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Biomedical subjects

S A Ross

Publications and source records attributed to S A Ross.

At least 19 recordsLinked to original sources
PubMed1990

A novel sialidase which releases 2,7-anhydro-alpha-N-acetylneuraminic acid from sialoglycoconjugates.

The leech (Macrobdella decora) was found to contain two sialic acid-cleaving enzymes: an ordinary sialidase and a novel sialic acid-cleaving enzyme. This novel enzyme released 2,7-anhydro-alpha-N-acetylneuraminic acid (Neu2,7-anhydro5Ac) instead of alpha-N-acetylneuraminic acid (Neu5Ac) from 4-methylumbelliferyl-Neu5Ac, glycoproteins, and gangliosides. We have partially purified this novel sialidase from M. decora. We have also isolated Neu2,7-anhydro5Ac released from 4-methylumelliferyl-Neu5Ac and whale nasal keratan sulfate in pure form. The novel sialidase produced Neu2,7-anhydro5Ac only from sialoglycoconjugates, but not from free Neu5Ac. The structure of Neu2,7-anhydro5Ac produced by the novel sialidase was established by chemical analysis, mass spectrometry, and NMR spectroscopy. NMR analysis showed that instead of the original 2C5 conformation, the pyranose ring of Neu2,7-anhydro5Ac was in the 5C2 conformation, which makes the formation of the 2,7-anhydro bridge possible.

Animals↗
PubMed1990

Phosphorylation of the polymeric immunoglobulin receptor required for its efficient transcytosis.

The endosomal compartment of polarized epithelial cells is a major crossroads for membrane traffic. Proteins entering this compartment from the cell surface are sorted for transport to one of several destinations: recycling to the original cell surface, targeting to lysosomes for degradation, or transcytosis to the opposite surface. The polymeric immunoglobulin receptor (pIgR), which is normally transcytosed from the basolateral to the apical surface, was used as a model to dissect the signals that mediate this sorting event. When exogenous receptor was expressed in Madin-Darby Canine Kidney (MDCK) cells, it was shown that phosphorylation of pIgR at the serine residue at position 664 is required for efficient transcytosis. Replacement of this serine with alanine generated a receptor that is transcytosed only slowly, and appears to be recycled. Conversely, substitution with aspartic acid (which mimics the negative charge of the phosphate group) results in rapid transcytosis. It was concluded that phosphorylation is the signal that directs the pIgR from the endosome into the transcytotic pathway.

Alanine↗
PubMed1990

Recreational sun exposure in Puerto Rico: trends and cancer risk awareness.

Persons who sunbathe or engage in other activities at the beach are exposed to large amounts of UV radiation. Four hundred seven adults who visited the beaches of Puerto Rico were surveyed to determine their knowledge about the risks of sun exposure and to evaluate sunscreen use. The group consisted of 195 year-round Puerto Rican residents and 212 tourists. Ninety-five percent believed that the sun can cause skin cancer, although only half of the subset who lived all year in Puerto Rico believed that they personally received enough exposure to be at risk. The majority of the group (83%) understood the meaning of the sun protection factor numbers, although 35% used either nothing or a nonscreening oil. Half of Puerto Rican residents rarely or never used sunscreen protection while sunbathing. When sunscreen was used, the most important factor sought was given as sun protection factor (64%), followed by a perceived ability to aid in tanning (26%).

Adult↗
PubMed1990

Immediate heparinisation and surgery in the management of saddle embolism.

Twenty-six patients (age range 40-88 years) with saddle embolism, representing 11% of cases of peripheral embolism, were treated during an 8-year period. A proven intra-cardiac source, including atrial fibrillation and post-infarction mural thrombosis, was observed in 22 cases (85%). The ambiguities in the clinical presentation of saddle embolism were sometimes responsible for delayed recognition. On confirmation of the diagnosis an IV heparin regime was immediately commenced followed by surgery. Our practice of initiating treatment of saddle embolism with immediate systemic heparin infusion resembles that of Blaisdell et al. In contrast, we also advocate a policy of early surgical intervention. Bilateral trans-femoral explorations were undertaken in 21 cases and direct aorto-iliac procedures in five cases. Recurrent embolism occurred in 27% of cases despite postoperative anticoagulant therapy. An overall limb salvage rate of 88.5% was recorded. The postoperative mortality of 30% was accounted for by primary cardiac disease and multiple organ failure. The influence of multiple and recurrent embolism and cardiac instability on the eventual outcome is signifcant. A policy of early systemic heparin therapy and surgery in the management of saddle embolism, enhances limb survival and prevents renal failure.

Adult↗
PubMed1990

Spirochetal forms in the dermal lesions of morphea and lichen sclerosus et atrophicus.

Morphea and lichen sclerosus et atrophicus are cutaneous diseases that are manifest by an early edematous stage, followed later by sclerosis and atrophy. They share features with acrodermatitis chronica atrophicans and erythema chronicum migrans, diseases that have been linked to infection by the spirochete Borrelia burgdorferi. A modified silver stain was used to identify the presence of spirochetes in skin biopsy specimens of patients with morphea and lichen sclerosus et atrophicus. Spirochetal forms were identified in the lesional skin of 10 of 25 patients with morphea and in 10 of 21 cases of lichen sclerosus et atrophicus. These spiral forms of bacteria had a significant tendency to occur in early and fully developed lesions of morphea and in early lesions of lichen sclerosus et atrophicus, whereas they tended to be absent in lesions demonstrating late pathological changes.

Atrophy↗
PubMed1989

Immunologic studies of patients with diabetes mellitus who have received long term insulin therapy: lymphocyte reactivity to insulin is correlated with impaired immunoglobulin secretion in vitro.

To investigate the influence of chronic antigen stimulation on immune response, 31 diabetics who had been treated from 4 to 39 years with various types of insulin were studied. Of the 31 patients, 22 had an elevated lymphocyte blastogenic response to insulin (beef/pork regular or protamine containing types). There were approximately equal numbers of patients with insulin dependent and noninsulin dependent diabetes whose lymphocytes reacted to the insulin. Of 24 patients who were also studied for the ability of their lymphocytes to secrete immunoglobulin secondary to pokeweed mitogen, 14 were significantly depressed compared to normal controls. Depressed responses tended to occur in both IgG and IgM secretion. Average immunoglobulin secretion of the diabetics' lymphocytes was 1843 and 2667 ng/ml, whereas for the normal subjects, the lymphocyte secretion was 3175 and 6013 ng/ml of IgG and IgM, respectively. (The normal secretion was based on the testing of 64 normal individuals.) Interestingly, 13 of 14 patients with impaired immunoglobulin secretion had a positive lymphocyte proliferative response to insulin (P less than 0.01). This statistically significant correlation between lymphocyte proliferative response to insulin and impaired polyclonal immunoglobulin secretion suggests the possibility that chronic antigen stimulation by insulin alters the normal immune response.

Antibody Formation↗
PubMed1989

Sorting signals.

Explore the source record for details and available documents.

Animals↗
PubMed1988

Acquired renal insufficiency in critically ill patients.

We undertook a study to determine the frequency, predisposing factors, and outcome in 315 patients admitted to a medical-surgical ICU, of whom 47 (14.9%) subsequently acquired renal insufficiency (ARI) during their stay in the unit. Four well-recognized risk factors for ARI were present alone or in combination in all episodes: hypotension, sepsis, aminoglycoside antibiotics, and radiocontrast dye. Hypotension was the most prevalent factor, present in 42 (85.8%) episodes, and was the sole factor present in 18 (36.7%). Patients with ARI but without hypotension all survived their ICU stay, while only 13 (33%) of 40 with hypotension survived (p less than .05). Neither initial, peak nor change in BUN or creatinine predicted mortality; oliguria was marginally associated with poor prognosis. Our findings indicate that: a) ARI was a frequent and important contributing factor to mortality in our critically ill patients, b) hypotension was the most common of well-recognized risk factors, and c) conditions that predisposed to ARI also predisposed to mortality, although mortality did not appear to depend on the severity of renal insufficiency.

Acute Kidney Injury↗