Biomedical subjects

S L Simpson

Publications and source records attributed to S L Simpson.

11 recordsLinked to original sources

PubMed2001

A rapid screening method for acid-volatile sulfide in sediments.

A new, direct method for the determination of acid-volatile sulfide (AVS) in sediments is presented. The method utilizes the direct reaction of Clines reagent with small amounts of sediment followed by colorimetric determination of AVS and offers fast analysis times without the need for specialized glassware or equipment. A comparison between AVS measured by this method and that measured by a purge-and-trap AVS method shows a linear relationship (r = 0.986, p < 0.001), although the method underestimates the AVS concentration measured by the purge-and-trap method. Sample throughput by the direct AVS method is more than 10 times that of purge-and-trap methods. The applicability of the direct AVS method to the rapid screening of AVS concentrations in sediments and for evaluating sediment quality with respect to metal contamination is demonstrated.

Acids↗

PubMed1999

Effect of moderate alcohol consumption on hypertriglyceridemia: a study in the fasting state.

BACKGROUND: Patients with hypertriglyceridemia (HTG) are generally advised to avoid alcohol, even though moderate alcohol consumption is cardioprotective. Alcohol increases plasma triglyceride concentration transiently in normolipidemic subjects, but whether alcohol consumption per se increases triglyceride concentrations in patients with HTG is unclear. OBJECTIVE: To assess whether baseline fasting triglyceride concentration determines plasma triglyceride concentration after acute oral alcohol intake. METHODS: Twelve persons with fasting triglyceride concentrations of 2.3 to 8.5 mmol/L (200-750 mg/dL) and 12 persons as a non-HTG group were enrolled. Obesity, current smoking, and history of hypertension, diabetes, or excessive alcohol use were exclusionary. Fasted subjects consumed 38 mL of ethanol in water (equivalent, 2 alcoholic drinks); blood samples were collected at baseline and at intervals thereafter for 10 hours. No less than 1 week later, the subjects consumed water alone in a control test. RESULTS: Mean triglyceride values were 4.04+/-0.41 mmol/L (358+/-36.9 mg/dL) and 1.00+/-0.11 mmol/L (89+/-10.2 mg/dL) for the HTG and non-HTG groups, respectively. Despite similar changes with alcohol feeding in plasma ethanol, nonesterified fatty acid, and acetate concentrations, the groups differed in triglyceride response. At 6 hours (peak) compared with baseline, triglyceride concentration increased only 3% in the HTG group but 53% in the non-HTG group. The former change was not significantly different from the effect with water alone (-9.2% from baseline; P = .43), whereas the latter was (-8.0%; P = .003). CONCLUSIONS: Acute alcohol intake alone is not an important determinant of plasma triglyceride concentration in individuals with HTG. Other factors, such as the contemporaneous consumption of fat and alcohol, known to increase triglyceride concentrations synergistically in non-HTG individuals, may be more important.

Adult↗

PubMed1999

The potential to identify South Asians using a computerised algorithm to classify names.

Ethnic studies are limited by the lack of information on ethnic origin in data sources. This paper examines a computerised approach to identify South Asians by names. Computerised analysis of names is not an ideal solution, but it helps to solve the methodological difficulty of identifying South Asians, particularly in historical administrative datasets where self-assessed ethnicity is not possible and visual inspection is too time consuming and prone to errors. This approach, though useful, is limited to groups easily distinguishable by name and the collection of information on ethnicity should remain the aim in the long-term.

Adult↗

PubMed1998

The Drosophila Medea gene is required downstream of dpp and encodes a functional homolog of human Smad4.

The Transforming Growth Factor-beta superfamily member decapentaplegic (dpp) acts as an extracellular morphogen to pattern the embryonic ectoderm of the Drosophila embryo. To identify components of the dpp signaling pathway, we screened for mutations that act as dominant maternal enhancers of a weak allele of the dpp target gene zerknŁllt. In this screen, we recovered new alleles of the Mothers against dpp (Mad) and Medea genes. Phenotypic analysis of the new Medea mutations indicates that Medea, like Mad, is required for both embryonic and imaginal disc patterning. Genetic analysis suggests that Medea may have two independently mutable functions in patterning the embryonic ectoderm. Complete elimination of maternal and zygotic Medea activity in the early embryo results in a ventralized phenotype identical to that of null dpp mutants, indicating that Medea is required for all dpp-dependent signaling in embryonic dorsal-ventral patterning. Injection of mRNAs encoding DPP or a constitutively activated form of the DPP receptor, Thick veins, into embryos lacking all Medea activity failed to induce formation of any dorsal cell fates, demonstrating that Medea acts downstream of the thick veins receptor. We cloned Medea and found that it encodes a protein with striking sequence similarity to human SMAD4. Moreover, injection of human SMAD4 mRNA into embryos lacking all Medea activity conferred phenotypic rescue of the dorsal-ventral pattern, demonstrating conservation of function between the two gene products.

Amino Acid Sequence↗

PubMed1997

Survival estimates for patients with abnormal swallowing studies.

OBJECTIVE: To better understand the life expectancy of patients who have an abnormal videofluoroscopic swallowing study. DESIGN: Retrospective cohort study. The common starting point was the time of the severely abnormal swallowing study. Hospital charts were reviewed for clinical variables of potential prognostic significance by reviewers blinded to the outcome of interest, survival time. SETTING: A university-affiliated, community teaching hospital. PATIENTS: One hundred forty-nine hospitalized patients who were deemed nonoral feeders based on their swallowing study. Patients excluded were those with head, neck, or esophageal cancer, or those undergoing a thoracotomy procedure. MEASUREMENTS AND MAIN RESULTS: Clinical and demographic variables and time until death or censoring were measured. Overall 1-year mortality was 62%. Multivariable Cox proportional hazards analyses identified four variables that independently predicted death: advanced age, reduced serum albumin concentration, disorientation to person, and higher Charlson comorbidity score. Eighty patients (54%) subsequently underwent placement of a percutaneous endoscopic gastrostomy (PEG) tube after their swallowing study. CONCLUSIONS: Mortality is high in patients with severely abnormal swallowing studies. Common clinical variables can be used to identify groups of patients with particularly poor prognoses. This information may help guide discussions regarding possible PEG placement.

Aged↗

PubMed1997

Thigh pain and total hip arthroplasty: scintigraphy with 2.5-year followup.

From January 1988 to May 1990, 60 patients underwent 68 total hip arthroplasties at the Eisenhower Army Medical Center. The authors excluded 11 patients (11 hips) in whom infection developed, who were lost to followup, or who had incomplete records, leaving 49 patients (57 hips) as the study population. The 35 uncemented and 22 cemented femoral stems were evaluated with technetium bone scans at 1 week, 6 months, 1 year, and 2.5 years after surgery. Patients with uncemented femoral stems had markedly more thigh pain and more radiopharmaceutical uptake around the stem tip at 2.5 years followup than did patients with cemented femoral stems. In addition, patients with thigh pain had more uptake around the stem tip and a higher incidence of bone hypertrophy around the stem tip than did those without thigh pain, suggesting stress transfer as a cause of thigh pain.

Adult↗

PubMed1995

Identification of a low specificity, oxygen, heme, and growth phase regulated DNA binding activity in Saccharomyces cerevisiae.

Cytochrome c oxidase from Saccharomyces cerevisiae is subject to intricate control at the level of transcription of the various genes encoding its subunits. Expression of the subunit VI encoding gene, COX6, is glucose repressed, growth phase induced, and dependent on oxygen and heme availability. An upstream activation region for COX6, UAS6, was found to contain a glucose responsive region, a heme dependent region (HDS1), and a binding site for the transcription factor, BAF1. BAF1 was the only factor observed to form a protein complex with UAS6 in vitro. However, we found that binding of BAF1 was unaffected by oxygen or heme regulation. In the present communication, we have identified a DNA binding activity that was growth phase induced and dependent on oxygen and heme availability. This highly regulated activity was detected by its discrete binding to the heme responsive site, HDS1, in UAS6. Nonetheless, it appears to have weak DNA binding specificity.

Base Sequence↗

PubMed1995

Oxygen regulation of the cytochrome c oxidase subunit VI gene, COX6, in Saccharomyces cerevisiae.

Cytochrome c oxidase (CcO) in Saccharomyces cerevisiae is subject to intricate physiological control. Growth phase, carbon source, and oxygen level are three well recognized modulators of CcO expression. We focused on the subunit VI encoding gene, COX6, and detected unexpectedly complex oxygen regulation. We found that COX6 transcription possessed a critical threshold oxygen regulation between 0 and 2%. COX6 transcription was superinduced by elevated oxygen level up to 45%; however, superinduction was lost at 60% oxygen and above. The COX6 upstream activation region, UAS6, contains both glucose and heme responsive regions, and COX6 oxygen regulation was transduced through UAS6 by heme, as has been described for other oxygen regulated genes in yeast. We found that binding of the UAS6-domain 1 protein, BAF1, was unaltered by oxygen regulation. Nor were the alternative BAF1 complexes observed by growth in different glucose conditions formed by growth at different oxygen levels.

Base Sequence↗

PubMed1995

pH and the cAMP-dependent protein kinase mediate growth phase induction of the cytochrome c oxidase subunit VI gene, COX6, in Saccharomyces cerevisiae.

Respiratory adaptation in Saccharomyces cerevisiae is a complex genetic program that ensures ATP synthesis in a glucose-depleted environment. ATP is generated during respiration by the mitochondrial electron transport chain which is induced by respiratory adaptation. We have studied the terminal enzyme in mitochondrial electron transport, cytochrome c oxidase, from S. cerevisiae. Because subunits in this multisubunit enzyme are coordinately regulated, we have focused upon the well characterized subunit VI gene, COX6. In yeast, COX6 transcription is regulated by several factors thought to mediate respiratory adaptation including growth phase induction, oxygen dependence, and glucose repression. In the present study, we found that in addition to these known regulators, COX6 expression also depends upon pH and the cAMP-dependent protein kinase which may comprise additional factors signaling respiratory adaptation.

Cyclic AMP-Dependent Protein Kinases↗

PubMed1991

The plantaris tendon graft: an ultrasound study.

To assess the value of ultrasound in imaging the plantaris tendon, ultrasounds were done on 26 legs in 25 patients who had a variety of surgical procedures on the posterior leg. Eighteen ultrasounds were done and interpreted before operation and eight after operation by a radiologist. The sonographic results were compared with the status of the plantaris as determined at surgery. The plantaris was present in 21 of 23 patients for a prevalence of 91%. Eighteen plantaris tendons were well visualized on ultrasound for a sensitivity of 86%. Of the three false-negative results, two occurred with thinned plantaris tendons that were less than 2 mm thick and hence considered inadequate for grafting. Therefore, the sensitivity for detecting a tendon suitable for grafting was 95%. All patients with positive studies had a plantaris tendon present for a specificity of 100%. A learning curve for the radiologist was demonstrated. Ultrasound appears to be effective in the preoperative imaging of the plantaris tendon.

Achilles Tendon↗

PubMed1990

A comparative study of ultrasonography and arthrography in evaluation of the rotator cuff.

Fifty patients with signs and symptoms of chronic impingement syndrome and/or rotator cuff tear were evaluated with shoulder arthrograms and ultrasonography. Ninety asymptomatic shoulders of a comparable age had ultrasonography to serve as a control group. All controls had normal ultrasonograms with no hypoechoic or sonolucent areas. The 50 symptomatic shoulder patients had the following: 28 had a normal arthrogram with either normal ultrasonograms or buckling of the supraspinatus tendon; eight had normal arthrograms, but ultrasonography indicated a thin (less than 4 mm) irregular supraspinatus tendon; 11 had complete rotator cuff tears visualized on both arthrography and ultrasonography (nine of these 11 patients had surgery confirming complete tears in all); two had a false-positive sonogram, and one had a false-negative sonogram. Thus, the ultrasonography's overall positive predictive value to detect a full-thickness rotator cuff tear was 85%, its negative predictive value was 97%, its sensitivity was 92%, and its specificity was 95%. Real-time ultrasonography is a diagnostically sensitive and specific noninvasive method to evaluate patients with shoulder impingement syndrome, leading to the recommendation that it be used as a primary imaging technique to obviate or supplement arthrography in evaluating rotator cuff disease. However, static ultrasonographic pictures, without real-time ultrasonography as a supplement, were not helpful.

Adult↗