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Biomedical subjects

B A Stevens

Publications and source records attributed to B A Stevens.

10 recordsLinked to original sources
PubMed2001

The carboxyl terminus of Dictyostelium discoideum protein 1I encodes a functional glycosyl-phosphatidylinositol signal sequence.

The 1I gene is expressed in the prespore cells of culminating Dictyostelium discoideum. The open reading frame of 1I cDNA encodes a protein of 155 amino acids with hydrophobic segments at both its NH(2)- and COOH-termini that are indicative of a glycosyl-phosphatidylinositol (GPI)-anchored protein. A hexaHis-tagged form of 1I expressed in D. discoideum cells appeared on Western blot analysis as a doublet of 27 and 24 kDa, with a minor polypeptide of 22 kDa. None of the polypeptides were released from the cell surface with bacterial phosphatidylinositol-specific phospholipase C, although all three were released upon nitrous acid treatment, indicating the presence of a phospholipase-resistant GPI anchor. Further evidence for the C-terminal sequence of 1I acting as a GPI attachment signal was obtained by replacing the GPI anchor signal sequence of porcine membrane dipeptidase with that from 1I. Two constructs of dipeptidase with the 1I GPI signal sequence were constructed, one of which included an additional six amino acids in the hydrophilic spacer. Both of the resultant constructs were targeted to the surface of COS cells and were GPI-anchored as shown by digestion with phospholipase C, indicating that the Dictyostelium GPI signal sequence is functional in mammalian cells. Site-specific antibodies recognising epitopes either side of the expected GPI anchor attachment site were used to determine the site of GPI anchor attachment in the constructs. These parallel approaches show that the C-terminal signal sequence of 1I can direct the addition of a GPI anchor.

Amino Acid Sequence↗
PubMed1996

Opioid regulation of intracellular free calcium in cultured mouse dorsal root ganglion neurons.

Opioid agonists induced an increase in the intracellular free calcium concentration ([Ca2+]i) or an inhibition of K+ (25 mM)-stimulated increase in [Ca2+]i in different subsets of mouse dorsal root ganglion (DRG) neurons. The total neuronal population was grouped into three classes according to somatic diameter and defined as small ( < 16 microns), intermediate (16-25 microns), or large ( > 25 microns) neurons. Substance P-like immunoreactivity was detected mainly in the small and intermediate neurons. The delta, kappa, and mu opioid receptor agonists [D-Ser2,Leu5]enkephalin-Thr (DSLET), U69593, and [D-Ala2, MePhe4, Glyol5]enkephalin (DAMGO) each induced a transient increase in [Ca2+]i in a small fraction ( < 30%) of neurons. The increases in [Ca2+]i were blocked by the opioid antagonist naloxone. The dihydropyridine-sensitive calcium channel blocker nifedipine also blocked the increase in [Ca2+]i induced by 1 microM DSLET. The rank order of potency (percentage of cells responding to each opioid agonist) was DSLET > U69593 > DAMGO. The opioid-induced increase in [Ca2+]i was observed mainly in large neurons, with a low incidence in small and intermediate neurons. Opioid agonists also caused inhibition of K(+)-stimulated increases in [Ca2+]i, which were blocked by naloxone (1 microM). Inhibition of the K(+)-stimulated increase by 1 microM DSLET or U69593 was greater in small and intermediate neurons than in large neurons.

Analgesics↗
PubMed1995

Total body potassium and serum potassium among eating disorder patients.

OBJECTIVE: The purpose of the study was to determine body composition, including total body potassium (TBK+), serum potassium, and lean body mass (LBM), in anorexia nervosa. METHOD: TBK+ measurements, serum potassium levels, and anthropometric measurements were obtained from four anorectic patients in the first week after their hospital admission. All four patients had normal serum potassium levels but three of the four had significant depletion of total body potassium. Two methods of calculating LBM, based on TBK+ measures or anthropometric assessment, produced different results. RESULTS: TBK+ may be depleted even when serum potassium levels are normal. It was also concluded that the two methods of calculating LBM were inaccurate. DISCUSSION: Patients may be at risk for cardiac arrhythmias and other physiological abnormalities even when serum potassium is normal since TBK+ may be low. The need for comprehensive assessment of body composition based on four compartment models is discussed.

Adult↗
PubMed1993

A randomized clinical trial of two different durations of oral cryotherapy for prevention of 5-fluorouracil-related stomatitis.

BACKGROUND: The authors previously reported that 30 minutes of oral cryotherapy inhibits 5-fluorouracil (5-FU)-induced stomatitis. The current trial was designed to determine whether a longer duration of cryotherapy would provide additional protection. METHODS: This trial involved patients who were receiving their first course of a 5-FU plus leucovorin chemotherapy regimen, for which stomatitis is a major dose-limiting toxicity. These patients were randomized to receive either 30 or 60 minutes of oral cryotherapy given at around the same time as the 5-FU therapy. RESULTS: A total of 178 evaluable patients were studied. Both cryotherapy groups had similar degrees of mucositis. CONCLUSION: The authors continue to recommend the use of 30 minutes of oral cryotherapy for patients receiving bolus intensive courses of 5-FU-based chemotherapy.

Adult↗
PubMedDate not supplied

Other psychiatric disorders among bulimic patients.

Clinical experience suggests that bulimia nervosa is a disorder often accompanied by additional psychiatric symptoms. Based on unstructured clinical interviews, 21 additional Axis I and six Axis II diagnoses were assigned to a sample of 30 bulimic women. The Structured Clinic Interview for DSM-III-Patient Version (SCID-P) generated 47 additional Axis I and 78 Axis II diagnoses. There was little agreement across measures in the assessment of mood disturbance. These results not only suggest a greater degree of pathology in bulimic women, but also raise important questions regarding the measurement and conceptualization of DSM-III-R Axis II disorders.

Adult↗
PubMedDate not supplied

Safety and efficacy of debridement under anesthesia in patients with burns.

Burn wound debridements requiring blunt or sharp manipulations are extremely painful even when large nonanesthetic doses of morphine are used. In this study we describe the use of debridement while the patient is under anesthesia (DUA) when manipulation of the wound is required. Seventy-one debridements were performed on 46 patients. One patient required additional fluids during the DUA, but no deaths, extensive blood losses, or significant changes in nutrition attributable to the DUA occurred. The mean number of required DUAs was 1.6 per patient compared with 6.0 per patient reported in a previous study from the same burn center that involved standard parenteral analgesic doses of morphine sulfate. Patients were completely anesthetized during the procedure. Therefore, they were free of pain and were amnestic for the experience. We conclude that DUA is a safe, efficacious procedure that permits full relief from the pain usually experienced during a manipulative burn wound debridement.

Adult↗