PubMed Health⌕ Search

Biomedical subjects

A L Weber

Publications and source records attributed to A L Weber.

At least 73 records · Page 4Linked to original sources
PubMed1988

Tumors of the paranasal sinuses.

Benign and malignant tumors, including polyps, represent conditions that occur frequently enough to be considered in the differential diagnosis of sinus disease. The locations and extent of these lesions (especially malignant tumors) should be evaluated by CT and MRI. This is especially indicated when malignant lesions extend outside the confines of the paranasal sinuses into adjacent areas, such as the orbit, intracranial cavity, and parapharnygeal space.

Carcinoma, Squamous Cell↗
PubMed1987

The triose model: glyceraldehyde as a source of energy and monomers for prebiotic condensation reactions.

Glyceraldehyde acts as a source of energy and monomers in a new model of the origin of life. The simplest form of the model functions by converting formaldehyde from the environment into glyceraldehyde which spontaneously forms hemiacetal adducts that are oxidized to polyglyceric acid. Polyglyceric acid, in turn, acts as an autocatalyst with a rudimentary replicating ability. A unique property of the model is its ability to unite the origin of metabolism and the origin of polymer synthesis into a single process. Furthermore, the chemical resemblance of the model to glycolysis gives it the potential to develop a biological metabolism in a straightforward manner.

Calorimetry↗
PubMed1987

Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester.

The autocondensation of the glyceroyl thioester S-glyceroyl-ethanethiol yielded oligoglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid to imidazole buffers than in 2,6-lutidine buffers of the same pH. The efficiency of ester bond synthesis was about 20% for 40 mM S-glyceroyl-ethanethiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the oligoglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

Energy Metabolism↗
PubMed1987

Stereoselective formation of a 2'(3')-aminoacyl ester of a nucleotide.

Reaction of DL-serine and adenosine-5-phosphorimidazolide in the presence of adenosine-5'-(O-methylphosphate) and imidazole resulted in the stereoselective synthesis of the aminoacyl nucleotide ester 2'(3')-O-seryl-adenosine-5'-(O-methylphosphate). The enantiomeric excess of D-serine incorporated into 2'(3')-O-seryl-adenosine-5'-(O-methylphosphate) was about 9%. Adenylyl-(5'----N)-serine and an unknown product also incorporated an excess of D-serine; however, serylserine showed an excess of L-serine. The relationship of these results to the origin of the biological pairing of L-amino acids and nucleotides containing D-ribose is discussed.

Adenosine Monophosphate↗
PubMed1987

Ophthalmic manifestations of maxillary sinus mucoceles.

Mucoceles involving any of the paranasal sinuses may present with ophthalmic disturbances. Maxillary antral mucoceles can encroach on the inferior orbit with ocular displacement and compression, proptosis or enophthalmos, lower lid distortion, tethering of extraocular muscles, and ptosis. Periocular pain, erosion of the inferior orbital rim, infraorbital nerve compression, epiphora, and inner canthal swellings are other important presentations. Postoperative mucoceles may involve only a portion of the antrum. Five illustrative cases are presented.

Adult↗
PubMed1987

Abnormally large frontal sinus. II. Nomenclature, pathology, and symptoms.

Based on a review of the literature and analysis of six new cases, three categories of enlarged, aerated sinuses are defined, namely: hypersinus, pneumosinus dilatans, and pneumocele. The information gained by our study of the area variation of the frontal sinuses in a normal population (part I of this paper) was utilized to define the term hypersinus. In this condition there is generalized enlargement of the sinus beyond the upper limit of normal in an asymptomatic patient. The principal difference between pneumosinus dilatans and a pneumocele is the presence of bony thinning or erosion in the latter entity. The clinical findings and the possible etiologies of these conditions are discussed.

Adult↗
PubMed1987

Inflammatory disorders of the paraorbital sinuses and their complications.

This article discusses paranasal sinus infection and mucoceles that affect the orbital cavity. The radiologic findings demonstrated by plain films and computerized tomography (CT) are described. Special emphasis is placed on CT, as it represents the primary modality in assessing orbital complications.

Amyloidosis↗
PubMed1986

Computed tomography of lymphoproliferative disease of the orbit. Report of 50 patients.

Orbital lymphoproliferative disease is one of the most common causes of exophthalmos and palpable masses in the anterior part of the orbit. Axial and coronal computed tomography (CT) is the method of choice for localizing the lesion and determining the extent of involvement. The CT features are non-specific but are highly suggestive in the proper clinical setting. The most important CT findings consist of: round, oval or elongated lobular masses, commonly in the extraconal space, with intraconal extension in large tumors. In some lesions, linear infiltrates radiate from the bulk of the mass into the adjacent fascial compartments. Tumors in proximity to the globe, wrap around the scleral-uveal coat causing no indentation but displacement of the globe from the mass effect. Similar molding occurs along the orbital walls, especially laterally from extraconal lesions. Bone destruction or remodeling of bone is rarely seen in orbital lymphoma. No diagnostic enhancement patterns were observed following contrast infusion. The majority of lymphoid tumors were situated anteriorly and superiorly.

Adult↗
PubMed1985

Alanine synthesis from glyceraldehyde and ammonium ion in aqueous solution.

Alanine is formed under anaerobic conditions from glyceraldehyde and ammonium ion in aqueous solutions of sodium phosphate (pH 7.0) or imidazole-imidazolium chloride (pH 7.0) at ambient temperature. In 500 mM imidazole (pH 7.0), alanine synthesis from 10 mM glyceraldehyde and 15 mM ammonium ion is roughly 6 times more rapid in the presence of 10 mM 3-mercaptopropionate (0.62% yield at 60 days) than in its absence (0.10% yield at 60 days). Likewise, the formation of alanine in 500 mM sodium phosphate (pH 7.0) from 5 mM glyceraldehyde and 10 mM ammonium ion is more rapid in the presence of 10 mM N-acetylcysteine than in its absence. In this reaction with N-acetylcysteine, the ratio of the yield of alanine to the yield of lactate is fairly constant. The yield of alanine is about 4.5% that of lactate. Alanine synthesis in the presence of thiol probably proceeds via alanyl thioester, which is produced by rearrangement of the imine of the hemithioacetal of pyruvaldehyde, a product of glyceraldehyde dehydration. The significance of this reaction for molecular evolution is discussed.

Acetylcysteine↗
PubMed1984

Vocal cord paralysis. A latent effect of perivascular thorium dioxide.

The late effects of thorium dioxide (Thorotrast) in the perivascular space of the neck are reviewed. The roentgenographic analysis of the problem consists of both plain films (to detect the residual density of extravasated thorium dioxide) and computed tomography (to help define any involvement of the carotid artery).

Calcinosis↗
PubMed1984

Prebiotic formation of 'energy-rich' thioesters from glyceraldehyde and N-acetylcysteine.

The 'energy-rich' thioester, N-acetyl-S-lactoylcysteine, is formed from low concentrations of glyceraldehyde and N-acetylcysteine under anaerobic conditions at ambient temperature in aqueous solutions of sodium phosphate (pH 7.0). Reactions with 2 mM glyceraldehyde, 2 mM N-acetylcysteine, and 500 mM sodium phosphate (pH 7.0) convert about 3%/day of the glyceraldehyde to lactoyl thioester. The formation of lactoyl thioester in similar reactions with 500 mM imidazole hydrochloride (pH 7.0) is supported by the thiol-dependence of lactate formation, which is 3-fold greater in the presence of thiol (0.11%/day) than in the absence of thiol (0.04%/day). The formation of lactoyl thioester is thought to proceed by the phosphate (or imidazole)-catalyzed dehydration of glyceraldehyde to give pyruvaldehyde, which adds to the thiol to form a hemithioacetal that rearranges to the thioester. A limited amount of a second thioester, N-acetyl-S-glyceroyl-cycsteine, is also formed at the beginning of these reactions. The significance of these reactions to the origin of life is discussed.

Acetylcysteine↗
PubMed1984

Nonenzymatic formation of "energy-rich" lactoyl and glyceroyl thioesters from glyceraldehyde and a thiol.

The "energy-rich" thioester, N-acetyl-S-lactoylcysteine, is formed under anaerobic conditions from glyceraldehyde and N-acetylcysteine at ambient temperature in aqueous solutions of sodium phosphate (pH 7.0). The conversion of glyceraldehyde to lactoyl thioester occurs at a rate of about 0.4%/day in reactions with 10 mM glyceraldehyde, 10 mM thiol, and 500 mM sodium phosphate (pH 7.0). Thioester formation proceeds at an estimated efficiency of 76%, since a similar reaction with 12.5 mM thiol yields 50.7% lactate at 6 months from only 66.5% of the glyceraldehyde (or its isomer, dihydroxyacetone). The formation of lactoyl thioester most likely occurs by the phosphate-catalyzed dehydration of glyceraldehyde to give pyruvaldehyde, which combines with thiol to form a hemithioacetal that rearranges to the thioester. A second energy-rich thioester, N-acetyl-S-glyceroylcysteine, is also produced from glyceraldehyde when these reactions are carried out in the presence of oxygen and to a limited extent in the absence of oxygen. In the presence of oxygen the formation of glyceroyl thioester continues until the thiol disappears completely by oxidation. The significance of these reactions to the energetics of the origin of life is discussed.

Acetylcysteine↗
PubMed1984

Respiratory disease in tungsten carbide production workers.

We carried out a medical and environmental survey to evaluate respiratory disease at two tungsten carbide (TC) production plants. The study population of 290 subjects (19.2 percent of the total work force) was chosen to focus on those with the greatest potential exposures to cobalt, a binding agent which is probably the cause of interstitial fibrosis and airways disease in TC workers. We found peak air concentrations of cobalt exceeding 500 micrograms/m3 during many major steps in TC production. Nine subjects at plant A and two at plant B had interstitial infiltrates. Two of these nine from plant A had restriction (total lung capacity less than 80 percent of predicted). A lung biopsy specimen in one showed interstitial fibrosis. Two nonsmokers at plant A and one nonsmoker at plant B had obstructive defects. These results suggest that interstitial and obstructive lung disease occur in TC workers in association with elevated peak air concentrations of cobalt.

Adult↗
PubMed1983

Sphenoid sinusitis. A review of 30 cases.

We studied 30 patients with infectious sphenoid sinusitis (15 acute cases and 15 chronic cases) in an effort to characterize the clinical presentation, bacteriology, and associated complications of this frequently misdiagnosed infection. Severe frontal, temporal, or retro-orbital headache that radiated to the occipital regions or pain in the trigeminal (V1 to V3) distribution or both were the most prominent presenting symptoms. In acute cases, purulent exudate was frequently seen in the middle and superior nasal turbinates. Computerized axial tomography or sinus tomography and cannulation of the sphenoid sinus proved to be the most useful diagnostic studies. Organisms detected in acute cases included streptococci other than Streptococcus pneumoniae (41 per cent), Staphylococcus aureus (29 per cent), and Str. pneumoniae (17 per cent). In chronic infections, gram-negative bacilli (43 per cent) and staphylococcal species (24 per cent) were the predominant organisms. In acute disease, early diagnosis and aggressive therapy, including surgical drainage, were important. Delay in treatment was always associated with serious morbidity or mortality. Fatal complications included cavernous sinus thrombosis and bacterial meningitis.

Anti-Bacterial Agents↗
PubMed1983

Thiol-catalyzed formation of lactate and glycerate from glyceraldehyde.

The formation of lactate from glyceraldehyde is catalyzed by the thiol, N-acetylcysteine, at ambient temperature in aqueous sodium phosphate (pH 7.0). The rate of lactate formation is more rapid at higher concentrations of sodium phosphate and is essentially the same in the presence and absence of oxygen. The formation of lactate is efficient, but proceeds slowly with an 8.8% yield of lactate after 16 days from 10 mM glyceraldehyde in the presence of 12.5 mM N-acetylcysteine and 500 mM sodium phosphate (pH 7.0). The formation of glycerate from glyceraldehyde, that occurs in the presence of oxygen and to a small extent when oxygen has been removed, is also catalyzed by the thiol, N-acetylcysteine, under the same conditions. The dramatic increase in the rate of glycerate formation that is brought about by the thiol, N-acetylcysteine, is accompanied by an equally dramatic decrease in the rates of production of glycolate and formate. Presumably, the thiol-dependent formation of lactate and glycerate occurs via their respective thioesters. The significance of these reactions to molecular evolution is discussed.

Acetylcysteine↗