Biomedical subjects
Publications and source records attributed to T Burke.
Transdermal drug delivery provides an effective and advantageous alternative to the oral delivery of therapeutic agents. Currently, many other drugs are being evaluated for transdermal delivery including testosterone, fentanyl, nicotine and timolol. They offer the promise of simplified dosage regimens, enhanced compliance, reduced side effects and improved therapy of disease.
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Radionuclide assessment of pulmonary capillary protein leak using [99mTc] human serum albumin (99mTc-HSA) was first reported from our laboratory. In this study we investigated the impact of 1) sampling time post tracer injection, and 2) lung region assignment, on diagnostic accuracy between 2 groups (control n = 20 and ARDS n = 20). Each patient received 370 MBq 99mTc-HSA i.v. and was imaged for 45 min. The slope index (SI) [change in lung: heart activity ratio/min] was calculated from 11 computer assigned lung regions for intervals of 5-15 (early [E]) and 15-45 (late [L]) min. The diagnostic accuracy of E vs L SI calculations for the 11 regions was evaluated by stepwise logistic regression. E SI data and L SI data from the lower 1/3 of the lung did not achieve significance for inclusion in the discriminant model (P less than 0.05). In the nine remaining regions L SI was significant. Optimal discrimination was achieved from L SI data obtained from a region confined to the lateral half of the mid 3rd of the lung field (sensitivity 81%, specificity 85%, accuracy 83%). The results confirm that: 1) a late (15-45 min) sampling period and 2) proper region assignment are necessary to maximize accuracy of this technique.
Membranes were isolated from B cells stimulated with phorbol 12-myristate 13-acetate (PMA) for a time sufficient to allow maximal redistribution and activation of protein kinase C (PKC). Exposure of such membranes to a short incubation with [gamma-32P]ATP resulted in the detection of at least nine unique or hyperphosphorylated membrane proteins by SDS-PAGE and autoradiography. The appearance of these phosphoproteins was blocked by pretreatment of the membranes with H-7 or sangivamycin, two selective inhibitors of PKC. In addition, membranes purified from B cells treated with an inactive phorbol ester or stimulated with dibutyryl cAMP failed to exhibit a pattern of new phosphoproteins. These results are consistent with the involvement of PKC in the phosphorylation of the proteins. These phosphoproteins are also candidates for proteins whose functions are modified as a consequence of early signal delivery to resting B cells following membrane immunoglobulin occupancy. This system was utilized to identify the heavy chain of MHC class I molecules as one of the membrane proteins phosphorylated by PKC. The MHC class II molecules were not phosphorylated in membranes isolated from PMA-treated normal B cells or from PMA-treated B cells which had previously been exposed to IL-4. These results indicate that class I, but not class II, MHC molecules are phosphorylated by PKC. It is possible that such a modification of cell surface class I molecules may be involved during the process of signal transduction leading to B cell activation.
Four genes expressed during the period of vitelline membrane formation are clustered within 8 kb of DNA in region 26A of the second chromosome. Temporal and quantitative difference in the profiles of accumulated RNA suggest that the genes are independently regulated although they are selectively expressed during the stages of vitelline membrane biosynthesis. In situ hybridization and S1 analyses of RNAs from fractionated eggchambers established that these genes are active only in the follicle cells. S1 mapping with in vitro synthesized RNA probes shows that three of the genes are tandemly oriented. All four appear to be intronless. In vitro translation products from hybrid-selected RNAs indicate that two of these genes code for major vitelline membrane proteins. Sequence analysis of these two genes support this conclusion. The cell- and stage-specific expression of the other two genes, encoding less abundant RNAs, suggests that they also play a role in early eggshell production.
Aminooligopeptidase is an intrinsic glycoprotein of the brush border membrane important for hydrolysis of the oligopeptide products of intraluminal protein digestion. To study its synthesis and intracellular processing, we performed pulse-chase experiments using [35S]methionine to label proteins of cultured human intestinal explants obtained by endoscopic biopsy. Aminooligopeptidase was isolated by immune precipitation with a monoclonal antibody and its molecular size was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography. A precursor of relative molecular weight (Mr) 127,000 appeared within 10 min of chase and appeared to begin conversion to an Mr 150,000 form (the size of brush border membrane aminooligopeptidase) within 60 min. To determine if the change in molecular size was the consequence of alterations in glycosylation, we studied the susceptibility of the two forms to endo-beta-N-acetylglucosaminidase H, which cleaves immature high-mannose N-linked carbohydrate chains, and to peptide: N4-(N-acetyl-beta-glucosaminyl)asparagine amidase, which cleaves both the high-mannose and complex N-linked carbohydrate chains. Only the early Mr 127,000 aminooligopeptidase was sensitive to endo-beta-N-acetylglucosaminidase H, suggesting that the larger form results from trimming of high-mannose cores and adding terminal sugars in the Golgi complex. Both forms were sensitive to peptide: N4-(N-acetyl-beta-glucosaminyl)asparagine amidase, generating an Mr 114,000 species. The kinetics of the synthesis and processing of aminooligopeptidase and sucrase-isomaltase were compared by immunoprecipitation of both proteins from the same tissue after separating the microvillous membrane from the remainder of the cellular membranes. Labeled aminooligopeptidase was present intracellularly in its mature form within 60 min and was detected exclusively in the brush border membrane by 90 min. Most of the labeled sucrase-isomaltase pool had not yet undergone complex glycosylation during the same period. These data demonstrate that although human intestinal aminooligopeptidase undergoes N-linked glycosylation like sucrase-isomaltase, the synthesis of aminooligopeptidase differs from that of sucrase-isomaltase in respect to the absence of a high-molecular-weight precursor and more rapid pre-Golgi processing.
Dermatofibrosarcoma protuberans of the vulva is an extremely rare neoplasm. This low-grade sarcoma of the dermis clinically appears to be encapsulated but microscopically has tumor projections well away from the central nodules. Wide local excision is the recommended treatment for dermatofibrosarcoma protuberans; however, a more radical surgical approach may be needed to obtain clear surgical margins. The following case study present the fifth reported patient with this unusual neoplasm on the vulva.
Fifty patients underwent superficial temporal lobectomy for intractable temporal lobe epilepsy. Total cure rate was 52%, and significant improvement was achieved in 88%. Cytoarchitectural changes in gray and white tissue were analyzed under light microscopy. Neuronal dysgenesis was correlated with the duration of seizure disorder, age of onset, and other etiologic factors, and with clinical outcome. Temporal lobes from 33 neurologically normal autopsy brains which were age- and sex-matched with patients were examined as controls. Severe neuronal ectopia (greater than 8 neurons/2 mm2 white matter) was present in 42% of patients with epilepsy and in none of controls. There was neuronal clustering in 28% of those with epilepsy, and Chaslin's (subpial) gliosis in 38%. Controls did not have these changes. The presence of severe neuronal ectopia and clustering was predictive of a favorable clinical outcome following surgery (p less than 0.05). No correlation was found between microdysgenesis and other factors. These findings suggest that the presence of neuronal dysgenesis may be of significance in the clinical outcome following surgery, and that the abnormal tissue may be important as a morphologic substrate for seizures in some patients.
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Four patients with bilateral simultaneous rupture of the quadriceps tendons were each older than 70 years of age. In the first patient the diagnosis was missed and one side was managed conservatively, while the other side was surgically treated. A combination of inadequate postoperative immobilization and the use of chromic catgut sutures probably caused failure of the repair, requiring revision surgery. The other three patients were treated by bilateral operative repair and had satisfactory results. Nonabsorbable suture material use and a minimum period of six weeks of postoperative immobilization are recommended.
To isolate genes involved in vitelline membrane production, an ovarian cDNA library was screened with eggchamber RNAs labeled in vivo. Two cDNA clones encoding RNAs that are selectively expressed in follicle cells during the period of vitelline membrane formation were isolated. Following isolation of homologous genomic clones from a Drosophila library, one gene was localized by in situ hybridization to chromosomal region 26A, and the other to 3C. Developmental Northern blots demonstrated that both genes produce 700-800 nucleotide transcripts that accumulate during the stages of vitelline membrane synthesis. In vitro translation products from hybrid selected RNAs and DNA sequence analysis both indicate that the 26A region gene encodes a major protein component of the vitelline membrane. The structural properties of the 3C region follicle cell gene seem more compatible with an intracellular function.
Wide excision is the recommended primary therapy for retroperitoneal fibromatosis. Radiation therapy and a variety of medications have been used to treat patients with recurrent tumors, but the response to these agents has not been uniform. The patient presented was successfully treated with medroxyprogesterone acetate for recurrent retroperitoneal fibromatosis that was refractory to multiple operative resections and radiation therapy.
We are using the isoenzymes of creatine kinase (CK) to investigate the effect of specific proteolytic modification on the abilities of enzyme subunits to establish precise subunit-subunit recognition in vitro. Previous work by others has shown that treatment of the MM isoenzyme of rabbit CK with Proteinase K results in a specific proteolytic modification and inactivation of the enzyme. In the present work, we show that both the MM and BB isoenzymes of chicken CK are also specifically modified by Proteinase K, resulting in over 98% loss of catalytic activity and approx. 10% decreases in subunit molecular masses of the enzymes. Similar reactions appear to occur when the isoenzymes are treated with Pronase E. Limited amino acid sequence analysis of intact and Proteinase K-modified MM-CK suggests that the proteolytic modification results from a single peptide-bond cleavage occurring between alanine residues 328 and 329, about 50 amino acid residues from the C-terminal end; the active-site cysteine residue was recovered in the large protein fragment of modified M-CK subunits. Proteolytically modified M-CK and B-CK subunits were able to refold and reassociate into dimeric structures after treatment with high concentrations of LiCl and at low pH. Thus the proteolytically modified CK subunits retain their ability to refold and to establish precise subunit-subunit recognition in vitro.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.