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Biomedical subjects

G S Young

Publications and source records attributed to G S Young.

At least 19 recordsLinked to original sources
PubMed2006

MR imaging of human herpesvirus-6-associated encephalitis in 4 patients with anterograde amnesia after allogeneic hematopoietic stem-cell transplantation.

MR imaging is typically obtained during the work-up of patients who have undergone allogeneic hematopoietic stem-cell transplant who present with unexplained change in mental status, amnesia, or seizures. Although the differential diagnosis is broad in this setting, the presence of T2 prolongation limited to the medial aspect of one or both temporal lobes with or without associated reduced water diffusion may help limit the possible diagnoses. A frequent etiology seen in this context is human herpesvirus-6 (HHV6) infection. We report the evolution of MR imaging findings and clinical course in 4 patients with limbic encephalitis probably related to HHV6.

Adult↗
PubMed2006

Creutzfeldt-jakob disease involvement of rolandic cortex: a quantitative apparent diffusion coefficient evaluation.

BACKGROUND: Previous reports have suggested that abnormally reduced water diffusivity and T2 prolongation involving cerebral gray matter in patients with early sporadic Creutzfeldt-Jakob disease (sCJD) involves all areas of neocortex with similar frequency, except for primary sensorimotor cortex (Rolandic cortex) and visual cortex. Rolandic cortex often appears to be spared even in the presence of extensive surrounding neocortical signal intensity abnormality in adjacent frontal and parietal gray matter. A quantitative apparent diffusion coefficient (ADC) analysis was designed to investigate whether this unusual pattern results from pathophysiologic sparing of Rolandic cortex or from reduced conspicuity of signal intensity abnormality on MR imaging echo-planar diffusion-weighted images (epiDWI) related to unknown underlying features of Rolandic cortex. METHODS: ADC maps were derived from epiDWI of 6 patients with sCJD and 8 control patients. Bilateral regions of interest were manually selected in precentral gyri, superior frontal gyri, postcentral gyri, supramarginal gyri, thalamus, putamen, and caudate nuclei. ADC and relative ADC (rADC) values were calculated for each region of interest. RESULTS: Patients with CJD had significantly lower ADC values than control patients in all areas (P < or = 0.05). The trend toward decreased ADC values in the deep nuclei correlates well with previously published reports. rADC were not significantly different between CJD and control groups in any area (P > 0.25 in all cases). CONCLUSION: Quantitative ADC measurements in patients with early sCJD demonstrate a similar degree of reduced water diffusivity in the primary somatosensory cortex as in other neocortical areas, despite the normal appearance of these areas on visual inspection of epiDWI.

Aged↗
PubMed2003

Utility of esophageal biopsy in the diagnosis of nonerosive reflux disease.

This study evaluated the accuracy of esophageal biopsy for the diagnosis of nonerosive reflux disease (NERD) in adults. Thirty-five patients with reflux symptoms and a normal endoscopy were prospectively evaluated using esophageal biopsies, 24-h ambulatory pH monitoring and symptomatic response 4 weeks after an increase in antireflux therapy. Biopsies were scored for the total number of typical histologic reflux features seen. Patients were considered to have NERD if both pH-metry was positive and step-up therapy was successful. Biopsies were then compared to this predefined gold standard. Biopsy was most sensitive (62%) but poorly specific (27%) when one or more histologic reflux features were seen. A threshold of three or more histologic features improved the specificity (91%) but reduced sensitivity (31%). Response to step-up therapy was associated with 100% sensitivity and 100% negative predictive value when compared to biopsy and pH-metry as an alternate combined gold standard. In conclusion, biopsy is insensitive in diagnosing NERD but reasonably specific if three or more typical histologic reflux features are present.

Biopsy↗
PubMed1999

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Humans↗
PubMed1999

Urologic applications of the holmium laser.

The holmium laser has various urologic applications. It is important for urologic nurses and associates to be familiar with the laser physics and safety recommendations of the holmium laser, as well as to understand the applications and surgical techniques associated with this therapy.

Holmium↗
PubMed1995

Felinization of the esophagus.

Transient transverse folds of the esophageal mucosa as seen by barium esophagography and on endoscopic examination have been termed "felinization." This finding has been considered a normal variant or has been associated with reflux esophagitis. No symptoms have been associated with its presence. In 280 unselected patients undergoing upper gastrointestinal endoscopy in our clinic, felinization was identified in 24% by prospective visual examination. It was not correlated with sex, age, symptom complex, or common coexistent endoscopic findings. These transverse esophageal folds, although visually interesting, appear to have no clinical significance. The endoscopist should recognize and differentiate them from fixed or persistent folds that can be associated with mucosal disease.

Animals↗
PubMed1995

Lung transplantation in Louisiana: report of the first twenty lung transplants performed in the state.

Lung transplantation is a successful alternative treatment for a variety of end-stage lung diseases. The first 20 lung transplants performed in Louisiana between November 1990 and July 1994 are reported from Ochsner Foundation Hospital. Transplant procedures included 1 heart-lung, 11 bilateral sequential lung, and 8 single-lung transplants in 8 males and 11 females (1 retransplantation). The average age was 38 years (range 7-60), and the median waiting time was 34.5 days (range 1-329). Indications for transplant included emphysema, pulmonary fibrosis, pulmonary hypertension, cystic fibrosis, bronchiectasis, and bronchiolitis obliterans. Overall 1-year and 3-year survival were 65.0% and 58.5%, respectively. Infection was the major cause of morbidity and mortality. Rejection episodes were observed but treated successfully in all 20 patients. Lung transplantation has proved to be a successful treatment for a variety of severely limiting and terminal pulmonary conditions for patients in our state.

Adolescent↗
PubMed1992

Cloning and pharmacological characterization of a human bradykinin (BK-2) receptor.

A human BK-2 bradykinin receptor was cloned from the lung fibroblast cell line CCD-16Lu. The cDNA clone encodes a 364 amino acid protein that has the characteristics of a seven transmembrane domain G-protein coupled receptor. The predicted amino acid sequence of the human BK-2 receptor is 81% identical to the smooth muscle rat BK-2 receptor (1). Transfection of the human BK-2 receptor cDNA into COS-7 cells results in the expression of high levels of specific BK binding sites. Saturation binding analysis indicates that the human BK-2 receptor expressed in COS-7 cells binds BK with a KD of 0.13 nM. Pharmacological characterization of the expressed BK receptor is consistent with the cDNA encoding a receptor of the BK-2 subtype. The BK-2 receptor antagonist Hoe 140 (2), D-Arg0[Hyp3, Thi5, D-Tic7, Oic8]BK has a high affinity (IC50 = 65 pM) for the cloned human receptor. The tissue distribution of the human BK-2 receptor was analyzed by competitive PCR with human tissue cDNA and is similar to that determined for the BK-2 receptor in the rat.

Amino Acid Sequence↗
PubMed1992

Characterization of solubilized bradykinin B2 receptors from smooth muscle and mucosa of guinea pig ileum.

Bradykinin (BK) B2 receptors in guinea pig ileum were characterized in both membrane and soluble form. [3H]BK bound to a single class of sites with almost identical affinities in membranes prepared from the longitudinal muscle, circular muscle and mucosal layers of the ileum. The pharmacology of the binding in the distinct layers was indistinguishable. The detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate (CHAPS) maximally solubilized nearly 80% of membrane binding activity in a very stable conformation. In soluble preparations, [3H]BK labeled a single class of sites but with about 10-fold lower affinity. The affinities of BK analogs in competition studies were similarly reduced. There was no difference in the pharmacology of the binding in soluble receptors prepared from the different layers of the ileum. The results show that the ileum is a good source of solubilized B2 receptors and that the receptors in the smooth muscle and the mucosa are very similar.

Amino Acid Sequence↗
PubMed1992

Bradykinin stimulation of phosphoinositide hydrolysis in guinea-pig ileum longitudinal muscle.

1. Bradykinin (BK)-induced contraction of ileal smooth muscle is assumed to be due to phosphoinositide hydrolysis but this has never been reported. We have investigated whether BK receptors are linked to this transduction mechanism in guinea-pig ileum longitudinal muscle and determined whether these receptors are equivalent to those labelled in [3H]-BK binding assays. 2. In membranes prepared from longitudinal muscle, [3H]-BK bound to a single class of sites with high affinity. Characterization of the binding with BK analogues indicated that the radioligand selectivity labelled a B2 type receptor. 3. BK significantly elevated tissue levels of [3H]-inositol phosphates in longitudinal muscle slices preincubated with [3H]-myo-inositol. The agonists potencies of BK, Lys-BK, Met-Lys-BK, Tyr5-BK and Tyr8-BK were in agreement with their relative potencies in the binding assay. The B1 receptor agonist des-Arg9-BK, did not stimulate inositol phosphate production. The response to BK was blocked by known B2 receptor antagonists but not by the B1 antagonist des-Arg9, Leu8-BK. 4. BK-induced phosphoinositide hydrolysis was unaffected by exposure of muscle slices to either atropine or indomethacin. 5. The results indicate that the B2 receptors linked to phosphoinositide turnover in ileal longitudinal muscle exhibit properties similar to those involved in contractile responses. Also, the receptor mediating the phosphoinositide response is likely to be that labelled in the [3H]-BK binding studies.

Animals↗
PubMed1992

Delayed brain injury after head trauma: significance of coagulopathy.

We reviewed the records of 253 patients with head injury who required serial computed tomographic (CT) scans; 123 (48.6%) developed delayed brain injury as evidenced by new or progressive lesions after a CT scan. An abnormality in the prothrombin time, partial thromboplastin time, or platelet count at admission was present in 55% of the patients who showed evidence of delayed injury, and only 9% of those whose subsequent CT scans were unchanged or improved from the time of admission (P less than 0.001). Among patients developing delayed injury, mean prothrombin time at admission was significantly longer (14.6 vs. 12.6 s, P less than 0.001) and partial thromboplastin time was significantly longer (36.9 vs. 29.2 s, P less than 0.001) than patients who did not have delayed injury. If coagulation studies at admission were normal, a patient with head injury had a 31% risk of developing delayed insults. This risk rose to almost 85% if at least one clotting test at admission was abnormal (P less than 0.001). We conclude that clotting studies at admission are of value in predicting the occurrence of delayed injury. If coagulopathy is discovered in the patient with head injury early follow-up CT scanning is advocated to discover progressive and new intracranial lesions that are likely to occur.

Adolescent↗
PubMed1992

Is hemoglobin level alone a reliable predictor of outcome in the severely anemic surgical patient?

The relationship between outcome and hemoglobin (Hgb), oxygen extraction ratio (ER), history of cardiac, renal, pulmonary, and/or hepatic disease, diabetes, malignancy, sepsis, hypertension, and active bleeding was analyzed in 47 patients with severe anemia (Hgb less than 7.0 gm/dl, mean = 4.6 +/- .2 gm/dl) to evaluate the effect of Hgb on survival and to look for other predictors of outcome. All patients had refused blood transfusion on religious grounds and were participants in a randomized, controlled study of the blood substitute Fluosol DA-20 per cent. Patients were analyzed as a group and after stratifying by Hgb into four levels: (Hgb less than 3.0 gm/dl, N = 7; Hgb less than 3.5 gm/dl, N = 12; Hgb less than 4.0 gm/dl, N = 17; Hgb less than 4.5 gm/dl, N = 23) and by ER into two levels of less than 50 per cent and greater than 50 per cent. Only Hgb, ER, sepsis and active bleeding were predictors of outcome, with sepsis being the only significant, independent predictor of outcome at all levels (P less than .01). Active bleeding was a predictor for levels of Hgb below 4.0 gm/dl. Hgb level alone was a significant predictor only at levels below 3 gm/dl (P less than .05). Extraction ratio interacted with Hgb only below 3 gm/dl (P less than .05). Multiple independent factors influence outcome in the severely anemic patient, the strongest being sepsis and active bleeding. Prevention of sepsis and early intervention to stop bleeding should improve survival in the patient who refuses transfusion.

Anemia↗
PubMed1991

Bradykinin agonist activity of a novel, potent oxytocin antagonist.

From a series of potent cyclic hexapeptide oxytocin (OT) antagonists, a compound that exhibited significant bradykinin (BK) agonist activity was identified. L-366,811 (cyclo[L-proline-D-tryptophan-L-isoleucine-D-pipecolic acid-L-piperazine-2-carboxylic acid-N-Me-D-phenylalanine]) stimulated phosphatidylinositol (PI) turnover in rat uterine slices in vitro (approximately EC50, 2 microM) with a maximal effect (15-fold increase over basal) greater than that obtained for either BK or OT. L-366,811 also elicited dose-related contractions of the isolated rat uterus, producing measurable effects at 100 nM. Several other equally potent OT antagonists from the cyclic hexapeptide structural class were either less potent or inactive as activators of uterine PI turnover or contractility. The stimulatory effects of L-366,811 on uterine PI turnover and contractions were blocked by BK antagonists but not by an arginine vasopressin (AVP)/OT antagonist. In radioligand binding studies, L-366,811 exhibited moderate affinity (IC50, 360 nM) for the [3H]BK binding site in rat uterus, consistent with its potency in the functional models. These results indicate that L-366,811 exhibits BK agonist activity in rat uterus in vitro.

Animals↗
PubMed1990

Macromolecular synthesis in the isolated rat myointima in vitro.

The myointima, which forms within the lumen of the carotid artery of the rat in response to the removal of the endothelium by a balloon catheter, could be extruded from the vessel as early as 6 days after denudation. The mean concentration of DNA in the isolated myointima increased as the myointima grew in vivo until 12 to 14 days after denudation, when the arterial lumen was filled with the myointima; thereafter the mean concentration of DNA declined. DNA and protein synthesis, incorporation of 3H-glucosamine and 3H-fucose into macromolecules, occurred in the myointima during incubation in vitro in the absence of fetal bovine serum, and with the exception of 3H-glucosamine, failed to be stimulated by it. These data indicate that the cells of the intact myointima do not require exogenous macromolecular growth factors for the synthesis of macromolecules in vitro.

Animals↗