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Biomedical subjects

R E Smith

Publications and source records attributed to R E Smith.

At least 307 records · Page 17Linked to original sources
PubMed1987

Epidemiology of microbial keratitis in southern California. A multivariate analysis.

Two hundred twenty-seven cases of microbial keratitis reported in nonreferral county practice were studied. The staphylococci, Pseudomonas aeruginosa and Streptococcus pneumoniae, were the major isolates. A multivariate statistical model was developed to evaluate possible predisposing and outcome determinants. Several racial and age-related relationships were shown. The interaction of numerous local ocular and systemic factors played a fundamental role in causing disease. The authors found significant association between S. pneumoniae and topical steroid use, and direct and indirect linkage of S. aureus with diabetes and trauma, respectively. S. pneumoniae and Moraxella were risk factors for major complications (24% of cases); S. pneumoniae was related to enucleation and late perforation. Corneal exposure and prior topical steroids were associated with prolonged hospital stays. Hypopyon was associated with pneumococcal infection, 60 years of age or older, and trauma. The identification of groups at high-risk for microbial keratitis and problems of preventive management are discussed.

Bacterial Infections↗
PubMed1987

Oval host wounds and postkeratoplasty astigmatism.

Penetrating keratoplasty frequently results in postoperative astigmatism. A rabbit model was used to investigate the relationship between the ovality of the recipient bed and the resulting postoperative astigmatism as measured by keratometry. Animals were grouped based on the extent that the recipient bed deviated from a 7.25-mm diameter circle (ovality of bed). All animals received a round 7.75-mm donor corneal button. With increasing ovality of the recipient bed, there was a corresponding increase in the postoperative astigmatism at 3 months after all sutures were removed.

Animals↗
PubMed1987

Peripheral vascular effects of beta-adrenoceptor blockade: comparison of two agents.

1. The effects of atenolol (100 mg), a beta 1-adrenoceptor blocker, and bevantolol (200 mg) were compared on heart rate, blood pressure, lung function and on the peripheral circulation in normal volunteers before and after isoprenaline infusion. Recordings were obtained 2 and 24 h following a single dose and 24 h after continuous dosage for 7 days. 2. The effect of atenolol on the blockade of beta-adrenergic stimuli, as measured by the ability to reduce isoprenaline-induced tachycardia, was greater than that of bevantolol. Though both drugs achieved a similar reduction in systolic pressure there was a significantly greater reduction in diastolic pressure with bevantolol. The lung function tests gave similar results to those with other beta-adrenoceptor blockers. 3. Atenolol produced a fall in peripheral blood flow consistent with unopposed peripheral alpha-adrenoceptor stimulation. The effect of bevantolol differs from that of atenolol, an initial fall in peripheral blood flow being followed by a rapid recovery to baseline or greater. This effect may be due to partial alpha-adrenoceptor agonist activity.

Adrenergic beta-Antagonists↗
PubMed1987

Factors affecting the secretion of submandibular salivary kallikrein in cats.

Glandular kallikrein has been assessed in submandibular saliva, homogenates and plasma by the fluorimetric substrate D-Val-Leu-Arg-7-amino-4-trifluoromethylcoumarin (AFC) and histochemically in tissue sections by the 4-methoxy-2-naphthylamide (MNA) analogue. Nerve stimulation was used to produce salivary secretion. Parasympathetic saliva contained low concentrations of kallikrein, independently of any circulating catecholamines from the adrenals. Sympathetic saliva contained very high concentrations of kallikrein; the amounts in individual drops rapidly reached a peak then declined gradually. Adrenergic blocking drugs during mixed parasympathetic and sympathetic stimulation showed that beta-adrenergic effects normally increase the secretion of kallikrein in response to the alpha-adrenergic influence from sympathetic nerve impulses. Small amounts of a glandular kallikrein-like activity are present in the plasma. Effluent blood from the submandibular gland before, during and after stimulation of either nerve gave no indication that submandibular kallikrein passes from the glandular compartment to the blood under conditions of unobstructed salivary flow. Excision of the chorda tympani indicated that parasympathetic nerve impulses are required for the normal resynthesis of submandibular kallikrein. The secretion of salivary kallikrein is essentially an exocrine function but its role in the saliva remains obscure. The results suggest that sudden mobilization of kallikrein may occur at times into the saliva and that a separate population of adrenergic axons, under separate central control, may pass to the striated ducts specially for this purpose.

Animals↗
PubMed1987

Genetic determinants of neoplastic diseases induced by a subgroup F avian leukosis virus.

Two subgroup F avian leukosis viruses, ring-necked pheasant virus (RPV) and RAV-61, were previously shown to induce a high incidence of a fatal proliferative disorder in the lungs of infected chickens. These lung lesions, termed angiosarcomas, appear rapidly (4 to 5 weeks after infection), show no evidence of proto-oncogene activation by proviral integration, and are not induced by avian leukosis viruses belonging to other subgroups. To identify the viral sequences responsible for induction of these tumors, we constructed recombinant viruses by exchanging genomic segments of molecularly cloned RPV with those of a subgroup A leukosis virus, UR2AV. The ability to induce rapid lung tumors segregated only with the env sequences of RPV; the long terminal repeat of RPV was not required. However, recombinants carrying both env and long terminal repeat sequences of RPV induced lung tumors with a shorter latency. In several cases, recombinant viruses exhibited pathogenic properties differing from those of either parental virus. Recombinants carrying the gag-pol region of RPV and the env gene of UR2AV induced a high incidence of a muscle lesion termed infiltrative intramuscular fibromatosis. One recombinant, EU-8, which carries the gag-pol and LTR sequences of RPV, and the env gene of UR2AV, induced lymphoid leukosis after an unusually short latent period. The median time of death from lymphoid leukosis was 6 to 7 weeks after infection with EU-8 compared with approximately 5 months for UR2AV.

Animals↗
PubMed1987

Post-traumatic and postoperative endophthalmitis: a comparison of visual outcomes.

We retrospectively studied 50 consecutive cases of exogenous endophthalmitis treated between 1972 and 1985. Twenty-two of these cases occurred after penetrating ocular trauma and the remaining 28 followed ocular surgery. Thirty-two (64%) of the cases were culture-positive. A wide variety of organisms were identified in the post-traumatic cases, while the isolated agent in the majority of postoperative cases was Staphylococcus epidermidis. Twenty-nine of the 50 patients received treatment with vitrectomy and intraocular antibiotics; of these, 14 (48%) achieved final visual acuities better than or equal to 20/400. Of the 21 patients who were treated with parenteral, topical, and subconjunctival antibiotics alone eight (38%) reached this same final visual acuity. Culture-negative cases, postoperative cases, and cases treated with vitrectomy and intraocular antibiotics were associated with improved visual outcomes.

Adolescent↗
PubMed1987

Effects of carbon dioxide on mental performance.

Although elevated levels of inspired CO2 have been recorded in work situations, little is known about effects of concentrations greater than 6% on mental performance. We have measured the effects of inhaling 0, 4.5, 5.5, 6.5, or 7.5% CO2 for 20 min on normal young adults unhabituated to CO2. Performance of reasoning tasks, such as AB logic problems, was significantly slowed at the higher levels of CO2, with a threshold at end-tidal PCO2 close to 51 Torr. Accuracy of reasoning and short-term memory were not significantly affected. More prolonged studies with inhalation of 6.5% CO2 showed that after the first 10 min ventilation tended to increase, end-tidal PCO2 to fall, and slowing of reasoning to recover, but substantial decrement in performance continued for 80 min, by which time performance virtually stabilized. On return to air breathing, preexposure performance was resumed within 10 min. Also caused by 6.5% CO2 was a significant rise in subjectively assessed irritability and discomfort, with no significant change in alertness or in either registration or recall of long-term memory.

Adult↗
PubMed1987

Selection of a simple protease procedure for identifying mast cells in routinely processed human tissues.

Proteases present in mast cell granules have been harnessed to demonstrate mast cells in human tissues. A number of substrate mixtures were tested. D-Val-Leu-Arg-4-methoxy-2-naphthylamide (MNA) plus Fast Blue B was the best for identifying human mast cells, yielding the most specific and complete staining. The procedure is simple and the results are permanent. Cryostat sections of aldehyde-fixed routine preparations or paraffin sections of Carnoy-fixed tissues give the most satisfactory results. Mast cells are stained a strong red color that stands out distinctly from the surrounding tissues, so that they can be easily identified by simple microscopy. A double-staining technique, first for protease and subsequently using Alcian Blue, showed that as progressive protease staining occurs, the alcianophilia of mast cells is lost. This procedure demonstrated that mast cells in the mucosa of human gut generally required longer incubations to develop protease staining than in other connective tissue sites. In post-mortem tissues, mast cells retain their protease activity well and so can be demonstrated in cryostat sections of aldehyde-fixed material, giving a more complete picture than with Alcian Blue. The synthetic substrate D-Val-Leu-Arg-MNA can be recommended for routine identification of mast cells in human tissues.

Alcian Blue↗
PubMed1987

Immunopathology of acute experimental histoplasmic choroiditis in the primate.

The immunopathologic features of experimental acute histoplasmic choroiditis were studied in the nonhuman primate. Using an indirect immunoperoxidase technique, a panel of hybridoma-derived anti-human monoclonal antibodies, recognizing distinct lymphoid cell and macrophage surface antigens, have been adapted for use in the primate system. Twenty-two individual foci of histoplasmic choroiditis from five eyes were studied at time periods from 20 to 60 days post intracarotid injection of yeast phase Histoplasma capsulatum. A mononuclear and granulocytic cell infiltration was seen in all lesions. The predominant cell type was the CAPPEL+ T lymphocyte (suppressor/cytotoxic subset). Other cell types found in smaller numbers were OKT4+ T cells (helper/inducer subset), OK7+ (peripheral B lymphocytes), IgD+ (mantle B cells) and OKM1+ cells (macrophages and polymorphonuclear leukocytes). Herein, we present immunopathologic data on the acute phase of experimental ocular histoplasmosis.

Acute Disease↗
PubMed1987

Pseudophakic keratoplasty: posterior chamber lens implantation in the presence of ruptured capsule.

A technique is described for implantation of a posterior chamber intraocular lens during keratoplasty for bullous keratopathy when a large capsulotomy and vitreous prolapse are present. Seven cases of pseudophakic or aphakic bullous keratopathy with anterior chamber, iris-fixated, or no intraocular lens in place are reported. A completely intact posterior capsule is not necessary to support safely a sulcus-fixated posterior chamber lens. Anterior segment reconstruction, careful removal of existing intraocular lenses (except a posterior chamber lens), vitrectomy through the ruptured posterior capsule, and assessment of the remaining posterior capsule rim are important surgical objectives.

Aphakia, Postcataract↗
PubMed1987

Dietary fat and breast cancer.

This paper reviews the relationship between dietary fat and breast cancer. The incidence of breast cancer is discussed with regard to dietary habits, geographic location, and economic status. The roles of Trans-fatty acids and urinary as well as plasma estrone, estradiol (E2), estriol (E3), and estrogen are reviewed. Specific hypotheses are proposed to explain the relationship between fatty acid intake and breast cancer.

Breast Neoplasms↗
PubMed1987

Dual fluorometric/colorimetric detection system for an automated random-access instrument utilizing standard polystyrene test tubes as precision cuvettes.

To attain the optical precision necessary to precisely quantify fluorescent or colorimetric signals, analytical systems have typically included quality-controlled cuvettes, flow cells, or dual-beam reference systems. We describe a system where a fluorescence or transmittance signal is quantified in single, standard, 12-mm-diameter polystyrene test tubes. Tube-to-tube variation is minimized by referencing the primary signal to a second reference signal. The tube is carefully oriented within a positioner that allows for the precise placement of the tube within a light path 7.6 mm in diameter. The detection system allows for use of either four pairs of fluorescence excitation/emission wavelengths or eight transmittance wavelengths, which are selected by using specific interference filters. The impact of temperature, tube imperfections, surface flaws, and distortions is minimized by using a reference ratio. Fluorescence is measured with an orthogonal photomultiplier tube, and transmittance with a photodiode; both are illuminated with an ordinary long-life tungsten-halogen lamp. This system is used with the Becton Dickinson AFFINITY system, an automated random-access analyzer with analyte-specific unit-package reagents. The polystyrene tube of the reagent package, which has an antibody-absorbed surface, serves as both the cuvette and the separation medium. Use of the reference ratio method reduces intertube imprecision of fluorometric or transmittance signals, for more precise quantification of various analytes.

Autoanalysis↗
PubMed1987

Chronic anaerobic bacterial endophthalmitis in pseudophakic rabbit eyes.

Experimental anaerobic bacterial endophthalmitis was produced in pseudophakic and aphakic rabbits by using anterior chamber inoculation of 2.5 x 10(6) Propionibacterium acnes organisms. Clinical inflammation was more intense and prolonged in operated eyes with an intraocular lens in place. The presence of an intraocular lens favors the development of chronic low-grade P. acnes-related inflammation.

Animals↗
PubMed1986

Therapy of recurrent squamous cell carcinoma of the head and neck using combination vincristine, bleomycin, and methotrexate. A Southwest Oncology Group Study.

Fifty-six patients with squamous cell carcinoma of the head and neck were treated with the combination of vincristine, bleomycin, and methotrexate (VBM) on an every 2-week schedule. The overall CR + PR rate was 20%. Median response duration was 10 weeks. The toxicity during this trial was comparable to previously reported VBM regimens. The response rate was less than or no better than those previously reported for VBM or methotrexate alone. Therefore, this regimen offers nothing over methotrexate alone or other VBM regimens.

Actuarial Analysis↗
PubMed1986

Mycobacterium chelonei keratitis after radial keratotomy.

Two patients who had undergone radial keratotomy developed delayed postoperative infectious keratitis. Both patients had surgery at the same outpatient facility, and their procedures had been performed by the same surgeon. The corneal lesions appeared similar in both cases, consisting of white irregular infiltrates with radiating projections and fluffy, indistinct margins. Although they were found at all levels, the lesions were most concentrated in the mid-to-deep stroma and were associated with overlying epithelial defects. In both cases, Mycobacterium chelonei was isolated from corneal biopsy specimens. Both patients were treated with topical fortified amikacin; in one there was complete resolution of the corneal infiltrates with medical therapy alone. Although the other patient's lesions initially appeared to resolve with medical therapy, she eventually required corneal transplantation because of recurrence of the infiltrates. Histopathologically, the infiltrates consisted of myriads of acid-fast bacteria with rare inflammatory cell infiltrations.

Adult↗