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Biomedical subjects

H A Schneider

Publications and source records attributed to H A Schneider.

At least 19 recordsLinked to original sources
PubMed1988

Diphosphonate bone scans in patients with polyarthralgias.

Early detection of inflammatory arthropathy is notoriously difficult with standard radiographic techniques. We therefore assessed bone turnover with technetium Tc 99m medronate in 16 patients with persistent polyarthralgias who had no clinical synovitis, normal radiographs, and nondiagnostic results from laboratory evaluations. Abnormal scans were found in 11 of 16; five were unremarkable. Scan abnormality corresponded with symptomatic joints (11 of 11 patients). These 11 patients had normal test results for rheumatoid factor, antinuclear antibody, and HLA-B27. Patients with abnormal scans were treated with nonsteroidal antiinflammatory drugs or analgesics (11 of 11), hydroxychloroquine sulfate (four), or gold salts (one), with improvement (nine of 11); patients with normal scans (five of five) were treated successfully with nonsteroidal antiinflammatory drugs or analgesics and reassurance. One patient with a normal scan developed sarcoidosis; one, hypermobility syndrome; and one, a viral syndrome. Two patients had no diagnosis. Abnormal technetium Tc 99m medronate scans in patients with previously undiagnosed polyarthralgias suggested inflammatory arthropathy and influenced management decisions with favorable therapeutic outcomes.

Adult↗
PubMed1985

Rheumatoid vasculitis: experience with 13 patients and review of the literature.

Rheumatoid vasculitis is an uncommon but potentially catastrophic complication of RA. There are few current extensive experiences and no consensus regarding the clinical, laboratory, histologic features, and management or prognosis of rheumatoid vasculitis. We therefore reviewed selected observations in 13 patients followed over the past decade and compared them with patients reported and with results of a survey of North American Rheumatologists. Our patients were seven men and six women (age, 33 to 70 years) who had had active RA for 4 to 36 years. They exhibited sensory neuropathy, mononeuritis multiplex, Felty syndrome, cutaneous lesions, leg ulcers, gangrene, anemia, leukocytosis, eosinophilia, high titers of RF, hypocomplementemia, and CICs or cryoglobulinemia approximately as frequently as other reported patients with rheumatoid vasculitis, but they displayed constitutional symptoms, subcutaneous nodules, ischemic changes, and proteinuria rather less consistently than in other series. These observations were not necessarily as expected by survey respondents. We, as in other series and suggested by survey respondents, tended to select penicillamine or cytotoxic drugs (or plasmapheresis) for patients with mononeuritis, gangrene, or leg ulcers, and nonsteroidal antiinflammatory drugs, antimalarials, gold, or penicillamine for sensory neuropathy or digital lesions. Four patients died, two deteriorated, and seven were stable or improved, a finding that was also similar to the experiences of others. Rheumatoid vasculitis is an uncommon, potentially catastrophic syndrome with varying clinico-pathologic features that have different prognostic implications and should be managed individually.

Adult↗
PubMed1983

Molecular properties of 5-aminolevulinic acid dehydratase from Spinacia oleracea.

5-Aminolevulinic acid dehydratase from spinach (Spinacia oleracea), highly purified by immunoprecipitation, was characterized by inhibitor studies, amino acid composition, the mode of substrate binding and electron photomicrography. The results show that the conversion of 5-aminolevulinate to porphobilinogen requires an active arginine residue and the formation of a Schiff base between the enzyme and 5-aminolevulinate. The formation of a Schiff base is well known for bacterial and animal dehydratases. Spinach dehydratase, however, is distinguished by its insensitivity to iodoacetamide, a low content of cysteine residues and a high proportion of acidic amino acids. In addition, electron photomicrographs of spinach dehydratase molecules do not resemble the corresponding images of beef liver dehydratase. The finding that an arginine residue is essential for substrate conversion corroborates the suggestion that the right orientation of the substrate in the active center is dependent on a positive charge.

Amino Acids↗
PubMed1978

Light-induced, Dark-reversible Absorbance Changes in Roots, Other Organs, and Cell-free Preparations.

Irradiation of maize (Zea mays) roots and coleoptiles with visible light causes dark-reversible absorbance changes in these organs. There is an increase in absorbance near 440 nanometers and smaller increases below 410 nanometers and about 595 nanometers. Decreases in absorbance are observed at about 420 nanometers and minor ones at 537 and 575 nanometers. These responses are also observed in cell-free preparations from roots and coleoptiles if dithionite, NADPH, or NADH is added prior to illumination. The dose curve for these effects has a distinct maximum at 420 nanometers and a minor one at 575 nanometers. Difference spectra and dose response curves indicate that heme compounds such as cytochromes or, more probably, peroxidase complexes are the photoreceptive and chemical reacting molecules. Siroheme-containing proteins may also be taken into consideration.The light-induced absorbance changes have half-lives of more than 200 seconds and 100 seconds in roots of maize and soybean, respectively. Two reactions, each with first order kinetics, appear to be superimposed. The respective rate constants for maize roots are about 0.004 and 0.04 seconds(-1). The generation of the effect has a much shorter half-life dependent on light intensity and wavelength. Little deviations from first order kinetics were detected. Rate constants for corn roots range between 0.05 and 0.01 seconds(-1).Apart from the problem in which hemoproteins are involved, there is the problem of correlating the reaction of the photoreactive and chemically reacting molecules to macroscopic responses such as phototropism.

Journal Article↗
PubMed1977

Corneal thickness measurements following intraocular lens implantation.

Corneal thickness measurements were carried out on patients who had undergone combined phacoemulsification cataract extraction with simultaneous intraocular lens implantation in one eye at least six months prior to the date of measurement. The unoperated eye served as control. Another group of patients who had undergone simultaneous phacoemulsification cataract extraction combined with intraocular lens implantation were followed over a two-month period of time, serial corneal thickness measurements being performed. The results indicate that, in surgery performed by experienced surgeons on carefully selected patients, phacoemulsification cataract extraction using the Kelman technique combined with intraocular lens implantation had no significant effect on corneal endothelial function as reflected in corneal thickness changes.

Aged↗
PubMed1975

Control of salmonellosis pacifarin biosynthesis by iron.

Enterobacter cloacae strain SS4-56 produced salmonellosis pacifarins when grown in an iron-depleted synthetic medium to which 3.16 X 10-7 g-atom of iron had been added per liter, but did not do so when grown in iron-depleted medium supplemented with 3.16 X 10-4 g-atom of iron per liter. The addition of 3.16 X 10-4 g-atom of ferric iron per liter to a pacifarin-containing culture supernatant fluid had no significant effect upon the ability of the active pacifarins present, when administered per os, to protect mice from an otherwise fatal infection produced by a sequential injection of avirulent and virulent strains of Salmonella typhimurium.

Animal Feed↗
PubMed1975

Combined Kelman procedure (phaco-emulsification cataract extraction) and simultaneous aphakic penetrating keratoplasty.

The problem of management of coexistent lenticular and corneal opacification is, as yet, unresolved. Combined intracapsular cataract extraction and penetrating keratoplasty affords the risk of vitreous loss at the time of surgery or perhaps the even greater risk of vitreous adhesion to the donor cornea. Leaving an intact posterior capsule would certainly avoid the problems of vitreous touch. Where applicable, we have been utilizing the technique of combined phaco-emulsification cataract extraction followed by aphakic penetrating keratoplasty leaving an intact posterior capsule and removing all cortical remnants with the irrigation-aspiration probe of the Kelman Cavitron unit. This technique has proved extremely useful in our hands and we suggest that it is a useful alternative in the management of coexistent lenticular and corneal opacification.

Cataract Extraction↗