.

Computed tomography (CT) has added an important new dimension to the radiological evaluation of diseases of the paranasal sinuses and face. Using transverse and coronal scans, accurate assessment of the character and extent of mass lesions in this region can be achieved. Erosion of thin bony lamine and involvement of soft tissue structures of the face can be seen. Most important, CT is capable of precisely defining the extension of lesions into the pterygopalatine fossa, orbit, and cranial cavity, information that is essential for therapeutic planning.

Adult↗
PubMed1978

Reversible respiratory disease in beryllium workers.

A medical and environmental survey was carried out in a beryllium extraction and processing plant in 1971, and a follow-up study was done in 1974. Peak air concentrations of beryllium of as much as 50 times the accepted peak limit value were found in the plant in 1971. Radiographic changes of interstitial disease were found in 31 workers, hypoxemia was found in 20, and in 11 workers a combination of hypoxemia and radiographic changes of interstitial disease was seen. Follow-up in 1974 showed that air concentrations had all decreased significantly, mainly because of improvements in engineering and ventilation in the plant. Improvement in hypoxemia and decreased alveolar-arterial O2 tension difference at rest ([A-a]DO2) were noted in 13 of the 20 men who had hypoxemia in 1971 and were available for follow-up. In addition, radiographic abnormalities of interstitial disease were reversed in some workers. Our results suggest that improvement in gas exchange and radiographic findings of interstitial disease occurs when peak air concentrations of beryllium are decreased. Our approach in combining environmental and medical screening in workers exposed to beryllium enabled us to identify persons with early changes, to detect reversible abnormalities, and to correlate air concentrations with the medical status of workers.

Adult↗
PubMed1978

Sialography of salivary gland tumors with fluoroscopy and tomography.

Sialography with fluoroscopy and tomography has increased the accuracy of detecting and delineating mass lesions of the parotid gland. Lesions which are small, at the periphery of the gland, or in the deep lobe are often most clearly visualized on tomographic sections. Often differentiation of benign from malignant tumors is not possible.

Adenolymphoma↗
PubMed1977

Simultaneous peptide and oligonucleotide formation in mixtures of amino acid, nucleoside triphosphate, imidazole, and magnesium ion.

Simultaneous peptide and oligonucleotide formation was observed in reaction mixtures of amino acid, nucleoside triphosphate, imidazole, and MgCl2. At 70 degrees C in solutions that were evaporated to dryness the formation of peptide for phe and pro was greatest with CTP relative to ATP, GTP, and UTP. Lysine exhibited a preference for GTP and glycine for UTP. At ambient temperature insolution at pH 7.8, CTP was preferred by glycine, but at pH 8.7 UTP was preferred. The glycine nucleotide phosphoramidates were also detected and characterized in reactions at 40 degrees C. The glycine-reaction preference for CTP at pH 7.8 and UTP at 8.7 suggested that the basicity of the nucleoside triphosphate was involved in increasing the peptide yield. CTP near neutrality is the most basic nucleoside triphosphate and the basic anionic form UTP could facilitate peptide formation at pH 8.7. These data, together with information on the complexing of poly(C) by GTP, led to the experimentally approchable hypothesis that GTP, by forming a basic triplex between the cytosine residues adjacent to the peptidyl adenosine and aminoacyl adenosine at the termini of two proto-tRNAs, would promote peptide bond synthesis between the aminoacyl residue and peptidyl residue.

Amino Acids↗