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Biomedical subjects

C E Smith

Publications and source records attributed to C E Smith.

At least 91 records · Page 5Linked to original sources
PubMed1996

Anemia and perioperative myocardial ischemia in a Jehovah's Witness patient.

We present a case in which an anemic patient with religious objections to blood transfusion experienced three episodes of severe myocardial ischemia during the perioperative period. The first episode of ischemia was successfully treated by discontinuing isoflurane and resolving the hypotension. The second and third episodes were successfully treated by heart rate control with esmolol and neostigmine.

Adrenergic beta-Antagonists↗
PubMed1996

Comparison of esophageal, tympanic, and forehead skin temperatures in adult patients.

STUDY OBJECTIVE: To compare esophageal, tympanic membrane, and forehead skin temperatures in patients undergoing elective surgeries. DESIGN: Prospective clinical study. SETTING: Operating room and postanesthesia care unit of a tertiary care teaching hospital. PATIENTS: 40 adult ASA status I, II and III patients requiring anesthesia and surgery. INTERVENTION: Application of crystalline thermometry strips to the forehead of patients. MEASUREMENTS AND MAIN RESULTS: Concurrent forehead skin, tympanic membrane, and lower esophageal temperatures were measured and compared. The overall bias between esophageal and skin temperatures was 0.3 degrees C, between tympanic membrane and skin was 0.5 degrees C, and between esophageal and tympanic membrane was -0.1 degrees C The limits of agreement (precision) between esophageal and skin temperatures were: -1.64 degrees C to +2.32 degrees C, between esophageal and tympanic membrane were: -1.02 degrees C to +0.74, and between tympanic membrane and skin were: -1.48 degrees C to +2.52 degrees C. There was no significant relation between the change in skin temperature and change in esophageal temperature, whereas there was a weak linear relation between change in skin temperature and change in tympanic membrane temperature (y = -0.03 + 0.09, r = 0.12). CONCLUSION: There was a lack of precision between the clinically accepted measurements (lower esophageal and tympanic membranes and the skin temperature measurement. The data suggest that forehead skin temperature is not interchangeable with standard core temperature measurements, and that sole reliance on the forehead skin measurement in the perioperative setting could adversely affect patient care.

Adult↗
PubMed1996

Simulated clinical evaluation of conventional and newer fluid-warming devices.

The purpose of the study was to evaluate the ability of five commercially available devices utilizing a variety of heat exchange technologies to deliver normothermic (37 degrees C) fluids. Conditions of slow (6.5 mL/ min), moderate (13-25 mL/min), and rapid (gravity and pressure driven flows, roller clamp wide open) infusion were simulated. Fluid temperatures were measured using rapid response thermistors after the fluid exited the heat exchanger (T outlet) and before delivery to the patient intravenously (IV) (T distal). Devices tested were the FW537, H1000, Hotline, BairHugger, and Flotem IIe. Fluids tested were crystalloid at room temperature and red cells diluted with saline (11-19 degrees C). At slow and moderate flows, T distal of crystalloid was between 35.3 and 37.9 degrees C for Hotline at 42 degrees C, 33.8 and 37.7 degrees C for H1000 at 42 degrees C, 29.4 and 34.2 degrees C for BairHugger, 26.1 and 31.5 for Flotem IIe, and 23.8 and 32.1 for FW537 at 42 degrees C. With gravity and pressure driven flows, T distal of crystalloid were 39.0 and 38.9 for H1000 at 42 degrees C, 38.7 and 38.4 degrees C for FW537 at 42 degrees C, 34.7 and 28.9 degrees C for Hotline at 42 degrees C, 29.2 and 24.2 degrees C for BairHugger, and 29.7 and 24.2 degrees C for Flotem. In conclusion, only the H1000 at 42 degrees C was effective at delivering normothermic fluids at all clinically relevant flow rates. The Hotline at 42 degrees C was effective at slow and moderate flow, whereas the FW537 was effective only at rapid flow.

Crystalloid Solutions↗
PubMed1996

Opossum colonic mucosa contains uroguanylin and guanylin peptides.

Uroguanylin and guanylin are structurally related peptides that activate an intestinal form of membrane guanylate cyclase (GC-C). Guanylin was isolated from the intestine, but uroguanylin was isolated from urine, thus a tissue source for uroguanylin was sought. In these experiments, uroguanylin and guanylin were separated and purified independently from colonic mucosa and urine of opossums. Colonic, urinary, and synthetic forms of uroguanylin had an isoelectric point of approximately 3.0, eluted from C18 reverse-phase high-performance liquid chromatography (RP-HPLC) columns at 8-9% acetonitrile, elicited greater guanosine 3', 5'-cyclic monophosphate (cGMP) responses in T84 cells at pH 5.5 than pH 8, and were not cleaved and inactivated by pretreatment with chymotrypsin. In contrast, colonic, urinary, and synthetic guanylin had an isoelectric point of approximately 6.0, eluted at 15-16% acetonitrile on C18 RP-HPLC columns, stimulated greater cGMP responses in T84 cells at pH 8 than pH 5.5, and were inactivated by chymotrypsin, which hydrolyzed the Phe-Ala or Try-Ala bonds within guanylin. Uroguanylin joins guanylin as an intestinal peptide that may participate in an intrinsic pathway for cGMP-mediated regulation of intestinal salt and water transport. Moreover, uroguanylin and guanylin in urine may be derived from the intestinal mucosa, thus implicating these peptides in an endocrine mechanism linking the intestine with the kidney.

Amino Acid Sequence↗
PubMed1996

Transient accumulation of proteins at interrod and rod enamel growth sites.

Conceptually, there should be a brief interval in time when newly secreted proteins "pile up" at secretory sites just outside the membrane of ameloblasts. Indeed, previous cytochemical studies have suggested that glycosylated and/or sulfated glycoproteins accumulate at enamel growth sites. Colloidal gold lectin cytochemistry and immunocytochemistry with antibodies to enamel proteins and phosphoserine, combined with cycloheximide and brefeldin A to inhibit protein synthesis and secretion, were applied to characterize the distribution of newly formed proteins at enamel interrod and rod growth sites. Although enamel growth sites show a "rarefied" appearance, the results indicate that one or more subclasses of enamel proteins accumulate near the cell surface at sites where elongation of enamel crystallites contributes to thickening of the enamel layer. These proteins are glycosylated and/or phosphorylated and, at least in the case of the glycosylated ones, are rapidly processed after they are released extracellularly. In contrast, immunolabeling for amelogenins is generally weaker near the cell surface and more intense at a short distance away from the site where crystallites elongate. The data suggest that the enamel proteins accumulating at growth sites likely belong to the non-amelogenin category and play a transient role in promoting the lengthening of crystallites. It is concluded that areas near the ameloblast membrane where certain enamel proteins accumulate in fact constitute the equivalent of a mineralization front.

Ameloblasts↗
PubMed1996

Developmental changes in the pH of enamel fluid and its effects on matrix-resident proteinases.

The objectives of this study were to measure pH in developing enamel at progressively older (more mature) stages of amelogenesis in vivo, and then to formulate synthetic enamel fluid mixtures that approximated these pH values for in vitro studies. The ultimate goal was to characterize the molecular weights of proteinases visualized by enzymograms incubated in synthetic enamel fluid using gelatin and casein as substrates. For most experiments, the proteinases were extracted en masse from small freeze-dried enamel strips directly into a non-reducing sample preparation buffer. In some experiments, we pre-treated the enamel strips with acetic acid to determine if this common method for demineralization and protein extraction caused any changes in the activity levels of the enamel proteinases. In other experiments, we first soaked enamel strips in synthetic enamel fluid to determine solubility of the proteinases within an aqueous phase. The results indicated that the pH of developing enamel remained fairly constant near pH 7.23 across the secretory stage, but it was generally more acidic (6.93) and fluctuated in focal areas between mildly acidic (6.2-6.8) and near-neutral (7.2) conditions across the maturation stage. The pH then slowly rose to near 7.35 when the enamel was almost mature (hard). The acidic conditions were generally inhibitory to most enamel proteinases, but there were some caseinase activities in mid-maturation-stage enamel near 23-30 kDa which appeared to be activated by weakly acidic conditions (pH 6.28). Pre-treatment of enamel samples with 0.5 M acetic acid markedly altered the overall profile of enamel proteinases, causing activation of some latent proteinase activities and permanent inhibition of other activities. Most proteinases in whole homogenates were insoluble in synthetic enamel fluid. This suggests that they may be tightly bound, directly or indirectly, to matrix proteins or mineral components in situ.

Acetic Acid↗
PubMed1996

Ultrastructural localization of the C-propeptide released from type II procollagen in fetal bovine growth plate cartilage.

We used immunochemical and immunoelectron gold techniques to determine whether the C-propeptide previously identified in the matrix of endochondral cartilage (CPII) was still a part of the Type 11 procollagen molecule or had been released from it. Guanidinium hydrochloride extraction, followed by SDS-PAGE and Western blotting techniques and immunoelectron localization, revealed that predominantly only the released form (hereafter referred to as released CPII) was detected. The ultrastructural distribution of this CPII was examined with affinity-purified antibodies and with immunogold or immunoperoxidase localization techniques in the presence or absence of embedding resins. These methods yielded similar results. Although no significant amount of this CPII was retained in the matrix after guanidinium hydrochloride extraction, it was present in two recognizable sites under normal conditions, i.e., locally concentrated in a random association with collagen fibrils in the nonmineralized matrix and mainly concentrated in interfibrillar mineralizing sites in the mineralized matrix. These results suggest that the C-propeptide that has been released from Type II procollagen associates with collagen fibrils and then preferentially associates with mineralizing sites when these form in the endochondral cartilage. The significance of this preference for mineral is not known but may have something to do with its high affinity for hydroxyapatite.

Animals↗
PubMed1996

Prouroguanylin and proguanylin: purification from colon, structure, and modulation of bioactivity by proteases.

Uroguanylin and guanylin are peptides isolated from urine and intestinal mucosa, which regulate cyclic GMP production in enterocytes by activating an apical membrane, receptor-guanylate cyclase. This study extended our previous findings, which showed that colonic mucosa of opossums contained uroguanylin and guanylin peptides, by purifying prouroguanylin and proguanylin from this tissue. Prouroguanylin and proguanylin coeluted from Sephadex G-75 gelfiltration columns with a similar molecular size between 6 and 12 kDa. Mass spectrometry indicated that proguanylin (approximately 8.7 kDa) had a 10% lower molecular mass than prouroguanylin (approximately 9.7 kDa). Isoelectric focusing separated prouroguanylin (pI approximately 4.5) from proguanylin (pI approximately 7.5). N-terminal sequence analysis of reverse phrase-HPLC purified prohormones revealed 13 amino acids in opossum proguanylin that shared 77-85% identity with human and rat proguanylin, but only 23% identity with opossum prouroguanylin. The N-terminal 19 residues obtained for opossum prouroguanylin shared 32-42% identity with rat and human proguanylin. Prouroguanylin and proguanylin were both inactive and required pretreatment with proteases to elicit cyclic GMP responses in T84 cells. V8 protease treatment of proguanylin liberated a bioactive, 16-amino acid form of guanylin. Chymotrypsin treatment activated prouroguanylin, but inactivated the bioactive peptide domain within proguanylin. In summary, colonic mucosa contains the bioactive peptide and inactive prohormone forms of uroguanylin and guanylin. Thus, after proteolytic processing of prouroguanylin and proguanylin, bioactive uroguanylin and guanylin could both function to regulate guanylate cyclase activity by autocrine and/or paracrine actions on enterocytes. Also, these peptide hormones are implicated in an intestinal-renal axis for the endocrine regulation of salt and water homeostasis.

Amino Acid Sequence↗
PubMed1996

Acute fluoride ingestion: recognition and management.

Occasionally, the Oral Health Division of the Indiana State Department of Health receives inquiries regarding diagnosis and treatment of acute fluoride ingestion. Because a wide variety of fluoride preparations are available in the dental setting and over the counter, excessive ingestion of fluoride can occur if these products are not used properly. The following article is meant to be a quick and easy guide in the recognition and management of instances of acute fluoride ingestion.

Acute Disease↗
PubMed1995

Naturally processed peptides from rheumatoid arthritis associated and non-associated HLA-DR alleles.

Naturally processed peptides from immunoaffinity-purified HLA-DRB1*0401, -DRB1*0404 (rheumatoid arthritis (RA)-associated), and -DRB1*0402 (non-RA-associated) molecules were analyzed by capillary liquid chromatography and mass spectrometry. The molecular weights observed for more than 60 eluted peptides from each HLA-DR protein ranged from 788 to 3535 atomic mass units, corresponding to peptides 7 to 32 amino acids in length. Sequencing of more than 60 of the abundant peptides revealed nested sets of peptides that were derived from only 12 different proteins. The majority of these proteins were membrane-associated (HLA class I, class II, and Ig molecules). Synthetic peptides, corresponding to endogenous peptide sequences, bound with high affinity (5 to 80 nM) to the HLA-DR molecules from which they were eluted. In addition, most were promiscuous binding peptides in that they also bound to other HLA-DR molecules. Truncations of eluted peptide sequences and alanine scanning mutational analysis of a Mycobacterium leprae peptide were used to identify the peptide residues involved in binding to DRB1*0404 and DRB1*0402 molecules. Furthermore, an invariant chain peptide was eluted from the DRB1*0402 molecules but not from the RA-associated molecules. The lack of invariant chain peptides from DRB1*0401 and DRB1*0404 molecules may contribute to the loading of autoantigen peptides into these molecules and to their association with disease.

Alleles↗
PubMed1995

Proteolytic cleavage of insulin-like growth factor binding protein 4 (IGFBP-4). Localization of cleavage site to non-homologous region of native IGFBP-4.

Insulin-like growth factor binding protein 4 (IGFBP-4) is a 24-kDa protein that binds insulin-like growth factor 1 (IGF-1) and IGF-2 with high affinity and inhibits IGF action in vitro. We recently described a protease produced by the B104 neuronal cell line that cleaves IGFBP-4, yielding an approximate 16-kDa immunoreactive protein that binds IGFs with reduced affinity. We analyzed fragments produced by exposing pure IGFBP-4 to the protease to determine potential cleavage sites. Electrospray mass spectrometry and amino acid sequencing indicated the 16-kDa fragment spanned the NH2 terminus of native IGFBP-4 through Lys-120. There was evidence for an additional proteolytic fragment beginning at amino acid 132 and continuing to the COOH terminus. Proteolysis could be blocked by a synthetic peptide that spanned amino acids 117-126 but not by peptides that contained flanking sequences 111-120 or 125-135. Mutagenesis was used to alter the basic residue at position 120. The expressed mutant IGFBP-4 (K120A) was relatively resistant to cleavage, strongly suggesting that residues 120-121 represent the cleavage site. This region of IGFBP-4 is not homologous with other IGFBPs, explaining the apparent specificity of the protease for IGFBP-4. The 16-kDa IGFBP-4 fragment no longer inhibited IGF-1-stimulated thymidine uptake in vitro, suggesting that proteolytic processing of IGFBP-4 may have important functional consequences in vivo.

Amino Acid Sequence↗
PubMed1995

The upregulation of Na+,K(+)-ATPase pump numbers in lymphocytes from the first-degree unaffected relatives of patients with manic depressive psychosis in response to in vitro lithium and sodium ethacrynate.

Patients with manic depressive disorder (DSM-III-R bipolar disorder) have an abnormality of the Na+,K(+)-ATPase pumps in their lymphocytes: the pump numbers do not upregulate to stimulation with lithium and ethacrynate. We have now investigated the in vitro adaptive responses of lymphocyte Na+,K(+)-ATPase pumps in the first-degree unaffected relatives of patients with a clear history of manic depressive disorder. The lymphocytes of the healthy relatives upregulated their Na+,K(+)-ATPase pumps normally, suggesting that the abnormal response that we have previously observed in patients with the disorder reflects a complex relation between the biochemical phenotype and the development of clinical symptoms.

Bipolar Disorder↗
PubMed1995

Enamel matrix protein turnover during amelogenesis: basic biochemical properties of short-lived sulfated enamel proteins.

The formation and turnover of sulfated enamel proteins was investigated by SDS-PAGE, fluorography, and TCA-precipitations using freeze-dried incisors of rats injected intravenously with 35S-sulfate (35SO4) and processed at various intervals from 1.6 minutes to 4 hours thereafter. Some rats were injected first with 35SO4 followed 5 minutes later by 0.3 mg of cycloheximide. This was done to terminate protein translation and allow events related to extracellular processing and degradation of the sulfated enamel proteins to be visualized more distinctly. Other rats were injected with cycloheximide followed at 0 minutes (simultaneous injection) to 30 minutes later by 35SO4. This was done to characterize the time required for proteins to travel from endoplasmic reticulum to Golgi apparatus, where they became sulfated. The results indicated that enamel organ cells (ameloblasts) rapidly incorporated 35SO4 into a major approximately 65 kDa protein that was secreted into the enamel within 6-7.5 minutes. This parent protein appeared to be processed extracellularly within 15 minutes into major approximately 49 kDa and approximately 25 kDa fragments which themselves had apparent half-lives of about 1 and 2 hours, respectively. There were also many minor sulfated fragments varying in molecular weight (Mr) from approximately 13-42 kDa, which appeared to originate from extracellular processing and/or degradation of the parent approximately 65 kDa sulfated enamel protein or its major approximately 49 kDa and approximately 25 kDa fragments. Experiments with glycosidases further suggested that the majority of sulfate groups were attached to sugars N-linked by asparagine to the core of the approximately 65 kDa sulfated enamel protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Amelogenesis↗
PubMed1995

Immunoblotting studies on artifactual contamination of enamel homogenates by albumin and other proteins.

The reason for the presence of albumin and other serum, cytoskeletal, cytosolic, and extracellular matrix proteins in enamel fractions was investigated by immunoblotting using homogenates prepared from freeze-dried and freshly dissected rat incisors, and antibodies capable of resolving at least 1 ng of the primary antigen. The data indicated that most of the 16 antibodies examined in this study reacted with antigens present only within "cell" homogenates (enamel organ cells + adhering labial connective tissue and blood vessels). One exception was rat serum albumin which was detected routinely in enamel homogenates prepared from freshly dissected, wiped incisors but rarely within enamel homogenates prepared from freeze-dried incisors. Another exception was calbindin-D 28 kDa which was consistently found within secretory stage enamel homogenates irrespective of preparative technique. A third exception was enamel proteins (amelogenins) which were enriched in secretory and early maturation stage enamel homogenates compared with cell homogenates and distributed as multiple molecular weight, antigenic bands in enamel homogenates (14-30 kDa), but mostly as a single antigenic band in cell homogenates (near 27 kDa). Overall, the results of this study suggest that developing rat incisor enamel naturally contains few exogenous proteins such as albumin. High concentrations of albumin (or other serum proteins) in crude homogenates, or purified fractions, derive mostly from blood and/or tissue fluids soaking into the enamel during sample preparation. This type of artifact can be avoided by using freeze-dried teeth for biochemical analyses.

Amelogenin↗
PubMed1995

Determination of the disulfide bond pairings in human tissue factor pathway inhibitor purified from Escherichia coli.

The disulfide bond assignments of human alanyl tissue factor pathway inhibitor purified from Escherichia coli have been determined. This inhibitor of the extrinsic blood coagulation pathway possesses three Kunitz-type inhibitor domains, each containing three disulfide bonds. The disulfide bond pairings in domains 1 and 3 were determined by amino acid sequencing and mass spectrometry of peptides derived from a thermolysin digest. However, thermolysin digestion did not cleave any peptide bonds within domain 2. The disulfide bond pairings in domain 2 were determined by isolating it from the thermolysin treatment and subsequently cleaving it with pepsin and trypsin into peptides which yielded the three disulfide bond pairings in this domain. These results demonstrate that the disulfide pairings in each of the three domains of human tissue factor pathway inhibitor purified from Escherichia coli are homologous to each other and also to those in bovine pancreatic trypsin inhibitor.

Amino Acid Sequence↗
PubMed1995

Evaluation of different methods of securing intravenous catheters: measurement of forces during simulated accidental pullout.

The purpose of the study was to compare the relative effectiveness of several combinations of tapes and taping methods with respect to the force required to pull out intravenous catheters. A simulated forearm model consisting of a section of firm PVC pipe was used for the first and second series of experiments. In the third experiment, one method of taping catheters was compared in the PVC model and in volunteers. Pullout forces were measured with a force transducer and recorded on paper. In the first experiment, catheters secured with Curity tape resisted pullout to a greater extent than those with Transpore tape and provided approximately twice the force advantage (P < 0.05). In the second experiment using Curity tape, minimum forces to dislodge the catheters were (means +/- SD) 53 +/- 13, 82 +/- 13, 113 +/- 29, 124 +/- 24, 176 +/- 29 and 141 +/- 46 N, for methods 1-6, respectively. In the third series, the minimum pullout forces were higher for Curity than with Transpore tape for both the human and simulated PVC forearm surfaces (63 +/- 11 and 55 +/- 12 N vs 52 +/- 7 and 44 +/- 12 N, P < 0.01), and the pullout forces were higher for the simulated vs. the human skin surface for both tape types (P < 0.01). Compared with Curity tape, Transpore tape was more likely to fail by tape fracture in both the simulated and human skin surfaces (P < 0.05). The data suggest that there are important differences in pullout forces and mechanisms of dislodgement depending on taping method and tape type.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗